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   572493篇
  免费   6467篇
  国内免费   1020篇
电工技术   10577篇
综合类   473篇
化学工业   91338篇
金属工艺   23432篇
机械仪表   18632篇
建筑科学   12831篇
矿业工程   4321篇
能源动力   14627篇
轻工业   46218篇
水利工程   6997篇
石油天然气   14985篇
武器工业   41篇
无线电   60802篇
一般工业技术   117157篇
冶金工业   96343篇
原子能技术   14711篇
自动化技术   46495篇
  2021年   5627篇
  2020年   4114篇
  2019年   5378篇
  2018年   9362篇
  2017年   9555篇
  2016年   10001篇
  2015年   6174篇
  2014年   10443篇
  2013年   26467篇
  2012年   16099篇
  2011年   21447篇
  2010年   17252篇
  2009年   19145篇
  2008年   19369篇
  2007年   19086篇
  2006年   16508篇
  2005年   14963篇
  2004年   14196篇
  2003年   13850篇
  2002年   13377篇
  2001年   12940篇
  2000年   12425篇
  1999年   12107篇
  1998年   27739篇
  1997年   20137篇
  1996年   15701篇
  1995年   12092篇
  1994年   10932篇
  1993年   10665篇
  1992年   8390篇
  1991年   8128篇
  1990年   8032篇
  1989年   7817篇
  1988年   7521篇
  1987年   6779篇
  1986年   6576篇
  1985年   7442篇
  1984年   6742篇
  1983年   6484篇
  1982年   5808篇
  1981年   5930篇
  1980年   5657篇
  1979年   5756篇
  1978年   5678篇
  1977年   6192篇
  1976年   7706篇
  1975年   5131篇
  1974年   4923篇
  1973年   4990篇
  1972年   4286篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
A new commercially available diode model is described. This unified model is capable of simulating the widest range of diode technologies of any presently available. The emphasis of this paper is on describing the model's extensive features and flexibility in the different domains of operation and is of particular interest in power applications  相似文献   
62.
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   
63.
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   
64.
65.
Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 95–112, March–April, 1994.  相似文献   
66.
67.
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   
68.
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   
69.
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   
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