全文获取类型
收费全文 | 75267篇 |
免费 | 728篇 |
国内免费 | 689篇 |
专业分类
电工技术 | 1430篇 |
综合类 | 48篇 |
化学工业 | 11219篇 |
金属工艺 | 3452篇 |
机械仪表 | 2641篇 |
建筑科学 | 1653篇 |
矿业工程 | 504篇 |
能源动力 | 1858篇 |
轻工业 | 6426篇 |
水利工程 | 858篇 |
石油天然气 | 2303篇 |
武器工业 | 41篇 |
无线电 | 7260篇 |
一般工业技术 | 16535篇 |
冶金工业 | 12539篇 |
原子能技术 | 2640篇 |
自动化技术 | 5277篇 |
出版年
2022年 | 586篇 |
2021年 | 919篇 |
2020年 | 721篇 |
2019年 | 795篇 |
2018年 | 1559篇 |
2017年 | 1571篇 |
2016年 | 1771篇 |
2015年 | 952篇 |
2014年 | 1566篇 |
2013年 | 3581篇 |
2012年 | 2365篇 |
2011年 | 2848篇 |
2010年 | 2381篇 |
2009年 | 2651篇 |
2008年 | 2631篇 |
2007年 | 2568篇 |
2006年 | 2196篇 |
2005年 | 1928篇 |
2004年 | 1847篇 |
2003年 | 1799篇 |
2002年 | 1711篇 |
2001年 | 1684篇 |
2000年 | 1683篇 |
1999年 | 1569篇 |
1998年 | 3693篇 |
1997年 | 2623篇 |
1996年 | 1943篇 |
1995年 | 1526篇 |
1994年 | 1336篇 |
1993年 | 1361篇 |
1992年 | 1003篇 |
1991年 | 1058篇 |
1990年 | 1075篇 |
1989年 | 1054篇 |
1988年 | 946篇 |
1987年 | 878篇 |
1986年 | 882篇 |
1985年 | 939篇 |
1984年 | 778篇 |
1983年 | 773篇 |
1982年 | 677篇 |
1981年 | 699篇 |
1980年 | 663篇 |
1979年 | 651篇 |
1978年 | 622篇 |
1977年 | 779篇 |
1976年 | 941篇 |
1975年 | 582篇 |
1974年 | 555篇 |
1973年 | 549篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
A stability robustness test is developed for internally stable, nominal, linear time‐invariant (LTI) feedback systems subject to structured, linear time‐varying uncertainty. There exists (in the literature) a necessary and sufficient structured small gain condition that determines robust stability in such cases. In this paper, the structured small gain theorem is utilized to formulate a (sufficient) stability robustness condition in a scaled LTI ν‐gap metric framework. The scaled LTI ν‐gap metric stability condition is shown to be computable via linear matrix inequality techniques, similar to the structured small gain condition. Apart from a comparison with a generalized robust stability margin as the final part of the stability test, however, the solution algorithm implemented to test the scaled LTI ν‐gap metric stability robustness condition is shown to be independent of knowledge about the controller transfer function (as opposed to the LMI feasibility problem associated with the scaled small gain condition which is dependent on knowledge about the controller). Thus, given a nominal plant and a structured uncertainty set, the stability robustness condition presented in this paper provides a single constraint on a controller (in terms of a large enough generalized robust stability margin) that (sufficiently) guarantees to stabilize all plants in the uncertainty set. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
992.
I. A. Boguslavskii O. V. Kruglyakova N. Ya. Miroshichev G. M. Tsimbalyuk 《Journal of Computer and Systems Sciences International》2009,48(3):333-344
The parameter identification problem for the nonlinear dynamic system of a sufficiently general form, in which the multipolynomial approximation algorithm processes measured data, is considered. To show the efficiency of the algorithm, an example of parameter identification for a nonlinear dynamic system with non-differentiable right-hand side is given and the identification problem for aerodynamic parameters of aircraft pitching motion is solved. 相似文献
993.
R. I. Kozlov O. R. Kozlova 《Journal of Computer and Systems Sciences International》2009,48(2):262-271
Modification and extension of procedures of strict analysis of stability and estimates of domains of attraction based on the reduction method with sublinear vector Lyapunov function is given for sufficiently wide class of nonlinear stabilization systems of continuous objects using piecewise constant control formed using discrete state measurements. The new type of realization of heterogeneous comparison systems in the form of interconnected differential and discrete impulse subsystems with varying right-hand side allowing to avoid preliminary discretization of the original system and thus increasing accuracy of investigations is proposed. In the case of nonlinearities (including those with respect to control and measurements), limited by semi-homogeneous functions. Constructive conditions of exponential stability with necessary quantitative estimates are formulated. Application to investigation of stability of economic growth in the Phillips-Bergstrom model with discrete monetary regulation is presented. The paper consists of two parts. In this part, the studied models are described, the studied stability property is defined, procedures for construction of vector Lyapunov function and comparison system are given, and some of their specific features are established. 相似文献
994.
John Strassner Sven van der Meer Declan O’Sullivan Simon Dobson 《Journal of Network and Systems Management》2009,17(3):255-284
The purpose of autonomic networking is to manage the business and technical complexity of networked components and systems.
However, existing network management data has no link to business concepts. This makes it very difficult to ensure that services
offered by the network are meeting business objectives. This paper describes a novel context-aware policy model that uses
a combination of modeled and ontological data to determine the current context, which policies are applicable to that context,
and what services and resources should be offered to which users and applications.
John Strassner is the director of autonomic research in the Telecommunications Systems & Software Group in Waterford Institute of Technology, and a Visiting Professor at POSTECH. His research interests are in autonomic systems, policy based management, machine learning, and semantic reasoning. He is the Chairman of the Autonomic Communications Forum, and the past chair of the TMF’s NGOSS SID, metamodel and policy working groups. He has authored two books, written chapters for five other books, and co-edited five journals on network and service management and autonomics. John is the recipient of the Daniel A. Stokesbury memorial award for excellence in network management, and has authored 211 refereed journal papers and publications. Sven van der Meer received his M.Sc in computer science and his Dr.-Ing. from Technical University Berlin (TUB), Germany, in 1996 and 2002. Since November 2002, Sven has been a research fellow at the Telecommunications Software & Systems Group at the Waterford Institute of Technology. Since October 2004 he is Senior Investigator of the Competence Centre for Communication Infrastructure Management at TSSG, involved in the Architecture and Information Modelling teams in the TMF, and has served as editor for Technological Neutral Architecture and Contracts specifications within the TM Forum. Declan O’Sullivan is the director of the Knowledge and Data Engineering (KDEG) research group in Trinity College Dublin (TCD). His research interests are in the use of semantic-driven approaches for network and service management, in particular to enable semantic interoperability. He is currently a Principal Investigator in the SFI funded research project investigating Federated Autonomic Management Environments (FAME). O’Sullivan has a Ph.D. and a M.Sc in computer science from TCD. Simon Dobson is a co-founder of the Systems Research Group at UCD Dublin. His research centers around adaptive pervasive computing and novel programming techniques. He is on the editorial boards of the Journal of Network and Systems Management and the International Journal of Autonomous and Adaptive Communications Systems, and participates in a number of EU strategic workshops and working groups. He is National Director and vice-president of the European Research Consortium for Informatics and Mathematics, a board member of the Autonomic Communication Forum, and a member of the IBEC/ICT Ireland standing committee on academic/industrial research and development. He holds a BSc and DPhil in computer science, is a Chartered Fellow of the British Computer Society, a Chartered Engineer, and member of the IEEE and ACM. 相似文献
Simon DobsonEmail: |
John Strassner is the director of autonomic research in the Telecommunications Systems & Software Group in Waterford Institute of Technology, and a Visiting Professor at POSTECH. His research interests are in autonomic systems, policy based management, machine learning, and semantic reasoning. He is the Chairman of the Autonomic Communications Forum, and the past chair of the TMF’s NGOSS SID, metamodel and policy working groups. He has authored two books, written chapters for five other books, and co-edited five journals on network and service management and autonomics. John is the recipient of the Daniel A. Stokesbury memorial award for excellence in network management, and has authored 211 refereed journal papers and publications. Sven van der Meer received his M.Sc in computer science and his Dr.-Ing. from Technical University Berlin (TUB), Germany, in 1996 and 2002. Since November 2002, Sven has been a research fellow at the Telecommunications Software & Systems Group at the Waterford Institute of Technology. Since October 2004 he is Senior Investigator of the Competence Centre for Communication Infrastructure Management at TSSG, involved in the Architecture and Information Modelling teams in the TMF, and has served as editor for Technological Neutral Architecture and Contracts specifications within the TM Forum. Declan O’Sullivan is the director of the Knowledge and Data Engineering (KDEG) research group in Trinity College Dublin (TCD). His research interests are in the use of semantic-driven approaches for network and service management, in particular to enable semantic interoperability. He is currently a Principal Investigator in the SFI funded research project investigating Federated Autonomic Management Environments (FAME). O’Sullivan has a Ph.D. and a M.Sc in computer science from TCD. Simon Dobson is a co-founder of the Systems Research Group at UCD Dublin. His research centers around adaptive pervasive computing and novel programming techniques. He is on the editorial boards of the Journal of Network and Systems Management and the International Journal of Autonomous and Adaptive Communications Systems, and participates in a number of EU strategic workshops and working groups. He is National Director and vice-president of the European Research Consortium for Informatics and Mathematics, a board member of the Autonomic Communication Forum, and a member of the IBEC/ICT Ireland standing committee on academic/industrial research and development. He holds a BSc and DPhil in computer science, is a Chartered Fellow of the British Computer Society, a Chartered Engineer, and member of the IEEE and ACM. 相似文献
995.
Brdiczka O. Crowley J.L. Reignier P. 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2009,39(1):56-63
This paper addresses the problem of learning situation models for providing context-aware services. Context for modeling human behavior in a smart environment is represented by a situation model describing environment, users, and their activities. A framework for acquiring and evolving different layers of a situation model in a smart environment is proposed. Different learning methods are presented as part of this framework: role detection per entity, unsupervised extraction of situations from multimodal data, supervised learning of situation representations, and evolution of a predefined situation model with feedback. The situation model serves as frame and support for the different methods, permitting to stay in an intuitive declarative framework. The proposed methods have been integrated into a whole system for smart home environment. The implementation is detailed, and two evaluations are conducted in the smart home environment. The obtained results validate the proposed approach. 相似文献
996.
J.J. Sharples R.H.D. McRae R.O. Weber A.M. Gill 《Environmental Modelling & Software》2009,24(5):637-646
Assessing fuel moisture content to within a reasonable degree of accuracy is an important part of wildland fire management. In this paper we introduce a fuel moisture index that provides a simple and intuitive method for assessing fuel moisture content. The method can be quickly and easily applied in a field setting to provide a dimensionless measure of fuel moisture content. We compare the index with predictions from several models for fuel moisture content and conclude that it provides an equivalent measure of fuel moisture content for a number of fuel types. We go on to briefly discuss how the index could be used to construct a simple and intuitive fire danger index. 相似文献
997.
J.J. Sharples R.H.D. McRae R.O. Weber A.M. Gill 《Environmental Modelling & Software》2009,24(6):764-774
Fire danger rating systems are used to assess the potential for bushfire occurrence, fire spread and difficulty of fire suppression. Typically, fire danger rating systems combine meteorological information with estimates of the moisture content of the fuel to produce a fire danger index. Fire danger indices are used to declare fire bans and to schedule prescribed burns, among other applications. In this paper a simple fire danger index F that is intuitive and easy to calculate is introduced and compared to a number of fire danger indices pertaining to different fuel types that are used in an operational setting in Australia and the United States. The comparisons suggest that F provides a plausible measure of fire danger rating and that it may be a useful pedagogical tool in the context of fire danger and fire weather. 相似文献
998.
This paper provides a new approach to the bipedal robot stability problems in presence of external disturbances in vertical
posture of the robot, during walking and during object handling. This approach is based on synergy between the dynamic motions
of balancing masses and arms to reject large perturbations applied to the upper part of ROBIAN robot. In these cases, the
stabilization is carried out in the first time with a trunk having 4 degrees of freedom (dof): one rotational and three translational
movements. In the second time, the stabilization is performed with a system with arms and having 10 dof. During the walk,
the trunk elements of ROBIAN reproduce necessary movements to perform the dynamic walking gait of the robot. The compensation
of external three-dimensional efforts applied to the robot is achieved firstly by the trunk and secondly with the arms. This
study allows us to determine on-line the required movements and accelerations of the trunk elements in order to maintain the
robot stability and shows the importance of the arms for the robot stability. 相似文献
999.
Longy O. Anyanwu Jared Keengwe Gladys A. Arome 《通讯和计算机》2009,6(12):38-46
Each lnternet communication leaves trails that can be followed back to the user. Notably, anonymous communication schemes are purposed to hide users' identity as to personal, source, destination location and content information. Notably, no network capability is in existence to completely negate anonymity leakage in network latency[~l, thus, the minimization of anonymity leakage in network latency becomes critically salient. The purpose of this paper is to investigate network latency anonymity leaks, and propose practical techniques for their reduction. In this direction, the author investigate the following technical question: What implementation techniques can be configured to truly reduce anonymity leaks using deployable systems and exploiting the popular Tor security strategies. 相似文献
1000.
Pierrot F. Nabat V. Company O. Krut S. Poignet P. 《Robotics, IEEE Transactions on》2009,25(2):213-224
This paper presents an optimal design of a parallel manipulator aiming to perform pick-and-place operations at high speed and high acceleration. After reviewing existing architectures of high-speed and high-acceleration parallel manipulators, a new design of a 4-DOF parallel manipulator is presented, with an articulated traveling plate, which is free of internal singularities and is able to achieve high performances. The kinematic and simplified, but realistic, dynamic models are derived and validated on a manipulator prototype. Experimental tests show that this design is able to perform beyond the high targets, i.e., it reaches a speed of 5.5 m/s and an acceleration of 165 m/s2. The experimental prototype was further optimized on the basis of kinematic and dynamic criteria. Once the motors, gear ratio, and several link lengths are determined, a modified design of the articulated traveling plate is proposed in order to reach a better dynamic equilibrium among the four legs of the manipulator. The obtained design is the basis of a commercial product offering the shortest cycle times among all robots available in today's market. 相似文献