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   5157篇
  免费   144篇
  国内免费   63篇
电工技术   166篇
综合类   288篇
化学工业   841篇
金属工艺   69篇
机械仪表   85篇
建筑科学   1300篇
矿业工程   314篇
能源动力   188篇
轻工业   169篇
水利工程   56篇
石油天然气   38篇
武器工业   7篇
无线电   437篇
一般工业技术   258篇
冶金工业   239篇
原子能技术   14篇
自动化技术   895篇
  2024年   2篇
  2023年   32篇
  2022年   39篇
  2021年   45篇
  2020年   68篇
  2019年   80篇
  2018年   62篇
  2017年   75篇
  2016年   123篇
  2015年   136篇
  2014年   240篇
  2013年   226篇
  2012年   305篇
  2011年   424篇
  2010年   253篇
  2009年   545篇
  2008年   642篇
  2007年   422篇
  2006年   469篇
  2005年   330篇
  2004年   166篇
  2003年   147篇
  2002年   92篇
  2001年   88篇
  2000年   62篇
  1999年   61篇
  1998年   37篇
  1997年   47篇
  1996年   26篇
  1995年   24篇
  1994年   15篇
  1993年   13篇
  1992年   10篇
  1991年   7篇
  1990年   5篇
  1989年   9篇
  1988年   1篇
  1987年   3篇
  1986年   4篇
  1985年   6篇
  1984年   8篇
  1983年   3篇
  1982年   1篇
  1981年   1篇
  1980年   1篇
  1979年   3篇
  1976年   2篇
  1971年   1篇
  1970年   1篇
  1964年   2篇
排序方式: 共有5364条查询结果,搜索用时 15 毫秒
91.
Consideration was given to the BMAP/G/1/∞ single-server queuing system with batch Markov arrivals, arbitrary servicing, finite-capacity buffer, and last come first served probabilistic priority. Equations for determination of the stationary probabilities of states and stationary characteristics associated with the time of customer sojourn in the system were determined.  相似文献   
92.
A class of bilinear systems of integral Volterra equations of the first kind related to the problem of automatic control of a nonlinear dynamic system (object) with unknown structure and vector input and output is studied. Algorithms for an analytic solution to corresponding bilinear systems and its numerical approximation are developed. A special character of the algorithms is illustrated by model examples.  相似文献   
93.
Consistency constraints and 3D building reconstruction   总被引:2,自引:0,他引:2  
Virtual architectural (indoor) scenes are often modeled in 3D for various types of simulation systems. For instance, some authors propose methods dedicated to lighting, heat transfer, acoustic or radio-wave propagation simulations. These methods rely in most cases on a volumetric representation of the environment, with adjacency and incidence relationships. Unfortunately, many buildings data are only given by 2D plans and the 3D needs varies from one application to another. To face these problems, we propose a formal representation of consistency constraints dedicated to building interiors and associated with a topological model. We show that such a representation can be used for: (i) reconstructing 3D models from 2D architectural plans (ii) detecting automatically geometrical, topological and semantical inconsistencies (iii) designing automatic and semi-automatic operations to correct and enrich a 2D plan. All our constraints are homogeneously defined in 2D and 3D, implemented with generalized maps and used in modeling operations. We explain how this model can be successfully used for lighting and radio-wave propagation simulations.  相似文献   
94.
We consider the identically singular Lagrange problem of the calculus of variations. It is investigated how the conjugate points and the Jacobi equation index are related to the solvability conditions of the appropriate matrix Riccati equation and the reducibility of the functional to a perfect square. The criterion of the trajectory variation smallness at a small variation of the functional in the neighborhood of the extremal is obtained.  相似文献   
95.
The paper is devoted to developing methods for control of ecological-economic systems consisting of three hierarchically subordinate subjects of control. In describing the dynamics of a system state, equations in partial derivatives that are solved numerically according to a semi-implicit scheme of the finite-difference method are used. To achieve its main goal (maintenance of an ecological subsystem in stable state), the subject of control of the upper level applies different control methods. Methods of hierarchical control (motivation, enforcement, and persuasion) that differ in the direction of action (on the objective function or domain of admissible controls) are proposed; examples of their use are represented and a comparative analysis of the obtained results is made.  相似文献   
96.
Consideration was given to minimization of the L 1-norm of control of the linear oscillatory system. For consumption of the energy resources required to damp oscillations, bilateral estimates were obtained.  相似文献   
97.
98.
This paper presents a new approach to Particle Swarm Optimization, called Michigan Approach PSO (MPSO), and its application to continuous classification problems as a Nearest Prototype (NP) classifier. In Nearest Prototype classifiers, a collection of prototypes has to be found that accurately represents the input patterns. The classifier then assigns classes based on the nearest prototype in this collection. The MPSO algorithm is used to process training data to find those prototypes. In the MPSO algorithm each particle in a swarm represents a single prototype in the solution and it uses modified movement rules with particle competition and cooperation that ensure particle diversity. The proposed method is tested both with artificial problems and with real benchmark problems and compared with several algorithms of the same family. Results show that the particles are able to recognize clusters, find decision boundaries and reach stable situations that also retain adaptation potential. The MPSO algorithm is able to improve the accuracy of 1-NN classifiers, obtains results comparable to the best among other classifiers, and improves the accuracy reported in literature for one of the problems.
Pedro IsasiEmail:
  相似文献   
99.
We demonstrate a neurocomputing system incorporating an amoeboid unicellular organism, the true slime mold Physarum, known to exhibit rich spatiotemporal oscillatory behavior and sophisticated computational capabilities. Introducing optical feedback applied according to a recurrent neural network model, we induce that the amoeba’s photosensitive branches grow or degenerate in a network-patterned chamber in search of an optimal solution to the traveling salesman problem (TSP), where the solution corresponds to the amoeba’s stably relaxed configuration (shape), in which its body area is maximized while the risk of being illuminated is minimized.Our system is capable of reaching the optimal solution of the four-city TSP with a high probability. Moreover, our system can find more than one solution, because the amoeba can coordinate its branches’ oscillatory movements to perform transitional behavior among multiple stable configurations by spontaneously switching between the stabilizing and destabilizing modes. We show that the optimization capability is attributable to the amoeba’s fluctuating oscillatory movements. Applying several surrogate data analyses, we present results suggesting that the amoeba can be characterized as a set of coupled chaotic oscillators.
Kazuyuki AiharaEmail:
  相似文献   
100.
Zusammenfassung  Nachdruck eines Aufsatzes aus elektronische datenverarbeitung 11(11)1969:544–548. This article is also available in English via and : Grochla E (2008) Corporate Information Systems Engineering and Business and Information Systems Engineering as a Necessary Application-Oriented Extension of General Computer Science – Proposals for Enhancing Academic Education in the Field of Automated Data Processing in the Federal Republic of Germany. Bus Inf Syst Eng. doi .
  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