12C+27Al深部非弹性散射研究

用△E-E 计数器望远镜鉴别反应产物,研究71.5兆电子伏的¹²C 离子在²⁷Al 靶子上的深部非弹性散射,得到了产物 B 和 Be 在质心系 E-θ平面的截面等高线图。由图可以看出准弹性散射和深部非弹性散射的一般特征。有两点值得特别指出:第一,从淮弹性峰到深部非弹性散射岭呈现某些精细结构.第二,完全阻尼部份的平均动能不等于终态库伦能.     

义务教育七年级数学研究性学习的一个案例

本案例依照北师大版义务教育课程标准实验教科书及其教学参考书 (七年级上册 )的指导思想进行设计和教学 ,文中的问题是以该教科书第 1 1 1页复习题C组第 3题为背景进行加工拓展而成的 ,特此说明 .1　学生作业单之一1 1　动手实践 :操作 1　用棋子摆出图 ( 1 )、( 2 )、( 3) ,数一数 :摆图 ( 1 )用个棋子 ,摆图 ( 2 )用个棋子 ,摆图 ( 3)用个棋子 .操作 2　按照上述方式摆出第 ( 4 )个图形和第 ( 5 )个图形 ,数一数 :摆图 ( 4 )用个棋子 ,摆图 ( 5 )用个棋子 .提示 :摆出第 ( 4 )、( 5 )个图形的方式是否唯一呢 ?1 2　自主探索 :问题 1　…     

GEOMETRIC AND ELECTRONIC STRUCTURES OF Ti8C12 CLUSTER

The electronic structure of Ti₈C₁₂ clusters with three possible geometric structures suggested in the literature is studied using the discrete-variational local-density-functional method. The results show that the ground states of the clusters are all degenerate, which means further Jahn-Teller distortions for the geometric structures of clusters. The results also indicate that the distorted dodecahedral Ti₈C₁₂ cluster, which is proposed by Guo et al. and optimized by the first principle calculations, is the most stable one among the clusters we considered and its electronic structure can explain the experimental observations. In this cluster, there is a strong pd bonding between Ti and C atoms, and the density of states at the Fermi energy is high.     

GEOMETRIC AND ELECTRONIC STRUCTURES OF Ti8C12 CLUSTER

The electronic structure of Ti₈C₁₂ clusters with three possible geometric structures suggested in the literature is studied using the discrete-variational local-density-functional method. The results show that the ground states of the clusters are all degenerate, which means further Jahn-Teller distortions for the geometric structures of clusters. The results also indicate that the distorted dodecahedral Ti₈C₁₂ cluster, which is proposed by Guo et al. and optimized by the first principle calculations, is the most stable one among the clusters we considered and its electronic structure can explain the experimental observations. In this cluster, there is a strong pd bonding between Ti and C atoms, and the density of states at the Fermi energy is high.     

北京谱仪端盖簇射计数器的建造与检测

描述了北京谱仪端盖簇射计数器的结构及制造工艺.并给出丝张力,暗电流、计数管工作特性等检测结果.     

线性组合预测在税收管理中的应用

本论述了组合预测理论中，对组合预测值采用“各个个体预测值的加权算术平均值”的不合理性，提出了用多重线性组合预测模型进行预测的方法，并将它运用于对××市税收的实际预测中去，预测精度高，效果好。     

掺Cr半绝缘GaAs中Si离子注入的载流子分布尾研究

本文研究了掺Cr半绝缘GaAs中²⁸Si⁺注入后的载流子浓度分布尾,包括退火温度和时间的影响。应用计算机模拟了分布尾对GaAsMESFET器件输出特性的影响,与实测结果符合,表明分布尾会造成器件输出特性异常。讨论了产生分布尾的原因,认为与GaAs衬底中残留Si等浅施主杂质和高温退火时Cr再分布有关。 关键词：     

Controlled Bidirectional Quantum Direct Communication by Using a GHZ State

A controlled bidirectional quantum secret direct communication scheme is proposed by using a Greenberger- Horne-Zeilinger （GHZ） state. In the scheme, two users can exchange their secret messages simultaneously with a set of devices under the control of a third party. The security of the scheme is analysed and confirmed.     

高稳定电化学扫描隧道显微镜研制

展示了一台自制的电化学扫描隧道显微镜. 这台电化学STM具有很高的稳定性,它在XY平面和Z方向的漂移速率分别为每分钟67和55.6 pm/min. 另外,特殊设计的扫描管部件有效地避免了在高湿度的环境中大漏电电流的产生. 详细描述了这台电化学STM的机械结构.通过在硫酸铜溶液中测量STM图像证明这套系统的优异性能,得到了大范围干净有序的Au(111)表面和高分辨的高聚石墨原子图像.