全文获取类型
收费全文 | 25596篇 |
免费 | 2416篇 |
国内免费 | 1468篇 |
专业分类
电工技术 | 9868篇 |
技术理论 | 1篇 |
综合类 | 2416篇 |
化学工业 | 1429篇 |
金属工艺 | 1015篇 |
机械仪表 | 1852篇 |
建筑科学 | 1068篇 |
矿业工程 | 989篇 |
能源动力 | 1422篇 |
轻工业 | 828篇 |
水利工程 | 347篇 |
石油天然气 | 870篇 |
武器工业 | 375篇 |
无线电 | 1795篇 |
一般工业技术 | 1519篇 |
冶金工业 | 1350篇 |
原子能技术 | 169篇 |
自动化技术 | 2167篇 |
出版年
2024年 | 156篇 |
2023年 | 409篇 |
2022年 | 706篇 |
2021年 | 776篇 |
2020年 | 875篇 |
2019年 | 689篇 |
2018年 | 638篇 |
2017年 | 816篇 |
2016年 | 803篇 |
2015年 | 911篇 |
2014年 | 1753篇 |
2013年 | 1386篇 |
2012年 | 1999篇 |
2011年 | 1964篇 |
2010年 | 1279篇 |
2009年 | 1385篇 |
2008年 | 1366篇 |
2007年 | 1701篇 |
2006年 | 1588篇 |
2005年 | 1369篇 |
2004年 | 1202篇 |
2003年 | 1156篇 |
2002年 | 844篇 |
2001年 | 766篇 |
2000年 | 598篇 |
1999年 | 494篇 |
1998年 | 351篇 |
1997年 | 276篇 |
1996年 | 250篇 |
1995年 | 203篇 |
1994年 | 170篇 |
1993年 | 103篇 |
1992年 | 108篇 |
1991年 | 54篇 |
1990年 | 48篇 |
1989年 | 53篇 |
1988年 | 43篇 |
1987年 | 32篇 |
1986年 | 17篇 |
1985年 | 10篇 |
1984年 | 31篇 |
1983年 | 41篇 |
1982年 | 22篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1957年 | 2篇 |
1955年 | 3篇 |
1954年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
The transmission mode of holographic polymer‐dispersed liquid crystals (HPDLCs) was developed an under electric field. It is reported that orientation of LC molecules under an electric field induces orientation of oligomer molecules giving rise to low off‐state diffraction and small grating shrinkage. Copyright © 2005 Society of Chemical Industry 相似文献
2.
This paper describes an effective analysis of magnetic shielding based on homogenization. The analyses become time‐consuming if the problems include the magnetic substances having fine structure. The homogenization of the structure makes it possible to analyze effectively the magnetic fields. The authors introduce a method to estimate the effective permeability of the homogenized substance. This method can be applied to any periodic structure made of magnetic substance. The magnetic shielding effects by the structures against direct‐current (DC) fields generated by electric railways are analyzed by using the present method. As a result, it is found that the overhead way and the protective fence near the railway work as a magnetic shield, whose effects can be improved by appropriate arrangement of those constructions. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(4): 7–15, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20310 相似文献
3.
用于重离子核反应实验测量的纵向电场气体电离室 总被引:1,自引:0,他引:1
本文报道了一种新型的大动态范围,多叠层探测器系统组件之一的纵向电场气体电离室的构造,性能和在中能得离子核反应实验中的应用。 相似文献
4.
This paper presents an electromechanical wheel suspension, where the upper arm of the suspension has been provided with an electric levelling and a damper actuator, both are allowed to work in a fully active mode. A control structure for the proposed suspension is described. The complex design task involving the control of the electric damper and its machine parameters is tackled by genetic optimisation. During this process, these parameters are optimised to keep the power dissipation of the electric damper as low as possible, while maintaining acceptable comfort and road-holding capabilities. The results of the evaluations carried out demonstrate that the proposed suspension can easily adopt its control parameters to obtain a better compromise of performance than that offered by passive suspensions. If the vehicle is to maintain acceptable performance during severe driving conditions, the damper has to be unrealistically large. However, if the electric damper is combined with a hydraulic damper, the size of the electric damper is significantly reduced. In addition, the design of the electric damper with the suggested control structure, including how it regenerates energy, is discussed. 相似文献
5.
分析实现永州电力通信交换网集中操作和维护的必要性,介绍了实现程控交换机远程操作和维护的两种方式,总结在实践过程中所得到的经验和教训。 相似文献
6.
7.
8.
A novel current source inverter system interconnected to the single‐phase grid is proposed. It has the same construction as the conventional three‐phase current source inverter that is interconnected to the single‐phase three‐wire distribution system. Though the proposed circuit has no output transformer, it can be equivalently performed as the single‐phase double cascade inverter by diverting the pole transformer in the utility system. By controlling the appropriate scheme, the output currents can be obtained as the five‐level waveforms and their distortions can be decreased sufficiently. It is applied to the interactive electric energy storage system with batteries and the basic discharging characteristics are discussed experimentally. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 50–61, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10380 相似文献
9.
Xiaoxiang Hu Changhua Hu Zhaoqiang Wang Huijun Gao 《International journal of systems science》2014,45(8):1740-1756
By utilising Takagi–Sugeno (T–S) fuzzy set approach, this paper addresses the robust H∞ dynamic output feedback control for the non-linear longitudinal model of flexible air-breathing hypersonic vehicles (FAHVs). The flight control of FAHVs is highly challenging due to the unique dynamic characteristics, and the intricate couplings between the engine and fight dynamics and external disturbance. Because of the dynamics’ enormous complexity, currently, only the longitudinal dynamics models of FAHVs have been used for controller design. In this work, T–S fuzzy modelling technique is utilised to approach the non-linear dynamics of FAHVs, then a fuzzy model is developed for the output tracking problem of FAHVs. The fuzzy model contains parameter uncertainties and disturbance, which can approach the non-linear dynamics of FAHVs more exactly. The flexible models of FAHVs are difficult to measure because of the complex dynamics and the strong couplings, thus a full-order dynamic output feedback controller is designed for the fuzzy model. A robust H∞ controller is designed for the obtained closed-loop system. By utilising the Lyapunov functional approach, sufficient solvability conditions for such controllers are established in terms of linear matrix inequalities. Finally, the effectiveness of the proposed T–S fuzzy dynamic output feedback control method is demonstrated by numerical simulations. 相似文献
10.
大压差减温减压是能的严重贬值。根据公司供热现状,分析了热电联产的可行性,利用蒸汽余压发电后,再供生产系统各热用户,这样既节约了能源又缓解了集团公司用电紧张的局面,而且有相当可观的经济效益。 相似文献