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   38164篇
  免费   2135篇
  国内免费   63篇
电工技术   261篇
综合类   123篇
化学工业   9027篇
金属工艺   743篇
机械仪表   782篇
建筑科学   1138篇
矿业工程   90篇
能源动力   1023篇
轻工业   7538篇
水利工程   368篇
石油天然气   252篇
武器工业   2篇
无线电   1699篇
一般工业技术   5854篇
冶金工业   6304篇
原子能技术   168篇
自动化技术   4990篇
  2024年   75篇
  2023年   377篇
  2022年   872篇
  2021年   1318篇
  2020年   920篇
  2019年   1008篇
  2018年   1490篇
  2017年   1472篇
  2016年   1548篇
  2015年   1154篇
  2014年   1543篇
  2013年   3011篇
  2012年   2495篇
  2011年   2468篇
  2010年   1948篇
  2009年   1799篇
  2008年   1676篇
  2007年   1461篇
  2006年   1114篇
  2005年   914篇
  2004年   827篇
  2003年   812篇
  2002年   646篇
  2001年   523篇
  2000年   430篇
  1999年   494篇
  1998年   2221篇
  1997年   1454篇
  1996年   938篇
  1995年   546篇
  1994年   424篇
  1993年   415篇
  1992年   158篇
  1991年   121篇
  1990年   94篇
  1989年   109篇
  1988年   125篇
  1987年   116篇
  1986年   87篇
  1985年   103篇
  1984年   91篇
  1983年   59篇
  1982年   61篇
  1981年   84篇
  1980年   89篇
  1979年   40篇
  1978年   42篇
  1977年   122篇
  1976年   238篇
  1973年   48篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
This paper describes an active model with a robust texture model built on-line. The model uses one camera and it is able to operate without active illumination. The texture model is defined by a series of clusters, which are built in a video sequence using previously encountered samples. This model is used to search for the corresponding element in the following frames. An on-line clustering method, named leaderP is described and evaluated on an application of face tracking. A 20-point shape model is used. This model is built offline, and a robust fitting function is used to restrict the position of the points. Our proposal is to serve as one of the stages in a driver monitoring system. To test it, a new set of sequences of drivers recorded outdoors and in a realistic simulator has been compiled. Experimental results for typical outdoor driving scenarios, with frequent head movement, turns and occlusions are presented. Our approach is tested and compared with the Simultaneous Modeling and Tracking (SMAT) [1], and the recently presented Stacked Trimmed Active Shape Model (STASM) [2], and shows better results than SMAT and similar fitting error levels to STASM, with much faster execution times and improved robustness.  相似文献   
92.
An Analysis of Edge Detection by Using the Jensen-Shannon Divergence   总被引:1,自引:0,他引:1  
This work constitutes a theoretical study of the edge-detection method by means of the Jensen-Shannon divergence, as proposed by the authors. The overall aim is to establish formally the suitability of the procedure of edge detection in digital images, as a step prior to segmentation. In specific, an analysis is made not only of the properties of the divergence used, but also of the method's sensitivity to the spatial variation, as well as the detection-error risk associated with the operating conditions due to the randomness of the spatial configuration of the pixels. Although the paper deals with the procedure based on the Jensen-Shannon divergence, some problems are also related to other methods based on local detection with a sliding window, and part of the study is focused to noisy and textured images.  相似文献   
93.
In this paper, a prototype for progressive transmission of medical digital 2D images through the network, called CASANDRA, is presented. The prototype consists of the server part and the client part. In the server part, the images are acquired, stored, computed their wavelet transform and the wavelet coefficients stored, then transmitted progressively, when required, via TCP to the client. In the client part, with the inverse wavelet transform, the received wavelet coefficients are used to build successive improved reconstructions of the image.This prototype has been implemented and is being tested in the Radiotherapy Service of the Valencia University Hospital (Valencia, Spain).  相似文献   
94.
It is described the case of a patient with Ovarian Cystadenoma in whom a 3.5 cm nodular lesion was accidentally detected in her left suprarenal gland. She had no signs of hypercortisolism or any other suprarenal pathology and was symptomless. Determinations in the urine of 24 hours of Cortisol, Adrenaline and Noradrenaline, 17-ketosteroids and Tetrahydroaldosterone were normal. Daily rhythm and plasmatic determinations of ACTH, cortisol and 11-deoxycortisol were normal. The Dexamethasone suppression test was also normal. In the suprarenal gammagraphy it appeared an intense captation by left suprarenal without visualization of right gland. A left suprarenalectomy was performed and the anatomopathological analysis showed a clear cell corticoadrenal adenoma. Therefore the only data of the function of suprarenal adenoma was the one coming from gammagraphy. We thought that the adenoma was responsible of practically all the corticoadrenal function without reaching pathological levels, meeting the criteria of "pre-Cushing" syndrome or subclinical Cushing, due to the fact that the contralateral gland was not seen in the gammagraphy. Therefore in the characterization of certain tumors which appear clinically and biochemically as non functional, the suprarenal gammagraphy could be a technique of great usefulness for the diagnosis.  相似文献   
95.
96.
The study analyzes variables that influence the water management model based on a simultaneous relationship between competing demands in the Marina Baja of Alicante, using a methodology that directly links together urban and irrigation demands, making them relevant to each other from a socioeconomic point of view. The paper identifies the relevant variables of this model and the agent behaviour in a closed and joint system. It also aims to demonstrate that by considering water demands for different yet simultaneous uses and regarding clean and reclaimed waters as integrated resources, the system could remain in equilibrium without external water supplies.  相似文献   
97.
Two key aspects of the Knowledge Society are the interconnection between the actors involved in the decision making processes and the importance of the human factor, particularly the citizen’s continuous learning and education. This paper presents a new module devoted to knowledge extraction and diffusion that has been incorporated into a previously developed decision making tool concerning the Internet and related with the multicriteria selection of a discrete number of alternatives (PRIOR-Web). Quantitative and qualitative procedures using data and text mining methods have been employed in the extraction of knowledge. Graphical visualisation tools have been incorporated in the diffusion stage of the methodological approach suggested when dealing with decision making in the Knowledge Society. The resulting collaborative platform is being used as the methodological support for the cognitive democracy known as e-cognocracy.  相似文献   
98.
In this paper we deal with the observer-based asymptotic synchronization problem for a class of chaotic oscillators. Some results based on a differential algebraic approach are used in order to determine the algebraic observability of unknown variables. The strategy consists of proposing a slave system (observer) which tends to follow asymptotically the master system. The methodology is tested in the real-time asymptotic synchronization of the Colpitts oscillator by means of a proportional reduced order observer (PROO) of free-model type.  相似文献   
99.
100.
We have found experimentally that rf SQUID's working in a nonhysteretic mode with small critical currents give exactly at resonance and at very low rf bias a triangular pattern with a period equal to half of one elementary quantum of magnetic flux. We discuss a possible explanation of this peculiar result.  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