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   756039篇
  免费   8091篇
  国内免费   1383篇
电工技术   13738篇
综合类   760篇
化学工业   118448篇
金属工艺   32367篇
机械仪表   24795篇
建筑科学   17214篇
矿业工程   5321篇
能源动力   18125篇
轻工业   63011篇
水利工程   8973篇
石油天然气   17379篇
武器工业   65篇
无线电   79138篇
一般工业技术   152323篇
冶金工业   130223篇
原子能技术   17791篇
自动化技术   65842篇
  2021年   6507篇
  2019年   6256篇
  2018年   14748篇
  2017年   15016篇
  2016年   13906篇
  2015年   7395篇
  2014年   12209篇
  2013年   32449篇
  2012年   20395篇
  2011年   29928篇
  2010年   24614篇
  2009年   26337篇
  2008年   26970篇
  2007年   27936篇
  2006年   20520篇
  2005年   20097篇
  2004年   18705篇
  2003年   18253篇
  2002年   17181篇
  2001年   16338篇
  2000年   15806篇
  1999年   15511篇
  1998年   36402篇
  1997年   26188篇
  1996年   20395篇
  1995年   15736篇
  1994年   14159篇
  1993年   13854篇
  1992年   10829篇
  1991年   10332篇
  1990年   10350篇
  1989年   10110篇
  1988年   9738篇
  1987年   8688篇
  1986年   8524篇
  1985年   9712篇
  1984年   8940篇
  1983年   8440篇
  1982年   7689篇
  1981年   7813篇
  1980年   7540篇
  1979年   7523篇
  1978年   7445篇
  1977年   8277篇
  1976年   10478篇
  1975年   6721篇
  1974年   6411篇
  1973年   6530篇
  1972年   5587篇
  1971年   5198篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A method is considered to solve a conditional optimization problem with a linear-fractional objective function over permutations. The performance of sub algorithms to solve this problem is evaluated. The practical efficiency of the algorithm is analyzed by conducting numerical experiments. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 133–146, July–August 2007.  相似文献   
992.
Cloning of observables, unlike standard cloning of states, aims at copying the information encoded in the statistics of a class of observables rather then on quantum states themselves. In such a process the emphasis is on the quantum operation (evolution plus measurement) necessary to retrieve the original information. We analyze, for qubit systems, the cloning of a class generated by two noncommuting observables, elucidating the relationship between such a process and joint measurements. This helps in establishing an optimality criterion for cloning of observables. We see that, even if the cloning machine is designed to act on the whole class generated by two noncommuting observables, the same optimal performances of a joint measurement can be attained. Finally, the connection with state dependent cloning is enlightened.  相似文献   
993.
The problem of synthesizing trajectories, planning and implementing the motion of a mobile robot is investigated. The statement of the problem is motivated by the need for designing an optimal control of robots with two wheels controlled independently. Mobile robots with this kinematic scheme are called robots with “differential drive.”  相似文献   
994.
995.
996.
This article is devoted to work done in 2002–2006 as part of the unified project Reabilitatsiya to rehabilitate radiation hazardous objects and sections of the radioactively contaminated territory of the Russian Science Center Kurchatov Institute. The main objects of the rehabilitation work were old storage sites built for radioactive wastes on the territory of the Institute when military and civilian nuclear technologies were under development. The structural features of the storage sites, including the volumes and characteristics of the wastes stored, are presented. The salient aspects of the disposal sites, taken into account during the rehabilitation work, are discussed. The organization of the rehabilitation operations and the sequence in which they are performed, the special features of the technical design solutions used, the technological methods, and ways for conducting the work are described. __________ Translated from Atomnaya énergiya, Vol. 102, No. 5, pp. 300–306, May, 2007.  相似文献   
997.
The Bahrain International Circuit (BIC) is considered as one of the best international racing car track in terms of technical aspects and architectural quality. Two Formula 1 races have been hosted in the Kingdom of Bahrain, in 2004 and 2005, at BIC. The BIC had recently won the award of the best international racing car circuit.  相似文献   
998.
The effect of tempering temperature on the structure, wear resistance, and corrosive properties of steel 08Kh14AN4MDB is studied. The results of mechanical and corrosion tests are used for constructing an optimization matrix for determining the optimum tempering temperature. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 29–32, February, 2007.  相似文献   
999.
We present the results of electric discharge treatment of zeolites for purifying the waste water from the manufacture of polymers. By application of the thermostimulated relaxation method, it has been revealed that in the zeolites, superficial and volumetric charges accumulate. It is shown that the electric discharge effects considerably enhance the efficiency of the adsorptive purification of waste water.  相似文献   
1000.
A new torque estimator for switched reluctance motor (SRM) drives based on 2-D rotary regression analysis is presented in this paper. The proposed torque estimator is composed of a bicubic regressive polynomial as a function of rotor position and input current. The regressive coefficients can be computed offline or online from the torque characteristics acquired either experimentally or from numerical computation. Furthermore, a torque estimation method by taking mutual coupling into consideration is proposed. It can be seen that the estimated and experimentally obtained self-coupling and mutual-coupling torque characteristics are in good agreement with each other. In addition, the dynamic torque waveforms with and without the mutual coupling, estimated by the proposed estimator, are found to be virtually the same as those obtained from the bicubic spline interpolation for SRM drives with single-pulse voltage, hysteresis current chopping, as well as with voltage pulse width modulation control. The success of all the case studies being reported is a good validation of the usefulness and accuracy of the proposed real-time torque estimator that, as described in this paper, can be used to quickly estimate the instantaneous output torque of SRM drives.  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