“VEM”X射线结构分析仪的改装

“VEM”X射线结构分析仪是五十年代初从东德进口的产品,这批仪器被许多高等院校和科研单位在使用着。然而在十年动乱期间很多单位对该仪器未能进行妥善保管,随机进口的FA型X射线管都已损坏,而且该型号管子已属过时产品,不再生产。目前生产的X射线管如荷兰的“菲利浦”和国产JX_4—50在外形和几何尺寸上都与它有很大差异,无法在“VEM”机上安装使用。为了节省国家开支,使这批仪器重新发挥作用,我们改装了一台“VEM”     

激光视网膜凝结机

激光是六十年代兴起的一门新技术.我们成立了研究、生产、使用三结合协作组,制成了激光视网膜凝结机,使这门新技术在眼科治疗中得到了成功的应用. 激光视网膜凝结机可封闭视网膜裂孔,以达到防治视网膜脱离的效果. 视网膜是形成视觉的主要部分.外界景物经过眼睛的角膜、房水、晶状体、玻璃体后,在视网膜上成像.通过视神经传导到大脑,便形成视觉.视网膜具有多层结构,其中在神经上皮层(布满着视细胞)与色素上皮层(含有丰富的黑色素)之间存在着潜在性空隙.在正常情况下,这两层组织靠着玻璃体向外支撑的压力和脉络膜毛细血管的吸引力而保持紧密接…     

Composites of nanotubular polyaniline containing Fe3O4 nanoparticles

Results of charge-transport and magnetic measurements of nanotubular polyaniline (PANI) composites containing Fe_3O_4 nanoparticles (～10nm) synthesized by a "template-free" method are reported. The T^{-1/2} resistivity has been observed, and dc magnetic susceptibility data are fitted to an equation χ=χ^*_P+C/T. With increasing weight ratio of Fe_3O_4, the electrical conductivity and temperature- independent susceptibility χ^*_P increase, and the Curie-type susceptibility is suppressed at low temperatures. Further discussions have been given. The PANI-H_3PO_4/Fe_3O_4 composite containing 27wt% of Fe_3O_4 nanoparticles is superparamagnetic, exhibiting very little hysteresis even at 5K.     

Small Stress Change Triggering a Big Earthquake： a Test of the Critical Point Hypothesis for Earthquakes

Whether or not a small stress change can trigger a big earthquake is one of the most important problems related to the critical point hypothesis for earthquakes. We investigate global earthquakes with different focM mechanisms which have different levels of ambient shear stress. This ambient stress level is the stress level required by the earthquakes for their occurrence. Earthquake pairs are studied to see whether the occurrence of the preceding event encourages the occurrence of the succeeding one in terms of the Coulomb stress triggering. It is observed that the stress triggering effect produced by the change of Coulomb failure stress in the same order of magnitudes,about 10-2 MPa, is distinctly different for different focal mechanisms, and thus for different ambient stress levels.For non-strike-slip earthquakes with a relatively low ambient stress level, the triggering effect is more evident,while for strike-slip earthquakes with a relatively high ambient stress level, there is no evident triggering effect.This water level test provides an observational support to the critical point hypothesis for earthquakes.     

我国某地区居民购买六合彩活动信息的统计分析

本文主要应用统计学方法对由问卷调查所获得的我国某地区居民购买地下六合彩活动的信息进行分析,分别对购买者的结构,经济状况及收益进行分析,指出地下六合彩的本质及这一现象给我们的警示.同时通过分析一个消费者个体的消费模型给出消费者如何理性消费的建议.     

计算机辅助彩色立体图像生成中的误差分析与处理

柱透镜光栅的计算机辅助立体成像的基本原理是将二维序列图像进行切分和重组,使之以三维模型的形式展现,使合成的图像在柱透镜光栅下观察时具有"纵深感"。该项技术在广告、摄影、电影制作中具有广泛的应用。但是长期以来,在图像切分时并不能保证像素一定被整除,这意味着剩余像素的出现,合成的立体图像必然存在误差。如何处理剩余像素的问题一直是个难题,阻碍了该技术的推广。针对立体图像生成方法中的剩余像素问题,详尽地分析了误差的形成,并提出了强行取整算法和误差分散算法两种误差处理方法。实验表明,这两种算法能较好的处理剩余像素,增强了合成图像的立体效果,这将有助于立体成像技术的进一步推广。     

外加电场对光折变高阶响应影响的微扰分析

应用微扰展开法了“跳跃模型”给出了空间电荷场前三阶分量随时间，外加电场等变化的解析表达式，同时讨论了外加电场对各阶空间电荷场建立的影响，当扩散与外加电场可比拟时，外加电场对空间电荷场的影响不大，随着空间电荷场阶数的提高，其达到最大饱和值所需的外加电磁越小，在外加电场作用下，空间电荷场各阶分量随时间呈振荡衰减，直到达到饱和，外加是场越大，振荡越强烈，周期越短，在考虑高阶分量的贡献后，空间电荷场的振荡     

Analysis of secondary electron emission using the fractal method

Based on the rough surface topography with fractal parameters and the Monte–Carlo simulation method for secondary electron emission properties, we analyze the secondary electron yield(SEY) of a metal with rough surface topography. The results show that when the characteristic length scale of the surface, G, is larger than 1 × 10^-7, the surface roughness increases with the increasing fractal dimension D. When the surface roughness becomes larger, it is difficult for entered electrons to escape surface. As a result, more electrons are collected and then SEY decreases. When G is less than 1 × 10^-7,the effect of the surface topography can be ignored, and the SEY almost has no change as the dimension D increases. Then,the multipactor thresholds of a C-band rectangular impedance transfer and an ultrahigh-frequency-band coaxial impedance transfer are predicted by the relationship between the SEY and the fractal parameters. It is verified that for practical microwave devices, the larger the parameter G is, the higher the multipactor threshold is. Also, the larger the value of D,the higher the multipactor threshold.     

烷基极化效应与羰基13C化学位移

对羰基化合物中羰基碳的¹³C NMR化学位移与烷基（R）极化效应的内在关系 进行了研究. 结果表明：分子中R的极化效应增加使羰基碳的¹³C化学位移值升 高,其关系可表示为δ=a+b·ΣPEI(R),其中a、b为系数,PEI（R）为R极化效应指数.
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EXISTENCE AND UNIQUENESS THEOREMS FOR HIGHER-ORDER BOUNDARY VALUE PROBLEMS

An existence and uniqueness of solutions for boundary value problemsandare established, by employing a priori estimates for all solutions and the Schau-der fixed point theorem. Some of these results extend earlier results due toUsmani(1979), Yang(1988), and Pei(1997).