全文获取类型
收费全文 | 184913篇 |
免费 | 17342篇 |
国内免费 | 13215篇 |
专业分类
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 |
出版年
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.
D.E. Kvasov D. Menniti A. Pinnarelli Y.D. Sergeyev N. Sorrentino 《Electric Power Systems Research》2008
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.
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.
J. R. Prez-Correa F. R. Sepúlveda M. A. Duarte 《International Journal of Adaptive Control and Signal Processing》1995,9(2):183-197
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.
Manabu Ishitobi Takeshi Myoi Koji Soshin Eiji Hiraki Mutsuo Nakaoka 《Electrical Engineering in Japan》2005,153(3):79-87
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