共查询到20条相似文献，搜索用时 62 毫秒
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为了开发特异性的蟑螂引诱剂,以饲养德国小蠊的废弃物为材料,以水、乙醇、丙酮作为提取溶剂,研究不同质量浓度的提取物对德国小蠊的引诱活性.结果表明:用乙醇、丙酮作为提取溶剂时提取物引诱到的德国小蠊数量高于用水作提取溶剂时提取物引诱到的虫数,且与CK差异显著,说明用乙醇和丙酮作为提取溶剂优于用水作为提取溶剂.在提取新鲜的废弃物时,对德国小蠊引诱活性最强的提取溶剂是乙醇,其最佳作用质量浓度为1 g/L;在提取干燥的废弃物时,对德国小蠊引诱活性最强的提取溶剂是丙酮,最佳作用质量浓度为10 g/L. 相似文献
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冬青叶叶绿素提取工艺研究 总被引：1，自引：0，他引：1
以冬青叶片叶绿素提取量为衡量指标,通过单因素实验确定提取剂、提取剂用量、提取温度以及提取时间,再利用正交实验,优化提取的工艺条件.结果表明,以丙酮、乙醇(体积比2:1)混合液为提取剂,提取时间24h,提取剂用量20 mL,提取温度60℃是提取冬青叶片叶绿素的最佳工艺条件. 相似文献
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许立 《淮南师范学院学报》2006,8(5):113-114
文章研究了地肤叶绿色素的最佳提取条件、基本性质及其稳定性。结果表明:以90%的乙醇为提取剂,料液比(g︰mL)在1︰50,于50～60℃下浸提24h效果最好。该色素易溶于丙酮、乙醇和碱溶液,对光、热、氧化剂、还原剂和大部分金属离子都比较稳定。 相似文献
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针对冀东地区常见的九种树木叶片及相应虫沙,对其叶绿素提取液的吸光度值及吸收光谱进行了对比研究。结果显示：鲜叶乙醇提取液在430nm和663nm有强吸收峰,虫沙乙醇提取液在410nm和663nm有强吸收峰。相同条件下,乙醇对于鲜叶片中叶绿素的提取效果优于丙酮;而丙酮对于各种虫沙中叶绿素的提取效果优于乙醇。 相似文献
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牡丹叶绿素的提取及其性质研究 总被引：11，自引：0，他引：11
以分光光度法首次研究了牡丹叶绿素的提取方法,用8种提取液在不同时间内优选最佳实验条件,测定了不同品种牡丹叶绿素含量及不同温度下各品种叶绿素的稳定性.结果表明:室温下,以丙酮:95%乙醇=2:1为提取液,浸取24h的方法最佳,不同品种牡丹叶绿素含量差别不大;叶绿素稳定性受温度的影响不大. 相似文献
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叶绿体中色素的提取和分离是高中学生必做实验。教材中列出了具体的实验步骤。但笔者在实验教学过程中,发现有以下几点需要改进。ａ.提取绿色叶片中的色素。教材认为在研钵中,加入少许二氧化硅和碳酸钙白色粉末,再加入2ｍＬ丙酮,进行迅速充分的研磨。笔者在实验教学过程中发现加入2ｍＬ乙醇(分析纯)比加入丙酮要好。一是乙醇比丙酮挥发慢些,二是乙醇的毒性比丙酮的毒性小得多。此时注意研磨一定要充分,色素才到滤液里。过滤提取滤液,注意滤液呈墨绿色。ｂ.制备滤纸条与划滤液线。教材中规定用定性滤纸剪成长10ｃｍ、宽1ｃｍ的滤纸条且将一端… 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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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,(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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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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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