CdZnTe核探测器的蒙特卡罗模拟的初步研究

以CdZnTe核探测器的工作原理为依据,探测器内反应的随机性和反应产生的电子空穴对数目的统计规律为物理模型,应用Visual C + + 自行编制了蒙特卡罗模拟软件.模拟了γ射线在CdZnTe探测器中的响应能谱,并将模拟结果与实际器件的测试结果进行了比较讨论.模拟能谱与实际测得的能谱的主峰符合较好.此外,通过分析⁵⁷Co源辐照下探测效率与器件厚度的关系,可以推测探测效率达到最大时所对应CdZnTe探测器的理想厚度     

向量变分不等式的严格可行性问题

本篇文章首先定义了向量变分不等式的严格可行点概念,其次在假设了映射是强(D)-伪单调的情况下,证明了向量变分不等式解集非空有界与其严格可行点存在的等价性问题,推广了在数量变分不等式上得到的相应结果．     

TRANSFER OF FOREIGN GENES BY ELECTROPORATION AND THEIR EXPRESSION IN MAMMALIAN CELLS

Expression of foreign genes transferred into mammalian cells by electroporation has been studied. The pX1TK gene, pSV2Neo gene and pUCEJ oncogene have been introduced into MLTK-cells and NIH/3T3 cells, respectively. Stable transformation transient expression of TK gene by MLTK-cells as well as stable and malignant transformation of NIH/3T3 cells have been obtained. Transient expression frequency is about 80% and stable transformation frequency is about 10~(-4). Integration of foreign genes into the cellular genome was verified with molecular hybridization. Tumor development was observed after inoculation of transformed celts into nude mice.     

Phase transition in single crystal Cs2Nb4O11

We studied temperature dependence of complex capacitance, impedance, and polarized Raman spectra of single crystal Cs2Nb4O11. First, we observed a sharp lambda-shaped peak at 165 degrees C in the complex capacitance, then found drastic changes in the Raman spectra in the same temperature range. Utilizing the pseudosymmetry search of structure space group, we attributed the observed anomalies to a structural change from the room temperature orthorhombic Pnn2 to another orthorhombic Imm2. We also measured room temperature polarized Raman spectra in different symmetries of normal vibrations and assigned high wavenumber Raman bands to the internal vibrations of NbO6 octahedra and NbO4 tetrahedra.     

铁轴草中Teucvidin的衍生物研究

从唇形科植物铁轴草中分离得去甲克罗烷二萜化合物Ｔｅｕｃｖｉｄｉｎ，通过催化氢化、酯交换、水解等反应合成了８个衍生物，用＾１ＨＮＭＲ、ＭＳ和ＩＲ确定了其结构，初步生物活性测定结果表明，化合物Ⅱ和Ⅳａ的拒食作用显著。     

ISOLATION,CHARACTERIZATION AND EXPRESSION OF THE COMPLEMENTARY DNA FOR HUMAN TUMOR NECROSIS FACTOR (TNF-α)

A cDNA for human TNF-α (615bp) was isolated by means of polymerase chain reaction (PCR) using first strand cDNA from PMA-induced HL-60 cells as template. The result from sequencing the 615 bp cDNA fragment indicated that it corresponded to the entire sequence of mature human TNF coding region. Direct expression of mature human TNF was achieved using a plasmid pHT-1 constructed by ligation of the cDNA and a synthetic DNA. The IPTG-induced bacterial product (hTNF) showed cytotoxicity to mouse L-929 cells. The TNF activity was further identified by neutralization of a specific monoclonal antibody against human TNF-α. Approximately 80,000 units of activity were detected per ml of culture at A600=2.     

改进Hückel模型变分法与同系线性规律

一、引言同系线性规律可以表示为:P=a+bF(N)其中P是同系化合物的物理化学性质,a、b 是常数,F(N)是同系线性函数,N=n+t,n 是同系序数,t 是端基当量。人们在探求 F(N)方面做了较多的工作,最近的有以下几个:     

HRP-12催化剂上苯与直链烯烃的烷基化反应 Ⅰ. 本征反应动力学研究

直链烷基苯是生产阴离子表面活性剂直链烷基苯磺酸盐的重要原料。2000年以美国环球油品公司(UOP)的脱氢法工艺生产的直链烷基苯占世界直链烷基苯产量的88％。脱氢法以液体氢氟酸为催化剂由正构烯烃与苯进行烷基化反应生产直链烷基苯。由于液体氢氟酸催化剂具有较强的腐蚀     

在线社交网络控制实验的现状与展望

在线社交网络已发展成为一个独特的电子生态系统,其应用深刻影响着人们生活的方方面面。由于在线社交网络特性复杂,分析在线社交网络形成和变化中的规律成为当前计算机科学、社会学和物理学的一项挑战。传统上,在线社交网络实证研究主要采用计算机辅助的被动数据获取和分析方式。近年来,在真实大规模在线社交网络上直接进行控制实验从而主动获取数据并开展分析研究的方式广受关注。评述了这一领域的研究进展,包括：社交网络控制实验的主要研究模式;控制实验方法在社交网络结构、信息传播、行为和心理学等领域取得的主要成果以及主要实验工具的适用条件和局限性。最后,展望了人工智能技术在社交网络控制实验中的应用潜力,分析了智能算法对降低实验成本和提高实验效率的作用。     

溴鼠灵与DNA作用机制的光谱研究

农用化学物质残留可能会与DNA结合形成加和物,从而对动物和人类造成危害。文章利用紫外光谱和荧光光谱研究了溴鼠灵(BDF)与小牛胸腺DNA(ct-DNA)的作用机理。结果表明,低浓度的ct-DNA可使BDF的吸收光谱发生减色,ct-DNA对BDF的稳态荧光有明显的的猝灭作用,属于静态猝灭方式,27 ℃时K_SV=1.21×104 L·mol-1;根据热力学参数推测BDF与ct-DNA之间的相互作用主要是范德瓦耳斯力作用;猝灭试验发现ct-DNA对BDF无明显保护作用;离子强度改变时,BDF/ct-DNA体系的荧光强度也随之改变;ct-DNA对β-CD/BDF包络物的荧光也有猝灭,但猝灭程度比游离的BDF有所降低,表明β-CD对BDF具有保护作用,也说明BDF与ct-DNA或β-CD的结合具有竞争性。各试验结果一致表明BDF与ct-DNA之间主要是以沟区结合方式发生作用。另外,试验结果也表明BDF与ct-DNA之间还存在静电作用。范德瓦耳斯力和静电作用的共同作用,为BDF在沟区与DNA的相互结合提供了更好条件。