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  • 1
    Electronic Resource
    Electronic Resource
    Experiments on the control capacity of stomata of Picea abies (L.) Karst. after fumigation with ozone and in environmentally damaged material (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 14 (1991), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. With the aid of specifically designed potometer experiments, it is shown that, after ozone fumigation, twigs transpiring in gas exchange chambers show poor water balance in decreasing humidity. The quotient of water uptake to water loss never falls below 0.9 in healthy material because of the control capacity of the stomata. In twigs from a tree fumigated with ozone irregular and delayed stomatal closure results in values of 〈 0.5 or even lower, depending on the degree of damage. As a result, in dry air, the transpiration rates of fumigated twigs often fall far below those of the control material, even if they were higher than the latter in humid air. In analogous experiments, the difference in behaviour between twigs of densely (‘healthy’) and sparsely needled (‘damaged’) trees from the natural stand is comparable to the difference between controls and ozone-fumigated trees in most respects. In soil that is more or less dried out and after the best possible saturation of the twigs during the night, the transpiration rates of fumigated trees increase fairly strongly in the humid chamber air at dawn, but finally decrease more or less suddenly to lower values than in the controls. The results are placed in the context of the basic research on plant water relations and compared with histological changes in the stomatal apparatus after a period of fumigation as described earlier. Therefore, long-term effects of pollution can be explained as a specific distrubance of hydroregulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1991.tb01334.x
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  • 2
    Electronic Resource
    Electronic Resource
    Experiments on the water budget of densely and sparsely needled spruces [Picea abies (L.) Karst.] in a declining stand (1991)
    Springer
    Trees 5 (1991), S. 164-170 
    Details
    ISSN: 1432-2285
    Keywords: Forest decline ; Osmotic potential ; Picea abies ; Water content ; Water potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The osmotic potentials of needles were compared from numerous trees that had been classified according to needle loss along an altitude profile. With the increasing degree of damage of the trees, the maximum and minimum values deviated more strongly above and below the common mean of all samples. The level of water content of the needles unequivocally reflected the vitality of the trees. Experiments covering a whole vegetation period were performed on a tree pair selected from a natural stand. They were designed to demonstrate differences in water balance between the “healthy” and “damaged” state of the trees. For the “damaged” tree, measurements of the water potentials of single needles showed a greater reduction of potential during the course of the day compared to the “healthy” tree. Recovery in the evenings was slower and often incomplete. The osmotic potentials of “damaged” and “healthy” shoots measured in individual needles also differed both predawn and especially after transpiration stress. Depending on weather and soil desiccation, the differences were more or less pronounced. In the “damaged” tree, the rises in potential after saturation of the twigs fell far short of the “healthy” tree. Reduction of water potential, osmotic potential and relative water content under comparable stress conditions suggest a reduced tolerance of drought by damaged trees. In the context of earlier experiments this result was ascribed to a lack of stomatal control, and long-term pollution effects were thus explained as a specific disturbance of hydroregulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00204339
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  • 3
    Electronic Resource
    Electronic Resource
    Histological examination of spruce needles from a long-term gas exchange experiment in pure and polluted air in the field (1992)
    Springer
    Trees 6 (1992), S. 186-194 
    Details
    ISSN: 1432-2285
    Keywords: Air pollutants ; Bundle sheath ; Picea abies ; Stomata ; UV absorbance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary At the end of a 4-year period of gas exchange measurements in a natural stand in the Lower Bavarian Forest, needles of an adult spruce [Picea abies (L.) Karst.] were harvested from two chambers, one with pure air and the other with ambient air. The needles were examined as to their histological properties in the stomatal apparatus and in the bundle sheath. In needles from the polluted air UV absorbance at 280 nm was decreased in the walls of the stomatal apparatus. Simultaneously, the deposition of compounds with an absorption maximum at 310 nm increased within the encrusted plate-like thickenings of the subsidiary cells. The contents of the lumina of hypodermal cells and of the bundle sheath exhibited a greater degree of autofluorescence in ambient-air material than in pure-air leaf organs. Differences between needles exposed to pure and polluted air are gradual. The “damaged” condition is rare in pure air, common in polluted air. The needles from outside the chambers occupied an intermediate position between pure-air and ambient-air needles. This fact is traced to an unnaturally high pollutant load in the liquid phase of the needle surfaces within the ambient-air chamber because in order to compensate pollutant losses within the system, SO2 and O3 were added even during periods of irrigation. The reduction of absorption capacity at 280 nm in the walls of the stomatal apparatus is attributed to destruction of lignin due to the high reactivity of the pollutants in the liquid phase on the damp needle surface. The importance of delignification with regard to hydroregulation is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224334
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of air pollution on the mechanism of stomatal control (1992)
    Springer
    Trees 7 (1992), S. 12-25 
    Details
    ISSN: 1432-2285
    Keywords: Air pollution ; Drought stress ; Forest decline ; Gas exchange measurements ; Stomatal control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A long-term field experiment permanently measuring gas exchange in the top of a 70-year-old spruce, continued for through the 1990 growing season. Two gas exchange chambers were run simultaneously under identical climatic conditions. One of two similar twigs was exposed to ambient air whereas the other received pure air. These experiments aimed to examine the ability of the stomata to control water balance, comparing pure and ambient air. This was done not only in natural climatic conditions but also in experimental, specifically maintained stress situations. Special care was taken to ensure that only steady state values of stomatal responses are related to the environmental stimuli. During a drought period lasting several weeks, overshooting transpiration values were documented for the ambient air. The two twigs do not merely differ in their control capacity, but the behaviour of the stomata in ambient air deviates from the “norm”. The increasingly uncontrolled water losses during the drought period have a negative effect on photosynthetic capacity. The influence of water deficit on stomatal response to other environmental factors (light, CO2) is shown. Due to deficient control quality of the stomata lower stress tolerance in the face of drought is suggested in ambient air as compared with pure air. By tracing dysfunctions to structural changes in the cell walls of the stomatal apparatus, a mechanism is described explaining forest decline under the combined influence of air pollutants and drought stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225227
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  • 5
    Electronic Resource
    Electronic Resource
    Zur Reaktionsweise aromatischer Spirophosphorane (1964)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 97 (1964), S. 747-768 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mit der „Tosylimin-Methodik“ lassen sich Triarylphosphine bequem und in befriedigenden Ausbeuten zu Pentaarylphosphoranen abwandeln. Die Spiroderivate VI, VIII, XI und XXV gingen beim Erhitzen über ihre Schmelzpunkte eine Ringerweiterung zu o-Quaterphenylen-(2.2‴)-phosphinen ein. Experimentelle Befunde luden dazu ein, eine Korrelation mit den Symmetrieelementen der möglichen Raumanordnungen herzustellen, um - allerdings mit Vorbehalt - den Konfigurationstypus der Pentaarylphosphorane zu ermitteln.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19640970319
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  • 6
    Electronic Resource
    Electronic Resource
    Die Polymerisation des Coniferylalkohols durch Säure (1964)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 97 (1964), S. 903-908 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Am Coniferylalkohol veranalßt Säure wie bei dem Zimtalkohol eine lineare Dimerisation; dabei entsteht I. Durch Allylumlagerung bricht die Reaktion ab unter Bildung von II. Ein isoliertes Trimerisat V hat denselben Kettenabschluß und ein Ätherbindung zwischen dem ersten und zweiten Glied. Als Zwischenprodukt ist ein ätherartiges Dimeres IV anzunehmen, das zum Trimeren aufgebaut wird. Durch den Kettenabschluß entstehen p-Hydroxy-benzylalkohole, die sich am weiteren Aufbau durch Polykondensation beteiligen. Schließlich entstehen unlösliche Produkte. - Durch Synthese wurde ein dimerer Coniferyl-alkohol IX hergestellt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19640970339
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  • 7
    Electronic Resource
    Electronic Resource
    NMR Spectroscopy of Organolithium Compounds, XV[1]. Two-Dimensional 6Li,1H-NMR Shift Correlation by Multiple Quantum Spectroscopy and Polarization Transfer: New Tools for Structural Research in the Field of Organolithium Compounds (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2747-2751 
    Details
    ISSN: 0009-2940
    Keywords: Polylithium compounds ; NMR, 6Li ; Shift correlation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sizable scalar 6Li,1H spin-spin coupling constants have been observed for the new dilithio compound (Z)-2-lithio-1-(o-lithiophenyl)ethene (3) which allow an assignment of the two non-equivalent 6Li resonance signals measured for the dimer of 3. Two-dimensional 6Li,1H shift correlation experiments based on multiple quantum spectroscopy as well as on polarization transfer are introduced as new tools for structural research in the field of organolithium compounds.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931261226
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  • 8
    Electronic Resource
    Electronic Resource
    Polylithiumorganische Verbindungen, XVI. 1,4-Disila[6]radialene: Aktivierungsparameter der Sessel-Twist-Inversion und analytische Enantiomerentrennung der Twist-Konformeren (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2033-2036 
    Details
    ISSN: 0009-2940
    Keywords: 1,4-Disila[6]radialenes ; [6] Radialenes ; Chair-twist inversion, kinetic measurements of ; Twist conformers, separation of enantiomers of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polylithiumorganic Compounds, XVI. - 1,4-Disila[6]radialenes: Activation. Parameters of the Chair-Twist Inversion and Analytical Separation of the Enantiomers of the Twist ConformersKinetic measurements of the chair-twist inversion of the 1,4-disila[6]radialenes 2 - 4 have been performed at four different temperatures, respectively. The entropies of activation are found to be negative. While the chair conformers of the radialenes are achiral as expected, the enantiomers of the three twist conformers could be separated by HPLC on an optically active stationary phase.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911240925
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  • 9
    Electronic Resource
    Electronic Resource
    Versuche zur Umlagerung von Cyclobutyl- in 3-Butenyl-Anionen: Endocyclische Ringöffnung bei der Reaktion von (3,3-Diphenyl-1-vinylcyclobutyl)methylether mit Alkalimetallen - anionisch oder radikalisch? (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 185-192 
    Details
    ISSN: 0009-2940
    Keywords: Ring-chain equilibria of carbanions and radicals / Cyclobutyl anion, stability of / Endocyclic ring opening of cyclobutyl radicals / Ziegler ether cleavage with lithium and sodium / C-C σ-bond cleavage with lithium metal ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Attempted Rearrangement of Cyclobutyl Anions to 3-Butenyl Anions: Endocyclic Ring Opening upon Reaction of 3.3-Diphenyl-1-vinylcyclobutyl Methyl Ether with Alkali Metals - via Anions or Radicals?The reaction of the title compound 16 with lithium or sodium in THF yields mainly the open-chain E/Z isomeric trianions 31 ⇌ 32 besides the expected cyclobutyl anion 10. The endocyclic ring opening takes place via the radical intermediate 28 primarily yielding a butadiene derivative 29, which is then further reduced. The anion 10 - prepared independently by deprotonation of the corresponding hydrocarbon 18 - does not rearrange. On investigating side reactions it was discovered that 4,4-diphenyl-1-butene derivatives treated with lithium in THF undergo C-C bond cleavage affording diphenyl-methyllithium in good yields.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230131
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  • 10
    Electronic Resource
    Electronic Resource
    Studien zur enantio- und diastereoselektiven α-Metallierung prochiraler Sulfoxide mit (+)-Menthyllithium (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2489-2498 
    Details
    ISSN: 0009-2940
    Keywords: (+)-Menthyllithium, stereoselective metallation with ; Prochiral sulfoxides, enantio- and diastereoselective α-deprotonation of ; 2-Bornyllithium, content of isobornyllithium in ; Racemization, mechanism by intermolecular transmetallation ; e.e., temperature dependence of ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantio- and Diastereoselective α-Metallation of Prochiral Sulfoxides by (+)-MenthyllithiumSix out of ten prochiral dialkyl sulfoxides 3 with diastereotopic α methylene protons were stereoselectively metallated by (+)-menthyllithium (11) to yield two diastereomeric pairs of enriched enantiomers 29 after the reaction with benzophenone. The maximum e.e. was 40%. Dicyclohexyl sulfoxide (3c) was deprotonated enantioselectively with an e.e. of 30%. 2-Bornyllithium (21) was unsuccessful as a chiral base and was shown for the first time to contain 4% of isobornyllithium (22). The reactions were performed in pentane at - 80°C; in diethyl ether and THF the e.e.'s were only slightly higher, and at higher temperatures the selectivity was rapidly decreasing. It was shown that racemization takes place by an intermolecular transmetallation reaction. The structure of 29f [n = 3] was elucidated by an X-ray analysis.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911241120
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