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   4242篇
  免费   276篇
  国内免费   13篇
电工技术   49篇
化学工业   1280篇
金属工艺   87篇
机械仪表   138篇
建筑科学   141篇
矿业工程   24篇
能源动力   137篇
轻工业   545篇
水利工程   33篇
石油天然气   30篇
武器工业   1篇
无线电   291篇
一般工业技术   749篇
冶金工业   310篇
原子能技术   45篇
自动化技术   671篇
  2024年   10篇
  2023年   56篇
  2022年   176篇
  2021年   217篇
  2020年   142篇
  2019年   149篇
  2018年   184篇
  2017年   166篇
  2016年   175篇
  2015年   143篇
  2014年   199篇
  2013年   347篇
  2012年   252篇
  2011年   308篇
  2010年   211篇
  2009年   203篇
  2008年   192篇
  2007年   163篇
  2006年   139篇
  2005年   123篇
  2004年   86篇
  2003年   70篇
  2002年   68篇
  2001年   49篇
  2000年   41篇
  1999年   46篇
  1998年   86篇
  1997年   57篇
  1996年   43篇
  1995年   40篇
  1994年   35篇
  1993年   37篇
  1992年   20篇
  1991年   18篇
  1990年   15篇
  1989年   18篇
  1988年   16篇
  1987年   28篇
  1986年   16篇
  1985年   16篇
  1984年   13篇
  1983年   10篇
  1982年   16篇
  1981年   9篇
  1979年   14篇
  1978年   10篇
  1976年   14篇
  1975年   9篇
  1973年   14篇
  1972年   8篇
排序方式: 共有4531条查询结果,搜索用时 15 毫秒
271.
This paper presents an approach for the generation of test purposes in the form of labelled transition systems from specifications of properties in CTL. The approach is aimed at adapting the model checking process, by extending search algorithms to perform further analysis so that examples and counter-examples can be extracted. An algorithm for the generation of test purposes through analysis over the examples and counter-examples is presented, along with a case study to show the correspondence between the CTL properties and the generated test purposes.  相似文献   
272.
State estimation problems for linear time-invariant systems with noisy inputs and outputs are considered. An efficient recursive algorithm for the smoothing problem is presented. The equivalence between the optimal filter and an appropriately modified Kalman filter is established. The optimal estimate of the input signal is derived from the optimal state estimate. The result shows that the noisy input/output filtering problem is not fundamentally different from the classical Kalman filtering problem.  相似文献   
273.
This paper proposes a methodology for edge detection in digital images using the Canny detector, but associated with a priori edge structure focusing by a nonlinear anisotropic diffusion via the partial differential equation (PDE). This strategy aims at minimizing the effect of the well-known duality of the Canny detector, under which is not possible to simultaneously enhance the insensitivity to image noise and the localization precision of detected edges. The process of anisotropic diffusion via thePDE is used to a priori focus the edge structure due to its notable characteristic in selectively smoothing the image, leaving the homogeneous regions strongly smoothed and mainly preserving the physical edges, i.e., those that are actually related to objects presented in the image. The solution for the mentioned duality consists in applying the Canny detector to a fine gaussian scale but only along the edge regions focused by the process of anisotropic diffusion via the PDE. The results have shown that the method is appropriate for applications involving automatic feature extraction, since it allowed the high-precision localization of thinned edges, which are usually related to objects present in the image.  相似文献   
274.
PETRI 网在软件过程建模及过程实施中的应用   总被引:2,自引:1,他引:2  
软件过程技术,作为一种保证软件开发质量和效率的方法,在许多软件企业引起了重视和应用。本文从条件/事件网出发,应用标记PETRI网,并针对其在软件过程中的特点,给出了软件过程和软件过程网合理性的定义,根据工作流领域的结论,可以应用经典PETRI网的工具验证其合理性。在此理论基础上,提出了传统的软件过程结构表示成软件过程网的规则。并研究其在实践中的应用,最后用一个实际软件开发企业中的应用实例详细解释了所提出的理论及应用。  相似文献   
275.
The H2-norm control problem of discrete-time Markov jump linear systems is addressed in this paper when part of, or the total of the Markov states is not accessible to the controller. The non-observed part of the Markov states is grouped in a number of clusters of observations; the case with a single cluster retrieves the situation when no Markov state is observed. The control action is provided in linear feedback form, which is invariant on each cluster, and this restricted complexity setting is adopted, aiming at computable solutions. We explore a recent result by de Oliveira, Bernussou, and Geromel (Systems Control Lett. 37 (1999) 261) involving an LMI characterization to establish a H2 solution that is stabilizing in the mean square sense. The novelty of the method is that it can handle in LMI form the situation ranging from no Markov state observation to complete state observation. In addition, when the state observation is complete, the optimal H2-norm solution is retrieved.  相似文献   
276.
This paper focuses on BSR (Broadcasting with Selective Reduction) implementation of algorithms solving basic convex polygon problems. More precisely, constant time solutions on a linear number, max(N, M) (where N and M are the number of edges of the two considered polygons), of processors for computing the maximum distance between two convex polygons, finding critical support lines of two convex polygons, computing the diameter, the width of a convex polygon and the vector sum of two convex polygons are described. These solutions are based on the merging slopes technique using one criterion BSR operations.  相似文献   
277.
The authors calculated the shunt revision rate for 77 consecutive patients with tumoural obstructive hydrocephalus. At a mean follow up of 23.7 months, the annual revision rate was 0.06 which is significantly lower than the annual revision rate of 0.39 for other hydrocephalic patients treated during the same period. Shunted patients who had total excision of their lesions had a significantly lower revision rate than patients who had a partial excision or a biopsy. It is therefore, suggested that cases with tumoural obstructive hydrocephalus may represent a subset of hydrocephalic patients who are associated with a relatively low risk of shunt complications. The observation has to be addressed when the role of endoscopic third ventriculostomy in these patients is being considered.  相似文献   
278.
The radiosity method is particularly suitable for global illumination calculations in static environments. Nonetheless, recent applications of image synthesis such as architectural simulation or lighting design require the ability to modify environments. Previous methods have attempted to deal with dynamic environments (environments where the geometry, the material properties, etc., can change)but still suffer some limitations in the case of moving objects. One of the main problems remaining is the efficient and accurate detection of which form factors must really be recomputed, since their calculation is the most time-consuming part of the radiosity method. To correctly understand and solve this problem, we start with a method in 2D for polygonal scenes using the visibility complex. It is a powerful data structure representing the visibility relationships between objects in the plane. We have developed and implemented an algorithm which uses this structure to efficiently compute the discontinuity mesh and the form factors for static scenes. We also propose an extension to our algorithm to efficiently update only the modified form factors when an object is moving. This approach enhances our understanding and will hopefully lead to efficient solutions in 3D.  相似文献   
279.
280.
V-Effects of thrombolytic therapy on coronary reperfusion and left ventricular function VI-Noninvasive markers of reperfusion. VII-Timing of thrombolysis. VIII-Side effects and adverse outcomes.  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