立体异构

Synthesis and Structure of 1-(m-Methoxyphenyl)-2- cyclohexanol

对反应的立体化学进行了分析，并用13CNMR谱确定了顺反异构体的构型。

In addition, NBO analysis shows that it is hyperconjugation rather than repulsive forces that plays a key role in the relative stabilities of isomers.

此外， 通过NBO方法分析了分子的超共轭作用和立体排斥能对异构体稳定性的影响，结果表明超共轭作用是影响各异构体构型相对稳定性的主要因素。

Use of stereoselective or stereospecific synthetic methods or separation of racemic mixtures can be used to obtain individual optical isomers.

可以使用立体选择或立体专一的合成方法，或者外消旋混合物的分离，来获得单独的光学异构体。

It is found that the stereochemistry of the reactions of telluronium allylide,crotonylide and trimethylsilyallylide with α,β-unsaturated esters and amides can be tuned by thechoice of reaction conditions.

利用反应条件的变化首次实现了烯丙基、巴豆基、含硅烯丙基碲叶立德与α，β-不饱和酯、酰胺进行环丙烷反应的立体化学调控，能高立体选择性地、高效率地合成两种不同几何异构体中的一个。

Respectively, glutamic acid derivatized β-CD has been synthesized with epoxy chloropropane as the intermediate, a water-insoluble yellow liquid was got after the acetylating of the by using acetic anhydride, which was used as a novel gas chromatographic CSP; A water-soluble β-CD polymer cross-linked with epoxy chloropropane has been synthesized, and the derivatives of β-CD polymer were synthesized by its alkylating and acetylating. The different β-CD derivatives were coated on silica capillary columns by dynamic method, the chromatographic properties and retention behaviors of the fused silica capillary columns were studied, the results showed that the β-CD derivatives had good stereoselectivity and separation results to some compounds, especially to various positional isomers and enantiomers.

本文还分别以环氧氯丙烷为中间体，合成了七{2，6-二-O-[3-(1，3-二羟基丙氨酸)]}-β-环糊精，再用醋酸酐将其乙酰化，得到了一种淡黄色粘稠液体，合成了一种新型的环糊精衍生物；以环氧氯丙烷作交联剂合成了一种水溶性的β-环糊精聚合物，再将其烷基化和酰基化，合成了β-环糊精聚合物的不同衍生物，用动态法将不同类型的β-环糊精衍生物涂渍在石英毛细管柱上，通过对所制备柱柱性能的测试和对一系列化合物的分离和保留行为的研究，结果表明所合成的β-环糊精衍生物对各类化合物，特别是对位置异构体和对映异构体具有较好的分离效果，显示了很强的立体选择性。

This requirement may be satisfied by the submission of information such as the following: name (generic name, chemical name, code number); Chemical Abstracts Service number if available; description (e.g., appearance, color, physical state); molecular formula and molecular weight; structural formula (including ionic state if applicable); stereochemistry identifying chiral centers, cis-trans isomerism, etc.

该要求可以通过提供下述信息来满足：名称（通用名、化学名、编码等）、化学摘要服务编码、性状描述（如：外观、颜色、物理状态）、分子式和分子重量、结构式、立体化学（找出手性中心、顺式反式异性等）、对映结构体比率（如：外消旋物、规定的异构体、对映异构物和固态形式的混合物）、溶解度概况、分配系数、溶液 pH 值、解离常数、熔点或沸点、折射率、比重。

This requirement may be satisfied by the submission of information such as the following: name (generic name, chemical name, code number ); Chemical Abstracts Service number if available; description (e.g., appearance, color, physical state ); molecular formula and molecular weight; structural formula (including ionic state if applicable ); stereochemistry identifying chiral centers, cis-trans isomerism, etc.

有的话、描述（如：外观、颜色、物理状态）、分子式和分子重量、结构式、立体化学（找出手性中心、顺式贯穿异性等）、对映结构体或固态形式比率（如：外消旋物、规定的异构体、对映异构物和固态形式的混合物）、溶解性档案、分隔系数、溶液pH值、解离常数、熔点和沸点、拆射率、精确重力。

Many studies dealing with chiral drugs which are administered as their racemates rely on non-stereoselective analytical techniques. It was shown that the use of such an analytical method can lead to the collection of data which may be both quantitatively and qualitatively inaccurate with respect to the individual enantiomers.

一般非对掌选择性的药物分析条件，得到的药物血中浓度是个别镜像异构物的总和，而非个别镜像异构物的血中浓度，因此并无法对於对掌性药品的立体选择性动态学做定性或定量的探讨。

Enantiomer or solid-state form ratios (e.g., for racemates, and for defined admixtures of isomers or enantiomers or solid-state forms); solubility profile (aqueous and nonaqueous as applicable); partition coefficients; solution pH; dissociation constant; melting or boiling point; refractive index; specific gravity.

该要求可以通过提供下述信息来满足：名称（通用名、化学名、编码等）、化学摘要服务编码、性状描述（如：外观、颜色、物理状态）、分子式和分子重量、结构式、立体化学（找出手性中心、顺式反式异性等）、对映结构体比率（如：外消旋物、规定的异构体、对映异构物和固态形式的混合物）、溶解度概况、分配系数、溶液pH值、解离常数、熔点或沸点、折射率、比重。

Enantiomer or solid-state form ratios (e.g., for racemates, and for defined admixtures of isomers or enantiomers or solid-state forms); solubility profile (aqueous and nonaqueous as applicable); partition coefficients; solution pH; dissociation constant; melting or boiling point; refractie index; specific graity.

该要求可以通过提供下述信息来满足：名称（通用名、化学名、编码等）、化学摘要服务编码、性状描述（如：外观、颜色、物理状态）、分子式和分子重量、结构式、立体化学（找出手性中心、顺式反式异性等）、对映结构体比率（如：外消旋物、规定的异构体、对映异构物和固态形式的混合物）、溶解度概况、分配系数、溶液pH值、解离常数、熔点或沸点、折射率、比重。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。