微光像增强器图像传递信噪比的测试研究

图像传递信噪比是微光像增强器的重要特性参数．能够全面定量地表征像增强器在探测弱辐射图像时的综合性能，对于确定像增强器的图像探测灵敏闽具有重要意义。针对其测试原理．采用高灵敏度低噪声CCD器件作为像管输出图像的探测接收器．并引入数字图像处理技术。利用设计的测试系统实现了典型目标图像传递信噪比的自动测试．多次实验结果表明．陔测试系统具有测试过程自动快速及测试数据准确稳定的优点．相同测试条件下的不确定度优于±3%。     

谈普朗克质量

简要介绍了普朗克于1912年提出的三个基本物理量：普朗克质量、普朗克长度和普朗克时间，它们巳被列入1986和1998年基本物理常数表，该文只讨论普朗克质量，假定原子核内存在量子化的核力场，命名其场量子为“引斥子”，其质量推算出恰好等于普朗克质量，由此可用4个耦合常数定量地描述四种相互作用的强度比，从而还可找到一种测定G的新方法。     

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.     

Shear and extensional rheology of entangled polymer melts: Similarities and differences

This work extends our previous understanding concerning the nonlinear responses of entangled polymer solutions and melts to large external deformation in both simple shear and uniaxial extension. Many similarities have recently been identified for both step strain and startup continuous deformation, including elastic yielding, i.e., chain disentanglement after cessation of shear or extension, and emergence of a yield point during startup deformation that involves a deformation rate in excess of the dominant molecular relaxation rate. At a sufficiently high constant Hencky rate, uniaxial extension of an entangled melt is known to produce window-glass-like rupture. The present study provides evidence against the speculation that chain entanglements tie up into "dead knots" in constant-rate extension because of the exponentially growing chain stretching with time. In particular, it is shown that even Instron-style tensile stretching, i.e., extending a specimen by applying a constant velocity on both ends, results in rupture. Yet, in the same rate range, the same entangled melt only yields in simple shear, and the resulting shear banding is clearly not a characteristic of rupture. Thus, we conclude that chain entanglements respond to simple shear in the manner of yielding whereas uniaxial extension is rather effective in causing some entanglements to lock up, making it impossible for the entanglement network to yield at high rates.     

Elastic breakup in uniaxial extension of entangled polymer melts

Five entangled melts, with the number of entanglements per chain ranging from 25 to 160, have been studied to illustrate how cohesive strength can be overcome in either continuous or interrupted extension (i.e., during or after uniaxial stretching). The internal elastic stress due to chain deformation from imposed strain appears to be the cause of the observed yielding behavior that reveals scaling laws. The visual signature of the elastic breakup is the occurrence of nonuniform extension. The yield phenomena may be understood at a force level.     

Er3+掺杂Li2O-SrO-ZnO-Bi2O3玻璃中Er3+离子在1.53 μm处的荧光发射特性

采用传统的熔融法制备了Er~(3+)掺杂的新型铋酸盐玻璃(Li_2O-SrO-ZnO-Bi_2O_3,LSZB),并对其光谱性质进行了表征,分析了玻璃的拉曼光谱、吸收光谱、荧光光谱,利用Judd-Ofelt理论研究了其荧光特性。LSZB玻璃样品中Er~(3+)的~4I_(13/2)→~4I_(15/2)跃迁发射峰位于1.53 μm处,半高宽约为78 nm。样品中Er~(3+)的~4I_(13/2)能级寿命为2.848 ms,量子效率为99.93%,受激发射截面达到9.76×10~(-21)cm~2。以上结果显示,Er~(3+)掺杂LSZB玻璃有良好的光谱特性。     

容器壁厚度对光栅衍射法测量液体折射率的影响

利用光栅衍射法测量了NaCl溶液的折射率,并分析了容器壁厚度引起的附加光程对折射率的影响.采用折射率修正公式运用一级衍射得到的溶液的折射率更可靠.     

草酸钙结石形态的红外光谱分析

草酸钙结石主要是以一水草酸钙(COM)、二水草酸钙(COD)的形式存在。在解决缺少COD标样的难题后,将制备的COD样品与COM标样混合,然后采用红外光谱法对混合物进行分析研究,采用谱带比值法,确定了COD和COM在660和610 cm-1处与780和520 cm-1处的吸收度比值(R)与质量分数(w)的关系式,其线性回归方程分别为:R=11.95×10-3wCOD 0.873 61,r=0.983 63;R=4.74×10-3wCOD 0.886 52,r=0.992 44。同时为了减少压片、测定等因素引起的误差,采用零点交叉一阶导数法,测定在1 320 cm-1处吸收度一阶导数与COD质量分数(w)的关系式,其线性回归方程I=5.5×10-5w 9.2×10-5,r=0.996 60。线性良好。     

二氧化碳对同质外延生长单晶金刚石内应力的影响

本文研究了在反应气体中引入不同浓度的CO₂对微波等离子体化学气相沉积(MPCVD)法同质外延生长单晶金刚石内应力的影响,并对其作用机理进行了分析。研究发现,随着CO₂浓度增加,单晶金刚石内应力逐渐减小,这是由于添加的CO₂提供了含氧基团,可以有效刻蚀金刚石生长过程中的非金刚石碳,并能够降低金刚石中杂质的含量,从而避免晶格畸变,减少生长缺陷,并最终表现为单晶金刚石内应力的减小,其中金刚石内应力以压应力的形式呈现。此外反应气体中加入CO₂可以降低单晶金刚石的生长速率和沉积温度,且在合适的碳氢氧原子比(5∶112∶4)下能够得到杂质少、结晶度高的单晶金刚石。     

石墨炉原子吸收法测定石脑油中微量砷

试样用四氢呋喃（THF）有机溶剂稀释,以硝酸镍为基体改进剂,研究采用石墨炉原子吸收法直接进样测定石脑油中的砷量。研究表明,砷量在0～50μg／L范围内线性关系良好,回收率93％～104％。