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991.
A nonaqueous capillary electrophoresis (NACE) method was developed for simultaneous assay of three bioactive components (1: cryptotanshinone; 2: tanshinone IIA, and 3: tanshinone I) in Radix Salviae miltiorrhizae and in its herbal preparations for the first time. After optimization of separation conditions, a buffer of 250 mmol L(-1) ammonium acetate containing 30% acetonitrile and 1.0% acetic acid (V:V) in methanol was selected for separating the three analytes, but baseline separation of tanshinon I and tanshinone IIA was not obtained. Therefore second-order derivative electropherograms were applied for resolving overlapping peaks. Regression equations revealed good linear relationships (correlation coefficients 0.9943-0.9991) between peak heights in second-order derivative electropherograms and concentrations of the three analytes. The relative standard deviations (RSD) of the migration times and the peak height of the three constituents were in the range of 0.81 -0.88% and 0.34-1.13% (intra-day), 1.57-1.86% and 3.05-5.52% (inter-day), respectively. The recoveries of three constituents ranged from 90.2 to 108.5%. The results indicated that baseline separation of the analytes was sometimes hard to obtain and second-order derivative electropherograms were applicable for the resolving and analysis of overlapping peaks. 相似文献
992.
由Philips引进的PW1700X射线衍射仪织构测量系统只能用反射法,按螺旋线扫测极目数据,测绘极角。α≤85°的不完整极图。经功能开发后,建立了织构分析测算系统,织构分析应用软件包,包括不完整极图测量与ODF(取向分布函数)计算,回算全极图与反极图,可彩色屏显考贝,并能进行织构的定量分析。适用于立方和六方品系多晶织构材料分析。近两年应用表明,软件功能优异。 相似文献
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采用紫外光电子能谱(PES)和量子化学方法,研究了以CFCl3化合物为代表的系列化合物(CFCl3、CF2Cl2、CF3Cl、CCl4)不同离子态的电子结构和性质。结果表明,四种化合物CF3Cl、CF2Cl2、CFCl3、CCl4的第一电离能依次下降。结合从头算自洽场分子轨道(abinitioSCFMO)和外壳层格林函数法(OVGF)计算对化合物的PES进行了分析和指认,表明化合物的外层轨道中Cl的孤对电子成分对电离能存在明显的影响;外层格林函数法计算得到电离能与实验吻合很好;同时发现在外壳层格林函数法计算结果中由于考虑相关能,得到的分子轨道存在能级顺序的交错。 相似文献
996.
The study of the emulsification efficiency of Aerosil and HPMCAS type and their ratio to stabilize emulsions of zedoary turmeric oil 总被引:1,自引:0,他引:1
Jian You Fu-de Cui Yong-sheng Wang Ying-wei Yu Xin Li Qing-po Li 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,280(1-3):76-80
The solid particles or polymers were often solely used to stabilizing emulsions, as an interesting alternative to classical used emulsifiers. However, a united use of them and the relation between them at stabilizing emulsions were little reported. Our previous study showed that the preparation of microspheres containing zedoary turmeric oil (ZTO, as an oily drug), Aerosil200 particles and hydroxypropyl methylcellulose acetate succinate (HPMCAS). ZTO emulsions were produced when the microspheres were immersed into aqueous media and disaggregated under gentle agitation, and were stabilized by Aerosil200 particles and HPMCAS. Nevertheless, more work needs to be carried out to explain the factor affecting emulsification efficiency of microspheres, which will facilitate the design of the microsphere formulation. Thus, in this study, we dealt with a system consisting of Aerosil, HPMCAS, ZTO and water. To predict the best ratio of Aerosil/polymer and thus obtain the best satisfying ZTO emulsions, the bonding studies were carried out with Aerosil and HPMCAS. A series of emulsions was prepared and the stability and droplet size of resultant emulsions were investigated. The results indicated two kinds of HPMCAS (HPMCAS-LG and -HG) showed the different affinity for Aerosil200, which resulted in the unlike capability to stabilize emulsions when at the same Aerosil/polymer ratio. The stability and droplet size of emulsions increased on increasing the ratio Aerosil to polymer, and the best ratio was predictable from the Langumuir-fit of the adsorption isotherms. Appropriate hydrophilicity and hydrophobicity with Aerosil particles were very important to stabilizing the ZTO emulsions. 相似文献
997.
Detlef Heller Jens Holz Igor Komarov Hans-Joachim Drexler Jingsong You Karheinz Drauz Armin Brner 《Tetrahedron: Asymmetry》2002,13(24):2735-2741
The rhodium(I)-catalyzed enantioselective hydrogenation of E- and Z-configured β-acylamido β-alkylacrylates as well as of isomeric mixtures has been investigated. As ligands 1,2-bisphospholanes like DuPHOS, BPE and Me4-BASPHOS have been tested, but also diphosphines forming seven-membered chelates such as DIOP. The effect of additional oxy groups in the diphosphine ligand on rate and enantioselectivity was likewise elucidated. In general, with all catalysts screened the hydrogenation is strongly sensitive to the E/Z-geometry of the substrate. E-Substrates are converted with good or excellent enantioselectivites into the desired β-amino acid derivatives. The hydrogenation of Z-substrates showed the known H2-pressure dependency of the ee. 相似文献
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