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91.
新型锂离子电池CaSnO_3负极材料的湿化学制备与电化学性能 总被引:1,自引:0,他引:1
采用湿化学方法合成了具有钙钛矿结构的CaSnO3,将其作为锂离子电池的负极活性物质,研究了其电化学性能。结果表明,湿化学方法制备的锡酸钙,粒度分布集中、平均粒径在500nm左右,在0 ̄1.0V之间以0.1C倍率充放电时,其可逆容量达到469mAh·g-1,而且循环性能良好。经80次循环后的容量衰减率只有0.57%。从首次放电容量和可逆容量来看,锡酸钙的储锂机制与锡基氧化物材料相似,即:首先是结构的还原并形成金属锡;然后金属锡与锂发生可逆的合金化与去合金化过程。锡酸钙的可逆容量、循环性能都比文献报道的块状锡氧化物或者是无定型锡基复合氧化物好,这说明钙钛矿结构和钙离子的存在可能对改善锡基负极材料的性能是有益的。 相似文献
92.
近年来,随着我国国民经济的快速发展和人们生活水平的提升,自驾游在全国旅游业中的比重逐渐增大.以旅游爱好者常住地——西安市为例,采用分步优化、聚类分析、蚁群优化算法、0-1规划、层次分析等数学方法,使得游览全国201个5A级景点的时间最短、费用最低、旅游体验度最优. 相似文献
93.
孙建新 《数学的实践与认识》2001,31(6):680-683
本文给出并证明了一个非完全图 G的最小 Hamilton回路必为最优旅行商路线的条件是除了应满足广义三角不等式外 ,还必须满足正则收缩性 相似文献
94.
The first step toward developing complete cell circuitry is to build quantitative networks for enzyme reactions. The conventional King-Altman-Hill (KAH) algorithm for topological analysis of enzyme networks, adapted from electrical networks, is based on “Reaction Graphs” that, unlike electrical circuits, are not quantitative, being straightforward renderings of conventional schematics of reaction mechanisms. Therefore, we propose the use of “Reaction Route (RR) Graphs” instead, as a more suitable graph-theoretical representation for topological analysis of enzyme reaction networks. The RR Graphs are drawn such that they are not only useful for visualizing the various reaction routes or pathways, but unlike Reaction Graphs possess network properties consistent with requisite kinetic, mass balance, and thermodynamic constraints. Therefore, they are better than the conventional Reaction Graphs for topological representation and analysis of enzyme reactions, both via the KAH methodology as well as via numerical matrix inversion. The difference between the two is highlighted based on the example of a single enzyme reaction network for the conversion of 7,8-dihydrofolate and NADPH into 5,6,7,8-tetrahydrofolate and NADP+, catalyzed by the enzyme dihydrofolate reductase. 相似文献
95.
96.
A New Route for Synthesis of Entecavir 总被引:3,自引:0,他引:3
Li Wei GUO Yuan Jing XIAO Li Ping YANG 《中国化学快报》2006,17(7):907-910
2-Amino-1,9-dihydro-9-[(1S,3R,4S)-4-hydroxy-3-(hydroxymethyl)-2-methylenecyclopen tyl]-6H-purin-6-one (entecavir, Scheme 1) is a novel carbocyclic 2-deoxyguanosine analog drug which has potent and selective anti hepatitis B virus (HBV) activity1-3. Entecavir is also effective against lamivudine-resistant YMDD mutants4. The US Food and Drug Administration (FDA) approved entecavir as a new preferred drug for the treatment of HBV after lamivudine in March, 2005. Scheme 1 The structure o… 相似文献
97.
《应用有机金属化学》2017,31(12)
The present study deals with the synthesis of CuO‐NPs via green route and investigated its application for removal of Cr(VI) from aqueous solutions. The experimental parameters were optimized through Box–Behnken Design (BBD) of response surface methodology for the optimum response. The adsorption equilibrium data was well fitted to Freundlich isotherm model and the kinetics was explained through pseudo‐second‐order kinetic model. The overall process was feasible, spontaneous and exothermic. Linear approach for analysing the isotherm as well as kinetic parameters was found more appropriate than the non‐linear approach. The adsorbent was successfully regenerated and reused up to five consecutive cycles without significant loss in removal capacity. The experimental results exhibited that CuO‐NPs can be a good alternative for Cr(VI) removal from aqueous solutions. 相似文献
98.
Qi Ji Yingchang Jiang Zhongping Zhang Yongtao Tian Zhenyang Wang 《无机化学与普通化学杂志》2014,640(10):1965-1970
A green route is designed to gain a clear idea of growth mechanism of complex VO2 (B) hierarchical microstructures, since this kind of metal oxide has various metastable phases due to their diverse valence states. Three‐dimensional (3D) uniform flower‐like VO2 (B) hierarchical microstructure has thus been assembled with the interleaving nanoplates, which are about 25 nm in thickness and well‐crystallized in structure with {114} planes as the dominant surfaces. Results of the systemic control experiments revealed that formation of the flower‐like VO2 (B) results from a fast nucleation‐growth process, where ethylene glycol (EG) not only acts as a green solvent and reductive agent, but also plays a key role in self‐assembly of the resulted VO2 (B) hierarchical microstructures. Hydroxyl amount on the solvent molecule is crucial in formation and shape control of VO2 (B) hierarchical microstructures. Result of this work would be helpful to understand the growth mechanism of complex three‐dimensional hierarchical superstructures of different metal oxides, which is very important to material science and inorganic synthetic chemistry. 相似文献
99.
Dendrimer chemistry is a fascinating and growing area of modern chemistry. Dendrimers are macromolecular entities with unique three-dimensional topologies, multi-functionality, and unique chemical and physical properties. Because of these characteristics, they are particularly well suited for applications in nanotechnology, pharmaceuticals, and medicinal chemistry. The study of dendrimers and hyperbranched polymers is gaining widespread interest from researchers in academia and industry for their unique structure and properties. This review article focused on dendrimer structure and the different synthetic strategies employed at the laboratory and commercial levels. This review covers convergent and divergent approaches, as well as accelerated approaches to dendrimer synthesis. 相似文献
100.
Nanocrystalline Ba2YZrO6‐dhas been successfully synthesized through a single step auto‐ignition combustion route. The samples were analyzed by powder X‐ray diffraction, transmission electron microscopy and Ultraviolet‐Visible spectroscopy. The XRD analysis revealed that the material has an ordered complex cubic perovskite structure. The basic optical properties and optical constants of the as‐prepared nanopowder of Ba2YZrO6‐dhave been reported for the first time. The spectral analysis revealed that the material is a wide band gap direct transition semiconductor with band gap of 3.70 eV at room temperature. The poor transmittance in ultraviolet but good transmittance in visible‐near infrared regions make the material potentially important for poultry protection and warming coatings, solar control, antireflection coatings and window layer in solar cells. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献