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   654篇
  免费   25篇
  国内免费   5篇
电工技术   19篇
综合类   2篇
化学工业   128篇
金属工艺   13篇
机械仪表   18篇
建筑科学   14篇
矿业工程   2篇
能源动力   16篇
轻工业   45篇
水利工程   9篇
无线电   68篇
一般工业技术   194篇
冶金工业   77篇
原子能技术   9篇
自动化技术   70篇
  2024年   5篇
  2023年   8篇
  2022年   14篇
  2021年   26篇
  2020年   23篇
  2019年   27篇
  2018年   27篇
  2017年   24篇
  2016年   14篇
  2015年   11篇
  2014年   25篇
  2013年   47篇
  2012年   30篇
  2011年   38篇
  2010年   27篇
  2009年   30篇
  2008年   28篇
  2007年   27篇
  2006年   27篇
  2005年   31篇
  2004年   10篇
  2003年   15篇
  2002年   16篇
  2001年   7篇
  2000年   8篇
  1999年   5篇
  1998年   10篇
  1997年   10篇
  1996年   12篇
  1995年   12篇
  1994年   9篇
  1993年   6篇
  1992年   5篇
  1991年   11篇
  1990年   2篇
  1989年   10篇
  1988年   6篇
  1987年   6篇
  1986年   4篇
  1985年   2篇
  1984年   3篇
  1983年   6篇
  1982年   6篇
  1981年   2篇
  1976年   1篇
  1973年   3篇
  1972年   1篇
  1971年   2篇
  1970年   1篇
  1968年   1篇
排序方式: 共有684条查询结果,搜索用时 312 毫秒
31.
Cu-SiC nanocomposite coatings have been deposited from an aqueous sulfate electrolyte using the technique of pulse reverse electrodeposition both in the absence and presence of three different types of surfactants, anionic, cationic, or nonionic. The effects of different electrodeposition parameters on some properties of the coatings have been studied. In all cases, it has been observed that the surface roughness, hardness, and resistivity increase with the increase in cathodic current density. However, they have been observed to decrease with the increase in anodic current density and the anodic current time. The variation in the amount of incorporated reinforcement with different deposition parameters has been observed to be dependent on the nature of the surfactant used. In the presence of cationic and nonionic surfactant, a noticeable increase in the amount of incorporated reinforcement and hardness has been observed. Samples prepared under higher anodic current density have been observed to possess lower stress, but intense texture. An increase in cathodic current density has been observed to decrease the extent of texturing.  相似文献   
32.
The by-products of zinc refineries are used as the primary mineral resources for the commercial production of indium. The discarded LCDs containing adequate amount of indium is rather worth as its secondary resources compared to the by-products of zinc refineries. Mining and recycling rates of indium, respectively from minerals and waste LCDs are in progress to meet its huge demand. Recycling of the LCDs has been dominating over mining, as presently 480t of indium are produced annually from mining, however, that of 650t annually from recycling. Different aspects of the extractive metallurgy of indium are summarized in this review paper.  相似文献   
33.
Aluminum was electrodeposited from two different ionic liquid electrolytes namely; 1-ethyl-3-methylimidazolicum chloride and AlCl3 (EMIC–AlCl3) and 1-butyl-3-methylimidazolium chloride (BMIC–AlCl3) at 90 ± 2 °C. Nodular morphology of aluminum was obtained at the copper substrate. To evaluate the reaction mechanism, chronoamperometric study was adopted. From the chronoamperometric analysis, it was observed that the reaction was controlled by instantaneous three-dimensional diffusion process. The diffusion coefficient (D) of Al2C7 was found to be 5.2–6.6 × 10−11 m2 s−1 and 2.2 × 10−11 m2 s−1 for EMIC–AlCl3 and BMIC–AlCl3 ionic liquid electrolytes, respectively. The nuclei density of electrodeposited aluminum on the copper was also confirmed by scanning electron microscope wherein uniformly distributed aluminum nodules were observed.  相似文献   
34.
35.

This paper investigates the combined effect of actuator saturation and time-delay on load frequency control (LFC) of a wind-integrated power system (WIPS). Actuator saturation is represented in two different approaches such as polytopic and sector bounding. Delay-discretization-based sliding mode \(H_{\infty }\) control approach is proposed to design a novel LFC scheme. The proposed control scheme requires present as well as delayed states information as input to the controller. This requirement of control scheme is fulfilled by adopting a finite known delay. This finite known delay used in controller design is discretized into delay intervals. Lyapunov–Krasovskii functional is defined for each delay interval, and \(H_{\infty }\) stabilization criteria for the closed loop WIPS are derived in linear matrix inequality framework using Wirtinger-based inequality. The proposed control scheme is tested by considering a numerical example of two-area WIPS.

  相似文献   
36.
37.
Water Resources Management - Accurate prediction of shear stress distribution along the boundary in an open channel is the key to solving numerous critical engineering problems such as flood...  相似文献   
38.
Multimedia Tools and Applications - Traditional Content-Based Image Retrieval (CBIR) systems were developed for retrieving similar kinds of images from a whole image database based on the given...  相似文献   
39.
40.
Chloride induced reinforcement corrosion in concrete is a serious durability problem. Different sources of chloride, i.e. chloride introduced at the fresh stage of concrete (i.e. internal chloride) and chloride entered during the hardened state (i.e. external chloride) may affect the performance of concrete in different ways. For the performance evaluation of reinforced concrete in chloride environment (i.e. both internal and external chloride), there is a need for performing different electrochemical tests to obtain various corrosion parameters that will specify the possibility and the magnitude of corrosion in concrete. In the present study, the results of an experimental investigation that includes different corrosion tests namely potential measurement, corrosion rate measurement and potentiodynamic polarization test have been presented and analyzed to evaluate the performance of concrete both in internal chloride and external chloride exposure conditions. In addition an attempt is made to correlate the corrosion parameters obtained from internal and external chloride exposure conditions. From the results it was observed that, dropped half-cell potential value obtained from external chloride exposure mostly lie in the active zone obtained from internal chloride exposure. In addition it was observed that there was significant difference in corrosion current values obtained from both internal and external chloride exposure conditions. Further on the basis of overall ranking obtained from the results of critical parameters from different exposure conditions, the performance of different cement–steel combinations against chloride induced rebar corrosion has been evaluated.  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