用于直接合成碳酸二甲酯的新型高活性催化剂 A Novel Highly Active Catalyst for the Direct Synthesis of Dimethyl Carbonate

 将CO2直接合成法和酯交换法相结合,通过超强碱的引入和催化剂的微粉化,制备了一种新型的负载于MgO表面的碱-金属盐路易斯酸双组分催化剂,实现了以CO2,甲醇和环氧丙烷为原料的碳酸二甲酯一步直接合成.     

Oxidation kinetics of timahdit and tarfaya moroccan oil shales

Organic matter evolution and kinetics of combustion of Tarfaya and Timahdit oil shales have been examined by thermogravimetry (TG) and by differential thermal analysis (DTA). An agreement is observed between both techniques where it was found that combustion of organic matter occurs in two steps. Kissinger's method applied on experimental results gives an activation energy of the same magnitude for the first step of both oil shales (103 kJ mol^–1) whereas the second is 148 kJ mol^–1 for Timahdit and 118 kJ mol^–1 for Tarfaya.The changes in specific surface area during thermal combustion of Timahdit and Tarfaya oil shales have been studied by thermogravimetric gas sorption balance and correlated with experimental results obtained on TG/DTA in air. For Timahdit oil shale oxidation products, specific surface areas calculated from nitrogen adsorption data shows a slight increase during the temperature domain of 280 to 430°C and after this temperature, they increase sharply. However, data obtained with Tarfaya oil shales shows a significant increase at the temperature of maximum oxidation of the first stage of combustion of organic matter.This revised version was published online in November 2005 with corrections to the Cover Date.     

Physicochemical and structural properties of bacteriostatic sulfonamides: Theoretical study

A theoretical study at the Hartree–Fock and density functional theory levels is performed on sulfonamide‐type bacteriostatic compounds with the aim to provide an insight into their structure–activity relationship. The basicity of the p‐amino group is analyzed by means of the proton affinities and the protonation energies, showing that molecules presenting bacteriostatic activity are less basic, i.e., they are characterized by larger protonation energies and smaller proton affinities. The acidity of the amide group is analyzed through the deprotonation energy. The results reveal that the more acidic molecules present a larger bacteriostatic activity. This result is also confirmed from a study of bond orders. A bond order analysis of the amide group suggests that the electron attracting group in these molecules is responsible for the increase in acidity. The charge of the SO₂ group is also shown to be affected by the presence of the electron attracting group and consequently related to the acidity of the molecules. A geometric analysis shows that structures in which the amino group is more coplanar with respect to the benzenic ring possess larger bacteriostatic activity. A conformational analysis of these molecules illustrates that active molecules have relatively larger torsion energy barriers. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 165–172, 2003     

错配核酸的研究进展

本文通过介绍多种错配核酸的结构及其热力学性质，详细地描述了非Watson-Crick配对核酸的最新进展。这方面的研究有利于阐明生物体内错配核酸的识别修复机理及核酸二级结构的预测，并为合理设计新的人工核酸修复酶提供了理论基础。     

Molecular Recognition of Nucleic Acid Bases in Water by Hydrogen Bonding of Poly(vinyldiaminotriazine)

Poly(2-vinyl-4,6-diamino-1,3,5-triazine) efficiently binds nucleic acid bases and nucleosides in water by using complementary hydrogen bonding. The binding activity decreases in the order: U, T > A C, G. The corresponding monomer shows virtually no activity, indicating a predominant role of polymer effect for the molecular recognition in water.     

COMPOSITION OF THE ESSENTIAL OIL OF Haplophyllum myrtifolium

The chemical composition of the essential oil ofHaplophyllum myrtifoliumBoiss., endemic to Turkey, was examined by GC/MS. Ninety-seven compounds were characterized with linalool (12.8%), -caryophyllene (10.3 %), and methyleugenol (5.9 %) as the main constituents.     

A novel indicator series for measuring pKa values in acetonitrile

A series of substituted azobenzene dyes was found to span a range of 8 pK_a units in acetonitrile. The UV absorption spectra of the dyes are responsive to protonation, changing in both absorption maximum and intensity. These characteristics make the dyes useful as indicators for the measurement of pK_a values of neutral organic bases that absorb in the visible region of the spectrum.     

以催化油浆窄馏分为添加剂的Al－MCM－41分子筛的合成

 采用阳离子表面活性剂十六烷基三甲基溴化铵为模板剂，以正硅酸乙酯为硅源，以硫酸铝为铝源，水热合成了以催化油浆窄馏分为添加剂的高比表面积Al－MCM－41介孔分子筛，并利用XRD，HREM，TG－DTA及N2吸附－脱附等测试手段对合成样品进行了表征．合成的Al－MCM－41分子筛的比表面积和孔体积分别达到1295m2／g和1．5cm3／g，其平均孔径为4．3nm．重点研究了Al－MCM－41分子筛结晶度、晶胞参数、比表面积、孔体积及平均孔径等结构性质随催化油浆窄馏分添加量及其组成的变化规律，并从合成机理上进行了解释．     

Composition of <Emphasis Type="Italic">Carlina acanthifolia</Emphasis> Root Essential Oil

The root of Carlina acanthifolia All. (Asteraceae) contained 1.0% of essential oil (expressed in g per 100 g of dried plant material). Using GC and GC/MS, nine components were identified (100% of total oil). The structure of benzyl 2-furylacetylene (carlina oxide), which is the principal component of the oil (91.5%), was spectrometrically identified. __________ Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 331–332, July–August, 2005.     

微波辅助提取-GC/MS联用分析苍耳子中油脂成分的研究

采用微波辅助提取-GC/MS联用分析苍耳子中的油脂成分.以V(环已烷):V(丙酮)=1:1为提取溶剂,优化了微波辅助提取的条件.以正二十烷为内标,鉴定出了13种油脂成分,各组分相对保留时间的相对标准偏差(RSD)小于0.15%,相对峰面积的RSD＜3.0%.对不同批次以及不同产地的苍耳子样品进行了对比研究.该方法可用于苍耳子的鉴定和质量控制.