选择性

SAA ligand Lh could induce asymmetric addition of terminal alkyne to aldehydes without using air-sensitive Ti4and expensive Zn2.with good result of high yield (up to 99%) and good enantioselectivities (up to 84%ee).

将SAA配体Lh应用于在无Ti_4和Zn_2的条件下促进端基炔对醛的不对称加成反应中，反应的收率普遍较高，最高达99%，对映体选择性高达84%ee。

The industrial synthesis of 1, 4-butanediol from allyl alcohol involves two steps with low yield and selectivity.

目前工业上都是采用两步法由丙烯醇生产1，4-丁二醇，效率低，选择性差。

Low concentration of allyl alcohol helped to increase the reaction rate and high concentration of H2O2 could decrease the selectivity to glycidol using water as a solvent.

当催化剂用量一定时，以水为溶剂，较低的烯丙醇浓度更有利于反应的进行，而较高的双氧水浓度则会降低产物的选择性。

The resin was used as a selective oxidant for oxidation of allyl alcohol to allyl aldehyde.

合成了铬酸氢根季铵盐树脂，以它作为一种选择性氧化剂应用于烯丙醇的氧化反应，考察了温度、时间、溶剂、树脂与醇的物料比对氧化反应的影响。

It was found that the stereoselectivity of this reaction to produce S-CHBE could be remarkably improved by pretreatment with heating and allyl alcohol.

而烯丙基溴预处理可以使反应立体选择性从通常的生成S-型产物过量转变为R-型产物过量，优化处理条件后能使R-CHBE的e.e。

It is possible to achieve the conversion of allyl chloride and selectivity for epichiorohydrin as high as 99% on Ti-MWW.

在Ti-MWW催化剂上烯丙基氯的转化率和环氧氯丙烷的选择性都能达到99%以上。

When ligands with only planar chirality were used in the two model reactions (allylic alkylation and amination), comparatively high enantioselectivities were obtained.

令人鼓舞的是设计合成的只具有平面手性的膦氮配体，也可以取得中等到良好的对映选择性。

Synthesis and application of 1, 1'-ferrocene P, N -ligands in enatio- and regio-selective palladium-catalyzed allylic substitution reactions

1， 1'-二茂铁膦氮配体的合成及其在不对称区域选择性钯催化烯丙基取代反应中的应用

The action mechanism that (NaPO3)6 depresses almandine is two sides: one is that (NaPO3)6 is chemical adsorbed firmly on the surface of almandine and lead to almandine strong hydrophilic. The other is that (NaPO3)6 selectively dissolves Ca(superscript 2+) on almandine surface and makes the surface cations act with the collector lessening.

NaPO36对石榴石的抑制作用存在两种机理：其一，(NaPO3)6与石榴石表面Fe(上标 2+)发生化学键合导致其牢固吸附而使石榴石表面强烈亲水：其二，(NaPO3)6选择性溶解石榴石表面Ca(上标 2+)导致石榴石与捕收剂作用的表面活性质点减少。

Certainly, during the process of implementing, there are some possibilities of alterative or elective enforcements, but they can not change the basic facts that the center policies have been enforced at the grassroots levels.

当然在实施过程中会有一些变通或选择性执行的可能，但这些可能并不会改变中央政策得到执行的基本事实。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。