一步

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。

In the course of tough experiment , I have learned calmness , diligency .

在艰苦的实验阶段，我学会了冷静、执着、坚韧不拔，让我深刻认识到人要用心地去做每一件事，认真、踏实地面对人生的每一步。

A series of segmented thermally stimulated shape-memory polyurethanes, which consist of polyethylene adipate glycolas the soft segment and 4,4'-diphenylmethane diisocyanate-1,4-butanediol-DPA(which consists of ring components) as the hard segment were synthesized by one-step polymerization.

以聚己二酸乙二醇酯二醇为软段、4，4' -二苯基甲烷二异氰酸酯 1，4 丁二醇含环状结构的扩链剂DPA为硬段，采用一步聚合法制备了一种具有热致形状记忆功能的多嵌段聚氨酯弹性体。

A slow wave of recognition crossed his face, and he stood back and looked at me."Moneypenny?" he said, almost disbelievingly.

他脸上缓缓滑过一丝认出来的神情，然后退后一步看着我，带着几乎难以置信的口吻说道：钱眼？

Death's forecome shroud is tangled round my feet,And if I step or stir, I touch the end.

只要我跨出一步或者稍一走动，我便到了尽头。

We braved the gelid night, slipping and sliding over pavements at a bustling train station to buy soft-seat tickets to Yabuli.

夜里，我们冒着严寒、在繁忙的火车站里一步一打滑，买去亚布力的软座票。

Forexample, when you love someone, c ges are all around. Then I stepbackward and watching it silently, then I see the true feelings.

比如爱一个人，充满变数，我于是后退一步，静静的看着，直到看见真诚的感情。

The DNA molecular tweezers could then be operated to interact with a DNA structured object at lowered pH.The DNA object helically wrapped around the tweezers\' arms and was then firmly held after the tweezers being zipped close.

本工作为将DNA纳米镊从纯粹概念的演示推进到开发接近实际功能的应用这一DNA纳米机器研究的长远目标迈出了重要的一步。

He said it represents the first time an investigational H.I.V.

一位博士说：我们已经向成功迈出了重要的一步。

Which the concussion had knocked off, and backing, and knuckling his forehead, pleased that it was an accident

毕仄捡起了他那顶被撞下来的帽子，退后一步，用指节摸了一下头，庆幸这是出于无意。

We have no common name for a mime of Sophron or Xenarchus and a Socratic Conversation; and we should still be without one even if the imitation in the two instances were in trimeters or elegiacs or some other kind of verse--though it is the way with people to tack on 'poet' to the name of a metre, and talk of elegiac-poets and epic-poets, thinking that they call them poets not by reason of the imitative nature of their work, but indiscriminately by reason of the metre they write in.

索夫农 、森那库斯和苏格拉底式的对话采用的模仿没有一个公共的名称；三音步诗、挽歌体或其他类型的诗的模仿也没有——人们把&诗人&这一名词和格律名称结合到一起，称之为挽歌体诗人或者史诗诗人，他们被称为诗人，似乎只是因为遵守格律写作，而非他们作品的模仿本质。

The relationship between communicative competence and grammar teaching should be that of the ends and the means.

交际能力和语法的关系应该是目标与途径的关系。