蒙药草乌花及其提取物化学成分的红外光谱法整体结构解析

采用傅立叶变换红外光谱法并借助于二阶导数谱以及二维相关红外光谱(2D-FTIR)研究了蒙药草乌花原药材及不同溶剂提取物(依次采用乙醚,乙醇和水提取)所含化学成分的红外谱图整体变化规律.结果显示:在草乌花原药材中具有明显的多糖类化合物的红外特征吸收峰,证明该药材中含有大量多糖类成分.草乌花药材乙醚和醇提物的红外光谱较相似...     

Experimental Solution of the Local Field Problem in Uniaxial Liquid Crystals†

A method of experimental determination of the Lorentz-factor tensor in uniaxial liquid crystals is suggested. The specific features of the local field tensor of the light wave in a nematic liquid crystal with low optical anisotropy have been investigated experimentally. Anisotropy of the local field and Lorentz-factor tensors has been found to decrease with the decreasing optical and molecular-optical anisotropies. These results appear to contradict the existing polarization theories of liquid crystals. The local field problem in cholesteric liquid crystals has been considered. A new approach to the local field problem in uniaxial liquid crystals with arbitrary optical anisotropy is developed and the experimental results are explained.     

Synthesis and Crystal Structure of Isosteviol Derivatives

Isosteviol (ent-16-ketobeyeran-19-oic acid, I) is a tetracyclic diterpenoid with a beyerane skeleton obtained by acid hydrolysis of stevioside.1 Several tetracyclic diterpenoids, specially the kaurenes, have important biological activities. Recent studies on the microbial transformation of isosteviol have revealed that it is metabolized by Cunninghamella bainieri, Actinoplanes sp., Mucor recurvatus, and Cunninghamella blackesleeana to yield five new metabolites.2 The hydroxylation pattern of these bioactive compounds may influence their binding on to the receptors, as was proposed for the Rabdosia diterpenoids. Therefore, the introduction of hydroxyl groups or unsaturated bonds in saturated and non-hydroxylated diterpenoids, like isosteviol, may enhance existing properties or lead to new biological activities. Although some beyeranes have been subjected to biotransformations by fungi,4 there are few report in the literature related the chemical transformation of Isosteviol. In the present study, we try to develop the chemical transformation of isosteviol and other beyeranes in order to obtaining some bioactive compounds with beyerane skeleton. Seven isosteviol derivatives, Ⅱ-Ⅷ, were therefore synthesized and characterized. The X-ray crystal strcture of H(R = H) was also determined.     

不同基底对TiO2和SiO2薄膜的光学性能的影响

采用溶胶-凝胶法分别在K9玻璃、单晶硅和石英玻璃基底上制备了纳米TiO₂和SiO₂薄膜。利用SEM、UV-Vis及反射式椭圆偏振光谱仪对薄膜的微观结构及光学特性进行了表征和分析。结果表明:3种基底中, 单晶硅基底上TiO₂和SiO₂薄膜折射率最大;在非晶态K9玻璃和石英玻璃基底上TiO₂薄膜折射率和透光率差异较大;SiO₂薄膜在非晶态基底上折射率、透光率相近;3种基底上薄膜的折射率和消光系数都有随波长增大而减小的趋势, 同时Cauchy模型能较好的描述单晶硅基底上两种薄膜在400~800 nm波段的光学性能。     

Low Frequency Circular Polarized Soliton in a Ferromagnetic System Under a Strong Bias Magnetic Field

The derivative nonlinear Schrodinger equation for the low frequency circular polarized wave, propagating parallel to the bias magnetic field in a ferromagnetic system, is derived by the reductive perturbation expansion method.     

Analytical Results for the Critical Exponents of Fully Directed Levy Flights

In this paper we generalize the definition of Levy flight (LF). With the help of a useful definition for the critical exponents of LF by introducing the concept of cutoff steplength, we calculate analytically the exponents of FDLFs in arbitrary d dimensions, utilizing the generating function method.     

一种分析自由电子激光场的新量子方法

将固体理论中的LLP变换用于研究自由电子激光场的量了态,并求得了小信号增益,这种新方法简捷且有助于深入地探讨自由电子激光场的量子特性. 关键词：     

蛙峡核的视野区域对应投射和双眼反应

本文用玻璃微电极从黑斑蛙(Rana nigromaculata)左峡核细胞外记录了125个单位的视觉反应,并用钴染色法标记出101个电极尖端位置,以便重建峡核内的视野图。在所记录的单位中,80％对静止光点显示给光(ON)-撤光(OFF)反应,许多单位对通过其感受域的黑、白目标的运动有方向选择性。所有钴标记点都在核内,表明峡核本身是蛙视觉系统的一个局限部分。在峡核内有一个视野投射圈。整个对侧半视野和同侧半视野的鼻侧40°呈区域对应地投射到峡核上。核内的无细胞带是对侧半视野与同侧半视野的分界线,它的背侧是对侧视野代表区。上视野投射到核的嘴半部、尾半部的中央和内腹部分。下视野的代表在尾半部的背部和外侧部。在峡核里观察到15个双眼单位,其中13个主要被对侧眼兴奋,2个几乎同等地被两只单眼兴奋。标记成功的14个双眼单位主要位于峡核嘴半部的髓质内。     

高校图书馆书刊采访决策支持系统

在指出高校图书馆书刊采访科学决策重要性的基础上,分析影响书刊采访决策的基本因素,提出一种科学的书刊采访决策模式.建立了图书供应商选择、采购经费分配、书刊选购决策的数学模型,进而给出书刊采访决策支持系统的设计方案.该系统的应用可提高图书采访质量.     

瞬态光谱测试仪在烟火方面的应用

用３５０～１１００ｎｍ瞬态光谱测试仪对烟火药剂进行谱测试，分析碱金属和碱土金属在烟火药火焰光谱中的辐射波段，计算各红外烟火剂的稳身指数。