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31.
Every finitely presented MV-algebra A has a unique idempotent valuation E assigning value 1 to every basic element of A. For each a ∈ A, E(a) turns out to coincide with the Euler characteristic of the open set of maximal ideals m of A such that a/m is nonzero. 相似文献
32.
Three different staining techniques were compared for the detection of nonhistone high mobility group (HMG) proteins after acidic urea-polyacrylamide gel electrophoresis. Silver staining after glutaraldehyde fixation provides the highest detection sensitivity. Because of the acid solubility of HMG proteins special care has to be taken concerning fixation. Staining with colloidal CBB G-250 according to Neuhoff et al. is superior in sensitivity and reliability of quantitation when compared with noncolloidal Coomassie Brilliant Blue R-250. High detection sensitivity and reproducibility of quantitation are prerequisites for studying the tissue-specific expression of HMG proteins. In the present study tissue-specific differences in the molar amounts of various HMG proteins in thymus and erythrocytes of the chicken are documented by application of the methods tested. 相似文献
33.
We present a method by which the phase and the amplitude of a wave front are obtained by processing a sequence of intensity patterns recorded at different planes. We do not use any reference wave, as one does for holography. Simulations and experimental results are presented. 相似文献
34.
We describe a method where the wavefront emitted by a self-luminous object is superimposed to its filtered counterpart by using a Mach-Zehnder interferometer. The amplitude and phase of the resulting interference pattern is used for digital three-dimensional imaging. Experimental results are presented. 相似文献
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Giovannini PP Fantin G Massi A Venturi V Pedrini P 《Organic & biomolecular chemistry》2011,9(23):8038-8045
An enzymatic strategy for the preparation of optically pure α-alkyl-α,β-dihydroxyketones is reported. Homo- and cross-coupling reactions of α-diketones catalyzed by acetylacetoin synthase (AAS) produce a set of α-alkyl-α-hydroxy-β-diketones (30-60%, ee 67-90%), which in turn are reduced regio-, diastereo-, and enantioselectively to the corresponding chiral α-alkyl-α,β-dihydroxyketones (60-70%, ee >95%) using acetylacetoin reductase (AAR) as catalyst. Both enzymes are obtained from Bacillus licheniformis and used in a crude form. The relative syn stereochemistry of the enantiopure α,β-dihydroxy products is assigned by NOE experiments, whereas their absolute configuration is determined by conversion of the selected 3,4-dihydroxy-3-methyl-pentan-2-one to the natural product (+)-citreodiol. 相似文献
37.
Stefania Costa Pier Paolo Giovannini Giancarlo Fantin Alessandro Medici Paola Pedrini 《Helvetica chimica acta》2013,96(11):2124-2133
The biotransformations of cholic, deoxycholic, and hyocholic acids with Rhodococcus ruber are reported. In all biotransformations, the C17‐side chain is partially degraded, and the new 9,10‐secosteroids 4a (54%) and 4b (55%) are obtained from cholic and deoxycholic acids, respectively. The loss of H2O from C(11)? C(12) of secosteroids 4a and 4b affords the compounds 5a (5%) and 5b (20%), respectively. On the other hand, in the biotransformation of hyocholic acid with R. ruber the 9,10‐secosteroid 4c is not detected, but, rearranging to an intramolecular hemiacetal form, it evolves to the final furan derivative 6c (35%) by easy elimination of two molecules of H2O. The new secosteroids were characterized by IR, NMR, and 2D‐NMR spectroscopy, and mass spectroscopy. 相似文献
38.
Deoxygenation of Pyridine N-oxides with sulphur monoxide generated from -2,3-diphenylthiiran-1-oxide
Bianca F. Bonini Gaetano Maccagnani Germana Mazzanti Paola Pedrini 《Tetrahedron letters》1979,20(20):1799-1800
Pyridine N-oxides are deoxygenated by sulphur monoxide. Electron withdrawing substituents lower drastically the yields of reduction. 相似文献
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