4-烷基苯甲酸-1,4-苯二酚酯类液晶的合成与液晶相研究

以1,4-苯二酚和4-甲基、4-正丙基取代的苯甲酸为原料,通过室温氯化、酯化的方法,合成了二个4-烷基苯甲酸苯二酚酯液晶。产物结构经元素分析I、R及MS得到确认,化合物的液晶相通过DSC及POM(偏光显微镜)确定。结果表明这类化合物具有热致液晶性,呈典型的向列项纹影织构。     

一种新的脯氨酸衍生物类手性催化剂的合成

以脯氨酸为原料合成的一系列有机小分子化合物,在催化丙酮和苯甲醛的不对称反应中催化作用明显.而以L-脯氨酸为原料,通过氨基保护、羧基酯化、格氏反应、去保护4步反应,得到手性催化剂4步的总产率为43%.其结构经HNMR确证.     

萘二酚酯香蕉型及棒状液晶的合成与液晶性

以2,7-萘二酚,1,5-萘二酚和对甲基苯甲酸,对丙基苯甲酸以及对乙基环己基甲酸为原料,合成了4个萘二酚酯类液晶化合物,其中3个为香蕉型分子,1个为棒状分子。产物通过红外光谱仪、气-质联用仪(GC-MS)、紫外-可见分光光度计进行结构表征,采用示差扫描量热仪(DSC)及偏光显微镜(POM)研究了化合物的液晶行为。结果表明,所合成的这类萘环衍生物具有液晶的性质。     

单酯基芳香醛及芳香腈类液晶的合成与液晶相研究

以对羟基苯甲醛、对羟基苯腈,与4-正丙基苯甲酸、4-正丙基联苯甲酸为主要原料,通过氯化、酯化等方法,合成了四个多环单酯基类液晶：4-正丙基苯甲酸-4′-氰基苯酚酯,4-正丙基苯甲酸-4′-醛基苯酚酯,4-（4-（4-正丙基联苯）酰氧基）苯甲醛,4-4-（4-（4-正丙基联苯）酰氧基）苯腈。产物结构经元素分析、IR及MS表征,化合物的液晶相通过DSC及POM（偏光显微镜）确定。结果表明其中2个化合物具有热致液晶性,呈典型的向列项纹影织构。     

一种偶氮苯甲醛液晶化合物的合成及性质

合成了一种既有液晶性又有光敏性的多功能化合物4-[4-(4-丙基苯酰氧)苯偶氮]苯甲醛,运用差热扫描量热分析（DSC）、偏光显微技术（POM）研究了化合物的液晶相性质,运用紫外光谱分析法研究了其紫外光照射后的光反顺异构化过程。结果显示,该化合物具有典型的液晶相性质,且液晶相温度范围宽;同时,该化合物能够发生光致反-顺异构化反应,在甲醇或者THF溶液中反-顺光异构反应为一级速率过程。     

多羟基树状化合物的合成及增溶性研究

以端基为丙烯酸酯双键的树状化合物[PAE(=)8]分别和二乙醇胺(DEA)、三羟甲基氨基甲烷(Tris)为原料,合成了端基为16和24个羟基的树状化合物.测定了多羟基树状化合物的表面张力及对苯甲酸、水杨酸、甲基红的增溶性.实验结果表明,端基为16个羟基的树状化合物[PAE(OH)16]具有较强的表面活性,而端基为24个羟基的树状化合物[PAE(OH)24]不具有表面活性.对比PAE(OH)16PAE(OH)24和十二烷基硫酸钠(SDS)对苯甲酸、水杨酸及甲基红等难溶客体分子的增溶性,得出增溶能力大小顺序为:PAE(OH)24>PAE(OH)16>SDS.     

光致变色液晶化合物的应用及其研究进展

介绍了光致变色液晶化合物的分类及光致变色液晶高分子在信息存储领域的应用.综述了光致变色液晶小分子化合物研究进展及其应用前景.总结了光致变色液晶材料光调控的方式.     

树枝状化合物聚氨酯-胺的合成及表征

通过逐步聚合方法,以均苯三甲酸为起始原料(作为中心核),通过与甲醇发生酯化反应生成酯,再与乙二胺发生取代反应,之后先于H12MDI反应构建活性中间体,再与三乙醇胺反应,合成了G0～G3.0代树枝状化合物.通过红外光谱对其官能团进行归属,利用扫描电镜观察微观形貌,判断孔径大小;利用热重分析对其热学性质了解;最后用茶碱的缓...     

3-(2,4-二氯苯基)丙酸1H-1,2,4-三唑基甲醇酯的制备与结构表征

以1H-1,2,4-三唑和3-(2,4-二氯苯基)丙酸为起始原料,经过缩合、氯化和酯化等反应,合成了标题化合物3-(2,4-二氯苯基)丙酸1H-1,2,4-三唑基甲醇酯。用甲醇作为溶剂重结晶,得到了标题化合物的单晶,并且通过IR、1H NMR和X-射线衍射等方法确证了其结构。     

没食子酸改性魔芋葡甘露聚糖的新方法

为提高魔芋葡甘露聚糖的性质以及应用范围,采用了在1-乙基-(3-二甲基氨基丙基)碳二亚胺盐酸盐(EDC)和4-二甲氨基吡啶(DMAP)催化下,使三乙酰没食子酸(TAGA)与葡甘露聚糖进行酯化改性,并用红外测定了其结构特征,同时研究了其粘度及成膜性。当三乙酰没食子酸与葡甘露聚糖的质量比为1:2,三乙酰没食子酸与EDC的物质的量比为1:1.5时粘度及成膜性最佳,为魔芋葡甘露聚糖的改性研究提供了新方法。     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

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?     

只要努力,不要后悔

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.     

浅谈移民问题

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.     

Sister Carrie, an Adherent of Desires

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.     

Improvement of one-cycle controller by use of proportional integral differential controller

1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec…     

库克斯顿城堡

城堡, 是欧洲典型的建筑之一, 每个城堡都有一个美丽的传说或是一段历史。从本期开始, 我们将推出“城堡之旅”, 带各位读者去浏览、观赏欧洲各地的城堡, 开始一段文化与历史的旅途!     

胡主席在印度,我却在中国

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.