对映体

These dendritic NOBIN derived Schiff base ligands have been applied to titanium catalyzed hetero-Diels-Alder reaction of Danishefshy's diene and aldehydes, affording the corresponding 2-substituted 2, 3-dihydro-4H-pyran-4-one in quantitative yields and excellent enantioselectivities (up to 97. 2%ee). Comparing the reactivities and enantioselectivities of reaction catalyzed by the titanium complexes of these Schiff base ligands, it was found that a series of ligands L〓 were superior to the other three series of ligands L〓, L〓 and L〓, a significant positive NLE and a dendrimer effect existed in the L〓 dendritic catalyst system. The disposition of the dendritic wedges and the dendron size in the ligands were observed to have a significant impact on the enantioselectivity of the reaction.

NOBIN衍生的树枝状大分子希夫碱手性配体与钛形成的配合物在催化不对称杂Diels-Alder反应中的应用将得到的四个系列NOBIN衍生的树枝状希夫碱三齿手性配体与四异丙氧基钛形成的配合物用于催化Danishefsky's diene与醛的不对称杂Diels-Alder反应，通过反应条件的优化，获得了定量的收率和最高达97.2％ee值的对映选择性；考察了这四个系列NOBIN衍生的树枝状希夫碱钛配合物的催化活性和对映选择性，结果发现它们的活性次序依次为L〓≈L〓＞L〓＞L〓，对映选择性次序依次为L〓＞L〓＞L〓＞L〓。

Prior to electrophoresis, the analytes were purified and preconcentrated by solid phase extraction from plasma.

血清样品通过固相萃取预处理和浓缩，对映体的固相萃取回收率在82.9%～90.7%，相对标准偏差RSD%均小于7 %。

The stereochemical studies of PPCs derived from the copolymerization of CO_2 with chiral PO at various conditions reveal that the polymer enantioselectivity is proportional to its head-to-tail linkages with regard to regioselective ring-opening of the epoxide.

通过研究聚碳酸酯的立体化学发现聚合物的对映体选择性与环氧丙烷区域选择性开环存在一定的影响作用。

Chinese Academy of Inspection and Quarantine, Beijing 100025, China Abstract: This article reviewed the development of fipronil and its metabolites, emphasizing the fate of environment, action of fipronil and toxicology of antimer and metabolites.

中国检验检疫科学研究院，北京 100025 摘要：综述了氟虫腈及其代谢物近年来的研究进展，涉及氟虫腈及其代谢物在环境中的迁移与转化、氟虫腈的作用机理、对映体的毒性差异。

The present paper dealswith the preparation of surfactant (deoxycholic sodium and tetrabutylammonium bromidemixture) coat bonded to silica gelwith alkyls aswell as its application to the separation of chiral enantiomers.

提要： 研究脱氧胆酸钠和溴化四丁铵的混合态表面活性剂涂层烷基键合硅胶固定相的制备和它在手性对映体分离中的应用。

The enantiomeric excess of the epoxides was still 51% even after the catalyst was used three times.

催化剂在使用四次后，对映体过量值仍能达到51%。

The effect of structural variation of the solutes on their separation and retention was noted.

此外，还建立了手性农药喹禾灵和重要药物前体DL-苯丁氨酸乙酯对映体纯度的测定方法。

Direct enantiomeric separation of racemic mixtures of 13 β-amino alcohols and β-hydroxy sulfides was achieved by HPLC using Chiralcel OD, Chiralcel OJ and Chiralpak AD as chiral stationary phases and hexane/2-propanol mixture as eluent. These racemates were completely separated into enantiomers at least on one of these stationary phases.

在以正己烷-异丙醇为移动相的体系中，用ChiralcelOD，ChiralcelOJ及ChiralpakAD作为手性固定相对13种β-氨基醇及β-羟基硫醚类化合物对映体进行HPLC手性拆分，这些化合物至少能在一支柱上得到基线级分离。

The effects of isopropanol concentration in the mobile phase on the retention and resolution were investigated.

用正相高效液相色谱法在该固定相上首次直接拆分了触杀型苗后除草剂氯氟草醚乙酯对映体。

Under above mentioned conditions, the initial reaction rate and enantiomeric ratio of the reaction are 5.88 mmolL^(-1)h^(-1) and 83. After reaction time of 6h, the yield and the product e.e.

在上述条件下，反应初速度和对映体选择比分别为5.88mmolL^(-1)h^(-1)和83，反应6h，产率为47.6%，产物e.e。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。