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981.
采用火焰原子吸收法对30例男性型秃发患者及38例毛发健康男性对照者发中宏量元素K、Na、Ca、Mg的含量进行了测定。结果表明,男性型秃发患者发K含量明显高于对照组,具有统计学上的显著差异(P〈0.01)。发Na、Ca、Mg含量在两组间未见显著差异(P〉0.05)。本文提示,体内某些宏量元素变化对男性型秃发可能产生一定影响。 相似文献
982.
G. Ortega Zarzosa S. A. Palomares Sánchez J. R. Martánez Facundo Ruiz M. G. Sánchez-Loredo 《Journal of Sol-Gel Science and Technology》2005,35(1):5-11
Composites containing Pd aggregates dispersed in amorphous silica are of interest from both a fundamental and applied point of view because of their attractive catalytic properties. The silica powders added with palladium, prepared by the sol-gel method, were studied using X-ray diffraction, and IR- and UV-Vis-spectrophotometry. Silica xerogel samples were prepared using a ethanol/H2O/TEOS molar ratio of 4:11.6:1 and loaded with sodium tetrachloropalladate. The silica xerogel microstructure of the powders was studied as a function of annealing temperature. Attention was paid to the evolution of the glass matrix as well as the palladium aggregates in the SiO2 matrix. We found in our samples partial crystallization of the glass matrix in form of quartz and cristobalite phases with palladium oxide and metallic palladium phase at 1000∘C. The Rietveld refinement method was used in order to determine the percentage of the phase contents. 相似文献
983.
将钛酸四丁酯和硬脂酸在熔融状态下混合均匀后置于冷水浴中,使其凝固成凝胶,通过控制烧结过程中氧气的含量,成功地制备出粒度均匀、介电性能好的纳米晶TiO2.通过采用X射线光电子能谱和表面光电压谱对纳米晶TiO2表面状态的分析发现,材料表面存在大量的氧空位缺陷,暴露在粒子表面上的主要是一些金属Ti4+.纳米材料的这种表面状态对其极化性质具有重要的影响,使其在接近静态条件下的低频介电常数远大于常规材料的介电常数. 相似文献
984.
A portable chip-CE system with potential gradient detection (PGD) was developed and applied to the determinations of alkali metals and alkaloids. The separation efficiency appeared to be satisfactory and nonaqueous capillary electrophoresis (NACE) proved to be applicable to PGD or conductivity detection. The power supplies, separation and detection were built on a device of 3 kg in weight. A branch channel near the end of the separation channel was designed to perform PGD and make the application of relatively high field strength possible. The study is the first report on the application of PGD on the microchip platform. The design of the chip-CE system shows several advantages, such as simplicity, miniaturization and wide applicability. 相似文献
985.
Chen T Wang L Jiang G Wang J Dong X Wang X Zhou J Wang C Wang W 《The journal of physical chemistry. B》2005,109(10):4624-4630
The electrochemical behavior of poly(ferrocenyldimethylsilane-b-dimethylsiloxane) (PFDMS-b-PDMS) films deposited on a glassy carbon electrode was investigated by means of cyclic voltammetry (CV). The influences of the solvent, film thickness, temperature, and PDMS block length in PFDMS-b-PDMS on the electrode process were discussed. It was found that in 0.1 M aqueous LiClO(4) the electrochemical processes of the films on a glassy carbon electrode were complex and have a low rate of electron transport and mass diffusion. The kinetic parameters obtained indicated that the electrode process was controlled by both the electrode reaction and mass diffusion. 相似文献
986.
987.
The Raman scattering on a novel liquid crystal side chain polymer, poly-2,5-bis (p-meth-oxybenzoyloxy) styrene, has been performed. We observed that the characteristic Raman sp-ctra of the vinyl group in the monomer changed much deeply in the polymer, especially for the Raman line correponding to the C=C of the vinyl group which disappeared completly in the polymer. Contrast with that, the Raman spetra of the rest group did not present any substantial difference between the monomer and the polymer. These experimental facts show-ed that the vinyl group of the monomer was tranfered to the polymeric backbone while the chemical structure of the mesogenic unit in the monomer remained after the polymerization,and also conformed that it was successful in the synthesis of a liquid crystal side chain plymer without a flexible spacer between the mesomorphic unit and the molecular main chain. 相似文献
988.
Jun Zhang Kaimin Liu Gengmei Xing Tongxiang Ren Shukuan Wang 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(3):605-609
Gd@C82(OH)40 has been developed as a new generation of MRI contrast agent. But recently, it was found that Gd@C82(OH)
x
with a larger number of OH (x>36) would lead to cage break and hence, release of highly toxic Gd ions. We synthesized the more stable Gd@C82(OH)
x
with less OH-number, Gd@C82(OH)16, and studied its proton relaxivity and MRI images. The results indicate that Gd@C82(OH)16 also gives high proton relaxivity, even higher than that of (NMG)2-Gd-DTPA. The bio-distribution indicated that Gd@C82(OH)16 tends to be entrapped in the liver and kidney and remained in tissue for about 2 hours. The results suggest that the more
stable metallofullerene derivative Gd@C82(OH)16 can be the potential candidate of the new MRI contrast agent. 相似文献
989.
990.
以TiO2为载体,N iB为诱导剂,粉末化学镀法制备了负载型纳米N i催化剂.通过TEM、HRTEM、XRD和ICP技术对催化剂物性进行了表征.结果表明,碱性镀液可使载体表面均匀负载微晶结构纳米N i团簇,尺度为35nm左右.该负载型纳米N i在对氯硝基苯选择加氢反应中表现出很高催化加氢活性,并能有效抑制脱氯,达到了工业骨架镍水平.由酸性镀液得到的负载型非晶态纳米N i-P合金具有较弱的催化对氯硝基苯加氢活性.反应温度对反应时间和脱氯率有明显影响. 相似文献