二硅化钼机械球磨过程的研究

通过X射线衍射仪、电子显微镜和ZJM10T型搅拌机研究了MoSi2粉末球磨过程.结果表明:机械球磨过程中,MoSi2粉末的衍射峰强度随球磨时间的增加不断减弱且逐渐宽化;其机械化学变化随球磨时间的延长表现为:晶粒尺寸减小,显微应变增加,有效温度系数增加.机械化学效应因子之间的变化关系如下:晶粒尺寸与有效温度系数和显微应变呈逆变关系;显微应变随有效温度系数增加而增大.     

火车车钩舌面仿形自动堆焊机仿形系统设计

火车车钩舌面经常需要进行焊补，传统的手工堆焊工效低且质量差，为配合仿形自动堆焊机的研制，本文设计了自动堆焊机的控制系统，该系统采用眦控制技术，两个伺服电机、一个步进电机驱动和三维精密工作台机械传动，实现三坐标、多道自动堆焊，保证S面精确成型。经过调试及模拟运行后表明，该控制系统能使焊枪运动轨迹为要求的S形，并使Z向工作台在规定的时间内上下运动，保证了自动堆焊机的仿形精度和工作效率，达到其技术要求。     

纤维网片复合方式对纤维增强水泥基材料性能的影响

在分析渍浆纤维混凝土(SIFCON)和渍浆网片混凝土(SIMCON)各自优缺点的基础上，研究了不同性质乱向短纤维和定向纤维网片复合及不同性质网片组合方式对纤维增强混凝土性能的影响．实验结果表明：各种纤维体积分数下定向网片与乱向短纤维复合增强混凝土各项性能明显优于单用乱向短钢纤维增强混凝土；当纤维总体积分数为8％时，由2层细孔编织钢丝网和3层细孔玻纤网组合网片型式B(网片体积分数为0．7％)与乱向短纤维(体积分数为7．3％)复合增强混凝土，其抗弯强度、抗剪强度、弯曲韧性(I5)比短切钢纤维增强混凝土(SIFCON)分别提高了45％，25％和46％，从而揭示了高弹模与低弹模纤维复合、乱向纤维与定向纤维网复合，优化纤维分布和取向，使其在材料层次和结构层次协同作用的优势得以发挥，并以较低的成本和较方便的施工工艺制备了高性能纤维增强水泥基复合材料。     

Efficient expression of human factor Ⅸ cDNA in liver mediated by hydrodynamics-based plasmid administration

The transfection of plasmid DNA into mammalian cells is an indispensable tool in the study of gene transfer and gene function. Since the original report in 1990 on the successful expression of a reporter gene in muscle[1], plasmid DNA injection has been widely used to mediate gene transfer study. As a gene transfer vector, naked DNA has many obvious advantages. It is easy and cheap to be prepared and more safe after transfection. But the plasmid mediated gene expression is low because of t…     

Shift visual cryptography scheme of two secret images

A new visual cryptography scheme of two secret images, which is named the shift visual cryptography of two secret images, is given. The compound function family of a general construction model is also introduced. The uniqueness and validity of this model are proved, and the minimum rows and columns for realizing the scheme are obtained. Compared with visual cryptography of one secret image, the shift visual cryptography scheme can share two secret images with the same size of pixels expansion without losing the contrast. It has randomness and various forms, and furthermore, we can also visually recover two secret images even if the two shares are different in form and color.     

Rapid cold hardening process of insects and its ecologically adaptive significance

In contrast to overwintering cold hardening, a rapid cold hardening process has recently been described in insects. This process can rapidly enhance cold tolerance of insects in several hours or even minutes. The characteristics of rapid cold hardening include inducing conditions, cold hardening effects, and fitness costs. Physiological and biochemical mechanisms of rapid cold hardening include rapid changes in the phospholipid composition and the increase in hemolymph osmolalities, polyols production, proline and cold-induced proteins. Moreover, there are different views about the ecologically adaptive significance of rapid cold hardening in insects. This paper reviews research results about rapid cold hardening of insects since 1987, focusing on forms of cold injury, strategies of cold tolerance, and definitions, characteristics, physiological and biochemical mechanisms and adaptive significance of rapid cold hardening.     

井下掺液抽稠油泵研究

通过对常规泵进行串联、改造 ,研制出了井下掺液抽稠油泵。对泵结构的可行性进行了论证 ,阐述了泵的工作原理 ,并对泵的工作参数进行了分析。该泵是通过从油管掺入液、从油套环空产出液 ,在上冲程时吸入产出液 ,在下冲程时举升混合液 ,从而实现了在柱塞下方掺液 ,避免了出现砂磨柱塞的现象 ,减少了稠油对柱塞运动的阻力 ,克服了泵上掺液不能降低进泵原油粘度的缺点 ,解决了在井筒降粘和稠油抽汲中存在的问题。该泵使用了连动式凡尔与弹簧 ,保证了底阀与顶阀打开与关闭的同步性 ,能够达到吸入产出液、加入掺入液以及举升混合液同时进行的目的。该泵的设计原理可行 ,工艺容易实现 ,是一种理想的新型抽稠油泵。     

Building of hFⅨ transgenic mice by spermatogenic cells

Human FⅨ expression vector pCMVⅨ was packaged by effectene^TM reagent and injected into mice seminiferous tubules with glass pipettes.The expressional frame of pCMVⅨ was examined by PCR and Southern blotting among 41 progenies.There were 2(4%) mice being integrated with hFⅨ gene into chromosomes.4.6ng/mL of hFⅨ protein was expressed in plasma of one mouse,which was tested by ELISA.We demonstrated that building of transgenic animals by spermatogonial stem cells is an efficient method.Meanwhile,it has also been proved to be an alternative choice for mammary gland bioreactor.     

干燥控制化学添加剂在制备硅气凝胶中的应用

以硅溶胶为主要原料,通过硅溶胶体系的凝胶过程中添加干燥控制化学添加剂(DCCA),并结合非超临界干燥技术制备了硅气凝胶,研究了DCCA对凝胶过程和最终所得气凝胶品质的影响。DCCA能使凝胶的生成时间增加,凝胶结构均匀化,构成凝胶的基本微粒的粒径有所减小。在一定的DCCA添加量范围内,随着DCCA添加量的增加,所得气凝胶样品的密度有所减小,比表面积增加,微观结构变得更加完善,孔分布也更加集中。不同DCCA对气凝胶品质的影响规律不尽相同,气凝胶的品质就有可能通过调节添加DCCA的种类和量得到控制。     

演绎数据库虚关系的内部表示

介绍了演绎数据库的系统结构，并着重介绍了基于SQL Serverr之上的递归查询算法和将以规则形式存放于外存的虚关系转化为内部表示的过程。