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211.
Nanocrystalline Mo2C powders were successfully synthesized at 500 °C by reacting molybdenum chloride (MoCl5) with C (graphite or carbon nanotube) in metallic sodium medium. X-ray powder diffractometer (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscope (XPS) and surface area analyzer (BET method) were used to characterize the samples. Experiments reveal that the carbon source used for the carbide synthesis has a great effect on the particle size and the surface area of the samples. When micro-sized graphite was used as C source the obtained nanocrystalline Mo2C powder consists of particles of 30∼100 nm, with a surface area of 2.311 m2/g. When carbon nanotubes were used as C source, the as-synthesized Mo2C sample is composed of particles of 20∼50 nm, with a surface area of 23.458 m2/g, which is an order of magnitude larger than that of the carbide prepared from the graphite. 相似文献
212.
Yuchuan Zhang Jiasheng Qian Zhuo KeXiangcheng Zhu Hong BiKangming Nie 《European Polymer Journal》2002,38(2):333-337
The intermolecular interactions between poly(vinyl chloride) (PVC) and poly(vinyl acetate) (PVAc) in tetrahydrofuran (THF), methyl ethyl ketone (MEK) and N,N′-dimethylformamide (DMF) were thoroughly investigated by the viscosity measurement. It has been found that the solvent selected has a great influence upon the polymer-polymer interactions in solution. If using PVAc and THF, or PVAc and DMF to form polymer solvent, the intrinsic viscosity of PVC in polymer solvent of (PVAc+THF) or (PVAc+DMF) is less than in corresponding pure solvent of THF or DMF. On the contrary, if using PVAc and MEK to form polymer solvent, the intrinsic viscosity of PVC in polymer solvent of (PVAc+MEK) is larger than in pure solvent of MEK. The influence of solvent upon the polymer-polymer interactions also comes from the interaction parameter term Δb, developed from modified Krigbaum and Wall theory. If PVC/PVAc blends with the weight ratio of 1/1 was dissolved in THF or DMF, Δb<0. On the contrary, if PVC/PVAc blends with the same weight ratio was dissolved in MEK, Δb>0. These experimental results show that the compatibility of PVC/PVAc blends is greatly associated with the solvent from which polymer mixtures were cast. The agreement of these results with differential scanning calorimetry measurements of PVC/PVAc blends casting from different solvents is good. 相似文献
213.
S.H. LiuX.F. Qian J. YinL. Hong X.L. WangZ.K. Zhu 《Journal of solid state chemistry》2002,168(1):259-262
Ag2S nanoparticles in hyperbranched polyurethane matrix were prepared through the in situ reaction with thioacetamide as the sulfur source at room temperature. Transmission electron microscopic analysis revealed a uniform spherical shape for Ag2S nanoparticles, with an average size of about 4-10 nm and a narrow size distribution. X-ray powder diffraction and UV-vis spectroscopy were also used to characterize the obtained nanoparticles 相似文献
214.
Shen Chao-Hong Bao Bo-Rong Wang Gao-Dong Qian Jun Bao Ya-Zhi Cao Zheng-Bai 《Journal of Radioanalytical and Nuclear Chemistry》1992,162(2):207-216
Extraction of uranium(VI), thorium(IV) from nitric acid has been studied with N-octylcaprolactam and N-(2-ethyl)hexylcaprolactam. Distribution coefficients of U(VI), Th(IV) and HNO3 as a function of aqueous NHO3 concentration, extractant concentration and temperature have been studied. The compositions of extracted species, thermodynamic parameters of extraction have been evaluated. Third phase formation in extraction of U(VI) has been studied. Back extraction behavior of U(VI) and Th(IV) from the organic phase has also been tested. The results obtained are compared with those obtained by using TBP under the same experimental conditions. 相似文献
215.
QianWANG XuXU 《中国化学快报》2003,14(12):1278-1280
The mixtures of two polymers, poly (N,N-dimethylacrylamide) (PDMA) and polyvinylpyrrolidone (PVP) were synthesized and used as the separation medium for double-stranded and single-stranded DNA fragments by capillary electrophoresis with UV detector. On optimal conditions, 2%w/v PDMA 2%w/v PVP can be used to separate the doublet 123/124bp in pBR322/Hae Ⅲ Markers. 相似文献
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O/W微乳液中聚吡咯超微粒子的制备 总被引:4,自引:0,他引:4
选择合适的SDBS/吡咯/H2O三组分O/W微乳液与吡咯单体共存的两相体系,以单体相为单体源,在O/W三组分微乳液中进行了吡咯聚合,所得聚吡咯粒子大小仅为2~3nm,分布较均匀,且具有较好的导电性能. 相似文献
220.
基因工程技术已经成为研究和生产重组人血清白蛋白(rHSA)替代人血清白蛋白(HSA)的重点技术,而白蛋白的纯化则是该技术的关键。本文主要介绍了从转基因猪血中纯化rHSA的一种新方法,即热乙醇沉淀与多级色谱分离相结合的rHSA纯化方法。热乙醇沉淀法可从猪血浆中获得rHSA粗提取液,此时rHSA的纯度可达69.5%,回收率达51.3%。进一步采用多级色谱分离法,即阴离子交换色谱和反相色谱法进一步纯化,得到rHSA的最终纯度约为100.0%,总回收率为41.1%。该方法为从转基因猪血浆中大规模纯化用于临床和生化研究的高纯度rHSA提供可能,同时也为rHSA替代HSA奠定了基础。 相似文献