共查询到20条相似文献，搜索用时 125 毫秒
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从天然易得的顺一12-二十二碳烯酸(芥酸)出发,经臭氧化硼氢化钠(硼氢化钾)还原合成相应的13-羟基十三碳酸,随后经乙酰化得13-乙酰氧基十三碳酸,再经溴代脱羧反应得12-乙酰氧基溴代十三碳烷,最后与三苯基磷反应,接着在NaH-DMSO条件下,与乙醛进行维悌希反应合成了亚洲玉米螟信息素,即顺、反-12-十四碳烯醇醋酸酵,本合成路线中的各中间体化合物及最后产品均用红外光谱,核磁共振谱分析证实。 相似文献
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以3β-羟基孕甾-5-烯-20-酮-3-醋酸酯为起始原料,经溴仿、酯化、氧化、还原、胺化等反应,得中间产物N-叔丁基-3-羰基-4-氮杂-5-雄甾-17β-甲酰胺,再经碘代反应和脱碘反应脱去1、2位氢合成非那甾胺. 相似文献
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苯乙酸乙酯与金属钠反应所生成的碳负离子与碳酸二乙酯反应生成苯基丙二酸二乙酯,经四氢化铝锂还原、酸化得到2-苯基-1,3-丙二醇.通过四溴化碳/三苯基膦、硫代乙酸钾的羟基官能团转化反应,合成2-苯基-1,3-二溴丙烷和2-苯基-1,3-丙二硫醇乙酸酯,最后用肼还原硫醇乙酸酯,合成了目标产物2-苯基-1,3-丙二硫醇.所有中间产物和目标产物经核磁共振氢谱或红处光谱表征. 相似文献
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研究以天然β-蒎烯为原料经化学合成制得紫苏醛。采用乙腈为介质,以氯化亚铜-苯甲酸铜为催化剂,β-蒎烯与过氧化苯甲酰在65±2℃反应16h,得到的紫苏醋酸酯进一步水解、水汽蒸馏得粗品,减压精馏得纯度为96%的紫苏醇,收率为73%;紫苏醇在二氯乙烷中,用K2S2O8-NaOH-H2O,在40℃催化氧化反应9h,经酸化、静置分层、水洗、干燥、回收溶剂后得紫苏醛,GC分析含量91.2%,收率85.5%。合成紫苏醛的总收率62%(以-β蒎烯计)。经分析测试证明产物与文献报道值相符。 相似文献
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对松叶蜂 diprion pini性信息素活性组分 3,7-二甲基 -2 -十三碳醇乙酸酯的全合成进行了研究 .以丙二酸二乙酯和 2 ,3-环氧丁烷为原料 ,分别合成了两个重要结构单元—— 2 -甲基 -1-辛烷基锂和 3,4-二甲基 -γ-丁内酯 .2 -甲基 -1-辛烷基锂与 3,4-二甲基 -γ-丁内酯反应 ,得到的酮醇再经黄鸣龙还原 ,得到 3,7-二甲基 -2 -十三碳醇 ,经酯化 ,得到 3,7-二甲基 -2 -十三碳醇乙酸酯 相似文献
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α-溴代富马酸二甲酯（α—BrDMF）的合成分为两步：以冰乙酸为溶剂,富马酸二甲酯（DMF）与溴发生亲电加成反应生成富马酸二甲酯二溴化物（α—BrDMF）;d—BrDMF与氢氧化钠的乙醇溶液共热,发生消除反应可得α—BrDMF。在单因素实验的基础上通过正交实验对反应条件进行了优化,得到最佳反应条件。加成反应最佳工艺条件为：当DMF与溴的摩尔比为1：1．1,在4℃下反应10h,产率为70．6％。消除反应最佳工艺条件为：反应物料摩尔比为1：1,在60℃下反应2．5h,可得灰白色固体α—BrDMF。皮肤过敏性测试表明α—BrDMF无明显致敏性。 相似文献
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利用顶空固相微萃取技术（SPME）吸附樟树叶的挥发性物质,采用GC／MS技术分析鉴定,用峰面积归一化法进行定量。从樟树叶中鉴定出38种化学物质,占挥发性物质总量的98．53％。樟树叶的主要挥发性物质有石竹烯,（Z,Z,Z）-1,5,9,9-四甲基-1,4,7环-十一碳三烯,己酸叶醇酯,S-（Z）-3,7,11-三甲基-1,6,10-十二烷三烯-3-醇,3,7-二氢-3-甲基1H-嘌呤-2,6-二酮等。 相似文献
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采用同时蒸馏萃取方法对松乳菇挥发性成分进行提取,并用气相色谱—质谱法对提取物进行化学成分分析.从同时蒸馏萃取提取物中鉴定出了67个成分,并以归一化法测定了各个成分的质量分数.其中超过2%的有9种：1-辛烯-3-醇（2.27%）,丁酸丁酯（13.52%）,（E）-2-辛烯醛（2.88%）,n-癸酸（4.99%）,[1 aR-（1 a..α,4..β,4 a..β,7..β,7 a..β,7b..α）]-十氢-1,1,4,7-四甲基-1H-环丙烯并[e]薁（4.16%）,n-十六烷酸（4.75%）,（Z）-9,17-十八碳二烯醛（5.19%）,（E）-9-十八碳烯酸（3.33%）,十八烷酸（2.13%）. 相似文献
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<正> 由卤代烷与巯基乙酸反应制备烷硫基乙酸,已有文献报道。但反应都是在甲醇溶剂中进行的。本文用三缩四乙二醇<分子量=194.23)作为相转移催化剂,在50％NaOH水溶液中,用自制的α—乙基溴代已烷与巯基乙酸反应,合成α—乙基己硫基乙酸,产物为无色透明液体,b·p/4mmHg为145°—147℃,产:率为71％。α—乙基己硫基乙酸及其酯类,对稀有金属离子具有良好的萃取性能,是一类新型的复合官能困萃取剂。 其合成反应方程式如下: 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