全文获取类型
收费全文 | 128003篇 |
免费 | 4026篇 |
国内免费 | 452篇 |
专业分类
电工技术 | 1088篇 |
综合类 | 2345篇 |
化学工业 | 20258篇 |
金属工艺 | 5563篇 |
机械仪表 | 3981篇 |
建筑科学 | 3578篇 |
矿业工程 | 636篇 |
能源动力 | 2066篇 |
轻工业 | 10141篇 |
水利工程 | 1661篇 |
石油天然气 | 537篇 |
武器工业 | 4篇 |
无线电 | 11706篇 |
一般工业技术 | 23939篇 |
冶金工业 | 13543篇 |
原子能技术 | 484篇 |
自动化技术 | 30951篇 |
出版年
2023年 | 426篇 |
2022年 | 530篇 |
2021年 | 1212篇 |
2020年 | 1007篇 |
2019年 | 978篇 |
2018年 | 15757篇 |
2017年 | 14729篇 |
2016年 | 11456篇 |
2015年 | 1985篇 |
2014年 | 2028篇 |
2013年 | 3634篇 |
2012年 | 5972篇 |
2011年 | 11718篇 |
2010年 | 10068篇 |
2009年 | 7260篇 |
2008年 | 8625篇 |
2007年 | 9329篇 |
2006年 | 1531篇 |
2005年 | 2323篇 |
2004年 | 2163篇 |
2003年 | 2063篇 |
2002年 | 1363篇 |
2001年 | 655篇 |
2000年 | 713篇 |
1999年 | 739篇 |
1998年 | 3549篇 |
1997年 | 2122篇 |
1996年 | 1416篇 |
1995年 | 826篇 |
1994年 | 719篇 |
1993年 | 687篇 |
1992年 | 249篇 |
1991年 | 267篇 |
1990年 | 233篇 |
1989年 | 243篇 |
1988年 | 217篇 |
1987年 | 180篇 |
1986年 | 197篇 |
1985年 | 226篇 |
1984年 | 196篇 |
1983年 | 134篇 |
1982年 | 167篇 |
1981年 | 180篇 |
1980年 | 158篇 |
1979年 | 133篇 |
1978年 | 118篇 |
1977年 | 202篇 |
1976年 | 429篇 |
1975年 | 91篇 |
1973年 | 82篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Palomares Iván Martínez-Cámara Eugenio Montes Rosana García-Moral Pablo Chiachio Manuel Chiachio Juan Alonso Sergio Melero Francisco J. Molina Daniel Fernández Bárbara Moral Cristina Marchena Rosario de Vargas Javier Pérez Herrera Francisco 《Applied Intelligence》2021,51(9):6497-6527
Applied Intelligence - The17 Sustainable Development Goals (SDGs) established by the United Nations Agenda 2030 constitute a global blueprint agenda and instrument for peace and prosperity... 相似文献
992.
Kwiatkowska Marta Norman Gethin Parker David Santos Gabriel 《Formal Methods in System Design》2021,58(1-2):188-250
Formal Methods in System Design - Automated verification techniques for stochastic games allow formal reasoning about systems that feature competitive or collaborative behaviour among rational... 相似文献
993.
994.
Software Quality Journal - Energy consumption of software has been becoming increasingly significant, since it can vary according to how the software has been developed. In recent years, developers... 相似文献
995.
Radio frequency identification (RFID) tag delegation enables a centralized back-end server to delegate the right to identify
and authenticate a tag to specified readers. This should be used to mitigate the computational load on the server side and
also to solve the issues in terms of latency and dependency on network connectivity. In this study, we describe a basic RFID
delegation architecture and then under this model, we investigate the security of an RFID delegation protocol: Song Mitchell
delegation (SMD), which is recently proposed by Song and Mitchell. We point out security flaws that have gone unnoticed in
the design and present two attacks namely, a tag impersonation attack and a desynchronization attack against it. We also discover
a subtle flaw by which a delegated entity can still keep its delegation rights after the expire of them—this infringes security
policy of the scheme. More precisely, we show that the protocol will be still vulnerable to previously mentioned attacks,
even if the back-end server ends the delegation right of a delegated reader and update the secrets of the delegated tags.
To counteract such flaws, we improve the SMD protocol with a stateful variant so that it provides the claimed security properties. 相似文献
996.
Tomás Sánchez López Damith C. Ranasinghe Mark Harrison Duncan McFarlane 《Personal and Ubiquitous Computing》2012,16(3):291-308
The Internet of Things (IoT) concept is being widely presented as the next revolution toward massively distributed information,
where any real-world object can automatically participate in the Internet and thus be globally discovered and queried. Despite
the consensus on the great potential of the concept and the significant progress in a number of enabling technologies, there
is a general lack of an integrated vision on how to realize it. This paper examines the technologies that will be fundamental
for realizing the IoT and proposes an architecture that integrates them into a single platform. The architecture introduces
the use of the Smart Object framework to encapsulate radio-frequency identification (RFID), sensor technologies, embedded
object logic, object ad-hoc networking, and Internet-based information infrastructure. We evaluate the architecture against
a number of energy-based performance measures, and also show that it outperforms existing industry standards in metrics such
as network throughput, delivery ratio, or routing distance. Finally, we demonstrate the feasibility and flexibility of the
architecture by detailing an implementation using Wireless Sensor Networks and Web Services, and describe a prototype for
the real-time monitoring of goods flowing through a supply chain. 相似文献
997.
We study feedback tracking problems for the planar vertical takeoff and landing (PVTOL) aircraft dynamics, which is a benchmark model in aerospace engineering. We provide a survey of the literature on the model. Then we construct new feedback stabilizers for the PVTOL tracking dynamics. The novelty of our work is in the boundedness of our feedback controllers and their applicability to cases where the velocity measurements may not be available, coupled with the uniform global asymptotic stability and uniform local exponential stability of the closed‐loop tracking dynamics and the input‐to‐state stable performance of the closed‐loop tracking dynamics with respect to actuator errors. Our proofs are based on a new bounded backstepping result. We illustrate our work in a tracking problem along a circle. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
998.
R. Caballero-Águila A. Hermoso-Carazo J. Linares-Pérez 《Digital Signal Processing》2012,22(6):1118-1125
The least-squares linear estimation problem (including prediction, filtering and fixed-point smoothing) from measurements transmitted by different sensors subject to random packet dropouts is addressed. For each sensor, a different Bernoulli sequence is used to model the packet dropout process. Under the assumption that the signal evolution model is unknown, recursive estimation algorithms are derived by an innovation approach, requiring only information about the covariances of the processes involved in the observation equation, as well as the knowledge of the dropout probabilities at each sensor. 相似文献
999.
Marcelo Arenas Jorge Pérez Juan Reutter Cristian Riveros 《The VLDB Journal The International Journal on Very Large Data Bases》2012,21(6):823-842
The inversion of schema mappings has been identified as one of the fundamental operators for the development of a general framework for metadata management. During the last few years, three alternative notions of inversion for schema mappings have been proposed (Fagin-inverse (Fagin, TODS 32(4), 25:1–25:53, 2007), quasi-inverse (Fagin et?al., TODS 33(2), 11:1–11:52, 2008), and maximum recovery (Arenas et?al., TODS 34(4), 22:1–22:48, 2009)). However, these notions lack some fundamental properties that limit their practical applicability: most of them are expressed in languages including features that are difficult to use in practice, some of these inverses are not guaranteed to exist for mappings specified with source-to-target tuple-generating dependencies (st-tgds), and it has been futile to search for a meaningful mapping language that is closed under any of these notions of inverse. In this paper, we develop a framework for the inversion of schema mappings that fulfills all of the above requirements. It is based on the notion of ${\mathcal{C}}$ -maximum recovery, for a query language ${\mathcal{C}}$ , a notion designed to generate inverse mappings that recover back only the information that can be retrieved with queries in ${\mathcal{C}}$ . By focusing on the language of conjunctive queries (CQ), we are able to find a mapping language that contains the class of st-tgds, is closed under CQ-maximum recovery, and for which the chase procedure can be used to exchange data efficiently. Furthermore, we show that our choices of inverse notion and mapping language are optimal, in the sense that choosing a more expressive inverse operator or mapping language causes the loss of these properties. 相似文献
1000.
Lasserre S Hernando J Hill S Schümann F Anasagasti Pde M Jaoudé GA Markram H 《IEEE transactions on visualization and computer graphics》2012,18(2):214-227
We present a process to automatically generate three-dimensional mesh representations of the complex, arborized cell membrane surface of cortical neurons (the principal information processing cells of the brain) from nonuniform morphological measurements. Starting from manually sampled morphological points (3D points and diameters) from neurons in a brain slice preparation, we construct a polygonal mesh representation that realistically represents the continuous membrane surface, closely matching the original experimental data. A mapping between the original morphological points and the newly generated mesh enables simulations of electrophysiolgical activity to be visualized on this new membrane representation. We compare the new mesh representation with the state of the art and present a series of use cases and applications of this technique to visualize simulations of single neurons and networks of multiple neurons. 相似文献