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   7615篇
  免费   161篇
  国内免费   35篇
电工技术   515篇
综合类   20篇
化学工业   1915篇
金属工艺   202篇
机械仪表   179篇
建筑科学   230篇
矿业工程   1篇
能源动力   298篇
轻工业   644篇
水利工程   27篇
石油天然气   9篇
无线电   615篇
一般工业技术   1296篇
冶金工业   874篇
原子能技术   261篇
自动化技术   725篇
  2023年   35篇
  2022年   76篇
  2021年   132篇
  2020年   67篇
  2019年   81篇
  2018年   105篇
  2017年   94篇
  2016年   150篇
  2015年   107篇
  2014年   183篇
  2013年   414篇
  2012年   241篇
  2011年   407篇
  2010年   330篇
  2009年   356篇
  2008年   389篇
  2007年   340篇
  2006年   262篇
  2005年   282篇
  2004年   249篇
  2003年   217篇
  2002年   205篇
  2001年   151篇
  2000年   133篇
  1999年   165篇
  1998年   388篇
  1997年   238篇
  1996年   196篇
  1995年   121篇
  1994年   130篇
  1993年   149篇
  1992年   88篇
  1991年   123篇
  1990年   84篇
  1989年   101篇
  1988年   91篇
  1987年   62篇
  1986年   109篇
  1985年   84篇
  1984年   72篇
  1983年   81篇
  1982年   84篇
  1981年   71篇
  1980年   61篇
  1979年   59篇
  1978年   55篇
  1977年   46篇
  1976年   44篇
  1975年   24篇
  1973年   25篇
排序方式: 共有7811条查询结果,搜索用时 15 毫秒
91.
In this paper, we propose a novel method to achieve both dense 3D reconstruction of the scene and estimation of the camera intrinsic parameters by using coplanarities and other constraints (e.g., orthogonalities or parallelisms) derived from relations between planes in the scene and reflected curves of line lasers captured by a single camera. In our study, we categorize coplanarities in the scene into two types: implicit coplanarities, which can be observed as reflected curves of line lasers, and explicit coplanarities, which are, for example, observed as walls of a building. By using both types of coplanarities, we can construct simultaneous equations and can solve them up to four degrees of freedom. To upgrade the solution to the Euclidean space and estimate the camera intrinsic parameters, we can use metric constraints such as orthogonalities of the planes. Such metric constraints are given by, for example, observing the corners of rectangular boxes in the scene, or using special laser projecting device composed of two line lasers whose laser planes are configured to be perpendicular.  相似文献   
92.
This article proposes a function for color information detection using genetic programming (GP). In image-processing, object detection is one of the important processes. In cases where the object has a complex color domain, detection becomes more difficult. We generated a detection function for a complex color domain by using GP. The detection function deals with one pixel of an input image, and it obtains an output image by processing for all pixels. We aimed at a reduction in the time taken by a human to consider an image-processing system design. We applied the generation of GP to detect a target color region in actual images. The results show that the detection function has sufficient ability for these detections.  相似文献   
93.
A home network system consists of multiple networked appliances, intended to provide more convenient and comfortable living for home users. Before being deployed, one has to guarantee the correctness, the safety, and the security of the system. Here, we present the approach chosen to validate the Java implementation of a home network system. We rely on the Java Modelling Language to formally specify and validate an abstraction of the system. This is a substantially revised version of our paper that appeared in the proceedings of the Workshop On Leveraging Applications of Formal Methods, Verification and Validation (ISoLA), Poitiers-Futuroscope, France, December 2007.  相似文献   
94.
A novel method for acquiring serial images suitable for three-dimensional reconstruction of vascular networks in the whole brain of mouse was developed. The brain infused with a White India ink-gelatin solution was fixed and embedded in paraffin containing Sudan Black B through xylene also containing Sudan Black B. Each sliced surface of the paraffin block was coated with liquid paraffin and its image was serially acquired. Coating with liquid paraffin extremely improved the quality of the image. The series of serial images was free of distortion and a three-dimensional image was reconstructed without the problem of the alignment and registration of adjacent images. The volume-rendered image indicated three-dimensional distribution of blood vessels in a whole brain. No ghost or shadow was observed on a volume-rendered image of the White India ink-gelatin infused brain. The z-axial resolution examined on the orthogonal sections reconstituted from serial images obtained at an interval of 5 mum showed no cross talk, indicating that the z-axial resolution was no larger than 5 mum. A proper understanding of the vascular system in a whole brain is indispensable to reveal the development of the vascular system in the brain of normal and genetically manipulated mouse and vascular alterations in pathological situation, such as stroke and neurodegenerative disease. Although simple and inexpensive, this method will provide fundamental information on the vascular system in a whole brain.  相似文献   
95.
Honda T  Matsumoto H 《Applied optics》1994,33(20):4475-4479
A reflection-grating self-pumped phase-conjugate mirror is demonstrated with a photorefractive KNbO(3) crystal in a novel ring configuration. The feedback beam in the ring configuration is made to track the input probe beam automatically so that the phase conjugation is sustained without readjustment of the optical feedback loop when the angle or the position of the input probe beam is changed. The tracking feedback is realized by means of a simple three-lens erect imaging system. The angular and the positional acceptances for a tightly focused input beam of 50-μm diameter are Δθ(x). = 55 mrad, Δθ(y), = 67 mrad, and Δ(x) = 2.1 mm, Δ(y) = 4.2 mm, respectively.  相似文献   
96.
Sakano T  Matsumoto T  Noguchi K 《Applied optics》1995,34(11):1815-1822
A prototype multiprocessor system using three-dimensional board-to-board free-space optical interconnects is constructed for the first time to our knowledge. In the system, 64 processing units form a three-dimensional mesh processor network with the help of bidirectional board-to-board free-space optical interconnects. A theoretical analysis shows that the three-dimensional board-to-board freespace optical interconnects effectively solve common interconnection problems such as wiring congestion, signal delay, and clock skew. The prototype system, COSINE-III, is confirmed to work well as a multiprocessor system. The system is also shown to be easy to extend to a larger and more flexible system.  相似文献   
97.
Journal of Infrared, Millimeter, and Terahertz Waves - Millimeter waves (MMW) absorbed by skin or cornea may induce damage by heat. We have developed a 60 GHz MMW exposure-induced eye...  相似文献   
98.
99.
100.
Data concerning the length of longitudinal cracks on the surface of continuously cast steel slabs were collected from two plants. The data were analyzed to find the relation between crack length and crack frequency. The analysis revealed the following.
(1)  After normalization to eliminate the effect of different casting conditions, the fractal relation characterizing the normalized cumulative frequency distribution (N (m−2)) and the crack length (L (mm)) of the primary surface cracks could be represented by the equation
where N c is the cumulative frequency before normalization, γ is the normalizing coefficient, and k c is a constant.
(2)  The values for γ varied over a wide range, but remained constant throughout a heat and were the same for both the upper and lower faces of the slab.
(3)  It was found that in some instances, when L exceeded a critical value (L c), the value of L became δ times longer than the length predicted by the previous distribution. This increase in L was ascribed to secondary growth of the cracks. This occurred more frequently on the lower, rather than on the upper, face of the slab. The product of L c and δ was approximately constant. The formation of the surface cracks is discussed in view of the fractal phenomena.
  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