共查询到20条相似文献，搜索用时 62 毫秒
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王福民 《渭南师范学院学报》2003,18(5):28-31
桥联配合物是从化学键的角度通过桥配体结合起来的化合物．多核配合物是从原子数目上讲含有多个金属原子的化合物，从概念上讲二者略有不同，不能将他们混为一谈．文章讨论了二者的联系与区别，提出了桥联配合物的定义、命名，并研究了主族元素桥联配合物的结构与功能和在周期表中形成的倾向性。 相似文献
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首次以L-丝氨酸为桥联剂制备了新型稀土有机配合物一无机基质杂化材料,LnL3Phen／（SiO2）n,其中Ln=Eu,Tb;L=2-苄酰胺基-3-羟基丙酸;Phen=4~菲罗啉．通过核磁共振、紫外和荧光光谱对配体和杂化材料的结构和性质进行了表征．紫外光谱结果表明杂化材料呈现了结构中生色团的特征峰,荧光研究表明,杂化材料均呈现稀土离子的特征光． 相似文献
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以D,L-丙氨酸（D,L-Alanine）和对苯二甲酸（Terephthalic acid）为有机配体,与硝酸锌在水热条件下反应得到了金属-有机超分子聚合物[Zn5（D,L-Alaninato）4（Terephthalate）3]n（1）.在该化合物中,Zn（Ⅱ）离子与对苯二甲酸相互作用形成了二维的金属-有机配位层状框架,丙氨酸桥联Zn（II）离子形成了一维的配位链状结构.配位层与配位链之间通过氨基酸的桥联作用连接在一起形成了三维的超分子框架结构. 相似文献
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标题化合物是双齿配体4,4＇-联吡啶与碘化汞在甲醇和四氢呋喃混合溶液中反应得到的无色晶体。用X-射线测定了其单晶结构,该晶体属单斜晶系,Cc空间群。结构分析表明,汞离子与两个碘离子和来自4,4＇-联吡啶的两个氮原子配位形成畸变四面体构型,并且通过4,4＇-联吡啶桥联汞离子沿着c轴延伸构筑成一维“之”字型聚合物。 相似文献
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配位聚合物通常是指以金属离子或金属簇为中心,以有机配体为联结体,通过金属离子与有机配体之间的配位作用而形成的具有周期性网络结构的一类化合物.为了能得到结构新颖、功能独特的晶体材料,一些非常规的合成方法诸如原位合成法被发现和采用,本论文着重综述了配位聚合物的原位合成策略. 相似文献
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对苯二甲酸根桥联双核铜(Ⅱ)配合物的合成 总被引：5，自引：0，他引：5
在水溶液中以对苯二甲酸根(TPHA)为桥联配体,端接1,10-邻菲罗啉(phen)合成了一个新的三元混配的配合物[Cu2(TPHA)(phen)4].2ClO4,经元素分析以及红外光谱等手段,推定该配合物具有TPHA桥联双核铜(Ⅱ)结构,铜(Ⅱ)离子处于五配位的四角锥环境. 相似文献
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介绍了桥联茂金属催化剂的发展、分类以及它的高立体选择性、高定向性等性能。讨论了桥联茂金属催化剂以及对相关产物立构规整性的影响,并对其应用前景做出展望。 相似文献
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介绍了桥联茂金属催化剂的发展、分类以及它的高立体选择性、高定向性等性能。讨论了桥联茂金属催化剂以及对相关产物立构规整性的影响,并对其应用前景做出展望。 相似文献
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沈文中 《湖州职业技术学院学报》2013,(4):1-3,32
桥联是指桥上的对联,镌刻在石桥桥孔两侧石柱外侧的醒目位置,可供桥下行舟之人观赏。通过对湖州现存古代石桥的考察,笔者发现,桥联的大量出现是在清代乾隆以后,其内容大多为描写景物、劝人向善、记述造桥功德、指明地理位置等。桥联体现了一个时代的中国文学、书法艺术、建筑技术水平,是中国古桥文化的重要内容。 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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《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
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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
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唐芳 《读与写:教育教学刊》2008,5(6)
During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context. 相似文献