共查询到20条相似文献，搜索用时 65 毫秒
1.
王剑 《内江师范学院学报》2010,25(8):35-36
讨论了不同偏振态下的强激光与等离子体相互作用时的质子加速能谱,在激光强度是相对论性质时,质子加速过程以无碰撞激波加速为主,质子能谱在S偏振和P偏振基本一致。 相似文献
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阿不都热苏力 《喀什师范学院学报》2006,27(3):31-33
用二维粒子模拟方法研究了超强超短脉冲激光与三角凹形等离子体薄靶相互作用中产生的高能离子.模拟研究结果表明,在三角凹形等离子体薄靶后表面所产生的高能离子,角分布较小,定向性好,能获得很高的能量,并且等离子体薄靶的形状对高能离子的产生和会聚有一定的影响. 相似文献
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用超粒子模拟方法（Particle in Cell Method）数值研究了超强激光（10^20W/cm^2）与等离子体相互作用后产生的粒子束收缩问题.结果表明,由于超强激光照射的等离子体靶形的改变,直接影响被加速的粒子束收缩.阐述了激光辐照三角形壳靶时,等离子体向心会聚过程的数值模拟实验结果. 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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采用超短超强激光与固体靶相互作用实验和数值模拟研究了超热电子的角分布和能谱，结果显示：绝大部分超热电子沿着靶法线方向附近发射；激光入射角为20°时等离子体对激光的吸收达到最强；由超热电子能谱拟合的有效温度与共振吸收超热电子的温度定标律一致.这说明在预等离子体密度标长较大的情况下对电子加速起主要作用的物理机制是共振吸收机制. 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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乔红贞 《商丘师范学院学报》2013,(3):40-42
利用Nd:YAG脉冲激光诱导金属Cu靶,在空气中产生激光等离子体羽,获得了Cu等离子体羽的空间光谱;研究了等离子体谱线结构;分析了离焦量为-2 mm时,不同空间位置处等离子体的空间演化规律;并讨论了等离子体光谱的产生机制. 相似文献
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李东升 《数理化学习(高中版)》2005,(13)
例1来自质子源的质子(初速度为零),经一加速电压为800kV的直线加速器加速,形成电流强度为1mA的细柱形质子流,已知质子电量e=1.6×10-19C,这束质子流每秒打在靶上的质子数__,假定分布在质子源到靶之间的加速电场是均匀的,在质子束中与质子源相距L和4L的两处,各取一段极短的相等长度的质子流,其中的质子数分别为n1和n2,则n1:n2=__. 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献
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Given a graph G,a subgraph C is called a clique of G if C is a complete subgraph of G maximal under inclusion and |C|≥2. A clique-transversal set S of G is a set of vertices of G such that S meets all cliques of G. The clique-transversal number, denoted as TC (G), is the minimum cardinality of a clique-transversal set in G. The clique-graph of G, denoted as K (G), is the graph obtained by taking the cliques of G as vertices, and two vertices are adjacent if and only if the corresponding cliques in G have nonempty intersection. Let F be a class of graphs G such that F={G|K(G) is a tree}. In this paper the graphs in F having independent clique-transversal sets are shown and thus TC (G)/|G|≤1/2 for all G ∈ F. 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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陈美曦 《山东教育学院学报》2008,23(2):103-107
Different nations have different social cultures, and the social culture of every nation is developing with the development of the nation, language is greatly influenced by social culture, which enables language to possess national and historical characteristics. Word is the smallest, independent, meaningful linguistic unit of language. It can well reflect the national and historical characteristics. From synchronic aspect, the social and cultural influence on word meaning is mainly embodied in conceptual and associative meanings of word. The incorrespondence of word meaning is a phenomenon that exists in both conceptual and associative meanings of word among different languages. From diachronic aspect, the development of social culture causes some changes of word meaning to some extent. Therefore, social culture plays a key role in vocabulary learning and mastery of a language. 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