全文获取类型
收费全文 | 37589篇 |
免费 | 3115篇 |
国内免费 | 3143篇 |
专业分类
电工技术 | 3146篇 |
技术理论 | 5篇 |
综合类 | 2431篇 |
化学工业 | 2448篇 |
金属工艺 | 298篇 |
机械仪表 | 1401篇 |
建筑科学 | 1323篇 |
矿业工程 | 185篇 |
能源动力 | 1357篇 |
轻工业 | 454篇 |
水利工程 | 272篇 |
石油天然气 | 229篇 |
武器工业 | 171篇 |
无线电 | 2630篇 |
一般工业技术 | 2953篇 |
冶金工业 | 874篇 |
原子能技术 | 150篇 |
自动化技术 | 23520篇 |
出版年
2024年 | 101篇 |
2023年 | 588篇 |
2022年 | 433篇 |
2021年 | 724篇 |
2020年 | 999篇 |
2019年 | 1073篇 |
2018年 | 1001篇 |
2017年 | 1356篇 |
2016年 | 1465篇 |
2015年 | 1313篇 |
2014年 | 2236篇 |
2013年 | 3444篇 |
2012年 | 1793篇 |
2011年 | 2289篇 |
2010年 | 1655篇 |
2009年 | 2160篇 |
2008年 | 2154篇 |
2007年 | 2153篇 |
2006年 | 1872篇 |
2005年 | 1689篇 |
2004年 | 1415篇 |
2003年 | 1339篇 |
2002年 | 1226篇 |
2001年 | 980篇 |
2000年 | 975篇 |
1999年 | 888篇 |
1998年 | 793篇 |
1997年 | 708篇 |
1996年 | 642篇 |
1995年 | 554篇 |
1994年 | 497篇 |
1993年 | 481篇 |
1992年 | 368篇 |
1991年 | 353篇 |
1990年 | 279篇 |
1989年 | 216篇 |
1988年 | 186篇 |
1987年 | 164篇 |
1986年 | 137篇 |
1985年 | 180篇 |
1984年 | 187篇 |
1983年 | 167篇 |
1982年 | 147篇 |
1981年 | 96篇 |
1980年 | 71篇 |
1979年 | 85篇 |
1978年 | 61篇 |
1977年 | 67篇 |
1976年 | 19篇 |
1975年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
991.
We observe that successive applications of known results from the theory of positive systems lead to an efficient general algorithm for positive realizations of transfer functions. We give two examples to illustrate the algorithm, one of which complements an earlier result of [L. Benvenuti, L. Farina, An example of how positivity may force realizations of ‘large’ dimensions, Systems Control Lett. 36 (1999) 261–266]. Finally, we improve a lower-bound of [B. Nagy, M. Matolcsi, A lower-bound on the dimension of positive realizations, IEEE Trans. Circuits Syst. I 50 (2003) 782–784] to indicate that the algorithm is indeed efficient in general. 相似文献
992.
The problem of stabilizing a second-order SISO LTI system of the form , y=Cx with feedback of the form u(x)=v(x)Cx is considered, where v(x) is real-valued and has domain which is all of . It is shown that, when stabilization is possible, v(x) can be chosen to take on no more than two values throughout the entire state-space (i.e., v(x){k1,k2} for all x and for some k1,k2), and an algorithm for finding a specific choice of v(x) is presented. It is also shown that the classical root locus of the corresponding transfer function C(sI-A)-1B has a strong connection to this stabilization problem, and its utility is demonstrated through examples. 相似文献
993.
control with limited communication and message losses 总被引:2,自引:0,他引:2
We propose an H∞ approach to a remote control problem where the communication is constrained due to the use of a shared channel. The controller employs a periodic time sequencing scheme for message transmissions from multiple sensors and to multiple actuators of the system. It further takes into account the information on the random message losses that occur in the channel. An exact characterization for controller synthesis is obtained and is stated in terms of linear matrix inequalities. Furthermore, an analysis on the loss probabilities of the messages to accomplish stabilization is carried out. The results are illustrated through a numerical example. 相似文献
994.
In the paper, the approximate controllability of linear abstract second-order infinite-dimensional dynamical systems is considered. It is proved using the frequency-domain method, that approximate controllability of second-order system can be verified by the approximate controllability conditions for the corresponding simplified first-order system. General results are then applied for approximate controllability investigation of a vibratory dynamical system modeling flexible mechanical structure. Some special cases are also considered. Moreover, remarks and comments on the relationships between different concepts of controllability are given. The paper extends earlier results on approximate controllability of second-order abstract dynamical systems. 相似文献
995.
This paper proposes a methodology to compute quadratic performance bounds when the closed loop poles of a discrete-time multivariable control loop are confined to a disk, centred at the origin, and with radius less than one. The underlying philosophy in this constraint is to avoid certain undesirable dynamic features which arise in quadratic optimal designs. An expression for the performance loss due to the pole location constraint is also provided. Using numerical examples, we show that the performance loss is compensated by an improved transient performance, specially visible in the control signals. 相似文献
996.
Since its birth, more than five decades ago, one of the biggest challenges of artificial intelligence remained the building of intelligent machines. Despite amazing advancements, we are still far from having machines that reach human intelligence level. The current paper tries to offer a possible explanation of this situation. For this purpose, we make a review of different learning strategies and context types that are involved in the learning process. We also present the results of a study on cognitive development applied to the problem of face recognition for social robotics. 相似文献
997.
This special section is focused on recommendation systems, computer-based information systems that provide suggestions based on previous usage behavior. The papers included in this section were selected from the Pacific Asia Conference on Information Systems (PACIS) and Workshop on Electronic Business (WEB). The application domains include website browsing aids, knowledge recommendation, document clustering, and team staff selection. They provide a snapshot of current development in using recommendation systems for decision support. 相似文献
998.
The rapid propagation of the Internet and information technologies has changed the nature of many industries. Fast response and personalized recommendations have become natural trends for all businesses. This is particularly important for content-related products and services, such as consulting, news, and knowledge management in an organization. The digital nature of their products allows for more customized delivery over the Internet. To provide personalized services, however, a complete understanding of user profile and accurate recommendation are essential.In this paper, an Internet recommendation system that allows customized content to be suggested based on the user's browsing profile is developed. The method adopts a semantic-expansion approach to build the user profile by analyzing documents previously read by the person. Once the customer profile is constructed, personalized contents can be provided by the system. An empirical study using master theses in the National Central library in Taiwan shows that the semantic-expansion approach outperforms the traditional keyword approach in catching user interests. The proper usage of this technology can increase customer satisfaction. 相似文献
999.
Abstract. In this paper we introduce a generalization of Paging to the case where there are many threads of requests. This models situations
in which the requests come from more than one independent source. Hence, apart from deciding how to serve a request, at each stage it is necessary to decide which request to serve among several possibilities.
Four different on-line problems arise depending on whether we consider fairness restrictions or not, with finite or infinite
input sequences. We study all of them, proving lower and upper bounds for the competitiveness of on-line algorithms.
The main competitiveness results presented in this paper state that when no fairness restrictions are imposed it is possible
to obtain competitive algorithms for finite and infinite inputs. On the other hand, for the fair case in general there exist
no competitive algorithms.
In addition, we consider three definitions of competitiveness for infinite inputs. One of them forces algorithms to behave
efficiently at every finite stage, while the other two aim at comparing the algorithms' steady-state performances. A priori,
the three definitions seem different. We study them and find, however, that they are essentially equivalent. This suggests
that the competitiveness results that we obtain reflect the intrinsic difficulty of the problem and are not a consequence
of a too strict definition of competitiveness. 相似文献
1000.
In this paper, we describe an implementation of use in demonstrating the effectiveness of architectures for real-time multi-agent
systems. The implementation provides a simulation of a simplified RoboCup Search and Rescue environment, with unexpected events,
and includes a simulator for both a real-time operating system and a CPU. We present experimental evidence to demonstrate
the benefit of the implementation in the context of a particular hybrid architecture for multi-agent systems that allows certain
agents to remain fully autonomous, while others are fully controlled by a coordinating agent. In addition, we discuss the
value of the implementation for testing any models for the construction of real-time multi-agent systems and include a comparison
to related work.
相似文献
Robin CohenEmail: |