查询词典 asymmetric

In this thesis, several novel reaction-controlled chiral phase-transfer catalysts were designed and synthesized from readily available materials, and were used in the asymmetric epoxidation of unfunctionalized olefins and chalcone.

本文以有机合成方法学为目标，从廉价的原料出发，合成出几个新的反应控制的手性相转移催化剂，并且检验了他们在催化烯烃的不对称环氧化中的催化效果。

Meanwhile, the β-cyclodextrin- modified chiral amine salt also exhibited the chiral inducibility in asymmetric epoxidation of chalcone.

通过共价键负载于β-环糊精的手性胺在查尔酮的不对称环氧化反应中也显示出立体诱导作用。

So the key of asymmetric reaction is design and synthesis of the chiral ligands.

因此，手性催化反应的关键是手性配体的设计与合成。

Asymmetric synthesis using chiral phase transfer catalyst is a new method that has just been developed in recent years.

利用手性鎓盐作为相转移催化剂进行不对称合成是近年来刚刚发展起来的一种新的合成方法。

Dehydration process based on hollow fiber composite membrane is one of the crucial and effective methods to remove water vapor from industrial gases such as light hydrocarbon, compressed air, natural gas and so on. Dehydration of propylene with VP method was studied in the thesis. We prepared the PVA/PS、CS/PS and PVA-CS/PS hollow fiber composite membranes by spread method. The permeation behavior of water vapor among coagulable light hydrocarbons through composite membranes and asymmetric membrane was researched by vapor permeation method. Also a differential mathematical model was established which can describe dehydration of gas phase propylene.

本论文以采用蒸气渗透法脱除丙烯中微量水分为目标，制备了 PVA/PS、 CS/PS、PVA-CS/PS 中空纤维复合膜；研究了可凝性轻烃蒸气中的微量水分在复合膜、非对称膜中的渗透行为，建立了描述丙烯气相脱水的数学模型，并进行了模拟计算；深入探讨了水蒸气在交联 PVA 致密膜中的渗透机理。

Dehydration process based on hollow fiber composite membrane is one of thecrucial and effective methods to remove water vapor from industrial gases such aslight hydrocarbon, compressed air, natural gas and so on. Dehydration of propylenewith VP method was studied in the thesis. We prepared the PVA/PS、CS/PS andPVA-CS/PS hollow fiber composite membranes by spread method. The permeationbehavior of water vapor among coagulable light hydrocarbons through compositemembranes and asymmetric membrane was researched by vapor permeation method.Also a differential mathematical model was established which can describedehydration of gas phase propylene.

本论文以采用蒸气渗透法脱除丙烯中微量水分为目标，制备了 PVA/PS、CS/PS、PVA-CS/PS 中空纤维复合膜；研究了可凝性轻烃蒸气中的微量水分在复合膜、非对称膜中的渗透行为，建立了描述丙烯气相脱水的数学模型，并进行了模拟计算；深入探讨了水蒸气在交联 PVA 致密膜中的渗透机理。

We also find that the coseismic displacement amplitudes are asymmetric across the seismic fault, with the displacements south of the fault about 10%～20% larger in amplitude than that north of the fault.

我们还发现形变沿断层两盘并不对称，断层南盘的位移比北盘大10%~20%。

The systems include application sub-system and cretification authority, application sub-system apply symmetric and asymmetric cryptosystem and public-key certificate which was authoticated by CA and can certify the valid user-identity to set up secure communication channel, exchange session key and provide message integrity, confidetiality, authentication and nondeniability.

系统包括证书中心和应用子系统，证书中心签发证书用来证明用户的合法身份，应用子系统应用证书和对称、非对称密码体制，识别用户合法身份，建立了安全通信通道和交换会话密钥，实现了通信数据的完整性、保密性、真实性、不可否认性。

Experimental study is practiced to examine AWJ cutting quality.By changing waterjet pressure and cutting speed,cutting kerf surface quality is studied.By the analysis of AWJ cutting mechanism and cutting process,the thesis explores the specific shape of the cutting section and its mechanism,and believes that the asymmetric distribution of abrasive jet's kinetic energy and jet's deflexion causing the formation of striations,waviness and cuspidate end.However,high-efficient cutting of AWJ could be achieved by...

对磨料水射流的切割质量进行了试验研究，通过改变水射流压力、切割进给速度来研究切割断面质量，对AWJ切割机理和切割过程进行了分析，探讨了AWJ切割断面的形貌特征及其形成机理，认为是射流断面磨料动能的分布不均和射流的偏转滞后造成了AWJ切割断面斜条纹和曲线及尖角处的尖端，提出了两种提高磨料水射流切割质量的方法。

Two asymmetric photochemical reactions were investigated in such medium: photochemical reduction of phenyl cyclohexyl ketone and photoelectrocyclization of tropolone methyl ether.

虽然固相光化学反应的手性诱导取得了可喜的进展，但对底物和诱导剂的要求比较苛刻，使其适用范围非常有限。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失