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   15218篇
  免费   1104篇
  国内免费   120篇
电工技术   232篇
综合类   65篇
化学工业   3929篇
金属工艺   371篇
机械仪表   560篇
建筑科学   561篇
矿业工程   23篇
能源动力   1111篇
轻工业   1472篇
水利工程   199篇
石油天然气   252篇
武器工业   4篇
无线电   1540篇
一般工业技术   2891篇
冶金工业   541篇
原子能技术   110篇
自动化技术   2581篇
  2024年   69篇
  2023年   323篇
  2022年   634篇
  2021年   1022篇
  2020年   843篇
  2019年   915篇
  2018年   1024篇
  2017年   923篇
  2016年   926篇
  2015年   546篇
  2014年   871篇
  2013年   1543篇
  2012年   1011篇
  2011年   1048篇
  2010年   741篇
  2009年   665篇
  2008年   470篇
  2007年   397篇
  2006年   339篇
  2005年   216篇
  2004年   195篇
  2003年   168篇
  2002年   134篇
  2001年   106篇
  2000年   96篇
  1999年   93篇
  1998年   153篇
  1997年   120篇
  1996年   109篇
  1995年   73篇
  1994年   59篇
  1993年   68篇
  1992年   57篇
  1991年   43篇
  1990年   45篇
  1989年   34篇
  1988年   28篇
  1987年   26篇
  1986年   37篇
  1985年   30篇
  1984年   30篇
  1983年   27篇
  1982年   21篇
  1981年   20篇
  1980年   19篇
  1979年   17篇
  1978年   19篇
  1977年   20篇
  1976年   25篇
  1975年   13篇
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
31.
Wireless Networks - The original version of this article unfortunately contained a mistake in the title. The correct title has been published with this erratum.  相似文献   
32.
Multimedia Tools and Applications - The world is facing many problems including that of traffic congestion. To highlight the issue of traffic congestion worldwide specially in urban areas and to...  相似文献   
33.
The potential energy profile of the reaction between dimethyl disulfide and OH? radicals is explored by utilizing ab initio and hybrid meta density functional theory methods. Having the energies and structural data of the stationary points, statistical rate theories, such as transition state theory and variable reaction coordinate-transition state theory, are employed to compute the overall rate constants, and discuss the mechanism and product channels. On the basis of the calculations, the overall rate coefficient is predicted to be 2.49?×?10?10?cm3?molecule?1?s?1 at 298?K. It is found that in the most favorable pathway, the reaction proceeds via formation of the relatively unstable intermediate CH3S?(OH)SCH3 decomposing rapidly to yield CH3S?+CH3SOH.  相似文献   
34.
The case-based learning (CBL) approach has gained attention in medical education as an alternative to traditional learning methodology. However, current CBL systems do not facilitate and provide computer-based domain knowledge to medical students for solving real-world clinical cases during CBL practice. To automate CBL, clinical documents are beneficial for constructing domain knowledge. In the literature, most systems and methodologies require a knowledge engineer to construct machine-readable knowledge. Keeping in view these facts, we present a knowledge construction methodology (KCM-CD) to construct domain knowledge ontology (i.e., structured declarative knowledge) from unstructured text in a systematic way using artificial intelligence techniques, with minimum intervention from a knowledge engineer. To utilize the strength of humans and computers, and to realize the KCM-CD methodology, an interactive case-based learning system(iCBLS) was developed. Finally, the developed ontological model was evaluated to evaluate the quality of domain knowledge in terms of coherence measure. The results showed that the overall domain model has positive coherence values, indicating that all words in each branch of the domain ontology are correlated with each other and the quality of the developed model is acceptable.  相似文献   
35.
A new, efficient and recoverable heterogeneous catalyst was successfully synthesized by functionalization of mesoporous silica FSM-16. The FSM-16/CPTMS-Rh-  相似文献   
36.
Neural Computing and Applications - To obtain the optimal set of features in feature selection problems is the most challenging and prominent problem in machine learning. Very few human-related...  相似文献   
37.
Highly accurate real‐time localization is of fundamental importance for the safety and efficiency of planetary rovers exploring the surface of Mars. Mars rover operations rely on vision‐based systems to avoid hazards as well as plan safe routes. However, vision‐based systems operate on the assumption that sufficient visual texture is visible in the scene. This poses a challenge for vision‐based navigation on Mars where regions lacking visual texture are prevalent. To overcome this, we make use of the ability of the rover to actively steer the visual sensor to improve fault tolerance and maximize the perception performance. This paper answers the question of where and when to look by presenting a method for predicting the sensor trajectory that maximizes the localization performance of the rover. This is accomplished by an online assessment of possible trajectories using synthetic, future camera views created from previous observations of the scene. The proposed trajectories are quantified and chosen based on the expected localization performance. In this study, we validate the proposed method in field experiments at the Jet Propulsion Laboratory (JPL) Mars Yard. Furthermore, multiple performance metrics are identified and evaluated for reducing the overall runtime of the algorithm. We show how actively steering the perception system increases the localization accuracy compared with traditional fixed‐sensor configurations.  相似文献   
38.
39.
40.
Thermal bending analysis of doubly curved laminated shell panels with general boundary conditions and laminations is presented. The equations of equilibrium are derived in the form of two coupled sets of ordinary differential equations based on a general shell theory and solved through the state-space approach in a repeated manner. It is depicted that the results of the present method are in great agreement with analytical solutions. Cylindrical shell panels with general boundary conditions and laminations, where no analytical solution is available, are solved. It is found that the present method exhibits a high convergence rate as well as presenting accurate results in all cases.  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