立体异构

For lactic acid has one asymmetric carbon atom, the mechanical, physical and biological properties of PLA are related to the stereochemistry of lactic acids.

合成聚乳酸的初始物质―乳酸是有手性的分子，使得聚乳酸的机械和物理性能以及生物学性质与乳酸单体的立体异构性有关。

Serum levels of ADMA and its stereoisomer, symmetrical dimethylarginine, were determined using high-performance liquid chromatography.

使用高效液相色谱法测定ADMA及其立体异构体对称二甲基精氨酸的血清浓度。

Uses: Lutein, and its naturally occurring stereoisomer zeaxanthin, is used as part of a general carotenoid defense against oxidative stress, whether solar or metabolic.

用途： 叶黄素和其立体异构体玉米黄质，作为常规类胡萝卜素的一部分，用于防止来自日光的或者来自新陈代谢的氧化压力。

The optical activity of a stereoisomer is expressed quantitatively by its optical rotation, The specific rotation 〖α〗D25C of an optically active compound is defined thus

立体异构体的光学活性是以旋光度定量表示的，光学活性物质的比旋光度〖α〗D25C是这样定义的

The other stereoisomer rotates plane-polarized light to the same extent but to the right and is called the dextrorotatory isomer, designated.

另一立体异构体使平面偏振光向右旋转称为右旋，标记为。

The other stereoisomer rotates plane- polarize d light to the same extent but to the right and is called the dextrorotatory isomer, designated.

另一立体异构体使平面偏振光向右旋转称为右旋，标记为。

B (1R,3S)-1-ethyl-3-bromocyclopentane,andan optically active stereoisomer of 1,3-diethylcyclohexane.

答：指出1-甲基萘的所有手性中心，它存在多少个立体异构体

Stereoisomerism is encountered in the homologous series.

在同系列中存在立体异构现象。

Accordingly, in the original reaction (formation of B from cyclopentadiene and benzoquinone) Diels and Alder found only one of the following six conceivable stereoisomers of B.

因此，在该原始反应中(即通过P-苯醌和过量的环戊二烯生成B)，Diels and Alder发现在他们推测的六个立体异构中，只有一个出现。

The present invention concerns the compounds having the formula N-oxides, salts, stereoisomeric forms, racemic mixtures, prodrugs, esters and metabolites thereof, wherein R1 and R8 each are H, optionally substituted C1-6alkyl, C2-6alkenyl, C3-7cycloalkyl, aryl, Het1, Het2; R1 may also be a radical of formula (R11aR11b)NC(R10aR10b)CR9-; t is 0, 1 or 2; R2 is H or C1-6alkyl; L is -C-,-O-C-,-NR8-C-,-O-C1-6alkanediyl-C-,-NR8-C1-6alkanediyl-C-,-S2-,-O-S2-,-NR8-S2 ; R3 is C1-6alkyl, aryl, C3-7cycloalkyl, C3-7cycloalkylC1-4alkyl, or arylC1-4alkyl; R4 is H, C1-4alkylOC, carboxyl, aminoC, mono- or di(C1-4alkyl)aminoC, C3-7cycloalkyl, C2-6alkenyl, C2-6alkynyl or optionally substituted C1-6alkyl; R5 and R6 are H or C1-6alkyl.

本发明涉及右式化合物其N-氧化物、盐、立体异构形式、外消旋混合物、前药、酯及代谢物，其中R 1 及R 8 各是氢、C 1-6 烷基、C 2-6 烯基、C 3-7 环烷基、芳基、Het 1 、Het 2 ；R 1 也可以是式(R 11a R 11b )NC(R 10A R 10b )CR 9 -之基；t是0、1或2；R 2 是氢或C 1-6 烷基；L是-C-、-O-C-、-NR 8 -C-、-O-C 1-6 烷二基-C-、-NR 8 -C 1-6 烷二基-C-、-S 2 -，-O-S 2 -、-NR 8 -S 2 -；R 3 是C 1-6 烷基、芳基、C 3-7 环烷基、C 3-7 环烷基C 1-4 烷基或芳基C 1-4 烷基；R 4 是氢、C 1-4 烷基OC、羧基、氨基C、一-或二(C 1-4 烷基)氨基C、C 3-7 环烷基、C 2-6 烯基、C 2-6 炔基或任选被取代的C 1-6 烷基；R 5 及R 6 是氢或C 1-6 烷基。

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。