全文获取类型
收费全文 | 228525篇 |
免费 | 20957篇 |
国内免费 | 10056篇 |
专业分类
电工技术 | 14239篇 |
技术理论 | 31篇 |
综合类 | 22884篇 |
化学工业 | 29330篇 |
金属工艺 | 9761篇 |
机械仪表 | 11878篇 |
建筑科学 | 31038篇 |
矿业工程 | 12888篇 |
能源动力 | 8337篇 |
轻工业 | 20343篇 |
水利工程 | 10892篇 |
石油天然气 | 12196篇 |
武器工业 | 3246篇 |
无线电 | 14349篇 |
一般工业技术 | 17275篇 |
冶金工业 | 11752篇 |
原子能技术 | 1896篇 |
自动化技术 | 27203篇 |
出版年
2024年 | 1114篇 |
2023年 | 3171篇 |
2022年 | 5928篇 |
2021年 | 7806篇 |
2020年 | 7620篇 |
2019年 | 5740篇 |
2018年 | 5490篇 |
2017年 | 6658篇 |
2016年 | 8160篇 |
2015年 | 8704篇 |
2014年 | 15581篇 |
2013年 | 14034篇 |
2012年 | 16399篇 |
2011年 | 18075篇 |
2010年 | 13331篇 |
2009年 | 13488篇 |
2008年 | 12336篇 |
2007年 | 15007篇 |
2006年 | 13618篇 |
2005年 | 11879篇 |
2004年 | 9909篇 |
2003年 | 8620篇 |
2002年 | 7049篇 |
2001年 | 5794篇 |
2000年 | 4942篇 |
1999年 | 3882篇 |
1998年 | 2770篇 |
1997年 | 2450篇 |
1996年 | 1969篇 |
1995年 | 1648篇 |
1994年 | 1382篇 |
1993年 | 1007篇 |
1992年 | 819篇 |
1991年 | 553篇 |
1990年 | 495篇 |
1989年 | 456篇 |
1988年 | 259篇 |
1987年 | 215篇 |
1986年 | 188篇 |
1985年 | 215篇 |
1984年 | 154篇 |
1983年 | 124篇 |
1982年 | 77篇 |
1981年 | 80篇 |
1980年 | 87篇 |
1979年 | 38篇 |
1978年 | 22篇 |
1977年 | 22篇 |
1975年 | 16篇 |
1959年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
991.
In this paper,adaptive dynamic surface control(DSC) is developed for a class of nonlinear systems with unknown discrete and distributed time-varying delays and unknown dead-zone.Fuzzy logic systems are used to approximate the unknown nonlinear functions.Then,by combining the backstepping technique and the appropriate Lyapunov-Krasovskii functionals with the dynamic surface control approach,the adaptive fuzzy tracking controller is designed.Our development is able to eliminate the problem of "explosion of complexity" inherent in the existing backstepping-based methods.The main advantages of our approach include:1) for the n-th-order nonlinear systems,only one parameter needs to be adjusted online in the controller design procedure,which reduces the computation burden greatly.Moreover,the input of the dead-zone with only one adjusted parameter is much simpler than the ones in the existing results;2) the proposed control scheme does not need to know the time delays and their upper bounds.It is proven that the proposed design method is able to guarantee that all the signals in the closed-loop system are bounded and the tracking error is smaller than a prescribed error bound,Finally,simulation results demonstrate the effectiveness of the proposed approach. 相似文献
992.
C. Christopher ColumbusAuthor Vitae K. Chandrasekaran Author VitaeSishaj P. Simon Author Vitae 《Applied Soft Computing》2012,12(1):145-160
This paper proposes a nodal ant colony optimization (NACO) technique to solve profit based unit commitment problem (PBUCP). Generation companies (GENCOs) in a competitive restructured power market, schedule their generators with an objective to maximize their own profit without any regard for system social benefit. Power and reserve prices become important factors in decision process. Ant colony optimization that mimics the behavior of ants foraging activities is suitably implemented to search the UCP search space. Here a search space consisting of optimal combination of binary nodes for unit ON/OFF status is represented for the movement of the ants to maintain good exploration and exploitation search capabilities. The proposed model help GENCOs to make decisions on the quantity of power and reserve that must be put up for sale in the markets and also to schedule generators in order to receive the maximum profit. The effectiveness of the proposed technique for PBUCP is validated on 10 and 36 generating unit systems available in the literature. NACO yields an increase of profit, greater than 1.5%, in comparison with the basic ACO, Muller method and hybrid LR-GA. 相似文献
993.
994.
Drury CG 《Applied ergonomics》1989,20(4):261-266
An evaluation of a consumer product is presented as an example of how ergonomics models can guide data collection and interpretation by non-ergonomists. The product, a new cooking pan, was compared with its earlier counterpart on performance and safety tests for specific features. Model-guided evaluations produced data which could be well-fitted by linear relationships, and measures derived from the data could be interpreted in physical terms by engineers. This is now the standard methodology for pan evaluation in the client company. 相似文献
995.
Xiuming Huang 《Machine Translation》1988,3(2):101-120
This paper concerns the resolution of lexical ambiguity in a machine translation environment. We describe the integration of principles of selection restrictions. Preference Semantics, and intelligent relaxation of constraints in handling lexical ambiguity. The approach differs from many previous MT systems in that it is more powerful than brute force systems, while more realistic than systems that assume a large degree of coded encyclopedia information for full understanding. 相似文献
996.
997.
John A. Hughes Dave Randall Dan Shapiro 《Computer Supported Cooperative Work (CSCW)》1992,1(3):123-141
This paper explores the issues involved in moving from ethnographic explorations of work in context to a practical contribution to system design. It does so using the example of an interdisciplinary research project involving sociologists and computer scientists in the domain of air traffic control systems. It forms a pair with another paper (Sommerville et al., 1992) exploring these questions from the perspective of our computer science partners. We characterise ethnography as a research method, and consider the differences between undertaking it for strictly sociological or anthropological purposes by contrast with interdisciplinary and design purposes. We summarise some of our results in ethnographic explications of the work of air traffic controllers, and the sociality which it manifests. We describe the dialogues involved in rendering these observations informative for systems design, and the mutual translations implied in attempting to reconcile sociological with software engineering questions about supporting the work. We conclude by specifying some features of cooperative work which an engineering approach is in danger of overlooking; the ways, and limits, in which ethnographers can form a bridge between users and designers; and some of the conflicts of interest entrained in generating technical change.The research is funded by the UK MRC/SERC/ESRC Cognitive Science/HCI Initiative with the title Social Analysis of Control Systems for HCI Design, grant number SPG 8931598. The computer science partners are Professor Ian Sommerville, Dr Tom Rodden, Dr Pete Sawyer and Mr Richard Bentley. Thanks are due to Val King, Kjeldt Schmidt, Ian Sommerville and Tom Rodden for very helpful comments on earlier drafts of this paper. 相似文献
998.
999.
1000.