单分子的

On the basis of the kinetic equation of substrate reaction in the presence of urea or guanidine hydrochloride, all microscopic kinetic constants for the free enzyme and enzyme-substrate binary and ternary complexes have been determined. The results of the present studies indicate that:①In the presence of urea or guanidine hydrochloride, enzyme-substrate complexes lose their activity less rapidly than the free enzyme. Therefore, both substrates, NADPH and 7, 8-dihydrofolate, protect dihydrofolate reductase against inactivation.②The denaturation of dihydrofolate reductase by urea follows single-phase kinetics, and changes in enzyme activity and tertiary structure proceed simultaneously in the unfolding process, so it may be an"all or none"process.③The GdnHCl-induced unfolding of the dihydrofolate shows a biphasic transition, while the change in the enzyme activity is a single exponential process. The rate constant of inactivation is consistent with that of the fast conformational change. Therefore, the kinetic intermediate of protein unfolding should be a partially folded and inactive form.

我们根据在脲或盐酸胍存在下的底物反应动力学方程求得游离酶和酶底物二元、三元复合物的微观动力学常数，结果表明：①酶-底物二元、三元复合物的失活速度明显慢于游离酶，说明两个底物二氢叶酸和NADPH对酶的失活都具有一定程度的保护作用；②在脲作用下，酶的失活和构象变化均为单指数项过程，而且酶的活力丧失和三级结构变化是同时发生的，说明二氢叶酸还原酶的脲变性可能是一个"全或无"的两态过程；③在盐酸胍作用下，酶的构象变化为两相过程，而失活则是单指数项过程，酶分子构象变化的快相速度常数与失活速度常数基本一致，因此我们认为二氢叶酸还原酶的盐酸胍变性过程中存在一个没有活力、但仍具备一定空间结构的变性中间体。

The immiscibility for A gum of xanthan may be correlated with the strong intermolecular hydrogen bonds themselves such as double-strand chain forxanthan and aggregation for A gum.

单胞菌和黄原胶共混相容性差是由于它们各自的分子间氢键较强，本身易形成聚集体或双螺旋体。

The Diels-Alder cycloadditions of [60] fullerene for preparation of optical limitingmaterials are discussed in chapter 3 and 6. Soluble cycloaddition derivatives of 〓aresynthesized by the reaction of 〓 with indene,1,1'-biindene andcyclopentadiene derivatives.〓Particular, the Diels-Alder cycloaddition of 〓 with1,1'-biindene under controlled conditions affords the stable monoadduct 〓〓of novel structure, which was confirmed by HPLC, FTIR, FD-MS,〓NMR,〓 NMR, HMQC and HMBC spectra, Its two bridgehead cage carbons resonate at70.91ppm, The 〓 NMR spectra showed 38 lines consistent with the 〓 symmetryassociated with [6,6] addition. The 〓 shows similar optical limitingproperties to that of 〓 in toluene for 8ns laser at wave length 532nm. Moreover, thehigh solubility of this adduct in polar solvents such as THF, acetone enables itsincorporation into sol-gel glass matrix. The thin films prepared via the sol-gel methodshow improved OL behaviour compared to those of 〓. The langmuir-Blodgett filmformation and uv-visible absorption of 〓 are also investigated. LBmonolayer of this compound is prepared on the air-water interface at 〓 mol/l. In chapter 4, three water-soluble derivatives of [60] fullerene: fullerol(1), theaddition product (2)of fullerol (1)with polyvinylpyrrolidone and fumaric acidderivative of 〓(3) are synthesized and characterized.

通过Diels-Alder环加成反应，用茚〓和1，1'-联茚〓及取代茂合成了一系列可溶性的〓环加成衍生物，发现可控制反应条件，使1，1'-联茚与〓反应，并高产率地得到具有新颖结构的单加成物，用HPLC、FTIR、FD-MS 及〓、HMQC、HMBC等多种波谱技术对其结构进行表征，测得它的两个〓杂化的桥头碳的化学位移为〓ppm，证明生成的衍生物为6∶6闭式环加成，〓NMR谱中共给出38个信号，表明〓联茚衍生物分子具有〓对称性；在波长532nm，脉冲宽度8ns的激光下，〓联茚衍生物的甲苯溶液的光限幅性能与〓的甲苯溶液相近，由于〓联茚单加成衍生物熱稳定性好，在四氢呋喃，丙酮等极性溶剂中溶解性好，能分别均匀地掺入溶胶-凝胶中，已发现它的溶胶(so1)光限幅性能优于纯〓的光限幅性能；使用Langmuir-Blodgett技术将〓联茚衍生物在空气和水的界面进行了LB单层膜和多层膜实验以及UV-Vis吸收谱研究，通过等温压缩曲线测试，证明浓度为〓〓时，〓联茚衍生物能够形成单层膜。

The molecular phylogenetic trees indicated that Oedipodinae is a monophyletic group and this subfamily is a natural one, but Catantopinae and Acridinae are non-monophyletic. Oedipodnae is a relatively primitive group within the Acrididae, whereas the Oxyinae may have diverged later than Oedipodinae, but earlier than most other species of Acridide.

分子系统树表明：斑翅蝗亚科是一单系群，该亚科是一个合法的亚科，但斑腿蝗亚科和蝗亚科都不是单系群；斑翅蝗亚科在蝗科内是一个相对原始的类群，而稻蝗亚科比斑翅蝗亚科相对进化，比蝗科的其他亚科的种类相对原始。

China and sect. Coilanthns. With the results of ITS and matK gene trees, it is supported that the possible evolutionary tendency of inflorescences is from spike to single umbel and raceme of umbels in Smilax.

DNA分子树结果支持圆锥花序可能是由单伞形花序的祖先通过其花序基部的叶子退化而演变来的，而这种单伞形花序是菝葜组和土茯苓组的共有特征。

The 28S rDNA molecular phylogenetic trees showed: 1 entoprocts and phylactolaemate ectoprocts constituted a sister group, strenghthening the opinion that entoprocts should be reunited into phylum Bryozoa; 2 the cheilostome gymnolaemates was obviously non-monophyletic; 3 bryozoans itself was polyphyletic beyond any doubt, its main lineages were scattered in different positions of the lophotrochozoan trees; 4 to our great interests, the phylogenetic position of cheilostomes was between the diploblastic and the triploblastic, indicating they may play an important role during the evolution route from the diplobastic to the triploblastic animals.

28S rDNA分子系统树显示，内肛动物和被唇类外肛动物聚在一起并互为姐妹群，支持将内肛动物重新归入苔藓动物门的结论；唇口目裸唇类外肛动物绝非单系发生；苔藓动物本身也不是单系发生的，其主要类群分别位于触手冠担轮动物系统树的不同位置，特别是，唇口目苔藓动物的系统地位介于二胚层动物和其它三胚层动物之间，可能是二胚层动物向三胚层动物演化过程中的一个关键类群。

This supported that Stemonaceae should be separated from Liliales and placed in Pandanales. Affinities and speciation of the species in Croomia The two Asian species of Croomia were more closely related to each other than either is to Northern American species.

Croomia的种间关系该属的3个种中，北美的C.pauciflora与两个亚洲种在分子树上已经分歧，根据单倍型和分子树该种与亚洲种的分离时间较早，很可能是从C.japonica的日本居群衍生形成或迁移到北美大陆的。

In chapter four, the preperation of ytterbium diiodide was examined. The reductive cleavage of Se-Se bond and S-S bond induced by ytterbium diiodide was investigated. The reaction of diselenides and disulfides with allylic bromide promoted by ytterbium diiodide was also examined. The intermolecular Barbier-type reaction induced by ytterbium diiodide was studied. In the last section of this chapter, the intermolecular reductive coupling of nitriles with azides induced by samarium diiodide was investigated.

第四章，研究了二碘化镱的制备方法，以及二碘化镱作为一种优良的单电子转移试剂在有机合成中的应用：二硒醚的Se--Se键和二硫醚S-S键的还原断裂，及其在合成烯丙基硒醚，硒代酯和烯丙基硫醚，硫代酯中的应用，实验结果表明二碘化镱也能促进分子间的Barbier反应，而文献认为二碘化镱不能促进分子间的Barbier反应；最后研究了二碘化钐促进的叠氮化合物与腈的交叉还原偶联反应，一步高收率地制备脒的方法。

The results are as follows:(1) immunoreactive neurons of NPY in medulla oblongata of Taihe silky fowl, New jianghan domestic chicken are mainly localized in the inferior olivary nucleus.

结果如下：(1)在泰和乌鸡和江汉鸡的延髓中，NPY阳性神经元主要存在于下橄榄核，网状核及中缝核也少量出现；(2)在泰和乌鸡和肉鸽的小脑中，NPY阳性神经元主要存在于小脑皮质的蒲肯野氏细胞层，且以小叶顶端的蒲肯野氏细胞阳性明显，而小脑皮质的分子层、颗粒层未见阳性反应细胞；(3)泰和乌鸡延髓的网状细胞核非常发达；泰和乌鸡小脑皮质分3层，由外至内依次为分子层、蒲肯野氏细胞层和颗粒层；小脑分10叶，Ⅰ、Ⅱ和Ⅹ为单叶，其余各叶都分为2～3个小叶；(4)非洲鸵鸟迷走神经运动背核和疑核特别发达，孤束核吻侧部不发达。

To attaining longlived charge separated states, the new compounds 7 and 8 of C60-S-2-thioxo-1, 3-dithioles derivatives were synthesized by Diels-Alder cycloaddition reaction. The structures generated by AM1 were used as the initial configurations for the density functional optimization at the B3LYP/3-21G level for all carbon and sulfur clusters, and some geometry conformation indexes were obtained. We found that C60 has been half-packed by the curved 2-thioxo-1, 3-dithioles derivatives.

为了获得具有长寿命电荷分离态的[60]富勒烯－富硫衍生物有机功能分子，我们设计了用单键硫桥键联[60]富勒烯和硫酮衍生物的分子7和8，用半经验AM1方法得出最低能量的几何结构，在此基础上用密度泛函 B3LYP/3-21G方法，对其进行计算，得出电子相关的优化参数，预测其稳定性。

The labia have now been sutured together almost completely.The drains and the Foley catheter come out at the top.

此刻阴唇已经几乎完全的缝在一起了，排除多余淤血体液的管子和Foley导管从顶端冒出来。

To get the business done, I suggest we split the difference in price.

为了做成这笔生意，我建议我们在价格上大家各让一半。