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   609928篇
  免费   6758篇
  国内免费   1639篇
电工技术   11363篇
综合类   504篇
化学工业   96267篇
金属工艺   24973篇
机械仪表   19732篇
建筑科学   13649篇
矿业工程   4553篇
能源动力   15632篇
轻工业   49971篇
水利工程   7428篇
石油天然气   15905篇
武器工业   77篇
无线电   64516篇
一般工业技术   125104篇
冶金工业   103476篇
原子能技术   16059篇
自动化技术   49116篇
  2021年   5887篇
  2020年   4344篇
  2019年   5580篇
  2018年   9784篇
  2017年   10031篇
  2016年   10507篇
  2015年   6500篇
  2014年   10961篇
  2013年   28083篇
  2012年   16908篇
  2011年   22549篇
  2010年   18190篇
  2009年   20244篇
  2008年   20451篇
  2007年   20158篇
  2006年   17504篇
  2005年   15797篇
  2004年   15104篇
  2003年   14737篇
  2002年   14280篇
  2001年   13874篇
  2000年   13311篇
  1999年   12998篇
  1998年   30193篇
  1997年   21832篇
  1996年   16944篇
  1995年   13050篇
  1994年   11782篇
  1993年   11527篇
  1992年   8964篇
  1991年   8771篇
  1990年   8658篇
  1989年   8401篇
  1988年   8056篇
  1987年   7306篇
  1986年   7076篇
  1985年   7956篇
  1984年   7192篇
  1983年   6894篇
  1982年   6224篇
  1981年   6320篇
  1980年   6058篇
  1979年   6127篇
  1978年   6027篇
  1977年   6672篇
  1976年   8319篇
  1975年   5466篇
  1974年   5259篇
  1973年   5292篇
  1972年   4585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