全文获取类型
收费全文 | 4932篇 |
免费 | 281篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 64篇 |
综合类 | 8篇 |
化学工业 | 953篇 |
金属工艺 | 55篇 |
机械仪表 | 78篇 |
建筑科学 | 187篇 |
矿业工程 | 5篇 |
能源动力 | 165篇 |
轻工业 | 345篇 |
水利工程 | 54篇 |
石油天然气 | 36篇 |
无线电 | 400篇 |
一般工业技术 | 1227篇 |
冶金工业 | 675篇 |
原子能技术 | 15篇 |
自动化技术 | 954篇 |
出版年
2024年 | 13篇 |
2023年 | 60篇 |
2022年 | 98篇 |
2021年 | 143篇 |
2020年 | 118篇 |
2019年 | 124篇 |
2018年 | 127篇 |
2017年 | 141篇 |
2016年 | 168篇 |
2015年 | 137篇 |
2014年 | 197篇 |
2013年 | 344篇 |
2012年 | 320篇 |
2011年 | 399篇 |
2010年 | 305篇 |
2009年 | 288篇 |
2008年 | 316篇 |
2007年 | 249篇 |
2006年 | 224篇 |
2005年 | 189篇 |
2004年 | 156篇 |
2003年 | 141篇 |
2002年 | 133篇 |
2001年 | 66篇 |
2000年 | 63篇 |
1999年 | 64篇 |
1998年 | 66篇 |
1997年 | 61篇 |
1996年 | 53篇 |
1995年 | 54篇 |
1994年 | 44篇 |
1993年 | 42篇 |
1992年 | 38篇 |
1991年 | 21篇 |
1990年 | 27篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 27篇 |
1986年 | 15篇 |
1985年 | 31篇 |
1984年 | 14篇 |
1983年 | 9篇 |
1982年 | 13篇 |
1981年 | 21篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1975年 | 8篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1964年 | 4篇 |
排序方式: 共有5221条查询结果,搜索用时 0 毫秒
51.
Multifocus image fusion is the process of obtaining a single image from multiple partially focused images such that the newly formed image consists of the well-defined information extracted from each source image. This paper proposes the use of saliency of the source images based on Mutual Spectral Residual. Spectral Residual brings out the unique/salient features of an image in frequency domain. The idea of proposed mutual spectral residual is to emphasize the relative unique features of a source image with respect to the other source images. The relative unique features are utilized to form saliency maps for each source image. These saliency maps can clearly indicate the focused and defocused parts of an image. Based on the saliency maps obtained, the image fusion takes place in spatial domain. Visual inspection and quantitative evaluation of the fused images obtained by the proposed method, using different evaluation metrics, demonstrate its effectiveness over several existing image fusion methods. 相似文献
52.
Wenjuan Zhu Anup M. Vader Abhinav Chadda Ming C. Leu Xiaoqing F. Liu Jonathan B. Vance 《Virtual Reality》2013,17(2):125-136
This paper describes the development of a Wii remote (Wiimote)–based low-cost motion capture system and demonstrates its application for automated assembly simulation. Multiple Wiimotes are used to form a vision system to perform motion capture in 3D space. A hybrid algorithm for calibrating a multi-camera stereo vision system has been developed based on Zhang’s and Svoboda’s calibration algorithms. This hybrid algorithm has been evaluated and shown accuracy improvement over Svoboda’s algorithm for motion capture with multiple cameras. The captured motion data are used to automatically generate an assembly simulation of objects represented by CAD models in real time. The Wiimote-based motion capture system is practically attractive because it is inexpensive, wireless, and easily portable. Application examples have been developed for a single vision system with two Wiimotes to track the assembly of a microsatellite prototype frame and for an integrated vision system with four Wiimotes to track the assembly of a bookshelf. 相似文献
53.
Jonathan A. Czuba James L. Best Kevin A. Oberg Daniel R. Parsons P. Ryan Jackson Marcelo H. Garcia Peter Ashmore 《Journal of Great Lakes research》2011,37(3):480-493
An integrated multibeam echo sounder and acoustic Doppler current profiler field survey was conducted in July 2008 to investigate the morphodynamics of the St. Clair River at the outlet of Lake Huron. The principal morphological features of the upper St. Clair River included flow-transverse bedforms that appear weakly mobile, erosive bedforms in cohesive muds, thin non-cohesive veneers of weakly mobile sediment that cover an underlying cohesive (till or glacio-lacustrine) surface, and vegetation that covers the bed. The flow was characterized by acceleration as the banks constrict from Lake Huron into the St. Clair River, an approximately 1500-m long region of flow separation downstream from the Blue Water Bridge, and secondary flow connected to: i) channel curvature; ii) forcing of the flow by local bed topography, and iii) flow wakes in the lee side of ship wrecks. Nearshore, sand-sized, sediment from Lake Huron was capable of being transported into, and principally along, the banks of the upper St. Clair River by the measured flow. A comparison of bathymetric surveys conducted in 2007 and 2008 identifies that the gravel bed does undergo slow downstream movement, but that this movement does not appear to be generated by the mean flow, and could possibly be caused by ship-propeller-induced turbulence. The study results suggest that the measured mean flow and dredging within the channel have not produced major scour of the upper St. Clair River and that the recent fall in the level of Lake Huron is unlikely to have been caused by these mechanisms. 相似文献
54.
Boris S. Mitavskiy Elio Tuci Chris Cannings Jonathan Rowe Jun He 《Natural computing》2013,12(4):473-484
The classical Geiringer theorem addresses the limiting frequency of occurrence of various alleles after repeated application of crossover. It has been adopted to the setting of evolutionary algorithms and, a lot more recently, reinforcement learning and Monte-Carlo tree search methodology to cope with a rather challenging question of action evaluation at the chance nodes. The theorem motivates novel dynamic parallel algorithms that are explicitly described in the current paper for the first time. The algorithms involve independent agents traversing a dynamically constructed directed graph that possibly has loops and multiple edges. A rather elegant and profound category-theoretic model of cognition in biological neural networks developed by a well-known French mathematician, professor Andree Ehresmann jointly with a neurosurgeon, Jan Paul Vanbremeersch over the last thirty years provides a hint at the connection between such algorithms and Hebbian learning. 相似文献
55.
Barbara Yersin Jonathan Maïm Fiorenzo Morini Daniel Thalmann 《The Visual computer》2008,24(10):859-870
Real-time crowd motion planning requires fast, realistic methods for path planning as well as obstacle avoidance. In a previous
work (Morini et al. in Cyberworlds International Conference, pp. 144–151, 2007), we introduced a hybrid architecture to handle real-time motion planning of thousands of pedestrians. In this article, we
present an extended version of our architecture, introducing two new features: an improved short-term collision avoidance
algorithm, and simple efficient group behavior for crowds. Our approach allows the use of several motion planning algorithms
of different precision for regions of varied interest. Pedestrian motion continuity is ensured when switching between such
algorithms. To assess our architecture, several performance tests have been conducted, as well as a subjective test demonstrating
the impact of using groups. Our results show that the architecture can plan motion in real time for several thousands of characters.
相似文献
Daniel ThalmannEmail: |
56.
Differencing and merging of architectural views 总被引:1,自引:0,他引:1
Marwan Abi-Antoun Jonathan Aldrich Nagi Nahas Bradley Schmerl David Garlan 《Automated Software Engineering》2008,15(1):35-74
Differencing and merging architectural views is an important activity in software engineering. However, existing approaches
are still based on restrictive assumptions, such as requiring view elements to have unique identifiers or exactly matching
types, which is often not the case in many application domains.
We propose an approach based on structural information. We generalize a published polynomial-time tree-to-tree correction
algorithm that detects inserts, renames and deletes, into a novel algorithm that additionally detects restricted moves. Our
algorithm also supports forcing and preventing matches between view elements.
We incorporate the algorithm into tools to compare and merge Component-and-Connector (C&C) architectural views. We provide
an empirical evaluation of the algorithm. We illustrate the tools using extended examples, and use them to detect and reconcile
interesting differences between real architectural views.
This article is an expanded version of the following paper: Abi-Antoun, M., Aldrich, J., Nahas, N., Schmerl, B., and Garlan, D:
2006, ‘Differencing and Merging of Architectural Views’. In: Proceedings of the 21st IEEE International Conference on Automated Software Engineering, pp. 47–58. 相似文献
57.
Correlation between a dithering signal and the prediction error has been used for detecting model mismatch in univariate model based control systems. This paper extends that approach to MIMO control systems. A closed-loop cross-correlation method is presented to detect which specific input-output pairings of a model-based controller are mismatched. This method may be used in screening the complete set of models and in selecting candidate models for re-identification. The method first finds the rows and columns of the transfer function matrix that contain mismatch, and then the candidates are found by the intersection of the said rows and columns. Placing the system under partial control, whereby one or more of the manipulated variables are held constant, can be used to further reduce the set of candidate models. 相似文献
58.
Rivilis I Van Eerd D Cullen K Cole DC Irvin E Tyson J Mahood Q 《Applied ergonomics》2008,39(3):342-358
The objective of this study was to conduct a systematic review of the literature on the effectiveness of participatory ergonomic (PE) interventions for improving workers' health. The search strategy targeted six electronic databases and identified 442 potential articles. Each article was examined by pairs of reviewers for relevance (assessed a participative ergonomic workplace intervention, with at least one health outcome, published in English in peer reviewed literature). Twenty-three articles met relevance criteria and were then appraised for methodological strength. Using a best evidence synthesis approach, 12 studies that were rated as 'medium' or higher provided partial to moderate evidence that PE interventions have a positive impact on: musculoskeletal symptoms, reducing injuries and workers' compensation claims, and a reduction in lost days from work or sickness absence. However, the magnitude of the effect requires more precise definition. 相似文献
59.
The measured photocurrents from two different p-n-junction silicon photodiodes at 170-? (73-eV) and at 8.34-? (1480-eV) light are presented. One is a standard extreme-UV photodiode fabricated on low resistivity silicon (70-100 Ω cm), and the other is fabricated on high-resistivity silicon (> 2 × 10(4) Ω cm). The photocurrents from the diode on high-resistivity silicon are at least an order of magnitude greater than the photocurrents from the diode on low-resistivity silicon when a reverse bias of 40 V is applied to each. This photocurrent enhancement is 15.4 ± 4 at 8.34 ? and 12.5 ± 2 at 170 ?. 相似文献
60.
Nicholas F. Dudley Ward Jonathan R. Partington 《Mathematics of Control, Signals, and Systems (MCSS)》1995,8(3):257-278
The model approximation of transfer functions using rational wavelets (or molecular decompositions) is considered. By using techniques from Hardy-Sobolev spaces it is shown that Hilbert space methods such as a modified matching-pursuit algorithm and least-squares technique can be employed to obtain good approximations in bothH
2 andH
norms. Several theoretical results are given on rates of convergence when the methods are applied to delay systems and fractional filters.The research of the first author was supported by E.P.S.R.C. 相似文献