首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   764篇
  免费   6篇
  国内免费   10篇
电工技术   48篇
综合类   15篇
化学工业   232篇
金属工艺   44篇
机械仪表   22篇
矿业工程   8篇
能源动力   300篇
轻工业   12篇
石油天然气   1篇
无线电   19篇
一般工业技术   43篇
冶金工业   23篇
原子能技术   3篇
自动化技术   10篇
  2023年   11篇
  2022年   18篇
  2021年   28篇
  2020年   24篇
  2019年   26篇
  2018年   23篇
  2017年   23篇
  2016年   10篇
  2015年   10篇
  2014年   22篇
  2013年   31篇
  2012年   19篇
  2011年   91篇
  2010年   65篇
  2009年   66篇
  2008年   52篇
  2007年   54篇
  2006年   36篇
  2005年   21篇
  2004年   24篇
  2003年   11篇
  2002年   11篇
  2001年   11篇
  2000年   11篇
  1999年   8篇
  1998年   11篇
  1997年   2篇
  1996年   11篇
  1995年   9篇
  1994年   9篇
  1993年   8篇
  1992年   8篇
  1991年   9篇
  1990年   1篇
  1988年   1篇
  1987年   2篇
  1985年   1篇
  1982年   1篇
  1980年   1篇
排序方式: 共有780条查询结果,搜索用时 15 毫秒
91.
Electrolytes based on Sc2O3–ZrO2 exhibit the highest ionic conductivity of zirconia based systems, however, stabilization of the electrochemical properties at operational temperatures, 600–1000 °C, are needed before implementation into SOFCs. Trace additions of Bi2O3 are a known sintering aid for zirconia systems. Crystal structures, electrical properties and long-term stability of Bi2O3-doped 10ScSZ systems were investigated. The addition of more than 1.0 mol% Bi2O3 resulted in suppression of the rhombohedral to cubic phase transformation at 600 °C and cubic phase stabilization at room temperature. The ionic conductivity of 10ScSZ was also improved by Bi2O3 additions. A maximum conductivity of 0.034 S cm−1 at 700 °C was observed in 2 mol% Bi2O3-doped 10ScSZ sintered at 1300 °C. No phase change was observed in 10ScSZ after annealing at 1000 °C. A certain amount of monoclinic phase, and dramatic conductivity decrease, were observed in Bi2O3-doped samples sintered below 1200 °C after annealing. However, 10ScSZ and 2 mol% Bi2O3-doped 10ScSZ sintered at 1300 °C show no significant conductivity degradation with annealing. Samples with more than 1 mol% Bi2O3 and sintered above 1300 °C resulted in good ionic conductivity and stability.  相似文献   
92.
Five new ionic liquids of 1-vinyl-3-alkylimidazolium iodide were synthesized to develop novel electrolytes for dye-sensitized solar cells. The effects of photovoltaic characteristics of the cell and the ionic liquid features such as viscosity and ionic conductivity were described. The 1-vinyl-3-alkylimidazolium cation volume was calculated by quantum chemistry method. The linear dependence of photon-to-current conversion efficiency on the non-solvated cation volume was revealed. After lithium iodide was added to 1-vinyl-3-alkylimidazolium salts as electrolytes, except the photovoltage, the photocurrent, fill factor and photon-to-current efficiency were improved correspondingly.  相似文献   
93.
In this paper, we studied the influence of different cations on redox behavior of I and I3 by cyclic voltammetry and electrochemical impedance spectroscopy. It was demonstrated that increasing cation size tends to give rise to higher reductive activity of I and lower diffusion coefficient of I3 in these cations, alkylimidazolium, [Na ⊂ 15-C-5]+ and [K ⊂ 18-C-6]+. Moreover, we measured the performance of dye-sensitized solar cells (DSCs) with electrolyte containing [K ⊂ 18-C-6]I or 1,2-dimethyl-3-propylimidazolium iodide (DMPII). It was found that dye-sensitized solar cells (DSCs) with [K ⊂ 18-C-6]I give a little higher short-circuit photocurrent density and a little lower fill factor than DSCs with DMPII.  相似文献   
94.
Effects of the electrolyte of DSCs on impedance spectra were evaluated by changing concentration of redox couple, viscosity, and additives to electrolyte. The relation with current-voltage characteristics (I-V characteristics) was investigated. In many cases, the impedance component attributed to charge transfer at TiO2|electrolyte interface demonstrated strong relation with the I-V characteristics. The recombination of electrons in TiO2 with I3 in electrolyte was a key factor in determining performance of DSCs. To evaluate the effect of I3, diffusion-limiting current in the electrolyte for various viscosities was evaluated by cyclic voltammetry. When the short circuit current (SCC) was almost equal to the diffusion-limiting current, strong influence of the diffusion coefficient on the impedance spectra was observed: impedance arcs were enlarged as the diffusion coefficient was decreased. On the other hand, when the diffusion-limiting current was larger than the SCC, photo-excitation and electron injection processes became dominating factors in the DSCs performance. The SCC was regulated by the charge recombination process at TiO2|electrolyte interface, and thus the impedance component ω3 was related to the performance in such condition.  相似文献   
95.
Electrolyte viscosity is a macroscopic property, although its foundation lies on molecular-scale interactions between solvent and ionic species. A comprehensive understanding of viscosity behavior with respect to solvent composition, salt concentration and temperature is only possible with correct interpretations of molecular interactions and related quantities. This work introduces a new methodology for predicting electrolyte viscosity under a wide range of conditions, based on molecular, physical, and chemical properties. The general formalism is universal for aqueous and non-aqueous systems alike. Although the immediate application of the resultant model is candidate electrolytes for lithium ion batteries, other applications abound in the areas of industrial fluids, biological systems, and other electrochemical systems whose performance characteristics are tied to viscosity. Viscosity predictions are compared to experimental data for a number of electrolytes, demonstrating exceptional accuracy of predictions over wide temperature ranges and broad ranges of salt concentration.  相似文献   
96.
In the present study, are reported investigations obtained with the room temperature molten salt (RTMS) ethyl-methyl-imidazolium bis-(trifluoromethanesulfonyl)-imide (EMI-TFSI) in order to use it as solvent in lithium battery. The thermal stability, viscosity, conductivity and electrochemical properties are presented. A solution of 1m lithium bis-(trifluoromethanesulfonyl)-imide (LiTFSI) in EMI-TFSI has been used to test the electrolyte in a battery with LiCoO2 and Li4Ti5O12 as respectively cathode and anode materials. Cycling and power measurements have been obtained. The results have been compared with those obtained with a molten salt formulated with a different anion, BF4 and with a conventional liquid organic solvent EC/DMC containing LiTFSI. The 1m LiTFSI/EMI-TFSI electrolyte provides the best cycling performance: a capacity up to 106 mAh g−1 is still delivered after 200 cycles, with 1C rate at 25 °C.  相似文献   
97.
陈华  梁亚芹  丰磊 《电子质量》2004,(2):J013-J015
阐述了高频低阻抗长寿命铝电解电容器的特点,通过研制工作电解液、制订材料配套方案及工艺改进,研制出的高频低阻抗长寿命铝电解电容器产品性能与日本Nichicon公司PW系列产品相当,完全可以替代进口产品.  相似文献   
98.
Aqueous sodium oxalate (NaOX) solutions both without (1) and with (2) p-toluenesulfonic acid (p-TSA) were used to synthesize a poly(aniline-co-o-anisidine) (PANI-co-POA) film on mild steel (MS). Polarization of the substrate in p-TSA containing NaOX solution mixture led to the passivation of the surface mainly via the formation of an iron(II) oxalate layer. Copolymer coatings showed that p-TSA + NaOX solution mixture was a suitable medium for the deposition of a uniform, compact and strongly adherent PANI-co-POA coating on MS electrode. Similar coating was achieved when NaOX solution was used free of p-TSA. It was observed that addition of p-TSA in NaOX solution provided also an increase in electropolymerization rate. Evaluation of the anticorrosion performance of copolymer coatings in 3.5% NaCl solution was investigated by using AC impedance spectroscopy (EIS) technique and anodic polarization curves. Both copolymer coatings exhibited a significant physical barrier property against the attack of corrosive products on mild steel, in longer periods.  相似文献   
99.
从电解质溶液的经典理论、半经验模型和统计力学3方面综述了电解质溶液热力学性质的研究进展,并对各种理论和模型在理论与实践方面的局限性作了相关评述。从分子、离子角度对电解质溶液的热力学性质进行研究比较,探讨了其宏观热力学性质与微观结构的相关性。展望了电解质溶液热力学理论近期研究的热点和未来的发展方向。  相似文献   
100.
通过对不同电解液成分和浓度的选取,制备氧化和着色兼容的微弧氧化膜。不同种类的电解液所得到的微弧氧化膜层颜色也不同,同种体系中的主要成分浓度的不同是影响微弧氧化膜颜色和生成速率的原因之一。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号