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   19585篇
  免费   260篇
  国内免费   85篇
电工技术   707篇
综合类   89篇
化学工业   2866篇
金属工艺   1259篇
机械仪表   1598篇
建筑科学   335篇
矿业工程   307篇
能源动力   121篇
轻工业   398篇
水利工程   378篇
石油天然气   856篇
武器工业   11篇
无线电   2022篇
一般工业技术   4991篇
冶金工业   2006篇
原子能技术   414篇
自动化技术   1572篇
  2023年   49篇
  2022年   298篇
  2021年   456篇
  2020年   366篇
  2019年   518篇
  2018年   1080篇
  2017年   1128篇
  2016年   1323篇
  2015年   742篇
  2014年   1089篇
  2013年   1417篇
  2012年   1282篇
  2011年   1160篇
  2010年   1155篇
  2009年   1338篇
  2008年   1227篇
  2007年   1173篇
  2006年   931篇
  2005年   544篇
  2004年   305篇
  2003年   138篇
  2002年   141篇
  2001年   135篇
  2000年   451篇
  1999年   339篇
  1998年   329篇
  1997年   339篇
  1996年   46篇
  1995年   15篇
  1994年   15篇
  1993年   12篇
  1992年   14篇
  1991年   11篇
  1990年   21篇
  1985年   18篇
  1984年   15篇
  1983年   12篇
  1980年   14篇
  1979年   15篇
  1978年   21篇
  1976年   19篇
  1974年   12篇
  1973年   9篇
  1971年   9篇
  1970年   11篇
  1969年   23篇
  1968年   15篇
  1967年   10篇
  1960年   10篇
  1959年   10篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
A theoretical method for determining the percolation limit and effective conductivity of composites based on polydisperse mixtures of insulator and conductor powders is proposed. The effect of the particle size ratio between the insulator and conductor on the percolation limit and effective conductivity is studied. Numerical simulation of the microstructure, effective properties, and percolation limit in composites is discussed. __________ Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 1–2(453), pp. 31–40, 2007.  相似文献   
42.
A new approach to synthesize algorithms for selective control of the observables in quantum mechanical systems in the presence of additional constraints during the whole period of control is proposed. Analytic results of achieving the goal of control under some additional assumptions were obtained. It was demonstrated that the error in achieving the goal of control is proportionate to the error in prescribing the initial state of system and the error in realizing the control action. Numerical results for the problem of selective control for energy of hydrogen molecules (H2) with different isotopes are represented. The proposed algorithms are easy to design.  相似文献   
43.
The possibility of determining the total α activity A(239,240Pu) of 239Pu + 240Pu according to the γ radiation of 103Ru and 106Ru is examined. The statistical properties of the experimental ratios of the activities ρ = A(106Ru)/A(103Ru) are investigated. The distribution of the experimental ratios is similar to the theoretical ratios for fuel and close to a Gaussian distribution with average value 〈p〉 = 0.22 and standard deviation Δ ∼ 0.06. This ratio is used to obtain a relation for estimating A(239,240Pu) from the γ activity A(103Ru). A theoretical analysis is made of the experimental data for the southern raions of Gomel oblast. It is shown that given a good statistical sample of measurements of the γ activity of 103Ru it is possible to estimate the average value of the γ activity A(239,240Pu) and with probability 0.95 the interval of the possible values of this activity. __________ Translated from Atomnaya énergiya, Vol. 103, No. 4, pp. 255–259, October, 2007.  相似文献   
44.
The results of investigations performed by specialists at Research and Design Institute of Electrical Technology together with other enterprises, institutes, and organizations concerning the formulation of a strategy for the development of nuclear power in Russia in the first half of the 21st century are presented. The individual stages of the work, key assumptions, ideas, and recommendations, on which the strategy is based, the initiatives which the President of the Russian Federation advanced at the millennium summit held at the United Nations, and the international INPRO project initiated by Russia are examined. It is concluded that innovative development and a transition to building as quickly as possible nuclear power objects that meet the requirements and demands of the new century are necessary. __________ Translated from Atomnaya énergiya,Vol. 103, No. 1, pp. 5–15, July, 2007.  相似文献   
45.
The results of development work on an innovative low-capacity nuclear power plant (LCNPP) Uniterm together with substantiation of the need for a technical design of a reactor system and the basic design of the power plant are presented. The results of the work are used to determine the power range of the power generating unit where the main consumer qualities are guaranteed to be attained. Economic assessments of the development and operation of a two-block LCNPP under conditions in Russia are presented. __________ Translated from Atomnaya énergiya,Vol. 103, No. 1, pp. 44–48, July, 2007.  相似文献   
46.
47.
48.
49.
50.
An approach to the reconstruction problem of undistorted images of objects observed through randomly inhomogeneous media is considered. The approach is based on the solution to the integral equation of the first kind (convolution equation) with an unknown kernel and inaccurately defined right-hand side. It is demonstrated that the procedure for the construction of an inverse operator needed for the solution is determined by the minimization of the nonlinear regularizing multiextremum functional, which takes into account the a priori data regarding the positive intensity distribution in the image of an object. The analysis of the structure of the multiextremum functional is presented. The estimates of the reconstructed images that correspond to the global and local extrema are studied. The results of a numerical experiment on the reconstruction of the optical image of an object observed through the turbulent atmosphere are presented.  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