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   48799篇
  免费   6399篇
  国内免费   2967篇
电工技术   10773篇
技术理论   3篇
综合类   4420篇
化学工业   1751篇
金属工艺   794篇
机械仪表   3257篇
建筑科学   800篇
矿业工程   748篇
能源动力   3207篇
轻工业   943篇
水利工程   787篇
石油天然气   1501篇
武器工业   769篇
无线电   11627篇
一般工业技术   2850篇
冶金工业   765篇
原子能技术   331篇
自动化技术   12839篇
  2024年   288篇
  2023年   820篇
  2022年   1418篇
  2021年   1667篇
  2020年   1715篇
  2019年   1402篇
  2018年   1253篇
  2017年   1829篇
  2016年   1950篇
  2015年   2273篇
  2014年   3381篇
  2013年   2999篇
  2012年   3973篇
  2011年   4224篇
  2010年   3077篇
  2009年   3036篇
  2008年   3102篇
  2007年   3580篇
  2006年   2948篇
  2005年   2612篇
  2004年   2051篇
  2003年   1589篇
  2002年   1243篇
  2001年   1055篇
  2000年   913篇
  1999年   693篇
  1998年   513篇
  1997年   483篇
  1996年   392篇
  1995年   346篇
  1994年   286篇
  1993年   244篇
  1992年   172篇
  1991年   130篇
  1990年   101篇
  1989年   76篇
  1988年   63篇
  1987年   37篇
  1986年   22篇
  1985年   40篇
  1984年   27篇
  1983年   27篇
  1982年   19篇
  1981年   17篇
  1980年   22篇
  1979年   8篇
  1978年   7篇
  1977年   9篇
  1963年   4篇
  1959年   5篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
智能电源系统在信号领域中的应用   总被引:1,自引:0,他引:1  
随着轨道交通的发展,信号设备要求具备智能化、模块化、自动化、网络化的智能电源系统。针对信号系统的发展对智能电源系统的要求,阐述了智能电源系统在智能化、模块化、自动化三方面的应用。介绍了目前智能电源系统所采用各种不同的技术方案,并论述了方案的优缺点,总结了目前存在的问题和发展方向。  相似文献   
92.
The purpose of this paper is to stimulate interest within the civil engineering research community for developing the next generation of applied artificial neural networks. In particular, it identifies what the next generation of these devices needs to achieve, and provides direction in terms of how their development may proceed. An analysis of the current situation indicates that progress in the development of artificial neural network applications has largely stagnated. Suggestions are made for advancing the field to the next level of sophistication and application, using genetic algorithms and related techniques. It is shown that this approach will require the design of some very sophisticated genetic coding mechanisms in order to develop the required higher-order network structures, and will utilize development mechanisms observed in nature such as growth, self-organization, and multi-stage objective functions. The capabilities of such an approach and the way in which they can be achieved are explored with reference to the problems of: (a) determining truck attributes from the strain envelopes they induce in structural members when crossing a bridge, and; (b) developing a decision support system for dynamic control of industrialized manufacturing of houses.  相似文献   
93.
This paper presents an approach to automatic course generation and student modeling. The method has been developed during the European funded projects Diogene and Intraserv, focused on the construction of an adaptive e-learning platform. The aim of the platform is the automatic generation and personalization of courses, taking into account pedagogical knowledge on the didactic domain as well as statistic information on both the student’s knowledge degree and learning preferences. Pedagogical information is described by means of an innovative methodology suitable for effective and efficient course generation and personalization. Moreover, statistic information can be collected and exploited by the system in order to better describe the student’s preferences and learning performances. Learning material is chosen by the system matching the student’s learning preferences with the learning material type, following a pedagogical approach suggested by Felder and Silverman. The paper discusses how automatic learning material personalization makes it possible to facilitate distance learning access to both able-bodied and disabled people. Results from the Diogene and Intraserv evaluation are reported and discussed.  相似文献   
94.
We present a novel mobile code management environment,currently under design and development. Our design employs anopen architecture, suitable for ``plug-and-play' with COTS andother groups' tools. While we have studied new algorithms, costand objective functions, and other fundamental issues, the maincontribution of this experimental research work is in the environmentitself. It should be noted that networked platforms, such asthe World Wide Web, are inherently not suitable for traditional,predictable real-time applications. Thus, real-time concernsnecessarily need to be blended with others concerns, and thetarget applications, making use of our environment, will toobe a blend of partially hard real-time and partially (or mostly)soft-real- time ones. The prototype environment will thereforesupport performance-based analysis and management focusing notonly on predictability but also on compilation, efficiency, safetyand other tradeoffs. We have selected the Java language and itsbytecode format as a representation for mobile code as well asa language for our implementation.  相似文献   
95.
Recently, High Performance Computing (HPC) platforms have been employed to realize many computationally demanding applications in signal and image processing. These applications require real-time performance constraints to be met. These constraints include latency as well as throughput. In order to meet these performance requirements, efficient parallel algorithms are needed. These algorithms must be engineered to exploit the computational characteristics of such applications. In this paper we present a methodology for mapping a class of adaptive signal processing applications onto HPC platforms such that the throughput performance is optimized. We first define a new task model using the salient computational characteristics of a class of adaptive signal processing applications. Based on this task model, we propose a new execution model. In the earlier linear pipelined execution model, the task mapping choices were restricted. The new model permits flexible task mapping choices, leading to improved throughput performance compared with the previous model. Using the new model, a three-step task mapping methodology is developed. It consists of (1) a data remapping step, (2) a coarse resource allocation step, and (3) a fine performance tuning step. The methodology is demonstrated by designing parallel algorithms for modern radar and sonar signal processing applications. These are implemented on IBM SP2 and Cray T3E, state-of-the-art HPC platforms, to show the effectiveness of our approach. Experimental results show significant performance improvement over those obtained by previous approaches. Our code is written using C and the Message Passing Interface (MPI). Thus, it is portable across various HPC platforms. Received April 8, 1998; revised February 2, 1999.  相似文献   
96.
一种基于DSP的雷达信号实时处理系统   总被引:1,自引:0,他引:1  
介绍了在特定环境下使用的一种雷达信号实时处理系统的结构,工作原理与工作流程。  相似文献   
97.
∶为高效开发老挝电源BOT项目,文章对老挝电源BOT项目的开发现状及实施步骤进行简介,并针对老挝电源BOT项目存在的风险,进行了策略性的讨论和研究,供同行们参考。  相似文献   
98.
99.
一种新型ICA算法在RFID系统中的应用   总被引:1,自引:0,他引:1  
针对无线射频识别系统在通信过程中的防碰撞问题,从信号处理的角度,提出一种基于盲源信号并行分离技术的防碰撞处理算法,其中包括信号白化技术,以及一种改进的独立元分析(ICA)信号并行分离方法.功能仿真结果证明,该算法的吞吐率最高达到69%,与吞吐率只有18%的传统Aloha算法相比,该算法能提高防碰撞能力.  相似文献   
100.
森林保险市场的信号甄别和激励机制   总被引:5,自引:0,他引:5  
基于森林保险市场存在的两种不确定因素,从减少道德风险和抑制逆向选择两方面出发,同时引入了免赔额和共保率,并对投保林主和森林进行综合风险分类,构建了一个信号甄别和激励模型,导出了一种符合森林保险市场发展需要的费率与共保率厘定体系.该方法打破了传统森林保险费率统一的定价模式.  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