全文获取类型
收费全文 | 642840篇 |
免费 | 37435篇 |
国内免费 | 21253篇 |
专业分类
电工技术 | 30508篇 |
技术理论 | 48篇 |
综合类 | 31876篇 |
化学工业 | 103753篇 |
金属工艺 | 34809篇 |
机械仪表 | 33394篇 |
建筑科学 | 38788篇 |
矿业工程 | 14883篇 |
能源动力 | 17545篇 |
轻工业 | 49995篇 |
水利工程 | 10539篇 |
石油天然气 | 30953篇 |
武器工业 | 3627篇 |
无线电 | 70103篇 |
一般工业技术 | 87652篇 |
冶金工业 | 61014篇 |
原子能技术 | 9414篇 |
自动化技术 | 72627篇 |
出版年
2024年 | 1870篇 |
2023年 | 7031篇 |
2022年 | 13214篇 |
2021年 | 18543篇 |
2020年 | 13857篇 |
2019年 | 11896篇 |
2018年 | 14499篇 |
2017年 | 15981篇 |
2016年 | 15037篇 |
2015年 | 19033篇 |
2014年 | 24795篇 |
2013年 | 35354篇 |
2012年 | 33911篇 |
2011年 | 38980篇 |
2010年 | 33809篇 |
2009年 | 33536篇 |
2008年 | 32998篇 |
2007年 | 31761篇 |
2006年 | 30640篇 |
2005年 | 26914篇 |
2004年 | 19996篇 |
2003年 | 17918篇 |
2002年 | 17065篇 |
2001年 | 15623篇 |
2000年 | 14759篇 |
1999年 | 15353篇 |
1998年 | 20170篇 |
1997年 | 15586篇 |
1996年 | 13280篇 |
1995年 | 10365篇 |
1994年 | 8520篇 |
1993年 | 7145篇 |
1992年 | 5372篇 |
1991年 | 4773篇 |
1990年 | 4241篇 |
1989年 | 3949篇 |
1988年 | 3602篇 |
1987年 | 3050篇 |
1986年 | 2852篇 |
1985年 | 2976篇 |
1984年 | 2698篇 |
1983年 | 2467篇 |
1982年 | 2294篇 |
1981年 | 2305篇 |
1980年 | 2234篇 |
1979年 | 2169篇 |
1978年 | 2066篇 |
1977年 | 2518篇 |
1976年 | 3307篇 |
1973年 | 1891篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Wei Hui 《Frontiers of Computer Science in China》2007,1(3):361-372
Almost all applications of Artificial Neural Networks (ANNs) depend mainly on their memory ability. The characteristics of
typical ANN models are fixed connections, with evolved weights, globalized representations, and globalized optimizations,
all based on a mathematical approach. This makes those models to be deficient in robustness, efficiency of learning, capacity,
anti-jamming between training sets, and correlativity of samples, etc. In this paper, we attempt to address these problems
by adopting the characteristics of biological neurons in morphology and signal processing. A hierarchical neural network was
designed and realized to implement structure learning and representations based on connected structures. The basic characteristics
of this model are localized and random connections, field limitations of neuron fan-in and fan-out, dynamic behavior of neurons,
and samples represented through different sub-circuits of neurons specialized into different response patterns. At the end
of this paper, some important aspects of error correction, capacity, learning efficiency, and soundness of structural representation
are analyzed theoretically. This paper has demonstrated the feasibility and advantages of structure learning and representation.
This model can serve as a fundamental element of cognitive systems such as perception and associative memory. 相似文献
992.
993.
A synthesis procedure for generating current conveyor active filters is presented, and a novel network which realises the general 2nd-order voltage transfer function is given.<> 相似文献
994.
995.
996.
997.
Blair J.D. Correale A. Jr. Cranford H.C. Dombrowski D.A. Erdelyi C.K. Hoffman C.R. Lamphere J.L. Lang K.W. Lee J.K. Mullen J.M. Norman V.R. Oakland S.F. 《Solid-State Circuits, IEEE Journal of》1989,24(6):1647-1655
The authors describe a 9.02×9.02-mm chip built in 1-μm CMOS with two levels of metal and an additional mask level for fabricating capacitors. It contains both analog and digital circuits and has provisions for self-test. The function includes the transmitter, receiver, protocol handler, an microprocessor, as well as interfaces for RAM/ROM storage, IBM PC bus, IBM PS/2 bus, IBM 3174 bus, and Motorola 68000 bus. The physical design terrains are formed by 24K circuits of standard cell gates, a 10K-circuit equivalent hand-honed custom microprocessor, and an analog macro. The chip operates from a single 5-V supply, and the power consumption is 0.8 W nominal at 16 Mb/s. The chip can also be operated at 4 Mb/s 相似文献
998.
999.
To reduce the receiver complexity of the space-time bit-interleaved coded modulation (ST-BICM) scheme, this letter describes a turbo-type iterative structure consisting of a modified Gaussian approximation (MGA) detector and an a posteriori probability (APP) decoder. Utilizing the characteristics of the interleaving and the central limited theoretic, the MGA detector first assumes the superposition of the transmitted signals as a Gaussian random variable. Then, P most significant signal combinations are identified to calculate the log-likelihood ratio of each bit. Without any pre-process on the received signals, the proposed method is free of matrix inverse operation and can be applied in systems with more transmit antennas than receive antennas. Furthermore, the performance of the MGA approaches that of the optimal detection 相似文献