雷公藤碱丁和碱辛的结构

从雷公藤中分离了二个生物碱: 碱丁(Wilfortrine)和碱辛(Neowilforine),用化学和光谱法测定了它们的结构, 碱辛是一种新生物碱.     

XPS研究Nd表面氧化物的生长过程

用X射线光电子能谱(XPS)研究新鲜Nd表面在不同氧气和空气进气量的情况下,表面氧化物的生长过程.发现氧化层由氧化物、氢氧化物及表面化学吸附水三种成分,这三种成分的增加与进气量都存在正比对数关系,氧化物和吸附水在一定进气量后趋于饱和,而氢氧化物持续不断增加,最终氢氧化物占据主要地位. 关键词： X射线光电子能谱(XPS) Nd 氧化     

UH和UH_2分子的结构与势能函数

用相对论有效原子实势 (RECP)和密度泛函 (B3LYP SDD)方法研究了UH ,UH2 基态和低激发态的结构和势能函数 ,导出了分子的光谱数据 .结果表明 ,UH和UH2 的基电子状态分别为X4 Π和X3A2 ,离解能分别为 2 .886eV和5 .2 4 9eV ,UH2 具有C2v对称性 ,得到了UH和UH2 的几个不同的低激发态的结构与光谱数据 .应用多体项展式理论以及数字拟合方法 ,计算得到了UH分子和基态UH2 三原子分子的分析势能函数 ,该函数正确反映了UH和UH2分子的结构特征 ,可用于研究UHH的微观反应动力学 .     

Anisotropy of Long-term Resistivity Relaxations Induced in p -(0 0 1)GaAs/Al 0.5 Ga 0.5 As by Uniaxial Stress

Anisotropy of the piezoresistance relaxations has been observed in p -(0 0 1)GaAs/Al 0.5 Ga 0.5 As heterostructures. The character of relaxation process depends on the direction of the applied uniaxial compression: after loading along [1 m 1 0] direction the specimen resistance relaxes down to the lower magnitude while after loading along [1 1 0] direction it relaxes up to the higher magnitude. Shubnikov-de Haas oscillations and Hall effect measurements indicate that variation of the carrier concentration j N in the quantum well during relaxation processes has different signs for uniaxial compression along [1 m 1 0] and [1 1 0] directions and correlates with the corresponding change of the resistance. The piezoelectric field that in GaAs can reach the magnitude E =1.152 2 10 6 V/m at uniaxial stress P =1 kbar along d 1 1 0 ¢ directions is supposed to be responsible for the metastable state after loading (unloading) and redistribution of carriers during the relaxation process.     

Induced absorption in yttrium aluminium perovskite crystals irradiated by 12C and 235U ions

The present work is devoted to investigation of optical absorption in pure and neodymium-doped YAlO₃ (YAP) single crystals in the spectral range 0.2–1.1 μm induced by the influence of ¹²C ions irradiation with energy 4.50 MeV/u (MeV per nucleon) and a fluence 2 × 10⁹ cm^?2 or of ²³⁵U ion irradiation with energy 9.35 MeV/u and a fluence 5 × 10¹¹ cm^?2. The induced absorption in the case of ¹²C ions irradiation is caused by recharging of point growth defects and impurities under the radiation influence. After irradiation by ²³⁵U ions with fluence 5 × 10¹¹ cm^?2 the strong absorption rise is probably caused by contribution of the lattice destruction as a result of heavy ion bombardment.     

First integrals and analytical solutions of the nonlinear fin problem with temperature-dependent thermal conductivity and heat transfer coefficient

Fin materials can be observed in a variety of engineering applications. They are used to ease the dissipation of heat from a heated wall to the surrounding environment. In this work, we consider a nonlinear fin problem with temperature-dependent thermal conductivity and heat transfer coefficient. The equation(s) under study are highly nonlinear. Both the thermal conductivity and the heat transfer coefficient are given as arbitrary functions of temperature. Firstly, we consider the Lie group analysis for different cases of thermal conductivity and the heat transfer coefficients. These classifications are obtained from the Lie group analysis. Then, the first integrals of the nonlinear straight fin problem are constructed by three methods, namely, Noether’s classical method, partial Noether approach and Ibragimov’s nonlocal conservation method. Some exact analytical solutions are also constructed. The obtained result is also compared with the result obtained by other methods.     

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...     

A Novel Divalent Ytterbium Complex Supported by a Bridged Diamide Ligand： Synthesis and Structure of [{Me2Si（NPh ）2Yb（THF）2}（μ3-CI）（μ4-CI）{Li（TH F） }2]2·2THF

The reaction of anhydrous YbCl3 with 1 equiv, of Li2Me2Si（NPh）2 in THF, after workup, yielded a ytterbium（Ⅲ） chloride [{Me2Si（NPh）2Yb}（μ2-CI）（TMEDA）]2·3PhMe （1） （TMEDA=tetramethylethanediamine）. The same reaction followed by treatment with Na-K alloy afforded a new ytterbium（H） complex supported by a bridged diamide with four coordinated LiC1 molecules, [{Me2Si（NPh）2Yb（THF）2}（μ3-CI）（μ4-CI）{Li（THF）}2]2·2THF （2） in high yield. Both complexes were structurally characterized by X-ray analysis to be dimers. Complex 1 was a chlorine-bridged dimer with ytterbium in a distorted octahedral geometry. In complex 2 two [Me2Si（NPh）2Yb（THF）2]- （μ3-CI）[Li（THF）]2 moieties were connected with each other by two μ4-CI bridges to form a ＂chair-form＂ framework.     

Microdetermination of the amine oxide group in organic compounds by reduction with titanium(III)

A rapid and selective method for the determination of water-soluble boron in complex fertilizers is described. Boron is separated from the sample solution, which should be approximately 0.1 N in hydrochloric acid, by shaking twice with 20% solution of 2-ethyl-1,3-hexanediol in hexone. Following this extraction boron is back-extracted into the aqueous phase with 0.5 N sodium hydroxide. It is finally determined spectrophotometrically at 415 nm using azomethine H as reagent.     

Identification and semiquantitative estimation of phosphate,silicate, arsenate and germanate by the ring-oven method

A general ring-oven procedure was developed for the detection of phosphate, silicate, arsenate or germanate based on the molybdate-benzidine test. Procedures are also described for the simultaneous detection of these anions in mixtures, by means of organic masking agents. A semi-quantitative method is described for the estimation of the four anions; the ring colours of sample solutions are compared with those of standard solutions. Colours obtained from phosphate are stable if the rings are covered with a film of paraffin wax. A preliminary calibration scheme against phosphate is necessary for the other anions because of colour instability. The maximum error found was ±6.35% while the total average error was ±4.3%.