全文获取类型
收费全文 | 178974篇 |
免费 | 10967篇 |
国内免费 | 5968篇 |
专业分类
电工技术 | 8204篇 |
技术理论 | 3篇 |
综合类 | 10062篇 |
化学工业 | 25976篇 |
金属工艺 | 10209篇 |
机械仪表 | 9307篇 |
建筑科学 | 9852篇 |
矿业工程 | 3583篇 |
能源动力 | 3631篇 |
轻工业 | 12519篇 |
水利工程 | 3536篇 |
石油天然气 | 4428篇 |
武器工业 | 1048篇 |
无线电 | 20241篇 |
一般工业技术 | 26403篇 |
冶金工业 | 6532篇 |
原子能技术 | 1616篇 |
自动化技术 | 38759篇 |
出版年
2024年 | 590篇 |
2023年 | 1881篇 |
2022年 | 3813篇 |
2021年 | 4793篇 |
2020年 | 3657篇 |
2019年 | 2824篇 |
2018年 | 17282篇 |
2017年 | 16680篇 |
2016年 | 12798篇 |
2015年 | 4952篇 |
2014年 | 5898篇 |
2013年 | 6609篇 |
2012年 | 10394篇 |
2011年 | 16769篇 |
2010年 | 15050篇 |
2009年 | 11898篇 |
2008年 | 12971篇 |
2007年 | 13623篇 |
2006年 | 5451篇 |
2005年 | 5511篇 |
2004年 | 4123篇 |
2003年 | 3559篇 |
2002年 | 2764篇 |
2001年 | 1951篇 |
2000年 | 1945篇 |
1999年 | 1604篇 |
1998年 | 1072篇 |
1997年 | 933篇 |
1996年 | 849篇 |
1995年 | 699篇 |
1994年 | 520篇 |
1993年 | 400篇 |
1992年 | 344篇 |
1991年 | 253篇 |
1990年 | 178篇 |
1989年 | 176篇 |
1988年 | 138篇 |
1987年 | 71篇 |
1986年 | 48篇 |
1985年 | 42篇 |
1984年 | 35篇 |
1968年 | 43篇 |
1966年 | 42篇 |
1965年 | 45篇 |
1959年 | 43篇 |
1958年 | 37篇 |
1957年 | 36篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Improving signal prediction performance of neural networks through multiresolution learning approach. 总被引:1,自引:0,他引:1
Yao Liang Xu Liang 《IEEE transactions on systems, man, and cybernetics. Part B, Cybernetics》2006,36(2):341-352
In this paper, we extend the original work on multiresolution learning for neural networks, and present new developments on the multiresolution learning paradigm. The contributions of this paper include: (1) proposing a new concept and method of adjustable neural activation functions in multiresolution learning to improve neural network learning efficacy and generalization performance for signal predictions; (2) providing new insightful explanations for the multiresolution learning paradigm from a multiresolution optimization perspective; (3) exploring underlying ideas why the multiresolution learning scheme associated with adjustable activation functions would be more appropriate for the multiresolution learning paradigm; and (4) providing rigorous validations to evaluate the multiresolution learning paradigm with adjustable activation functions and comparing it with the schemes of multiresolution learning with fixed activation functions and traditional learning. This paper presents systematically new analytical and experimental results on the multiresolution learning approach for training an individual neural network model, demonstrates our integral solution on neural network learning efficacy, and illustrates the significant improvements on neural networks' generalization performance and robustness for nonlinear signal predictions. 相似文献
22.
Construction of one of the largest petrochemical joint venture projects in the country - and BP 's largest project in China - kicked off in the Shanghai Chemical Industrial Park in late-March, 2002.The developer of the project is the Shanghai SECCO Petrochemical Co. Ltd, a 50-30-20 equityjoint venture by BP, China Petrochemical Corporation (Sinopec) and the Shanghai Petrochemical Co. Ltd (SPC). This project is slated for completion and opening in the first half on 2005, with a tota… 相似文献
23.
Less may not be more,but it still counts: The state of social capital in Yeoville,Johannesburg 总被引:2,自引:2,他引:0
Kirsten Harrison 《Urban Forum》2002,13(1):67-84
24.
25.
A kind of complex additive mainly containing Al, Mg, F, and O was prepared. The synthetical performances of the property-modified prebaked anodes containing additives were tested in laboratory. On the basis of ideal testing results obtained, a large number of industrial prebaked property-modified anodes are prepared in a large-scale aluminum company. Further more, they are all used in 160 kA prebaked anode aluminum electrolysis cells. The statistic result show that, compared with common anodes, the property-modified ones enhance current by 11.6 kg per ton aluminum averagely. 相似文献
26.
Yanqiu Shao Jiqing Han Ting Liu Yongzhen Zhao 《International Journal of Speech Technology》2007,10(1):45-55
In real speech, not like lexical words (LWs), prosodic words (PWs) are basic rhythmic units. The naturalness of a Text-to-Speech
(TTS) system is directly influenced by the segmentation of the PWs. Most of the PWs are the combination of several LWs. In
this paper, three Lexical Combination Models are proposed to combine LWs into PWs, including a Directed Acyclic Graph Model,
a Segmentation Model and a Markov Model (MM). To cope with the situation where some long LWs should be segmented into two
or more PWs, a Lexical Split Model (LSM) is applied to the long LWs. Experimental results prove that relatively constant results
with various training data can be obtained from a MM. The Transformation-Based Error Driven Learning (TBED) algorithm, for
its high performance of individual property, is applied in combination with the MM to improve the precision of PW segmentation.
Experiments show that among the three proposed models, the MM combined with TBED and LSM, leads to the best performance, in
which a precision of 93.00% and a recall of 93.23% are achieved. The perception test indicates that by using PWs as the lowest
prosodic units a speech sounds more natural and acceptable than by using LWs.
This paper is supported by NSFC Project (60503071); 973 Natural Basic Research Program of China (2004CB318102); Postdoctor
Science Foundation of P. R. China (20070420275). 相似文献
27.
In this paper we describe, from a theoretical point of view, critical configurations for the projective reconstruction of
a set of points, for a single view, i.e. for calibration of a camera, in the case of projections from ℙk to ℙ2 for k ≥ 4. We give first a general result describing these critical loci in ℙk, which, if irreducible, are algebraic varieties of dimension k−2 and degree 3. If k=4 they can be either a smooth ruled surface or a cone and if k = 5 they can be a smooth three dimensional variety, ruled in planes, or a cone. If k≥ 6, the variety is always a cone, the
vertex of which has dimension at least k − 6. The reducible cases are studied in Appendix A.
These results are then applied to determine explicitly the critical loci for the projections from ℙk which arise from the dynamic scenes in ℙ3 considered in [13].
Marina Bertolini is currently Associate Professor of Geometry at the Department of Mathematics at the Università degli Studi di Milano, Italy.
Her main field of research is Complex Projective Algebraic Geometry, with particular interest for the classification of projective
varieties and for the geometry of Grassmann varieties. On these topics M. Bertolini has published more than twenty reviewed
papers on national and international journals. She has been for some years now interested also in applications of Algebraic
Geometry to Computer Vision problems.
Cristina Turrini is Associate Professor of Geometry at the Department of Mathematics of Università degli Studi di Milano, Italy. Her main
research interest is Complex Projective Algebraic Geometry: subvarieties of Grassmannians, special varieties, automorphisms,
classification. In the last two years she has started to work on applications of Algebraic Geometry to problems of Computer
Vision. She is author or co-author of about thirty reviewed papers. She is also involved in popularization of Mathematics,
and on this subject she is co-editor of some books. 相似文献
28.
Xiangfei Chen Jianping Yao Fei Zeng Zhichao Deng 《Photonics Technology Letters, IEEE》2005,17(7):1390-1392
A novel single-longitudinal-mode (SLM) fiber ring laser that incorporates an equivalent phase-shifted fiber Bragg grating acting as an ultra-narrow bandpass filter in the laser cavity is proposed. The equivalent phase-shifted fiber Bragg grating has an ultra-narrow transmission bandwidth which ensures an SLM lasing. Stable SLM operation without mode hopping is demonstrated. 相似文献
29.
30.
Jon T. Carter Paul E. Krajewski Ravi Verma 《JOM Journal of the Minerals, Metals and Materials Society》2008,60(11):77-81
The hot blow forming of magnesium sheet offers significant opportunity for forming complex, lightweight parts for automotive
applications. This paper characterizes the elevated-temperature formability of AZ31 magnesium sheet materials and the effect
of processing conditions on the performance of these materials. In addition, magnesium sheet application development at General
Motors Corporation is reviewed. 相似文献