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1.
The total synthesis of an alkylcitrate secondary metabolite from the fungi Trichoderma viride is described. An ester dienolate [2,3]-Wittig rearrangement and a S. Julia-Kocienski olefination served as key C/C-connecting transformations. The highly convergent synthesis consists of a longest linear sequence of 17 steps. 相似文献
2.
Simplicial complexes X provide commutative rings A(X) via the Stanley- Reisner construction. We calculated the cotangent cohomology, i.e., T1 and T2 of A(X) in terms of X. These modules provide information about the deformation theory of the algebro geometric objects assigned to X. 相似文献
3.
Klaus Altmann 《Semigroup Forum》1996,53(1):89-97
We introduce an invariant for semigroups with cancellation property. When the semigroup equals the set of lattice points in
a rational, polyhedral cone, then this invariant describes the torsion of the differential sheaf on the associated toric variety.
Finally, as an example, we present the case of two-dimensional cones (corresponding to two-dimensional cyclic quotient singularities). 相似文献
4.
5.
F. Kulcsár D. Teherani H. Altmann 《Journal of Radioanalytical and Nuclear Chemistry》1982,68(1-2):161-168
It is pessible to study experimentally Cherenkov light spectra in a liquid scintillation spectrometer with colour filters.
Cherenkov light spectra of60Co,198Au,115Cd,143Ce,140La,32P,86Rb,76As,42K and an external standard were studied in a Packard 3375 type liquid scintillation spectrometer, using 11 various Kodak Wratten
filters. The absorption maxima of the filters ware in the 410–796 nm interval. 相似文献
6.
7.
Angle-resolved bremsstrahlung isochromat spectra of the Ag(100), Ag(110) and Ag(111) surfaces have been measured. Our work extends and complements several earlier investigations of other authors. The data are summarized in the form of final state dispersionsE(k
). Comparison is made to the available theoretical and experimental information. The results for the bulk as well as for the surface-specific features are in excellent to reasonable agreement among each others and with recent calculations. 相似文献
8.
P. A. Sullivan J. Axelsson S. Altmann A. P. Quist B. U. R. Sunqvist C. T. Reimann 《Journal of the American Society for Mass Spectrometry》1996,7(4):329-341
Indirect information on the conformation of highly charged molecular ions may be obtained by monitoring their collisional cross sections and the course of simple gas-phase reactions such as hydrogen-deuterium exchange. In this work, another indirect but more visually oriented approach is explored: electrosprayed protein ions are accelerated toward a highly oriented pyrolytic graphite surface and the resulting single-ion defects are imaged by scanning force and tunneling microscopy. All protein impacts generated shallow hillocks: the shapes depended on the identity and charge state of the incident protein. Lysozyme and myoglobin, both compact, globular proteins in the native state, produced compact, almost circular hillocks. However, hillocks generated by myoglobin that had been denatured in the solution phase were elongated, and the elongation was positively correlated with the charge state of the ion. It appears that structural information about gas-phase multiply charged proteins can be derived from imprints generated by energetic protein impacts on surfaces. 相似文献
9.
The energy profiles for the decomposition of the first triplet of acetaldehyde via the reactions: CH3CHOν → CH3CO° + H°, CH3CHO* → CH.3 + HCO., have been computed using a non-empirical LCAO MO SCF procedure. Both reactions were found to have energy barriers of similar height (245 KJ mole ?1) and at similar extensions of the respective rupturing bonds (0.71–0.76 Å). The energy profile for internal rotation about the C-C bond was also calculated and showed a small barrier (3.5 kJ mole?1). 相似文献
10.
Zusammenfassung Das Überleben der Hefezellen nach - und -Bestrahlung wurde durch das Koloniebildungsvermögen ermittelt; bei gleicher Dosis und Dosisleistung wurden nur schwach unterschiedliche Effekte festgestellt. Das Nucleotidverteilungsmuster zeigte nach -Bestrahlung mit 300 000 rad größere quantitative Änderungen als nach -Bestrahlung. Die Konzentrationen an Nucleosidtriphosphaten war nach -Bestrahlung stärker herabgesetzt.Mit 5 AbbildungenLeiter: Prof. Dr.K. Kaindl. 相似文献