Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 19 (1995), S. 141-147 
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Biomass C:N ratio Acidification ; Beech forest ; Soil organic C ; Total N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soils from 38 German forest sites, dominated by beech trees (Fagus sylvatica L.) were sampled to a depth of about 10 cm after careful removal of overlying organic layers. Microbial biomass N and C were measured by fumigation-extraction. The pH of the soils varied between 3.5 and 8.3, covering a wide range of cation exchange capacity, organic C, total N, and soil C:N values. Maximum biomass C and biomass N contents were 2116 μg C m-2 and 347 μg N m-2, while minimum contents were 317 and 30 μg m-2, respectively. Microbial biomass N and C were closely correlated. Large variations in microbial biomass C:N ratios were observed (between 5.4 and 17.3, mean 7.7), indicating that no simple relationship exists between these two parameters. The frequency distribution of the parameters for C and N availability to the microflora divided the soils into two subgroups (with the exception of one soil): (1) microbial: organic C〉12 mg g-1, microbial:total N〉28 mg g-1 (n=23), a group with high C and N availability, and (2) microbial:organic C≤12 mg g-1, microbial:total N≦28 mg g-1 (n=14), a group with low C and N availability. With the exception of a periodically waterlogged soil, the pH of all soils belonging to subgroup 2 was below 5.0 and the soil C:N ratios were comparatively high. Within these two subgroups no significant correlation between the microbial C:N ratio and soil pH or any other parameter measured was found. The data suggest that above a certain threshold (pH 5.0) microbial C:N values vary within a very small range over a wide range of pH values. Below this threshold, in contrast, the range of microbial C:N values becomes very large.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 19 (1995), S. 215-219 
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Acidification ; Beech forest ; Soil organic C ; Total P ; Fagus sylvatica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thirty-eight soils from forest sites in central Germany dominated by beech trees (Fagus sylvatica L.) were sampled to a depth of about 10 cm after careful removal of the overlying organic layers. Microbial biomass P was estimated by the fumigation — extraction method, measuring the increase in NaHCO3-extractable phosphate. The size of the microbial P pool varied between 17.7 and 174.3 μg P g-1 soil and was on average more than seven times larger than NaHCO3-extractable phosphate. Microbial P was positively correlated with soil organic C and total P, reflecting the importance of soil organic matter as a P source. The mean microbial P concentration was 13.1% of total P, varying in most soils between 6 and 18. Microbial P and microbial C were significantly correlated with each other and had a mean ratio of 14.3. A wide (5.1–26.3) microbial C: P ratio indicates that there is no simple relatinship between these two parameters. The microbial C: P ratio showed strong and positive correlations with soil pH and cation exchange capacity.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 11 (1991), S. 151-156 
    ISSN: 1432-0789
    Keywords: Acid rain ; Mesofauna ; Decomposition ; Beech forest ; Calcareous soil ; Litterbag ; 14C-labelled beech leaf litter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of simulated acid rain on litter decomposition in a calcareous soil (pHH 2 O 5.8) were studied. Litterbags (45 μm and 1 mm mesh size) containing freshly fallen beech leaf litter were exposed to different concentrations of acid in a beech forest on limestone (Göttinger Wald. Germany) for 1 year. Loss of C, the ash content, and CO2−C production were measured at the end of the experiment. Further tests measured the ability of the litter-colonizing microflora to metabolize 14C-labelled beech leaf litter and hyphae. The simulated acid rain strongly reduced CO2−C and 14CO2−C production in the litter. This depression in production was very strong when the input of protons was 1.5 times greater than the normal acid deposition, but comparatively low when the input was 32 times greater. acid deposition may thus cause a very strong accumulation of primary and secondary C compounds in the litter layer of base-rich soils, even with a moderate increase in proton input. The presence of mesofauna significantly reduced the ability of the acid rain to inhibit C mineralization. The ash content to the 1-mm litterbags indicated that this was largely due to transport of base-rich mineral soil into the litter.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 12 (1992), S. 253-260 
    ISSN: 1432-0789
    Keywords: Mesofauna ; Microbial biomass ; Litterbag ; Beech forest ; Moder ; Lime
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In December 1988, litterbags (mesh size 45 or 1000 μm) were exposed in the organic layer of a limed and unlimed moder soil under beech forest in the Solling area (Germany). At both sites, substrata from the L1, L2, F1, F2 and from the H Layer were sampled shortly before the beginning of the experiment, defaunated, filled separately into litterbags and replaced in the respective horizons in the field. Litterbags were retrieved on three sampling dates (May, September, and November 1989). The soil microbial biomass was estimated by means of the fumigation extraction method. The results show that the effects of excluding mesofauna from the 45-μm litterbags were different in different horizons, on different sampling dates and in different study sites. Calculation of the “average” effect from the three sampling dates revealed that mesofauna exclusion reduced the microbial biomass C at both sites. It was concluded from horizon- and season-specific differences between the two litterbag treatments that a depression in microbial biomass C in the organic layer of a moder soil by mesofaunal grazers is confined to situations where environmental conditions cause strong feeding pressure and when the microflora is exposed to environmental stress.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 15 (1993), S. 301-307 
    ISSN: 1432-0789
    Keywords: Mesofauna ; Amino sugar ; Soil micro-flora ; Beech forest ; Moder ; Lime
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In December 1988, litter bags (mesh size: 45 and 1000 μm) were exposed in the organic layer of unlimed and limed moder soil under beech forest in the Solling area of Germany. Bags were retrieved on three sampling dates (May, September, and November 1989) and amounts (g m-2) of glucosamine and galactosamine were determined. Horizon-specific differences generally explained by far the largest part of the treatment variance. In the substrate sampled in December 1988 from the unlimed area glucosamine increased by a factor of 11.8 from the L 1 layer to the H layer and galactosamine by a factor of 15.9. With the exception of the F2 layer, the hexosamine amounts found in the limed substrate sampled in December 1988 were higher in all horizons than in the corresponding horizons sampled from the unlimed area. Exclusion of mesofauna from the 45-μm litter bags generally reduced the level of amino sugars at both sites. The difference between the two mesh sizes was most pronounced in the lowermost horizons (F2 and H) and quite small in the upper horizons. The exclusion of mesofauna significantly increased the glucosamine: galactosamine ratio in the two L layers of the unlimed soil on all sampling dates. Seasonal fluctuations suggested that the actual amino sugar content of the organic layer was essentially the function of two components, the first reflecting long-term accumulation of microbial metabo-lites, and the second reflecting short term fluctuations in the microbial colonization of various C sources together with spatial and temporal differences in the ability of the microflora to produce and to decompose hexosamines. The results of this study show that the mesofauna in the beech forest soils investigated significantly affected both the amino sugar components measured, and thus stimulated the accumulation of one of the most important N pools in forest soils.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 111 (1978), S. 639-660 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A New Synthesis Principle for Furane Derivatives, II: Fragmentation and Recyclising Condensation of 1,3-Dioxolane-4-ylium IonsThermolysis of 2,2-dialkyl-4-benzoyloxy-1,3-dioxolanes (3), as well as protonation of 2,2-dialkyl-4-methylene-1,3-dioxolanes (9) and 2,2-dialkyl-4-methyl-1,3-dioxoles (10) primarily lead to 1,3-dioxolane-4-ylium ions (1) which fragmentate under the reaction conditions and recyclisingly condensate to furane derivatives.  -  The mechanism of this reaction is investigated and the preparative scope is traced out by variation of substituents. Treatment of 2-alkyl-4-benzoyloxy-2(2-bromoalkyl)-1,3-dioxolanes with zine leads via a complementary anionic pathway to corresponding furane derivatives.
    Notes: Die Thermolyse von 2,2-Dialkyl-4-benzoyloxy-1,3-dioxolanen (3) sowie die Protonierung von 2,2-Dialkyl-4-methylen-1,3-dioxolanen (9) und 2,2-Dialkyl-4-methyl-1,3-dioxolen (10) führen primär zu 1,3-Dioxolan-4-ylium-Ionen (1), die unter den Reaktionsbedingungen fragmentieren und recyclisierend zu Furanderivaten kondensieren.  -  Der Mechanismus dieser Reaktion wird untersucht und die präparative Leistungsfähigkeit durch Substituentenvariation abgesteckt. Die Behandlung von 2-Alkyl-4-benzoyloxy-2-(2-bromalkyl)-1,3-dioxolanen mit Zink führt auf einem komplementären anionischen Weg zu korrespondierenden Furanderivaten.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 1572-1582 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Benzonitrile as a 6-Electron Donor Ligand: The Clusters Fe3(CO)9(μ3(η2)-NCC6H5) and Fe4(CO)12(μ4(η2)-NCC6H5)The reaction of Fe3(CO)12 with benzonitrile in the presence of hydrogen leads to the benzonitrile complexes Fe3(CO)9(μ3(η2)-NCC6H5) (1a) and Fe4(CO)12(μ4(η2)-NCC6H5) (2). Their structures were determined crystallographically. The benzonitrile ligand is coordinated to the iron atoms formally via on „s̰-bond“ and two „π-bonds“ in 1a, and via three s̰-bonds and one π-bond in 2.
    Notes: Die Reaktion von Fe3(CO)12 mit Benzonitril in Anwesenheit von Wasserstoff führt zu den beiden Benzonitril-Komplexen Fe3(CO)9(μ3(μ2)-NCC6H5) (1a) und Fe4(CO)12(μ4(η2)-NCC6H5) (2). Ihre Strukturen wurden kristallographisch aufgeklärt. Der Benzonitril-Ligand ist in 1a formal über eine „s̰-Bindung“ und zwei „π-Bindungen“, in 2 über drei s̰-Bindungen und eine π-Bindung an die Eisenatome koordiniert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1219-1239 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cluster Construction: Formation of Phosphinidene Bridged Iron and Cobalt Clusters from Fe2(CO)6(PHR)2The PH functional dinuclear complexes Fe2(CO)6(PHR)2 (1, R = Me, t-Bu, Ph, p-Tol) contain the (CO)3Fe and PHR units in such an arrangement as to make possible the attachment of further carbonylmetal units with formation of phosphinidene bridged clusters. Accordingly they react with Co2(CO)8 to form Fe2Co(CO)9(μ2-PHR)(μ3-PR) (2, R = Me, Ph) and Fe2Co2(CO)11(μ4-PR)2 (3, R = Me, Ph) of which the clusters 2 are not intermediates on the way to 3. From 1 and Fe3(CO)12, depending on the reaction conditions, Fe3(CO)9(μ3-PR)2 (4, R = Me, Ph, p-Tol), Fe4(CO)11(μ4-PR)2 (5, R = Me, t-Bu, Ph, p-Tol), and Fe4(CO)12(μ4-PR)2 (6, R = Me, t-Bu, Ph, p-Tol) are formed. The Fe4 clusters 5 are also formed from Fe3(CO)12 and the Fe3 clusters 4. Conversely the clusters 5 yield the clusters 4 by thermal degradation, whereby also the P—t-Bu compound 4 becomes accessible. The saturated Fe4 clusters 6 and the unsaturated Fe4 clusters 5 can be converted into one another in vacuum and by addition of CO, respectively. The structures of one compound each of the Fe2Co clusters 2, the Fe2Co2 clusters 3 (two isomers), and the Fe4 clusters 5 were determined crystallographically.
    Notes: Die PH-funktionellen Zweikernkomplexe Fe2(CO)6(PHR)2 (1, R = Me, t-Bu, Ph, p-Tol) enthalten die (CO)3Fe- und PHR-Einheiten in einer Anordnung, die den Anbau weiterer Carbonyl-metall-Einheiten unter Bildung Phosphiniden-verbrückter Cluster möglich erscheinen lassen. Sie reagieren demgemäß mit Co2(CO)8 Zu Fe2Co(CO)9(μ3-PHR)(μ3-PR) (2, R = Me, Ph) und Fe2Co2(CO)11(μ4-PR)2 (3, R = Me, Ph), wobei die Cluster 2 keine Zwischenstufen auf dem Wege zu 3 sind. Aus 1 und Fe3(CO)12 entstehen je nach den Bedingungen Fe3(CO)9(μ3-PR)2 (4, R = Me, Ph, p-Tol), Fe4(CO)11(μ4-PR)2 (5, R = Me, t-Bu, Ph, p-Tol) und Fe4(CO)12(μ4-PR)2 (6, R = Me, t-Bu, Ph, p-Tol). Die Fe4-Cluster 5 bilden sich auch aus Fe3(CO)12 und den Fe3-Clustern 4. Umgekehrt liefern die Cluster 5 durch thermischen Abbau die Cluster 4, wodurch auch die P—t-Bu-Verbindung 4 zugänglich wird. Die gesättigten Fe4-Cluster 6 und die ungesättigten Fe4-Cluster 5 sind im Vakuum bzw. durch CO-Zugabe leicht ineinander zu überführen. Von je einem Vertreter der Fe2Co-Cluster 2, der Fe2Co2-Cluster 3 (2 Isomere) und der Fe4-Cluster 5 wurde kristallographisch die Struktur bestimmt.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 95 (1962), S. 1237-1244 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vom [2-Acetyl-phenyl]-selenocyanat ausgehend, werden neue offene und cyclische Organoselen-Verbindungen-insbesondere Selenoflavanone dargestellt. Die Selenoflavanone zeigen eine gegenüber den Schwefelisologen verstärkte Tendenz zum Übergang vom heterocyclischen Sechs- zum Fünfring.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 3 (1989), S. 329-342 
    ISSN: 0886-9383
    Keywords: Calibration ; Robust regression ; Iteratively reweighted least squares ; M-estimator ; Monte Carlo simulations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By means of Monte Carlo simulations a comparison has been made between ordinary least squares regression and robust regression. The robust regression procedure is based on the Huber estimate and is computed by means of the iteratively reweighted least squares algorithm. The performance of both procedures has been evaluated for estimation of the parameters of a calibration function and for determination of the concentration of unknown samples. The influence of the distributional characteristics skewness and kurtosis has been studied, and the number of measurements used for constructing the calibration curve has also been taken into account. Under certain conditions robust regression offers an advantage over least squares regression.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...