共查询到20条相似文献，搜索用时 78 毫秒
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生物农药研究进展 总被引：5，自引：0，他引：5
刘刚毅 《邵阳学院学报(社会科学版)》2003,2(2):131-135
从生物农药的发展、内涵以及研究和利用进行探讨，并对生物农药的发展趋势作出了较深刻的分析。 相似文献
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分别以面部、楝果、辣蓼为主提取的植物农药对玉米螟防治效果明显，其中以辣蓼效果为最佳；而供试的5个玉米自交系之间的抗螟性差异显著。 相似文献
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应用生长速率法测定了桑寄生（Loranthus parasiticus）、菟丝子（Cuscuta chinenssis）和无根藤（Cassytha fuliformis）三种寄生性种子植物的丙酮提取物对立枯丝核茵（Rhizoctonia solani）、茄链格孢茵（Ahernaria solani）、腐皮镰刀茵（Fusarium solani）、玉米大斑凸脐蠕孢茵（Exserohilum turcicum）和香蕉炭疽菌（Gloeosporium musarum）的抑菌活性。结果显示三种植物都表现出一定的抑茵活性,其中桑寄生对所有供试菌种的抑菌活率茵均在50％以上;其次是无根藤,除对香蕉炭疽茵效果较差外,对其余4种病原菌的抑茵率均在40％以上;菟丝子则对立枯丝核茵、茄链格孢菌和香蕉炭疽菌表现出较好抑茵活性,其抑菌率在30％以上。 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