大戟属三萜类结构及生物活性*

大戟属植物在全世界分布有2000多种,对于本属植物二萜类成分及生物活性的综述报道较多,但是还未见关于三萜类化学成分及生物活性的综述报道。本文综述了该属植物各种类型三萜化合物（羊毛脂烷型、环阿尔廷烷型、大戟烷型、甘遂烷型、齐敦果烷型、乌苏烷型及羽扇豆烷型等）的化学性能以及抗肿瘤、抗炎抗菌、抗病毒等主要生物活性的研究。     

Propagation properties of electromagnetic fields in elliptic dielectric hollow fibres and their applications

We numerically calculate and analyse the electromagnetic fields, optical intensity distributions, polarization states and orbital angular momentum of some elliptic hollow modes in an elliptic dielectric hollow fiber (EDHF) by using Mathieu functions, and also calculate the optical potential of the blue-detuned _eHE₁₁ mode evanescent-light wave for ⁸⁵Rb atoms, including the position-dependent van der Waals potential, and discuss briefly some potential applications of our EDHF in atom and molecule optics, etc. Our study shows that the vector electric field distributions of the odd modes in the cross section of the EDHF are the same as that of the even modes and with different boundary ellipses by rotating an angle of π/2, and the orbital angular momentum (OAM) of single HE (EH) mode is exactly equal to zero, while that of dual-mode in the EDHF is fractional in h, and has a sinusoidal oscillation as z varies. The EDHF can be used to produce various elliptic hollow beams, even to generate and study various atomic vortices with a fractional charge and its fractional quantum Hall effect in atomic Bose--Einstein condensate, and so on.     

光通信系统中色散容限的分析

文章通过非线性薛定谔方程和主偏振态(PSP)模型.对单模光纤中色散引起的脉冲展宽进行了研究.通过详细计算,对光通信系统中的色度色散和偏振模色散(PMD)做出了合理的估计,并分析了色散容限对系统传输的影响.这些分析对实际系统设计具有一定参考意义.     

优于12dB压缩态光场的产生与观察

压缩态、振幅压缩态和非经典相关态光场等均为非经典光场。压缩态体现着光场的一种新的量子特性,对它的研究有着重大的科学意义;而且因其电场正交相分量之一的量子噪声可低于散粒噪声极限(shot noise limit简称SNL)在光通信、光计算机、光学精密测量及光谱学、非线性光学中有着十分诱人的应用前景。 继非经典相关态光场产生与观察后,最近作者采用负反馈半导体激光器和平衡零拍探测器成功地产生并观察到了低于散粒噪声极限以下12dB的压缩态光场。本文所报道的产生压缩态光场的实验方案不同于业已报道的参量产生方案(如参量转换、四波混频等):首先实验利用半导体激光器作光源,经分束器将很少一部分光作为信号光束,而其主要部分光作为本振光束。没有用到光学腔,强泵浦光和非线性材料;其次,采用了信号光场量子涨落的     

磁防垢除垢技术及机理探讨

本文简述磁防垢、除垢技术，探讨了磁防垢、除垢机理。     

美国大联盟HDTV数字伴音编码标准

目前世界上正在进行数字式高清晰度电视技术的研究。文章简要介绍了美国大联盟数字式ＨＤＴＶ性能优良的数字伴音编码Ｄｏｂｌｙ的ＡＣ－３编码技术的主要原理及特点。     

A Novel Electrostatic Guiding Scheme for Cold Polar Molecules in Weak-Field-Seeking States

We propose a novel electrostatic guiding scheme for cold polar molecules in weak-field-seeking states using a single charged wire half embanked in a ceramic substrate (i.e., a chip) and a homogeneous bias electric field, which is produced by a capacitor composed of two large parallel metal plates. We calculate the spatial distribution of the electrostatic fields generated by the combination of the charged wire and the plate capacitor and the corresponding trapping potentials for CO molecules, and analyse the relationships between the electric field and the parameters of the charged-wire layout. Our study shows that the proposed scheme with a single charged-wire can be used to guide cold polar molecules in the weak-field-seeking states, and has some potential applications in construction of various molecule-optical elements.     

一种新颖的表面光波导型原子(或分子)分束器

提出了一种采用二元π位相板与柱面透镜组合而构成表面光波导型原子（或分子）分束器及其Mach-Zehnder干涉仪与X-分束器列阵的新方案，介绍了本方案的物理思想与基本原理，导出了光强分布、强度梯度、分束距离和分束路径的宽度与光学系统参数间的解析关系，并分析和讨论了本方案的潜在应用及其可行性. 研究表明，本方案设计新颖、光路简单，便于与其他元件组合构成具有表面微结构的集成原子（或分子）光学元器件及其全光型原子（或分子）芯片. 关键词： 原子（或分子）光波导 原子（或分子）分束器 原子（或分子）芯片 二元π位相板