异构体

The minimal energy conformations of host-guest complexes were obtained with Tripos force field. Molecular dynamics simulations were carried out to investigate chiral molecular recognition and the distribution of hydrogen bonds. The energies of recognition system were calculated with MM+ force field as well.

首次将分子力学方法引入卟啉的手性分子识别领域的研究；用Tripos力场研究了主客体配合物最低能量构象，比较了同一主体与互为对映异构体的两个氨基酸甲酯形成的配合物的能量差异；用分子动力学模拟方法研究了手性分子识别行为及体系的氢键分布；用MM+力场研究了识别体系的能量。

The modified QCM sensors were used to recognize the butylamine isomers in gas. The results showed that the QCM coated with both compounds had preferential affinity to n -butylamine, then i -butylamine, t -butylamine in the range of low concentrations, indicating that in the recognition process, the steric hindrance effect played an important role when forming complex with guest molecules.

修饰的QCM传感器用于识别气相中不同的丁胺异构体，结果发现，在小浓度范围之内上述两种化合物修饰的QCM均优先吸附正丁胺，之后依次为异丁胺和叔丁胺，表明在形成主客体化合物的识别过程中，空间位阻效应是一个重要因素；当分析物浓度增大时，丁胺的极性和磁性成为分子识别的主要因素。

To study the bioactive components from water soluble extract of the Chinese eaglewood, various column chromatography of Chinese eaglewood led to the isolation of ten compounds. Their structures were elucidated as 2,3-bis(3-hydroxyphenyl)- propan-1-ol (1), [(2R,3R)-3-(4-amino-3,5-dimethoxyphenyl)oxiran-2-yl]methanol (2), 8-chloro-4'- methoxy-5,6,7,3'-tetrahydroxy-2-(2-phenethyl)-5,6,7,8-tetrahydrochromone (3), 4'-methoxy-5,6,7,3'-tetrahydroxy-2--5,6,7,8-tetrahydrochromone (4), the isomer of 4 (5), 4'-methoxy-5,6,7,8-tetrahydroxy-2-(3'-hydroxyphenethyl)-5,6,7,8- tetrahydrochromenone (6), 4'-methoxyisoagarotetrol (7), 6-hydroxy-2-(2-hydroxy-2- phenethyl)-chromone (8), 6-hydroxy-2-(2-phenethyl)-chromone (9), 6-hydroxy-2-(4'- hydroxy-2-phenethyl)-chromone (10), and Guaiacylacetone (11) by means of spectral analysis and comparison with references.

为了进一步发现沉香中具有生理活性的化学成分，本文对国产沉香的水溶性成分进行了研究，从中分离得到11个化合物，通过红外、紫外、质谱、核磁共振(1H-NMR， 13C-NMR， COSY， HSQC， HMBC， ROESY)波谱解析，分别鉴定为：2，3-二(3-羟基苯基)-丙-1-醇(1)，[(2R，3R)-3-(4-氨基-3，5-二甲氧苯基)-2-氧化烯基]甲醇(2)，8-氯-4'-甲氧基-5，6，7，3'-四羟基-2-(2-苯乙基)-5，6，7，8-四氢色原酮(3)，4'-甲氧基-5，6，7，3'-四羟基-2-(2-苯乙基)-5，6，7，8-四氢色原酮(4)，化合物3的差向异构体(5)，4'-甲氧基-5，6，7，8-四羟基-2-(3'-羟基-2-苯乙基)-5，6，7，8-四氢色原酮(6)，4'-甲氧基异沉香四醇(7)，6-羟基-2-(2-羟基-2-苯乙基)色原酮(8)，6-羟基-2-(2-苯乙基)色原酮(9)，6-羟基-2-(4'-羟基-2-苯乙基)色原酮(10)和Guaiacylacetone (11)。

Treatment of dials with N-tert-butanesulfinamide, all biaryl dials were successfully converted into the corresponding bis-imines which were then treated with samarium diiodide to afford diamine products. The absolute configurations of all the intramolecular coupling products were determined by X-ray crystallography.

轴手性二醛与N-叔丁基亚磺酰胺缩合得到相应的亚胺，其为一对非对映异构体。N-叔丁基亚磺酰亚胺在二碘化钐条件下得到的偶联产物，经X-衍射也确定了其立体构型。

In the forth part, the heterotactic enthalpic pairwise interaction coefficients between five amides and butanediol isomers (1,3-butanediol, 1,4-butanediol and 2,3-butanediol) at 310.15K are discussed. The change of temperature made remarkable effects on the values of h_.

第四部分：经测定得到了五种酰胺与丁二醇的三种异构体在298.15K(25℃)时的各级异系焓相互作用系数，并进行了分析比较，讨论了五种乙酰胺分子与三种丁二醇分子的相互作用机制。

In the gas phase,Pt_2CH_2~+ has only one most stable structure whereas PtAuCH_2~+ has two isoenergetic isomers.

Pt_2CH_2~+在气相中只有一种能量最稳定的构型，而PtAuCH_2~+却存在两种能量相近的异构体。

Methyl-5-ethyl-2-thiouracil,m.p.211°,was prepared according to the direc- tions of Johnson and Baily.4-Methyl-5-ethyl-uracil,m.p.236°,was formed in a 81% yield from 4-methyl-5-ethyl-2-thiouracil by boiling the latter with an aqueous solution of monochloroacetic acid.4-Methyl-5-ethyl-uracil reacted with phosphorous oxychloride and phosphorous pentachloride,giving 4-methyl-5-ethyl-2,6-dichloropy- rimidine in a 79% yield.

14-甲基5-乙基-2，6-二氯代嘧啶曾用磷醯氯和五氯化磷与其相应的2，6-二羟基嘧啶作用制取。(2)4-甲基-5-乙基-2，6-二氯代嘧啶与醇钠作用，极易转变成4-甲基-5-乙基-2，6-二烷氧基嘧啶。(3)4-甲基-5-乙基-2，6-二甲氧基嘧啶和2-氧代-3，4-二甲基-5-乙基-6-甲氧基嘧啶在高温时重排成其稳定构型的的异构体：1，3，4-三甲基-5-乙基-2，6-二氧代嘧啶。

Draw and give the stereochemical designation for the geometric isomers of 2,4-hetpadiene.

答：画出2，4-二庚烯的异构体的构型式

Geometries and energies of various low-energy conformers of the stereoisomers of 2,2,4, 4-tetrachloropentane and 2,2,4,4,6,6-hexachloroheptane were determined at the MP2 level with a 6-311++G** basis set.

在MP2/6-311++G**水平下，对2，2，4，4-四氯戊烷与2，2，4，4，6，6-六氯庚烷旋转异构体构象进行几何优化和能量计算。

On the other hand, 3(2)-fluoro-4-methoxyl methyl benzyl alcohol and 3(2)-fluoro-4-methyl benzyl alcohol are mixture and components of pyrethrum esters. Both of them have "mixture fluorine effect " and higher activity, lower drug resistance. As we know, the mixture benzyl alcohol containing fluorine is more easy to be synthesized than the single, so the cost of preparation is lower. We hope to apply it to molecule design of the new agriculture chemical. On the base of molecule design and structure-activity relationship research of pyrethric acid II and mixture of alcohol containing fluorine, we intend to get new pyrethrum ester that have higher activity and lower resistance.

另一方面，混合含氟对甲氧甲基苄醇和混合含氟对甲苄醇都是具有&混合氟效应&的高活性、低抗性的拟除虫菊酯醇组分，由于混合含氟醇的合成要比单一异构体的合成容易，成本较低，本文希望将其应用到新农药的分子设计中，用第二菊酸和一些含氟醇进行分子设计及进一步的构效关系的研究，筛选出一些高活性低抗性的拟除虫菊酯换代新品种。

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。