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   640215篇
  免费   9269篇
  国内免费   2022篇
电工技术   11763篇
综合类   687篇
化学工业   97210篇
金属工艺   25596篇
机械仪表   20009篇
建筑科学   14553篇
矿业工程   3686篇
能源动力   17029篇
轻工业   51846篇
水利工程   6784篇
石油天然气   12958篇
武器工业   38篇
无线电   73357篇
一般工业技术   128231篇
冶金工业   120129篇
原子能技术   14314篇
自动化技术   53316篇
  2021年   5779篇
  2020年   4462篇
  2019年   5471篇
  2018年   9577篇
  2017年   9389篇
  2016年   10199篇
  2015年   6656篇
  2014年   10747篇
  2013年   30196篇
  2012年   17112篇
  2011年   22904篇
  2010年   18403篇
  2009年   20823篇
  2008年   21409篇
  2007年   21017篇
  2006年   18626篇
  2005年   16874篇
  2004年   15785篇
  2003年   15615篇
  2002年   15017篇
  2001年   14772篇
  2000年   13930篇
  1999年   14447篇
  1998年   36959篇
  1997年   26100篇
  1996年   20078篇
  1995年   14994篇
  1994年   13315篇
  1993年   13188篇
  1992年   9609篇
  1991年   9166篇
  1990年   9065篇
  1989年   8796篇
  1988年   8521篇
  1987年   7301篇
  1986年   7268篇
  1985年   8278篇
  1984年   7702篇
  1983年   7019篇
  1982年   6541篇
  1981年   6688篇
  1980年   6297篇
  1979年   6121篇
  1978年   6223篇
  1977年   7170篇
  1976年   9378篇
  1975年   5456篇
  1974年   5124篇
  1973年   5278篇
  1972年   4452篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Fefelov  S. A.  Kazakova  L. P.  Bogoslovskiy  N. A.  Bylev  A. B.  Yakubov  A. O. 《Semiconductors》2020,54(4):450-453
Semiconductors - The current–voltage characteristics measured on Ge2Sb2Te5 thin films in the current mode are studied. The effect of multilevel recording is established when applying...  相似文献   
92.
Hussien  O. S.  Elamy  M. I. 《Strength of Materials》2020,52(3):470-479
Strength of Materials - The use of a damping system is one of the seismic protection systems that improve the seismic response of structures. The proposed methodology estimates the location (which...  相似文献   
93.
Powder Metallurgy and Metal Ceramics - The infiltration of aluminum melts into porous metal skeletons produced by powder metallurgy methods, including 3D printing, under a pressure gradient was...  相似文献   
94.
As a solid state joining process, ultrasonic spot welding has been proven to be a promising technique for joining copper alloys. However, challenges still remain in employing ultrasonic spot welding to join copper alloys. This article comprehensively reviews the current state of ultrasonic spot welding of copper alloys with a number of critical issues including materials flow, plastic deformation, temperature distribution, vibration, relative motion, vertical displacement, interface friction coefficient, online monitoring technique, coupled with the macrostructure and microstructure, the mechanical properties and electrical conductivity. In addition, the future trends in this field are provided.  相似文献   
95.
Wireless Personal Communications - In the fusion experiment, sensitive radio frequency signal diagnostic instruments need to be protected against high power stray radiation coming from the Electron...  相似文献   
96.
Sustainable and efficient food supply chain has become an essential component of one’s life. The model proposed in this paper is deeply linked to people's quality of life as a result of which there is a large incentive to fulfil customer demands through it. This proposed model can enhance food quality by making the best possible food quality accessible to customers, construct a sustainable logistics system considering its environmental impact and ensure the customer demand to be fulfilled as fast as possible. In this paper, an extended model is examined that builds a unified planning problem for efficient food logistics operations where four important objectives are viewed: minimising the total expense of the system, maximising the average food quality along with the minimisation of the amount of CO2 emissions in transportation along with production and total weighted delivery lead time minimisation. A four objective mixed integer linear programming model for intelligent food logistics system is developed in the paper. The optimisation of the formulated mathematical model is proposed using a modified multi-objective particle swarm optimisation algorithm with multiple social structures: MO-GLNPSO (Multi-Objective Global Local Near-Neighbour Particle Swarm Optimisation). Computational results of a case study on a given dataset as well as on multiple small, medium and large-scale datasets followed by sensitivity analysis show the potency and effectiveness of the introduced method. Lastly, there has been a scope for future study displayed which would lead to the further progress of these types of models.  相似文献   
97.
98.
Theoretical Foundations of Chemical Engineering - A set of measures to establish the technology for manufacturing highly active sources of γ radiation with an active part from...  相似文献   
99.
Metallurgical and Materials Transactions B - The quality requirements of aluminum products are steadily increasing, and the presence of non-metallic inclusions have a large impact on the quality of...  相似文献   
100.
Puzanov  A. S.  Obolenskiy  S. V.  Kozlov  V. A. 《Semiconductors》2020,54(8):946-950
Semiconductors - On the basis of the Monte Carlo algorithm, a method for calculating the energy spectrum of hot nonequilibrium electrons and holes in the track of a primary recoil atom after being...  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