全文获取类型
收费全文 | 3584篇 |
免费 | 258篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 13篇 |
综合类 | 2篇 |
化学工业 | 1557篇 |
金属工艺 | 48篇 |
机械仪表 | 59篇 |
建筑科学 | 88篇 |
矿业工程 | 6篇 |
能源动力 | 82篇 |
轻工业 | 686篇 |
水利工程 | 17篇 |
石油天然气 | 16篇 |
无线电 | 137篇 |
一般工业技术 | 541篇 |
冶金工业 | 150篇 |
原子能技术 | 11篇 |
自动化技术 | 430篇 |
出版年
2024年 | 6篇 |
2023年 | 75篇 |
2022年 | 409篇 |
2021年 | 357篇 |
2020年 | 125篇 |
2019年 | 124篇 |
2018年 | 138篇 |
2017年 | 150篇 |
2016年 | 136篇 |
2015年 | 108篇 |
2014年 | 157篇 |
2013年 | 214篇 |
2012年 | 232篇 |
2011年 | 240篇 |
2010年 | 173篇 |
2009年 | 181篇 |
2008年 | 172篇 |
2007年 | 147篇 |
2006年 | 115篇 |
2005年 | 97篇 |
2004年 | 76篇 |
2003年 | 61篇 |
2002年 | 59篇 |
2001年 | 34篇 |
2000年 | 28篇 |
1999年 | 34篇 |
1998年 | 34篇 |
1997年 | 28篇 |
1996年 | 25篇 |
1995年 | 19篇 |
1994年 | 9篇 |
1993年 | 12篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1989年 | 4篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 6篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1971年 | 4篇 |
1969年 | 2篇 |
1934年 | 1篇 |
排序方式: 共有3843条查询结果,搜索用时 31 毫秒
71.
David Schleicher Luis M. Bergasa Manuel Ocaña Rafael Barea Elena López 《Robotics and Autonomous Systems》2010,58(8):991-1002
In this paper we present a new real-time hierarchical (topological/metric) Visual SLAM system focusing on the localization of a vehicle in large-scale outdoor urban environments. It is exclusively based on the visual information provided by a cheap wide-angle stereo camera. Our approach divides the whole map into local sub-maps identified by the so-called fingerprints (vehicle poses). At the sub-map level (low level SLAM), 3D sequential mapping of natural landmarks and the robot location/orientation are obtained using a top-down Bayesian method to model the dynamic behavior. A higher topological level (high level SLAM) based on fingerprints has been added to reduce the global accumulated drift, keeping real-time constraints. Using this hierarchical strategy, we keep the local consistency of the metric sub-maps, by mean of the EKF, and global consistency by using the topological map and the MultiLevel Relaxation (MLR) algorithm. Some experimental results for different large-scale outdoor environments are presented, showing an almost constant processing time. 相似文献
72.
Maria Elena Bruni Francesca Guerriero 《International Transactions in Operational Research》2010,17(2):207-220
The aim of this paper is to investigate the use of heuristic information to efficiently solve to optimality the robust shortest path problem. Starting from the exact algorithm proposed by Murty and Her, we describe how this algorithm can be enhanced by using heuristic rules and evaluation functions to guide the search. The efficiency of the proposed enhanced approach is tested over a range of random generated instances. Our computational results indicate that the use of heuristic criteria is able to speed up considerably the search and that the enhanced exact solution method outperforms the state‐of‐the‐art algorithm proposed by Murty and Her in most of the instances. 相似文献
73.
74.
A synchronizing word for a given synchronizing DFA is called minimal if none of its proper factors is synchronizing. We characterize the class of synchronizing automata having only finitely many minimal synchronizing words (the class of such automata is denoted by FG). Using this characterization we prove that any such automaton possesses a synchronizing word of length at most 3n-5. We also prove that checking whether a given DFA A is in FG is co-NP-hard and provide an algorithm for this problem which is exponential in the number of states A. 相似文献
75.
Walter Lang Frank Jakobs Elena Tolstosheeva Hannes Sturm Azat Ibragimov Antonia Kesel Dirk Lehmhus Ursula DickeAuthor vitae 《Sensors and actuators. A, Physical》2011,171(1):3-11
Ubiquitous computing is about to become part of our everyday lives by integrating hundreds of “invisible” to us computing devices in our environment, so that they can unobtrusively and constantly assist us. This will imply more and smaller “invisible” sensors, homogeneously distributed and at the same time densely packed in host materials, responding to various stimuli and immediately delivering information. In order to reach this aim, the embedded sensors should be integrated within the host material, heading towards sensorial materials. The first step is to omit all parts that are not needed for the sensorial task and to find new solutions for a gentle integration. This is what we call function scale integration. The paper discusses sensor embedding in the human hand as an example of integration in nature, new technological applications and main challenges associated with this approach. 相似文献
76.
Because of their widespread use in real-world transportation situations, hub location models have been extensively studied in the last two decades. Many types of hub location problems are NP-hard and remain unmanageable when the number of nodes exceeds 200. We present a way to tackle large-sized problems using aggregation, explore the resulting error, and show how to reduce it. Furthermore, we develop a heuristic based on aggregation for k-hub center problems and present computational results. 相似文献
77.
In this paper we consider the case of nonlinear convection-diffusion problems with a dominating convection term and we propose
exponential integrators based on the composition of exact pure convection flows. These methods can be applied to the numerical
integration of the considered PDEs in a semi-Lagrangian fashion. Semi-Lagrangian methods perform well on convection dominated
problems (Pironneau in Numer. Math. 38:309–332, 1982; Hockney and Eastwood in Computer simulations using particles. McGraw-Hill, New York, 1981; Rees and Morton in SIAM J. Sci. Stat. Comput. 12(3):547–572, 1991; Baines in Moving finite elements. Monographs on numerical analysis. Clarendon Press, Oxford, 1994).
In these methods linear convective terms can be integrated exactly by first computing the characteristics corresponding to the gridpoints of the adopted discretization, and then producing
the numerical approximation via an interpolation procedure. 相似文献
78.
Ciprian Iliescu Guolin Xu Elena Barbarini Marioara Avram Andrei Avram 《Microsystem Technologies》2009,15(8):1157-1162
This paper presents a microfluidic device for magnetophoretic separation of red blood cells from blood under continuous flow.
The separation method consists of continuous flow of a blood sample (diluted in PBS) through a microfluidic channel which
presents on the bottom “dots” of ferromagnetic layer. By applying a magnetic field perpendicular on the flowing direction,
the ferromagnetic “dots” generate a gradient of magnetic field which amplifies the magnetic force. As a result, the red blood
cells are captured on the bottom of the microfluidic channel while the rest of the blood is collected at the outlet. Experimental
results show that an average of 95% of red blood cells is trapped in the device. 相似文献
79.
Maria-Iuliana Dascalu Constanta-Nicoleta Bodea Monica Nastasia Mihailescu Elena Alice Tanase Patricia Ordoñez de Pablos 《Behaviour & Information Technology》2016,35(4):290-297
The almost unlimited access to educational information plethora came with a drawback: finding meaningful material is not a straightforward task anymore. Recommender algorithms can be used to make smart decisions in complex information systems and help the users decide upon useful materials; therefore, they become a promising area in academia and industry. The current paper presents a survey on educational recommender systems (RS): a set of analysis criteria are exposed and the technological specifications and challenges of each analysed system are provided, in the context of the main trends in the development of RS. Also, an ontology-based educational recommendation mechanism is proposed and its application to lifelong learning is highlighted, proving that RS can successfully support new learning paradigms. 相似文献
80.