全文获取类型
收费全文 | 6669篇 |
免费 | 216篇 |
国内免费 | 798篇 |
专业分类
电工技术 | 121篇 |
综合类 | 366篇 |
化学工业 | 986篇 |
金属工艺 | 513篇 |
机械仪表 | 338篇 |
建筑科学 | 277篇 |
矿业工程 | 46篇 |
能源动力 | 56篇 |
轻工业 | 557篇 |
水利工程 | 123篇 |
石油天然气 | 193篇 |
武器工业 | 4篇 |
无线电 | 646篇 |
一般工业技术 | 2760篇 |
冶金工业 | 158篇 |
原子能技术 | 108篇 |
自动化技术 | 431篇 |
出版年
2024年 | 118篇 |
2023年 | 405篇 |
2022年 | 490篇 |
2021年 | 480篇 |
2020年 | 163篇 |
2019年 | 114篇 |
2018年 | 92篇 |
2017年 | 93篇 |
2016年 | 94篇 |
2015年 | 161篇 |
2014年 | 133篇 |
2013年 | 154篇 |
2012年 | 745篇 |
2011年 | 992篇 |
2010年 | 208篇 |
2009年 | 124篇 |
2008年 | 546篇 |
2007年 | 421篇 |
2006年 | 428篇 |
2005年 | 337篇 |
2004年 | 217篇 |
2003年 | 135篇 |
2002年 | 131篇 |
2001年 | 130篇 |
2000年 | 87篇 |
1999年 | 113篇 |
1998年 | 112篇 |
1997年 | 94篇 |
1996年 | 66篇 |
1995年 | 82篇 |
1994年 | 41篇 |
1993年 | 23篇 |
1992年 | 31篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 19篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 13篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 20篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有7683条查询结果,搜索用时 15 毫秒
71.
Jiun-Haw Lee Xinyu Zhu Yi-Hsin Lin Wing Kit Choi Tien-Chun Lin Sheng-Chih Hsu Hoang-Yan Lin Shin-Tson Wu 公伟刚 朱正龙 周立 《现代显示》2006,(10):30-36
一种高环境对比度(A-CR)和大开口率的显示器已经从理论上证明,并通过把一个正常显黑反射型显示器(NB-RLCD)和一个有机电致发光器件(OLED)堆垛的实验加以证明。这种前后双置(以下称为tandem型)的器件组合可以分别在明亮或昏暗的环境下切换NB-RLCD模式或OLED模式。RLCD的正常显黑特性也可以提升OLED模式工作时的A-CR性能。为了在RLCD模式下获得更好的图像品质,一个复杂并且具有传输功能的结构被用于消除镜面反射和提高可视角至CR﹥2:1超过55°的锥面可视角度。另外,这样的结构也可以提高OLED49.4%的表面量子效率。在我们的实验里,忽略环境亮度因素并使A-CR保持在100:1以上。 相似文献
72.
73.
74.
在便携电子产品市场,无线网络的出现让人们能够随时随地进行高效的无线通信,而这正是设计便携式电子产品时的首要考虑因素之一。无线调制解调器是一种与无线网络而非电话系统连接的调制解调器。当用户连接无线调制解调器时,实际上就直接连接了无线互联网服务提供商。全球移动通信系统(GlobalSystemforMobile,GSM)和通用分包无线服务(GeneralPacketRadioService,GPRS)无线调制解调器均由uSB的VBUS线供电,提供了一种实现通用式便携设备环境的好方法。不过,这种调制解调器设计也带来了功率管理问题,因为GSM和GPRS发送器需要高达2A的峰值电流,而这却超过了USB电源的最大电流容量。 相似文献
75.
With the recent increase in routing App usage, it is urgent to analyze the impact of inevitable information delay in routing Apps on traffic. To analyze the negative impact of such delayed routing Apps on traffic, this paper investigates the impact of ideal and delayed routing Apps on traffic. Firstly, the effect of ideal routing Apps has been explored with theoretical analysis and derivation based on a macroscopic network model. Then, an extended network model is built to characterize the delayed routing. The impact of such delayed routing Apps is investigated by simulation experiments while considering routing usage proportion and amount of delay. The results demonstrate that ideal navigation does improve traffic efficiency, but in some cases, delayed navigation is even worse than no navigation. 相似文献
76.
New energy power generation equipment has the characteristics of diurnal, perturbative, seasonal, and periodic power generation, which makes new power optical communication network(POCN) more dynamic and changeable. This is directly reflected in the dynamics of the link risk and service importance of the POCN. In this paper, aiming at the problem of the dynamic importance of service in POCN, and the resulting power optical communication network reliability decline problem, a new energy POCN dyna... 相似文献
77.
1 Introduction High power laser diode arrays (LDA) have many advan- tages such as small volume, long working life, high slope efficiency and high optical density, so they have many applications in medical treatment, material pro- cessing, and for the pumping source of solid laser and etc. But unfortunately, the LDA can not be easy to use directly in these fields because of their poor beam quality and extremely asymmetric divergent beams (!x≈ 5°~10°and !y≈20°~35°, for example), so it … 相似文献
78.
1 Introduction Fiber lasers have been developed for more than forty years since Snitzer!s proposal and the demonstration of Nd- doped fiber in 1961 [1]. But fiber lasers have not been attracted considerable attention until the develop- ment of the low- loss fiber fabrication technology and the high power semiconductor laser technology recently. Actually,it is the application and development of fiber communication technology that has promoted the rapid development of fiber laser. Fiber laser, … 相似文献
79.
Yu Jiang Chou Chun Tung Yang Zhongkai Du Xu Wang Tai 《电子科学学刊(英文版)》2006,23(5):798-800
I. Introduction Streaming media has been widely used over the Internet in recent years. However, the growing use in streaming media, which generally has large size, can have a significant impact on the user perceived latency and network congestion. A popular approach to reduce the response time and backbone bandwidth consumption is to deploy proxy caches at the edge of the Internet. Due to the large size and different popularity for different part of the streaming video, it is not practical … 相似文献
80.
LIU Yang WANG Xiao-bing SUN Bin CHENG Yong WANG Li-jun 《半导体光子学与技术》2006,12(4):242-244
An all-fiber based Er^3+ :Yb^3+ co-doped double clad fiber laser operating at 1 550 nm is demonstrated. By using 9 m long Er^3+ : Yb^3+ co-doped fiber(EYDF) as the gain medium, and using a pair of fiber Bragg gratings as wavelength filters, the line-width of the output laser is as narrow as 0.2 nm and the output power is more than 6 mW. The fluorescent effect of the laser before its emission is also studied. And it is found that the Er^3+ : Yb^3+ co-doped double-clad fiber laser also exhibits a high gain for Yb^3+ transition near 1 080 nm. 相似文献