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   405164篇
  免费   5561篇
  国内免费   1355篇
电工技术   7590篇
综合类   316篇
化学工业   59902篇
金属工艺   16470篇
机械仪表   13586篇
建筑科学   8504篇
矿业工程   2167篇
能源动力   11647篇
轻工业   28935篇
水利工程   4290篇
石油天然气   7925篇
武器工业   17篇
无线电   49380篇
一般工业技术   83393篇
冶金工业   75049篇
原子能技术   9202篇
自动化技术   33707篇
  2021年   3987篇
  2020年   3038篇
  2019年   3911篇
  2018年   6614篇
  2017年   6591篇
  2016年   7063篇
  2015年   4431篇
  2014年   7285篇
  2013年   20260篇
  2012年   11614篇
  2011年   15502篇
  2010年   12307篇
  2009年   13886篇
  2008年   14195篇
  2007年   13943篇
  2006年   12528篇
  2005年   11210篇
  2004年   10597篇
  2003年   10483篇
  2002年   9886篇
  2001年   9774篇
  2000年   9165篇
  1999年   9550篇
  1998年   24352篇
  1997年   16727篇
  1996年   12821篇
  1995年   9543篇
  1994年   8376篇
  1993年   8392篇
  1992年   6069篇
  1991年   5704篇
  1990年   5688篇
  1989年   5329篇
  1988年   5048篇
  1987年   4425篇
  1986年   4308篇
  1985年   4824篇
  1984年   4426篇
  1983年   4000篇
  1982年   3660篇
  1981年   3736篇
  1980年   3429篇
  1979年   3328篇
  1978年   3334篇
  1977年   3726篇
  1976年   4827篇
  1975年   2840篇
  1974年   2639篇
  1973年   2706篇
  1972年   2266篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Chemical and Petroleum Engineering - The hydrodynamics of oxidation towers used for bitumen production were studied using a model tower having transparent walls. Experiments were carried out in two...  相似文献   
32.
Journal of Engineering Physics and Thermophysics - A numerical investigation has been made into the interaction of slender (5–20 calibers) steel cylinder strikers with orthotropic compost...  相似文献   
33.
Deshmukh  P.  Sar  S. K.  Smječanin  N.  Nuhanović  M.  Lalwani  R. 《Radiochemistry》2022,64(4):532-542
Radiochemistry - Magnetically modified waste bark of the Aegle marmelos tree was prepared by using green synthesis method and was used in a batch system for U(VI) removal from aqueous solution. The...  相似文献   
34.
Kamar  M. S.  Shalan  A. S.  Youssef  W. M.  Hussein  A. E. M.  Khawassek  Y. M.  Taha  M. H. 《Radiochemistry》2022,64(2):244-256
Radiochemistry - Ferrugination, sericitization, desulfitization, chloritization, and kaolinitization of hydrothermal origin are the main wall rock alterations occurring within the NNW shear zones...  相似文献   
35.

Modern metrics for evaluating agreement coefficients between the experimental results and expert opinion are compared, and the possibility of using these metrics in experimental research in automatic text processing by machine learning methods is assessed. The choice of Cohen’s kappa coefficient as a measure of expert opinion agreement in the NLP and Text Mining problems is justified. An example of using Cohen’s kappa coefficient for evaluating the level of agreement between the opinion of an expert and the results of ML classification and the measure of agreement of expert opinions in the alignment of sentences of the Kazakh-Russian parallel corpus is given. Based on this analysis, it is proved that Cohen’s kappa coefficient is one of the best statistical methods for determining the level of agreement in experimental studies due to its ease of use, computing simplicity, and high accuracy of the results.

  相似文献   
36.
Wireless Personal Communications - Multiple inputs multiple outputs (MIMO) is a reliable technique which can manage the increased wireless data traffic in the future generation of wireless...  相似文献   
37.
Multimedia Tools and Applications - Discovering the relevant web services for specific applications in the dynamically changing business world becomes very critical. Researchers have used many...  相似文献   
38.
Mobile Networks and Applications - 5G/6G communication are first generation high speed wireless communication network which integrates the aerial data, terrestrial data and maritime data via...  相似文献   
39.
Theoretical Foundations of Chemical Engineering - The effect of the electrolyte composition, mass-transfer conditions, pore diameter, interpore distance, and electric parameters on the formation of...  相似文献   
40.
The influence of the microstructure on the corrosion rate of three monolithic SiC samples in FLiNaK salt at 900 °C for 250 h was studied. The SiC samples, labeled as SiC-1, SiC-2, and SiC-3, had corrosion rates of 0.137, 0.020, and 0.043 mg/cm2h, respectively. Compared with grain size and the presence of special grain boundaries (i.e., Σ3), the content of high-angle grain boundaries (HAGBs) appeared to have the strongest influence on the corrosion rate of SiC in FLiNaK salt, since the corrosion rate increased six times as the concentration of high-angle grain boundaries increased from 19 to 32% for SiC-2 and SiC-1, respectively. These results stress the importance of controlling the content of HAGBs during the production process of SiC.  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