全文获取类型
收费全文 | 1755篇 |
免费 | 193篇 |
国内免费 | 328篇 |
专业分类
电工技术 | 85篇 |
综合类 | 179篇 |
化学工业 | 57篇 |
金属工艺 | 59篇 |
机械仪表 | 387篇 |
建筑科学 | 31篇 |
矿业工程 | 9篇 |
能源动力 | 35篇 |
轻工业 | 14篇 |
水利工程 | 7篇 |
石油天然气 | 16篇 |
武器工业 | 32篇 |
无线电 | 832篇 |
一般工业技术 | 240篇 |
冶金工业 | 48篇 |
原子能技术 | 52篇 |
自动化技术 | 193篇 |
出版年
2024年 | 10篇 |
2023年 | 17篇 |
2022年 | 32篇 |
2021年 | 36篇 |
2020年 | 57篇 |
2019年 | 31篇 |
2018年 | 34篇 |
2017年 | 61篇 |
2016年 | 80篇 |
2015年 | 102篇 |
2014年 | 123篇 |
2013年 | 109篇 |
2012年 | 127篇 |
2011年 | 153篇 |
2010年 | 117篇 |
2009年 | 124篇 |
2008年 | 142篇 |
2007年 | 157篇 |
2006年 | 133篇 |
2005年 | 125篇 |
2004年 | 78篇 |
2003年 | 59篇 |
2002年 | 51篇 |
2001年 | 44篇 |
2000年 | 46篇 |
1999年 | 41篇 |
1998年 | 33篇 |
1997年 | 26篇 |
1996年 | 31篇 |
1995年 | 20篇 |
1994年 | 17篇 |
1993年 | 16篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 6篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有2276条查询结果,搜索用时 15 毫秒
31.
32.
33.
讨论了利用法拉第镜补偿光在光纤中传输的偏振波动,介绍了量子密码术中基于法拉第镜的即插即用系统,并对即插即用系统进行简单相位编码分析。在系统中干涉脉冲遵循确切相同的路径,确保非常高的稳定性和自我补偿,使用法拉第镜自动补偿光纤中的任何双折射效应和偏振相关损耗。 相似文献
34.
Shiau-Shin Cheng Mohan Ramesh Guan-Yuan Chen Chun-Lin Fung Li-Ming Chen Meng-Chyi Wu Hong-Cheu Lin Chih-Wei Chu 《Organic Electronics》2013,14(9):2284-2289
Organic vertical-type triodes (OVTs) based on the cascade energy band structure as emitter layer are studied. The electric characteristics were dramatically enhanced while incorporating the cascade energy under current driving and voltage driving modes. The improvement is attributed to that injection carriers can obtain higher energy through a stepwise energy level. When the device has a layered structure of F16CuPC (10 nm)/PTCDI (10 nm)/pentacene (100 nm) in emitter, it exhibits a common-base transport factor of 0.99 and a common-emitter current gain of 225 under current driving mode and exhibits a high current modulation-exceeding ?520 μA for a low collector voltage of ?5 V and a base voltage of ?5 V and the current on/off ratio of 103 under voltage driving mode. Furthermore, we realized first organic current mirror that exhibited out/in current ratio of 0.75 and output resistance of 105 Ω by using the OVTs. 相似文献
35.
36.
Kwang Myung Jeon Su Yeon Park Chan Jun Chun Nam In Park Hong Kook Kim 《ETRI Journal》2017,39(3):398-405
In this paper, an artificial stereo extension method that creates stereophonic sound from a mono sound source is proposed. The proposed method first trains deep neural networks (DNNs) that model the nonlinear relationship between the dominant and residual signals of the stereo channel. In the training stage, the band‐wise log spectral magnitude and unwrapped phase of both the dominant and residual signals are utilized to model the nonlinearities of each sub‐band through deep architecture. From that point, stereo extension is conducted by estimating the residual signal that corresponds to the input mono channel signal with the trained DNN model in a sub‐band domain. The performance of the proposed method was evaluated using a log spectral distortion (LSD) measure and multiple stimuli with a hidden reference and anchor (MUSHRA) test. The results showed that the proposed method provided a lower LSD and higher MUSHRA score than conventional methods that use hidden Markov models and DNN with full‐band processing. 相似文献
37.
在对浅海近程噪声源定位研究时,针对多途环境和左右舷模糊问题,采用了组合阵与时反技术相结合的方法。利用矢量水听器的单边指向性去除虚假声源的干扰,并利用时间反转镜技术抑制多途效应的影响,从而实现了浅海近程声源定位。 相似文献
38.
39.
腔衰荡法四腔镜反射率及腔内吸收测量 总被引:1,自引:0,他引:1
利用腔衰荡四腔镜轮换的方法 ,在常态下测得了四腔镜的反射率 ,同时得到了腔内对测量光的吸收损耗 相似文献
40.
Fermin Esparza-Alfaro Antonio J. Lopez-Martin Ramon G. Carvajal Jaime Ramirez-Angulo 《Microelectronics Journal》2014
A design approach to achieve low-voltage micropower class AB CMOS cascode current mirrors is presented. Both class AB operation and dynamic cascode biasing are based on the use of Quasi-Floating Gate transistors. They allow high linearity for large signal currents and accurately set quiescent currents without requiring extra power consumption or supply voltage requirements. Measurement results show that dynamic cascode biasing allows a wider input range and a linearity improvement of more than 23 dB with respect to the use of conventional biasing. A THD value better than −35 dB is measured for input amplitudes up to 100 times the bias currents. Two class AB current mirror topologies are proposed, with slightly different ways to achieve class AB operation and dynamic biasing. The proposed current mirrors, fabricated in a 0.5 µm CMOS technology, are able to operate with a supply voltage of 1.2 V and a quiescent power consumption of only 36 µW, using a silicon area <0.025 mm2. 相似文献