Synthesis and mesomorphic properties of trifluorobenzoate liquid crystal

Four series of trifluorobenzoate liquid crystals have been synthesized. Their phase transition temperatures have been also measured by texture observation in a polarizing microscope and confirmed by DSC. The influence of the lateral fluoro-substitution and triple bond has been also discussed.     

基于ERP的(s,S)策略下库存优化控制决策支持系统

针对当前ERP软件系统无法动态地给出优化订购策略并对历史数据进行有效的分析等不足,以最小化库存费用为目标建立起折扣准则下库存优化数学模型,对ERP软件中导出的各类历史数据进行模型化分析,动态地得出各类产品(s,S)结构形式的优化订购策略.基于该模型设计并开发了库存优化控制决策支持系统,为用户提供决策支持,很大程度降低了企业库存费用.     

Supramolecular assembly of three d~(10) metal coordination polymers based on the naphthalene-1,8-dicarboxylate ligand:Syntheses,structures and luminescent properties

Three d10 tetranuclear complexes,Cd 4(1,8-nap) 4(2,2′-bipy) 4(H2O) 8·6H2O(1,8-nap=naphthalene-1,8-dicarboxylate and 2,2′bipy=2,2′-bipyridine)(1),Cd4(1,8-nap) 4(2,2′-bipy) 4(H2O) 8·6H2O(2) andZn4(1,8-nap) 4(2,2′-bipy) 4(H2O) 4·2H2O(3),have been synthesized under hydrothermal conditions and characterized by elemental analyses,IR and X-ray diffraction techniques. Complexes 1 and 2 are isomers showing one-dimensional ribbon-like structures connected by O-H···O hydrogen bonds,and the one-dimensional ribbons are ...     

新型立方体多核异金属配合物的合成及其晶体结构

在水热条件下,2-甲基咪唑4,5-二羧酸(H3MIDC)与醋酸钴反应,合成了新的[CO8(HMIDC)12]8-立方体结构单元的多核杂金属配合物(1),其结构经单晶x-射线衍射和元素分析表征.1属三方晶系,R-3空间群,晶胞参数a=24.407 9(17)(A),b=24.4079(17)(A),c=25.140(3)(A),α=90°,β= 90°,γ=120°,V=12971(2)A3,Z=45,Mr=272.12,Dc=1.568 Mg·m-3,μ=1.510 mm-1.F(000)=6210,GOF=1.347,Rint=0.0851,Ri=0.0848,wR2=0.2544.12个配体将8个Co离子连接成-个立方体结构,12个Na(I)离子连接相邻的立方体结构形成一个三维的超分子结构.     

ESTIMATION OF ACTIVATED ENERGY OF DESORPTION OF n-HEXANE ON ACTIVATED CARBONS BY TPD TECHNIQUE

1. INTRODUCTION In some cities of China, cancer and breath system diseases caused by the pollution of volatile organic compounds (VOCs) have been obviously increasing. The VOCs includes BTEX (benzene, toluene, ethylbenzene, and xylene), aldehydes, cresol, phenol, acetic acid, polynuclear aromatic hydrocarbons (PAHs), which have long-term human health implications. Emission of the VOCs has threatened the health of people seriously [1,2]. The pollution of the VOCs mostly hails from…     

90Mo电磁跃迁几率的测量

利用束流能量为116MeV的⁵⁹Co(³⁵Cl,2p2n)⁹⁰Mo反应布居⁹⁰Mo的高自旋态.用10台反康普顿HPGe探测器组成的探测阵列进行γγ符合测量.通过多普勒展宽峰的形状分析测定⁹⁰Mo高自旋态的寿命.在正宇称衰变系观察到增强的M1跃迁,推断I=13以上是扁椭形变.负宇称高自旋态具有大的B(E2)值,并随自旋增大而起伏变化.正、负宇称态之间的跃迁显示增大的E1跃迁,似有八极关联的可能.但是,⁹⁰Mo并不处在理论预言的存在八极形变的核区内.     

One-pot tandem Barbier-Prins synthesis of tetrahydropyrans in aqueous media

Tetrahydropyran is an important structural core ofmany carbohydrates and their polymers. Its structure ispresent in numerous natural compounds such as poly-ether antibiotics, marine toxins and pheromones[1,2].Thus many reactions have been developed toward…     

Compensation for Self-Focusing of Picosecond Pulses in Nd：Glass by Using Cascaded Quadratic Nonlinearity

One of the obstacles in obtaining high power/energy laser sources is self-focusing, which stems from the nonlinear phase shift (B-integral) accumulated during beam propagation in Kerr media. Phase-mismatched secondharmonic generation may impose a nonlinear phase shift on the fundamental with controllable sign and magnitude,which can be used to compensate for self-focusing with a single-pass configuration. We have demonstrated such a possibility for picosecond pulses theoretically and experimentally, and both configurations of pre- and postcompensation by a β-barium borate crystal have been studied in detail. Cascaded second-order nonlinearity-based compensation for self-focusing may provide an auxiliary means to the conventional B-integral control techniques.     

随机共振的模拟实验

用模拟电路的方法对随机共振现象进行多方面的实验研究,讨论随机共振机制,测量输出信噪比(SNR),由于在随机共振过程中部分噪声能量可转变为信号能量,利用这个机制可能在强噪声对信号的抑制下取出信号。 关键词：     

高精度全息干涉计量—相移技术的应用

本文介绍了一种精确的全息干涉相位测量系统。采用双曝光、双参考光束,并引入相移技术,能够同时获得全场256×256个点的相位变化值;相位测量的重复性优于2％,全场处理时间少于2分钟。