异构体

Objective To develop an RP-HPLC for simultaneous determination of the epimers of glycyrrhizic acid in Radix Glycyrrhizae.

目的 建立RP-HPLC法同时测定甘草药材中甘草酸差向异构体的含量。

Under building a optimal HPLC condition,the epimers can be seperated well and can be studied by MS,LC-MS and NMR.

双氢青蒿素在有机溶媒中存在α与β差向异构体的转化过程。

These include catechin and gallocatechin (hydroxyls at positions 5' as well as at 3' and 4' as in catechin), their esters with gallic acid, catechin gallate, and gallocatechin gallate, and their epimers.

它们有几茶素和儿茶素(在5'位上以及如同儿茶素中一样在3'和4'位上羟基化)，它们与酸生成的酯，即儿茶素酸酯和儿茶素酸酯，以及它们的差向异构体。

Sitafloxacin epimers were separated by capillary zone electrophoresis using γ-cyclodextrin and D-phenylalanine as chiral selector.

以γ-环糊精和D-苯丙氨酸为手性选择剂，采用毛细管区带电泳成功地分离了新型抗菌素西他沙星差向异构体。

Its main active component is glycyrrhizic acid. GL hastwo epimers, namelyα-GL andβ-GL.

甘草酸具有两种差向异构体，分别为α-GL和β-GL。

A baseline separation of Sitafloxacin epimers was achieved with a background electrolyte of 10 mmol/L KH2PO4-K2HPO4 (pH 4.5), 10 mmol/L CuSO4, 20 mmol/L γ-CD and 10 mmol/L D-Phe. The linear range for Sitafloxacin was 32-400 mg/L (0.996). The relative standard deviations of migration time and peak area were less than 1.9% and 3.8% respectively.

实验结果表明，添加剂的种类和浓度是影响西他沙星手性分离的重要因素，只有当D-苯丙氨酸、铜离子和γ-环糊精同时存在并达到一定浓度时，西他沙星差向异构体在毛细管电泳中才具有良好的分离效果。

Two approaches for the asymmetric syntheses of naturally occuring eudesmane-type triol kudtriol and 5-epi-kudtriol as well as their C-11 epimers were achieved starting from-dihydrocarvone through six and seven steps, respectively.

以-二氢香芹酮为原料，用两条合成路线分别经六、七步反应完成了三羟基桉烷类天然产物Kudtriol、5-epi-Kudtriol及它们的C-11位差向异构体的不对称全合成。

High performance liquid chromatography, carbon-13 nuclea magnetic resonance, chemical ionization mass spectrometry and gas chromatography with flame ionization detection have been employed for the identification and quantitative deter mlnation of the epimers of amygdalin.

登录后回答可以获得经验值奖励，并可以查看和管理所有的回答。登录|高效液相色谱法、carbon-13 nuclea 磁场共振电离质谱、化学品与气相层析法，以氢火焰离子化检测被用来识别和定量的威慑 mlnation差向异构体的苦的。

This Sm-catalyzed reaction firstly efficiently realized the catalytic cycle in the tandem rearrangement/reduction reaction of α-hydroxy epoxides, and moreover the diastereoselective amplification could be distinctly observed when two C1 epimers in substrate were subjected to this catalytic tandem reaction.

该催化的多功能串联反应，高度非对映选择性地一步控制了含有季碳的三个相邻立体中心，有效地构建了&2-季碳1，3-二醇&结构单元，首次实现了此类重排—还原过程的催化循环，其中对于两个C1位的差向异构体底物，此反应具有明显的非对映选择性放大特点。

The number of optical isomers is 2n, where n is the number of asymmetric centers.

光学异构体的数量是2 n，在此n是不对称中心的数量。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。