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21.
McGrath JW Hammerschmidt F Kählig H Wuggenig F Lamprecht G Quinn JP 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(47):13341-13348
Racemic (1R*,2R*)‐1,2‐dihydroxy‐[1‐13C1]propylphosphonic acid and 1‐hydroxy‐[1‐13C1]acetone were synthesized and fed to R. huakuii PMY1. Alanine and a mixture of valine and methionine were isolated as their N‐acetyl derivatives from the cell hydrolysate by reversed‐phase HPLC and analyzed by NMR spectroscopy. It was found that the carbon atoms of the respective carboxyl groups were highly 13C‐labeled (up to 65 %). Hydroxyacetone is therefore considered an obligatory intermediate of the biodegradation of fosfomycin by R. huakuii PMY1. 相似文献
22.
William J. Rolli 《Journal of Mathematical Analysis and Applications》2006,321(1):388-395
In this paper, we use the characterization of frames, introduced in [W. Rolli, A characterization of frames for finite dimensional Hilbert spaces, preprint], to construct frames for finite dimensional Hilbert spaces. Furthermore this approach allows for the construction of frames with prescribed properties. 相似文献
23.
An algebra A over a field k is FCR if every finite dimensional representation of A is completely reducible and the intersection of the kernels of these representations is zero. We give a useful characterization
of FCR-algebras and apply this to C
*-algebras and to localizations. Moreover, we show that “small” products and sums of FCR-algebras are again FCR.
Received: 25 October 2000 相似文献
24.
Hanspeter Kraft 《Commentarii Mathematici Helvetici》1970,45(1):110-118
Ohne Zusammenfassung 相似文献
25.
Summary We study closures of conjugacy classes in the Lie algebras of the orthogonal and symplectic groups and determine which ones
are normal varieties. Furthermore we give a complete classification of the minimal singularities which arise in this context,
i.e. the singularities which occur in the open classes in the boundary of a given conjugacy class. In contrast to the results
for the general linear group ([KP1], [KP2]) there are classes with non normal closure; they are branched in a class of codimension
two and give rise to normal minimal singularities. The methods used are (classical) invariant theory and algebraic geometry.
Supported in part by the SFB Theoretische Mathematik, University of Bonn, and by the University of Hamburg 相似文献
26.
Hans Fritz Paul Hug Hanspeter Sauter Tammo Winkler Sven-Olov Lawesson Bjarne Skindhoj Pedersen Sten Scheibye 《Magnetic resonance in chemistry : MRC》1981,16(1):36-43
N,N-diisopropylamides and -thioamides show hindered rotation around the N? CH bonds, and the presence of mixtures of conformational isomers can be demonstrated at temperatures below 273 K in solution. 1H and 13C NMR spectra of these conformers are measured and assigned. The 13C data serve to study through-space effects on 13C chemical shifts, which strongly depend on the conformations of the isopropyl groups. For amides, a through-space shielding of the N-methine carbons is found to exist only for conformers in which the methine hydrogen atom is spatially close to the oxygen atom. Chemical shift differences between amides and thioamides can be rationalized in terms of through-bond and through-space contributions, and serve for a better understanding of the shift differences in N,N-dialkylamides and -thioamides. 相似文献
27.
28.
29.
Bieri Hanspeter 《Commentarii Mathematici Helvetici》1970,45(1):393-404
Ohne Zusammenfassung 相似文献
30.
Synthesis of Diterpenes as Possible Biogenetic Precursors of the C20-Carotenoid Crocetin With regard to the investigation of the biosynthesis of the C20-carotenoids in saffron the four diterpenes 6–9 were synthesized, who differ only in their degree of saturation. A detailed analysis of their 1H- and 13C-NMR spectra has been achieved by their mutual comparison. 相似文献