Studies on Silicon-Containing Fragrance Raw Materials (Ⅳ)——Synthesis of Spiro-Acetals of 5-Trimethylsilylcyclohex- 2- (or 3)enone

Some novel spiro-acetals of 5-trimethylsilylcyclohex-2(or 3)-enone were synthesized from the reaction of silylcyclohexenones with the corresponding a, ω-diols in the presence of oxalic acid or adipic acid.     

CRYSTAL STRUCTURE INVESTIGATION OF VANADYL COMPLEXES OF TRIDENTATE LIGAND (Ⅰ)——THE CRYSTAL STRUCTURES OF BIS[(1-(2,4-PENTANE- DIONATO(NITROBENZOYL) HYDRAZONE)-2- ETHOXY)OXOVANADIUM] AND BIS-[(1-(2, 4-PENTANEDIONATO-(3-NITROBENZOYL) HYDRAZONE)-2- METHO

The title complexes were obtained by the reactions of bis(2,4-pentanedionato)oxovanadium VO(Acac)_2 and m-nitrophenylhydrazide m-NO_2PhCONHNH_2 in the media EtOH and MeOH respectively. The compound (Ⅰ) crystallizes in the space group PT with unit cell dimensions a=8.123(2), b=10.409(5), c=10.822(4), α=65.78(3)°, β=85.50(3)°,γ=89.04(3)°. The compound (Ⅱ) crystallizes in the space group P2_1/a with unit cell dimensions a=7.745(2), b=19.164(5), c=10.787(4), β=107.87(2)°. The resuhs of structural analyses show that the two compounds have the same characteristics: the tridentate ligand formed by condensation occupies three of the four equatorial positions of vanadium and the rest equatorial position is occupied by alkoxy group RO~-. As RO~-group also bridges the sixth coordinated position of each vanadium atom, it brings about the formation of the new type binuclear complexes of vanadium.     

Fe-Cr-Co永磁合金的高温X射线衍射研究

本文用高温X射线粉末衍射法研究了成分为(重量百分比)62Fe-23Cr-15Co的可加工永磁合金热处理条件与晶体结构的关系。对高温淬火后只经过时效的样品,以及经过淬火、磁场热处理和时效的样品摄取了高温德拜·谢乐相,观察了高温相变的差异,测量了时效样品点阵常数随温度的变化。我们发现:只经过淬火和时效的样品在610℃左右出现一新的过渡相(X相)。 关键词：     

GaP(N,Te,Zn)的静压光致荧光研究

对GaP(N,Te,Zn)样品做了77K的静压光致荧光研究。得到了N,NN₁,NN₃束缚激子能级的压力系数,以及施主Te和中性施主Te的束缚激子能级的压力系数。讨论了这些能级随压力的变化行为,并首次观察到Gap中自由激子的零声子发射。 关键词：     

表面复合速度对于锗的光电导光谱分布的影响(二)

The continuity equation of minority carriers in n-type germanium is solved for the stationary case, in which the volume recombination is assumed to be of the recombination-center type and the surface recombination is introduced in the boundary condition. An expression for the photoconductivity is obtained from this solution.By substituting the known absorption data and the volume lifetime of minority carrier in the sample into the expression of photoconductivity and by choosing suitable values of surface recombination velocity, photoconductive spectra are calculated and are compared with the experimental curves. The agreement is satisfactory for wave-lengths greater than 1.2 μ. Below 1.2 μ, the experimental curves fall well below the calculated curves. It is thought that other types of volume recombination may exist.The photoconductive spectra usually have a maximum outside the absorption edge. By measuring the relative height of the maximum, the surface recombination velocity can be obtained. This method is suitable for medium and large values of surface recombination velocity.The photoconductivity drops sharply on both sides of the maximum in case of large values of recombination velocity. In such cases, the energy gap of the semiconductor can be obtained in a simple way. For germanium the energy gap is 0.83 eV for direct transition and 0.635 eV for indirect transition.From this investigation, the energy gap of CdS is reestimated to be 2.53 eV and that of Cu₂O greater than 2.10 eV.     

松弛模型中的液气共存平衡态

对密闭的一维有限长管道里的等温相变．研究了松弛模型中液气共存平衡态的稳定性．使用匹配渐近展开形式上推出了一阶扰动满足的线性系统．理论分析发现．初始小扰动通常会被耗散掉,然而在一些特殊情况下,它们会维持在一定的水平上．数值计算也表明了松弛机制对相变演化具有稳定作用．     

薄膜测厚仪

许多物理实验要用很薄的膜,如薄靶、薄吸收片、薄窗等,并且要知道所用薄膜的厚度(或面密度)。测量薄膜厚度的方法有称重方法、光学方法、电学方法和放射性方法等。这些方法适用于测量不同厚度的薄膜,准确度也不同。我们制备了一台简便的α粒子薄膜测厚仪,并且用它测量了厚度从10微克/厘米~2到数百微克/厘米~2的VYNS有机薄膜的厚度(VYNS是氯乙烯和醋酸乙烯的共聚物)。     

大花无柱兰遗传多样性的SRAP标记分析

大花无柱兰是一种珍稀兰科植物,具有一定的观赏和药用价值,但数量十分稀少,该物种亟待保护。本研究采用SRAP分子标记技术,对10个居群的115份DNA样品进行PCR扩增,并开展遗传多样性分析。从81对引物中筛选出9个条带清晰、多态性好、重复性高的引物组合,共扩增得到305条谱带。在物种水平上,多态性比率（PPB）为100%,Nei’s基因多样性指数（H）为0.209 8,Shannon’s指数（I）为0.340 2;在居群水平上,PPB为24.59%～52.13%,H为0.079 6～0.165 5,I为0.120 9～0.252 3。居群水平上,基因分化度（Gst）为0.520 9,基因流（Nm）为0.459 9,遗传距离为0.091 9～0.198 4。UPGMA聚类结果表明,10个居群可分为3大类,地理距离相近的居群优先聚集。大花无柱兰的遗传多样性较为丰富,居群间存在一定的遗传分化和基因交流,可采用就地保护和人工栽培等方式加以保护。     

伊辛模型的四分支临界面及其临界行为

本文通过等标度同普适类变换理论,使严格的重正化群递推方程得以直接应用。对伊辛模型的计算产生了四个不动点、四支临界面。对应于铁磁及反铁磁相变,其结果与已知的严格解及最好近似解一致。对于超反铁磁相变,本文提出临界曲面方程为—ch(h)=sh(2K_x)sh(2K_y)。 关键词：     

溶液中向列型液晶有序度以及外场对它们的影响

根据Lebwohl-Lasher模型以及平均场近似得到了存在于外场中的溶液中向列型液晶分子有序度参数的自洽方程.无外场时,溶液中液晶发生一级相变,不同浓度相转变时2>均为0.324,T^N1与浓度成正比,T_φ^N1=T_φ=1^N1φ。而存在外场时,液晶发生二级相变,且都发生于2>=0.40处.液晶分子取向分布曲线为V型,均方偏差随2关键词：