全文获取类型
收费全文 | 3835篇 |
免费 | 284篇 |
国内免费 | 203篇 |
专业分类
电工技术 | 159篇 |
技术理论 | 1篇 |
综合类 | 176篇 |
化学工业 | 696篇 |
金属工艺 | 178篇 |
机械仪表 | 203篇 |
建筑科学 | 314篇 |
矿业工程 | 108篇 |
能源动力 | 115篇 |
轻工业 | 219篇 |
水利工程 | 58篇 |
石油天然气 | 217篇 |
武器工业 | 17篇 |
无线电 | 471篇 |
一般工业技术 | 458篇 |
冶金工业 | 240篇 |
原子能技术 | 51篇 |
自动化技术 | 641篇 |
出版年
2024年 | 22篇 |
2023年 | 56篇 |
2022年 | 126篇 |
2021年 | 142篇 |
2020年 | 104篇 |
2019年 | 96篇 |
2018年 | 117篇 |
2017年 | 128篇 |
2016年 | 98篇 |
2015年 | 140篇 |
2014年 | 163篇 |
2013年 | 228篇 |
2012年 | 218篇 |
2011年 | 253篇 |
2010年 | 206篇 |
2009年 | 217篇 |
2008年 | 192篇 |
2007年 | 200篇 |
2006年 | 172篇 |
2005年 | 182篇 |
2004年 | 115篇 |
2003年 | 93篇 |
2002年 | 96篇 |
2001年 | 88篇 |
2000年 | 127篇 |
1999年 | 144篇 |
1998年 | 116篇 |
1997年 | 90篇 |
1996年 | 91篇 |
1995年 | 66篇 |
1994年 | 42篇 |
1993年 | 42篇 |
1992年 | 27篇 |
1991年 | 21篇 |
1990年 | 23篇 |
1989年 | 12篇 |
1988年 | 18篇 |
1987年 | 4篇 |
1986年 | 10篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 2篇 |
1977年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有4322条查询结果,搜索用时 15 毫秒
81.
Sang Gi Kim Hoon Soo Park Kyoung Il Na Seong Wook Yoo Jongil Won Jin Gun Koo Sang Hoon Chai Hyung‐Moo Park Yil Suk Yang Jin Ho Lee 《ETRI Journal》2013,35(4):632-637
In this paper, we propose a superjunction trench gate MOSFET (SJ TGMOSFET) fabricated through a simple p pillar forming process using deep trench and boron silicate glass doping process technology to reduce the process complexity. Throughout the various boron doping experiments, as well as the process simulations, we optimize the process conditions related with the p pillar depth, lateral boron doping concentration, and diffusion temperature. Compared with a conventional TGMOSFET, the potential of the SJ TGMOSFET is more uniformly distributed and widely spread in the bulk region of the n drift layer due to the trenched p‐pillar. The measured breakdown voltage of the SJ TGMOSFET is at least 28% more than that of a conventional device. 相似文献
82.
83.
Zhengguo Li Kun Li Changyun Wen Yeng Chai Soh 《Communications, IEEE Transactions on》2003,51(8):1306-1312
The paper proposes a digital chaotic secure communication by introducing a magnifying glass concept, which is used to enlarge and observe minor parameter mismatch so as to increase the sensitivity of the system. The encryption method is based on a one-time pad encryption scheme, where the random key sequence is replaced by a chaotic sequence generated via a Chua's circuit. We make use of an impulsive control strategy to synchronize two identical chaotic systems embedded in the encryptor and the decryptor, respectively. The lengths of impulsive intervals are piecewise constant and, as a result, the security of the system is further improved. Moreover, with the given parameters of the chaotic system and the impulsive control law, an estimate of the synchronization time is derived. The proposed cryptosystem is shown to be very sensitive to parameter mismatch and hence the security of the chaotic secure communication system is greatly enhanced. 相似文献
84.
Seung-Ho Shin Kyu-Ho Park Young-Joon Chai Tae-Yong Kim 《Signal Processing: Image Communication》2010,25(4):255-267
H.264/AVC supports variable block motion compensation, multiple reference frames, 1/4-pixel motion vector accuracy, and in-loop deblocking filter, compared with previous video coding standards. While these coding techniques are major functions for video compression improvement, they lead to high computational complexity at the same time. For the H.264 video coding techniques to be actually applied on low-end/low-bit rates terminals more extensively, it is essential to improve the coding efficiency. Currently the H.264 deblocking filter, which can improve the subjective quality of video, is hardly used on low-end terminals due to computational complexity.In this paper, we propose an enhanced method of deblocking filter that efficiently reduces the blocking artifacts occurring during the low-bit rates video coding. In the ‘variable block-based deblocking filter (VBDF)’ proposed in this paper, the temporal and spatial characteristics of moving pictures are extracted using the variable block-size information of motion compensation, the filter mode is classified into four different modes according to the moving-picture characteristics, and the adaptive filtering is executed in the separate modes. The proposed VBDF can reduce the blocking artifacts, prevent excessive blurring effects, and achieve about 30–40% computational speedup at about the same PSNR compared with the existing methods. 相似文献
85.
86.
介绍了在立式巷道支架试验台上,对不同结构形式平顶形柱腿可缩金属支架的试验结果。分析了支架的力学特征和影响柱腿可缩性的因素。 相似文献
87.
88.
Lin Zhang Xinyu Wang Meixiu Sun Ying Chai Zhaofeng Hao 《Journal of Modern Optics》2013,60(10):1395-1405
The direction cosine for expressing photon propagation in tubular tissue is given. The condition for the dispersed photons' reflection and refraction on the interface is analysed. A Monte Carlo simulation model for simulating light propagation in a two-layered cylindrical biological tissue is constructed. Using this model, we studied the absorbed photon distribution with different tissue parameters in the case of a circular flat beam injecting the tissue. Finally, the photon distribution in a two-layered blood vessel is given by a model constructed according to the reported tissue parameters of the human body. 相似文献
89.
90.
助剂在羊毛低温染色中的应用 总被引:4,自引:0,他引:4
综述了羊毛低温染色助剂的种类、染色机理及其研究现状,主要介绍了羊毛低温促染剂WLD、SLD、CMR以及纳米型促染荆、二乙胺预处理对羊毛染色性能的影响。论述了酶对羊毛低温染色性能的影响,包括蛋白酶HAP、Ncwol Lan L处理,氧化剂和蛋白酶联合处理,蛋白酶与壳聚糖预处理工艺的影响。指出低温助剂和酶处理在羊毛低温染色工艺中应用效果良好,具有推广前景。 相似文献