全文获取类型
收费全文 | 37637篇 |
免费 | 4445篇 |
国内免费 | 2463篇 |
专业分类
电工技术 | 16074篇 |
综合类 | 3089篇 |
化学工业 | 2130篇 |
金属工艺 | 2186篇 |
机械仪表 | 1901篇 |
建筑科学 | 1269篇 |
矿业工程 | 944篇 |
能源动力 | 1011篇 |
轻工业 | 538篇 |
水利工程 | 789篇 |
石油天然气 | 560篇 |
武器工业 | 290篇 |
无线电 | 6694篇 |
一般工业技术 | 2105篇 |
冶金工业 | 1233篇 |
原子能技术 | 604篇 |
自动化技术 | 3128篇 |
出版年
2024年 | 162篇 |
2023年 | 465篇 |
2022年 | 740篇 |
2021年 | 1004篇 |
2020年 | 1072篇 |
2019年 | 843篇 |
2018年 | 846篇 |
2017年 | 1333篇 |
2016年 | 1421篇 |
2015年 | 1581篇 |
2014年 | 2458篇 |
2013年 | 2108篇 |
2012年 | 2880篇 |
2011年 | 3145篇 |
2010年 | 2344篇 |
2009年 | 2565篇 |
2008年 | 2464篇 |
2007年 | 2957篇 |
2006年 | 2568篇 |
2005年 | 2088篇 |
2004年 | 1682篇 |
2003年 | 1414篇 |
2002年 | 1179篇 |
2001年 | 1028篇 |
2000年 | 917篇 |
1999年 | 672篇 |
1998年 | 507篇 |
1997年 | 408篇 |
1996年 | 377篇 |
1995年 | 289篇 |
1994年 | 239篇 |
1993年 | 165篇 |
1992年 | 161篇 |
1991年 | 107篇 |
1990年 | 86篇 |
1989年 | 72篇 |
1988年 | 43篇 |
1987年 | 36篇 |
1986年 | 22篇 |
1985年 | 18篇 |
1984年 | 25篇 |
1983年 | 17篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1962年 | 2篇 |
1959年 | 4篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
传统的水面流速流向测量多采用经纬仪交会法,此法需要大量的人力和设备,工作量大且费时。近几年,随着全球定位系统(GPS)的广泛应用和实践,在一定范围内,采用GPS定位法替代经纬仪交会法施测水面流速流向。介绍了GPS定位法的测量原理、设备,以及测量方法。通过对GPS定位法的精度和优缺点的分析,得出采用GPS定位法施测水面流速流向具有较高的推广价值。 相似文献
83.
In this paper, we present an approach toward pedestrian detection and tracking from infrared imagery using joint shape and appearance cues. A layered representation is first introduced and a generalized expectation-maximization (EM) algorithm is developed to separate infrared images into background (still) and foreground (moving) layers regardless of camera panning. In the two-pass scheme of detecting pedestrians from the foreground layer: shape cue is first used to eliminate non-pedestrian moving objects and then appearance cue helps to locate the exact position of pedestrians. Templates with varying sizes are sequentially applied to detect pedestrians at multiple scales to accommodate different camera distances. To facilitate the task of pedestrian tracking, we formulate the problem of shot segmentation and present a graph matching-based tracking algorithm that jointly exploits the shape, appearance and distance information. Experimental results with both OSU Infrared Image Database and WVU Infrared Video Database are reported to demonstrate the accuracy and robustness of our algorithm. 相似文献
84.
A. Demoz C. Khulbe C. Fairbridge S. Petrovic 《Journal of Applied Electrochemistry》2008,38(6):845-851
Hydrogen is among the emerging energy vectors that are being developed to replace nonrenewable hydrocarbon energy sources.
The preferred method to produce hydrogen without generating greenhouse gases is the electrolysis of water using renewable
energy. The reduction of energy during the water electrolysis process is a desirable goal regardless of the source of electric
power. Similar to ferrous/ferric mediation, iodide can be used as a mediator in the electrolysis of an acidic suspension of
coke or coal. The iodide ion is oxidized at a far lower anodic potential than the alternative oxygen evolution reaction. This
reduces the cell electrolysis voltage and, consequently, reduces electricity use. The iodide consumed at the anode is continuously
regenerated by chemical reaction with the coke/coal in suspension. 相似文献
85.
针对贵溪冶炼厂建安公司新紫杂铜打包机不良状况及存在的问题进行了改进 ,对整台机组的总配电箱、液压管网、设备的保护接地及建筑主体框架也进行接地。 相似文献
86.
We present the fabrication and short circuit test results of a 14 kV single-phase resistive superconducting fault current limiter (SFCL) based on YBa2Cu3O7 (YBCO) films. Individual components were processed using the 4″ YBCO films and have the rated voltage and current of 600 V and 35 A at 77 K, respectively. Twenty four components, eight components in series and three lines in parallel, make a module having the rated voltage and current of 4.8 kV and 105 A, respectively. Three modules were assembled in series to produce the SFCL working at 77 K, a 14 kV single-phase machine for the 22.9 kV Y-Y grid. short circuit tests were successfully conducted in an accredited test facility with the maximum fault currents up to 14.1 kAP. All components quenched together upon faults and shared the rated voltage evenly without any supplementary device between the modules. This proves that the SFCL based on YBCO films may not only work reliably at 22.9 kV, but also provide technical feasibility for higher voltage application including the transmission grids. 相似文献
87.
A method of current drive with Ion Cyclotron Range of Frequency (ICRF) on Experimental Advanced Superconducting Tokomak (EAST) is described. A variety of liquid silicon oil heights in the phase shifter will bring the phase difference to the current drive. It is found that the current drive can be achieved by using the phase shifter. The liquid phase shifter is one of the impedance matching systems too. 相似文献
88.
Collinear magnetooptic interaction with magnetostatic surface waves (MSSW) can be used for wavelength‐selective switches, wavelength filters, and frequency shifters in wavelength‐division‐multiplexed (WDM) photonic networks and optical processing systems. The switching efficiency can be improved with a multilayer waveguide structure. To investigate the dynamic switching characteristics, the FDTD method was employed. The mode conversion between TE and TM mode was successfully demonstrated with FDTD simulation. The filtering characteristics were also evaluated. The FDTD results were compared with the result from the coupled mode theory, and good agreement was obtained. Switching of an optical pulse was also demonstrated by the FDTD method. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 40–47, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20501 相似文献
89.
90.
桥丝电阻分布的均匀性对发火电流的影响 总被引:2,自引:0,他引:2
文中分析了桥丝电阻分布的均匀性对电雷管发火电流的影响,并对试验结果作了分析和讨论。 相似文献