共查询到20条相似文献，搜索用时 106 毫秒
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新制大环四胺与酚类物质可形成Zn（Ⅱ）配合物。6-（2'-羟基）-苄基1、4、8、11-四氮杂环十四烷（LA）和6-（2'-羟基-5'-溴）-苄基1、4、8、11-四氮杂环十四烷（LB）和 6-（2'-羟基-3'、5'-二溴）-苄基1、4、8、11-四氮杂环十四烷（Lc）确定可作为4-硝基苯酚乙酸盐（NA）的水解催化剂,pH=5时,含酚环与ZnL1:1配合,在 10％CH3CN溶液中,298K=0.10mol/dm3KNO3和pH=7.0-9.5时,对 Zn（Ⅱ）配合物进行动力学研究表明,配位酚是一种好的亲核试剂,对NA的水解有良好的催化性能,水解速率遵循方程式V=（Kcat[配合物] KoH[OH] K0）[NA]。 相似文献
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用分光光度法研究了酚侧基功能化新型大环四胺Zn(Ⅱ)配合物作为对硝基苯酚乙酸脂(NA)水解的催化剂,通过对其水解动力学的研究,结果表明水解速率遵循速率方程,催化反应受酸碱平衡控制,催化机理与天然酶一致,显示了本研究设计的配体和Zn酶中配为环境相似的特点,证实配位酚基可以作为一种好的亲核试剂有效地催化对硝基苯酚乙酸脂(NA)的水解. 相似文献
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本文报道了一个两亲性双功能臂大环多胺化合物的合成,并研究了它的配合物对α－氨基酸酯的催化水解性能。结果表明,它的二价过渡金属离子（如Cu2+,Co2+,Mn2+,Ni2+,Zn2+）配合物能显著的加速催化α－氨基酸对硝基酚酯的水解。 相似文献
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相海鹰 《连云港师范高等专科学校学报》2008,(3)
合成了过渡金属元素锌与三（3-氨基丙基）胺的配合物,并通过元素分析、红外光谱等表征;通过X-衍射测定了配合物的晶体结构。配合物属于立方晶系,空间群为P-43m,配合物中金属离子Zn^2＋处于4个N原子的配位环境,形成扭曲的四面体构型。 相似文献
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合成了[Cu2（Phen）4L]（ClO4）3*xNaClO4三个咪唑类配体桥连双核铜配合物（L分别为苯并咪唑,吡唑,4（5）-甲基咪唑负离子）并用元素分析,红外光谱进行了表征,测定了配合物的ESR谱和电化学伏安特性,用核黄素光照法测定了25℃时配合物催化超氧离子歧化反应的速度常数,所有配合物均有SOD活性。 相似文献
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相海鹰 《连云港师范高等专科学校学报》2008,25(3)
合成了过渡金属元素锌与三(3-氨基丙基)胺的配合物,并通过元素分析、红外光谱等表征;通过X-衍射测定了配合物的晶体结构.配合物属于立方晶系,空间群为P-43m,配合物中金属离子Zn2+处于4个N原子的配位环境,形成扭曲的四面体构型. 相似文献
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合成了N-正丁基二乙醇胺和长链N-十二烷基二乙醇胺两种配体，在30℃和pH7．20的条件下，研究了这些配体与Ce(Ⅲ)形成的金属配合物对双(对硝基苯酚)磷酸酯(BNPP)的催化水解作用，实验发现，这些金属配合物对BNPP有高效快速的催化水解作用，由长链N-十二烷基二乙醇胺-Ce(Ⅲ)形成的多核功能金属胶束对BNPP的水解作用大于短链的N-正丁基二乙醇胺-Ce(Ⅲ)金属配合物。在pH7．2时，其水解的表观一级速率常数分别为8.77x10^-3s^-1和1．62x10^-2s-1，为BNPP自发水解的10^8和10^9倍，接近于天然酶的活性水平。提出了催化反应的机理，建立了金属胶束和金属配合物催化通用的三元复合物动力学模型，获得了相关的热力学和动力学参数。 相似文献
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选择简单的小分子二乙醇胺(DEA)作为配体,与稀土Ce(Ⅲ)离子进行反应,成功地制备了稳定的DEA-Ce(Ⅲ)配合物,并用其作为模拟金属水解酶催化双(对硝基苯酚)磷酸酯(BNPP)的水解反应.利用紫外-可见分光光度法研究DEACe(Ⅲ)催化水解BNPP的动力学,探讨了pH和温度对BNPP水解反应的影响.结果表明,DEA-Ce(Ⅲ)配合物能够稳定存在,对BNPP的水解具有显著地催化促进作用 在pH 8.5时催化速率最大,且催化速率随着温度的增加而增加.在25℃和pH 8.5的条件下,DEA-Ce(Ⅲ)配合物对BNPP的水解表观一级速率常数为1.25 ×10-2s-1,是BNPP自发水解的1.14×109倍,通过阿伦尼乌斯公式计算得出该条件下催化水解反应的活化能为57.381 kJ/mol.最后提出了配合物催化BNPP水解的可能机理. 相似文献
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以N,N＇-二四唑胺（H2bta）为配体,合成了未见报道的碱土金属Ca、Sr的含能配合物,并对其进行基础的物化表征。化学分析、元素分析确定配合物的组成为Ca（bta）（H2O）5（1）和Sr（bta）（H2O）5（2）。溶解性实验表明,常温下配合物难溶于水,加热时溶解,不溶于常见的如甲醇,乙腈等有机溶剂。红外光谱分析表明,配体bta2-中N原子参与了配位。热重结果显示,在N2气氛、研究温度范围内配合物都有三个热分解过程,最终分解产物分别为以CaO与SrO为主的残余物。 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 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
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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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陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 相似文献
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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
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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