全文获取类型
收费全文 | 462243篇 |
免费 | 10190篇 |
国内免费 | 3996篇 |
专业分类
电工技术 | 10786篇 |
技术理论 | 6篇 |
综合类 | 4394篇 |
化学工业 | 69345篇 |
金属工艺 | 20168篇 |
机械仪表 | 17251篇 |
建筑科学 | 12948篇 |
矿业工程 | 4318篇 |
能源动力 | 13447篇 |
轻工业 | 31788篇 |
水利工程 | 5304篇 |
石油天然气 | 12355篇 |
武器工业 | 474篇 |
无线电 | 55459篇 |
一般工业技术 | 89810篇 |
冶金工业 | 78126篇 |
原子能技术 | 9887篇 |
自动化技术 | 40563篇 |
出版年
2022年 | 3607篇 |
2021年 | 6172篇 |
2020年 | 4703篇 |
2019年 | 5380篇 |
2018年 | 8243篇 |
2017年 | 8448篇 |
2016年 | 8675篇 |
2015年 | 6618篇 |
2014年 | 10080篇 |
2013年 | 23391篇 |
2012年 | 14996篇 |
2011年 | 19202篇 |
2010年 | 15768篇 |
2009年 | 16941篇 |
2008年 | 17236篇 |
2007年 | 16962篇 |
2006年 | 15555篇 |
2005年 | 13844篇 |
2004年 | 12496篇 |
2003年 | 12513篇 |
2002年 | 12288篇 |
2001年 | 11781篇 |
2000年 | 10702篇 |
1999年 | 11190篇 |
1998年 | 25520篇 |
1997年 | 17735篇 |
1996年 | 13865篇 |
1995年 | 10340篇 |
1994年 | 8973篇 |
1993年 | 8837篇 |
1992年 | 6406篇 |
1991年 | 5957篇 |
1990年 | 5880篇 |
1989年 | 5481篇 |
1988年 | 5191篇 |
1987年 | 4504篇 |
1986年 | 4366篇 |
1985年 | 4847篇 |
1984年 | 4449篇 |
1983年 | 4017篇 |
1982年 | 3677篇 |
1981年 | 3741篇 |
1980年 | 3448篇 |
1979年 | 3330篇 |
1978年 | 3336篇 |
1977年 | 3751篇 |
1976年 | 4847篇 |
1975年 | 2850篇 |
1974年 | 2638篇 |
1973年 | 2705篇 |
排序方式: 共有10000条查询结果,搜索用时 163 毫秒
61.
The Fe/C/SiCN composite ceramics were synthesized by polymer-derived method to obtain the integration of structure and functions. The electromagnetic waves (EMW) absorption properties at X and Ku bands were investigated. The addition of nano-sized Fe particles improved the magnetic loss and impedance matching, and the carbon nanotubes generated by the iron in-situ catalysis increased the internal relaxation polarization and interfacial polarization, which together improved the EMW absorption properties significantly. In particular, the Fe/C/SiCN-9 showed the optimum reflection loss (RL) of ?31.06 dB at 10.03 GHz with an effective absorption bandwidth (EAB, RL < ?10 dB) of 3.03 GHz at 2.51 mm, indicating the excellent EMW absorption properties of Fe/C/SiCN composite ceramics. 相似文献
62.
Klimis?S.?NtalianisEmail author Anastasios?D.?Doulamis Nikolaos?D.?Doulamis Nikos?E.?Mastorakis Athanasios?S.?Drigas 《Journal of Signal Processing Systems》2015,80(2):153-161
In this paper, we present a novel memory access reduction scheme (MARS) for two-dimension fast cosine transform (2-D FCT). It targets programmable DSPs with high memory-access latency. It reduces the number of memory accesses by: 1) reducing the number of weighting factors and 2) combining butterflies in vector-radix 2-D FCT pruning diagram from two stages to one stage with an efficient structure. Hardware platform based on general purpose processor is used to verify the effectiveness of the proposed method for vector-radix 2-D FCT pruning implementation. Experimental results validate the benefits of the proposed method with reduced memory access, less clock cycle and fewer memory space compared with the conventional implementation. 相似文献
63.
64.
65.
With the emergence of large-scale knowledge base, how to use triple information to generate natural questions is a key technology in question answering systems. The traditional way of generating questions require a lot of manual intervention and produce lots of noise. To solve these problems, we propose a joint model based on semi-automated model and End-to-End neural network to automatically generate questions. The semi-automated model can generate question templates and real questions combining the knowledge base and center graph. The End-to-End neural network directly sends the knowledge base and real questions to BiLSTM network. Meanwhile, the attention mechanism is utilized in the decoding layer, which makes the triples and generated questions more relevant. Finally, the experimental results on SimpleQuestions demonstrate the effectiveness of the proposed approach. 相似文献
66.
67.
68.
Fermanelli Carla S. Galarza Emilce D. Pierella Liliana B. Renzini María S. Saux Clara 《Topics in Catalysis》2019,62(12-16):918-930
Topics in Catalysis - In this work, a simple thermal-catalytic system was used to valorize peanut shells (Arachis hypogaea), the residual biomass from the peanut industry. To accomplish this... 相似文献
69.
Gomes A. C. S. A. Costa L. C. Brito D. C. Frana R. J. Marques Mnica R. C. 《Polymer Bulletin》2020,77(4):1969-1981
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with... 相似文献
70.
Bankov S. E. Vesnik M. V. Kravchenko V. F. 《Journal of Communications Technology and Electronics》2020,65(4):398-405
Journal of Communications Technology and Electronics - Abstract—The article presents a rigorous numerical solution, using the Wiener–Hopf method, to the problem of plane wave... 相似文献