碱存在下二烷基硼酸甲酯与氯仿的相转移反应研究

由烯烃经一氯硼烷甲硫醚（Ｈ２ＢＣｌ·ＳＭｅ２）硼氢化和甲醇解制得的二烷基硼酸甲酯６，在５０％ＮａＯＨ和相转移催化剂（ＴＥＢＡ）存在下与氯仿反应，继之氧化，获得了相应的二烷基酮１，二环烷基酮２和３以及脂环酮４．考查了各种参数对反应的影响．讨论了反应机理，为从烯烃出发合成各种类型的酮提供了一条简便新途径．     

Small amplitude ion-acoustic double layers with cold electron beam and q-nonextensive electrons

Small amplitude ion-acoustic double layers in an unmagnetized and collisionless plasma consisting of cold positive ions, q-nonextensive electrons, and a cold electron beam are investigated. Small amplitude double layer solution is obtained by expanding the Sagdeev potential truncated method. The effects of entropic index q, speed and density of cold electron beam on double layer structures are discussed.     

大学物理教学中如何培养等效思维

等效思维是物理学授课过程中的一种思维方式,也是工程技术中的一种重要方法.它是将复杂的物理现象及过程转化为简易的物理现象和过程来研究和处理的一种科学思维方法.常用的有研究对象、物理量、物理过程、物理状态、物理模型、物理作用等的等效.     

Electron-mediated ferromagnetism in Fe-doped InP: Theory and experiment

We report on the electron-mediated ferromagnetism in Fe-doped InP from both first-principles calculations and experiments. Theoretically, based on the spin-polarized density functional theory within the Heyd-Scuseria-Ernzerhof (HSE03) approach, we systematically investigate the magnetic properties of Fe-doped InP and predict the existence of electron-mediated ferromagnetism. Experimentally, by diffusing Fe into the n-type InP wafer with thermal annealing at 800 C, we observe room-temperature ferromagnetism in InP:Fe, which is in agreement with the theoretical prediction.     

多核环境下潮汐分析辅助软件并行绘制技术研究

为方便科研人员使用Baytap-G潮汐分析软件,基于C#.NET程序设计语言设计了一套潮汐分析辅助软件,实现了Baytap-G软件的封装,完成了输入数据格式的自动转换、输出数据的自动提取,以及水位、振幅、相位数据的可视化展示;在介绍C#.NET语言中任务(TASK)并行编程模型的基础上,详细讨论了绘制振幅、相位图任务分解、并行化程序设计考虑及其实现;实验结果表明,合理设计并行程序可以充分利用多核计算机的计算资源,提升程序运行效率,但是过多的任务数、不均匀的工作负载通常会影响并行程序的效率。     

Fractional Fourier-domain random encoding and pixel scrambling technique for double image encryption

A double image encryption method is proposed using fractional Fourier-domain random encoding and pixel scrambling technique. One of the two original images is encoded into the phase function of a synthesized input signal after being scrambled, and the other original image encoded into its amplitude. The phase function serves as phase mask in the input domain, and the synthesized input signal is then encrypted into stationary white noise by utilizing random phase encoding in fractional Fourier domain. The two original images can be retrieved without cross-talk by using the correct keys with fractional orders, the random phase mask and the pixel scrambling operator. Numerical simulations and security analysis have been done to prove the validity and the security of the proposed encryption method.     

Primary result of ~(236)U measurement with accelerator mass spectrometry at CIAE

The rare isotope 236U has a half-life of 2.342(3)×107 years,and is produced principally by thermal neutron capture on 235U.The isotopic atom ratio of 236U/238U depends on the integral thermal neutron flux received by the material of interest.236U is potentially useful as a fingerprint for indicating the presence of neutron-irradiated uranium usually originating from nuclear activity.By extracting negative molecular ion UO- from the uranium oxide target,simulating the 236U16O- beam transport with 238U16O- an...     

广义H non映射的滑模变结构控制同步

基于可线性化的非线性离散变结构跟踪控制方法实现了广义H non映射混沌系统的同步 .广义H non映射的混沌吸引子比H non映射的混沌吸引子要复杂得多 ,对于保密通信来说 ,这种复杂性正是所期望的 .提出的同步方法允许参数有适当的失配程度 ,这对工程实现是非常有利的 ,理论分析和仿真结果证实了该方法的有效性     

Mechanical stability and thermodynamic properties of OsC from first-principles calculations

The elastic and thermodynamic characteristics of OsC crystal have been predicted through a method of density functional theory within the generalized gradient approximation (GGA). Compared with WC-type OsC, NaCl-type OsC is not only energy unfavorable but also mechanics unstable. The five independent elastic constants (C_ij), bulk modulus (B₀), the dependence of bulk modulus on temperature and pressure as well as the thermal expansion coefficient (α_V) at various temperatures for WC-type OsC are discussed. According to our calculations, WC-type OsC should be an ultra-incompressible material with high bulk modulus about 381 GPa. In addition, the bulk modulus will increase with increasing pressure while decrease with increasing temperature. The researches on the thermal expansion coefficient indicate that there will be a knee point during the process of thermal expansion coefficient variation versus increasing temperature. Our results may provide useful information for theoretical and experimental investigation of OsC.