共查询到20条相似文献，搜索用时 62 毫秒
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李佩欣 《中学生数理化(高中版)》2008,(12)
问题35.在彩色电视机的显像管中,从电子枪射出的电子在2×10~4V的高压下被加速,形成1mA的平均电流.求: (1)每秒轰击荧光屏的电子数目; (2)电子轰击荧光屏所消耗的功率; 相似文献
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赵彩梅 《中学物理教学参考》2009,(8):39-39
在现代物理学研究中,为了探索原子核的内部结构及其性质,需要用能量很高的带电粒子去轰击各种原子核．为了大量产生高能带电粒子,需要用到加速器． 相似文献
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在现代物理学中,人们要用能量很高的带电粒子去轰击各种原子核.观察它们的变化情况.怎样才能在实验室中产生大量高能量的带电粒子呢?这就要用一种新的实验设备加速器.加速器涉及到的知识点比较多.既用到运动学知识.又用到能量知识;既涉及电场,又涉及磁场.可以很好地考查学生的各种能力,困此在高考中经常出现,在今年高考(江苏卷)中考查了串列加速器.加速器的种类很多,下面我们谈一谈常见的 相似文献
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慧生 《初中生学习指导(初三版)》2010,(12):30-31
1988年,我国第一台高能物理实验装置——北京正负电子对撞机在中国科学院高能物理研究所建成。它是一种先进的粒子加速器,将各种粒子（如质子、电子等）加速到极高的能量,然后用粒子轰击一固定靶,把靶打碎。通过研究高能粒子和靶中粒子碰撞时产生的各种物理反应,发现新现象,研究粒子的性质和构成。 相似文献
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陈宏 《中学物理教学参考》2002,31(6):58-60
在电子技术和核物理研究中 ,常常要用高速粒子去轰击研究对象——靶 .怎样才能在实验室大量产生高能量的带电粒子呢 ?这就要用到加速粒子的装置——加速器 .而加速器的种类较多 ,根据不同的需要可选择不同的加速装置 .本文分别对各种加速器的原理、用途作一简要介绍 ,并结合实例谈谈以加速器为背景而编制的试题的解法 ,仅供参考 .1.高压电源加速器早期制成的加速器就是用高压电源的电势差来加速带电粒子的 .这种类型的加速器受到实际所能达到的电势差的限制 ,粒子获得的能量并不太高 ,只能达到几万电子伏左右 .这种加速器主要用于示波器和显… 相似文献
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电子轰击存贮型脉冲离子源是为高分辨率、高灵敏度飞行时间质谱仪设计的新型离子源．它具有存贮以及时间压缩等特点，使仪器的整体性能有很大提高，质量分辨率达３５００．本文推导了二阶时间压缩聚焦条件，论证了存贮性能，给出了计算机模拟及实验结果． 相似文献
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沈玉芳 《中学化学教学参考》1994,(5)
近几年来,在奥林匹克竞赛中发展出一种新型试题——信息给予题(即构成题),并逐步渗透到高考化学试题中,这种试题能较好地考查各种能力,在有机试题中是渗透的重点,试看下面例题。 1.在高真空下,用高能电子束轰击一种气态分子时,分子中的一个电子可以被打击出去生成阳离子自由基,如苯甲酸: 相似文献
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华兴恒 《青苹果(高中版)》2014,(1):42-43
正发现、研究新的基本粒子,探索微观结构的极限,其使用的基本工具,就是复杂、神秘而又昂贵的人工粒子源——加速器。高能加速器担负的任务是把带电粒子(质子、离子、电子)加速到一定的能量,作为"探针"供各种不同的实验使用。通常研究的客体越小,"探针"的能量必须越高。现代高能加速器已能够获得密度为每秒钟1018个粒子的束流,于是可以开展大量的、有目的的实验研究,并应用到医学、现代工业等方面。1932年,英国科学家科克劳夫与沃顿建造了一台高压加速器,把质子加速到具有70万电子伏(1电子伏=1.6×10-19焦耳)的动能,并在历史上首次使用人工加速的粒子实现了核 相似文献
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结合有关文献资料,总结了颗粒自由沉淀试验的取样方法和数据处理方法.通过对文献中数据处理错例的分析,指出了在颗粒自由沉淀试验中,取样方法不同则颗粒浓度的意义不同,去除率的含义也不同;数据处理方法要根据取样方法合理选择. 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