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1.
C60系列结构,制备分离方法与性质的研究进展   总被引:2,自引:1,他引:1  
本文综述地评述了C60的结构,制备分离方法,及其衍生物表现出的异常的物理、化学性质,其碱金属盐呈现导电性或超导性、铁磁性、光学非线性、耐磨擦性能等。为进一步研究C60及其衍生物提供了信息。  相似文献   

2.
Cryoscopic measurements have been carried out on solutions in sulfuric acid of a heterocyclic polymer, its monomers, and certain of its oligomers. The polymer, BBB, is prepared by the polycondensation of 1,4,5,8-naphthalenetetracarboxylic acid (NTC) with 3,3′-diaminobenzidine (DAB). The results show that the polymer, its oligomers and one of its monomers, DAB, are all extensively protonated in sulfuric acid, whereas its other monomer is not. The degree of protonation appears to be greater for the polymer than for its low molecular weight oligomers.  相似文献   

3.
A simple rapid, accurate, and reliable method of simultaneous determination of arsenic, germanium, phosphorus, and silicon is reported. The method involves first, the determination of germanium as its phenlfluorone complex and its selective extraction with isoamyl alcohol. Phosphorus is next determined as its heteropoly blue after selective extraction of phosphomolybdic acid by isobutyl acetate at pH 1.0-0.8 and its direct reduction in this solvent. Silicon is then determined after its extraction as silicomolybdic acid by isooctyl alcohol at pH < 0.4 and direct reduction in the solvent phase. Finally, arsenic is determined in the remaining aqueous phase after reduction to its heteropoly blue.  相似文献   

4.
Interest in zirconia as a chromatography support has increased considerably recently because of its chemical inertness and its promise as a useful support. We have reported the preparation of spherical zirconia and characterization of its chromatographic behavior. However, the zirconia was found unsatisfactory for its chromatographic efficiency, probably owing to the poor pore structure of it. In this paper, we for the first time report the preparation of alkylphosphonic acid modified zirconia-magnesia stationary phase, and characterization of its structure and chromatographic behavior.  相似文献   

5.
Corsini A  Nieboer E 《Talanta》1973,20(3):291-303
The compound 2,2'-dimercaptodiethylsulphide has been investigated with regard to the stability of its solutions to air oxidation, its acid strength, its reactivity towards metal ions, the nature of its Ni(II) and Pd(II) complexes in solution, and its applicability to the determination of small amounts of Ni(II) and Pd(II). Studies on the Ni(II) complex extend the work reported previously by others and are not in complete accord with it. The results presented show that 2,2'-dimercaptodiethylsulphide is a promising analytical reagent.  相似文献   

6.
The bioanalysis of the oral anticancer drug capecitabine and its metabolites has been investigated extensively over the past years. This paper reviews methods for the bioanalysis of capecitabine and its metabolites. The focus of this review will be on sample pre-treatment, chromatography and detection. Furthermore, the choice of standards and analytical problems encountered during analysis of capecitabine and its metabolites in biological matrices will be discussed. The major challenges in the bioanalysis of capecitabine and its metabolites are the simultaneous extraction and analysis due to the differences in polarity of the analytes. Furthermore we evaluate currently described methods for the quantification of capecitabine and its metabolites. Future wishes and perspectives are stated that could serve as an inspiration for further development of assays for the quantification of capecitabine and its metabolites.  相似文献   

7.
微量元素硒与生物体健康   总被引:9,自引:1,他引:8  
从硒在生物体内的分布、存在形态及代谢,硒的生物学功能,硒缺乏及硒中毒,生物体日需要量等方面阐述了硒与生物体健康的关系。  相似文献   

8.
Summary We developed an automated, two-column HPLC-method that can be used routinely to quantify the catecholamines norepinephrine and epinephrine in body fluids. The method is based on a new, laboratory-prepared SEC-HPAC column material, on the application of a microprocessor-controlled column-switching technique, and on the use of an integrated reaction system for postcolumn derivatization and trihydroxyindol-fluorescence monitoring. It allows the direct injection (upto 500 μl) of an appropriate biological fluid and distinguishes on its integrated sample-processing mode, its practicability, its chemoselectivity and-specivity, its detection limit (2 pg), its within- and between-run precision and its speed of analysis.
  相似文献   

9.
The Sturmian transformation is reviewed and some of its properties are discussed, in particular, its use in perturbative approaches, its connection with variational schemes, and its use for the study of resonances. One potential problem (Doolen) having no bound states is described exactly.  相似文献   

10.
The principal information needs of chemists in the pharmaceutical industry center around a substance, methods used for its characterization, its reactions, its physicochemical and biomedical properties, and its metabolic fate in biological media. Novelty searches for a specific chemical are critical because of the need for patent protection for product candidates. Chemical relatives are important, necessitating substructure searching. Therapeutic neighbors may give insight into its biological mode of action. The phases of drug discovery and development are used to indicate the diversity of the information needs of chemists and to emphasize the dual process of generation and use of information.  相似文献   

11.
Simmons A 《Ambix》2006,53(3):221-236
In 1672, a laboratory was founded by the Society of Apothecaries at its premises in Blackfriars, London, to manufacture chemical medicines. By exploring the society's motivations for constructing a laboratory and its development during the eighteenth century, this paper examines the roles that chemistry played within the activities of the institution. While the chemistry's primary utility was in drug manufacturing for the society's pharmaceutical trade, through its laboratory, the society used chemistry to develop its corporate and educational aims, thus helping to secure its institutional authority in London's medical marketplace.  相似文献   

12.
在INDO/CI方法的基础上,预测B32及其包心化合物的电子结构与光谱,并与其共轭多面体C40及其包心化合物进行对比。  相似文献   

13.
Nigricanoside A was isolated from green alga, and its dimethyl ester was found to display potent cytotoxicity. Its scarcity prevented a full structure elucidation, leaving total synthesis as the only means to determine its relative and absolute stereochemistry and to explore its biological activity. Here we assign the stereochemistry of the natural product through enantioselective total synthesis and provide initial studies of its cytotoxicity.  相似文献   

14.
明胶/胶原因其优良的理化性质和生物学性能而在生物材料、食品包装等方面得到了广泛的应用,但其热稳定性差、机械强度低、水汽阻隔性能差等缺点限制了它的应用,因此在很多应用场合需要对明胶/胶原进行交联改性处理。本文主要综述了近年来国内外对明胶/胶原进行共混和化学交联改性以及物理改性的研究进展,并对其作用效果进行了分析。  相似文献   

15.
生物高分子液晶的新家族——甲壳素及其衍生物   总被引:11,自引:0,他引:11  
董炎明  袁清 《高分子通报》1999,(4):48-56,33
讨论了生物高分子甲壳素及其衍生物形成液晶态的基本结构条件。简要介绍了为制备液晶性甲壳素衍生物所必须的一些主要的化学修饰途径。综述了十几年来甲壳素衍生物(主要是壳聚糖及其衍生物)液晶性的研究进展。介绍了甲壳素及其衍生物的液晶纺丝及其应用前景。指出甲壳素衍生物已成为纤维素之外生物高分子液晶的一个新的大家族。  相似文献   

16.
为进一步阐明癌组织与宏量、徽量元素的关系.用原子吸收光谱法测定胃癌、大肠癌、乳腺癌组织及其癌旁组织和同体正常组织中铬、锰、锌、铁、镁、铜和钙的含量.试找这些元素在癌、癌旁及其同体正常组织中的分布规律.测定结果;在胃癌组织中锌的含量比癌旁组织、同体正常组织少。铜的含量比正常组织多。其余五种元素的含量在这三个组织之间比较无明显差异;在大肠癌组织中锰、镁的音量比癌旁组织多.其他五种元素的含量在这三个组织之间比较,无明显差异;在乳腺癌组织中铬,锰和铁的含量比正常组织多。锌、镁、钙的含量比同体正常组织和癌旁组织多,铜的含量在这三个组织中比较无明显差异,总之,胃癌、大肠癌及乳腺癌组织及其癌旁组织和同体正常组织中。上述七种元素的音量是不同的。特别是在乳腺癌组织中除铜以外的六种元素的含量都比正常组织多.值得进一步研究.  相似文献   

17.
The molecular structure and properties of 7-azaindole in its first four singlet states were studied with a view to improving current understanding of the photophysical behavior of its C(2h) dimer. This dimer, which exhibits a double proton transfer via its two hydrogen bonds upon electronic excitation, has for 35 years been used as a model for the photophysical behavior of DNA base pairs. Electronic excitation of 7-azaindole simultaneously increases its acidity and basicity; these changes facilitate a concerted mechanism for the double proton transfer in the dimer. In this work, we found the acidity and basicity changes to occur only in its first pi,pi(*) excited singlet state.  相似文献   

18.
侯晨  朱浩  李亦婧  李彦锋 《化学进展》2012,(9):1729-1741
脯氨酸及其衍生物作为有机手性催化剂,在不对称有机合成中得到广泛应用。该类催化剂具有结构简单、来源丰富和选择性高等优点,但仍存在催化剂用量大、难以回收以及无法重复利用等不足。近年来,随着固定化技术的发展,固定化脯氨酸及其衍生物受到广泛关注。固定化脯氨酸及其衍生物催化剂可以简化不对称催化中产物的分离过程,实现催化剂的便利回收与循环使用。本文综述了固定化脯氨酸及其衍生物的制备及在催化不对称有机合成(如Aldol反应、Michael加成反应、Mannich反应等)中的研究进展。  相似文献   

19.
This article presents remarks on the meaning of stopping power and of its magnitude. More precisely, the first set of remarks concerns the connection of stopping power with elements of particle-transport theory, which describes particle transport and its consequences in full detail, including its stochastic aspects. The second set of remarks concerns the magnitude of the stopping power of a material and its relation with the material's electronic structure and other properties. © 1996 John Wiley & Sons, Inc.  相似文献   

20.
Camptothecin (CPT) and its hydroxycamptothecin analogs are fluorescent compounds exhibiting strong anticancer properties. They exist in two forms: active lactone and inactive carboxylate. The deactivation proceeds via hydrolysis in neutral and base solutions. A serious limitation to the clinical application of CPT is the strong affinity of its carboxylate form to human serum albumin (HSA) which destabilizes its active lactone form. However, binding to membranes in blood improves the stability of the lactone form of CPT and its analogs. A high-throughput screening assay based on the steady-state fluorescence anisotropy method was used to determine the protein- and membrane-binding properties of 10 hydroxycamptothecin (10-OH-CPT), 7-ethyl-10-hydroxycamptothecin (SN-38) and 7-tert-butyldimethylsil-10-hydroxycamptothecin (DB-67). The relative affinities of hydroxycamptothecins to HSA and model membranes in the form of DMPC liposomes were determined, and DB-67 exhibited the most desirable properties including the highest affinity to membranes in its lactone form and low affinity to HSA in its carboxylate form.  相似文献   

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