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   83234篇
  免费   340篇
  国内免费   64篇
电工技术   1880篇
综合类   96篇
化学工业   10793篇
金属工艺   7261篇
机械仪表   6168篇
建筑科学   1538篇
矿业工程   817篇
能源动力   891篇
轻工业   1523篇
水利工程   1206篇
石油天然气   1548篇
无线电   8000篇
一般工业技术   21794篇
冶金工业   6487篇
原子能技术   1157篇
自动化技术   12479篇
  2023年   68篇
  2022年   125篇
  2021年   228篇
  2020年   143篇
  2019年   118篇
  2018年   9456篇
  2017年   10120篇
  2016年   5308篇
  2015年   692篇
  2014年   239篇
  2013年   244篇
  2012年   3035篇
  2011年   9325篇
  2010年   8906篇
  2009年   7581篇
  2008年   7245篇
  2007年   9508篇
  2006年   128篇
  2005年   4072篇
  2004年   2272篇
  2003年   1877篇
  2002年   744篇
  2001年   79篇
  2000年   161篇
  1999年   33篇
  1998年   21篇
  1997年   14篇
  1996年   25篇
  1995年   21篇
  1994年   36篇
  1993年   34篇
  1992年   22篇
  1991年   29篇
  1969年   56篇
  1968年   127篇
  1967年   117篇
  1966年   144篇
  1965年   123篇
  1964年   80篇
  1963年   64篇
  1962年   66篇
  1961年   71篇
  1960年   89篇
  1959年   62篇
  1958年   76篇
  1957年   128篇
  1956年   119篇
  1955年   139篇
  1954年   153篇
  1951年   16篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The Markov properties of the solutions of Ito-Skorokhod stochastic functional-differential equations (SFDEs) with entire prehistory are considered, the concept of a weak infinitesimal operator is introduced for a Markov process that is a solution of an SFDE, and the strong solution of the SFDE is analyzed for stability. Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 123–134, January–February 2009.  相似文献   
992.
We propose a modification of the additive splitting algorithm to solve the convection-diffusion problem using an efficient finite-difference scheme. The modification decreases the number of data exchanges and their amount during the numerical solution of a system of multidimensional equations. Approximation, stability, and convergence are considered. Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 100–107, January–February 2009.  相似文献   
993.
The problem-solving time and the solution accuracy are expressed as functions of a parameter. An optimization problem of choosing the parameter using a “time cost–solution accuracy” criterion is considered. A Pareto-optimal set of solutions is obtained. The best value of the parameter is chosen by the ideal-point method. Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 98–105, July–August 2009.  相似文献   
994.
The key results in the standardization of system and software engineering in Ukraine are outlined and rationales of the national standardization approaches in this field are presented. All the current national standards in software engineering are reviewed.  相似文献   
995.
The parameter identification problem for the nonlinear dynamic system of a sufficiently general form, in which the multipolynomial approximation algorithm processes measured data, is considered. To show the efficiency of the algorithm, an example of parameter identification for a nonlinear dynamic system with non-differentiable right-hand side is given and the identification problem for aerodynamic parameters of aircraft pitching motion is solved.  相似文献   
996.
A linear non-stationary conflict-interaction problem for controlled objects with n pursuers and m evaders with equal dynamical potency of each participant is considered. The objective of the pursuers is to capture all the evaders; the objective of the evaders is to avoid overtaking of at least one of them. Sufficient conditions for the global evasion problem solvability are stated.  相似文献   
997.
An autonomous navigation system for near-Earth spacecraft is described; this system allows determination of the satellite orbit and prediction of its motion parameters. Radio navigation measurements of GLONASS and GPS satellite systems are used for this purpose. The autonomous navigation system is designated for operation on near-Earth orbits which do not go beyond the navigation areas of GLONASS and/or GPS and on orbits with large eccentricity whose apocenter is at a distance of 50–70 thousand km from the Earth’s surface. The developed methods and algorithms for orbit determination are based on the application of laws of motion dynamics of a spacecraft directly at processing primary phase measurements of the carrier frequency and code pseudo-range using an extended measurement base. Algorithms for determination of motion parameters of the spacecraft and results of simulation and operation of a model system are presented. The possibility of creation of an onboard autonomous navigation system with precision and reliability higher than those of the ground measuring complex is demonstrated.  相似文献   
998.
An optimal guaranteed control problem for electromechanical manipulator with the goal of finding an immovable or mobile target objects is considered. Unlike [1–6], as the optimality criterion, a functional taking into account power inputs of the light source on the gripper of the manipulator is taken. The sought object is assumed to be detected if it falls into the light circle with given illumination. The control algorithms of the gripper motion and corresponding laws of electric current variation in the light source circuit providing the detection of both immovable and mobile sought object in a guaranteed time for minimal light power inputs during the search are developed. The gain in light power inputs achieved for the proposed search algorithms is estimated.  相似文献   
999.
FALGOL (Formal ALGOrithmic Language) is a fundamental theoretical model of high-level operational languages with unrestricted program object hierarchy. This model formalizes binding, assignment, substitution, and recursion; moreover, the principle of dynamic binding is implemented in the model in contrast to other formal systems of this sort, which makes FALGOL appropriate to specify the most difficultly formalized concepts in modern object programming languages.  相似文献   
1000.
The problem of fault accommodation in nonlinear dynamic systems is solved by constructing a control law that provides full decoupling with respect to fault effects. Existence conditions are found, and calculating relations are given for the control law.  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