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   184913篇
  免费   17342篇
  国内免费   13215篇
电工技术   31439篇
技术理论   7篇
综合类   17840篇
化学工业   9281篇
金属工艺   6737篇
机械仪表   16766篇
建筑科学   15263篇
矿业工程   7134篇
能源动力   4871篇
轻工业   4702篇
水利工程   5607篇
石油天然气   5737篇
武器工业   2897篇
无线电   16588篇
一般工业技术   8933篇
冶金工业   7954篇
原子能技术   1214篇
自动化技术   52500篇
  2024年   837篇
  2023年   2291篇
  2022年   3625篇
  2021年   4429篇
  2020年   5357篇
  2019年   4274篇
  2018年   3830篇
  2017年   5448篇
  2016年   6034篇
  2015年   6736篇
  2014年   12419篇
  2013年   10849篇
  2012年   13600篇
  2011年   14598篇
  2010年   11051篇
  2009年   11322篇
  2008年   11329篇
  2007年   13756篇
  2006年   12315篇
  2005年   10702篇
  2004年   8859篇
  2003年   7813篇
  2002年   6207篇
  2001年   5170篇
  2000年   4456篇
  1999年   3578篇
  1998年   2748篇
  1997年   2414篇
  1996年   1929篇
  1995年   1567篇
  1994年   1322篇
  1993年   966篇
  1992年   771篇
  1991年   575篇
  1990年   445篇
  1989年   381篇
  1988年   273篇
  1987年   161篇
  1986年   115篇
  1985年   110篇
  1984年   157篇
  1983年   122篇
  1982年   117篇
  1981年   81篇
  1980年   57篇
  1979年   65篇
  1978年   49篇
  1977年   49篇
  1964年   14篇
  1959年   14篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
现场总线控制系统浅谈   总被引:1,自引:0,他引:1  
简述了现场总线控制系统的结构及其显优点。现场总线控制系统的结构包括:主控器、总线接口、电源、输入/输出接点、总线电揽和终端电阻。另外对其显优点做了逐一介绍。现场总线控制系统可在工业自动化控制系统中推广应用。  相似文献   
72.
A new approach to study ergodicity of filtering processes is presented. It is based on the vanishing discount approach to discounted functional of filtering process. We show that limit superior of the Cesaro averages of the functionals is the same for all initial conditions from which the uniqueness of invariant measures of filtering processes follows. The approach is based on certain assumption for which we provide a sufficient condition using concavity arguments. In addition we show the existence of solutions to the Poisson equation corresponding to filtering process with concave functional. The assumptions are then extended to the controlled case and using similar concave arguments we obtain the existence of solutions to the Bellman equation corresponding to partially observed average cost per unit time problem.  相似文献   
73.
设计一条钢筋网自动化焊接生产线,包括经料送料平台、纬料自动分料及上料机构、多点电阻点焊机、接料平台、卸料机械手。从上料到出料依靠电机、汽缸之间的协调工作来实现。并由单片机和PLC实现控制功能,上位机用MCGS组态软件在整个过程监视现场,采集工作状态及参数,起到监控作用。  相似文献   
74.
In this paper, the problem of global tuning of fuzzy power-system stabilizers (FPSSs) present in a multi-machine power system in order to damp the power system oscillations is considered. In particular, it is formulated as a problem of global minimization of a multiextremal black-box function over a multidimensional hyperinterval. A global optimization technique, recently proposed, is used for solving the stated problem: the search hyperinterval is partitioned into smaller hyperintervals and the objective function is evaluated only at two vertices corresponding to the main diagonal of the generated hyperintervals, thus avoiding unnecessary ponderous simulations. Then, the performances of this technique are numerically compared with ones of a genetic algorithm (GA).  相似文献   
75.
连铸钢液温度变化规律及控制的研究   总被引:2,自引:0,他引:2  
鲁开嶷 《冶金能源》1993,12(3):16-21
  相似文献   
76.
In arc welding processes, because of the complexity and nonlinearity of heat transfer phenomena, it is often difficult to design an effective control system based upon an exact mathematical model. In this paper, a self-organizing fuzzy control method is proposed to obtain a uniform weld quality by regulation of the surface temperature at a desired level. The proposed control system is designed to comprise a combined structure of the fuzzy SOC with conventional PD control for improving the system's stability. The control experiments show that the proposed controller guarantees a uniform weld quality for various welding conditions.  相似文献   
77.
This paper presents experimental results obtained in temperature adaptive control of a heating vessel. A non-linear model of the process showed that the feed flow rate causes severe variations in time constant and process gain. An extended horizon self-tuning controller and two different model reference adaptive controllers were tested. The influence of design parameters on control performance for each algorithm was assessed. The control system was disturbed with load and setpoint changes.  相似文献   
78.
79.
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   
80.
This paper presents a single lossless inductive snubber‐assisted ZCS‐PFM series resonant DC‐DC power converter with a high‐frequency high‐voltage transformer link for industrial‐use high‐power magnetron drive. The current flowing through the active power switches rises gradually at a turned‐on transient state with the aid of a single lossless snubber inductor, and ZCS turn‐on commutation based on overlapping current can be achieved via the wide range pulse frequency modulation control scheme. The high‐frequency high‐voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high‐frequency high‐voltage transformer and the magnetizing inductance of the high‐frequency high‐voltage transformer. As a result, this high‐voltage power converter circuit for the magnetron can achieve a complete zero current soft switching under the condition of broad width gate voltage signals. Furthermore, this high‐voltage DC‐DC power converter circuit can regulate the output power from zero to full over audible frequency range via the two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 79–87, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20126  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