共查询到20条相似文献，搜索用时 532 毫秒
1.
赵自成 《雁北师范学院学报》2001,17(6):39-40
舒巴坦钠作为一种酶抑制剂,在目前的临床治疗中得到了广泛的应用,其含量测定方法在CP2000中使用C18色谱柱,流动相为0.05mol/L的氢氧化四丁基铵/乙腈(1650:350),检测波长:230nm,其中乙腈毒性非常大,且成本高,本文所建立的方法将氢氧化四丁基铵改为磷酸二氢钠,因氢氧化四丁基铵是强碱性化合物有很强的腐蚀性,而磷酸二氢钠无论从哪一个角度讲都较氢氧化四丁基铵温和且价格低廉.同时本法所用甲醇比例较原法乙腈少,这样既减少了毒性危害又降低了成本.本法精密度及线性关系良好,其平均回收率为99.8%.RSD为1.12%(n=5). 相似文献
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由四丁基氢氧化铵水溶液与氟铝酸铵反应制备了复合型离子液体四丁基铵的氟铝酸盐,采用1H-NMR、19F-NMR、MSI-MS、FTIR、Raman等对其结构进行了表征,并对其一些物理和电化学性质进行了研究.结果表明,该化合物热稳定性好,具有较高的电导率和较宽的电化学窗口,是一种很有潜力的电解质. 相似文献
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《南阳师范学院学报》2021,(3):25-30
一种特殊的芘基结构季铵化合物与多金属氧酸盐结合得到复合催化剂,该催化剂可在无溶剂条件下实现硫醚化合物的选择性催化氧化.该反应体系在室温下进行,使用过氧化氢为氧化剂,具有绿色、安全、高转化数的特点. 相似文献
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以2010年诺贝尔化学奖为背景,回顾了钯催化交叉偶联反应的发展历程,描述了钯催化交叉偶联反应的反应机理及实际应用,并对钯催化交叉偶联反应的最新进展做了展望。 相似文献
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报道了紫外光源在制备金属薄膜材料方面的应用研究,金属钯是一种优良的催化剂,首先在各种衬底上面淀积靶的金属有机化合物薄膜,通过紫外分解钯的金属有机化合物,形成数埃到几十埃的色膜,然后再利用钯的催化效应,在无电极电镀中淀积出几十纳米到几微米厚的各种金属薄膜（如Cu、Au、Ni等）。 相似文献
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以葡萄糖和叔丁基对苯二酚为原料,用AgOTfa／SnCl4作为催化体系,合成碳糖苷,再经硝酸铈铵氧化,高立体选择性合成了一种新型的醌基碳糖苷,并通过IR、UV、^1HNMR分析进行了化合物结构确证。 相似文献
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钯及其配合物催化剂在有机合成中具有广泛的应用.主要综述钯催化Heck反应近年来的最新进展,重点介绍了各种配体在钯催化Heck反应中的所起的作用. 相似文献
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以钛酸丁酯、四丁基氢氧化铵、硝酸铈为原料,采用溶胶一凝胶法合成C—Ce—TiO2光催化剂,经XRD、UV—Vis—DRS表征,在9W日光灯照射下光催化降解农药。结果表明：随着碳掺杂量的增加,微晶粒径减小、禁带能隙降低、对农药的光催化活性增大。 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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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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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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《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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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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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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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