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   6900篇
  免费   378篇
  国内免费   52篇
电工技术   133篇
综合类   25篇
化学工业   1659篇
金属工艺   118篇
机械仪表   211篇
建筑科学   277篇
矿业工程   5篇
能源动力   461篇
轻工业   722篇
水利工程   76篇
石油天然气   115篇
无线电   652篇
一般工业技术   1139篇
冶金工业   337篇
原子能技术   83篇
自动化技术   1317篇
  2024年   19篇
  2023年   144篇
  2022年   244篇
  2021年   400篇
  2020年   294篇
  2019年   335篇
  2018年   416篇
  2017年   357篇
  2016年   355篇
  2015年   236篇
  2014年   319篇
  2013年   642篇
  2012年   356篇
  2011年   505篇
  2010年   350篇
  2009年   326篇
  2008年   288篇
  2007年   217篇
  2006年   201篇
  2005年   140篇
  2004年   111篇
  2003年   117篇
  2002年   90篇
  2001年   64篇
  2000年   73篇
  1999年   50篇
  1998年   77篇
  1997年   41篇
  1996年   49篇
  1995年   40篇
  1994年   36篇
  1993年   44篇
  1992年   35篇
  1991年   30篇
  1990年   28篇
  1989年   16篇
  1988年   30篇
  1987年   26篇
  1986年   20篇
  1985年   14篇
  1984年   25篇
  1983年   21篇
  1982年   21篇
  1981年   16篇
  1980年   19篇
  1979年   14篇
  1978年   16篇
  1977年   11篇
  1976年   13篇
  1975年   19篇
排序方式: 共有7330条查询结果,搜索用时 15 毫秒
991.
Scientometrics - This research letter discusses whether Arab Spring explains the changes in research productivity and impact of Arab countries by identifying non-sociopolitical factors that can be...  相似文献   
992.
Food Science and Biotechnology - Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver disorders. Possible links have been recently found between the gut-microbiota and the host...  相似文献   
993.
994.
995.
Thermoelectric generator, which converts heat into electrical energy, has great potential to power portable devices. Nevertheless, the efficiency of a thermoelectric generator suffers due to inefficient thermoelectric material performance. In the last two decades, the performance of inorganic thermoelectric materials has been significantly advanced through rigorous efforts and novel techniques. In this review, major issues and recent advancements that are associated with the efficiency of inorganic thermoelectric materials are encapsulated. In addition, miscellaneous optimization strategies, such as band engineering, energy filtering, modulation doping, and low dimensional materials to improve the performance of inorganic thermoelectric materials are reported. The methodological reviews and analyses showed that all these techniques have significantly enhanced the Seebeck coefficient, electrical conductivity, and reduced the thermal conductivity, consequently, improved ZT value to 2.42, 2.6, and 1.85 for near-room, medium, and high temperature inorganic thermoelectric material, respectively. Moreover, this review also focuses on the performance of silicon nanowires and their common fabrication techniques, which have the potential for thermoelectric power generation. Finally, the key outcomes along with future directions from this review are discussed at the end of this article.  相似文献   
996.
Multimedia Tools and Applications - For many vision applications, robust detection and tracking of pedestrians in image sequences are essential. In this paper, a hybrid system for pedestrian...  相似文献   
997.
International Journal of Information Security - When dealing with cloud services, there are important security requirements that are highly recommended to be achieved, notably, access control....  相似文献   
998.
In this paper, waste clay was cured with ethyl acetate to obtain treated clay(TC), which was modified with gallic acid to obtain a low-cost sorbent that was characterized by EDX, SEM, and FTIR analysis. Uranium(Ⅵ) adsorption was achieved using the batch adsorption method on the TC and gallic acid-modified treated clay(GMTC). The maximum uptakes of U(Ⅵ) on TC and GMTC were 37.2 and 193.0 mg/g, respectively.The U(Ⅵ) adsorption kinetics on the TC and GMTC sorbents were well-fitted by the pseudo-second-order mechanism, and the adsorption equilibrium followed the Langmuir model. The optimum parameters were applied to El Sela leach solution for uranium recovery.  相似文献   
999.
1000.
The effect of an electromagnetic field (EMF) on the rate of copper(II) cementation from copper sulfate solutions on a rotating iron cylinder was investigated. The studied variables were cylinder rotation speed, magnetic field strength, and magnetic field direction. The application of EMF increased the rate of cementation in both parallel and perpendicular direction of the magnetic field where the latter proved to be more effective. The rate of mass transfer under an EMF was found to be more than doubled. The enhancement of copper recovery in presence of the EMF is due to the induced motion of Fe+n in the solution which is limited to a certain range of cylinder rotation speed. The power consumption for cementation of copper could be significantly reduced by utilizing EMF.  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