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   8277篇
  免费   263篇
  国内免费   8篇
电工技术   62篇
综合类   18篇
化学工业   1945篇
金属工艺   185篇
机械仪表   159篇
建筑科学   333篇
矿业工程   27篇
能源动力   242篇
轻工业   746篇
水利工程   136篇
石油天然气   24篇
无线电   499篇
一般工业技术   1754篇
冶金工业   1207篇
原子能技术   21篇
自动化技术   1190篇
  2024年   98篇
  2023年   77篇
  2022年   142篇
  2021年   221篇
  2020年   202篇
  2019年   223篇
  2018年   222篇
  2017年   208篇
  2016年   257篇
  2015年   192篇
  2014年   319篇
  2013年   570篇
  2012年   468篇
  2011年   676篇
  2010年   453篇
  2009年   424篇
  2008年   475篇
  2007年   440篇
  2006年   366篇
  2005年   327篇
  2004年   267篇
  2003年   251篇
  2002年   229篇
  2001年   115篇
  2000年   104篇
  1999年   103篇
  1998年   92篇
  1997年   92篇
  1996年   79篇
  1995年   86篇
  1994年   81篇
  1993年   56篇
  1992年   67篇
  1991年   27篇
  1990年   32篇
  1989年   42篇
  1988年   42篇
  1987年   40篇
  1986年   35篇
  1985年   54篇
  1984年   45篇
  1983年   41篇
  1982年   40篇
  1981年   25篇
  1980年   28篇
  1979年   20篇
  1978年   21篇
  1977年   18篇
  1976年   17篇
  1975年   11篇
排序方式: 共有8548条查询结果,搜索用时 0 毫秒
11.
We present a vision- and ladar-based approach to autonomous driving on rural and desert roads that has been tested extensively in a closed-loop system. The vision component uses Gabor wavelet filters for texture analysis to find ruts and tracks from which the road vanishing point can be inferred via Hough-style voting, yielding a direction estimate for steering control. The ladar component projects detected obstacles along the road direction onto the plane of the front of the vehicle and tracks the 1-D obstacle “gap” presumed due to the road to yield a lateral offset estimate. Several image- and state-based tests to detect failure conditions such as off-road poses (i.e., there is no road to follow) and poor lighting due to sun glare or distracting shadows are also explained. The system’s efficacy is demonstrated with analysis of diverse logged data including from the 2005 DARPA Grand Challenge, as well as tests with full control of a vehicle over 15 km of difficult roads at up to 37 km/h with no waypoints.
Christopher RasmussenEmail:
  相似文献   
12.
With IPv6 transitioning still in a relative state of flux, the need has emerged for methods to control this crucial aspect of IPv6 deployments. This article makes the case for transitioning architectures as a realistic solution to this issue, specifically within large-scale networks. The Site Transitioning Architecture (STA) supports the deployment, operation, and management of IPv6 transitioning mechanisms. The authors provide an overview of the STA's design and operation, noting that its flexible, simple, and secure architecture is suitable for the duration of the IPv6 deployment process, regardless of the underlying network environment.  相似文献   
13.
14.
15.
16.
A new instrument was constructed to perform discrete retardance nonlinear optical ellipsometry (DR-NOE). The focus of the design was to perform second harmonic generation NOE while maximizing sample and application flexibility and minimizing data acquisition time. The discrete retardance configuration results in relatively simple computational algorithms for performing nonlinear optical ellipsometric analysis. NOE analysis of a disperse red 19 monolayer yielded results that were consistent with previously reported values for the same surface system, but with significantly reduced acquisition times.  相似文献   
17.
Using fluorescence in situ hybridization technique, expression of three oncogenes, C-myc, RARa, and cyclin-D was tested on a uterine leiomyoma. C-myc and RARa were amplified in approximately 30% and 90% of the cells, respectively. Numerous small signals of C-myc were indicative of the presence of double minutes. Amplification of RARa is being reported for the first time in a leiomyoma. Cyclin-D was normal in diploid cells while it was highly amplified in polyploid cells. Low levels of amplified C-myc and cyclin-D cells seem to be the reason for this tumor to be benign, while RARa could not be effective without the association of some other gene such as PML. Information presented here are significant toward developing new curative strategies such as gene-specific drugs and molecular manipulation to stop the activity of cancer gene. Further study may elucidate that how fibroids grow and maintain their rare benign nature.  相似文献   
18.
Peg Solitaire is a well known puzzle, which can prove difficult despite its simple rules. Pegs are arranged on a board such that at least one ‘hole’ remains. By making draughts/checkers-like moves, pegs are gradually removed until no further moves are possible or some goal configuration is achieved. This paper considers the English variant, consisting of a board in a cross shape with 33 holes. Modelling Peg Solitaire via constraint or integer programming techniques presents a considerable challenge and is examined in detail. The merits of the resulting models are discussed and they are compared empirically. The sequential nature of the puzzle naturally conforms to a planning problem, hence we also present an experimental comparison with several leading AI planning systems. Other variants of the puzzle, such as ‘Fool's Solitaire’ and ‘Long-hop’ Solitaire are also considered.  相似文献   
19.
Describes 5 means of maintaining standards for psychological practice that are currently used in the US: (1) general and criminal law, (2) peer control, (3) federal regulations, (4) state boards of examiners in psychology, and (5) civil malpractice litigation. Their relevance to the Canadian context is discussed, especially with respect to the more restricted role of the Canadian federal government in professional affairs, the lower profile for civil rights, and the lower incidence of civil litigation in Canada. Recommendations made to ensure the exemplary practice of psychology include the increased use of peer control through peer review committees, increased organization of professional practice at the national level, and a closer liaison between professional associations and governing boards at the provincial level. (7 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
20.
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