全文获取类型
收费全文 | 60949篇 |
免费 | 4049篇 |
国内免费 | 64篇 |
专业分类
电工技术 | 944篇 |
综合类 | 688篇 |
化学工业 | 17823篇 |
金属工艺 | 1110篇 |
机械仪表 | 1061篇 |
建筑科学 | 1897篇 |
矿业工程 | 135篇 |
能源动力 | 1407篇 |
轻工业 | 9095篇 |
水利工程 | 511篇 |
石油天然气 | 240篇 |
武器工业 | 8篇 |
无线电 | 2081篇 |
一般工业技术 | 9509篇 |
冶金工业 | 10690篇 |
原子能技术 | 289篇 |
自动化技术 | 7574篇 |
出版年
2023年 | 916篇 |
2022年 | 1125篇 |
2021年 | 1908篇 |
2020年 | 1532篇 |
2019年 | 1603篇 |
2018年 | 2118篇 |
2017年 | 2006篇 |
2016年 | 2259篇 |
2015年 | 1966篇 |
2014年 | 2427篇 |
2013年 | 4328篇 |
2012年 | 3173篇 |
2011年 | 3313篇 |
2010年 | 2970篇 |
2009年 | 2968篇 |
2008年 | 2350篇 |
2007年 | 2085篇 |
2006年 | 1582篇 |
2005年 | 1420篇 |
2004年 | 1380篇 |
2003年 | 1207篇 |
2002年 | 1174篇 |
2001年 | 790篇 |
2000年 | 741篇 |
1999年 | 808篇 |
1998年 | 3346篇 |
1997年 | 2277篇 |
1996年 | 1556篇 |
1995年 | 982篇 |
1994年 | 788篇 |
1993年 | 933篇 |
1992年 | 390篇 |
1991年 | 381篇 |
1990年 | 308篇 |
1989年 | 340篇 |
1988年 | 307篇 |
1987年 | 305篇 |
1986年 | 281篇 |
1985年 | 309篇 |
1984年 | 260篇 |
1983年 | 243篇 |
1982年 | 246篇 |
1981年 | 290篇 |
1980年 | 281篇 |
1979年 | 167篇 |
1978年 | 139篇 |
1977年 | 423篇 |
1976年 | 800篇 |
1975年 | 139篇 |
1973年 | 217篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
ABSTRACTIn this paper, we review some algebraic control system. Precisely, linear and bilinear systems on Euclidean spaces and invariant and linear systems on Lie groups. The fourth classes of systems have a common issue: to any class, there exists an associated subgroup. From this object, we survey the controllability property. Especially, from those coming from our contribution to the theory. 相似文献
2.
3.
Ohne Zusammenfassung 相似文献
4.
E. Griese Prof. Dr.-Ing. 《e & i Elektrotechnik und Informationstechnik》2003,120(6):186-191
Optical interconnection technology on the printed circuit board level is a key technology for future microelectronic equipment. The consideration of functional, technological, and economical requirements results in a hybrid solution, where electrical and optical interconnects are integrated into one substrate called electrical optical printed circuit board. The significant part of the entire design process for electrical optical printed circuit boards is marked by the design supporting modelling and simulation of optical interconnects. Based on an abstract model for an entire optical interconnect a simulation model for optical multimode-waveguides is presented, taking into account all significant waveguide properties. Apart from that, the modeling of active components (laser- and photo-diodes) is addressed. 相似文献
5.
The tensile elastic modulus (E), yield stress (σY) and microhardness (MH) of neat and binary and ternary blends of glassy semicrystalline ethylene–vinyl alcohol copolymer (EVOH), a glassy amorphous polyamide and a semicrystalline nylon‐containing ionomer covering a broad range of properties were examined. The tests were carried out on dry and water‐equilibrated samples to produce stiffer and softer materials, respectively. From the results, more accurate linear correlations were found to describe adequately the microhardness, modulus and yield stress of these strongly self‐associated polymers through hydrogen bonding. Copyright © 2003 Society of Chemical Industry 相似文献
6.
Kruk Menno R.; Halász József; Meelis Wout; Haller József 《Canadian Metallurgical Quarterly》2004,118(5):1062
Aggressive behavior induces an adrenocortical stress response, and sudden stressors often precipitate violent behavior. Experiments in rats revealed a fast, mutual, positive feedback between the adrenocortical stress response and a brain mechanism controlling aggression. Stimulation of the aggressive area in the hypothalamus rapidly activated the adrenocortical response, even in the absence of an opponent and fighting. Hypothalamic aggression, in turn, was rapidly facilitated by a corticosterone injection in rats in which the natural adrenocortical stress response was prevented by adrenalectomy. The rapidity of both effects points to a fast, mutual, positive feedback of the controlling mechanisms within the time frame of a single conflict. Such a mutual facilitation may contribute to the precipitation and escalation of violent behavior under stressful conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
Eduardo Freire Teodiano Bastos-Filho Mário Sarcinelli-Filho Ricardo Carelli 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2004,34(1):419-429
This paper proposes an alternative approach to address the problem of coordinating behaviors in mobile robot navigation: fusion of control signals. Such approach is based on a set of two decentralized information filters, which accomplish the data fusion involved. Besides these two fusion engines, control architectures designed according to this approach also embed a set of different controllers that generate reference signals for the robot linear and angular speeds. Such signals are delivered to the two decentralized information filters, which estimate suitable overall reference signals for the robot linear and angular speeds, respectively. Thus, the background for designing such control architectures is provided by the nonlinear systems theory, which makes this approach different from any other yet proposed. This background also allows checking control architectures designed according to the proposed approach for stability. Such analysis is carried out in the paper, and shows that the robot always reaches its final destination, in spite of either obstacles along its path or the environment layout. As an example, a control architecture is designed to guide a mobile robot in an experiment, whose results allows checking the good performance of the control architecture and validating the design approach proposed as well. 相似文献
8.
The three-dimensional morphology of polyethylene single crystals grown from dilute solution has been examined by atomic force microscopy. Single crystals were deposited on a soft ground of aqueous solution of poly(vinyl alcohol) (PVA) to avoid the collapse of thin lamellar crystals with thickness of 10 nm. The observation of single crystals on dried PVA clarifies the morphology of a chair type crystal as well as well-known hollow pyramidal type. It has been confirmed that the screw dislocations in the chair type follow a selection rule of the handedness in a manner to relieve the distortion in the chair type. 相似文献
9.
10.