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   19133篇
  免费   970篇
  国内免费   136篇
电工技术   325篇
综合类   32篇
化学工业   4197篇
金属工艺   597篇
机械仪表   643篇
建筑科学   370篇
矿业工程   47篇
能源动力   1374篇
轻工业   1187篇
水利工程   149篇
石油天然气   84篇
武器工业   1篇
无线电   2390篇
一般工业技术   4386篇
冶金工业   1455篇
原子能技术   175篇
自动化技术   2827篇
  2024年   78篇
  2023年   418篇
  2022年   963篇
  2021年   1162篇
  2020年   917篇
  2019年   950篇
  2018年   1241篇
  2017年   971篇
  2016年   945篇
  2015年   608篇
  2014年   852篇
  2013年   1531篇
  2012年   899篇
  2011年   1081篇
  2010年   864篇
  2009年   822篇
  2008年   726篇
  2007年   582篇
  2006年   478篇
  2005年   372篇
  2004年   277篇
  2003年   248篇
  2002年   194篇
  2001年   179篇
  2000年   173篇
  1999年   170篇
  1998年   292篇
  1997年   244篇
  1996年   221篇
  1995年   172篇
  1994年   158篇
  1993年   153篇
  1992年   103篇
  1991年   130篇
  1990年   101篇
  1989年   96篇
  1988年   79篇
  1987年   90篇
  1986年   76篇
  1985年   88篇
  1984年   75篇
  1983年   72篇
  1982年   61篇
  1981年   70篇
  1980年   48篇
  1979年   32篇
  1978年   27篇
  1977年   26篇
  1976年   35篇
  1971年   12篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
911.
912.
913.
914.
Journal of Mechanical Science and Technology - In this article, a new flow restrictor is utilized in the magnetorheological miniature gear-profile polishing (MRMGPP) method to ensure a consistent...  相似文献   
915.
Communication systems are needed to integrate generated power from wind farms with the electrical grid. This paper provides a comprehensive review of available communication technologies, protocols and objectives related to wind energy and electrical grid integration. This paper summarizes the communication system solutions for wind generation. A major obstacle is an absence of unified communication architectures and standards.  相似文献   
916.
India is one of the largest growing economies in the world. It has a GDP of 2487.94 billion US dollars as of 2017. Around 61.297% of power generation is by utilising abundantly available lignite blended with imported coal. India is slowly cutting out its demand for imported coal from other countries. It has built its own lignite-based power plant to overcome the need of imported coal. The impact on cost of electricity (COE) and net power output (NPO) after retrofitting carbon capture and storage (CCS) over a lignite-based power plant of India is analysed. In this paper, a feasibility study is carried out for NLC India Ltd Barsingsar power plant by retrofitting CCS. The results obtained from the Integrated Environmental Control Model (IECM) Software are positively strong enough to encourage CCS implementation. Various strategies for utilising the CO2 capture and carbon storage sites are suggested.  相似文献   
917.
Motorisation and fast depletion of fossil fuel reserves and issues like global warming have led the researchers all over to look for substitute fuels. Biodiesel resulting from vegetable oil is being used around the globe to lessen air pollution and reduce the necessity of diesel fuel. The current study covers the various aspects of N20 neem biodiesel with increased fuel injection pressure. The blends of N20 were tested with increased fuel injection pressure to examine the characteristics such as brake thermal efficiency, fuel consumption, emission and combustion parameters. Experimental results indicated that N20 with 240?bar has a closer performance to diesel, reduced exhaust emission and improved combustion parameters.  相似文献   
918.
This article presents experimental results of the effect of methanol gasoline blends as alternate fuels for the spark ignition (SI) engine. As the cost of the gasoline is periodically increasing the quest for the alternative fuels are evolved with which the emissions are reduced along with improved engine performance. A set of experiments have been conducted to investigate the effect of gasoline methanol blends in methanol percentages of M5, M10 and M15 on the engine performance and emissions. A significant reduction in emissions is observed with methanol blends compared to the standard gasoline with improved engine performance and emission characteristics. The fuels blends ranging from M10 to M15 have been found suitable for reduced emissions and improved engine performance.  相似文献   
919.
Studies are presented for the control of time-dependent effects of creep and shrinkage in steel-concrete composite frames with pre-cast concrete slab for both shored and un-shored constructions. A developed hybrid procedure has been used for carrying out the studies. The procedure accounts for creep, shrinkage and progressive cracking in concrete slab panels. Two frames, a single storey and a five storey frame are considered. It is shown that, for both the types of constructions, shored and un-shored, the increase in bending moments and mid-span deflections can be controlled to a significant degree, without putting constraints on design parameters, by simply delaying the time of mobilization of composite action between the pre-cast concrete slab panels and the steel section. It is also found that though there is insignificant effect of type of construction on bending moments, the percentage change in mid-span deflection due to creep and shrinkage is significantly higher for shored construction.  相似文献   
920.
The electrochemical treatment (ECT) of textile wastewater was carried out in a 1.5 dm3 electrolyte batch reactor using iron electrodes. With the four plate configurations, a current density (CD) of 89.2 A/m2 and a pH value of 8.5 were found to be optimal, at which maximum reduction in chemical oxygen demand (COD) and colour achieved were 86% and 79%, respectively. Loss of 0.0666 kg/m3 iron electrode and 18.44 kWh/m3 power consumption was observed during ECT with a maximum COD reduction of 79%. The settling characteristics of electrochemically treated effluents as well as the characteristics of foam and residue were also analysed.  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