共查询到20条相似文献，搜索用时 632 毫秒
1.
2.
3.
四氯化锡催化合成己酸异戊酯 总被引：1，自引：1，他引：1
研究了用四氯化锡催化己酸和异戊醇合成己酸异戊酯的反应。考察了酸醇摩尔比、催化剂用量、反应时间、带水剂用量等因素对酯化率的影响。优化反应条件为：催化剂用量0.5g／0．08mol己酸，酸醇摩尔比1．0：1．4，用6ml环己烷/0．08mol己酸为带水剂，反应时间120min，酯化率可达96.28％。 相似文献
4.
5.
钨硅酸催化合成乙酸辛酯 总被引：3，自引：2，他引：3
以钨硅酸为催化剂，通过乙酸和辛醇反应合成了乙酸辛酯。探讨了酸醇物质的量比、催化剂用量以及反应时间对酯化率的影响。实验结果表明：钨硅酸催化合成乙酸辛酯的最佳条件为：酸醇物质的量比1．3：1，催化剂用量0．2g／0．1mol(辛醇)，带水剂(环己烷)10mL，反应时间1h．温度100～118℃．在此条件下其酯化率可达99．30％。 相似文献
6.
以硫酸钛为催化剂，通过乳酸和异戊醇反应合成了乳酸异戊酯。探讨了催化剂用量、醇酸物质的量比以及反应时间对酯化率的影响。实验结果表明：最佳条件为：催化剂用量0．3g／0.1mol乳酸，醇酸物质的量比1．2：1，带水剂(环已烷)8mL，反应时间1．5h，温度80～105℃，在此条件下，酯化率可达98．38％。 相似文献
7.
固体超强酸S2O2-8/ZrO2-TiO2催化合成乙二酸二丁酯 总被引：5，自引：0，他引：5
制备固体超强酸催化剂S2O8^2-/ZrO2-TiO2用于合成乙二酸二丁酯，较系统地研究了该催化剂焙烧温度、用量、酸醇物质的量比、反应时间、反应温度和带水剂用量对酯化反应的影响．实验表明：S2O8^2-/ZrO2-TiO2是合成乙二酸二丁酯的良好催化剂．在催化剂焙烧温度为500℃，乙二酸为0．2mol时，酸醇的物质的量比为1：4，反应温度为130～135℃，反应时间为90min，催化剂用量为2．0g的优化条件下，乙二酸二丁酯的酯化率达95％． 相似文献
8.
杨树 《昆明师范高等专科学校学报》2001,23(4):67-69
利用硫酸氢钠作为酯化反应催化剂合成了己酸异戊酯，确定了其最佳反应条件为：催化剂用量为0．2g／0．1mol己酸，醇酸物质的量比为1．5：1，带水剂环己烷10mL，回流反应时间1．5h，己酸的酯化率可达99．39％。实验表明该催化剂催化效果好，使用量少，酯化率高，环境污染小，廉价易得，很有应用价值。 相似文献
9.
介绍了新型催化型TiSiW12O40/TiO2的制备方法，实验考察了以自制的该催化剂催化合成甲酸丁酯的酸醇化，催化剂用量，反应时间等因素对反应产率的影响，实验表明：在酸醇物质的量比为2．5：1，催化剂用量为反，反液的1．78％，酯化反应时间为40min，反应温度为94－98℃时，反应产率可达72．2％。 相似文献
10.
磷钨杂多酸催化合成丙酸丁酯 总被引：2，自引：0，他引：2
以磷钨杂多酸为催化剂，通过丙酸和丁醇反应合成丙酸丁酯，研究了各有关因素对丙酸酯化率的影响．实验证明，磷钨杂多酸是合成丙酸丁酯的良好催化剂．在酸醇物质的量比为1：1．2，催化剂用量1．0％（占反应物总质量的百分数），带水剂环己烷10mL／0．2mol丙酸，反应时间为80min，反应温度100～115℃的条件下，丙酸的酯化率可达99．3％． 相似文献
11.
12.
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
14.
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.
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
16.
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
17.
18.
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
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.