查询词典 valent

Further application of the partially perturbative density functional theory to MX2-NX-H2O solution indicates that the present theory is better than the Poisson-Boltzmann equation and can be used to predict the structures and ion-partitioning of high-valent ions in charged nanopores.

对混合电解质溶液MX2-NX-H2O的结果同样表明本文的部分微扰的密度泛函理论要好于传统的Poisson-Boltzmann方程，且能够预测高价离子在带电纳米孔内的结构与分配。

Progress in pinacol coupling of aldehydes and ketones using low valent titanium is reviewed in recent years.

由低价钛络合物诱发的片呐醇偶联反应，具有良好的化学选择性和立体选择性，近几年来又引起有机化学家们的极大兴趣与重视。

The aluminium powder has been used to reduce titanium tetrachloride to generate the low valent titanium reagent which can induce the reductive coupling of aldehydes and ketones to form the corresponding pinacol s.

以价廉易得的铝粉还原四氯化钛制得低价钛，将其用于醛酮还原偶联，合成了6种片呐醇，其中对称片呐醇4种，不对称片呐醇2种。

Methods for synthesizing of pinacol are reviewed,the difference of catalytic effects and stereoselectivity with various catalytic systems are introduced in this paper.Highlights are laid on the mechanism and stereoselectivity of new synthetic methods catalyzed by low valent Samarium, Titanium and Trimethyl chlorosilane, etc.

频哪醇合成新进展* The Recent Progress in the Synthesis of Pinacol 李有桂蒋昌盛尤田耙**(中国科学技术大学化学系合肥 230026)本文综述了合成频哪醇的方法，介绍了不同催化体系的催化效果和立体选择性的差异，着重介绍了低价钐、低价钛、三甲基氯硅烷等新的合成频哪醇反应的机理和立体选择性。

In this study, 340 pregnant women in the third trimester were randomly assigned to receive inactivated influenza vaccine or the 23-valent pneumococcal polysaccharide vaccine.

在这个研究中，340名孕妇在孕期第三个三个月中被随机的分配接受灭活流感疫苗或者23－价肺炎球菌多糖疫苗注射。

The results of batch experiments showed that the anaerobic biodegradation kinetics of 2-CNB and 4-CNB by granular sludge were follwed by first-order reaction. The nitro groups of 2-CNB and 4-CNB were more easily attacked by electron than chlorines and they were reductively biotransformed to amino groups under anaerobic conditions. The acclimated anaerobic granular sludge, which could dechlorinate 4-chloroanline to aniline, showed that it had the ability of para-dechlorinating. The anaerobic biodegradating on pathway of 2-CNB and 4-CNB were suggested as follows:AbstractIn ZVI(zero-valent iron, Fe0)-reduction system, the nitro groups of 2-CNB and 4-CNB were reductively transformed to amino groups.

2分批试验结果证明，颗粒污泥降解2-CNB和4-CNB遵循一级动力学，在厌氧条件下，CNB发生序列的硝基还原与脱氯作用，苯环上的硝基比氯原子更容易受到亲电子攻击，发生还原反应生成氨基；所获得的颗粒污泥具有对位脱氯活性，可使4-CA进一步脱氯形成苯胺。2-CNB和4-CNB厌氧降解的建议性途径为： ZVI(Zero-valentiron)对2-CNB和4-CNB的作用主要是将苯环上的硝基还原为氨基；在ZVI与污泥共还原转化体系中，ZVI对氯代硝基苯的硝基转化具有一定的促进作用，但因ZVI对中间产物的吸附特性，终产物形成速率趋慢。

Meanwhile, the reoxidation of low valent Mn ion in the reduced samp...

这正是该催化剂较Na2WO4／SiO2具有更高甲烷选择氧化活性的原因。

In this paper, after the similarities and differences of the three theories on semantics, including Valent grammar, Case grammar, Theta theory, are reviewed synoptically, we introduce a semantic model based on phrase-standard grammar of contemporary Chinese for a Chinese-English machine translation system.

本文在简略阐述我们对几种语义分析理论——配价语法，格语法，论旨理论的认识的基础上，介绍我们研制的一个基于汉语词组本位语法的汉英机器翻译系统所采用的语义模型。

Low valent selenium and telluronium compounds have high reducing selectivity to be used to form carbon-hydrogen bonds as special reducing reagents.

低价硒、碲化合物具有良好的还原选择性，可用于多种碳-氢键的形成，碲叶立德和α-芳硒基取代的胂叶立德均可发生Wittig型反应，是形成碳-碳双键的重要方法。

Low valent selenium and telluronium compounds have high reducing selectivity to be used to form carbon-hydrogen bonds as special reducing reagents.

低价硒、碲化合物具有良好的还原选择性，可用於多种碳-氢键的形成，碲叶立德和α-芳硒基取代的胂叶立德均可发生Wittig型反应，是形成碳-碳双键的重要方法。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。