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   702426篇
  免费   17883篇
  国内免费   7066篇
电工技术   18598篇
技术理论   9篇
综合类   9169篇
化学工业   112352篇
金属工艺   30983篇
机械仪表   26815篇
建筑科学   22013篇
矿业工程   7834篇
能源动力   17879篇
轻工业   54976篇
水利工程   9622篇
石油天然气   22233篇
武器工业   1084篇
无线电   75269篇
一般工业技术   134889篇
冶金工业   102829篇
原子能技术   17225篇
自动化技术   63596篇
  2022年   8040篇
  2021年   11206篇
  2020年   8298篇
  2019年   8785篇
  2018年   13269篇
  2017年   13876篇
  2016年   13797篇
  2015年   11136篇
  2014年   16637篇
  2013年   33750篇
  2012年   24222篇
  2011年   30073篇
  2010年   24624篇
  2009年   26250篇
  2008年   26429篇
  2007年   25628篇
  2006年   22876篇
  2005年   20363篇
  2004年   18151篇
  2003年   17817篇
  2002年   17455篇
  2001年   16651篇
  2000年   15506篇
  1999年   14942篇
  1998年   29899篇
  1997年   21863篇
  1996年   17277篇
  1995年   13498篇
  1994年   12055篇
  1993年   11551篇
  1992年   9194篇
  1991年   8805篇
  1990年   8609篇
  1989年   8333篇
  1988年   7967篇
  1987年   7181篇
  1986年   6889篇
  1985年   7705篇
  1984年   6995篇
  1983年   6698篇
  1982年   6067篇
  1981年   6188篇
  1980年   5902篇
  1979年   6045篇
  1978年   5993篇
  1977年   6478篇
  1976年   8015篇
  1975年   5426篇
  1974年   5202篇
  1973年   5291篇
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
81.
The technological process of cold forging applied for the first time in the production of the casing of the internal joint with races is described. The process operations of cold forging and the annealing and carburizing regimes for this part me described.  相似文献   
82.
Many current implementations of protocols such as the Transmission Control Protocol/Internet Protocol (TCP/IP) are inefficient because data are often accessed more frequently than necessary. Three techniques that reduce the need for memory bandwidth are proposed. The techniques are copy-on-write, page remapping, and single-copy. Afterburner, a network-independent card that provides the services that are necessary for a single-copy protocol stack, is described. The card has 1 MByte of local buffers and provides a simple interface to a variety of network link adapters, including HIPPI and asynchronous transfer mode (ATM). Afterburner can support transfers to and from the link adapter card at rates up to 1 Gbit/s. An implementation of TCP/IP that uses the features provided by Afterburner to reduce the movement of data to a single copy is discussed. Measurements of the end-to-end performance of Afterburner and the single-copy implementation of TCP/IP are presented  相似文献   
83.
Translated from Atomnaya Énergiya, Vol. 66, No. 6, pp. 423–424, June, 1989.  相似文献   
84.
Translated from Atomnaya Énergiya, Vol. 67, No. 3, pp. 215–216, September, 1989.  相似文献   
85.
An algorithm for construction of the reachability domain by the given time instant ? for a nonlinear third order system under the condition of preliminary approach to a predefined point is proposed. All possible cases of location of this point in the motion plane of the system for different values of the time instant ? are studied.  相似文献   
86.
An apparent decrease in total phosphorus concentrations of approximately 4.l μgP/L has been reported recently for the spring values of 1977 and 1978 in Lake Ontario. Investigation of the loading reduction for this period independent of sedimentation factors can account for only 10% of the change. The results indicate that changes in the sedimentation rate of total phosphorus during this period offer an explanation for the majority of the change in concentration.  相似文献   
87.
A fast algorithm is proposed for estimating the auto- and cross-correlation functions of a large signal. The algorithm is based on the sectioning method by the fast Fourier transform. We determine the optimal length of the portion of data read from external memory into RAM which achieves Tmin—a minimum processing time. An estimate of Tmin is obtained.Translated from Kibernetika, No. 3, pp. 78–81, May–June, 1991.  相似文献   
88.
89.
90.
This paper demonstrates the use of computer simulation for topological design and performance engineering of transparent wavelength-division multiplexing metropolitan-area networks. Engineering of these networks involves the study of various transport-layer impairments such as amplifier noise, component ripple, chirp/dispersion, optical crosstalk, waveform distortion due to filter concatenation, fiber nonlinearities, and polarization effects. A computer simulation methodology composed of three main simulation steps is derived and implemented. This methodology obtains performance estimations by applying efficient wavelength-domain simulations on the entire network topology, followed by time-/frequency-domain simulations on selected paths of the network and finally Q-budgeting on an identified worst case path. The above technique provides an efficient tool for topological design and network performance engineering. Accurate simulation models are presented for each of the performance impairments, and the computer simulation methodology is used for the design and engineering of a number of actual metro network architectures  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