共查询到20条相似文献，搜索用时 62 毫秒
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佘芹 《中小学实验与装备》2000,10(2):14
1 改进后的实验装置 可调节高度/H2O/电石/铁丝网/H2O/碱石灰/KmnO4(H+)/点燃/溴水 图1 2 实验操作 2.1 按上图所示连接实验装置,检查装置的气密性. 2.2 向各仪器里加入实验用药品. 相似文献
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在绿色化学思想指导下,将小量-半微量实验方法运用于无机元素性质实验,结合实验教学实际,探讨了P区元素中卤素、硫的含氧酸盐、硫化物和铅的难溶盐等性质实验的试剂用量.结果显示,小量-半微量实验的试剂用量可降至常规用量的1/2~1/6,可节约实验开支,提高实验效率,减少环境污染,有利于学生树立绿色化学理念,增强环保意识. 相似文献
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经NIH小鼠急性毒性实验测定结果表明,贡品健身酒最大耐受量为270ml/kg.贡品健身酒5,10,20ml/kg给动物灌胃,可降低小鼠脑、心、肝脂质过氧化产物丙二醛含量;10,20m1/kg剂量组,可增加小鼠血清溶血素含量,延长小鼠爬杆时间和负荷游泳时间,对戊巴比妥钠诱导的小鼠入睡时间可显著延长;对大鼠血清总胆固醇含量可显著降低.体外实验还证明贡品健身酒具抗肿瘤作用,实验结果提示。贡品健身酒具明显的保健功效. 相似文献
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试行有机合成实验微型化,试剂用量可减至常量的1/10,所用仪器规格要与试剂用量相对应.实践证明,此项改革还可减少环境污染,以及有利于培养学生规范化操作. 相似文献
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卫迎辉 《河北北方学院学报(社会科学版)》2000,(3)
为了满足《微机原理》教学的需要,增加一个D触发器使TPC-1实验系统可完成利用查询式方法采样数据的A/D转换实验,并介绍了利用虚写端口的操作改变D触发器状态的技术. 相似文献
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刘志伟 《学生之友(初中版)》2013,(Z1):8-10
[义务教育课程标准实验教科书八年级《数学》（人民教育出版社）下册]第61页第9题揭示了正比例函数与反比例函数交点坐标的规律.在同一直角坐标系中,正比例函数y=k1x与反比例函数y=k2/x没有交点,请确定两个常数的乘积k1k2的取值范围.分析:解答本题,既可从k1、k2的符号入 相似文献
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胡海俊 《中学物理教学参考》2012,(8):39-41
"半偏法"测电表内阻是高中电学部分测量电表内阻的重要方法之一.其综合性较强,也比较难理解,学生往往靠死记硬背实验原理及步骤,学习效果不尽如人意.那么,教学中怎样让学生主动学习和探究呢?笔者在实验教学中试图引导学生模仿探究学习,以提高学生的综合实验能力."半偏法"测电表内阻的实验电路如图1、图2所示.图1、图2两电路中电阻R1均不必读数,所以可选用变阻器、电位器或电阻箱;R2需要读数,所以必 相似文献
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王良 《咸阳师范学院学报》2005,20(4)
利用正交试验找到用SO2-4/TiO2-Fe2O3固体超强酸催化合成丁酸丁酯的最佳反应条件.即反应时间4.0h,催化剂用量为酸质量的1.4%,酸醇比1.2:1,验证实验产率为97.6%.且该实验反应时间相对短,无腐蚀无污染,催化剂可回收可重复使用. 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