全文获取类型
收费全文 | 1550篇 |
免费 | 359篇 |
国内免费 | 70篇 |
专业分类
电工技术 | 129篇 |
综合类 | 190篇 |
化学工业 | 3篇 |
金属工艺 | 6篇 |
机械仪表 | 29篇 |
建筑科学 | 4篇 |
矿业工程 | 2篇 |
能源动力 | 3篇 |
轻工业 | 4篇 |
水利工程 | 1篇 |
石油天然气 | 5篇 |
武器工业 | 41篇 |
无线电 | 1163篇 |
一般工业技术 | 46篇 |
冶金工业 | 1篇 |
原子能技术 | 8篇 |
自动化技术 | 344篇 |
出版年
2024年 | 5篇 |
2023年 | 21篇 |
2022年 | 23篇 |
2021年 | 20篇 |
2020年 | 57篇 |
2019年 | 56篇 |
2018年 | 44篇 |
2017年 | 67篇 |
2016年 | 66篇 |
2015年 | 87篇 |
2014年 | 94篇 |
2013年 | 153篇 |
2012年 | 159篇 |
2011年 | 173篇 |
2010年 | 110篇 |
2009年 | 89篇 |
2008年 | 100篇 |
2007年 | 118篇 |
2006年 | 102篇 |
2005年 | 77篇 |
2004年 | 67篇 |
2003年 | 75篇 |
2002年 | 38篇 |
2001年 | 38篇 |
2000年 | 22篇 |
1999年 | 14篇 |
1998年 | 22篇 |
1997年 | 16篇 |
1996年 | 14篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
排序方式: 共有1979条查询结果,搜索用时 321 毫秒
1.
This article proposes an active balancer, which features bidirectional charge shuttling and adaptive equalization current control, to fast counterbalance the state of charge (SOC) of cells in a lithium-ion battery (LIB) string. The power circuit consists of certain bidirectional buck-boost converters to transfer energy among the different cells back and forth. Owing to the characterization of the open-circuit voltage (OCV) vs SOC in LIB being relatively smooth near the SOC middle range, the SOC-inspected balance strategy can achieve more precise and efficient equilibrium than the voltage-based control. Accordingly, a compensated OCV-based SOC estimation is put forward to take into account the discrepancy of SOC estimation. Besides, the varied-duty-cycle (VDC) and curve-fitting modulation (CFM) methods are devised herein to tackle the problems of slow equalization rate and low balance efficacy, which arise from the diminution in balancing current as the SOC difference between the cells decreases in the later duration of equalization especially. The proposed strategies have taken the battery nonlinear characteristic and circuit parameter nonideality into account and can adaptively modulate the duty cycle with the SOC difference to keep balancing current constant throughout the balancing cycle. Simulated and experimental results are given to demonstrate the feasibility and effectiveness of the same prototype constructed. Compared with the fixed duty cycle and the VDC methods, the proposed CFM has the best balancing efficiency of 81.4%, and the balance time is shortened by 27.1% and 18.6%, respectively. 相似文献
2.
微带型Wilkinson功分器设计与实现 总被引:2,自引:0,他引:2
小型低功耗器件是射频电路设计的研究热点,而微带技术具有小型化低功耗的优点,为此在介绍微带型Wilkin-son功分器工作原理的基础上,使用基于矩量法的ADS软件设计、仿真和优化计算相关数据参数,并制作了一个微带功分器实例,最后对加工的样品进行实测,获得与仿真值吻合较好的预期结果。 相似文献
3.
4.
5.
不等波纹函数低通原型的理论及应用 总被引:3,自引:0,他引:3
本文提出不等波纹函数低通原型,并对其理论进行初步探讨。切比雪夫函数及最平坦型巴特活兹函数皆为其特例。文中给出不等波纹函数的几个性质,最后给出两个应用实例,消除耦合环自感部分的影响;抑制高次模的微带圆盘腔带通滤波器。 相似文献
6.
7.
Siba Prasada Panigrahi Santanu Kumar Nayak Sasmita Kumari Padhy 《International Journal of Adaptive Control and Signal Processing》2008,22(7):705-716
This paper presents a neuro‐fuzzy network (NFN) where all its parameters can be tuned simultaneously using genetic algorithms (GAs). The approach combines the merits of fuzzy logic theory, neural networks and GAs. The proposed NFN does not require a priori knowledge about the system and eliminates the need for complicated design steps such as manual tuning of input–output membership functions, and selection of fuzzy rule base. Although, only conventional GAs have been used, convergence results are very encouraging. A well‐known numerical example derived from literature is used to evaluate and compare the performance of the network with other equalizing approaches. Simulation results show that the proposed neuro‐fuzzy controller, all parameters of which have been tuned simultaneously using GAs, offers advantages over existing equalizers and has improved performance. From the perspective of application and implementation, this paper is very interesting as it provides a new method for performing blind equalization. The main contribution of this paper is the use of learning algorithms to train a feed‐forward neural network for M‐ary QAM and PSK signals. This paper also provides a platform for researchers of the area for further development. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
8.
This paper presents an application of digital signal processing to data acquired by the radio imaging method (RIM) that was adopted to measure moisture distribution inside the human body. RIM was originally developed for the mining industry; we are applying the method to a biomedical measurement because of its simplicity, economy, and safety. When a two‐dimensional image was constructed from the measured data, the method provided insufficient resolution because the wavelength of the measurement medium, a weak electromagnetic wave in a VHF band, was longer than human tissues. We built and measured a phantom, a model simulating the human body, consisting of two water tanks representing large internal organs. A digital equalizer was applied to the measured values as a weight function, and images were reconstructed that corresponded to the original shape of the two water tanks. As a result, a two‐dimensional image containing two individual peaks corresponding to the original two small water tanks was constructed. The result suggests the method was applicable to biomedical measurement by the assistance of digital signal processing. This technique may be applicable to home‐based medical care and other situations in which safety, simplicity, and economy are important. 相似文献
9.
10.
本文给出了一种具有平行耦合线分裂环谐振器式L波段带通滤波器的近似设计方法及实验结果。这种滤波器结构简单,宜用于微波单片集成电路。 相似文献