糖类研究（XVI）：大环化合物Clemochinenoside—A前体的合成

近年来，人们发现许多含糖物质具有较强的生物活性，如许多大环内脂的糖单元具有抗菌及抗癌活性等［‘”j．糖缀合物的这些重要生物活性已引起人们的极大兴趣．铁线莲（威灵仙，Clematischi，；e。；sts（）sbeck）被广泛应用于治疗关节炎、关节痛、头痛及炎症等疾病．Clemochinenoside－A（玉）是从该植物根中分离得到的非常少见的大环内酯糖吉化合物［’j，为进一步研究其特殊结构和药理活性，我们对1进行了全合成．本文报道呈的前体化合物10的立体选择性合成．其关键步骤是6的立体选择性青化和9的位置选择性甲磷酸化反应．互结果与讨论…     

R13B1与R152a专用状态方程的研究

一、引言 表示流体P、V、T关系的专用状态方程是流体热物性研究最基础的工作,它是计算流体PVT性质及对实验数据进行内插外推及计算其导出热力性质(如焓、熵等)的工具,也是用来制作热物性图表的基础方程.一般对专用状态方程的要求应包括:1)能适用于宽广的参数范围及整个流体区域;2)不仅在计算PVT性质时精度高,而且能正确地描述其     

γ-Al2O3表面原位合成Ni-Al-CO3LDHs研究

Ni-Al-CO₃LDHs/γ-Al₂O₃have been prepared using an in-situ synthesis technique. NH₃·H₂O was chosen as activation agent of Al on the γ-Al₂O₃surface as well as precipitant. Ni-Al-CO₃LDHs/γ-Al₂O₃was synthesized by controlling the reaction conditions such as temperature, concentration of Ni²⁺ and initial pH. The crystalline structure, chemical composition and porous structure were characterized by means of XRD, FT-IR, TG-DTA, ²⁷Al MAS-NMR and N₂ adsorption-desorption. The resulting sample of Ni-Al-CO₃LDHs/γ-Al₂O₃possesses higher specific area and narrower pore distribution, in which Ni-Al-CO₃LDHs are located on the surface of γ-Al₂O₃and share the same Al-O bonds with the γ-Al₂O₃lattice. Finally a possible structural model was proposed to account for the porous characters of Ni-Al-CO₃LDHs/γ-Al₂O₃.     

用119Sn、121Sb及13C NMR研究无水SnCl4、SbCl5与Lewis碱的相互作用

无水SnCl₄及SbCl₅是典型的Lewis酸,是有机反应中常用的催化剂。它们的溶剂化热效应早已受到人们的关注,然而用NMR方法来研究它们的溶剂化作用至今未见报道。本工作用¹¹⁹Sn、¹²¹Sb及(13)C NMR考察了典型Lewis酸无水SnCl₄、SnCl₅与二十几种Lewis碱的相互作用,直接证实了Lewis酸碱反应为电子的授受过程。     

多核NMR在相图研究中的应用——NaCl-NH4Cl-H2O体系的23Na、14N NMR研究

In the present paper, preliminary application of NMR to phase diagram study was reported. A multinuclear NMR quantitative method was developed. NaCl- NH_4Cl-H_2O system was studied by ~(23)Na and ~(14)N NMR. It has been shown that the multinuclear NMR quantitative method has its advantages when studying systems of multi-components.     

浸渍液对MgO表面性质的影响

浸渍液对ＭｇＯ表面性质的影响蔡炳新（湖南大学化学化工学院，长沙４１００１２）毛建新郑小明（杭州大学催化研究所，杭州３１００２８）关键词浸渍液，氧化镁，表面性质，乙烷，氧化脱氢分类号Ｏ６４３近年来，甲烷氧化偶联催化剂一直是热门的研究课题．普遍认为Ｍｇ...     

3-甲基-5-苯砜基-3E-戊烯-1-醇的立体专一性合成

3-甲基-5-苯砜基-3E-戊烯-1-醇(1)是合成某些萜类化合物的重要中间体.它具有反式烯丙基苯砜基双键.Julia等曾报道用含砜基的环丙基醇的开环重排反应来实现这类化合物的立体选择性合成,但其开环前体不易得到.本文以4-羟基-2-丁酮(2)为起始原料,经4步反应立体专一性地合成了标题化合物1.合成路线短、操作简便、易于大量制备.合成路线用方程式表示如下:     

基于非平衡电桥原理的太阳能双轴跟踪系统的设计

基于非平衡电桥原理,设计出一种可以自动跟踪光线的太阳能双轴跟踪设备.该设备利用光敏电阻阻值随着光照强度变化而改变这一特征,通过非平衡电桥输出大小和方向随光强变化而改变的电流.电流经过光电耦合器和三极管放大后,再通过继电器来控制两部相互独立的水平控制角和高度控制角电机的正反转,巧妙地实现了设备自动跟踪光信号的这一"智能化...     

Decay vertex reconstruction and 3-dimensional lifetime determination at BESⅢ

This paper focuses mainly on the vertex reconstruction of resonance particles with a relatively long lifetime such as Ks^0, A, as well as on lifetime measurements using a 3-dimensional fit. The kinematic constraints between the production and decay vertices and the decay vertex fitting algorithm based on the least squares method are both presented. Reconstruction efficiencies including experimental resolutions are discussed. The results and systematic errors are calculated based on a Monte Carlo simulation.