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991.
David G. Churchill Jun Ho Shin Gerard Parkin 《Journal of chemical crystallography》2003,33(4):297-302
Photolysis of (CpBu
t)2MoH2 in benzene yields the molybdenocene derivative trans-[(CpBu
t)Mo(- ,5-C5H3But)H]2. An X-ray diffraction study demonstrate that the molybdenum centers of trans-[(CpBu
t)Mo(- , 5-C5H3But)H]2 are bridged by two , 5-C5H3But ligands, each one of which coordinates in a -manner to one molybdenum center and an 5-manner to the other, thereby resulting in a centrosymmetric dimer with a structural type that is different from that of [CpMo(- , 5-C5H4)]2 which possesses a Mo–Mo bond. 相似文献
992.
Polymethoxyflavones (PMFs), which exist exclusively in the citrus genus, have biological activities including anti-inflammatory, anticarcinogenic, and antiatherogenic properties. A validated RPLC method was developed for quantitative analysis of six major PMFs, namely nobiletin, tangeretin, sinensetin, 5,6,7,4'-tetramethoxyflavone, 3,5,6,7,3',4'-hexamethoxyflavone, and 3,5,6,7,8,3',4'-heptamethoxyflavone. The polar embedded LC stationary phase was able to fully resolve the six analogues. The developed method was fully validated in terms of linearity, accuracy, precision, sensitivity, and system suitability. The LOD of the method was calculated as 0.15 microg/mL and the recovery rate was between 97.0 and 105.1%. This analytical method was successfully applied to quantify the individual PMFs in four commercially available citrus peel extracts (CPEs). Each extract shows significant difference in the PMF composition and concentration. This method may provide a simple, rapid, and reliable tool to help reveal the correlation between the bioactivity of the PMF extracts and the individual PMF content. 相似文献
993.
This study examines the supercritical carbon dioxide (SC-CO(2)) extraction of oryzanols contained rice bran oil from powdered rice bran. The extraction efficiencies and concentration factors of oryzanols, free fatty acids and triglycerides in the SC-CO(2) extracts were determined. With top-flow type SC-CO(2) extraction the total oil yield was 18.1% and the extraction efficiencies of oryzanols and triglycerides were 88.5 and 91.3% respectively, when 2750 g CO(2 )was consumed during the extraction of 35 g rice bran powder. The concentration factors of oryzanols and triglycerides in SC-CO(2)-extracted oil were higher than in the Soxhlet n-hexane extracted oil. SC-CO(2) extractions indicated that pressure can be used more effectively than temperature to enhance the extraction efficiency and concentration factor of oryzanols. A two-factor central composite scheme of response surface methodology was employed to determine the optimal pressure (300 bar) and temperature (313 K) for increasing the concentration of oryzanols in the SC-CO(2) extracted oil. 相似文献
994.
A reliable multiplex assay procedure to detect human genetic mutations in the breast cancer susceptibility gene BRCA1 using zip-code microarrays and single base extension (SBE) reactions is described. Multiplex PCR amplification was performed
to amplify the genomic regions containing the mutation sites. The PCR products were then employed as templates in subsequent
multiplex SBE reactions using bifunctional primers carrying a unique complementary zip sequence in addition to a mutation-site-specific
sequence. The SBE primers, terminating one base before their mutation sites, were extended by a single base at a mutation
site with a corresponding biotin-labeled ddNTP. Hybridization of the SBE products to zip-code microarrays was followed by
staining with streptavidin–Cy3, leading to successful genotyping of several selected BRCA1 mutation sites with wild-type and heterozygote mutant samples from breast cancer patients. This work has led to the development
of a reliable DNA microarray-based system for the diagnosis of human genetic mutations.
Cheulhee Jung and Seong-Chun Yim contributed equally to this work. 相似文献
995.
Jin Ho Kwak 《Discrete Mathematics》2008,308(11):2156-2166
In this paper, we classify the reflexible regular orientable embeddings and the self-Petrie dual regular orientable embeddings of complete bipartite graphs. The classification shows that for any natural number n, say (p1,p2,…,pk are distinct odd primes and ai>0 for each i?1), there are t distinct reflexible regular embeddings of the complete bipartite graph Kn,n up to isomorphism, where t=1 if a=0, t=2k if a=1, t=2k+1 if a=2, and t=3·2k+1 if a?3. And, there are s distinct self-Petrie dual regular embeddings of Kn,n up to isomorphism, where s=1 if a=0, s=2k if a=1, s=2k+1 if a=2, and s=2k+2 if a?3. 相似文献
996.
Wing Kai Ho 《Israel Journal of Mathematics》2008,168(1):189-200
We will show that for any positive integer k, there exists a smooth manifold that has no -geodesic. 相似文献
997.
Rho HS Oh SH Lee JW Lee JY Chin J Song CE 《Chemical communications (Cambridge, England)》2008,(10):1208-1210
Highly enantioselective methanolysis of meso-cyclic anhydride was achieved with bifunctional organocatalyst containing a quinine-thiourea moiety; unusual concentration, temperature and solvent effects on the enantioselectivity can be explained in terms of a mechanism involving monomer-dimer equilibration of the catalyst. 相似文献
998.
Choi HC Lee S Lee KK Noda I Park C Kwon CH Jung YM 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(4):1110-1113
A promising possibility for the quantitative analysis of X-ray absorption near edge structure (XANES) spectra of nanosized electrode materials is demonstrated. We used a 2D map representation technique, which utilizes the values of the first derivatives of the absorbance with respect to the inserted Li(+) content plotted over the two-dimensional space defined by the inserted Li(+) content (mole) versus photon energy (eV) as a single map. The technique was applied to XANES spectra of the Li(y)CoO system in the first Li(+) insertion reaction for determining the structural and electronic variations associated with the change in Li(+) content. The obtained show that the intensities of two peaks at 7725 and 7711 eV increased with the Li(+) content and the difference of intensity change of these two peaks carried out for successive couples of spectra yielded the largest changes at 1.05 and 1.98 mol of Li content. This approach for quantitative analysis of XANES without using conventional simulation techniques enable us to interpret X-ray absorption spectroscopy (XAS) as a quantitative analytical technique with greater confidence. 相似文献
999.
1000.