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   592784篇
  免费   8392篇
  国内免费   1133篇
电工技术   10832篇
综合类   714篇
化学工业   95215篇
金属工艺   23928篇
机械仪表   19098篇
建筑科学   13541篇
矿业工程   4415篇
能源动力   15250篇
轻工业   49229篇
水利工程   7177篇
石油天然气   15107篇
武器工业   47篇
无线电   62244篇
一般工业技术   119919篇
冶金工业   101473篇
原子能技术   14856篇
自动化技术   49264篇
  2021年   6262篇
  2020年   4569篇
  2019年   5837篇
  2018年   9969篇
  2017年   10194篇
  2016年   10604篇
  2015年   6663篇
  2014年   11117篇
  2013年   27568篇
  2012年   16998篇
  2011年   22596篇
  2010年   18057篇
  2009年   19920篇
  2008年   20164篇
  2007年   19680篇
  2006年   17026篇
  2005年   15528篇
  2004年   14851篇
  2003年   14495篇
  2002年   13976篇
  2001年   13489篇
  2000年   12787篇
  1999年   12447篇
  1998年   29449篇
  1997年   21204篇
  1996年   16460篇
  1995年   12543篇
  1994年   11287篇
  1993年   11095篇
  1992年   8503篇
  1991年   8330篇
  1990年   8172篇
  1989年   7926篇
  1988年   7661篇
  1987年   6890篇
  1986年   6680篇
  1985年   7552篇
  1984年   6804篇
  1983年   6530篇
  1982年   5882篇
  1981年   6013篇
  1980年   5745篇
  1979年   5814篇
  1978年   5747篇
  1977年   6321篇
  1976年   7894篇
  1975年   5180篇
  1974年   4935篇
  1973年   5027篇
  1972年   4310篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
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   
102.
Journal of Communications Technology and Electronics - Abstract—The article considers the two-dimensional diffraction problem of a TM-type plane electromagnetic wave on a cylindrical silver...  相似文献   
103.
Strength of Materials - The statistical analysis performed on the defectiveness of rails in the Kiev subway railway shows that the main cause of the occurrence of most defects is the contact...  相似文献   
104.
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   
105.
Measurement Techniques - A method is proposed for transferring the unit of mean power of laser radiation by means of measuring high-intensity power (kilowatts), with the possibility of constant...  相似文献   
106.
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   
107.
In this paper, a new inverse identification method of constitutive parameters is developed from full kinematic and thermal field measurements. It consists in reconstructing the heat source field from two different approaches by using the heat diffusion equation. The first one requires the temperature field measurement and the value of the thermophysical parameters. The second one is based on the kinematic field measurement and the choice of a thermo-hyperelastic model that contains the parameters to be identified. The identification is carried out at the local scale, ie, at any point of the heat source field, without using the boundary conditions. In the present work, the method is applied to the challenging case of hyperelasticity from a heterogeneous test. Due to large deformations undergone by the rubber specimen tested, a motion compensation technique is developed to plot the kinematic and the thermal fields at the same points before reconstructing the heterogeneous heat source field. In the present case, the constitutive parameter of the Neo-Hookean model has been identified, and its distribution has been characterized with respect to the strain state at the surface of a cross-shaped specimen.  相似文献   
108.
109.
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   
110.
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