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   37948篇
  免费   5488篇
  国内免费   2294篇
电工技术   7004篇
综合类   3762篇
化学工业   597篇
金属工艺   340篇
机械仪表   1867篇
建筑科学   840篇
矿业工程   522篇
能源动力   887篇
轻工业   764篇
水利工程   664篇
石油天然气   359篇
武器工业   353篇
无线电   8053篇
一般工业技术   1321篇
冶金工业   284篇
原子能技术   131篇
自动化技术   17982篇
  2025年   385篇
  2024年   1021篇
  2023年   972篇
  2022年   1169篇
  2021年   1333篇
  2020年   1476篇
  2019年   1250篇
  2018年   1084篇
  2017年   1388篇
  2016年   1598篇
  2015年   1726篇
  2014年   2643篇
  2013年   2448篇
  2012年   2734篇
  2011年   2581篇
  2010年   2144篇
  2009年   2161篇
  2008年   2425篇
  2007年   2663篇
  2006年   2110篇
  2005年   2133篇
  2004年   1787篇
  2003年   1471篇
  2002年   1118篇
  2001年   912篇
  2000年   629篇
  1999年   474篇
  1998年   373篇
  1997年   295篇
  1996年   284篇
  1995年   280篇
  1994年   188篇
  1993年   107篇
  1992年   100篇
  1991年   60篇
  1990年   39篇
  1989年   26篇
  1988年   39篇
  1987年   14篇
  1986年   11篇
  1985年   14篇
  1984年   10篇
  1983年   9篇
  1982年   9篇
  1981年   7篇
  1980年   12篇
  1979年   6篇
  1978年   5篇
  1977年   3篇
  1976年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Currently there are design barriers inhibiting the implementation of high-precision digital signal processing (DSP) objects with field programmable logic (FPL) devices. This paper explores overcoming these barriers by fusing together the popular distributed arithmetic (DA) method with the residue number system (RNS) for use in FPL-centric designs. The new design paradigm is studied in the context of a high-performance filter bank and a discrete wavelet transform (DWT). The proposed design paradigm is facilitated by a new RNS accumulator structure based on a carry save adder (CSA). The reported methodology also introduces a polyphase filter structure that results in a reduced look-up table (LUT) budget. The 2C-DA and RNS-DA are compared, in the context of a FPL implementation strategy, using a discrete wavelet transform (DWT) filter bank as a common design theme. The results show that the RNS-DA, compared to a traditional 2C-DA design, enjoys a performance advantage that increases with precision (wordlength).  相似文献   
2.
In this paper, we propose a new approach for signal detection in wireless digital communications based on the neural network with transient chaos and time-varying gain (NNTCTG), and give a concrete model of the signal detector after appropriate transformations and mappings. It is well known that the problem of the maximum likelihood signal detection can be described as a complex optimization problem that has so many local optima that conventional Hopfield-type neural networks fail to solve. By refraining from the serious local optima problem of Hopfield-type neural networks, the NNTCTG makes use of the time-varying parameters of the recurrent neural network to control the evolving behavior of the network so that the network undergoes the transition from chaotic behavior to gradient convergence. It has richer and more flexible dynamics rather than conventional neural networks only with point attractors, so that it can be expected to have much ability to search for globally optimal or near-optimal solutions. After going through a transiently inverse-bifurcation process, the NNTCTG can approach the global optimum or the neighborhood of global optimum of our problem. Simulation experiments have been performed to show the effectiveness and validation of the proposed neural network based method for the signal detection in digital communications.  相似文献   
3.
The requirements on an object-oriented DBMS for management of information in a large, complex enterprise are presented. These requirements aid in the achievement of an environment characterized by data sharing, open architectures, application and data portability, and assurance of data integrity. They were defined from the point of view of a user of the DBMS; therefore they describe the expected functionality of the DBMS and do not specify the method of implementation to achieve this functionality. They encompass requirements on the data model, query and data manipulation languages, the system architecure, interfaces to the system, change management, and transaction management.  相似文献   
4.
When ground-fault problems occur on a cable line, immediate fault location and restoration are required. Therefore, various new methods to locate the fault point instantaneously have been investigated to replace such conventional methods as the Murray loop method and the pulse radar method [1]. These methods require a long time to locate the fault point. One possible fault location method is to sense the temperature rise following a ground fault using a fiber optic distributed temperature sensor. Application of this method was found feasible through sensing the temperature rise at a ground-fault test using a thermocouple as a temperature sensor with test cables [4]. A power/optical composite cable was prepared experimentally and after verifying its thermal mechanical performance, the temperature rise at an incidence of a fault was determined and the anticipated performance was demonstrated in a ground-fault test. This article describes the outline of the test.  相似文献   
5.
New small‐scale dispersed generation systems, such as fuel cells and micro gas turbines, have made remarkable advances lately and they will be applied practically in the near future. Although a large number of researches on the introduction of small‐scale dispersed generation systems have been carried out, only a small number of small‐scale dispersed generation systems are considered in these researches. Therefore, little is known about problems to be solved when a large number of small‐scale dispersed generation systems are introduced into electric power systems. This paper deals with a super‐distributed energy system that consists of a great number of dispersed generation systems such as fuel cells, micro gas turbines, and so on. The behavior of a customer with a dispersed generation system is simulated as the Ising model in statistical mechanics. The necessity of a distribution network in super‐distributed energy systems is discussed based on the Ising model. The feasibility of decentralized autonomous control using vicinity information is also investigated on the basis of stability analysis of the Hopfield neural network model. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(1): 43–55, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10368  相似文献   
6.
As the use of smartphones become popular,people heavily depend on smartphone applications to deal with their social activities.For this reason,traditional message texting between mobile applications does not fulfill the versatile requirements of social networking.Many mobile applications use multimodality to deliver multimedia messages including sticker,voice and photo message,video call,and snap movie to enhance the communicative capability.However,without face-to-face interaction,people may fail to detect the other side’s non-verbal social behavior such as fine-grain facial expressions,body movements,or hand gesture.During social interaction,non-verbal behavior conveys information about the involved individuals and help the speakers express their social emotion in an implicit way.It is so important for real-world face-to-face interaction but is often blocked on the mobile telephony.To cope with this problem,we propose an afective computing model to assist the representation of social emotion and then help the progress of social interaction on the mobile telephony.In this model,for the purpose of real-time afective analysis,we delegate the computing loading to the cloud side service and enhance the system’s scalability and availability.The result of this experiment approves the feasibility of our system design for the applications of social intelligent.Also,the system provides a research framework of the social intelligent system on the mobile telephony.  相似文献   
7.
由于创建数据库操作不能自动回滚,所以无法将动态创建数据库的操作包含在事务内处理。本文介绍了通过程序的异常处理和SQL Server的事务处理机制创建数据库不可分割地完成其他一些操作,从而达到并发控制的一种可行方法。  相似文献   
8.
为满足非接触化、小型化、集成化、数字化、智能化等现代检测技术的发展要求,从成本、工作原理、灵敏度等方面综合考虑,现采用以光电定位模块为核心的光电定位技术,以无线传感器网络作为数据传输与管理的技术手段,构建了无线光电定位网络,并进行了实验分析.可实现多点实时监测、异地显示测量数据、数据网络化管理等特殊需求;涵盖了多学科领...  相似文献   
9.
介绍了InTouch在吉林建龙钢铁公司热风炉工程中的应用,论述了热风炉系统结构和信息通讯方式.应用表明设计合理,达到了实时监控的目的.  相似文献   
10.
基于攻击前提和后果关联的技术有多种,在此基础上,研究并实现了一种面向分布式的多源实时报警收集及关联分析的框架。初步实验证明,该框架在复杂的网络环境下能够有效地减少和分析报警事件,帮助管理员从大量数据中找到重要信息。  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