全文获取类型
收费全文 | 757篇 |
免费 | 20篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 151篇 |
金属工艺 | 7篇 |
机械仪表 | 12篇 |
建筑科学 | 22篇 |
能源动力 | 24篇 |
轻工业 | 60篇 |
水利工程 | 8篇 |
无线电 | 99篇 |
一般工业技术 | 90篇 |
冶金工业 | 12篇 |
原子能技术 | 5篇 |
自动化技术 | 285篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 21篇 |
2021年 | 19篇 |
2020年 | 12篇 |
2019年 | 12篇 |
2018年 | 15篇 |
2017年 | 17篇 |
2016年 | 23篇 |
2015年 | 27篇 |
2014年 | 30篇 |
2013年 | 64篇 |
2012年 | 54篇 |
2011年 | 55篇 |
2010年 | 42篇 |
2009年 | 59篇 |
2008年 | 50篇 |
2007年 | 50篇 |
2006年 | 42篇 |
2005年 | 30篇 |
2004年 | 23篇 |
2003年 | 18篇 |
2002年 | 15篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 9篇 |
1998年 | 9篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1970年 | 1篇 |
1965年 | 1篇 |
1958年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有778条查询结果,搜索用时 15 毫秒
1.
2.
Performance analysis of IEEE 802.11 ad hoc networks in the presence of exposed terminals 总被引:1,自引:0,他引:1
The paper evaluates the performance effects of exposed terminals in IEEE 802.11 ad hoc networks in finite load conditions. It derives analytical models for the estimation of channel utilization and media access delay for IEEE 802.11 ad hoc networks in finite load conditions with and without exposed terminals. The simulation results show that the analytical estimated channel utilization and media access delay metrics are fairly accurate. 相似文献
3.
Argyris G. Kagiannas Thanassis Didis Dimitris Th. Askounis John Psarras 《国际能源研究杂志》2003,27(2):173-186
The needs that an energy supply system must meet are constantly changing, due to technological, social and political reasons. Effective energy planning is a dynamic process that is repeated periodically and adjusts to changing conditions. Energy decision makers and planners are no longer able to rely on inductive decision making since they have to investigate the effect of various decision parameters and possible future changes. To help in this process, models have been developed where estimates of future load growth, candidate power plants, fuels and other key factors can be introduced, from which the planners can evaluate decision parameters and the available alternatives. The paper presents the different methodologies and practices that are used by 11 energy models for energy demand forecasting, supply side management and generation expansion planning, demand side management and integrated resource planning. The paper concludes to the presentation of a strategic appraisal of the examined energy models appropriate for energy planning in Mozambique. Three models are proposed for conducting demand forecasting, generation expansion planning and demand side management. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
4.
Gabriel Tsechpenakis Dimitris Metaxas Carol Neidle 《Computer Vision and Image Understanding》2006,104(2-3):140
We present a data-driven dynamic coupling between discrete and continuous methods for tracking objects of high dofs, which overcomes the limitations of previous techniques. In our approach, two trackers work in parallel, and the coupling between them is based on the tracking error. We use a model-based continuous method to achieve accurate results and, in cases of failure, we re-initialize the model using our discrete tracker. This method maintains the accuracy of a more tightly coupled system, while increasing its efficiency. At any given frame, our discrete tracker uses the current and several previous frames to search into a database for the best matching solution. For improved robustness, object configuration sequences, rather than single configurations, are stored in the database. We apply our framework to the problem of 3D hand tracking from image sequences and the discrimination between fingerspelling and continuous signs in American Sign Language. 相似文献
5.
Dimitris G. Kapopoulos Michael Hatzopoulos Panagiotis Stamatopoulos 《Journal of Intelligent Information Systems》2002,19(1):111-134
Although computer speed has steadily increased and memory is getting cheaper, the need for storage managers to deal efficiently with applications that cannot be held into main memory is vital. Dealing with large quantities of clauses implies the use of persistent knowledge and thus, indexing methods are essential to access efficiently the subset of clauses relevant to answering a query. We introduce PerKMan, a storage manager that uses G-trees, and aims at efficient manipulation of large amounts of persistent knowledge. PerKMan may be connected to Prolog systems that offer an external C language interface. As well as the fact that the storage manager allows different arguments of a predicate to share a common index dimension in a novel manner, it indexes rules and facts in the same manner. PerKMan handles compound terms efficiently and its data structures adapt their shape to large dynamic volumes of clauses, no matter what the distribution. The storage manager achieves fast clause retrieval and reasonable use of disk space. 相似文献
6.
This work introduces decentralized query processing techniques based on MIDAS, a novel distributed multidimensional index. In particular, MIDAS implements a distributed k-d tree, where leaves correspond to peers, and internal nodes dictate message routing. MIDAS requires that peers maintain little network information, and features mechanisms that support fault tolerance and load balancing. The proposed algorithms process point and range queries over the multidimensional indexed space in only O(log n) hops in expectance, where n is the network size. For nearest neighbor queries, two processing alternatives are discussed. The first, termed eager processing, has low latency (expected value of O(log n) hops) but may involve a large number of peers. The second, termed iterative processing, has higher latency (expected value of O(log2 n) hops) but involves far fewer peers. A detailed experimental evaluation demonstrates that our query processing techniques outperform existing methods for settings involving real spatial data as well as in the case of high dimensional synthetic data. 相似文献
7.
On the Competitive Ratio for Online Facility Location 总被引:2,自引:0,他引:2
Dimitris Fotakis 《Algorithmica》2008,50(1):1-57
We consider the problem of Online Facility Location, where the demand points arrive online and must be assigned irrevocably
to an open facility upon arrival. The objective is to minimize the sum of facility and assignment costs. We prove that the
competitive ratio for Online Facility Location is Θ
. On the negative side, we show that no randomized algorithm can achieve a competitive ratio better than Ω
against an oblivious adversary even if the demands lie on a line segment. On the positive side, we present a deterministic
algorithm which achieves a competitive ratio of
in every metric space.
A preliminary version of this work appeared in the Proceedings of the 30th International Colloquium on Automata, Languages
and Programming (ICALP 2003), Lecture Notes in Computer Science 2719. This work was done while the author was at the Max-Planck-Institut
für Informatik, Saarbrücken, Germany, and was partially supported by the Future and Emerging Technologies programme of the
EU under contract number IST-1999-14186 (ALCOM–FT). 相似文献
8.
On the information modeling for the electronic operation of supply chains: A maritime case study 总被引:1,自引:0,他引:1
Nowadays, the manufacturing industry is adopting modern information technologies in order to optimize their business process and to achieve integration with supply chain partners that are geographically dispersed, by expanding the physical limits of their business globally. The growth of the World Wide Web and the advantages of the software technologies arising from it render this goal possible. This paper discusses how modern information technology, particularly the ISO 10303—STEP and eXtensible Markup Language—XML, can be utilized jointly to support the communication of different partners. An approach to support enterprise operation through efficient data exchanges, by adopting modern data modeling techniques for integration among partners worldwide and using the web as a communication layer, is described. The paper deals particularly with the ship repair industry as a case study of these problems and suggests a feasible solution. 相似文献
9.
A Survey of Applications of Polyoxometalates 总被引:1,自引:0,他引:1
Katsoulis DE 《Chemical reviews》1998,98(1):359-388
10.
Vafeiadis Thanasis Bora-Senta Efthimia Kugiumtzis Dimitris 《Simulation Modelling Practice and Theory》2011,19(5):1384-1398
We propose a method to detect the onset of linear trend in a time series and estimate the change point T from the profile of a linear trend test statistic, computed on consecutive overlapping time windows along the time series. We compare our method to two standard methods for trend change detection and evaluate them with Monte Carlo simulations for different time series lengths, autocorrelation strengths, trend slopes and distribution of residuals. The proposed method turns out to estimate T better for small and correlated time series. The methods were also applied to global temperature records suggesting different turning points. 相似文献