二维统计中几个问题的分析

本文讨论了二维光子气体和自由电子气体的统计性质     

量子费米气体的热力学性质

金属的自由电子气是一种典型的量子费米气体.无论在n维空间中还是在极端相对论情况下自由电子对热容量的贡献都有如下规律:自由电子的热容量对金属热容量的影响在常温下可忽略,在T→0时却不可忽略.     

气体放电种种

在一般情况下,气体中的自由电子和正负离子等自由电荷的数目极少,所以气体是良好的绝缘体.但是,当空气中的分子发生电离而使气体导电时,就会出现种类繁多的"气体放电"现象.     

金属中自由电子气能量的研究

本文根据费米气体模型理论,研究金属中自由电子气的能量,讨论电子的最高能量、平均能量和电子气的能级密度.     

空气负离子与空气质量

1 空气负离子的形成 中性的空气分子在某种外力(电场、碰撞、辐射等)作用下,有些外层电子会脱离原子核的束缚,成为自由电子.自由电子很快就会附着在气体分子或原子上,而且特别容易附着在氧分子或水分子上,成为空气负离子(也叫阴离子).     

极低温度下金属中的自由电子对热容量的影响

在极低温度下,金属中自由电子的热容量不能忽略,考虑到自由电子气体应当遵从量子统计的费米分布,温度为T时处在能量为ε的一个量子态上的平均电子数为f=1/((ε-μ/ekT) 1)且我们知道在体积V内,在ε-ε dε的能量范围内自由电子可能的状态数为D(ε)dε=4πV/h3(2 m)3/2ε1/2dε,所以在体     

原子反弹激光中的光放大

本文引入了一种介于普通激光和自由电子激光之间的光放大机制,然后对其进行数值模拟,揭示了光放大的本质,并讨论原子密度、气体介质体积等工作参数对光放大的影响,对原子反弹激光有很好的指导意义。     

自由电子在强激光场中的运动

在强激光场中,自由电子的运动主要由激光场来支配,我们可以把自由电子看成经典的自由电子,把自由电子的运动看作完全经典的振动,用经典的方法来描述自由电子的运动图像.通过求解经典牛顿运动方程,求出自由电子运动速度的最大值,以求出相应的最大动能.     

自由电子激光器的新进展

本文对自由电子激光器的工作原理、实验装置以及自由电子激光辐射的基本特征等进行了详细介绍,在系统综述自由电子激光器的发展动态的基础上,指出了这一研究领域的发展趋势．     

漫谈空气负离子

空气是由多种分子组成的混合物,其主要成分是氮气和氧气．在正常情况下,气体分子是呈中性的,然而在自然界宇宙射线、紫外线、雷电、风浪、镭和钍等放射性物质作用下,空气中性分子因电离而释放电子,这些自由电子与空气中的一些分子结合就形成了空气负离子．而通常人们...     

卡思卡特城堡

It is worthy of noting that, whilst Crookston Castle witnessed the earlier and happier portion of Mary's variegated life,     

不同的吃喝玩乐

一、吃和喝吃苹果 eat an apple, 吃药 take medicine,吃糖 have some sweets,吃饭 have one's meals,吃馆子 dine out,吃惊 be surprised/     

漏洞百出的教育

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?     

Western and Eastern culture differences in commercial field

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.     

只要努力,不要后悔

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.     

浅谈移民问题

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.     

风的曲线

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.     

团图为数的图中的闭团贯数

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.     

Sister Carrie, an Adherent of Desires

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.