共查询到20条相似文献，搜索用时 140 毫秒
1.
首次报道了N^3－2－氰基乙基－N^1，N^5－二乙酰基二乙基三胺的合成方法。合成此化合物的意义在于将二乙基三胺两端之氨基保护后，从其中间的N^3原子上接一条碳链，再通过这条碳链将DNA之切割基因二惭基三胺与DNA识别系统相连接，这样即可增加二乙基三胺的柔性，增大其切割活性，从而可进一步开发出一系列定位切割DNA的化学核酸酶。 相似文献
2.
N-(2-氯苯基)-N1-(1,2,4-三氮唑)脲的合成 总被引：2，自引：0，他引：2
以2－氯苯甲酸为原料，经过Curtius重排反应制得2－氯苯异氰酸酯，再进一步与3－氨基－1H－1，2，4－三氮唑发生亲核加成反应，合成了目标化合物N－（2－氯苯基）－N^1-(1,2,4-三氮唑）脲，其产率为72％。对目标化合物经元素分析，IR和^1HNMR表征。 相似文献
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报道了水溶性新显色剂1－（5－硝基－2－吡啶偶氮－2，7－萘二酚－6磺酸（5－NO2－PADN－S）的制备方法；并初步探讨了5－NO2－PADN－S的性质及其与金属离子显色反应的光度特性。结果表明，该试剂在pH6．2的HAc-NaAc缓冲溶液中可与Fe^2 、Co^2＋、Ni^2 、Pd^2 等金属离子在水溶液中直接发生显色反应，生成稳定的有色配合物。 相似文献
4.
1－溴丁烷制备实验中存在以下副产物，1－丁烯，2－丁烯，正丁醚，2－溴丁烷和Br2，并对产生的机理进行了探讨。 相似文献
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周立人 《海南师范学院学报》2001,14(4):85-88
合成了二种新的5－取代1，10－菲咯啉化合物phen－NHCO（CH2）nBr(n=9,11），它们是高效的分析化学试剂、钌（Ⅱ）类电化学发光（ECL）传感器活性材料的配体。利用元素分析、红外光谱、核磁共振氢谱和激光解析电离飞行时间质谱确证了其组成和结构。 相似文献
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由锡基炔化合物和Ｃｐ２Ｚｒ（Ｈ）Ｃｌ（Ｃｐ＝η＾５－Ｃ５Ｈ５）反应，生成（Ｚ）－１－锡基烯基锆化合物，进而与芳基硫氯化反应，合成了（Ｚ）－１－锡基烯基芳基硫醚，产率中等至良好。 相似文献
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通过相转移催化下的芳基醚合成，由对－烷氧基苯甲醛，对－烷氧基苯胺分别与对－苯二胺和对－苯二甲醛发生亲核加成反应，合成了12个中心桥连基为西佛碱，含有3个苯环，不同刚性实结构及不同末端链长的西佛碱化合物，并通过DSC和偏光显微镜对其介晶性进行了表征，研究表明，末端链长度及刚性实结构对相应变温度和清亮温度均有影响，但末端链长度对相变温度和清亮点温度影响较小，刚性实结构对相变温度和清亮点影响较大。 相似文献
8.
本报道了用2，3－二甲吡嗪和正庚酸在自由基引发剂引发下合成5－己基－2，3－二甲吡嗪的新合成方法研究，并对合成条件进行了探索。实验表明：该方法具有产率高、路线短、分离精制简单等优点，是合成5－己基－2，3－二甲吡嗪的有效方法。 相似文献
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文章综述了质谱技术的新进展与CZE／MS／MS，MALDI－TOF－MS，LC－ESI－MS等质谱新技术及它们在生命科学中的应用，指出这些质谱新技术已被证明在多肽和蛋白质的鉴定、单核苷酸、核酸、糖蛋白的分析等领域是很有效的工具。 相似文献
10.
马淮凌 《商丘师范学院学报》2002,18(5):81-82
研究了1－羟基1，1－二磷酸乙烷的合成及其钠盐的制备，合成方法为一步合成法，该方法采用三氯化磷和醋酸为起始原料，操作简单、快速，产率为理论值的90％。 相似文献
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邱崇丙 《唐山师范学院学报》2014,(1):21-23
汉字的六书,《说文》对“转注”一类,语焉不详。后世学者提及转注,也仅限于许慎所举出的例字。《汉字例说》一文,作者从转注的角度综合考虑,对部分现代常用字作了分析,跟传统的解释有所不同。希望能抛砖引玉,互相切磋,以推进学术研究。 相似文献
13.
《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
15.
Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
18.
Rachel Zupek 《海外英语》2007,(11):40-41
我们绝大部分人都同意一件事情——我们喜欢金钱。但是你对金钱的喜欢之情足够到让你创立一份事业么?.财富通常被人忽视,主要在于人们不能真正了 相似文献
19.
YANGShiguo 《重庆大学学报(英文版)》2004,3(1):86-88
The problem on the geometrc inequalities involving an n-dimensional simplex and its inscribed simplex is studied. Aninequality is established, which reveals that the difference between the squared circumradius of the n-dimensional simplex andthe squared distance between its circumcenter and barycenter times the squared circumradius of its inscribed simplex is not lessthan the 2(n-1)th power of n times its squared inradius, and is equal to when the simplex is regular and its inscribed siplex is atangent point one. Deduction from this inequality reaches a generalization of n-dimensional Euler inequality indicating that thecircumradius of the simplex is not less than the n-fold inradius. Another inequality is derived to present the relationship betweenthe circumradius of the n-dimensional simplex and the circumradius and inradius of its pedal simplex. 相似文献
20.
Rajesh Kanoi 《海外英语》2007,(1):52
Today, Sunday morning, I sit thinking and typing at my computer. My thoughts are in my homeland, India and my body is in China. The body is here and mind there for a good reason. Mr. Hu is president and I am resident and both are in each other's countries (what a difference the absence of one small letter makes!). Mr. Hu will return in a few days and I will stay on longer. 相似文献