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   43203篇
  免费   4522篇
  国内免费   2867篇
电工技术   13970篇
技术理论   1篇
综合类   4924篇
化学工业   1676篇
金属工艺   1609篇
机械仪表   4040篇
建筑科学   1094篇
矿业工程   1294篇
能源动力   756篇
轻工业   969篇
水利工程   601篇
石油天然气   847篇
武器工业   626篇
无线电   4129篇
一般工业技术   2866篇
冶金工业   1397篇
原子能技术   383篇
自动化技术   9410篇
  2024年   135篇
  2023年   440篇
  2022年   831篇
  2021年   1075篇
  2020年   1196篇
  2019年   997篇
  2018年   916篇
  2017年   1490篇
  2016年   1442篇
  2015年   1553篇
  2014年   2524篇
  2013年   2664篇
  2012年   3164篇
  2011年   3543篇
  2010年   2552篇
  2009年   2659篇
  2008年   2605篇
  2007年   3277篇
  2006年   2767篇
  2005年   2553篇
  2004年   1967篇
  2003年   1762篇
  2002年   1446篇
  2001年   1276篇
  2000年   1129篇
  1999年   878篇
  1998年   587篇
  1997年   606篇
  1996年   472篇
  1995年   387篇
  1994年   343篇
  1993年   251篇
  1992年   208篇
  1991年   181篇
  1990年   134篇
  1989年   104篇
  1988年   79篇
  1987年   58篇
  1986年   38篇
  1985年   25篇
  1984年   43篇
  1983年   42篇
  1982年   43篇
  1981年   26篇
  1980年   18篇
  1979年   12篇
  1978年   11篇
  1977年   13篇
  1959年   9篇
  1956年   6篇
排序方式: 共有10000条查询结果,搜索用时 30 毫秒
101.
Many everyday activities depend on the capacity to organize and smoothly execute motor sequences. The authors tested the hypothesis that a sequencing deficit is associated with schizophrenia. They used a new method to distinguish between lower and higher order mechanisms for the impairment. The 1st task involved triggered sequences in which sensory information from 1 movement was the cue for initiation of the following movement. Results showed that the motor sequences were performed as fluently in patients as in controls. The 2nd and 3rd tasks involved sequences in which the entire movement sequence could be preplanned. Patients executed the sequences less fluently than controls but only under the condition where action sequences were required. Furthermore, the patients' fluency deficit increased with sequence complexity. The high discrimination power of Task 3 gave the authors a means to control for a potential psychometric confound involving differential discriminating power and to argue in favor of a specific higher order motor fluency deficit in patients with schizophrenia. It is suggested that basic lower order mechanisms that integrate sensory information with outgoing motor commands are preserved in schizophrenia, whereas higher order integrative mechanisms that are required for the smooth coordination of motor sequences are impaired. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
102.
Windows 95/98环境下PC机并行打印端口控制步进电机的研究   总被引:1,自引:0,他引:1  
介绍了在Windows95/98环境下利用IBM-PC机打印端口控制步进电机运动的实现方法,并给出了关键程序的实现代码。  相似文献   
103.
In this article, linear programming and fuzzy optimization models are developed for planning and management of available land-water-crop system of Mahanadi-Kathajodi delta in eastern India. The models are used to optimize the economic return, production and labour utilization, and to search the related cropping patterns and intensities with specified land, water, fertilizer and labour availability, and water use pattern constraints. Due to extreme backwardness of the study area, it has been decided to keep all the three objectives of the linear programming models at the same priority level to obtain the compromised solution in a fuzzy environment that incorporates the imprecision in fuzzy goals and fuzzy constraints. These non-structural models facilitate the conjunctive use of available surface water and groundwater resources. A comparative evaluation along with the benefit-cost ratios of the existing and proposed farming systems is also presented.  相似文献   
104.
We consider systems which are globally completely observable and output-to-state stable. The former property guarantees the existence of coordinates such that the dynamics can be expressed in observability form. The latter property guarantees the existence of a state norm observer and therefore the possibility of bounding any continuous state functions. Both properties allow to conceptually build an observer from an approximation of an exponentially attractive invariant manifold in the space of the system state and an output driven dynamic extension. The proposed observer provides convergence to zero of the estimation error within the domain of definition of the solutions. The work of A. Astolfi is partly supported by the Leverhulme Trust.  相似文献   
105.
This paper presents a critical evaluation of existing FMS architectures and the academic and industrial design and development strategies used during their formulation. The paper seeks to address the need for, and value of, existing architectures within the industrial arena. More importantly however, this paper puts forward a new two-tier distributed control architecture for FMS based upon new (real-time) networkable DSP servo control methodologies developed by one of the authors for Softronics in Australia. The ramifications of these methodologies are substantial, not only in terms of FMS control, but in the overall simplification of such systems and the development of flexible fixturing devices over the coming decade. This paper also postulates on how new FMS architectures can be developed from such technologies and details why such architectures could be more appropriate to industry needs than those that are currently in existence.  相似文献   
106.
空调器用盘式电机的计算机模拟   总被引:1,自引:0,他引:1  
郭庆吉  刘晓胜 《微电机》1993,26(4):9-12
介绍线绕盘式永磁直流电流电动机的结构特点,设计原则和有关的主要设计公式,并进行电机的计算机模拟。模拟运行结果与样机实测数据基本相符。  相似文献   
107.
采用电子表格软件EXCEL5.0可以方便地解决许多选煤生产中的线性规划问题。本文通过选煤过程线性规划实例介绍EXCEL5.0在此领域的应用方法。  相似文献   
108.
本文介绍了可编程控制器(PLC)在包装机上的应用.介绍了系统的硬件设计与软件开发.  相似文献   
109.
海洋机器人用水下电机的深水密封研究   总被引:5,自引:0,他引:5  
本文研究了海洋机器人用水下电机各个部分的密封方法,同时介绍了一个先进的动密封装置以及检验密封性能的水压试验方法.经测试及实际使用表明该密封方法和动密封装置完全满足水下机器人在深水中运行的密封要求  相似文献   
110.
一个矢量形式的双圆弧插值算法   总被引:3,自引:1,他引:2  
本文在分析数控插补最常用的双圆弧插值算法特点的基础上,将以局部坐标系中的三角运算为核心的传统双圆弧插值算法,改造成为以整体坐标系中的线性运算为核心的矢量形式的双圆弧插值算法,从而减少了计算的复杂性和程序的复杂性,提高了效率和可靠性。  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