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   654295篇
  免费   6990篇
  国内免费   1115篇
电工技术   11753篇
综合类   552篇
化学工业   102966篇
金属工艺   27746篇
机械仪表   20910篇
建筑科学   14482篇
矿业工程   5158篇
能源动力   16047篇
轻工业   50901篇
水利工程   8341篇
石油天然气   18426篇
武器工业   42篇
无线电   68277篇
一般工业技术   135148篇
冶金工业   112193篇
原子能技术   17329篇
自动化技术   52129篇
  2021年   6048篇
  2019年   5822篇
  2018年   10243篇
  2017年   10422篇
  2016年   10938篇
  2015年   6732篇
  2014年   11482篇
  2013年   29339篇
  2012年   17658篇
  2011年   23653篇
  2010年   19004篇
  2009年   21212篇
  2008年   21532篇
  2007年   21184篇
  2006年   18454篇
  2005年   16776篇
  2004年   15953篇
  2003年   15567篇
  2002年   15128篇
  2001年   14737篇
  2000年   14135篇
  1999年   13862篇
  1998年   32331篇
  1997年   23352篇
  1996年   18118篇
  1995年   13874篇
  1994年   12514篇
  1993年   12333篇
  1992年   9580篇
  1991年   9363篇
  1990年   9262篇
  1989年   8934篇
  1988年   8626篇
  1987年   7880篇
  1986年   7651篇
  1985年   8555篇
  1984年   7799篇
  1983年   7533篇
  1982年   6800篇
  1981年   6988篇
  1980年   6715篇
  1979年   6912篇
  1978年   6904篇
  1977年   7518篇
  1976年   9449篇
  1975年   6288篇
  1974年   6093篇
  1973年   6202篇
  1972年   5396篇
  1971年   4975篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
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   
72.
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   
73.
74.
Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 95–112, March–April, 1994.  相似文献   
75.
76.
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   
77.
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   
78.
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   
79.
80.
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