全文获取类型
收费全文 | 333172篇 |
免费 | 24028篇 |
国内免费 | 12556篇 |
专业分类
电工技术 | 17925篇 |
技术理论 | 56篇 |
综合类 | 19692篇 |
化学工业 | 56595篇 |
金属工艺 | 18554篇 |
机械仪表 | 21178篇 |
建筑科学 | 25730篇 |
矿业工程 | 10964篇 |
能源动力 | 9764篇 |
轻工业 | 18636篇 |
水利工程 | 5255篇 |
石油天然气 | 22987篇 |
武器工业 | 2601篇 |
无线电 | 36646篇 |
一般工业技术 | 39821篇 |
冶金工业 | 18402篇 |
原子能技术 | 3215篇 |
自动化技术 | 41735篇 |
出版年
2024年 | 1290篇 |
2023年 | 5213篇 |
2022年 | 8878篇 |
2021年 | 12551篇 |
2020年 | 9830篇 |
2019年 | 8010篇 |
2018年 | 9207篇 |
2017年 | 10387篇 |
2016年 | 9281篇 |
2015年 | 12231篇 |
2014年 | 15878篇 |
2013年 | 19191篇 |
2012年 | 20172篇 |
2011年 | 22455篇 |
2010年 | 19213篇 |
2009年 | 18335篇 |
2008年 | 17985篇 |
2007年 | 17404篇 |
2006年 | 18284篇 |
2005年 | 16137篇 |
2004年 | 10350篇 |
2003年 | 9131篇 |
2002年 | 8135篇 |
2001年 | 7477篇 |
2000年 | 8006篇 |
1999年 | 9655篇 |
1998年 | 8159篇 |
1997年 | 6769篇 |
1996年 | 6365篇 |
1995年 | 5340篇 |
1994年 | 4380篇 |
1993年 | 3090篇 |
1992年 | 2493篇 |
1991年 | 1962篇 |
1990年 | 1505篇 |
1989年 | 1233篇 |
1988年 | 1020篇 |
1987年 | 681篇 |
1986年 | 535篇 |
1985年 | 342篇 |
1984年 | 243篇 |
1983年 | 204篇 |
1982年 | 196篇 |
1981年 | 129篇 |
1980年 | 130篇 |
1979年 | 67篇 |
1978年 | 33篇 |
1977年 | 38篇 |
1976年 | 55篇 |
1975年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
921.
922.
Xiao Sun Chow M.H.L. Leung F.H.F. Dehong Xu Yousheng Wang Yim-Shu Lee 《Power Electronics, IEEE Transactions on》2002,17(3):305-313
An analogue neural-network controller for UPS inverter applications is presented. The proposed neural-network controller is trained off-line using patterns obtained from a simulated controller, which had an idealized load-current-reference. Simulation results show that the proposed neural-network controller can achieve low total harmonic distortion under nonlinear loading condition and good dynamic responses under transient loading condition. To verify the performance of the proposed NN controller, a hardware inverter with an analogue neural network (NN) controller (using mainly operational amplifiers and resistors) is built. Additionally, for comparison purposes, a PI controller with optimized parameters is built. Experimental results confirm the simulation results and show the superior performance of the NN controller especially under rectifier-type loading condition. Implementing the analogue neural-network controller using programmable integrated circuits is also discussed 相似文献
923.
Jiabin Wang Weiya Wang Jewell G.W. Howe D. 《Industrial Electronics, IEEE Transactions on》2002,49(3):640-648
This paper describes the design, analysis and characterization of a linear permanent magnet generator and capacitive energy storage system for generating electrical power from a single stroke of a salient-pole armature. It is suitable for applications that require relatively low levels of electrical power, such as remote electronic locks. An electromagnetic analysis of the generator is described, and a design optimization methodology for the system is presented. Finally, the performance of a prototype is validated against measurements 相似文献
924.
925.
Tetrahedrally close-packed structures with juxtaposed pentagonal antiprisms, such as the μ, C14 Laves and the newly found C phases, were studied by means of HREM and SAD. It was found that each bright spot in the structural image corresponds to an antiprism. Differently oriented domains of these phases intergrow frequently with a fairly good match at the interphase boundary. All diffraction patterns of these phases show a fivefold distribution of spot-pairs, and it is shown that this fivefold symmetry comes from the pentagons and spot-pairs from two pentagonal prisms superposed in antisymmetrical positions. 相似文献
926.
Failure analysis and a study of the wear mechanism were performed on a heavily loaded carburized gear with some unusual features. The analysis showed that the different failure forms on the tooth surface of the gear were dependent on the sub-surface shearing stress, the lubrication conditions and the surface roughness. Delaminations formed on the addendum surface were the main reason for the gear failure. A suggestion for improvement has been tried, and a desirable result has been obtained. 相似文献
927.
本文借助图论的理论,通过识别回路和不包含回路的由起始状态到终止状态的路径的方法,提出一种构造给定有穷自动机对应的正则表达式的新算法,并给出具体实例。 相似文献
928.
Sheng-Guo Wang Author Vitae 《Automatica》2003,39(3):525-532
This paper presents a general analysis of robust pole clustering in a good ride quality region (GRQR) of aircraft for matrices with structured uncertainties. This region is an intersection of a ring and a horizontal strip, located in the left half-plane, which is a specific non-Ω-transformable region providing good ride quality of aircraft. The paper applies the Rayleigh principle along the norm theory to analyze robust pole clustering within this region since the generalized Lyapunov theory is not valid for non-Ω-transformable regions. Concerned uncertainties are structured/parametric uncertainties, including interval matrices. The results are useful for robust control analysis and design, especially, of robust good ride quality of aircraft, shuttles, vehicles and space station, as well as some industrial systems. An example of the F-16 dynamics for which GRQR is suitable is included to illustrate the results. 相似文献
929.
A pilot-scale fluidised pellet bed (FPB) bioreactor, which combines chemical coagulation, biological degradation, particle pelletisation and separation in one unit, was applied for onsite wastewater treatment and reuse. As a result of rational use of inorganic coagulant and organic polymer and moderate mechanical agitation, spherical particles were generated in the upflow column and a well-fluidised bed was formed. With a continuous supply of dissolved oxygen through a recycling loop, an aerobic condition was kept in the bottom section of the FPB column. Under such conditions the pellets in the FPB column showed the following characteristics: (1) compact structure and high density; (2) rich in microorganisms; and (3) high MLSS and MLVSS concentrations. Therefore, the FPB bioreactor achieved more than 90% removal of SS, COD, BOD and TP from raw domestic wastewater within a total hydraulic retention time (HRT) of only about 30 minutes. It also showed nitrification and denitrification ability and the TN removal could be about 50% as the recycling ratio was increased to 1:1. The treated water quality is generally competitive with the secondary effluent from a conventional activated sludge process. With these advantages the FPB bioreactor is recommendable as a compact system for onsite wastewater treatment and reuse. 相似文献
930.
The equilibrium phase of a superconducting network has been investigated below the superconducting critical temperature in the framework of the Ginzburg-Landau theory. It is found that the properties of the mixed state are entirely governed by the flux quantization effect in the loops of the array. Quantitative predictions are made for the spatial configuration of the order parameter, the supercurrents pattern, and the equilibrium magnetization in an extended square network. 相似文献