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   36607篇
  免费   1305篇
  国内免费   63篇
电工技术   378篇
综合类   29篇
化学工业   7285篇
金属工艺   729篇
机械仪表   744篇
建筑科学   1969篇
矿业工程   114篇
能源动力   1061篇
轻工业   2911篇
水利工程   432篇
石油天然气   120篇
武器工业   5篇
无线电   2495篇
一般工业技术   6170篇
冶金工业   6667篇
原子能技术   270篇
自动化技术   6596篇
  2023年   217篇
  2022年   445篇
  2021年   684篇
  2020年   466篇
  2019年   623篇
  2018年   786篇
  2017年   701篇
  2016年   837篇
  2015年   761篇
  2014年   1046篇
  2013年   2387篇
  2012年   1690篇
  2011年   2100篇
  2010年   1663篇
  2009年   1556篇
  2008年   1813篇
  2007年   1784篇
  2006年   1606篇
  2005年   1446篇
  2004年   1184篇
  2003年   1130篇
  2002年   1058篇
  2001年   710篇
  2000年   557篇
  1999年   601篇
  1998年   608篇
  1997年   586篇
  1996年   560篇
  1995年   580篇
  1994年   527篇
  1993年   512篇
  1992年   502篇
  1991年   289篇
  1990年   420篇
  1989年   391篇
  1988年   320篇
  1987年   357篇
  1986年   313篇
  1985年   420篇
  1984年   420篇
  1983年   319篇
  1982年   295篇
  1981年   284篇
  1980年   270篇
  1979年   270篇
  1978年   248篇
  1977年   228篇
  1976年   207篇
  1975年   194篇
  1974年   173篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Galzigna  Lauro  Sartorelli  Lodovico  Rossi  Carlo R.  Gibson  David M. 《Lipids》1969,4(6):459-461
The enzymic activity of the GTP-dependent acyl-CoA synthase isolated from rat liver mitochondria is affected by removal and addition of lecithin (3). Purified preparations of this enzyme contain bound lecithin. In this presentation the nature of the lecithin-protein interaction is examined. From binding measurements at different temperatures it is possible to postulate which type of secondary valence bonds is holding the protein and lecithin together. Presented at AOCS Meeting, Chicago, October 1967.  相似文献   
102.
The mechanisms and kinetics of radical entry in emulsion polymerizations utilizing redox initiation are investigated using polymerization rate data obtained by reaction calorimetry and electrospray mass spectroscopy analysis of initiator-derived aqueous-phase products. These data have been used to evaluate an initiation scheme for redox-initiated emulsion polymerizations of common monomers such as styrene and methyl methacrylate based around the oxidant, tert-butyl hydroperoxide. Redox initiators are broadly classed by the solubility of their radical products: Hydrophilic radicals enter by propagating to a critical degree of polymerization to become surface-active whilst more hydrophobic radicals may enter particles directly. When direct entry is applicable (the hydrophobic case), initiation efficiency will always be very high.  相似文献   
103.
104.
Liu  Xinke  Kao  Evan  Haraldsson  Henrik  Ballweber  Megan  Martin  Alastair  Li  Youxiang  Wang  Yuting  Saloner  David 《Magma (New York, N.Y.)》2021,34(5):659-666
Magnetic Resonance Materials in Physics, Biology and Medicine - To determine the intra-individual flow variation in serially acquired studies, and the influence of this variation on subsequent...  相似文献   
105.
The rapid growth of video data demands both effective and efficient video summarization methods so that users are empowered to quickly browse and comprehend a large amount of video content. In this paper, we formulate the video summarization task with a novel minimum sparse reconstruction (MSR) problem. That is, the original video sequence can be best reconstructed with as few selected keyframes as possible. Different from the recently proposed convex relaxation based sparse dictionary selection method, our proposed method utilizes the true sparse constraint L0 norm, instead of the relaxed constraint L2,1L2,1 norm, such that keyframes are directly selected as a sparse dictionary that can well reconstruct all the video frames. An on-line version is further developed owing to the real-time efficiency of the proposed MSR principle. In addition, a percentage of reconstruction (POR) criterion is proposed to intuitively guide users in obtaining a summary with an appropriate length. Experimental results on two benchmark datasets with various types of videos demonstrate that the proposed methods outperform the state of the art.  相似文献   
106.
107.
108.
There is a rich variety of physics underlying the fundamental gating operations for quantum information processing (QIP). A key aspect of a QIP system is how noise may enter during quantum operations and how suppressing or correcting its effects can best be addressed. Quantum control techniques have been developed to specifically address this effort, although a detailed classification of the compatibility of controls schemes with noise sources found in common quantum systems has not yet been performed. This work numerically examines the performance of modern control methods for suppressing decoherence in the presence of noise forms found in viable quantum systems. The noise-averaged process matrix for controlled one-qubit and two-qubit operations are calculated across noise found in systems driven by Markovian open quantum dynamics. Rather than aiming to describe the absolute best control scheme for a given physical circumstance, this work serves instead to classify quantum control behavior across a large class of noise forms so that opportunities for improving QIP performance may be identified.  相似文献   
109.
110.
Recommendations in location-based social networks: a survey   总被引:2,自引:0,他引:2  
  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