查询词典 selectivity

The effects of increasing the stereospecilicity is due to deactivation of different selectivity for both atactic and isotatic active centers and the deactivation of atacitic active centers is much greater than that of isotactic active centers.

EB、DIBP和TMP用作Din的效果则各不相同。烷氧基硅烷等Dex提高等规度的作用是由于它们选择性地使无规活性中心失活大大高于等规活性中心。

In the historical evolution of mathematic thought, content and method, m athematic truth has assumed some postmodern characteristics.The targets of the pursuit of mathematic truth have changed from the objectives and valu es of metaphysics to the relative and varied theoretical constructions.Mat hematic truth is an open system with different levels and frameworks. It h as transcended the scope of natural truth and has generated a new dimensio n,i.e.,selectivity.Both formalization and non-formalization are effec

在数学思想、内容与方法的历史性变革过程中，数学真理的观代性开始发生转向，逐步表现出一些后现代特征：数学真理从追求形而上学的目标与价值转向追求相对的、多样化的理论构建；数学真理是一个具有不同层次性和等级结构的开放体系；数学真理超越了自然真理的范畴，开始生长出一种新维度——可选择性；形式化与非形式化都是获得数学真理的有效手段。

The wavelet transform suffers from the limitation of poor directional selectivity. To overcome this disadvantage, a novel scheme with joint Contourlet and Bandelet transform is proposed.

针对小波变换方向选择性差的局限，提出了一种基于Contourlet的Bandelet变换。

The results showed that the carbon membranes preoxidized at 460℃,30min,and carbonized at 650℃reached the highest permeability.The permeabilities of H_2,CO_2,O_2,N_2 were 1016.4、710.3、187.8、14.0 Barrer1 Barrer=10~(-10cm~3·cm·cm~2·s~(-1)·cmHg~(-1),respectively.The carbon membranes preoxidized at 460℃,30 min,and carbonized at 850℃reached the highest selectivity.The ideal separation factors of H_2/N_2、CO_2/N_2,O_2/N_2 were 129.2、93.1、21.9、respectively.

结果表明：PPESK前驱体经460℃，30 min预氧化处理，650℃炭化得到的炭膜气体渗透性最佳，H_2、CO_2、O_2、N_2的渗透系数分别达到了1016.4、710.3、187.8、14.0 Barrer1 Barrer=10~(-10cm~3·cm·cm~(-2)·s~(-1)·cmHg~(-1)；经460℃，30 min预氧化处理，850℃炭化得到的炭膜气体选择性最佳，H_2/N_2、CO_2/N_2、O_2/N_2的分离系数分别达到了129.2、93.1、21.9。

Under the optimum reaction conditions,:benzalacetone:Ru:KOH=1000:1:20, 2 MPa, 30℃, and 2h, the conversion and the selectivity toward the unsaturated alcohol was reached 99% and 99%, respectively, and the ee value of unsaturated alcohol was over 58.9%.

在优化的反应条件下，苄叉丙酮加氢反应的转化率大于99％，生成α，β-不饱和醇的选择性大于99％、对映选择性达到了58％ee以上。

The catalytic activity and selectivity for hydrodesulfurization and hydrodenitrogenation were studied by using benzothiophene, dibenzothiophene and quinoline as model compounds.

在N2-H2下，利用程序升温还原氮化反应制备氧化铝负载的β-Mo2N0.78催化剂，并以苯并噻吩、二苯并噻吩和喹啉为模型化合物，考察该催化剂的加氢脱硫、加氢脱氮活性和选择性。

The result indicates that the hydrogen bond formed by Arg24 in PTP-1B and benzotriazole molecules is of great importance for the selectivity of the compounds.

计算结果表明PTP-1B中的Arg24与化合物的氢键相互作用是提高选择性的重要因素，并且在R2位引入氢键供体且体积较大的强供电子基团，将有利于化合物抑制活性的提高，而在R2位取代基的末端引入氢键受体且体积较大的强吸电子基团，将有利于化合物选择性的提高。

Benzotriazole derivatives were found to be potent PTP-1B inhibitors, which provide a moderate degree of selectivity to PTP-1B over TCPTP.

苯并三唑类化合物对PTP-1B的抑制活性很高，并且其中一些化合物对PTP-1B表现出了较好的特异选择性，具有良好的药用开发前景。

Moreover,the selective oxidation of primary and secondary alcohols to corresponding carbonyl compounds with the multinuclear copper complexes Cul-Cu4 as catalysts have been conducted using TBHP and O_2/TEMPO,respectively.Among them,the copper complex Cu3 showed the best performance.On the performances of the two classes of oxidants,benzylic and heterocyclic alcohols could be effectively oxidized to carbonyl compounds.Specifically,the secondary alcohols could be effectively oxidized to ketones with excellent selectivity up to 100%in the presence of TBHP and the allylic alcohols could be effectively oxidized to aldehydes in the presence of O_2/TEMPO system.

实验结果还表明，在TBHP或O_2/TEMPO存在下，各配合物催化剂均能使各种取代芳香伯/仲醇以及杂环醇等以不同程度的转化率和选择性转化成相应的醛或酮，其中，配合物Cu3在O_2/TEMPO存在下可使苯甲醇和烯丙醇等以较高转化率和近100%的选择性转化成相应的醛，而对其它芳香醇和脂肪伯/仲醇等的催化性能则较差；在TBHP存在下，配合物Cu3则可使1-苯乙醇和其它仲醇以较高转化率和近100%的选择性转化为相应的酮，但对各类其它伯醇选择氧化的性能相对较差。

When bromine was used to bromization reaction with 4-acetyl-guaiacol,the product bromide incompletely or super bromide partial,and the selectivity was poor.

使用单质溴与4-乙酰基愈创木酚进行溴化反应时，产物溴化不完全，或者局部过量的溴化，且选择性较差。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。