共查询到20条相似文献，搜索用时 109 毫秒
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提出了利用二甲酚橙为显色剂测定电镀液中微量钞的一阶导数分光光度法．根据在６２４ｕｍ处的导数值测定钐的含量．本方法简单、快速、方便、准确，可用于电镀液中微量钐的测定．相对标准偏差小于３％，回收率为９７．４％～１０１．８％． 相似文献
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文章研究了利用导数吸光光度法测定混合稀土钐钆富集物中微量的钐、铕、钆,提出了分离钐、钆的最佳条件,并经试样分析验证,结果良好。 相似文献
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用C1-P507淋树脂分析测定钐铕钆中各元素含量的方法,快速,价廉。可应用于稀土分组分离的中间控制和产品自检,本文研究了淋洗酸度、温度、流动相流速及料液中其它稀土元素含量对分析计价元素铕的影响。 相似文献
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研究了二碘化钐和异氰酸苯酯的反应，分离获得了二碘化钐被氧化的产物，并经元素分析，红外光谱和Ｘ光单晶衍射分析表征。二碘化钐和异硫氰酸苯酯、二硫化碳、二氧化碳反应，也均得到同样的钐络合物。 相似文献
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研究了用铈量法测定铜氨络合物中Cu含量的方法，确立了最佳测定条件．该法操作简便、快捷，结果准确可靠．可于生产过程快速仲裁分析． 相似文献
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研究了用碘一淀粉体系分光光度法测定海带中微量碘含量的方法，探讨了最佳测定条件．实验证明，该法具有准确度高，重现性好，简便快速的特点是测定海藻类中微量碘的一种较好方法． 相似文献
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超临界流体色谱快速测定烟酰胺的含量 总被引：1，自引：0，他引：1
采用超临界流体色谱快速测定制剂中烟酰胺的含量．在CO2流动相中添加10％的甲醇，于填充柱上分离，检测波长为216nm．在测定范围内，浓度与其峰面积呈良好的线性关系(r=0．9998)，峰面积的相对平均偏差(RSD)为1．39％，平均回收率97．3％～101．3％，4min即可完成分析．方法简便，样品前处理简单，可用于制剂中烟酰胺的快速分析． 相似文献
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非水滴定法测定香烟中尼古丁 总被引：1，自引：0，他引：1
在Ba(OH)2用下，用甲苯一氯仿9：1（V/V)混舍液萃取香烟中尼古丁．过滤、干燥处理后用高氯酸-冰醋酸标准溶液进行非水滴定，测定烟草中尼古丁含量．方法简便、快速，不使用标准品、应用于香烟中尼古丁含量的测定．相对标准偏差小于3.91％，加标回收率在96．8％～102．6％之间． 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