全文获取类型
收费全文 | 24468篇 |
免费 | 2643篇 |
国内免费 | 1380篇 |
专业分类
电工技术 | 1797篇 |
技术理论 | 4篇 |
综合类 | 1973篇 |
化学工业 | 3758篇 |
金属工艺 | 1324篇 |
机械仪表 | 1638篇 |
建筑科学 | 1985篇 |
矿业工程 | 834篇 |
能源动力 | 822篇 |
轻工业 | 1687篇 |
水利工程 | 583篇 |
石油天然气 | 1234篇 |
武器工业 | 235篇 |
无线电 | 3067篇 |
一般工业技术 | 2860篇 |
冶金工业 | 1120篇 |
原子能技术 | 238篇 |
自动化技术 | 3332篇 |
出版年
2024年 | 142篇 |
2023年 | 485篇 |
2022年 | 884篇 |
2021年 | 1204篇 |
2020年 | 968篇 |
2019年 | 745篇 |
2018年 | 863篇 |
2017年 | 898篇 |
2016年 | 851篇 |
2015年 | 1084篇 |
2014年 | 1382篇 |
2013年 | 1554篇 |
2012年 | 1725篇 |
2011年 | 1787篇 |
2010年 | 1612篇 |
2009年 | 1387篇 |
2008年 | 1409篇 |
2007年 | 1223篇 |
2006年 | 1194篇 |
2005年 | 1000篇 |
2004年 | 759篇 |
2003年 | 817篇 |
2002年 | 885篇 |
2001年 | 777篇 |
2000年 | 597篇 |
1999年 | 451篇 |
1998年 | 341篇 |
1997年 | 275篇 |
1996年 | 283篇 |
1995年 | 211篇 |
1994年 | 160篇 |
1993年 | 106篇 |
1992年 | 97篇 |
1991年 | 71篇 |
1990年 | 62篇 |
1989年 | 51篇 |
1988年 | 43篇 |
1987年 | 30篇 |
1986年 | 22篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 5篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
This paper investigates almost sure exponential stability and feedback stabilization for switched time‐delay systems with nonlinear stochastic perturbations. The main contributions of this paper are threefold: (i) based on the non‐convolution type multiple Lyapunov functionals and the mathematical induction approach, a mean‐square exponential stability condition for nonlinear stochastic switched systems is first established, such that the obtained average dwell time does not rely on any given decay rate; (ii) by using the method developed in part (i) and the stochastic analysis techniques and limit methods in probability, an almost sure exponential stability criterion for switched delayed systems with nonlinear stochastic uncertainties is presented, and then a state feedback controller for the systems under consideration is designed; and (iii) when certain assumptions are made on the nonlinear stochastic perturbations, the results in this paper are further improved by relaxing some conditions. The effectiveness of the proposed method is demonstrated by three illustrative examples. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
92.
Multi-agent technologies have been widely employed for the development of web-based systems, including web-based e-markets, web-based grid computing, e-governments and service-oriented software systems. In these service-oriented systems, service provider agents and service consumer agents are autonomous and rational entities, which can enter and leave the environments freely. For simplicity, we use terms ‘provider’ and ‘consumer’ to represent this two types of agents. How to select the most suitable service providers according to a service request from a consumer in such an open environment is a very challenging issue. In this paper, we propose an innovative trust model, called the GTrust model, for service group selection in general service-oriented environments. In the GTrust model, the trust evaluation for a service group is based on the functionality coverage of the group, the dependency relationships among individual services in the group, the ratings of individual services on the attributes of the service request and a similarity measurement of the extent to which reference reports can reflect the service request in terms of the priority distribution of attributes. The experimental results and analysis demonstrate the good performance of the GTrust model on the service group selection in service-oriented environments. 相似文献
93.
94.
95.
计算机所具有的连接方式因其多样性、应用技术复杂性和网络广泛性以及互相关联性等特征,导致计算机网络信息存储安全问题的出现并且愈发复杂。针对来自各方面的诸多威胁和系统本身的脆弱性,通过建立计算机网络信息的危险控制模型、控制网络信息访问数据、鉴别网络信息用户身份等方法,制定出计算机网络信息存储安全的具体措施,以此来保证存储信息系统的运行安全。 相似文献
96.
为了满足民用飞机在飞行试验中高速摄像机对时间同步的需求,基于国产北斗卫星导航系统设计了具有精确输出IRIG-B(AC)码的时间同步器,用于机载高速摄像机的精确时间同步。以FPGA为核心,使用直接数字频率合成技术实现了IRIG-B(AC)码的产生。实验结果表明,该同步器时间同步精度满足要求,可以实现对高速摄像机进行时间同步的功能。 相似文献
97.
This paper is concerned with the self‐triggered output feedback control for discrete‐time systems, where an updating instants scheduler is implemented to determine when the controller is updated. For both the full‐order and reduced‐order observer cases, the updating instants are determined, respectively, where only the information of the estimated state at the current updating instant is required to obtain the next updating instant. It is shown that, with the proposed self‐triggered control schemes, not only the updating frequency is significantly reduced, but also the uniform ultimate boundedness of the closed‐loop system is guaranteed. Finally, a numerical example is used to verify the effectiveness and the merits of the proposed approaches. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
98.
This work presents the design of a novel static-triggered power-rail electrostatic discharge (ESD) clamp circuit. The superior transient-noise immunity of the static ESD detection mechanism over the transient one is firstly discussed. Based on the discussion, a novel power-rail ESD clamp circuit utilizing the static ESD detection mechanism is proposed. By skillfully incorporating a thyristor delay stage into the trigger circuit (TC), the proposed circuit achieves the best ESD-conduction behavior while consuming the lowest leakage current (Ileak) at the normal bias voltage among all investigated circuits in this work. In addition, the proposed circuit achieves an excellent false-triggering immunity against fast power-up pulses. All investigated circuits are fabricated in a 65-nm CMOS process. Performance superiorities of the proposed circuit are fully verified by both simulation and test results. Moreover, the proposed circuit offers an efficient on-chip ESD protection scheme considering the worst discharge case in the utilized process. 相似文献
99.
Lei Gao Shuo Zhang Ziyao Liu Jinyong Lin Shuai Wang Chengwen Xing 《中国科学:信息科学(英文版)》2016,59(12):121301
Multi-antenna technologies have already achieved a series of great successes in the development of information networks. For future space-ground integrated networks (SGINs), the traditional various kinds of separated information networks will converge to a whole fully connected information network to provide more flexible and reliable services on a world scale. Regarding their great successes in existing systems, multiantenna technologies will be of critical importance for the realization of SGINs and multi-antenna technologies are definitely one of the most important enabling technologies for future converged SGINs. In this article, a comprehensive overview on multi-antenna technologies is given. We first investigate multi-antenna technologies from a theoretical viewpoint. It is shown that we can understand multi-antenna technologies in a general and unified point of view. This fact has two-fold meanings. First, the research on multi-antennas can help us understand the relationships between different technologies e.g., OFDMA, CDMA, etc. On the other hand, multi-antenna technologies are easy to integrate into various information systems. Following that, we discuss in depth the potentials and challenges of the multi-antenna technologies on different platforms and in different applications case by case. More specifically, we investigate spaceborne multi-antenna technologies, airborne multi-antenna technologies, shipborne multi-antenna technologies, etc. Moreover, the combinations of multiantenna technologies with other advanced wireless technologies e.g., physical layer network coding, cooperative communication, etc., are also elaborated. 相似文献
100.