全文获取类型
收费全文 | 831篇 |
免费 | 5篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 48篇 |
综合类 | 15篇 |
化学工业 | 299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 |
出版年
2023年 | 11篇 |
2022年 | 18篇 |
2021年 | 28篇 |
2020年 | 24篇 |
2019年 | 26篇 |
2018年 | 24篇 |
2017年 | 23篇 |
2016年 | 15篇 |
2015年 | 14篇 |
2014年 | 25篇 |
2013年 | 46篇 |
2012年 | 28篇 |
2011年 | 99篇 |
2010年 | 71篇 |
2009年 | 72篇 |
2008年 | 53篇 |
2007年 | 56篇 |
2006年 | 37篇 |
2005年 | 23篇 |
2004年 | 28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847条查询结果,搜索用时 31 毫秒
141.
142.
无机添加剂对铅蓄电池充放电过程的影响 总被引:1,自引:0,他引:1
何刚 《化学工业与工程技术》1998,(1)
通过充放电曲线法研究无机添加剂对铅蓄电池充放电过程的影响。研究发现,硫酸钠添加剂对恒电流放电容量的影响分为两个阶段,在循环初期使电池放电容量增大,但在循环后期使放电容量减小;硫酸镉添加剂使电池在恒电流条件下放电容量增大;硫酸铍和硫酸铵在整个循环过程中均使放电容量减小。 相似文献
143.
A three‐dimensional numerical model of the polymer electrolyte fuel cell (PEFC) is applied to study current distribution and cell performance under a current density boundary condition. Since the electronic resistance in the along‐channel direction in the current collector plate is much larger than in the other two directions, i.e., 50 mΩ cm2 vs. 0.5 mΩ cm2, it significantly affects current flow, and current and cell voltage distributions in a PEFC. An identical polarization curve results with two different boundary conditions, constant cell voltage and constant current density, however, the current density profiles in the along‐channel direction differ significantly; it is much flatter for the constant current boundary condition. Increasing the electronic conductivity of the bipolar plate diminishes the difference in the current density distribution under the two boundary conditions. The results also point out that an experimental validation of a PEFC model based on the polarization curve alone is insufficient, and that detailed current density distribution data in the along‐channel direction is essential. 相似文献
144.
Kevin L. Gering 《Electrochimica acta》2006,51(15):3125-3138
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
145.
Sara Paydar Nabeela Akbar Quan Shi Yan Wu 《International Journal of Hydrogen Energy》2021,46(15):9927-9937
The interfacial properties of electrolyte materials have a crucial impact on the ionic conductivity of solid batteries and solid oxide fuel cells. Here we construct cuprospinel CuFe2O4 (CFO)–ZnO composite as a functional electrolyte for fuel cell device. In an optimal composition of 0.3CFO-0.7ZnO electrolyte fuel cell, the maximum power output of 675 mW cm?2 is obtained at 550 °C. The electrical properties and electrochemical performance are strongly dependent on the ratios between CFO and ZnO in CFO-ZnO composite. Notably, surprising fuel cell performance with high ionic conductivity is attained by constructing this p-type CFO composited with n-type ZnO. Proton conduction was further verified experimentally. The interfacial ionic conduction pathway between the two constituent phases plays a vital role to enhance the proton conductivity, and the bulk p-n heterojunction can block internal electronic pass. An excellent current and power densities of CFO-ZnO composite are observed along with a high conductivity of 0.35 S·cm-1 at 550 °C. This work opens a new perspective for the semiconductor materials that can widely be developed for electrolytes, based on their tunable band structure. 相似文献
146.
《Ceramics International》2022,48(24):36469-36477
Sr11Mo4O23(SMO) material has a double-layer perovskite superstructure, which exhibits unusual structural flexibility and oxygen ion mobility. However, the Sr11Mo4O23 cubic phase will transform into SrMoO4 tetragonal phase at 400 °C, which leads to a sharp decrease in conductivity. In order to solve this problem, Ta doped Sr11Mo4-xTaxO23-δ (SMTO, 0 ≤ x ≤ 1.25) electrolytes were synthesized by a route combining the Pechini method and solid-state reaction. The effects of acceptor-type Ta5+ doping on the structural stability, micro-scale structure and ionic conductivity of SMO are characterized by X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, and electrochemical impedance spectroscopy. All Sr11Mo4-xTaxO23-δ powders are single-phase and no secondary phase is detected. Moreover, the phase transition of Sr11Mo4O23 to SrMoO4 is highly inhibited by partially replacing Mo with Ta (x ≥ 0.50) during the heat treatment, and the Sr11Mo4O23 cubic phase with high conductivity may be maintained for a long time at 800 °C. The total ionic conductivity of Sr11Mo4-xTaxO23-δ samples increases with increasing the Ta concentration, and then declines at higher doping content (x = 1.25). The ionic conductivity of Sr11Mo3TaO23-δ (SMTO100) pellet is the highest, reaching 1.44 × 10?2 S/cm at 800 °C. More remarkably, the conductivity of STMO100 pellet remains at its peak during the 100 h annealing test at the temperature of 800 °C. 相似文献
147.
《Ceramics International》2022,48(18):26476-26486
In this paper, the influence of Bi/Zn mass ratio on the phase composition, microstructure, sintering properties, and electrical properties of Bi/Zn co-added Nd0.2Ce0.8O1.9 (NDC) used for intermediate-temperature solid oxide fuel cells (SOFCs) was investigated. At 700 °C, the total conductivity of the NDC-based electrolyte (3Bi/1Zn-NDC) with the mass ratio 3:1 for Bi2O3 and ZnO was as high as 5.89 × 10?2 S cm?1, 4.60 and 4.51 times higher than the single addition of 4 wt% Bi2O3 and 4 wt% ZnO, respectively. In addition, the 3Bi/1Zn-NDC electrolyte exhibited a good physical and chemical compatibility with the electrode materials. The open circuit voltage (OCV) of the cell supported by the 3Bi/1Zn-NDC electrolyte was 0.67 V, and the output power density could reach 402.25 mW cm?2 at 700 °C. It showed stable power output and OCV in the long-term stability test within 50 h. Overall, the combination of 3 wt% Bi2O3 and 1 wt% ZnO was a very effective dual sintering aid for NDC electrolyte. 相似文献
148.
《International Journal of Hydrogen Energy》2022,47(21):11279-11287
Bismuth oxide and scandia co-doped zirconia (Sc2O3)0.06(Bi2O3)x(ZrO2)0.94–x (ScSZB, x = 0, 0.01, 0.03, 0.05, 0.07, 0.1) powders are prepared via a citrate sol-gel method. Bi2O3 promotes the sintering process of scandia stabilized zirconia (ScSZ) and increases electrical conductivity of system. A high conductivity of ~0.094 S/cm at 800 °C is achieved on 5 mol% Bi2O3 doped ScSZ (ScSZB05). X-ray Rietveld refinement and transmission electron microscope (TEM) analysis of the ScSZB05 reveal the formation of cubic phase and rhombohedral phase at room temperature. The electrolyte-supported cell constructed by the ScSZ electrolyte gives the maximum power density of 258.3 mW/cm2 at 800 °C, while the cell with ScSZB05 electrolyte shows a higher value of 387.6 mW/cm2. The performance obtained by theoretical simulation of the two electrolyte-supported cells is in good agreement with the experimental results. 相似文献
149.
《Calphad》2018
Advances in thermodynamic equilibrium have led to the recent development of binary, ternary and quaternary systems including electrolytes. However, a precise determination of phase equilibrium must consider the physical-chemical aspects of the components that will can to take place in a mixture. A solute is liable to dissociate hence the need to take this consideration into account. The chosen organic acids have attracted much attention in the research works but unfortunately, their dissociation into the aqueous phase has not been taken into the calculation of phase equilibrium. The present research work focuses on the development of the calculation of the phase equilibrium methods by including the dissociation of the chosen organic acids, for predicting the liquid-liquid equilibrium (LLE) data from the binary parameters for various ternary systems composed of {water-phosphoric acid-methylisobutylketone},{water-acetic acid-cumene},{water-propionic acid-cumene},{water-formic acid-isoamyl acetate} and {water-butyric acid-isoamyl acetate} at 298.15 K and normal atmospheric pressure, so as to be able to design electrolytes having specific properties. This requires a modeling framework that is based upon the fundamental laws and models of physics. Therefore, in our study, we used the Extended UNIQUAC model to predict the LLE data. We are newly investigating the effect of including the dissociation of the picked organic acids on prediction of phase equilibrium. The results have been compared with authors who consider no dissociation of organic acids, where they have been satisfactory. 相似文献
150.
Bianca Lucas-Granados Rita Sánchez-Tovar Ramón M. Fernández-Domene José García-Antón 《International Journal of Hydrogen Energy》2018,43(16):7923-7937
Iron oxide nanostructures are an attractive option for being used as photocatalyst in photoelectrochemical applications such as water splitting for hydrogen production. Nanostructures can be obtained by different techniques, and electrochemical anodization is one of the simplest methods which allows high control of the obtained morphology by controlling its different operational parameters. In the present study, the influence of the electrolyte temperature during electrochemical anodization under stagnant and hydrodynamic conditions was evaluated. Temperature considerably affected the morphology of the obtained nanostructures and their photoelectrochemical behavior. Several techniques were used in order to characterize the obtained nanostructures, such as Field Emission Scanning Electron Microscopy (before and after the annealing treatment in order to evaluate the changes in morphology), Raman spectroscopy, photocurrent vs. potential measurements and Mott-Schottky analysis. Results revealed that the nanostructures synthesized at an electrolyte temperature of 25 °C and 1000 rpm are the most suitable for being used as photocatalysts for water splitting. 相似文献