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41.
A GPI-anchored dipeptide of sperm CD52 antigen was prepared through a convergent synthesis. First, the dipeptide with its C-terminus free and the GPI with its nonreducing end phosphoethanolamine bearing a free amino group were synthesized separately. Then, the two building blocks were coupled with use of EDC/HOBt as the condensation reagent. Finally, the GPI-anchored peptide was deprotected to give the target molecule 1. 相似文献
42.
ShaoNongCHEN ShaoYuanCHEN HanDongSUN WenZhongLIN YaoZuCHEN 《中国化学快报》2004,15(5):539-542
Two novel ent-kauranoids with new sub-skeleton types, gesneroidins G and H were isolated as white powder from the ether extract of the leaves of Isodon gesneroides through normal phase column chromatography. Their structures were elucidated as 3β,6α,7β-triacetoxyl-15-hydroxyl-14-oxo-ent- 15,16-seco-kaur-11,17-olide and Iα-hydroxyl-3β,6α,7β,11 β-tetraacetoxyl-ent-nor-15,17-kaur-8,16-olide on the basis of the spectral evidences including ID and 2D NMR spectra. 相似文献
43.
Solvent effects on the electrochemistry and spectroscopic properties of alkyl- and aryl-substituted corroles in nonaqueous media are reported. The oxidation and reduction of six compounds containing zero to seven phenyl or substituted phenyl groups on the macrocycle were studied in four different nonaqueous solvents (CH(2)Cl(2), PhCN, THF, and pyridine) containing 0.1 M tetra-n-butylammonium perchlorate. Dimers were formed upon oxidation of all corroles in CH(2)Cl(2), but this was not the case in the other three solvents, where either monomers or dimers were formed upon oxidation depending upon the solvent Gutmann donor number and the number or location of aryl substituents on the macrocycle. The half-wave potentials were analyzed as a function of the number of aryl substituents on the macrocycle as well as the concentration of added pyridine to PhCN solutions of the compound, and these data were combined with data from the spectroelectrochemistry experiments to determine the stoichiometry of the species actually in solution after the first oxidation or first reduction of each compound. The results of these experiments indicate that reduction of the bispyridine adduct (Cor)Co(III)(py)(2) proceeds via the monopyridine complex (Cor)Co(III)(py) to give in each case the unligated cobalt(II) corrole [(Cor)Co(II)](-). In contrast, pyridine remains coordinated after electrooxidation, and the final product was characterized as [(Cor)Co(III)(py)(2)](+). 相似文献
44.
用具有流通池的分光光度计作测定装置,建立了由平衡移动法测定络合反应中质子释放数的新方法。方法简单、快速,仅用一个标准溶液,适于在变更pH值范围内金属离子不发生水解和没有其他副反应的体系。 相似文献
45.
46.
We derive the exact Bahadur slopes of studentized score tests for a simple null hypothesis in a one-parameter family of distributions. The Student's t-test is included as a special case for which a recent result of Rukhin (1993, Sankhy Ser. A, 55, 159–163) was improved upon. It is shown that locally optimal Bahadur efficiency for one-sample location models with a known or estimated scale parameter is attained within the class of studentized score tests. The studentized test has an asymptotic null distribution free of the scale parameter, and the optimality of likelihood scores does not depend on the existence of a moment generating function. We also consider the influence function and breakdown point of such tests as part of our robustness investigation. The influence of any studentized score test is bounded from above, indicating certain degree of robustness of validity, but a bounded score function is needed to cap the influence from below and to ensure a high power breakdown point. We find that the standard Huber-type score tests are not only locally minimax in Bahadur efficiency, but also very competitive in global efficiency at a variety of location models. 相似文献
47.
A novel molecular probe for identifying properties of supported transitionmetals and metal oxides catalysts was established.The catalytic mechanism oftransition metals was proposed. 相似文献
48.
本文合成了一些季铵盐聚合物试剂,研究了这些试剂对三氯乙酸分解生成三氯乙酰氯的催化作用。不同季铵盐聚合物催化剂对三氯乙酸分解的催化活性顺序如下: (?) (?) 聚合物催化剂经重复使用后,活性并无明显降低。 相似文献
49.
50.
Feng LIN Shao Yong BAI 《中国化学快报》2005,16(9):1158-1160
1, 3-Dimethyluracil (DMU) in phosphate buffered-saline (PBS, pH=8) was irradiated by a medium pressure mercury lamp (MPML) and produced a novel compound C6H9N2O6P. The composition and structure of the compound has been identified by elemental analysis, EIMS, UV, IR, ^1H and ^31P-NMR. 相似文献