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   566842篇
  免费   6232篇
  国内免费   1005篇
电工技术   10510篇
综合类   466篇
化学工业   90071篇
金属工艺   23336篇
机械仪表   18499篇
建筑科学   12530篇
矿业工程   4312篇
能源动力   14438篇
轻工业   45765篇
水利工程   6941篇
石油天然气   14961篇
武器工业   39篇
无线电   60289篇
一般工业技术   116239篇
冶金工业   95567篇
原子能技术   14682篇
自动化技术   45434篇
  2021年   5490篇
  2019年   5269篇
  2018年   9205篇
  2017年   9415篇
  2016年   9837篇
  2015年   6034篇
  2014年   10248篇
  2013年   26108篇
  2012年   15780篇
  2011年   21098篇
  2010年   16973篇
  2009年   18820篇
  2008年   19073篇
  2007年   18767篇
  2006年   16285篇
  2005年   14744篇
  2004年   14009篇
  2003年   13691篇
  2002年   13246篇
  2001年   12851篇
  2000年   12330篇
  1999年   12013篇
  1998年   27649篇
  1997年   20041篇
  1996年   15628篇
  1995年   12006篇
  1994年   10858篇
  1993年   10612篇
  1992年   8332篇
  1991年   8103篇
  1990年   7990篇
  1989年   7763篇
  1988年   7479篇
  1987年   6748篇
  1986年   6533篇
  1985年   7390篇
  1984年   6700篇
  1983年   6437篇
  1982年   5776篇
  1981年   5896篇
  1980年   5631篇
  1979年   5733篇
  1978年   5663篇
  1977年   6178篇
  1976年   7686篇
  1975年   5108篇
  1974年   4903篇
  1973年   4980篇
  1972年   4279篇
  1971年   4039篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
The capacitive idling converters derived from the Cuk, SEPIC, Zeta, and flyback topologies allow soft commutation of power switches without the need for additional circuitry, making it possible to increase the switching frequency while maintaining high efficiency  相似文献   
62.
Pipelining and bypassing in a VLIW processor   总被引:1,自引:0,他引:1  
This short note describes issues involved in the bypassing mechanism for a very long instruction word (VLIW) processor and its relation to the pipeline structure of the processor. The authors first describe the pipeline structure of their processor and analyze its performance and compare it to typical RISC-style pipeline structures given the context of a processor with multiple functional units. Next they study the performance effects of various bypassing schemes in terms of their effectiveness in resolving pipeline data hazards and their effect on the processor cycle time  相似文献   
63.
64.
Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 95–112, March–April, 1994.  相似文献   
65.
66.
The process of combustion of homogeneous and heterogeneous nongasifying and slightly gasifying systems over the range of a number of parameters characterizing the reactive composition and the conditions for the arrangement of the combustion process is studied by using thermocouple and optical methods. The regions of the implementation of different combustion regimes, namely, steady, pulsating, multiple-point, and spin, are determined experimentally.Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 4, pp. 407–411, October, 1993.  相似文献   
67.
An extended logistic model with a varying asymptotic upper bound for long-range peak demand forecasting is described. The model has been applied to a typical fast growing system, the Saudi Consolidated Electric Company. The forecasts are compared with actual demands and with those obtained from classical forecasting methods. The model gave relatively accurate peak demand forecasts compared with other classical methods. The model with a single load observation is capable of producing several peak demand forecasts corresponding to different levels of maximum temperature and various levels of social activity. The forecasts produced by the model were also stable irrespective of the length of the ex-post simulation period  相似文献   
68.
An experimental and theoretical analysis of the nonlinear coupling mechanism between the two solitary pulses circulating in a two-color femtosecond laser is presented. Two operation regimes; synchronized; and nonsynchronized; and a hysteresis of the transition between the two regimes are clearly observed; while independent modelocking and tunability of the output pulse trains is found in both regimes. Pulses in the range from 15 to 100 fs are synchronized with a timing jitter below 2 fs. The combined effects of cross-phase modulation and negative group velocity dispersion are shown to be responsible for the strong pulse correlation in the synchronized regime. Our experimental observations are in agreement with numerical simulations, thus confirming the theoretical model  相似文献   
69.
70.
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