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   85328篇
  免费   1097篇
  国内免费   407篇
电工技术   807篇
综合类   2320篇
化学工业   11814篇
金属工艺   4809篇
机械仪表   3039篇
建筑科学   2250篇
矿业工程   567篇
能源动力   1144篇
轻工业   3769篇
水利工程   1275篇
石油天然气   342篇
无线电   9394篇
一般工业技术   16506篇
冶金工业   3011篇
原子能技术   263篇
自动化技术   25522篇
  2023年   36篇
  2022年   35篇
  2021年   84篇
  2020年   59篇
  2019年   47篇
  2018年   14487篇
  2017年   13413篇
  2016年   10012篇
  2015年   640篇
  2014年   310篇
  2013年   270篇
  2012年   3201篇
  2011年   9483篇
  2010年   8322篇
  2009年   5591篇
  2008年   6809篇
  2007年   7816篇
  2006年   144篇
  2005年   1233篇
  2004年   1153篇
  2003年   1197篇
  2002年   562篇
  2001年   117篇
  2000年   209篇
  1999年   81篇
  1998年   170篇
  1997年   94篇
  1996年   104篇
  1995年   55篇
  1994年   31篇
  1993年   36篇
  1992年   33篇
  1991年   40篇
  1988年   31篇
  1986年   23篇
  1985年   25篇
  1976年   24篇
  1969年   32篇
  1968年   46篇
  1967年   38篇
  1966年   43篇
  1965年   45篇
  1963年   28篇
  1960年   31篇
  1959年   35篇
  1958年   38篇
  1957年   36篇
  1956年   36篇
  1955年   63篇
  1954年   71篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
1.
International Journal of Computer Vision - Anticipating future situations from streaming sensor data is a key perception challenge for mobile robotics and automated vehicles. We address the problem...  相似文献   
2.
Mobile software applications have to cope with a particular environment that involves small size, limited resources, high autonomy requirements, competitive business models and many other challenges. To provide development guidelines that respond to these needs, several practices have been introduced; however, it is not clear how these guidelines may contribute to solve the issues present in the mobile domain. Furthermore, the rapid evolution of the mobile ecosystem challenges many of the premises upon which the proposed practices were designed. In this paper, we present a survey of the literature on software assurance practices for mobile applications, with the objective of describing them and assessing their contribution and success. We identified, organized and reviewed a body of research that spans in three levels: software development processes, software product assurance practices, and software implementation practices. By carrying out this literature survey, we reviewed the different approaches that researchers on Software Engineering have provided to address the needs that raise in the mobile software development arena. Moreover, we review the evolution of these practices, identifying how the constant changes and modernization of the mobile execution environment has impacted the methods proposed in the literature. Finally, we introduced discussion on the application of these practices in a real productive setting, opening an area for further research that may determine if practitioners have followed the proposed assurance paradigms.  相似文献   
3.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials.  相似文献   
4.
The enzymatic conversion of lignins, possibly in combination with electrochemical oxidation, makes aromatics such as syringol, guaiacol, vanillin and catechol available in the qualities required by the fragrance industry. The lignins were obtained by soda digestion from wheat straw and Miscanthus, characterized and then converted with laccases. The overall yield amounted up to 9 wt % with a product spectrum confined to four substances. Catechol was the major product, with a fraction of ≈75 %. It can easily be isolated by extraction with acetone.  相似文献   
5.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards.  相似文献   
6.
7.
8.
Variations of Incomplete Open Cubes is the major project by the twentieth-century conceptual artist Sol LeWitt. In this paper we interpret the enumerative component of the project as embeddings of graphs. This formulation permits use of an algorithm to check the completeness of the list of the structures produced by the artist. Our conclusion is that the artist found the correct number of structures (that is, 122), but that his list contains a mistake in the presentation of a pair of incomplete cubes, a discovery that appears not to have been noted before.  相似文献   
9.
10.
Thermogravimetric analysis of a coccolith-containing biogenic broth showed a three-step degradation process. According to this system behavior, the biogenic broth was heated to specific temperatures and characterized in terms of its morphology, surface chemistry, and crystallinity. The elemental and organic composition of the treated samples was also evaluated and compared to the reference material. The presented results were acquired in an effort to exploit pretreatment scenarios for such a biogenic system that would improve and support a separation process.  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