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991.
The perchlorovinylcarbene adducts of ethylene and propylene served as precursors toa wide spectrum of 1’-substituted cycllorpropylacetylenes 4, 8 and 9, which are versatile polyfunctional molecules. E.g., the acetylenic ester 4c underwent cycloaddition to1,3-dienes giving otherwise unaccessible compounds. 相似文献
992.
993.
MNDO and MINDO/3 calculations were used to study the photochemical formation, thermal rearrangements, and dissociation of bicyclo[2.1.0]pentenone. The “forbidden” thermal conversion to cyclopentadienone requires little activation, which accounts for the low kinetic stability of bicyclo[2.1.0]pentenone. The theoretical results seem to be compatible with the available experimental evidence for the tri-tert-butyl-substituted systems and suggest an explanation for observed differences in reactivity. 相似文献
994.
995.
Peter Welzel Hans-Peter Bullan Armin Maulshagen Dietrich Mu´ller Gu¨nther Snatzke 《Tetrahedron》1984,40(19):3657-3666
The absolute configuration of the moenuronic acid moiety of the antibiotic moenomycin A has been established by a partial synthesis starting from D-galactose. The relation between the absolute conformation of α-hydroxy lactones and their chiroptical properties is discussed in detail. 相似文献
996.
997.
Armin Petzold 《Analytical and bioanalytical chemistry》1956,149(4):258-263
998.
Armin N. Aufdermaur Roland List William C. Mayes Marcel R. de Quervain 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1963,14(5):574-589
Summary The big single crystals of a shell of a hailstone are mostly arranged in palisades, directed to a certain point. This preferred orientation of shape of single crystals is identical to the direction of growth of the hailstone at the place of the crystallite refered to. If we look at the statistical deviation of the direction of thec-axis — determined by a Replica method — of the crystallites of a whole shell from the local direction of growth, we find that thec-axis looks mainly in the direction of growth (Figures 7, 10, 12) but the relative height of the maximum of the distribution may vary from one shell to another (Figures 7 and 10). Although in one case no rule of orientation could be found (Figures 14 and 15) and in another thec-axis was perpendicular to the direction of growth (Figure 16). Results of some primary investigations, based upon experiments in the hail tunnel, leed us to the conclusion that the arrangement of the crystallographic axis of the different single crystals depends very much on the growing conditions of the ice deposits. Therefore one may expect, that in the near future an interpretation of the icing conditions of natural hailstones is possible on behalf of their crystallographic structure. Icing experiments in the hail tunnels will give us the rules one has to observe for this procedure. 相似文献
999.
1000.
Armin Leutbecher 《Archiv der Mathematik》1972,23(1):151-153
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