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   249235篇
  免费   1680篇
  国内免费   265篇
电工技术   4043篇
综合类   91篇
化学工业   40383篇
金属工艺   15152篇
机械仪表   10064篇
建筑科学   4178篇
矿业工程   3759篇
能源动力   3881篇
轻工业   9700篇
水利工程   4087篇
石油天然气   13006篇
武器工业   28篇
无线电   20287篇
一般工业技术   62802篇
冶金工业   32147篇
原子能技术   11135篇
自动化技术   16437篇
  2021年   2758篇
  2019年   2736篇
  2018年   5436篇
  2017年   5713篇
  2016年   6053篇
  2015年   3053篇
  2014年   5328篇
  2013年   10091篇
  2012年   7316篇
  2011年   8939篇
  2010年   7302篇
  2009年   8109篇
  2008年   8177篇
  2007年   7870篇
  2006年   6370篇
  2005年   5572篇
  2004年   5484篇
  2003年   5307篇
  2002年   5141篇
  2001年   4950篇
  2000年   4940篇
  1999年   4254篇
  1998年   7173篇
  1997年   5832篇
  1996年   4429篇
  1995年   3661篇
  1994年   3425篇
  1993年   3625篇
  1992年   3216篇
  1991年   3364篇
  1990年   3484篇
  1989年   3372篇
  1988年   3267篇
  1987年   3262篇
  1986年   3164篇
  1985年   3339篇
  1984年   3259篇
  1983年   3159篇
  1982年   3001篇
  1981年   3047篇
  1980年   3071篇
  1979年   3257篇
  1978年   3492篇
  1977年   3461篇
  1976年   3913篇
  1975年   3210篇
  1974年   3293篇
  1973年   3342篇
  1972年   2988篇
  1971年   2754篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Pham  V.D. Vu  T.B. 《Electronics letters》1998,34(5):427-428
The authors present an adaptive space-time reduced-length minimum mean-squared error (MMSE) receiver to suppress co-channel interference in the near-far environment for an asynchronous direct-sequence code-division multiple-access (DS/CDMA) system. Simulation results show that better bit-error rate and faster and more stable convergence are achieved over the existing full- and reduced-length MMSE receivers  相似文献   
992.
993.
The paper describes the development of a software design aid for use at the conceptual stage of engineering design. It is intended for use in the design of mechatronic products but has wider potential uses. Early approaches were based on function structures and tables of options and the system that evolved allows the assembly of schemes linked by matching their input and output ports. A database of components is provided which can be accessed via different indexes and the designer can easily create and compare alternative schemes at the concept stage.A bond graph approach is used to define the interconnections between components. This allows correct port matching but also provides for future development such as constraint propagation through the design and links to simulation tools.  相似文献   
994.
995.
A method for identifying a set of candidate words that matches well with a given utterance is discussed. The method uses precomputed groups of acoustically similar words. Given a vocabulary, for each word a short list of words that are acoustically similar to it is computed. These groups are constructed using training utterances recorded by several speakers and used in an isolated utterance recognition system to construct candidate word lists during recognition. Experiments show that the correct word appears on the short list of candidate words constructed during recognition using this scheme over 98% of the time  相似文献   
996.
The matrix pencil (MP) method, based on the singular value decomposition (SVD), is applied to quantitative NMR spectroscopy. Its relationship to other SVD-based methods is also presented. Simulations and applications are given to demonstrate the capability of superior performance.©1993 John Wiley & Sons Inc  相似文献   
997.
Institute of Rock Mechanics, Academy of Sciences of the USSR, Moscow. Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 1, pp. 39–44, January-February, 1992.  相似文献   
998.
The influence of the structure and crystallographic texture of VT3-1 alloy formed by thermomechanical processing of a forging and also of the production factors of subsequent production of a gas turbine engine blade from the forging on the fatigue resistance characteristics was investigated. It was established that the reason for the reduction in fatigue limit and the significant spread in test data is nonuniformity of the structure and texture, both in different forgings and within the same forging, caused by variations in such parameters of thermomechanical processing as the temperature and degree of deformation. The nonuniformity plays a determining role in the reduction in fatigue limit as the result of hydrogen absorption during chemical etching. It was shown that such an effect may be eliminated by degassing vacuum annealing and the general level of fatigue resistance characteristics may be increased as the result of thermomechanical processing of forgings with strict observance of the specified forging temperature.Translated from Problemy Prochnosti, No. 6, pp. 12–19, June, 1992.  相似文献   
999.
1000.
Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 4, pp. 32–33, April, 1991.  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