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  • 1985-1989  (96)
  • 1960-1964  (21)
  • 1935-1939
  • 1920-1924
  • Catalysis
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  • Phosphorus
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  • 1
    Digitale Medien
    Digitale Medien
    Grundlagen der klinischen Ernährungstherapie und die Anwendung von Aminosäurenlösungen (1989)
    Springer
    European journal of nutrition 28 (1989), S. 211-224 
    Details
    ISSN: 1436-6215
    Schlagwort(e): Klinische Ernährungstherapie ; Aminosäurenlösungen,Aminogramme ; Key words ; Clinical nutrition ; amino acids, analytical interpretation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Medizin
    Beschreibung / Inhaltsverzeichnis: Summary The high value of clinical nutrition as an important component in polypragmatic therapy of severely ill patients with increasing age and restricted compensatory capacity is today unquestioned. The areas of interest and applications have reached a high degree of complexity by many differentiations. The metabolic interrelations under pathological conditions influence especially the application of amino acids. By the enormously increased standards of analytical procedures and instruments huge amounts of data have been gathered but methods and tools for interpreting the complex analytical results have not been developed to the same degree. Considering physiological, pathological biochemical, and biophysical alterations, this review discusses application of amino acids, evaluation and interpretation procedures, as well as indications, contraindications, and effective monitoring. The important regulatory function of the liver in connection with the urea production rate, and the physiological pattern and concentrations of amino acids in plasma are both discussed in detail. Also discussed is the therapeutic advantage of determining total concentration and relative composition of the amino acid pool in plasma, especially in severely ill patients.
    Notizen: Zusammenfassung Der hohe Stellenwert der klinischen Ernährungstherapie ist in der heutigen polypragmatischen Therapie schwerstkranker und zum Teil sehr alter Patienten mit eingeschränkter Kompensationsfähigkeit unbestritten. Das Einsatzfeld der klinischen Ernährungstherapie hat dadurch eine starke Differenzierung und einen hohen Komplizitätsgrad erreicht. Diese Wechselbeziehung des pathologischen Ablaufs im Stoffwechsel nach äußeren und inneren Belastungen und den einzelnen Substraten betrifft im hohen Maße die Anwendung von Aminosäuren. Durch die enorme Zunahme der analytischen Leistungsfähigkeit ist das Erkenntnismaterial im Bereich der Aminosäurenversorgung zwar stark angewachsen, aber die Interpretation des komplexen Zusammenhangs der Aminosäuren keineswegs in gleicher Weise verbessert worden. In der vorliegenden Arbeit wird auf dem grobskizzierten Hintergrund physiologischer und pathologischer Stoffwechselzusammenhänge der Einsatz von Aminosäuren dergestalt abgehandelt, daß über eine plausible Interpretation der komplexen analytischen Daten die Indikation, Kontraindikation und überwachung der Aminosäurenapplikation verständlich wird. Vor allem die Bedeutung der Regulation durch die Leber, der Zusammenhang mit der Harnstoffproduktionsrate sowie die differente Bedeutung der mikromolaren und relativen Aminosäurenmuster im Plasma werden so abgehandelt, daß sie für die Interpretation auch schwerkranker Zustände herangezogen werden können.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02023691
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  • 2
    Digitale Medien
    Digitale Medien
    Phosphorus fertilizer response in narrow-leafed lupin (Lupinus angustifolius L.) and chickpea (Cicer arietinum) compared to wheat (Triticum aestivum) in early growth (1989)
    Springer
    Nutrient cycling in agroecosystems 19 (1989), S. 1-6 
    Details
    ISSN: 1573-0867
    Schlagwort(e): Phosphorus ; lupin ; chickpea ; wheat ; nodulation ; dry matter production
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A glasshouse experiment was conducted to examine the comparative growth and P uptake response following P fertilizer application in lupins (Lupinus angustifolius L. cv. Chittick) and chickpeas (Cicer arietinum cv. Tyson) compared to wheat (Triticum aestivum cv. Sunstar). Measurements of dry matter, phosphorus uptake and nodule numbers were made at 50 and 100 days after sowing. At the 50 day harvest, the two legume crops produced less dry matter and accumulated less plant P than wheat but no such species interactions were present at the 100 day harvest. Chickpeas showed strong positive responses in nodule numbers with increasing rates of P fertilizer while such effects were less and more variable with lupins.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01080679
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  • 3
    Digitale Medien
    Digitale Medien
    Phosphorus transport to the bottom of Lake Constance (1989)
    Springer
    Aquatic sciences 51 (1989), S. 181-191 
    Details
    ISSN: 1420-9055
    Schlagwort(e): Phosphorus ; sedimentation ; Lake Constance ; particles ; calcite POM
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Despite decreasing nutrient loading of Lake Constance over the past few years, annual sedimentation rates of dry matter remained nearly constant at a level of about 1000 gm−2y−1. The phosphorus content in settling material varied between 0.13 and 0.22% of dry weight. Phosphorus was transported to the lake bottom mainly by POM and by coprecipitation with authigenically formed calcite (estimated from results of laboratory studies). Adsorption to sinking particles of allochthonous origin was of minor importance. The effect of a self-cleaning mechanism is discussed with regard to continuously declining contents of dissolved phosphorus in Lake Constance since 1981, due to external sanitation measures in the drainage area.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00877741
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  • 4
    Digitale Medien
    Digitale Medien
    Statistical models for the estimation of net phosphorus sedimentation in lakes (1989)
    Springer
    Aquatic sciences 51 (1989), S. 192-210 
    Details
    ISSN: 1420-9055
    Schlagwort(e): Phosphorus ; mass-balance models ; sedimentation ; error propagation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The empirical adequacy of four phosphorus mass-balance models is evaluated with respect to how the prediction error variance of the corresponding net sedimentation parameters is propagated in the steadystate equations. Using the criterion of minimum propagation error variance (PEV), different groups of lakes can be distinguished for which different empirical equations are used to predict net phosphorus sedimentation. The classification reduced prediction error significantly and also reflected different patterns of sedimentation. Application of this criterion to time-series of individual lakes shows that it is possible to determine a priori whether net annual sedimentation will be better correlated to the annual loading or to the lake content. The correlations depended also on the load/lake content ratio, suggesting that net sedimentation is best viewed as the sum of the partial sedimentation of the load and of the partial sedimentation of the lake content. On average, 25% of the load and 18% of the lake content are sedimented annually. Viewing net phosphorus sedimentation as a function of both the load and the lake content can also explain and predict the well-known cross-sectional correlation between phosphorus retention and water residence time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00877742
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  • 5
    Digitale Medien
    Digitale Medien
    The chemical composition of pine foliage in relation to the population dynamics of the pine beauty moth, Panolis flammea, in Scotland (1989)
    Springer
    Oecologia 78 (1989), S. 251-258 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Panolis flammea ; Pinus ; Nitrogen ; Phosphorus ; Tannins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary This paper reports part of a study to determine why damaging outbreaks of the pine beauty moth, Panolis flammea (D & S) (Lepidoptera: Noctuidae), in Scotland are frequent on lodgepole pine but do not occur on Scots pine, and why outbreaks on lodgepole pine are mainly confined to trees growing in deep unflushed peat. The elongation of shoots and the growth of needles of Scots pine occurred later in the season than did those of lodgepole pine. The foliage of Scots pine generally had a higher level of nitrogen, and consistently had a higher level of phosporus, but had a consistently lower level of tannins than that of lodgepole pine during the period when the larvae were feeding each year. The nitrogen content of the foliage of lodgepole pine growing in an iron pan soil was generally higher than that of lodgepole pine growing in deep peat during the same period but there were no general differences in the phosphorus or tannin contents of lodgepole pine in the 2 soil types. These findings suggest that Scots pine is a more suitable host plant than lodgepole pine and that the foliage of lodgepole pine growing in deep peat is not more suitable than lodgepole pine growing in an iron pan soil. On the basis of the chemical analyses used in this study, it is concluded that the abundance of pine beauty moth in Scotland is not strongly influenced by the nutritional suitability of its host plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00377163
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  • 6
    Digitale Medien
    Digitale Medien
    Physiological determinants of growth rate in response to phosphorus supply in wild and cultivated Hordeum species (1989)
    Springer
    Oecologia 79 (1989), S. 96-105 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Allocation ; Growth ; Phosphorus ; Photosynthesis ; Seed size
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Under favorable nutrition, accessions of the weedy barleygrass (Hordeum leporinum and H. glaucum) had a higher relative growth rate (RGR) than did accessions of cultivated barley (H. vulgare) or its wild progenitor (H. spontaneum). RGR was not positively correlated with the presumed level of soil fertility at the collection site of an accession either within or among species. RGR was reduced more strongly by low-P supply in the progenitor than in the crop or weed, indicating that selection of cultivars to grow in fertile soils had not reduced their potential to grow effectively under low-P conditions. Seed and embryo masses were more important than RGR in determining plant size. Relative differences among assessions in plant size declined with time, because (1) accessions with small seeds had a higher RGR, and (2) RGR of large-seeded accessions declined with time. Absolute growth rate correlated positively with leaf area and negatively with photosynthetic rate per unit leaf area. Under favorable nutrition, maximum photosynthetic rate correlated negatively with leaf length and therefore was higher in the weeds than in the crop or progenitor accessions. P absorption potential did not differ consistently among species but generally increased in response to P stress. Cultivars produced a few tall tillers, whereas weeds and progenitors produced many small tillers. The cultivar had a larger proportion of reproductive tillers, allocated a larger proportion of biomass to grain, and produced larger grains than did the weedy accession. By contrast, the weed began maturing seeds sooner, produced more reproductive tillers, and produced more grains per car and per plant than did the cultivar. The study suggests two major conclusions: (1) A low RGR is not an adaptation to low P supply in annual Hordeum species. (2) Seed size is the major determinant of early plant size between accessions in these Hordeum species under favorable nutrition. However, large seed size indirectly results in a low RGR because of the inverse relationship between plant size and RGR and results in a low photosynthetic rate because of the inverse relationship between leaf size and photosynthesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00378245
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  • 7
    Digitale Medien
    Digitale Medien
    Long-term depletion of calcium and other nutrients in eastern US forests (1989)
    Springer
    Environmental management 13 (1989), S. 593-601 
    Details
    ISSN: 1432-1009
    Schlagwort(e): Acid precipitation ; Biomass nutrients ; Calcium ; Clearcutting ; Magnesium ; Nitrogen ; Phosphorus ; Potassium ; Soil leaching ; Soil nutrients ; Timber harvest ; Weathering ; Whole-tree harvest
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Both harvest removal and leaching losses can deplete nutrient capital in forests, but their combined long-term effects have not been assessed previously. We estimated changes in total soil and biomass N, Ca, K, Mg, and P over 120 years from published data for a spruce-fir site in Maine, two northern hardwood sites in New Hampshire, central hardwood sites in Connecticut and Tennessee, and a loblolly pine site in Tennessee. For N, atmospheric inputs counterbalance the outputs, and there is little long-term change on most sites. For K, Mg, and P, the total pool may decrease by 2%–10% in 120 years depending on site and harvest intensity. For Ca, net leaching loss is 4–16 kg/ha/yr in mature forests, and whole-tree harvest removes 200–1100 kg/ha. Such leaching loss and harvest removal could reduce total soil and biomass Ca by 20%–60% in only 120 years. We estimated unmeasured Ca inputs from rock breakdown, root-zone deepening, and dry deposition; these should not be expected to make up the Ca deficit. Acid precipitation may be the cause of current high leaching of Ca. Although Ca deficiency does not generally occur now in acid forest soils, it seems likely if anthropogenic leaching and intensive harvest removal continue.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01874965
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  • 8
    Digitale Medien
    Digitale Medien
    Localization of calcium and phosphorus in early predentin-matrix components by electron spectroscopic imaging (ESI)-analysis in rat molars (1989)
    Springer
    Cell & tissue research 255 (1989), S. 611-617 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Mantle dentin matrix ; Electron spectroscopic imaging (ESI)-analysis ; Calcium ; Phosphorus ; Dentinogenesis ; Biomineralization ; Rat (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The subcellular distribution of the inorganic elements calcium (Ca) and phosphorus (P) was studied in the first-formed dentin matrix during initial mineralization in neonatal rat molars. This most peripheral matrix region is comprised of a proteoglycan-rich ground substance, interwoven by a collagenous network, matrix vesicles, aperiodic fibrils derived from the dental basal lamina, and apical odontoblastic cell processes. All matrix components may possibly serve as templets for mineral deposition during initial calcification of first-formed mantle dentin and predentin. By means of the very sensitive ESI-analysis we studied the subcellular localization of Ca and P and their possible association with distinct organic extracellular matrix components and odontoblasts. Ca-signals were found in the ground substance, at striated collagen fibrils and plasma membranes of odontoblasts in the cuspal early matrix region, but occurred only sparsely in the ground substance of the more distal matrix region where odontoblast processes attach to aperiodic fibrils of the dental basal lamina. Ca was generally absent in matrix vesicles. In contrast, P-signals were found in matrix vesicles, at aperiodic fibrils and at the plasma membranes of odontoblasts. Ca and P co-localized at striated collagen fibrils (type I or II). These results suggest that striated collagen fibrils might serve as primary deposition sites for calcium phosphate during early biological calcification of organic extracellular macromolecules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00218798
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  • 9
    Digitale Medien
    Digitale Medien
    Environmental modulation of calcium and phosphorus metabolism in embryonic snapping turtles (Chelydra serpentina) (1989)
    Springer
    Journal of comparative physiology 159 (1989), S. 501-508 
    Details
    ISSN: 1432-136X
    Schlagwort(e): Calcium ; Embryos ; Phosphorus ; Turtles ; Water
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Eggs of common snapping turtles (Chelydra serpentina) were incubated on wet (−150 kPa water potential) and dry (−950 kPa) substrates in a laboratory study assessing the effects of the hydric environment on patterns of mobilization of calcium and phosphorus by developing embryos. We found that embryos developing in wet environments withdrew nutrients from their yolk faster, grew more rapidly, and incubated longer than embryos exposed to dry environments. Turtles developing in both environments absorbed calcium from the yolk at similar rates and depleted the yolk of almost its entire reserve of calcium prior to hatching. Calcium withdrawn from the yolk was supplemented with calcium mobilized from the eggshell, but embryos in wet environments obtained substantially more calcium from the eggshell than did those in dry settings. Embryos obtained all of the phosphorus used in skeletogenesis from the yolk, but those incubating in wet environments mobilized phosphorus from this compartment more rapidly than did those in dry settings. Exposing embryonic snapping turtles to wet environments apparently allows them to make more efficient use of the transitory source of calcium in the eggshell than is possible in dry environments. However, the residual yolk in hatchlings from both wet and dry environments contains too little calcium to support the growth of hard and soft tissues in neonates at rates similar to those characterizing the growth phase of development in embryogenesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692422
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  • 10
    Digitale Medien
    Digitale Medien
    Intramolecular, Stoichiometric (Li, Mg, Zn) and Catalytic (Ni, Pd, Pt) Metallo-Ene Reactions in Organic Synthesis [New Synthetic Methods (75)]Dedicated to Professor Elias J. Corey on the occasion of his 60th birthday (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 28 (1989), S. 38-52 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Metallo-ene reaction ; Ene reaction ; Synthetic methods ; Catalysis ; Natural products ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Metallo-ene reactions, hardly recognized until very recently, have experienced a breathtaking development when applied in an intramolecular sense. Efficient regio- and stereoselective magnesium-ene cyclizations have served as a cornerstone for numerous syntheses of structurally diverse natural products (e.g., sesquiterpenes of marine or plant origin, alkaloids, fragrances, insect defense compounds, and a fungitoxin). A brilliant example is the synthesis of the elusive odorant (+)-khusimone which outshines 20 years of work in the field of tricyclovetivane synthesis. Palladium-, platinum-, and nickel-catalyzed versions of the metallo-ene reaction are in a comparatively early stage of exploration, but, nevertheless, reveal intriguing potential. Hence an almost 100% stereospecific C—O→C—;Pd-→ C—C chirality transfer permits simple and selective, cis- or trans-annelation processes. The mild cyclization conditions are compatible with various functional groups, such as nitrogen moieties, which offer interesting perspectives for the preparation of heterocycles (e.g., alkaloids) difficult to obtain by other methods. Carbon monoxide insertion reactions of the cyclized σ-metal intermediates were shown to afford annelated cyclopentanones and cyclopentenones with concomitant stereocontrolled formation of four carbon-carbon bonds. These and other observations, highlighted in this article, provide a platform for further extensions and applications of this powerful method in organic synthesis.
    Zusätzliches Material: 11 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198900381
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  • 11
    Digitale Medien
    Digitale Medien
    Reaction Mechanisms in Heterogeneous Catalysis; C—H Activation as a Case Study (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 28 (1989), S. 135-145 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Reaction mechanisms ; Heterogeneous catalysis ; C-H activation ; Catalysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Heterogeneous catalysis is changing from an empirical art to an exact science. The various methods for the analysis of solids and surfaces, constantly refined by materials science and surface science, seem to be almost unlimited. The increasing availability of atomic resolution microscopy as well as synchrotron radiation allows the characterization of catalyst particles, surface structures, surface processes and surface intermediates. We have learned to determine the surface structure sensitivity of catalytic reactions. Thermodynamic and kinetic data of catalytic reactions are now determined routinely. Isotopic exchange and labeling experiments provide information about reactant-catalyst interactions. How much have we learned through these techniques about the nature or mechanism of heterogeneously catalyzed reactions? The following article attempts to summarize the progress and the problems encountered in mechanistic studies of C—H bond formation and activation in a hydrogen atmosphere as an example for the present state of the understanding of reaction mechanisms in heterogeneous catalysis.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198901353
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  • 12
    Digitale Medien
    Digitale Medien
    Solid Ion Conductors in Heterogeneous Catalysis (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 28 (1989), S. 708-715 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Solid ion conductors ; Ion conductors ; Heterogeneous catalysis ; Conducting materials ; Catalysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The electrochemical measurement of oxygen activity using ion-conducting solid electrolytes (λ-sensors) has become widely known, at least since the application of three-way catalysts in the postcombustion of exhaust gases from spark-ignition engines. However, the use of solid ion conductors is not limited to control devices. There are various other potential applications and numerous problems which can be studied: the formation of oxides in the course of catalytic reactions on metal surfaces, the improvement of selectivity and yield of catalytic reactions, such as the epoxidation of ethylene on silver catalysts and, finally, the cogeneration of electrical energy during oxidation reactions, such as the partial oxidation of methanol to formaldehyde.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198907081
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  • 13
    Digitale Medien
    Digitale Medien
    Cyclizations via Palladium-Catalyzed Allylic Alkylations [New Synthetic Methods (79)] (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 28 (1989), S. 1173-1192 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Cyclization ; Allylic alkylation ; Alkylation ; Synthetic methods ; Palladium ; Catalysis ; C-C coupling ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The history of ring systems in organic chemistry parallels their synthetic accessibility. Transition-metal-catalyzed cyclizations offer a new opportunity to create carbo- and heterocyclic compounds with great facility. Among these methods, allylic alkylations catalyzed by palladium have proven unusually productive because of the extraordinary chemo-, regio-, and diastereoselectivity and the continuing possibility for the development of enantioselectivity. The rules for ring closure differ from those for non-transition-metal-catalyzed reactions. A major benefit is the ability to generate medium (eight-, nine-, ten-, and eleven-membered) and large rings in preference to normal (five-, six- and seven-membered) rings. With the appropriate substrate, efficient macrocyclizations are possible under conditions of normal concentrations. A second major benefit derives from the complementary stereochemistry of the metalcatalyzed substitution (net retention of configuration) compared to non-metal-catalyzed reactions (inversion of configuration). Further, the requirement for the substrate to conform to the transition-metal template may impose a stereochemical preference in the intermediate that ultimately translates into the thermodynamically less stable organic product regardless of the stereochemistry of the starting material. While more work has focused on carbocyclic synthesis, the possibilities for heterocyclic synthesis are just beginning to be tapped. In addition to forming heterocycles by C—C bond formation, use of a heteroatom as a nucleophile has already proven effective for oxygen and nitrogen, with other nucleophiles awaiting investigation. New dimensions for cyclization via allylic alkylation arise by generating the requisite π-allylpalladium intermediates by methods other than palladium(0)-initiated allylic ionizations. In addition, metals other than palladium will clearly expand the possibilities, but as yet remain untapped.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198911731
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  • 14
    Digitale Medien
    Digitale Medien
    Perspectives in Photochromism: A Novel System Based on the 1,5-Electrocyclization of Heteroanalogous Pentadienyl AnionsDedicated to Professor Emanuel Vogel and Professor Klaus Hafner on the occasion of their 60th birthdays (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 28 (1989), S. 413-431 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Photochromism ; Electrocyclic reactions ; Cyclization ; Pentadienyl anions ; Heterocycles ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The molecular process whereby light induces color changes in certain substances, namely photochromism, is currently a topic of active research. Many reactions - mainly monomolecular - have been reexamined in greater detail from the standpoint of photochromism. Those found to be especially suitable for such studies include cis-trans isomerizations, pericyclic reactions, tautomerizations and dissociations. The most important in this group are undoubtedly the electrocyclization reactions. In this paper we present spiro[fluorene-9,1′-[1,8a]-dihydroindolizine] and its bis- and tris-aza analogues as examples of a promising new system with a wide range of variability. Not only the classical uses, but also those in new fields such as frequency doubling of laser radiation, holography or molecular microcircuit chips can now be considered.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198904131
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  • 15
    Digitale Medien
    Digitale Medien
    Über enantiomerenreines (R)-2-Methyl-3-oxo-perhydro-1,4-oxazin (1988)
    Springer
    Monatshefte für Chemie 119 (1988), S. 839-844 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Alpha haloesters ; Enantioselective synthesis ; Heterocycles ; Morpholinones ; Racemization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The synthesis of enantiomerically pure (R)-2-methyl-3-oxo-perhydro-1,4-oxazine is described for the first time. Stereochemical proofs are given and the formation of byproducts is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00809695
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  • 16
    Digitale Medien
    Digitale Medien
    Influence of phenamiphos on the vesicular-arbuscular mycorrhizal symbiosis in Leucaena leucocephala (1988)
    Springer
    Biology and fertility of soils 5 (1988), S. 313-316 
    Details
    ISSN: 1432-0789
    Schlagwort(e): Nematicide ; Phosphorus ; Subleaflet P ; Tropeptic Eutrustox ; Leucaena leucocephala ; VA mycorrhiza ; Glomus aggregatum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Concentrations of phenamiphos ranging from 0 to 40 μrg/g soil were established in a typical Oxisol (Tropeptic Eutrustox), inoculated or uninoculated with Glomus aggregatum. The effect of the nematicide on the development of vesicular-arbuscular mycorrhizal (VAM) symbiosis was evaluated in the greenhouse using Leucaena leucocephala as an indicator host plant. Treatment of soil with phenamiphos did not have a significant influence on the development of mycorrhizal activity measured in terms of subleaflet phosphorus concentrations. Similarly, the nematicide did not have an adverse effect on the level of mycorrhizal colonization or on the P content of shoots, as determined at the time of harvest. However, shoot dry weight was adversely influenced by phenamiphos when the chemical was applied to the uninoculated soil at 20 μg/g soil or higher, and when it was applied to the inoculated soil at 40 μg/g soil. It is concluded that phenamiphos is not likely to influence the growth of Leucaena or its symbiotic association with VAM fungi if the concentrations applied do not exceed levels known to suppress nematodes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00262138
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  • 17
    Digitale Medien
    Digitale Medien
    Calcium and inorganic phosphate secretion of rat ileum in vitro (1988)
    Springer
    Research in experimental medicine 188 (1988), S. 139-149 
    Details
    ISSN: 1433-8580
    Schlagwort(e): Intestinal transport ; 1,25 (OH)2D3 ; Calcium ; Phosphorus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The unidirectional ileal transport of calcium (Ca) and inorganic phosphorus (Pi) of rats was measured in vitro with the modified Ussing technique. Animal preparation included 5/6 nephrectomy and EHDP treatment. They were compared to controls as well as to 1,25 (OH)2D3 supplemented rats. The results show that the ileum is a secretory organ for Ca and Pi, the serosa to mucosa transport (Jsm) exceeds the mucosa to serosa transport (Jms). Ca and Pi transport in sm direction is 1,25 (OH)2D3 independent but exhibits a mutual strong correlation. Our observations together with published data are in favor of mainly paracellular, non electrogenic sm transport of both ions. However, the factor controlling sm transport of Ca and Pi remains unidentified. The mucosa to serosa transport (Jms) in the ileum is low for both ions. Ca ms is stimulated by 1,25 (OH)2D3, Pi ms is unchanged.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01852270
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  • 18
    Digitale Medien
    Digitale Medien
    Activation of alkynes by the dinitrogen complex [CoH(N2)(PPh 3)3] towards catalytic oligomerization and cyclization reactions (1988)
    Springer
    Monatshefte für Chemie 119 (1988), S. 583-589 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Alkynes ; Catalysis ; Dinitrogen complex ; Nitriles ; Pyrimidine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Der Komplex [CoH(N2)(PPh 3)3] katalysiert Oligomerisations- und Cyclisierungsreaktionen von Alkinen unter milden Bedingungen. Die Cyclotrimerisierung von Propinsäureethylester ergibt die drei möglichen Isomeren von Tricarbethoxybenzol; Phenylacetylen reagiert hauptsächlich zu linearen Dimeren (vor allemtrans-PhC≡CCH=CHPh) und Trimeren; lineare Dimere herrschen auch bei 3-Hexin vor, während 1-Octin (mit langer Alkylkette) vorwiegend zu 2-Octin isomerisiert wird. In allen Fällen werden ebenfalls höhere Oligomere gebildet. Außer bei Propinsäureethylester entstehen ebenfalls in geringer Menge hydrierte Dimere (z. B.trans,trans-PhCH=CHCH=CHPh aus Phenylacetylen). Eine neue Art von Cocyclisierungsreaktion mit einem Nitril (NCMe) scheint bei der Bildung (in geringer Ausbeute) von 4,6-Dimethyl-5-phenyl-pyrimidin aus Phenylacetylen vorzuliegen. Alkinole reagieren unter den Versuchsbedingungen nicht.
    Notizen: Abstract The complex [CoH(N2)(PPh 3)3] catalyses oligomerization and cyclization reactions of alkynes under mild conditions. Hence, alkyne cocyclotrimerization to benzene derivatives was mainly observed for ethyl propiolate, affording the three possible isomers of tricarbethoxybenzene; phenylacetylene undergoes mainly linear dimerization totrans-PhC≡CCH=CHPh and trimerization; linear dimers are also the predominant products from 3-hexyne, but 1-octyne (with a long chain) undergoes mainly isomerization to 2-octyne; higher oligomers are also usually formed. Except for ethyl propiolate, hydrogenated dimers are detected in low yields (e.g.trans,trans-PhCH=CHCH=CHPh from phenylacetylene), whereas 3-hexene is formed in considerable yield from 3-hexyne. A novel type of cocyclization reaction with a nitrile (NCMe) appears to occur with phenylacetylene to give (although in low yield) 4,6-dimethyl-5-phenyl-pyrimidine. Alkynols are unreactive under the chosen conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00809210
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  • 19
    Digitale Medien
    Digitale Medien
    Differences in carbon and nutrient fractions among arctic growth forms (1988)
    Springer
    Oecologia 77 (1988), S. 506-514 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Carbohydrate ; Growth form ; Nitrogen ; Phosphorus ; Tundra
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In a survey of 28 plant species of 6 major growth forms from Alaskan tundra, we found no consistent difference among growth forms in the chemical nature of stored reserves except for lichens and mosses (which stored C primarily as polysaccharides) and shrubs (which tended to store C more as sugars than as polysaccharides). Forbs and graminoids showed particularly great diversity in the chemical nature of stored reserves. In contrast, C, N, and P chemistry of leaves was strikingly similar among all species and growth forms. Concentrations of stored reserves of C, N, and P were highest and showed greatest seasonal fluctuations in forbs and graminoids but were relatively constant in evergreen shrubs. From this information, we draw three general conclusions: (1) the photosynthetic function of leaves strongly constrains leaf chemistry so that similar chemical composition is found in all species and growth forms: (2) the chemical nature of storage reserves is highly variable, both within and among growth forms; (3) the concentration and seasonal pattern of storage reserves are closely linked to growth-form and reflect growth-form differences in woodiness, phenology, and relative dependence upon concurrent uptake vs. storage in support of growth.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00377266
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  • 20
    Digitale Medien
    Digitale Medien
    Role of phosphorus and nitrogen in photosynthetic and whole plant carbon gain and nutrient use efficiency in eastern white pine (1988)
    Springer
    Oecologia 77 (1988), S. 25-33 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Photosynthesis ; Nitrogen ; Phosphorus ; Nutrient use efficiency ; Pinus strobus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In white pine (Pinus strobus) seedlings grown in five forest soils from New York State, net photosynthetic capacity (Amax) plant-1 was correlated with total foliar N plant-1 (r 2=0.57), but was more highly correlated with total foliar P plant-1 (r 2=0.82). There was no relationship (r 2〈0.01) between Amax [g leaf]-1 and foliar N [g leaf]-1 for the pooled data set, but there was a significant (P〈0.001), but weak (r 2=0.20) positive relationship between Amax [g leaf]-1 and foliar P [g leaf]-1 across all soils. However, within two of the five soils leaf N concentration was a significant (P〈0.05) determinant of photosynthetic capacity. Due to differences in soil nutrient availabilities a large range in foliar P:N ratio (0.02–0.15) was observed, and the proportion of leaf P:N appeared to control Amax [g leaf N]-1. Whole plant nitrogen (NUE) and phosphorus (PUE) use efficiencies were well correlated with whole plant P:N ratio. In addition, NUE was well correlated with Amax [g leaf N]-1 and PUE was well correlated with Amax [g leaf P]-1. However, NUE was not well correlated with PUE, and Amax [g leaf N]-1 was not well correlated with Amax [g leaf P]-1. These results indicated that P and/or N limitations were important components of photosynthetic nutrient relations in white pine grown in these five soils and suggest that both P and N and their proportions should be considered in analyses of photosynthesis-nutrient relations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00380920
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  • 21
    Digitale Medien
    Digitale Medien
    Eutrophication of Buttermilk Bay, a cape cod coastal embayment: Concentrations of nutrients and watershed nutrient budgets (1988)
    Springer
    Environmental management 12 (1988), S. 539-553 
    Details
    ISSN: 1432-1009
    Schlagwort(e): Coastal embayments ; Eutrophication ; Nitrogen ; Phosphorus ; Coastal lagoons ; Groundwater ; Septic tanks ; Nutrient loading
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Nutrient concentrations in Buttermilk Bay, a coastal embayment on the northern end of Buzzards Bay, MA, are higher in the nearshore where salinities are lower. This pattern suggests that freshwater sources may contribute significantly to nutrient inputs into Buttermilk Bay. To evaluate the relative importance of the various sources we estimated inputs of nutrients by each major source into the watershed and into the bay itself. Septic systems contributed about 40% of the nitrogen and phosphorus entering the watershed, with precipitation and fertilizer use adding the remainder. Groundwater transported over 85% of the nitrogen and 75% of the phosphorus entering the bay. Most nutrients entering the watershed failed to reach the bay; uptake by forests, soils, denitrification, and adsorption intercepted two-thirds of the nitrogen and nine-tenths of the phosphorus that entered the watershed. The nutrients that did reach the bay most likely originated from subsoil injections into groundwater by septic tanks, plus some leaching of fertilizers. Buttermilk Bay water has relatively low nutrient concentrations, probably because of uptake of nutrients by macrophytes and because of relatively rapid tidal flushing. Annual budgets of nutrients entering the watershed showed a low nitrogen-to-phosphorus ratio of 6, but passage of nutrients through the watershed raised N/P to 23, probably because of adsorption of PO4 during transit. The N/P ratio of water that leaves the watershed and presumably enters the bay is probably high enough to maintain active growth of nitrogenlimited coastal producers. There is a seasonal shift in N/P in the water column of Buttermilk Bay. N/P exceeded the 16∶1 Redfield ratio during midwinter; the remainder of the year N/P fell below 16∶1. This suggests that annual budgets do not provide sufficiently detailed data with which to interpret nutrient-limitation of producers. Further, some idea of water turnover is also needed to evaluate impact of loading rates. Urbanization of watersheds seems to increase loadings to nearshore environments, and to shift the nutrient loadings delivered to coastal waters to relatively high N-to-P ratios, potentially stimulating growth of nitrogen-limited primary producers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01873266
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  • 22
    Digitale Medien
    Digitale Medien
    Phosphorus and pH relationships in an andic soil with surface and incorporated organic amendments (1988)
    Springer
    Plant and soil 107 (1988), S. 273-278 
    Details
    ISSN: 1573-5036
    Schlagwort(e): available P. organic amendments ; pH ; Phosphorus ; residue management Volcanic ash-influenced soils
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Mission silt loam, (coarse-silty, mixed frigid Andic Fragiochrepts) is a forest soil in the Pacific Northwest which has a weathered ash horizon derived from volcanic eruptions in the Cascade Mountain Range. The major production problem for this soil is P fixation due to the weathered volcanic ash. Alternatives to large additions of fertilizer P are considered important in management of this and related soils. The objective of this work was to study the infuence of organic amendments on soil pH and extractable P in Mission soil. Alfalfa, (Medicago sativa L.) mixed conifer bark or sawdust was added at 4.8% w/w soil as a surface or incorporated treatment. In incubation experiments, both extractable P and soil pH were significantly increased over time for both surface and incorporated amendments. The majority of P mineralized from surface applied alfalfa remained in the surface 0–2 cm of the soil regardless of incubation period. Conversely, a uniform increase in P occurred throughout the 18 cm soil depth when sawdust was surface applied. The change in extractable P with sawdust addition was equivalent to 61 mg P kg−1 soil as soluble inorganic material. Soil pH increased rapidly in proximity to surface applied alfalfa while bark and sawdust affected the soil increasingly with time regardless of placement.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02370557
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  • 23
    Digitale Medien
    Digitale Medien
    Specific activity measurements to determine phosphorus turnover in bluegill, Lepomis macrochirus (1988)
    Springer
    Hydrobiologia 157 (1988), S. 3-11 
    Details
    ISSN: 1573-5117
    Schlagwort(e): Phosphorus ; P-32 ; bluegill ; biological turnover constant ; radioactive tracer study ; specific activity measurements
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The biological turnover constant for phosphorus was determined in muscle and five other sections of bluegill. Bluegill of average weight 121 g were maintained in a large flowthrough system at 22°–16°C and fed worms, Eisenia foetida, at two feeding levels, ad lib. (which averaged 2.6 g/d per 100-g fish, wet weight), and 1.5 g/d per 100-g fish. The daily phosphorus intakes at the two levels per 100-g fish were 3.1 and 1.8 mg. The average phosphorus concentration was 2.4 mg/g in muscle and 15.4 mg/g in the whole fish. Worm food was spiked with P-32 at increasing daily increments to balance radioactive decay. The radioactive worms were fed daily to the bluegill during the P-32 accumulation period of 51 days. For the next 28 days of depuration, nonradioactive worms were fed. Sets of three bluegill were collected at approximately weekly intervals, sectioned and analyzed for P-32 and phosphorus. All data were reported as specific activity in tissue relative to specific activity in feed, with P-32 count rates corrected for its 14.3-day half life. Phosphorus turnover constants were obtained by three approaches: (1) from the relative specific activity measured near steady state; (2) by fitting an equation for a 1-compartment model to the accumulation and depuration data; and (3) by fitting an equation for a simplified 2-compartment model to the depuration data. The biological turnover constant calculated with all three approaches was 0.004 d−1 for phosphorus in muscle of bluegill fed ad lib.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00008804
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  • 24
    Digitale Medien
    Digitale Medien
    Lake Kinneret phytoplankton: Response to N and P enrichments in experiments and in nature (1988)
    Springer
    Hydrobiologia 166 (1988), S. 65-75 
    Details
    ISSN: 1573-5117
    Schlagwort(e): Phytoplankton ; Subtropical Lake ; Nitrogen ; Phosphorus ; Nutrient enrichment ; Chlorophyta ; Flagellates ; Cyanophyta ; Bacillariophyta
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A series of water samples from Lake Kinneret was supplemented with 100 µM N (as NH4 or as NO3 and/or 10 µM orthophosphate-P. The yield of phytoplankton both as chlorophyll and in cell numbers of major species was determined after a two-week incubation. During these experiments, some of the algae present initially never multiplied (e.g. Peridinium and Peridiniopsis spp. Cryptomonas spp., Rhodomonas spp. and Crysochromulina parva); others e.g. Anomoeoneis exilis, Synedra sp., Chlamydomonas sp., Elakatothrix gelatinosa), undetected in the original sample, grew out during the incubation. Chlorophyte species (the majority of commonly observed forms in the lake) responded most readily to added nutrients. The results of these enrichment experiments were related to the long-term record of phytoplankton populations observed in the lake and suggest that through summer and fall, when ambient levels of both P and N are minimal, P was generally, but not always, the most limiting nutrient for algal growth. In the spring, after the decline of the Peridinium bloom, P appeared to be limiting the growth of Chlorophyta. Although most algal species grew equally well on NH4 or NO3, some species appeared to respond preferentially either to the former (Coelastrum, Chodatella) or to the latter (Chroococcus, Anomoeoneis) source of N.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00017484
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  • 25
    Digitale Medien
    Digitale Medien
    Phosphorus in soil, water and sediment: an overview (1988)
    Springer
    Hydrobiologia 170 (1988), S. 19-34 
    Details
    ISSN: 1573-5117
    Schlagwort(e): Phosphorus ; mineral ; soil ; sediment ; sorption ; transport
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The geochemistry, availability and abundance of different forms of phosphorus in soil, water and sediments are reviewed. The present knowledge of phosphorus pathways in ecosystems and their regulation is discussed. In a drainage basin, anthropogenic phosphorus is brought into the system mainly as fertilizers and detergents. Sewer systems and outwash processes transfer the phosphorus from the terrestrial environment to the aquatic part of the ecosystem where an accumulation occurs in the sediments of the watercourse. A great part of the phosphates in soil is sorbed to soil particles or incorporated into soil organic matter. The release and export of phosphorus from uncultivated soil is a function of the geology and soil composition, but also of the air temperature, precipitation and the hydrological condition, pH etc. The solubility of phosphates is controlled by either sorption-desorption or precipitation-dissolution reactions depending on the environment in the soil or sediments. In soil and sediments with large amounts of iron and aluminium hydrous oxides, sorption-desorption reactions are largely responsible for determining the level of orthophosphate in the solution at equilibrium. Algal availability of phosphorus associated with soil-derived materials present in aquatic systems deserves more research. In addition, processes responsible for transport of phosphorus from cropland to aquatic systems and chemical and microbial transformations of phosphorus in lakes and streams deserve more attention.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00024896
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  • 26
    Digitale Medien
    Digitale Medien
    Dehydrogenative condensation of monohydrosilanes yielding disilanes in the presence of platinum complex catalysts (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 2 (1988), S. 91-92 
    Details
    ISSN: 0268-2605
    Schlagwort(e): Catalysis ; dehydrogenation ; hydrosilane ; disilane ; platinum complex ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Dimethylphenylsilane was catalytically dehydrogenated and condensed in the presence of platinum complexes to give 1,1,2,2-tetramethyl-1,2-diphenyl-disilane.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aoc.590020114
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  • 27
    Digitale Medien
    Digitale Medien
    Electron-Transfer Chain Catalysis in Organotransition Metal ChemistryDedicated to Professor Jean Tirouflet (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 27 (1988), S. 643-660 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Catalysis ; Electrocatalysis ; Chain catalysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Parallel to organic electrocatalysis, the field of organotransition metal electrocatalysis has developed explosively since 1980. The theoretical and experimental foundations established by Feldberg in 1971 (ECE mechanism) have been applied, using fast electrochemical techniques, to various organometallic reactions such as isomerization, ligand exchange, chelation, decomplexation, and CO insertion and extrusion. Most of the work performed to date concerns ligand exchange reactions of N-donors and P-donors in mononuclear compounds, initiated by oxidants (or anodes) and of carbonyls and P-donors in clusters, initiated by reducing agents (or cathodes). The preparative aspects of electrocatalysis have already been impressively developed in cluster chemistry and indicate that the technique is extremely useful. This review first delineates the principles and characteristics of electrocatalysis applied in organotransition metal chemistry, and then, after outlining the choice of efficient initiating reagents, goes on to describe the systems up to August 1986.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198806431
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  • 28
    Digitale Medien
    Digitale Medien
    Carbon Dioxide as an Alternative C1 Synthetic Unit: Activation by Transition-Metal Complexes (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 27 (1988), S. 661-678 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Carbon dioxide ; C1 synthetic unit ; Transition metals ; C-C coupling ; Homogeneous catalysis ; Catalysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The carbon dioxide molecule has been of limited importance as a synthetic unit in organic chemistry. When it is coordinated to transition metals, however, completely new possibilities arise; CO2 can bond to metal complexes in a variety of ways and can enter into insertion and coupling reactions, or become catalytically attached to other substrates. The formation of C—C bonds between carbon dioxide and unsaturated hydrocarbons under conditions of homogeneous catalysis makes available new synthetic routes to industrially interesting organic compounds.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198806611
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  • 29
    Digitale Medien
    Digitale Medien
    Molecular Organometallic Chemistry on Surfaces: Reactivity of Metal Carbonyls on Metal Oxides (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 27 (1988), S. 1127-1144 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Organometallic compounds ; Surface chemistry ; Carbonyl ligands ; Metal oxides ; Catalysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Metal carbonyls react on metal oxide surfaces to give a wide range of structures analogous to those of known compounds. The reactions leading to formation of surface-bound metal carbonyls are explained by known molecular organometallic chemistry and the functional group chemistry of the surfaces. The reaction classes include formation of acid-base adducts as the oxygen of a carbonyl group donates an electron pair to a Lewis acidic center; nucleophilic attack at CO ligands by basic surface hydroxyl groups or O2⊖ ions; ion-pair formation by deprotonation of hydrido carbonyls to give carbonylate ions; interaction of bifunctional complexes with surface acid-base pair sites such as [Mg2⊕O2⊖]; and oxidative addition of surface hydroxyl groups to metal clusters. The reactions of surface-bound organometallic species include redox condensation and cluster formation on basic surfaces (paralleling the reactions in basic solution) as well as oxidation of mononuclear metal complexes and oxidative fragmentation of metal clusters by reaction with surface hydroxyl groups. Most supported metal carbonyls are unstable at high temperatures, but some, including osmium carbonyl cluster anions on the basic MgO surface, are strongly stabilized in the presence of CO and are precursors of catalysts for CO hydrogenation at 550 K.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198811271
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  • 30
    Digitale Medien
    Digitale Medien
    High Oxidation State Organometallic Chemistry, A Challenge - the Example of RheniumSecond Essay on Organometallic Chemistry. First Essay: W. A. Herrmann, Comments Inorg. Chem. 7 (1988) 73.Dedicated to Professor Hans Bock on the occasion of his 60th birthday (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 27 (1988), S. 1297-1313 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Rhenium ; Catalysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Homogeneous catalysis as the major industrial outlet of organometallic basic research has been enjoying great benefit from organotransition metal species that promote bond forming between hydrocarbon fragments. Most of the commercially important processes that serve to produce large-volume organic feedstock chemicals such as linear α-olefins (Shell Higher Olefins Process), linear aldehydes (hydroformylation), acetaldehyde (Wacker-Hoechst), acetic acid (Monsanto), adiponitrile (DuPont hydrocyanation of butadiene) operate at low-valent metal centers. It is thus hardly surprising that by far the most part of organometallic research during the past few decades has been directed towards an understanding and the improvement of these catalytic reactions as well as towards the related stoichiometric chemistry. As a matter of consequence, our present knowledge on high-valent organotransition metal compound is comparatively shallow, nor do we know much about the chemical relationship and interconvertability of high and low oxidation states within a given class of compounds. In this article I want to point out some ostensibly challenging perspectives of future organometallic research by describing a novel class of high oxidation state organorhenium compounds as well as by speculating on possible generalizations for other transition metals.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198812971
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  • 31
    Digitale Medien
    Digitale Medien
    Uniform Heterogeneous Catalysts: The Role of Solid-State Chemistry in their Development and DesignBased, in part, on the Hund-Klemm Lecture given at the Max Planck Institute for Solid State Research, Stuttgart (20 May 1987), and on seminars given at the Institute of Fundamental Chemistry, Kyoto (14 June, 1988), the Fritz Haber Institute of the Max-Planck-Gesellschaft, Berlin (12 March 1987), and the University of California, Berkeley (19 April 1988). (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 27 (1988), S. 1673-1691 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Heterogeneous catalysis ; Solid-state reactions ; Catalysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Heterogeneous catalysts are generally assumed to be multiphasic and multicomponent; many of them are, and this is one of the resons why disentangling the factors that govern their mode of action is so difficult. But there is a large class of heterogeneous catalysts where the solid is monophasic and where the activity may be envisaged as being dispersed in a spatially uniform fashion throughout its bulk. This is true both of zeolites and many other microporous catalysts on the one hand, and of certain mixed metal oxides, where the non-stoiohiometry is inextricably mingled with the catalysis, on the other. By recognizing this broad classification numerous operational advantages follow: the performance of existing catalysts and the design of those yet to be prepared can be placed on a rational footing; moreover, the myriad techniques of solid-state chemistry and physics, often regarded as inapplicable to the subtle and special problems of surface chemistry, are seen to be of direct relevance as probes for the structure and properties of proven uniform heterogeneous catalysts as well as for the synthesis and development of new ones. This review, which draws analogies with and lessons from the chemistry of enzyme catalysts, focuses largely on the catalytic conversions of hydrocarbons over zeolites, clays, microporous AlPO4 and a wide range of metal oxides.
    Zusätzliches Material: 32 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198816731
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  • 32
    Digitale Medien
    Digitale Medien
    Zeolites: Catalysts for Organic SynthesesDedicated to Professor Helmut Dörfel on the occasion of his 60th birthday (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 27 (1988), S. 226-246 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Zeolites ; Catalysis ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Zeolites have proved to be valuable technical catalysts in petrochemistry and in oil processing. The characteristic properties of zeolites, such as acidity, shape-selectivity and thermal stability also enable them to be used for highly selective synthesis in the fields of chemical intermediates and fine chemicals. This interesting area of application has grown continuously in recent years. The present article summarizes the various standard types of reaction involved in organic syntheses which can be catalyzed by zeolites; these include, inter alia, electrophilic and nucleophilic substitution reactions, isomerization of double bonds and carbon skeletons, as well as addition, elimination and hydrogenation reactions.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198802261
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  • 33
    Digitale Medien
    Digitale Medien
    Contributions to Organo-Nickel ChemistryIncluding unpublished results by A. Aradi, O. Behrens, H. Kuhn, T. Leven, J. Neuffer, J. Monkiewicz, K. R. Pörschke, L. Stehling, and K. H. Walter and unpublished crystal structure determinations by C. Krüger, E. Raabe, and Y.-H. Tsay, and model calculations by K. Angermund. The preceding page shows Figure 19 of this article. (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 27 (1988), S. 185-206 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Organonickel compounds ; Polymerization ; Hydrogenation ; Homogeneous catalysis ; Catalysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: One hundred years of organonickel chemistry have generated a wealth of new knowledge and a history of examples of accidental discoveries which have finally led to industrial applications. The historical development is associated with the names of Mond, Sabatier, Reppe and Ziegler and, with the methods and techniques available today, many of the original discoveries and unsolved problems are attracting renewed attention. For example, 70 years were to go by before a synthesis first conceived by Sabatier could finally be realized. The path leading from nickel-catalyzed hydrogenation to highly enantioselective homogeneous catalysts is one of the contributions to organonickel chemistry which is described here.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198801851
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  • 34
    Digitale Medien
    Digitale Medien
    Ketenimine Complexes from Carbene Complexes and Isocyanides: Versatile Building Blocks for Carbocycles and N-Heterocycles [New Synthetic Methods (74)]Dedicated to Professor Ernst Otto Fischer on the occasion of his 70th birthday (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 27 (1988), S. 1456-1467 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Ketenimines ; Carbene ligands ; Isocyanides ; Carbocycles ; Heterocycles ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ketenimine complexes are readily available in great variety by reaction of isocyanides with carbene complexes. They have proven to be useful building blocks in new synthetic approaches to carbocyclic and N-heterocyclic four-, five-, and six-membered rings. The reactions involve new metal-induced bond formation patterns of the ketenimine ligands, which can be influenced across a wide range by varying the following five parameters: the metal, the ligands, and the three substituents on the N=C=C unit.
    Zusätzliches Material: 8 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198814561
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  • 35
    Digitale Medien
    Digitale Medien
    Phosphaalkynes - Syntheses, Reactions, Coordination Behavior [New Synthetic Methods (73)]Phosphorus Compounds with Unusual Coordination, Part 30. Part 29: [119]. (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 27 (1988), S. 1484-1508 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Phosphaalkynes ; Synthetic methods ; Phosphorus-carbon compounds ; Multiple bonds ; Heterocycles ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Organophosphorus compounds have been applied in two ways in chemical synthesis. They can either be used as a reagent in a step of the synthesis (for example, in the Wittig reaction) or they can be incorporated directly into the target molecule. This second application, in particular, has expanded greatly in the last few years with the preparation of low-coordination phosphorus compounds. These include the phosphaalkynes, which are of great interest to organic and inorganic chemists. Phosphaalkynes have been employed in the synthesis of heterocyclic compounds, phosphaarenes and their valence isomers, and polycyclic compounds. Further applications have been the use of phosphaalkynes as new ligand systems in complex chemistry and their cyclooligomerization with organometallic reagents. While the chemical properties of phosphaalkynes have little in common with those of nitriles, they are in many ways very similar to those of the isoelectronic acetylenes.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198814841
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  • 36
    Digitale Medien
    Digitale Medien
    Change of water structure by solvents and polymers Part 4: Albumin-water solutions with acetylsalicylic, hydrochloric and ascorbic acid, lysine- and ammonium chloride and with dextrane and sorbit (1987)
    Springer
    Colloid & polymer science 265 (1987), S. 908-910 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Key words ; Viscosity ; water structure ; albumin ; acetyisalicylic acid ; lysine chloride ; ascorbic acid ; dextrane ; sorbit
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Viscosity measurements were made in the temperature range of 10 °–40 °C. The equationν=ν o exp(B/(T-T o )) was used with the parameterT 0 as “structure indicator”, which is called the “limiting temperature”. For instance, hydrocarbons, as liquids with “quasifree” molecules, haveT 0=O; water as a highly structured liquid hasT 0= 140–150 K. The polymer investigated was ovalbumin in aqueous solution in a concentration comparable to that of blood. Acetylsalicylic acid produces a protein conformation which breaks the water structure in solution at a pH of within the in vivo region. The question of whether only the acidity determines the water structure breaking properties of the protein is investigated by acidifying albumin-water solutions with hydrochloric acid, lysine chloride and ascorbic acid. All these acids exhibit similar effects. A stronger influence is observed for ammonium chloride. Its interaction with ovalbumin produces a strong structure-breaking effect. The most powerful water structure breaker in albumin-water solutions is dextrane. In a concentration of 10 % it changes the polymer conformation so that the water structure is broken to such an extent that the solution behaves as an almost “quasifree” liquid withT 0=O.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01421820
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  • 37
    Digitale Medien
    Digitale Medien
    A new convenient synthetic method for 3,4-diaryl-2,6-piperidinediones (1987)
    Springer
    Monatshefte für Chemie 118 (1987), S. 987-991 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Heterocycles ; Piperidinediones
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Durch saure Hydrolyse der entsprechenden Ethyl-3,4-diaryl-4-cyanobutyrate wurden in einem Schritt (Eintopfreaktion) die 3,4-Diaryl-2,6-piperidindione dargestellt.
    Notizen: Abstract A one-pot reaction for the preparation of 3,4-diaryl-2,6-piperidinediones through acid hydrolysis of the corresponding ethyl 3,4-diaryl-4-cyanobutyrates is described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00815326
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  • 38
    Digitale Medien
    Digitale Medien
    Microbial activity and nutrient dynamics in earthworm casts (Lumbricidae) (1987)
    Springer
    Biology and fertility of soils 5 (1987), S. 230-234 
    Details
    ISSN: 1432-0789
    Schlagwort(e): Earthworm casts ; Microbial respiration ; Microbial biomass ; Nitrogen ; Phosphorus ; Aporrectodea caliginosa
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Microbial respiration, microbial biomass and nutrient requirements of the microflora (C, N, P) were studied in the food substrate (soil taken from the upper 3 cm of the mineral soil of a beech wood on limestone), the burrow walls and the casts of the earthworm Aporrectodea caliginosa (Savigny). The passage of the soil through the gut caused an increase in soil microbial respiration of about 90% over a 4-week period. Microbial biomass was increased only in freshly deposited casts and decreased in aging faeces to a level about 10% lower than in soil. Microbial respiration of the burrow walls was only increased over a shorter period (about 2 weeks). The microflora of the soil and the burrow walls was limited by P, whereas in earthworm casts, microbial growth was limited by the amount of available C. In aging faeces the P requirement of the microflora increased and approached that of the soil. Immobilization of phosphate in earthworm casts is probably caused by mainly abiotic processes. C mineralization by soil microflora fertilized with glucose and P was limited by N, except in freshly deposited casts. Ammonium, not nitrate, was responsible for this process. N dynamics in earthworm casts are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00256906
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  • 39
    Digitale Medien
    Digitale Medien
    Smooth approximation of data on the sphere with splines (1987)
    Springer
    Computing 38 (1987), S. 177-184 
    Details
    ISSN: 1436-5057
    Schlagwort(e): 65D07 ; Key words ; Approximation over the sphere ; tensor product splines ; spherical harmonics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Wir konstruieren eine berechenbare Funktion, die auf der Kugeloberfläche definiert und mindestensC 1 ist und die eine vorgegebene Datenmenge approximiert. Die Konstruktion beruht auf Tensorprodukt-Spline-Basisfunktionen; an den Polen des sphärischen Koordinatensystems benutzen wir modifizierte Basisfunktionen in Analogie zu sphärischen harmonischen Entwicklungen, um die Glattheit an diesen Stellen zu bewahren. Konvergenzexperimente mit Verfeinerung der Gitter wurden durchgeführt und die Ergebnisse mit ähnlichen in der Literatur verglichen. Die Verwendung stückweiser Approximationen mit lokalen Basisfunktionen wird der Approximation mit sphärischen Harmonischen gegenübergestellt und die Approximationsgüten werden verglichen.
    Notizen: Abstract A computable function, defined over the sphere, is constructed, which is of classC 1 at least and which approximates a given set of data. The construction is based upon tensor product spline basisfunctions, while at the poles of the spherical system of coordinates modified basisfunctions, suggested by the spherical harmonics expansion, are introduced to recover the continuity order at these points. Convergence experiments, refining the grid, are performed and results are compared with similar results available in literature. The approximation accuracy is compared with that of the expansion in terms of spherical harmonics. The use of piecewise approximation, with locally supported basisfunctions, versus approximation with spherical harmonics is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02240181
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  • 40
    Digitale Medien
    Digitale Medien
    Reducing fertilizer requirements for hybrid squash (Cucurbita maxima L.) with localized applications of phosphorus and potassium and use of partially acidulated phosphate rock (1987)
    Springer
    Nutrient cycling in agroecosystems 13 (1987), S. 169-180 
    Details
    ISSN: 1573-0867
    Schlagwort(e): Phosphorus ; potassium ; fertilizer placement ; triple-superphosphate ; partially acidulated phosphate rock ; hybrid squash ; Cucurbita maxima L.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Two experiments examined options for reducing the inputs of P and K fertilizers for hybrid squash (Cucurbita maxima L.) at Pukekohe, New Zealand. The first experiment examined the effects of elevating the NaHCO3-soluble P from 32 to 130 mg kg−1 and the exchangeable K from 140 to 350 mg kg−1 within strips from 0 to 0.75 m around rows of hybrid squash planted 1.5 m apart. From both P and K, crop yield increased as the width of the fertilized strip was increased up to 0.25 m, while wider fertilized strips had no further effect. These results followed similar effects on plant dry matter and tissue P or K concentration during early growth, and are explained in terms of the P and K accumulation by the crop, the decline during growth of the sensitivity of the crop to soil P and K fertility associated with declining rates of P and K uptake per unit length of root. Implications for fertilizer management for hybrid squash are also discussed. The second experiment compared the effects of partially acidulated phosphate rock and triple-superphosphate on soil P fertility, growth and yield of hybrid squash. Partially acidulated phosphate rock had smaller effects than those of triple-superphosphate on NaHCO3-soluble P levels in the soil, plant dry weight and tissue P concentration soon after emergence, and subsequently crop yield. On average, partially acidulated phosphate rock increased crop yield by about 70% of that following the application of the same quantity of P as triple-superphosphate. This lower effectiveness of partially acidulated phosphate rock for hybrid squash is explained in terms of its lower solubility and hence smaller effect on NaHCO3-soluble P in the soil during early growth, when the crop is most sensitive to soil P fertility.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01064830
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  • 41
    Digitale Medien
    Digitale Medien
    The increase in skin 7-dehydrocholesterol induced by an hypocholesterolemic agent is associated with elevated 25-hydroxyvitamin D3 plasma level (1987)
    Springer
    Pflügers Archiv 410 (1987), S. 165-168 
    Details
    ISSN: 1432-2013
    Schlagwort(e): Cholesterol ; 1,25 Vitamin D3 ; Calcium ; Phosphorus ; Calcemia ; Hypocholesterolemia ; 7-Dehydrocholesterol reductase ; Epidermis ; Rat UV radiation ; Skin vitamin D3 synthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Vitamin D3 is generated in skin by UV irradiation of 7-dehydrocholesterol (7-DEHC). Whether the 7-DEHC amount in skin affects vitamin D3 formation, and thereby the plasma level of 25-hydroxyvitamin D3 (25[OH]D3) is not known. In the present work we report on the influence on vitamin D and Ca metabolism of a new hypocholesterolemic agent, HCG-917 (0-2-[hydroxy-3-]N′-(2-chlorophenyl)-N-piperazinyl-1-[propyl]-4-chloro-benz-aldoxim-hydrochloride) which inhibits 7-DEHC reductase and thereby increases skin 7-DEHC. Rats were treated with HCG 917 (0.3 and 5.0 mg/kg, orally) for 13 days. HCG 917 caused a dose-dependent decrease in cholesterol and concomitant accumulation of 7-DEHC in plasma and skin. In skin, 7-DEHC was: control: 1.05±0.20; HCG 917, 0.3 mg/kg: 1.41±0.22; HCG 917, 5.0 mg/kg: 2.35±0.35 mg/g. At a dose of 0.3 mg/kg, HCG 917 had no significant influence on the plasma level of neither 25(OH)D3 nor 1,25(OH)2D3. However, at a dose of 5.0 mg/kg, HCG 917 induced a significant increase in plasma 25(OH)D3 (control: 36.2±2.2; HCG 917 5.0 mg/kg: 57.6±6.5 nmol/l) and a slight but not significant rise in 1,25(OH)2D3. Calcium balance studies indicated that HCG 917 did not influence intestinal Ca absorption nor urinary Ca excretion. At a dose of 5.0 mg/kg HCG 917 slightly induced a decrease in total plasma Ca. In conclusion, HCG 917 treatment can induce a significant rise in skin 7-DEHC with an increase in plasma 25(OH)D3. These results suggest that variation in the skin level of 7-DEHC can directly influence the cutaneous production of vitamin D3 and thereby the vitamin D status of the organism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00581910
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  • 42
    Digitale Medien
    Digitale Medien
    The effect of nitrogen and phosphorus addition on the growth, reproduction, and nutrient dynamics of two ericaceous shrubs (1987)
    Springer
    Oecologia 71 (1987), S. 541-547 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Ericaceae ; Nitrogen ; Phosphorus ; Deciduous ; Evergreen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Aboveground growth, reproduction, and foliar nitrogen and phosphorus contents of two ericaceous shrub species were compared over two seasons in (a) an undisturbed shrub bog (pocosin), and (b) a factorial fertilization design in which three levels each of nitrogen and phosphorus were added in all possible combinations. One species, Zenobia pulverulenta, is deciduous whereas the other species, Lyonia lucida, is evergreen. In the nutrient-poor undisturbed pocosin the two species exhibited similar foliar nitrogen and phosphorus concentrations and aboveground growth rates. Neither species flowered. In response to nutrient-addition Zenobia increased growth rates more than Lyonia. Foliar phosphorus concentrations of both species increased in response to enhanced phosphorus availability. in the first season neither species flowered in any treatment. In the second season Zenobia flowered only in the fertilized plots, with the most flowering in the high phosphorus treatments. I conclude that, by virtue of high growth rates and efficient use of nutrients and despite differences in leaf phenology and morphology, both Lyonia and Zenobia are successful in a competitive community under conditions of extremely low phosphorus availability. However, unlike Lyonia, Zenobia can take advantage of temporarily increased nutrient availability, which occurs following fire in the pocosin, to increase growth and reproduction.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00379294
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  • 43
    Digitale Medien
    Digitale Medien
    Resorption of foliar nutrients in a regenerating southern Appalachian forest (1987)
    Springer
    Oecologia 73 (1987), S. 268-271 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Foliar nutrients ; Resorption ; Succession ; Nitrogen ; Phosphorus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Leaves were sampled in a successional, southern Appalachian forest to estimate autumn foliar nutrient dynamics. Resorption of N and P in a successional forest equaled, or exceeded, resorption estimates for a more mature control forest. Foliar nutrient leaching was not sufficient to account for changes in autumn leaf N, P, Ca and Mg concentrations. The resorption process conserves nutrients by reducing nutrient losses from leaching and litter-fall, thereby closing the nutrient cycle in successional forests. We hypothesize that rapid recovery of primary productivity early in forest regeneration is the result of maximum nutrient resorption of limiting nutrients. Implications of these results for successional nutrient cycling theory are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00377517
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  • 44
    Digitale Medien
    Digitale Medien
    Bioassays of nutrient limitation in a tropical rain forest soil (1987)
    Springer
    Oecologia 74 (1987), S. 370-376 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Costa Rica ; Miconia ; Piper ; Nitrogen ; Phosphorus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Six speices of shrubs and one large herb with contrasting life history patterns were used as bioassays of nutrient availability in a Costa Rican lowland rain forest soil. Growth responses of the herb (Phytolacca rivinoides, Phytolaccaceae) confirmed soil measurements indicating high availability of N and potentially limiting levels of P, K, Mg and Ca. Growth responses of the shrub species (Miconia spp., Melastomataceae and Piper spp., Piperaceae) to a complete nutrient fertilizer were generally less than that of Phytolacca. Lack of a strong shrub response to +P fertilization is probably due to mycorrhizal associations and slower growth rates of woody species. In general, increased growth did not occur at the expense of phenolic production in the leaves. The results emphasize that assessment of specific nutrient limitations to plant growth vary depending on species selected for the bioassay, even among species from the same community.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00378932
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  • 45
    Digitale Medien
    Digitale Medien
    Differential effects of prostaglandins on mesenteric and cerebral arteries isolated from premature newborn baboons (1987)
    Springer
    European journal of pediatrics 146 (1987), S. 61-62 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Key words ; Prostaglandin E1, E2, F2α and I2 (prostacyclin) ; Cerebral artery ; Mesenteric artery ; Baboons/primate animals ; Premature newborns
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Responses to prostaglandins (PGs) E1, E2, F2α and I2 at a wide range of concentrations were compared in the cerebral and mesenteric arteries isolated from premature newborn baboons. PGE1 at low concentrations relaxed the cerebral artery but not the mesenteric artery. PGI2 produced a relaxation of similar magnitude in both arteries. PGF2α in high concentrations produced a much greater contraction in the mesenteric artery than in the cerebral artery. Thus, during the perinatal stage, the baboon cerebral artery has distinctive PG-reactivity compared to the extracerebral artery. Clinical use of PGE1 or indomethacin may result in circulatory derangement or redistribution of blood flow in the cerebral and mesenteric circulations, and may produce side effects of these drugs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00647287
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  • 46
    Digitale Medien
    Digitale Medien
    Mechanical properties and molecular mobility in oriented polyolefines (1987)
    Springer
    Colloid & polymer science 265 (1987), S. 220-225 
    Details
    ISSN: 1435-1536
    Schlagwort(e): Fibers ; elastic modulus ; correlation time ; molecularmobility ; orientation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The static modulus of elasticity (E) and the correlation time of rotation (τ c ) of 2,-2,6,6-tetramethylpiperidine-1-oxyl are studied as a function of the temperature (210〈T 〈350°K) for oriented films of isotactic polypropylene and polyethylene of high and low density.E andτ c change both upon heating and polymer orientation; this result indicates that sample properties are influenced by the microstructure of the amorphous phase where probes are localized.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01412710
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  • 47
    Digitale Medien
    Digitale Medien
    Photosynthesis and stomatal conductance of potato leaves—effects of leaf age, irradiance, and leaf water potential (1987)
    Springer
    Photosynthesis research 11 (1987), S. 253-264 
    Details
    ISSN: 1573-5079
    Schlagwort(e): Key words ; drought ; nitrogen content ; photosynthesis ; respiration ; stomata ; water relations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Potatoes (Solanum tuberosum L., cv. Bintje) were grown in a naturally lit glasshouse. Laboratory measurements on leaves at three insertion levels showed a decline with leaf age in photosynthetic capacity and in stomatal conductance at near saturating irradiance. Conductance declined somewhat more with age than photosynthesis, resulting in a smaller internal CO2 concentration in older relative to younger leaves. Leaves with different insertion number behaved similarly. The changes in photosynthesis rate and in nitrogen content with leaf age were closely correlated. When PAR exceeded circa 100 W m−2 the rate of photosynthesis and stomatal conductance changed proportionally as indicated by a constant internal CO2 concentration. The photosynthesis-irradiance data were fitted to an asymptotic exponential model. The parameters of the model are AMAX, the rate of photosynthesis at infinite irradiance, and EFF, the slope at low light levels. AMAX declined strongly with leaf age, as did EFF, but to a smaller extent. During drought stress photosynthetic capacity declined directly with decreasing water potential (range −0.6 to −1.1 MPa). Initially, stomatal conductance declined faster than photosynthetic capacity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00055065
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  • 48
    Digitale Medien
    Digitale Medien
    Evaluation of mineral metabolism and bone turnover in osteoporotic females treated with phosphorus and salmon calcitonin (1987)
    Springer
    Clinical rheumatology 6 (1987), S. 504-509 
    Details
    ISSN: 1434-9949
    Schlagwort(e): Senile Osteoporosis ; Phosphorus ; Salmonn Calcitonin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Twenty-five patients with radiological and clinical evidence of osteoporosis were studied. Nineteen patients received oral phosphorus at a dose of 1,000 mg/die for 10 days followed by salmon calcitonin (100 U MRC/die) for 20 days. Six patients received only oral calcium at a dose of 1,000 mg/die). In the first group, a significant increase in serum osteocalcin and parathyroid hormone, after administration of phosphorus and persisting after treatment with salmon calcitonin, was found. No variation in the controls was observed. In a later study, a significant increase in serum 1,25 dihydroxyvitamin D (1,25(OH)2D3), after receiving phosphorus and persisting after salmon calcitonin, was demonstrated. In accordance with the authors' results, phosphorus could be considered a useful activator of bone formation and this stimulus by parathyroid hormone was mediated. Finally, the positive effects of phosphorus on circulating 1,25(OH)2D3 must be considered for a good treatment protocol of osteoporosis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02330586
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  • 49
    Digitale Medien
    Digitale Medien
    Phosphorus nutrition of jarrah (Eucalyptus marginata) seedlings (1987)
    Springer
    Plant and soil 97 (1987), S. 369-379 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Bark ; Calcium phosphate ; Eucalyptus marginata ; Fertilizer ; Leaf ; Lignotuber ; Phosphorus ; Shoot growth ; Wood
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Effects of calcium phosphate supply on plant dry matter and phosphorus concentrations of parts of jarrah (Eucalyptus marginata) seedlings grown in a lateritic topsoil from the jarrah forest were examined in two glasshouse trials. Phosphorus deficiency depressed root and shoot dry weights and severely deficient leaves were smal and purple with prominent red major veins. Phosphorus deficiency severely reduced stem phosphorus levels (0.5% to 0.02%, experiment 1). Phosphorus concentrations were higher in bark than wood and the amount of phosphorus in the bark was sensitive to stem age and phosphate supply. Phosphorus adequate plants had bark phosphorus concentrations in the range 0.2–0.9% compared to 〈0.1% in deficient plants (experiment 2). Jarrah leaves accumulated dry matter up to 80 days after expansion and some leaves exported phosphorus during this period. Bark analysis may therefore be preferable to leaf analysis for detecting phosphorus deficiency in this species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02383227
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  • 50
    Digitale Medien
    Digitale Medien
    The effect of pretransplant inoculation with VA mycorrhizal fungi on the subsequent growth of leeks in the field (1987)
    Springer
    Plant and soil 97 (1987), S. 279-283 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Copper ; Dazomet ; Field experiment ; Leek ; Phosphorus ; Pretransplant inoculation ; VA mycorrhiza ; Zinc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Leek plants were preinoculated with a mixed inoculum ofGlomus caledonium, Glomus fasciculatum andGlomus sp., and transplanted to Dazomet disinfected and untreated field plots of moderate P deficiency. Successive harvests were made until 99 days after transplanting. Preinoculated leeks attained marketable weights 25 days earlier than uninoculated leeks from untreated soil and their final dry matter yields were 5.7 and 1.5 times as high as those of uninoculated leeks from disinfected and untreated soil, respectively. Phosphorus concentration in preinoculated leeks remained highest for at least 22 and 75 days after transplanting in untreated and disinfected soil, respectively. Preinoculation had a similar, although smaller, influence on Cu and Zn concentrations. Infection levels produced by introduced and indigenous VA endophytes in leeks reached plateaus of 90% and 40%, respectively, 47 days after transplanting. It is concluded that VAM is essential to leeks grown in moderately P deficient soils, and the potential for inoculating seedlings in commercial leek production is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02374951
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  • 51
    Digitale Medien
    Digitale Medien
    The effects of ferulic acid on the mineral nutrition of grain sorghum (1987)
    Springer
    Plant and soil 98 (1987), S. 99-109 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Allelopathy ; Ferulic acid ; Magnesium ; Mineral content ; Phosphorus ; PotassiumSorghum bicolor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Two week old sorghum seedlings (Sorghum bicolor L. Moench) were treated with ferulic acid added to the nutrient solution. Effects on tissue concentration of P, K, Mg, Ca, Fe, and Zn were evaluated after 3 and 6 days. Treatemnts of 0.25 mM ferulic acid approximated the growth inhibition threshold, and after 6 days 0.5 mM treated plants weighed less than controls. Both treatments reduced the P content of the roots and shoots at the 3- and 6-day harvests in three replicate experiments. Roots of treated plants at both harvests had a lower concentration of K and Mg. These reductions in P, K, and Mg were most extensive from the 0.5 mM ferulic acid regime. In some cases at both harvests, shoot K was lower and Mg was higher than control tissue. Ferulic acid effects at the 3-day harvest included an elevation of Ca and depression of Fe in shoots. Changes in nutrient content preceded measurable differences in plant weight. These data indicate that one mechanism of growth inhibition by this allelochemical may be an alteration of nutrient balance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02381731
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  • 52
    Digitale Medien
    Digitale Medien
    Nutrient variation in forest soil samples due to time of sampling and method of storage (1987)
    Springer
    Plant and soil 98 (1987), S. 363-375 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Ammonium ; Forest soil samples ; Nitrate ; pH ; Phosphorus ; Potassium ; Sample storage ; Seasonal variation ; Soil analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary This study was carried out in order to assess the importance of storage procedures and time of sampling for the results of routine chemical analyses of forest soils. Humus and mineral soil samples were collected at five-week intervals during two growing seasons from a sample plot in a coniferous forest in northern Sweden. The samples were either air-dried (+35°C) or frozen (−20°C). After a few months they were analysed for ‘easily available’ and ‘relatively available’ phosphorus (P-AL and P-HCl) and potassium (K-AL and K-HCl), ammonium, nitrate and pH. In some cases there was a significant difference between the two sample treatments. In humus, the concentrations of P-AL and NH4-N were 51% and 76% higher in samples which had been frozen than in those which had been air-dried while the concentrations of NO3-N were 75% higher. in air-dried than in frozen samples. In mineral soil samples, 21–64% higher concentrations of K-AL were found in frozen samples compared to air-dried and 80–427% higher concentrations of NO3-N in air-dried than in frozen samples. No distinct seasonal variations were found for any of the parameters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02378358
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  • 53
    Digitale Medien
    Digitale Medien
    Catalysis of hydrosilylation XIII.Partly presented at the 7th International Symposium on Organosilicon Chemistry, ‘Organosilicon Chemistry Directed to Practical Use’, Sept. 18-20, 1984, Kiryu, Japan. The lecture 202, Part XII, J. Organometal. Chem. is accepted for publication. Gas-phase hydrosilylation of acetylene by trichlorosilane on functionalised silica supported rhodium and ruthenium phosphine complexes (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 1 (1987), S. 267-273 
    Details
    ISSN: 0268-2605
    Schlagwort(e): Hydrosilylation ; Acetylene ; Trichlorosilane ; Silica ; Rhodium ; Ruthenium ; Catalysis ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Gas-phase hydrosilylation of acetylene by tri-chlorosilane catalyzed in a continuous flow apparatus by rhodium and ruthenium phosphine complexes immobilized on the silica via mercapto, phosphine, amine and nitrile ligands has been studied. GLC analysis of the reaction products showed vinyltrichlorosilane to be accompanied by products of double hydrosilylation of acetylene and the redistribution of trichlorosilane followed by the hydrosilylation and hydrogenative hydrosilylation of acetylene with dichlorosilane. A scheme for this complex competitive-consecutive reaction was proposed. The yield and selectivity of vinyltrichlorosilane can be much improved under special reaction conditions, e.g. rate flow of the particular substrates, temperature, given catalyst and others. Kinetic measurements carried out in the range of 115-140°C allowed us to evaluate the activation energy, Ea, for the vinyltrichlorosilane synthesis, which varied between 20.5 and 27.6 kJ mol-1 for the selected rhodium and ruthenium supported complexes.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aoc.590010309
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  • 54
    Digitale Medien
    Digitale Medien
    Directed Homogeneous Hydrogenation [New Synthetic Methods (65)] (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 26 (1987), S. 190-203 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Homogeneous hydrogenation ; Hydrogenation ; Synthetic methods ; Catalysis ; Stereoselectivity ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Stereochemical control is a major concern in the application of homogeneous catalysis to organic chemistry. In this context, the directed hydrogenation of olefins employing cationic rhodium or iridium catalysts has considerable potential, for very high selectivity can be attained under mild reaction conditions. The only requirement is a polar functional group in proximity to the double-bond which remains bound to the metal during the catalytic cycle and thereby controls the Stereochemical course of hydrogen delivery through the constraints of chelation. The substituent is most frequently a hydroxy group OH but can also be an ester, amide or carbamate group; other groups remain to be scrutinized. In cyclic compounds, directed hydrogenation can lead to face-selectivity, and the polar substituent may be in the β-, γ-, or δ-position to the double-bond. Acyclic stereoselection ensues with β- or γ-substituents in appropriate compounds, and the configuration of reduced product is predictable on the basis of simple rules. The application of optically active rhodium complexes leads to useful kinetic resolution procedures.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198701901
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  • 55
    Digitale Medien
    Digitale Medien
    Emission of Microparticles from Automotive Sources - X-ray Photoelectron Spectroscopy in Environmental Analysis (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 26 (1987), S. 309-319 
    Details
    ISSN: 0570-0833
    Schlagwort(e): EPR spectroscopy ; Automotive microparticle sources ; X-ray photoelectron spectroscopy ; Environmental chemistry ; Catalysis ; Photoelectron spectroscopy ; Microparticles ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In the last fifteen years the necessity for efficient environmental protection has become generally accepted. However, before practical measures can be taken, a comprehensive assessment of the present environmental situation should be made, taking into consideration the risks involved in as well as the positive effects of any planned environmental changes - whether natural or man made. This clearly calls for close cooperation between the various scientific disciplines. For example, the treatment of exhaust fumes from motor vehicles has been of primary importance in measures taken to restrict the recent damage caused to woodland areas. The introduction of 3-Way-Catalyst technology has been regarded as a viable countermeasure. The following report is intended to describe a method for examining some side effects of catalyst usage. Accordingly, the chemical composition of microparticles emitted from combustion motors through the use of catalysts will be examined and some possible changes in the environment caused by such particles will be briefly considered. As in the area of research into catalysts for industrial synthesis a knowledge of the surface structure of such particles, i.e. the boundary layer between emission product and environment, is necessary in the investigation into their effects. Consequently, a surface sensitive technique from solid state physics, X-ray photoelectron spectroscopy (XPS or ESCA) has found novel use in the area of environmental analysis. In the following report emphasis will be placed on the description of measurement techniques and the interpretation of the results obtained. After a critical consideration of the experimental methods, examples from two different series of measurements on diesel and Otto motors equipped with soot filters or 3-way-catalysts respectively, will be given. Hopefully, this report will also stimulate establishment of the use of EPS in environmental research techniques.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198703091
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  • 56
    Digitale Medien
    Digitale Medien
    Polyphosphorus Compounds - New Results and PerspectivesContributions to the Chemistry of Phosphorus, Part 178. - Part 177: [106].Dedicated to Professor Heinz Harnisch on the occasion of his 60th birthday (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 26 (1987), S. 419-441 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Polyphosphorus compounds ; Phosphorus ; Polyphosphanes ; Phosphanes ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In contrast to the numerous known and often technically important mono- and diphosphorus compounds with phosphorus in its maximum oxidation state, polyphosphorus compounds led only a shadowy existence up to about twenty years ago. One of the reasons for this was the properties of such compounds, which made their handling and structural characterization difficult. This problem was solved by the development of modern preparative techniques and, especially, by the further methodological development of nuclear magnetic resonance spectroscopy. Thus, a fascinating new branch of phosphorus chemistry has been opened up in recent years. The first comprehensive review on this subject was published five years ago. Since then, research on this “element-near” chemistry of phosphorus has produced further impressive advances with the result that a surprisingly large variety of compounds with skeletons consisting of chains or rings of phosphorus atoms is known today. However, the recent observation of the spontaneous formation of the “aromatic” pentaphosphacyclopentadienide ion, P5-, during the synthesis of phosphorus-richer polyphosphides from phosphorus-poorer compounds in solution and the discovery of the inversion of phosphorus in tetra- and pentacyclic organophosphanes demonstrate that this field is still capable of producing surprises.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198704191
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  • 57
    Digitale Medien
    Digitale Medien
    Metal catalysed Brooke rearrangement of 3-Halo-1-(trimethylsilyl) propan-2-one (Halo = Cl or Br) (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 1 (1987), S. 281-284 
    Details
    ISSN: 0268-2605
    Schlagwort(e): Catalysis ; Brooke rearrangment ; Iridium ; Palladium ; Platinum ; Complexes ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The complexes [IrH(CO)(PPh3)3], trans-[IrCI(CO)- (PPh3)2], [RhH(PPh3)4], [Pd(PPh3)4], [Pt(trans-stilbene)(PPh3)2] and [Pt(η3-CH2-COCH2)-(PPh3)2] catalyse the rearrangement of Me3SiCH2C(O)CH2Cl to CH2=C(OSiMe3)-CH2Cl.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aoc.590010311
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  • 58
    Digitale Medien
    Digitale Medien
    Vergleichende Messungen des Zeta-Potentials von Faserstoffen durch Elektroosmose und Strömungsstrom/Strömungspotential (1986)
    Springer
    Monatshefte für Chemie 117 (1986), S. 1133-1144 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Zetapotential ; Streaming potential ; Streaming current ; Electroosmosis ; Fibers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract An apparatus for the determination of zetapotential is described, which allows measurement of both streaming potential and streaming current as well as electroosmosis with one and the same fiber diaphragm with various electrodes (calomel, Ag/AgCl, palladium). Measurements with glass fibers, fibers of polyacrylonitrile and of polyester, and with cellulose pulp show that identical values for the electrokinetic parameters are obtained independent of voltage applied during electroosmosis resp. pressure difference during streaming measurements. This allows the conclusion that the zetapotential in dilute electrolyte solution is here an unequivocally determinable figure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00811326
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  • 59
    Digitale Medien
    Digitale Medien
    Silica anchored bis(trialkylphosphine) platinum oxalate. A photogenerated catalyst for olefin hydrosilation (1986)
    Springer
    Monatshefte für Chemie 117 (1986), S. 617-619 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Catalysis ; Photochemistry ; Supported platinum complex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Ultraviolettbetrahlung des siliziumverknüpften Komplexes Pt(C2O4)L 2 [L=(H3CO)3Si(CH2)2PEt 2] ergab eine [SiO2]-L 2Pt-Spezies, die die Hydrosilierung von Olefinen katalysiert oder unter Bildung eines Oberflächen-Dicarbonylkomplexes 2 CO addiert.
    Notizen: Abstract Ultraviolet irradiation of the silica attached complex Pt(C2O4)L 2, [L=(H3CO)3Si(CH2)2PEt 2], yields a [SiO2]-L 2Pt species that catalyzes olefin hydrosilation or adds 2 CO to yield a surface dicarbonyl complex.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00817899
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  • 60
    Digitale Medien
    Digitale Medien
    Study on the reactions of the dinitrogen complexestrans-[M(N2)2(Ph 2PCH2CH2PPh 2)2] (M=Mo or W) with ethyldiazoacetate: Formation of an Azo compound and of a phosphazene species (1986)
    Springer
    Monatshefte für Chemie 117 (1986), S. 429-435 
    Details
    ISSN: 1434-4475
    Schlagwort(e): Catalysis ; Dinitrogen complexes ; Ethyldiazoacetate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Komplexetrans-[Mo(N2)2(dppe)2] (dppe=Ph 2PCH2CH2PPh 2) reagieren mit NN=CHCOOEt in benzolischer Lösung zuPh-N=N-CH3 als organischem Hauptprodukt. Andererseits wird bei der Bestrahlung vontrans-[W(N2)2(dppe)2] inTHF-Lösung in der Gegenwart von Ethyldiazoacetat das PhosphazenPh 2P(N2CHCOOEt)(CH2CH2)P(N2CHCOOEt)Ph 2 gebildet; in feuchter Lösung erleidet die Phosphazen-Bindung eine teilweise Hydrolyse und die Phosphonium-Spezies [Ph 2P(NHNCHCOOEt)(CH2CH2)P(NHNCHCOOEt)Ph 2]2+ scheint gebildet zu werden.
    Notizen: Abstract Complextrans-[Mo(N2)2(dppe)2] (dppe=Ph 2PCH2CH2PPh 2) reacts with NN=CHCOOEt in benzene solution to afford benzene-azomethane,Ph-N=N-CH3, as the main organic product. However, the phosphazene speciesPh 2P(N2CHCOOEt)(CH2CH2)P(N2CHCOOEt)Ph 2 is formed by irradiating aTHF solution oftrans-[W(N2)2(dppe)2] in the presence of ethyldiazoacetate; in moist solution, the phosphazene bonds undergo a partial hydrolysis, and the phosphonium species [Ph 2P(NHNCHCOOEt)(CH2CH2)P(NHNCHCOOEt)Ph 2]2+ appears to be formed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00810890
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  • 61
    Digitale Medien
    Digitale Medien
    A second order monotone upwind scheme (1986)
    Springer
    Computing 36 (1986), S. 57-67 
    Details
    ISSN: 1436-5057
    Schlagwort(e): 65L ; Key words ; Convection-diffusion ; upwind finite differencing ; singular perturbation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Wir analysieren ein spezielles upwind-Differenzenschema für ein gewöhnliches, nichtlineares, singulär gestörtes Randwertproblem. Es wird insbesondere gezeigt, daß die Lösung des diskreten Problems eindeutig ist sowie monoton von der rechten Seite abhängt. Im globalen Gebiet ist die Methode von zweiter Ordnung.
    Notizen: Abstract We analyze a special finite difference scheme of upwind type for an ordinary singularly perturbed nonlinear boundary value problem. In particular we prove the uniqueness and monotone dependence upon the right hand sides of the discrete solutions and the second order accuracy in the global domain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02238192
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  • 62
    Digitale Medien
    Digitale Medien
    On the monotone convergence of Newton's method (1986)
    Springer
    Computing 36 (1986), S. 81-90 
    Details
    ISSN: 1436-5057
    Schlagwort(e): 65H10 ; Key words ; Systems of nonlinear equations ; Newton's method ; monotone convergence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Neue hinreichende Bedingungen für die monotone Konvergenz der Newton-Methode für die Lösung nichtlinearer Gleichung werden gegeben. Diese Bedingungen sind affin-invariant und allgemeiner als die Voraussetzungen des Satzes von Baluev.
    Notizen: Abstract New sufficient conditions for the monotone convergence of Newton's method for solving nonlinear systems of equations are given. These conditions are affine-invariant and less restrictive than the hypothesis of Baluev's theorem.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02238194
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  • 63
    Digitale Medien
    Digitale Medien
    Nutrient transport between ryegrass plants differeing in nutrient status (1986)
    Springer
    Oecologia 70 (1986), S. 128-131 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Lolium ; Nitrogen ; Nutrient transfer ; Phosphorus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary It is known that nitrogen and phosphorus can be transferred from one living plant to another, but it is not known whether the amounts transferred are large enough to influence the growth of the species in the field. Two Lolium perenne plants were grown per pot of unfertilized soil. During 25 weeks one plant (the ‘donor’) in each pot was fed nutrients through leaves; donors in control pots received only water. The ‘receiver’ plants which shared a pot with the nutrient-fed donors increased significantly, compared with the controls, in leaf number and concentration of phosphorus, though not in concentration of nitrogen, potassium, calcium or magnesium. The rate of phosphorus transfer agreed well with previous results using 32P. The results are compared with rates of phosphorus uptake in the field. It is concluded that nutrient transfer could have an influence on the balance between coexisting species in the field, but probably the influence will be small.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00377121
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  • 64
    Digitale Medien
    Digitale Medien
    Distribution of carbon, nitrogen and phosphorus in a moss community-soil system developed on a cold desert in Antarctica (1986)
    Springer
    Ecological research 1 (1986), S. 59-69 
    Details
    ISSN: 1440-1703
    Schlagwort(e): Antarctica ; Carbon ; Moss community ; Nitrogen ; Phosphorus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The distributions of carbon, nitrogen and phosphorus in a moss community-soil system developed on a naked region in Rundvågskollane (69050'S, 39009'E), East Antarctica, were investigated in order to analyze the flow of matter in an Antarctic terrestrial ecosystem. 1) The moss community was formed from many moss blocks of different sizes and was composed ofBryum pseudotriquetrum (Hedw.) Gaertn., Meyer et Scherb.,Ceratodon purpureus (Hedw.) Brid. andGrimmia lawiana J. H. Willis. The surface of the community was covered with cyanobacteria. 2) It was estimated that nitrogen fixed by cyanobacteria flowed from these organisms to the moss and that little nitrogen was transported within the moss body. 3) A large amount of phosphorus existed in the soil. The moss community had a high phosphorus content although the amount itself was relatively little due to the small phytomass. 4) It seems that absorption of phosphorus from soil is difficult for moss, because of the paucity of water necessary for the movement of phosphorus and the suppressed growth of moss due to the arid conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02361205
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  • 65
    Digitale Medien
    Digitale Medien
    The influence of drainage and soil phosphorus on the vegetation of Douala-Edea Forest Reserve, Cameroun (1986)
    Springer
    Plant ecology 65 (1986), S. 149-162 
    Details
    ISSN: 1573-5052
    Schlagwort(e): Africa ; Cameroun ; Douala-Edea ; Drainage ; Gradient ; Phosphorus ; Rain-forest
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract All living trees (≥30 cm gbh) were enumerated in 104 80×80 m plots arranged along four transects in the Douala-Edea Forest Reserve Cameroun, a system of low-lying ancient coastal sand dunes interspersed by numerous streams and swamps. The extent of permanent and seasonal swamps was recorded for each plot. Two hundred thirty taxa were recognized of which 63% were identified to species. Mean tree density was 376 ha−1, basal area 31.0 m2 ha−1 and number of species per plot 39. The Olacaceae were the most abundant family in terms of basal area, but the Euphorbiaceae the most frequently represented. The most abundant species wasCoula edulis (Olacaceae). Twenty-two plots had most of their area permanently or seasonally swamped. Percentage sand, silt and clay ranged between 32–100, 0–64, 0–21% respectively. The ranges for other variables recorded were: pH (2.7–5.4), organic carbon (1.5–12.4%), available phosphorus (7–90 ppm) and potassium (28–188 ppm), and nitrogen (ammonium 4–40 ppm, nitrate 1–12 ppm). Classification of the plots on the basis of six soil variables provided three large distinct groups: swamp plots and non-swamp plots, the latter divided into plots of low and high available soil phosphorus. Swamp plots were distinguished by high abundances ofProtomegabaria stapfiana andLibrevillea klainei, though correspondence ordination of plots in these groups showedP. stapfiana associated with more clayey soils andLibrevillea klainei (andGluema ivorensis) on the very sandy soils. Direct gradient analysis highlighted several species associated with these lower phosphorus soils. Available soil phosphorus is not as low at Douala-Edea as in parts of Korup, and the association of these Douala-Edea soils with the Caesalpinioideae is correspondingly weaker.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00044815
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  • 66
    Digitale Medien
    Digitale Medien
    The influence of topography and soil phosphorus on the vegetation of Korup Forest Reserve, Cameroun (1986)
    Springer
    Plant ecology 65 (1986), S. 131-148 
    Details
    ISSN: 1573-5052
    Schlagwort(e): Africa ; Cameroun ; Gradient ; Korup ; Phosphorus ; Rain-forest ; Topography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract All living trees (≥30 cm gbh) were enumerated in 135 80×80 m plots, each subdivided into four 40×40 m subplots, and arranged along four 5 km transect lines in the Korup Forest Reserve, Cameroun. For each plot altitude, slope and the extent of permanent and seasonal swamps were recorded. Four hundred and eleven taxa were recognized of which 66% were identified to species. Mean tree density was 471 ha−1, basal area 27.6 m2 ha−1 and number of species per plot 75. The subfamily Caesalpinioideae (Leguminosae) was the most abundant family/subfamily in terms of basal area, but the Scytopetalaceae the most frequently represented, mainly on account ofOubanguia alata. Ten plots had at least three quarters of their area permanently swamped, and three, to a similar extent, were seasonally swamped. The ranges in sand, silt and clay content were 60–91, 0–24 and 4–20% respectively. The pH value, organic carbon content and nitrate-nitrogen concentration ranged between 4.0–5.8, 1.3–5.7% and 0–35 ppm respectively. The largest soil variations were in available phosphorus, range 2–29 ppm, and potassium, 38–375 ppm. Correspondence analysis ordination of all plots showed a major indirect floristic gradient correlated with increasing altitude, slope and soil phosphorus and potassium. Removal of the topographic effect by separate re-ordinations of four groups of plots at low, middle (2) and high altitude/slopes highlighted a strong correlation of the main floristic gradients of the middle altitude/slope groups with the concentration of available soil phosphorus. Direct gradient analysis using all plots with respect to available soil phosphorus concentration confirmed the indirect analyses. Individual species response to phosphorus were also shown by direct comparisons in the vegetation on plots of high and low available soil phosphorus concentration. Low available phosphorus soils (≤5 ppm) are strongly associated with species of the subfamily Caesalpinioideae, especially of the tribes Amherstieae and Detarieae. It is suggested that this result is probably due to the ability of these particular legume tribes to form associations with ectotrophic mycorrhizae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00044814
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  • 67
    Digitale Medien
    Digitale Medien
    Long-term effects of cutting tap roots ofPinus caribaea growing on infertile savanna soils (1986)
    Springer
    Plant and soil 93 (1986), S. 137-140 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Calcium ; Magnesium ; Phosphorus ; Pinus caribaea ; Potassium ; Savanna ; Tap root
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The content of elements in needles ofPinus caribaea trees growing upon infertile savanna soils was analysed at 3 and 5 years after the tap roots of a subset of trees had been severed. No significant differences were found between the content of elements in treated and control trees, nor were significant differences found in increments of diameter of the trees over 5 years. It is concluded that this organ plays no significant nutritional role in the trees on these soils, and that tree growth can be achieved exclusively from atmospheric nutrient accessions and exchangeable nutrient reserves in the topsoil.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02377154
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  • 68
    Digitale Medien
    Digitale Medien
    The effects of soil temperature on the response of lettuce seedlings to starter fertilizer (1986)
    Springer
    Plant and soil 93 (1986), S. 183-193 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Ammonium phosphate ; Lactuca sativa L. ; Phosphorus ; Placement ; Potassium phosphate ; Root-shoot ratio ; Soil temperature ; Starter fertilizer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A pot experiment is described which investigated the effects of placing starter fertilizer, 1 cm beneath the seeds, on growth and nutrient uptake in lettuce seedlings at two soil temperatures (10°C and 20°C). At both temperatures the presence of starter fertilizer increased nutrient concentrations within the plants. At 20°C there was no growth response to the starter treatments. However, at 10°C there was a large response to the application of starter fertilizer. The best treatment was a combination of NH4H2PO4 and KH2PO4 which increased plant dry weight by 64% at 19 days from sowing. Nutrient deficiency caused a significant increase in the root length/shoot weight ratio of the control plants at 10°C. The responses to the starter were shown to be determined by the balance between the demand for nutrients from the shoots and the supplying power of the roots.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02374220
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  • 69
    Digitale Medien
    Digitale Medien
    Fate of applied nutrients in a long-term superphosphate trial inPinus radiata (1986)
    Springer
    Plant and soil 93 (1986), S. 373-382 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Calcium ; Fertilizer ; Magnesium ; Nitrogen ; Nutrient content ; Phosphorus ; Pinus radiata ; Potassium ; Superphosphate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Nutrient contents of aPinus radiata stand, that is, aboveground tree, understorey, forest floor and soil to 200 mm depth, were estimated in a replicated fertilizer trial, treated 30 years previously. The fertilizer treatments were 0, 25, 50, 75 and 100 kg P/ha as broadcast superphosphate. Highly significant growth responses had been obtained to the applied P. Estimation of the P content of the stand showed that 129%, 89%, 72% and 67% of the applied P was found in the 25, 50, 75 and 100 kg P/ha treatments respectively. The larger losses of P at the higher application rates would explain the lack of increased response with the highest application rate, however, it also shows that significant quantities of P are still present after a period of 30 years, giving a basis for growth responses in the subsequent rotations. Elevated quantities of N, Ca, Mg and K were found in the treatments compared with the control and these could not be explained on the basis of atmospheric inputs. For the cations, uptake from deeper in the soil profile could explain most of the effect but not for the higher amounts of N which, in the case of the highest superphosphate treatment, amounted to an accumulation of 27 kg N/ha/yr. These nutrient changes together with increased soil organic matter contents are considered to have provided a long term increase to the site productivity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02374288
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  • 70
    Digitale Medien
    Digitale Medien
    Development of two endomycorrhizal symbioses on soybean and comparison with phosphorus fertilization (1986)
    Springer
    Plant and soil 95 (1986), S. 361-377 
    Details
    ISSN: 1573-5036
    Schlagwort(e): glomus fasciculatum ; Glomus mosseae ; Glycine max ; Phosphorus ; Specific P Uptake Rate (SPUR) ; Vesicular-arbuscular mycorrhiza (VAM)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Soybean (Glycine max L. Merr. cv. Amsoy 71) plants were grown in a greenhouse in a soil very low in plant-available P, and plants were harvested 5 times over a 21-week growth period. Soybeans were inoculated with one of two species of VAM fungi or received daily one of three nutrient solutions of different P concentrations (0.0, 0.2, or 1.0mMP). Until week 9, the dry weights, leaf areas and developmental stage of soybeans inoculated withG. fasciculatum orG. mosseae were similar to the 1.0 or 0.2mMP-treated plants, respectively. Phosphorus concentrations were significantly lower in VAM plants at weeks 6 and 9 as compared to non-VAM soybeans given 1.0mMP, suggesting P input in VAM plants was immediately used for new growth. Total P input for VAM plants was linear over 21 weeks, and the average rate of P uptake for these plants was 0.19mg P d−1. Estimated specific P uptake rates (SPUR) for the mycorrhizae (VAM roots) were twice that of the control (0.0mMP) roots. The calculated SPURs forG. fasciculatum andG. mosseae hyphae were 95 and 120μg P g−1 VAM d−1 respectively, a 4 to 5 fold increase over non-inoculated roots, indicating more attention must be paid to P assimilation by VAM fungi in P-fixing substrates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02374617
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  • 71
    Digitale Medien
    Digitale Medien
    Effects of temperature and prior flooding on intensity and sorption of phosphorus in soil (1986)
    Springer
    Plant and soil 95 (1986), S. 173-181 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Apparent heat of sorption ; Bonding energy ; Flooded-drain ; Phosphorus ; Phosphate ; Sorption ; Temperature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The effects of temperature and prior flooding of soil on P sorption were examined in 2 soils having a rice-based cropping system and showing an induced P deficiency problem in flooded rice-uplant crop rotations. The P sorption capacity of soil increased with increasing temperature as well as with prior flooding, the effects of the latter were, howerver, dominant. The bonding energy of sorption, calculated from the Langmuir isotherm, also increased with both temperature and prior flooding of soils, indicate that the effects of chemical changes associated with alternative anoxic and oxidized soil conditions are more significant in the P reversion process. The apparent heat of sorption reaction, calculated with the Freundlich isotherm and Van't Hoff's equation also increased due to prior flooding of soil.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02375069
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  • 72
    Digitale Medien
    Digitale Medien
    Sorption and bioavailability of phosphorus during the drainage period of flooded-drained soils (1986)
    Springer
    Plant and soil 92 (1986), S. 265-278 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Bioavailability ; Bonding energy ; Flooded-drained ; Phosphorus ; Phosphorus sorption ; P uptake
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Changes in P sorption and bioavailability were studied with 4 soils previously flooded and drained as occurs in rice-based cropping systems. Phosphorus sorption was measured at 15 and 119 days after drainage and the bioavailability of added and native soil-P was determined at 9, 16, 30, 45, 70 and 135 days in both flooded-drained and unflooded soils. The P sorptivity and bonding energy of sorption increased under flooded-drained soil conditions. At 119 days after drainage the P sorptivity and bonding energy of sorption decreased as compared to 15 days after drainage. The P sorptivity of the flooded-drained soils, however, did not reach the same levels as existed in the soils prior to flooding. The bioavailability of P during the drainage period remained low and did not measurably change up to 70 days after drainage. At 135 days after drainage the bioavailability of P increased significantly, but did not reach the level found in the corresponding unflooded soils.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02372640
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  • 73
    Digitale Medien
    Digitale Medien
    Phosphorus deficiency induced by nitrogen input in Douglas fir in the Netherlands (1986)
    Springer
    Plant and soil 95 (1986), S. 191-200 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Atmospheric input ; Douglas fir Fertilization ; Foliar analysis ; Forest nutrition ; N/P ratio ; Nitrogen ; Nutrient status ; Phosphorus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A re-examination of earlier NPK fertilization experiments in Douglas fir stands on sandy soils shows the effects of high nitrogen input by air pollution during the last 10–15 years on plant nutrition at these sites. In 1960, experimental plots showed a positive growth reaction to nitrogen, phosphorus, and potassium fertilization. All suffered from severe phosphorus deficiency in 1984, low phosphorus in the needles was invariably accompanied by a high nitrogen content, with all N/P ratios between 20 and 30. The same conclusion emerges from an independent investigation of nutrient status of a selection of Douglas fir stands. Hence, if stand productivity and a balanced nutrient status of the trees is to be maintained, the increase in atmospheric input of nitrogen calls for supplementary fertilization. Given the current N/P ratios in the needles, a positive growth response to phosphorus fertilization is to be expected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02375071
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  • 74
    Digitale Medien
    Digitale Medien
    Growth response ofTheobroma cacao L. seeldings to inoculation with vesicular-arbuscular mycorrhizal fungi (1986)
    Springer
    Plant and soil 96 (1986), S. 279-285 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Mycorrhiza ; Phosphorus ; Plant growth ; Theobroma cacao
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The effects of vesicular-arbuscular mycorrhiza (VAM) on the growth and phosphorus uptake of cocoa seedlings (Theobroma cacao L.) grown for 100 days in polythene bags, were studied at five levels of phosphorus fertilization in both steamed and unsterile Bungor Series soil (a fine clayey, kaolinitic isohyperthermic Typic Paleudult). The cocoa seedlings responded well to phosphorus fertilization and mycorrhizal treatments. Plants inoculated with VAM fungi (Gigaspora spp.) gave the most vigorous growth and higher phosphorus in the leaf tissues in unsterile soil compared to plants grown in steamed soil. However, the mycorrhizal effect was significantly more pronounced (P〈0.01) in plants grown in steamed than in unsterile soil. High levels of phosphorus application depressed mycorrhizal development. Phosphorus fertilizer applied at the rates of 250 and 500 ug g−1 soil gave maximum root colonization and spore counts in both soil types used.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02374771
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  • 75
    Digitale Medien
    Digitale Medien
    Nitrate and ammonium absorption by plants growing at a sufficient or insufficient level of phosphorus in nutrient solutions (1986)
    Springer
    Plant and soil 91 (1986), S. 313-318 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Ammonium uptake ; Barley ; Brassica napus L. ; Buckwheat ; Cation-anion balance ; Fagopyrum esculentum Moench ; Hordeum vulgare L. ; Nitrate uptake ; Phosphorus ; Rape
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Absorption of nitrate and ammonium was studied in water culture experiments with 4 to 6 weeks old plants of barley (Hordeum vulgare L.), buckwheat (Fagopyrum esculentum L. Moench) and rape (Brassica napus L.). The plants were grown in a complete nutrient solution with nitrate (5.7±0.2 mM) or nitrate (5.6±0.2 mM) + ammonium (0.04±0.02 mM). The pH of the nutrient solution was kept at 5.0 using a pH-stat. It was found that phosphorus deficiency reduced the rate of nitrate uptake by 58±3% when nitrate was the sole N source and by 83±1% when both nitrate and ammonium were present. The reduction occurred even before growth was significantly impeded by P deficiency. The inhibition of the uptake of ammonium was less,i.e. ammonium constituted 10±1% of the total N uptake in the P sufficient plants and 30±5% in the P deficient plants. The reduction of nitrate absorption greatly decreased the difference between the uptake of anions and cations. It is suggested that P deficiency reduced the assimilation of NO 3 − into the proteins, which might cause a negative feedback on NO 3 − influx and/or stimulate NO 3 − efflux.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02198114
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  • 76
    Digitale Medien
    Digitale Medien
    A Receptor-Mediated Pathway for Cholesterol Homeostasis (Nobel Lecture)Copyright © The Nobel Foundation 1986. - We thank the Nobel Foundation, Stockholm, for permission to print this article. (1986)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 25 (1986), S. 583-602 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Cholesterol homeostasis ; Receptors ; Catalysis ; Nobel lecture ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198605833
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  • 77
    Digitale Medien
    Digitale Medien
    The Palladium-Catalyzed Cross-Coupling Reactions of Organotin Reagents with Organic Electrophiles [New Synthetic Methods (58)] (1986)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 25 (1986), S. 508-524 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Cross-coupling ; Organotin compounds ; Electrophilicity ; Palladium ; Catalysis ; C-C coupling ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The cross-coupling of organotin reagents with a variety of organic electrophiles, catalyzed by palladium, provides a novel method for generating a carbon-carbon bond. Because this mild, versatile reaction is tolerant of a wide variety of functional groups on either coupling partner, is stereospecific and regioselective, and gives high yields of product, it is ideal for use in the synthesis of elaborate organic molecules. When the coupling reaction is carried out in the presence of carbon monoxide, instead of a direct coupling, carbon monoxide insertion takes place, stitching the two coupling partners together and generating a ketone.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198605081
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  • 78
    Digitale Medien
    Digitale Medien
    Hydroxide Ion Initiated Reactions Under Phase Transfer Catalysis Conditions: Mechanism and Implications. New Synthetic Methods (62) (1986)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 25 (1986), S. 960-970 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Phase-transfer catalysis ; Catalysis ; Synthetic methods ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The development of Phase Transfer Catalysis (PTC) represents a major step forward in the employment of many organic reactions and renders them very convenient and useful processes. These reactions involve the application of nucleophiles in general, anions and bases in particular, in reactions carried out in a water-organic solvent system. They can be performed both in the laboratory and on an industrial scale. The ease of application of PTC processes is the main reason for their increasing utilization in industry. An outstanding achievement of this technique is the employment of aqueous bases in reactions which traditionally would otherwise require a strong base in a nonaqueous medium. The classical procedures that require severe anhydrous conditions, expensive solvents and dangerous bases such as metal hydrides and organometallic reagents are now replaced by aqueous solutions of, e.g., sodium or potassium hydroxides (PTC/OH processes). In contrast to the extensive synthetic applications of PTC/OH systems, the detailed mechanisms of these processes have been the subject of a great deal of controversy and various mechanisms have been suggested. However, it would seem that our knowledge concerning the mechanistic aspects of such reactions has now reached the stage where it can be used to advantage in synthesis planning. A better understanding of the various factors which influence the reaction would undoubtedly help to optimize PTC/OH processes such as to enable higher yields in shorter reaction times at lower temperatures. The importance of, inter alia, the catalyst will be pointed out and it is highly recommended that such catalysts be always available in the laboratory, for the range of organic reactions that they can efficiently, conveniently and safely catalyze is vast indeed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198609601
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  • 79
    Digitale Medien
    Digitale Medien
    Study of the effect of N-protonation and N-methylation on the 1H and 13C chemical shifts of the six-membered ring in benzazoles and 2-substituted N,N-dimethylamino derivatives (1986)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 415-420 
    Details
    ISSN: 0749-1581
    Schlagwort(e): Heterocycles ; Benzazoles ; Amino Derivatives ; Cation formation ; 1H and 13C ; NMR ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The 1H and 13C NMR spectral data of benzimidazole, benzoxazole, benzothiazole and N-methylbenzimida-zole and of their 2-N,N-dimethylamino derivatives are reported. The spectra were recorded in acetone-water solution. The chemical shifts of these molecules are compared with those of the corresponding cations obtained by N-protonation and N-methylation of the neutral molecules. The carbon atoms C-4, C-5, C-6 and C-4a show a qualitatively identical behaviour, moving to higher field when the cations are formed from the benzazoles examined, but a different behaviour is found for C-2, C-7 and C-7a, which depends on the heterocyclic ring, on the presence of the substituent in position 2 and on the type of cation formed (N-protonation and N-methylation cause different effects). The conversion of benzazoles into the corresponding cations causes all 1H chemical shifts to move to lower field.
    Zusätzliches Material: 8 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrc.1260240505
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  • 80
    Digitale Medien
    Digitale Medien
    [3+2] Cycloaddition Approaches to Five-Membered Rings via Trimethylenemethane and Its Equivalents [New Synthetic Methods (55)] (1986)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 25 (1986), S. 1-20 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Cycloaddition ; Trimethylenemethane ; Synthetic methods ; Cyclopentanes ; Heterocycles ; Natural products ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The power of cycloadditions for ring formation derives from the potential for chemo-, regio-, diastereo-, and enantioselectivity. Trimethylenemethane (TMM) and its equivalents offer the possibility of extending such benefits to the synthesis of five-membered rings. Three types of conjunctive reagents appear to be promising candidates: (1) selected 4-alky-lidene-4,5-dihydro-3H-pyrazoles, (2) 2-[(trimethylsilyl)methyl]allyl esters and halides, and (3) alkylidenecyclopropanes. Thermal reactions, especially intramolecular ones, effect the cycloaddition of the pyrazoles to olefins-especially electron-poor olefins. The latter two precursors require a catalyst, notably a palladium complex, to unlock the synthetic potential. With the 2-[(trimethylsilyl)methyl]allyl esters, a general chemo-, regio-, and diastereoselective cycloaddition with typical Diels-Alder dienophiles forms methylenecyclopentanes in both inter- and intramolecular fashion. A tin analogue allows extension of this cycloaddition to aldehydes, and, in a related sequence, to ketones and imines to form 3-methylenete-trahydrofurans and 3-methylenepyrrolidines with excellent diastereoselectivity. The 2-[(tri-methylsilyl)methyl]allyl esters also serve to effect net methylenecyclopentane annulation to cyclic enols. Such adducts can further undergo three-carbon intercalation or combined ring contraction-spiroannulation simply by the use of either a nucleophilic or electrophilic trigger. Alkylidenecyclopropanes undergo cycloadditions to both electron-rich and electron-poor olefins when stimulated by metal catalysts, especially palladium. A complementary regiochemistry to the approach based upon silicon conjunctive reagents is observed. The availability of these cycloadditions provides new strategies for the synthesis of natural products.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198600013
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  • 81
    Digitale Medien
    Digitale Medien
    Un modèle non local en physique des plasmas: résolution par une méthode de degré topologique (1985)
    Springer
    Acta applicandae mathematicae 4 (1985), S. 1-14 
    Details
    ISSN: 1572-9036
    Schlagwort(e): 47H17 ; 82A45 ; Key words ; Plasma physics ; free boundary problem
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract Under a few assumptions on the functiong, we prove the existence of the following-free boundary problem: Findu inH 2(Ω) satisfying: $$\begin{gathered} \Delta u \in g(x, u(x)), [\delta (u)(x), \bar \delta (u)(x)] in \{ u〈 0\} \hfill \\ \Delta u = 0 in \{ u \geqslant 0\} \hfill \\ u = constant (but unknown) on the boundary \partial \Omega of \Omega \hfill \\ \int_{\partial \Omega } {\frac{{\partial u}}{{\partial n}}d\sigma = I 〉 0} (given number) \hfill \\ \end{gathered} $$ where $$\delta (u)(x) = meas \{ y \in \Omega , u(x)〈 u(y)〈 0\} ,\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{\delta } (u)(x) = meas\{ y \in \Omega , u(x) \leqslant u(y) \leqslant 0\} $$ . This is a model of the Grad-Mercier-type describing the equilibrium of a confined plasma in a Tokamak machine.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02293489
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  • 82
    Digitale Medien
    Digitale Medien
    The aluminum-induced increase in blood-brain barrier permeability to delta-sleep-inducing peptide occurs throughout the brain and is independent of phosphorus and acetylcholinesterase levels (1985)
    Springer
    Psychopharmacology 86 (1985), S. 84-89 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Blood-brain barrier ; Aluminum ; Dementia ; Peptides ; Phosphorus ; Acetylcholinesterase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effect of aluminum on levels of inorganic phosphorus and acetylcholinesterase in blood and brain and on permeability of the blood-brain barrier (BBB) in different regions of the brain to the neuropeptide deltasleep-inducing peptide (DSIP) was studied in adult rats. Aluminum (100 mg/kg) significantly increased the permeability of the BBB to intracarotid 125I-N-Tyr-DSIP so that levels of radioactivity in whole brain were 45% higher than in control animals. The pattern of regional distribution of radioactivity in the brain was, however, unaffected, demonstrating that the affect of aluminum occurs throughout the BBB. Aluminum also significantly decreased inorganic phosphorus levels in the serum by 19%, but this effect did not correlate with BBB permeability to DSIP. Aluminum did not decrease brain levels of phosphorus despite the drop in blood levels of phosphorus nor affect brain or blood levels of acetylcholinesterase. Experiments with radioactive 32P reinforced the finding that blood but not brain levels of phosphorus are reliably affected by aluminum. The lack of correlation between changes in BBB permeability and decreased levels of inorganic phosphorus in the blood suggests that the effect of aluminum may not be mediated by its effects on phosphorus metabolism. Also, the change in BBB permeability after administration of aluminum does not appear to depend on changes in brain cholinergic activity but does occur throughout the brain.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00431689
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  • 83
    Digitale Medien
    Digitale Medien
    Nutrient fluxes in a eutrophic coastal Louisiana freshwater lake (1985)
    Springer
    Environmental management 9 (1985), S. 243-251 
    Details
    ISSN: 1432-1009
    Schlagwort(e): Water quality ; Nitrogen ; Phosphorus ; Sedimentation ; 137Cs dating ; Freshwater lake ; Nutrient sinks ; Eutrophication
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract Nitrogen and phosphorus cycling in a eutrophic Louisiana freshwater lake system (Lac des Allemands) was studied. Nutrients from runoff entering the lake, as well as sediment-interstitial and lake water nitrogen and phosphorus fractions, were measured seasonally. Sedimentation rates in the lake were determined using137Cs dating. Phosphorus levels in the lake were found to be largely dependent on concentrations in the incoming bayou water from upland drainage. Lake water concentrations appear to respond to fluctuations in incoming waters. Laboratory equilibrium studies showed bottom sediments in the lake are a major sink for the incoming dissolved orthophosphate phosphorus. Total nitrogen concentrations in the lake water generally exceeded incoming runoff concentrations, suggesting fixation by the large blue-green algae population in the lake as being the major source of nitrogen to the system. Sedimentation ranged from 0.44 cm/year to 0.81 cm/year, depending on the proximity to the inlet bayous. Even though the lake is eutrophic the sediment served as a buffer by removing large amounts of carbon, nitrogen, and phosphorus through sedimentation processes. Carbon, nitrogen, and phosphorus were accumulating in the sediment at rates of 60, 7.1, and 1.1 g/m2/year, respectively. The water quality of the lake is likely to continue to decline unless measures are taken to reduce municipal, industrial, and agricultural inputs of phosphorus into the lake.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01867080
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  • 84
    Digitale Medien
    Digitale Medien
    Effects of synthetic and microbially produced chelates on the diffusion of iron and phosphorus to a simulated root in soil (1985)
    Springer
    Biology and fertility of soils 1 (1985), S. 45-52 
    Details
    ISSN: 1432-0789
    Schlagwort(e): Iron ; Phosphorus ; Siderophore ; Hydroxamate ; Chelates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Hydroxamate siderophores (HS) are microbially produced, ferric-specific chelates, known to occur in soil, and to be capable of providing iron to higher plants. This study examined the potential for HS to influence the diffusion of both iron and phosphorus to plant roots in soil. The HS desferrioxamine-B (DFOB) and desferriferrichrome (ferrichrome) were compared with the synthetic chelates ethylenediamine [di(o-hydroxyphenylacetic)acid] (EDDHA) and ethylenediamine-tetraacetic acid (EDTA), and citrate, oxalate, and distilled water in their ability to increase diffusion of iron using a simulated root technique. Chelate solutions were pumped through porous fiber bundles imbedded in soil previously labeled with55Fe. In a sandy loam of pH 7.5,55Fe diffusion caused by 10−4 M DFOB was twice that of water, but similar to that caused by 10−4 M EDDHA. However, 10−3 M EDDHA resulted in greater diffusion than 10-3 M DFOB. The diffusions resulting from equimolar quantities of citrate, oxalate, and EDTA were similar to that with distilled water. In a clay soil of pH 5.2 previously labeled with55Fe and32 P, the response in55Fe diffusion to chelate treatments was: 10−4 M EDDHA 〉 10−4 M ferrichrome 〉 10−3 M DFOB 〉 10−4 M DFOB 〉 water. Both ferrichrome and EDDHA caused2 P diffusion to increase substantially over that of distilled water. These results suggest that hydroxamate siderophores present in the rhizosphere could effectively increase the level of soluble iron for root uptake and possibly increase phosphorus uptake by solubilization of phosphorus from iron phosphates at acid pH.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00710970
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  • 85
    Digitale Medien
    Digitale Medien
    Comparative effects of four mycorrhizal fungi on loblolly pine seedlings growing in a greenhouse in a Piedmont soil (1985)
    Springer
    Plant and soil 83 (1985), S. 215-221 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Cecil soil type ; Phosphorus ; Pinus taeda ; Scleroderma aurantium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A greenhouse study was conducted to evaluate the effect of ectomycorrhizae on loblolly pine (Pinus taeda L.) growing in a Piedmont soil. Pine seedlings were inoculated with one of four species of fungi (Scleroderma aurantium, Pisolithus tinctorius, Thelophora terrestris, andRhizopogon roseolus). The seedlings were grown in pots containing a Cecil sandy clay loam amended to create a gradient of extractable P ranging from 5.9 to 52.5 μg/g. After ten months, all colonized seedlings were significantly larger than control seedlings. However, of the four fungi,Scleroderma aurantium mediated a far superior shoot growth response to increasing levels of soil P; the seedlings were significantly larger than those colonized by any other fungus and also had the largest root systems and greatest degree of mycorrhizal colonization.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02184293
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  • 86
    Digitale Medien
    Digitale Medien
    Influence of nitrogen and phosphorus fertilizers on ammonia-assimilating enzymes of Azolla (1985)
    Springer
    Plant and soil 88 (1985), S. 271-273 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Ammonia assimilating enzymes ; Anabaena azollae ; Azolla ; Nitrogen ; Phosphorus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary A field experiment was conducted and studied the effect of nitrogen and phosphorus on ammonia assimilating enzymes of Azolla. Nitrogen and phosphorus at 30 and 60 kg/ha respectively were tested andAzolla pinnata was inoculated at 200 g/m2. The Azolla samples were drawn on 24th hr, 7th day and 14th day and the ammonia assimilating enzymes glutamine synthetase (GS), glutamate synthase (GOGAT) and glutamine dehydrogenase (GDH) were estimated. Nitrogen and phosphorus have markedly suppressed the GDH activity but fertilizer nitrogen has no significant influence in inhibiting the enzyme activity of GOGAT and GS. In general phosphorus application also has stimulated the GS activity significantly during the first sampling period of 24th hour.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02182453
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  • 87
    Digitale Medien
    Digitale Medien
    Fertilization management of crops irrigated with saline water (1985)
    Springer
    Plant and soil 89 (1985), S. 285-299 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Calcium ; Chloride ; Ion antagonism ; Magnesium ; Nitrate ; Nitrogen ; Nutrition disorders ; Phosphorus ; Salinity-fertility relationship ; Sodium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Available data concerning nutrition and fertilization effects on crops irrigated with saline water are presented and discussed. Published data on the salinity-fertility relationship are, at least to some extent, contradictory; both positive and negative effects as well as no effect of fertilization on salinity tolerance have been recorded. However, a great deal of the experimental work supports the view that standard fertilization recommendations for non-saline conditions are also suitable for saline conditions. In addition, available data indicate that the apparent salt tolerance of agricultural crops varies with soil fertility level. Consequently, crops showing exceptionally high apparent salt tolerance at a low fertility level become more sensitive when adequately fertilized, although the absolute yield may be greatly increased. On the other hand, some data seem to show a real increase in salinity tolerance under improved fertility conditions. Important information concerning the responses of plants to salinity under various fertility levels was obtained by tissue analysis. It should be kept in mind that this information may be influenced also by the plant species and by environmental conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02182248
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  • 88
    Digitale Medien
    Digitale Medien
    Extraction of DNA from milligram amounts of fresh, herbarium and mummified plant tissues (1985)
    Springer
    Plant molecular biology 5 (1985), S. 69-76 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Key words ; cetyltrimethylammonium bromide ; CTAB
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have developed a DNA extraction procedure for milligram amounts of plant tissue. Yields ranged from 0.3–200 nanograms of DNA per milligram of tissue. The factors affecting yield are discussed. Fresh tissue, as well as herbarium specimens (22–118 years old) and mummified seeds and embryos (500 to greater than 44 600 years old) were used. All tissues attempted (57 types from 29 species) yielded measurable amounts of DNA. In no case tested was inhibition observed for restriction enzymes BamHI or EcoRI.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00020088
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  • 89
    Digitale Medien
    Digitale Medien
    Influence of washing on elemental analysis of leaves of fieldgrown crop plants (1985)
    Springer
    Plant and soil 88 (1985), S. 93-100 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Aluminum ; Calcium ; Copper ; Glycine max ; Iron ; Magnesium ; Manganese ; Nitrogen ; Phosphorus ; Potassium ; Sorghum bicolor ; Triticum aestivum ; Zea Mays ; Zinc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Information is limited on soil contamination of leaves from field-grown row crops, especially with respect to aluminum (Al) analyses. The objective of this study was to determine the influence of washing leaf samples with either deionized water or detergent solution on elemental analyses for several agronomic crop plants. The crop plants sampled were corn (Zea mays L.), soybean (Glycine max L. Merr.), grain sorghum (Sorghum bicolor L. Moench), and wheat (Triticum aestivum L.). The crops were grown on a range of soil types, soil pH values, and tillage practices. Samples of upper leaves and lower leaves were collected separately. The samples were either not washed, washed with deionized water, or washed with detergent solution. After drying, grinding, and digesting, the samples were analyzed for Al, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu). For all crop plants and conditions studied, there was no effect on measured N, P, K, Ca, Mg, Mn, Zn, or Cu concentrations, but measured Al and Fe concentrations were influenced by washing. In general, washing had a greater effect on Al analyses than on Fe analyses. Soybean samples were most affected by washing, while wheat samples seemed to be least affected. The results reflected greater contamination of lower leaves than upper leaves. Decontamination procedures appear necessary prior to Al and Fe analyses of field-grown crop plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02140668
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  • 90
    Digitale Medien
    Digitale Medien
    Distribution of N, P, K, Ca, Mg, S, Zn, Fe, Mn and Cu in groundnut (1985)
    Springer
    Plant and soil 84 (1985), S. 269-273 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Calcium ; Copper ; Groundnut ; Iron ; Kernel ; Kharif ; Leaflet ; Magnesium ; Manganese ; Nitrogen ; Petiole ; Phosphorus ; Potassium ; Root ; Shell ; Stem ; Sulphur ; Summer ; Zinc
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Concentration of N, P, K, Ca, Mg and S in summer groundnut crop was higher than in kharif while Zn, Fe, Mn and Cu contents were higher in summer crop. Kernel's N, P and Zn; Leaflet's Ca and Mn; Stem's K and Fe; Root's S and Cu and Petiole's Mg contents were highest. Shell's N, P, K, Mg, S, Zn and Cu; Kernel's Ca, Fe and Mn contents were the least. N, P, K, S, Zn and Cu concentrations decreased linearly as the crop grew. Ca, Mg, Fe and Mn concentrations did not display any distinct pattern. Ca concentration was positively correlated with pod yield in both the seasons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02143189
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  • 91
    Digitale Medien
    Digitale Medien
    Nutrient proportions in foliage of semi-mature loblolly pine (1985)
    Springer
    Plant and soil 86 (1985), S. 27-34 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Loblolly pine ; Nitrogen ; Nutrient ratios ; Phosphorus ; Pinus taeda
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Nitrogen and phosphorus limitations to growth are common in many loblolly pine (Pinus taeda) stands. Interactions of these nutrients may complicate interpretation of foliar nutrient analysis for predicting response to forest fertilization. Proportions of foliar nutrient concentrations (and the changes in these proportions following fertilization) were examined in 36 semi-mature loblolly pine plantations in the southeastern United States. Mean proportions of nutrient concentrations (N∶P∶K∶Ca∶Mg) for non-fertilized stands were 100∶9.3∶36.5∶17.2∶9.2. Potassium and phosphorus were higher. Nitrogen fertilization generally decreased the P∶N ratio and enhanced growth, indicating a nitrogen deficiency in most stands under study. Additions of nitrogen and phosphorus together yielded a significant increase in the P∶N ratio. Effects of fertilization effects on other nutrient concentration ratios were also examined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02185022
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  • 92
    Digitale Medien
    Digitale Medien
    Phosphorus accumulation by lignotubers of jarrah (Eucalyptus marginata Donn ex Sm.) seedlings grown in a range of soils (1985)
    Springer
    Plant and soil 86 (1985), S. 225-232 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Eucalyptus marginata ; Lignotuber ; Nitrogen ; Phosphorus ; Seedlings ; Virgin soils X-ray probe microanalysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Jarrah seedlings were grown in six virgin Western Australian soils for up to 27 months. Lignotubers were produced in all soils and formed 10–16% of plant dry weight. The phosphorus concentration in the lignotuber (250–800 μg g−1) was nearly twice that in the stem and roots. The lignotuber contained 10–30% of total plant phosphorus and like the leaves was a sink for phosphorus. In one lateritic soil the phosphorus concentrations of lignotuber and stem barks were similar. However, in the same plants the concentration of phosphorus in the lignotuber wood was five times the phosphorus concentration in stem wood. Hence both lignotuber bark and sap wood in young jarrah seedlings are storage sites for phosphorus. X-ray probe analysis showed that wood phosphorus was associated with the ray parenchyma. Unlike phosphorus, nitrogen did not accumulate in the lignotuber and the concentrations of nitrogen were similar for roots, lignotubers and stems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02182897
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  • 93
    Digitale Medien
    Digitale Medien
    Effect of zinc fertilization on the mineral nutrition of rices differing in tolerance to zinc deficiency (1985)
    Springer
    Plant and soil 87 (1985), S. 319-327 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Copper ; Iron ; Magnesium ; Manganese ; Mineral nutrition ; Nutrient translocation ; Phosphorus ; Rice ; Varietal tolerance ; Zinc ; Zinc fertilization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The effects of four Zn levels on the electrochemical and chemical properties of the soil solution, and on the growth and mineral nutrition of two rice varieties (IR26 and IR34) differing in tolerance to Zn deficiency were studied in the greenhouse using Zn-deficient soils from two locations. A similar experiment was conducted in culture solution to check how Zn addition affects translocation of other nutrients. In both soil and culture solution, plant Zn concentrations alone was not enough to account for varietal tolerance to Zn deficiency. Comparison of nutrient to Zn and shoot to root ratios of nutrients was more useful in determining the possible mechanism of varietal tolerance. IR 34 appeared to tolerate the disorder due to its lower Zn requirement, more efficient Zn translocation and ability to maintain lower Fe/Zn, Cu/Zn, Mg/Zn and P/Zn ratios in the shoot than the more susceptible variety, IR26. This was shown to be due to decreased translocation of Fe, Mg and P to shoots and decreased absorption of Cu by the root in IR34 in culture solution studies. Adding Zn further reduces translocation or absorption of these nutrients and depending on the nutrient supply of the soil, could cause deficiencies or mineral imbalances, especially of Fe, Cu, and P. These observed varietal differences regarding Zn requirement and the interaction of Zn with absorption and translocation of plant nutrients necessitates revision of recommendations for Zn fertilization. There is an inevitable need for Zn application in severely Zn-deficient soils regardless of rice variety. But on marginally Zn-deficient soils especially those low in Fe, Cu, or P, Zn fertilization is not advisable when resistant rice varieties are used.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02181899
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  • 94
    Digitale Medien
    Digitale Medien
    Organocobalt Compounds in the Synthesis of Pyridines-An Example of Structure-Effectivity Relationships in Homogeneous CatalýsisBased on the work of Helmut Bönnemann, Werner Brijoux, Rainer Brinkmann, Willi Meurers, Michael Radermacher, and Stephan Wendel. The author thanks his co-workers for their important contributions to this work.Dedicated to Professor Günther Wilke on the occasion of his 60th bithday (1985)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 24 (1985), S. 248-262 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Organocobalt compounds ; Pyridines ; Catalysis ; Homogeneous catalysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The cocyclization of alkynes with cyano compounds using organocobalt catalysts of the type [YCoL] has evolved into a versatile and technically useful method for synthesizing pyridine and its derivatives. An important advance came with the realization that the organo group Y remains attached to the cobalt throughout the catalytic cycle. This opened up the possibility of optimizing the catalyst by varying the controlling ligand Y.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198502481
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  • 95
    Digitale Medien
    Digitale Medien
    Catalytic Synthesis of Organolithium and Organomagnesium Compounds and of Lithium and Magnesium Hydrides - Applications in Organic Synthesis and Hydrogen StorageBased on work carried out by Ekkehard Bartmann, Borislav Bogdanović, Alexis Cordi, Gudrun Koppetsch, Oleg Kuzmin, Shih-tsien Liao, Paolo Locatelli, Meenakshi Maruthamuthu, Klaus Schlichte, Manfred Schwickardi, Peter Sikorsky, Bernd Spliethoff, Halszka Stepowska, Bernd Wermeckes, Uwe Westeppe, and Ursula Wilczok. The author thanks these co-workers for their dedicated and enthusiastic assistance.Dedicated to Professor Günther Wilke on the occasion of his 60th bithday (1985)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 24 (1985), S. 262-273 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Organomagnesium compounds ; Magnesium hydrides ; Hydrides ; Hydrogen storage ; Catalysis ; Organolithium compounds ; Lithium hydrides ; Energy storage ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A recent development in homogeneous catalysis is the discovery of catalysts that are active for the lithiation of 1-alkenes to alkenyllithium compounds and lithium hydride as well as for the hydrogenation of lithium and magnesium under mild conditions. The catalytically prepared magnesium hydride is highly reactive and adds to 1-alkenes to give diorganomagnesium compounds and can also be used in the preparation of, for example, silane and “active” magnesium. The use of metal hydrides in hydrogen storage is discussed: hydrogenation/dehydrogenation experiments show that the catalytically prepared magnesium hydride (which can be doped with a second metal) can be used as a high-temperature hydrogen storage material.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198502621
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  • 96
    Digitale Medien
    Digitale Medien
    η3-Allylpalladium CompoundsBased on work carried out by B. Henc, P. W. Jolly, T. Joswig, B. Raspel, G. Schenker, K. P. Schick, and H. Trinh.Dedicated to Professor Günther Wilke on the occasion of his 60th bithday (1985)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 24 (1985), S. 283-295 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Allylpalladium compounds ; Palladium ; Catalysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The use of transition-metal complexes as homogeneous catalysts for the production of organic chemicals is of considerable industrial significance. Although palladium complexes have not attained the same importance as, for example, those of rhodium or cobalt, palladium is nonetheless one of the most versatile metals for synthetic organic purposes. An understanding of the role played by the metal in these reactions is essential for their optimal utilization. This necessarily entails a detailed study of the chemistry of the palladium-carbon bond. In this article we concentrate on η3-allylpalladium complexes, which are frequently involved as intermediates in the Pd-catalyzed transformations of dienes. The study of their behavior gives a deeper insight into the individual steps of a catalytic cycle.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.198502831
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  • 97
    Digitale Medien
    Digitale Medien
    Complexes of Tetradentate Ligands Containing Phosphorus and ArsenicAdapted from a Plenary Lecture at the General Meeting of the Gesellschaft Deutscher Chemiker on Sept. 10th, 1963 in Heidelberg (Germany). (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 453-460 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Tetradentate ligands ; P ligands ; Arsenic ligands ; Phosphorus ; Arsenic ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The effect of ligand shape on coordination numbers and geometry of coordination compounds has been studied using two tetradentate ligands containing phosphorus and arsenic. These tend to form five-coordinate complexes with trigonal bipyramidal structure [Fe(II), Co(I), Co(II), Rh(I), Ni(II), Pd(II), Pt(II)], but can also form six-coordinate complexes with octahedral structure [Fe(II), Ru(II), Os(II), Co(III), Rh(III), Pd(IV), Pt(IV)]. The magnetic properties and the stereochemistry of the complexes are explained by ligand field theory which predicts that, for metal ions with d6-electronic configuration, a low overall field strength should favor the formation of five-coordinate paramagnetic complexes while a high overall field strength should favor the formation of six-coordinate diamagnetic complexes. - This work provides further indication that the tendency of polydentate ligands to use all the potential donor atoms is not as pronounced as is generally believed. This is shown by the isolation of chromium(III) complexes in which the tetradentate ligands are, in fact, acting as tridentate, and by the isolation of mercury(II) complexes where only two of the four donor atoms of the polydentate ligand are actually bonded to the central metal atom.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196404531
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  • 98
    Digitale Medien
    Digitale Medien
    Proton Transfer, Acid-Base Catalysis, and Enzymatic Hydrolysis. Part I: ELEMENTARY PROCESSESPart II (Catalytic Mechanisms) will appear shortly in this journal.Dedicated to Dr. W. Foerst on the occasion of his 65th birthday (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 1-19 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Proton transfer ; Catalysis ; Enzyme catalysis ; Hydrolysis ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The proton occupies a special position as a promoter and mediator in chemical reactions occurring in solution. Many reactions in organic chemistry are catalysed by acids or bases; likewise, most enzymes contain active groups which promote acid-base catalysis. To understand the reaction mechanisms involved, it is necessary to identify the elementary steps as well as their course in time. Systematic investigation of these elementary steps as well as their course in time. Systematic investigation of these elementary steps has become possible only with the development of new methods for studying very fast reactions. The present paper reviews the information obtained in this type of investigation. The result is a relatively complete picture of the elementary proton transfer mechanisms and a comprehensive description of the modes and laws of acid-base and enzymatic catalysis.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196400011
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  • 99
    Digitale Medien
    Digitale Medien
    The Mechanism of the Action of Organometallic CatalystsDedicated to Prof. Dr. Karl Winnacker on the occasion of his 60th birthday. (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 93-101 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Organometallic catalysts ; Catalysis ; Reaction mechanisms ; Lithium ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Kinetic investigations of the polyreaction of isoprene with organolithium compounds as initiators in n-heptane as solvent indicate the following sequence of reactions: 1. formation of an adduct between a monomeric form of the organolithium compound and the isoprene and 2. reaction of this adduct with an associated form of the organolithium compound with insertion of the isoprene. The adduct formation is considered to be due to chemisorption, and proof of such chemisorption of a monomer (ethylene) is also demonstrated for a homogeneous Ziegler-type catalyst. All the reactions can be formulated in the form of cyclic structures with electron-deficient character. Postulation of such ring structures explains the surprising values obtained for the frequency factors and equilibrium constants.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196400931
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  • 100
    Digitale Medien
    Digitale Medien
    Coordination Chemistry and Catalysis. Investigations on the Synthesis of Cyclooctatetraene by the Method of W. Reppe (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 185-191 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Coordination modes ; Catalysis ; Cyclooctatetraenes ; Reppe chemistry ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The relationship between the structure and the catalytic activity of nickel(II) complexes in the synthesis of cyclooctatetraene by the method of W. Reppe is discussed. The cyclotetramerization of acetylene takes place within labile Ni(II)-acetylene π-complexes. Inhibition tests have made it probable that four molecules of acetylene are grouped around the nickel ion in the transition state, in a configuration which favors the formation of the eight-membered ring.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196401851
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