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   111536篇
  免费   8329篇
  国内免费   4180篇
电工技术   5841篇
技术理论   11篇
综合类   6583篇
化学工业   18939篇
金属工艺   5801篇
机械仪表   6667篇
建筑科学   8625篇
矿业工程   3079篇
能源动力   3094篇
轻工业   6624篇
水利工程   1714篇
石油天然气   6216篇
武器工业   691篇
无线电   13955篇
一般工业技术   14221篇
冶金工业   5899篇
原子能技术   1237篇
自动化技术   14848篇
  2024年   431篇
  2023年   1748篇
  2022年   2877篇
  2021年   3974篇
  2020年   3044篇
  2019年   2582篇
  2018年   2984篇
  2017年   3367篇
  2016年   2932篇
  2015年   3853篇
  2014年   4885篇
  2013年   6249篇
  2012年   6553篇
  2011年   7176篇
  2010年   6243篇
  2009年   6163篇
  2008年   6156篇
  2007年   5745篇
  2006年   6037篇
  2005年   5413篇
  2004年   3693篇
  2003年   3197篇
  2002年   2851篇
  2001年   2756篇
  2000年   2872篇
  1999年   3381篇
  1998年   2910篇
  1997年   2546篇
  1996年   2286篇
  1995年   1921篇
  1994年   1551篇
  1993年   1219篇
  1992年   964篇
  1991年   738篇
  1990年   600篇
  1989年   500篇
  1988年   390篇
  1987年   294篇
  1986年   206篇
  1985年   176篇
  1984年   108篇
  1983年   81篇
  1982年   87篇
  1981年   57篇
  1980年   46篇
  1979年   32篇
  1978年   25篇
  1977年   25篇
  1976年   40篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
Chen  Yaqi  Wu  Xiaoren  Liu  Qing  He  Maoshuai  Bai  Hongcun 《Catalysis Letters》2022,152(9):2738-2744

This work proposed a new path to synthesize Ni-phyllosilicate through the reaction of nickel hydroxide and silica sol on the surface of Ni-foam to form the monolithic Ni-phyllosilicate/Ni-foam catalyst. Ni-phyllosilicate could reprint the morphology of nickel hydroxid and firmly anchor on the framework of Ni-foam, which obtained fine Ni particles of 2.8 nm after reduction in H2 at 650 °C, resulting in high catalytic activity for CO2 methanation. In addition, the Ni-phyllosilicate/Ni-foam catalyst showed high long-term stability in a 100 h-lifetime test owing to the combined effects of surface confinement of Ni-phyllosilicate, firm anchoring between Ni-phyllosilicate and Ni-foam, as well as the high heat transfer property of Ni-foam.

Graphical Abstract
  相似文献   
12.
Liu  Song  Cui  Yuan-Zhen  Zou  Nian-Jun  Zhu  Wen-Hao  Zhang  Dong  Wu  Wei-Guo 《计算机科学技术学报》2019,34(2):456-475
Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front...  相似文献   
13.
Electromagnetic signal emitted by satellite communication (satcom) transmitters are used to identify specific individual uplink satcom terminals sharing the common transponder in real environment, which is known as specific emitter identification (SEI) that allows for early indications and warning (I&W) of the targets carrying satcom furnishment and furthermore the real time electromagnetic situation awareness in military operations. In this paper, the authors are the first to propose the identification of specific transmitters of satcom by using probabilistic neural networks (PNN) to reach the goal of target recognition. We have been devoted to the examination by exploring the feasibility of utilizing the Hilbert transform to signal preprocessing, applying the discrete wavelet transform to feature extraction, and employing the PNN to perform the classification of stationary signals. There are a total of 1000 sampling time series with binary phase shift keying (BPSK) modulation originated by five types of satcom transmitters in the test. The established PNNs classifier implements the data testing and finally yields satisfactory accuracy at 8 dB(±1 dB) carrier to noise ratio, which indicates the feasibility of our method, and even the keen insight of its application in military.  相似文献   
14.
International Journal of Computer Vision - Expressive representations for characterizing face appearances are essential for accurate face detection. Due to different poses, scales, illumination,...  相似文献   
15.
International Journal of Information Security - Data integrity is a critical security issue in cloud storage. The data integrity checking schemes by a third-party auditor (TPA) have attracted a lot...  相似文献   
16.
In order to predict the wearing of stellite alloys,the related methods of rare metals data processing were discussed. The method of opposite degree(OD) algorithm was put forward to predict the wearing of stellite alloys.OD algorithm is based on prior numerical data, posterior numerical data and the opposite degree between numerical forecast data. To compare the performance of predicted results based on different algorithms, the back propagation(BP) and radial basis function(RBF) neural network methods were introduced. Predicted results show that the relative error of OD algorithm is smaller than those of BP and RBF neural network methods. OD algorithm is an effective method to predict the wearing of stellite alloys and it can be applied in practice.  相似文献   
17.
18.
19.
20.
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