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991.
用^3HNMR波谱法分析微波激发催化交换制备的^3H标记颠茄类生物碱 总被引:1,自引:0,他引:1
用~3H NMR波谱法测定了微波激发催化交换制备的四种~3H标记颠茄类生物碱示踪剂的氚标记位置及其相对百分含量。并在用~1H NMK归属原料纯度及标记物分子各基因化学位移时采用了水峰抑制技术(简称WEFT),既能同时消除溶剂氘代甲醇及水峰的影响;又能提高灵敏度(近10倍),从而计算出所得标记产物的化学纯度值与放化纯度值。为快速、准确寻找制备标记生物碱的最佳实验条件和控制标记物质量提供了唯一的物理无损分析方法。 相似文献
992.
993.
A simple and sensitive kinetic method was developed for the determination of ritodrine hydrochloride in pharmaceutical preparations. The method is based upon a kinetic investigation of the oxidation reaction of the drug with alkaline potassium permenganate at room temperature for a fixed 12.5 min; the absorbance of the colored permenganate ion was measured at 609 nm. The absorbance concentration plots were rectilinear over the range of 1.6–11.2 μg mL?1 (r = 0.9992) with a minimum detectability of 0.096 μgmL?1 (2.88 × 10?7 M). The different experimental parameters affecting the development and stability of color were carefully studied and optimized. The determination of ritodrine hydrochloride by the fixed concentration and rate constant methods is also feasible with the calibration equations obtained, but the fixed time method has been found to be more applicable. The proposed method was applied successfully to the determination of ritodrine hydrochloride in tablets and ampoules with average recoveries of 100.37 ± 0.93% and 100.42 ± 0.87%, respectively. The results obtained were in good agreement with those obtained using a reference method for comparison. A proposal of the reaction pathway is also presented. 相似文献
994.
Xiao Hong YAN Yue Wei GUO* State Key Laboratory of Drug Research Institute of Materia Medica Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Shanghai 《中国化学快报》2005,16(3)
Marine organisms have been found to be a storehouse of steroids, particularly in term ofunique side-chain structures and unusual functionalization. Marine steroids are oftenfound in highly oxygenated forms and possessing various biological activities1.Previously, we reported the isolation and structural elucidation of three new marinesteroids, nanjiols A-C, which showed cytotoxicity against HL-60 and BEL 7402 celllines, from a soft coral Nephthea bayeri in East China Sea2. In continuation … 相似文献
995.
Xiao Ying Xu Feng Cheng Jian Hua Shen Xiao Min Luo Li Li Chen Li Duo Yue Yi Du Fei Ye Shan Hao Jiang Da Yuan Zhu Hua Liang Jiang Kai Xian Chen 《International journal of quantum chemistry》2003,93(6):405-410
Docking simulation of 18 agonists with the ligand binding pocket (LBP) of PPARγ has been performed. The binding conformations and binding affinities of these agonists were obtained by use of the flexible docking protocol FlexX. Test compound calculations indicated that FlexX can reproduce the binding conformation of the crystal structure (root mean square deviation = 1.43 Å); moreover, the predicted binding affinities correlate well with the activities of these agonists. The interaction model and pharmacophore of PPARγ agonists were derived and the difference in biologic activities of these agonists can be well explained. The PPARγ agonists must have both polar head and the hydrophobic tail, which form hydrogen bonds and hydrophobic contacts with hydrophilic and hydrophobic regions of the LBP of PPARγ, respectively. In addition, a suitable linker is also necessary. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 405–410, 2003 相似文献
996.
997.
Yi‐Hang Wen Xia Feng Yin‐Hua He You‐Zhao Lan Hong Sun 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(11):m504-m506
In the title complex, [Zn(C12H6O4)(H2O)]n, a ZnII polymer based on naphthalene‐1,8‐dicarboxylate (1,8‐nap), the ZnII atoms adopt an elongated octahedral coordination geometry. A zigzag chain is formed by μ2‐aqua ligands and μ2‐carboxylate groups of the 1,8‐nap ligands. Adjacent parallel chains are further linked by 1,8‐nap ligands, forming a twisted two‐dimensional layer structure along the (100) plane. 相似文献
998.
Sergio M. Bonesi Maria A. Ponce Rosa Erra‐Balsells 《Journal of heterocyclic chemistry》2004,41(2):161-171
1H and 13C nmr spectra of several N‐ and C‐substituted carbazoles (Series 1, 2, 3 and 4) were measured. Correlations between chemical shifts and substituent constants show that these parameters describe properly the substituent effect on the nmr phenomena. Atomic charge densities for carbazoles of Series 1, 2, 3 and 4 were calculated by using the semi empirical PM3 method. These values also show a linear correlation with the 13C chemical shifts. The synthesis of several carbazole derivatives 1a – 1g, 2a – 2g, 3a – 3j and 4a – 4g have been carried out according to literature procedures. The carbazoles 3i, 3j and 4c have been synthesized and fully characterized for the first time. 相似文献
999.
十二烷基季铵盐及其与十二烷基硫酸钠混合体系的表面活性 总被引:13,自引:0,他引:13
通过表面张力测定,研究了十二烷基季铵盐C12H25N(CnH2n+1)3Br(n=1,2,3,4)及其与十二烷基硫酸钠混合体系的表面活性,应用规则溶液理论,计算了混合体系表面吸附层和胶团的组成及分子相互作用参数,对于季铵盐、极性基影响大:cmc随n增加而下降,γcmc则先上升,后下降,自极性基碳链的空间阻碍、疏水、弯曲效应,以及电荷屏蔽效应可对此予以解释,对于混合体系,极性基大小对其表面活性及胶团 相似文献
1000.
富镉Hg_(1-x)Cd_xTe是一种新型的光电转换材料,已用于固体结太阳能光伏电池:ITO/CdS/Hg_(1-)Cd_xTe/Au。我们曾对Hg_(1-x)Cd_xTe的电沉积机理作过研究。最近我们用电沉积制备的Hg_(0.09)Cd_(0.91)Te多晶薄膜做成了液体结太阳能光电化学电池并观察到明显光电响应。 相似文献