全文获取类型
收费全文 | 13945篇 |
免费 | 987篇 |
国内免费 | 647篇 |
专业分类
电工技术 | 356篇 |
综合类 | 760篇 |
化学工业 | 1290篇 |
金属工艺 | 3527篇 |
机械仪表 | 609篇 |
建筑科学 | 1005篇 |
矿业工程 | 240篇 |
能源动力 | 496篇 |
轻工业 | 778篇 |
水利工程 | 50篇 |
石油天然气 | 286篇 |
武器工业 | 64篇 |
无线电 | 445篇 |
一般工业技术 | 1286篇 |
冶金工业 | 3872篇 |
原子能技术 | 112篇 |
自动化技术 | 403篇 |
出版年
2024年 | 57篇 |
2023年 | 188篇 |
2022年 | 333篇 |
2021年 | 421篇 |
2020年 | 411篇 |
2019年 | 299篇 |
2018年 | 276篇 |
2017年 | 451篇 |
2016年 | 476篇 |
2015年 | 414篇 |
2014年 | 841篇 |
2013年 | 814篇 |
2012年 | 961篇 |
2011年 | 1066篇 |
2010年 | 762篇 |
2009年 | 840篇 |
2008年 | 588篇 |
2007年 | 866篇 |
2006年 | 866篇 |
2005年 | 711篇 |
2004年 | 612篇 |
2003年 | 499篇 |
2002年 | 532篇 |
2001年 | 449篇 |
2000年 | 358篇 |
1999年 | 294篇 |
1998年 | 220篇 |
1997年 | 216篇 |
1996年 | 175篇 |
1995年 | 127篇 |
1994年 | 87篇 |
1993年 | 96篇 |
1992年 | 65篇 |
1991年 | 37篇 |
1990年 | 29篇 |
1989年 | 56篇 |
1988年 | 25篇 |
1987年 | 12篇 |
1986年 | 11篇 |
1985年 | 4篇 |
1984年 | 11篇 |
1982年 | 5篇 |
1980年 | 4篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
概述单板接长工艺研究进程,着重介绍国内外单板接长机组发展概况、技术性能比较,特点。还对单板接长机组在我国推广应用前景进行了评述。 相似文献
72.
Chunya Du Hui Liu Zhuang Cheng Shaoqin Zhang Zexing Qu Dezhi Yang Xianfeng Qiao Zujin Zhao Ping Lu 《Advanced functional materials》2023,33(45):2304854
The pursuit for efficient deep blue material is an ever-increasing issue in organic optoelectronics field. It is a long-standing challenge to achieve high external quantum efficiency (EQE) exceed 10% at brightness of 1000 cd m−2 with a Commission International de L'Eclairage (CIEy) <0.08 in non-doped organic light-emitting diodes (OLEDs). Herein, this study reports a deep blue luminogen, PPITPh, by bonding phenanthro[9,10-d]imidazole moiety with m-terphenyl group via benzene bridge. The non-doped OLED based on PPITPh exhibits an exceptionally high EQE of 11.83% with a CIE coordinate of (0.15, 0.07). The EQE still maintains 10.17% at the brightness of 1000 cd m−2, and even at a brightness as high as 10000 cd m−2, an EQE of 7.5% is still remained, representing the record-high result among non-doped deep-blue OLEDs at 1000 cd m−2. The unprecedented device performance is attributed to the reversed intersystem crossing process through hot exciton mechanism. Besides, the maximum EQE of orange phosphorescent OLED with PPITPh as host is 32.02%, and remains 31.17% at the brightness of 1000 cd m−2. Such minimal efficiency roll-off demonstrates that PPITPh is also an excellent phosphorescent host material. The result offers a new design strategy for the enrichment of high-efficiency deep blue luminogen. 相似文献
73.
74.
We offer an interdisciplinary study of computer science and social science, analyzing behavior surrounding three types of online events: political events, social events, and non-public events. Based on the intrinsic characteristics of the three event types, this paper creates an effective method to predict such events. We continuously followed and recorded data every 10 min for 10 months from September 14, 2012 to July 11, 2013, and collected over 14 million “hot” posts from Sina Weibo, the largest microblogging provider in China. After removing spammers and noises, we developed a database of 4180 hot online events and 7,761,395 threads. We found that people’s online behavior regarding event types varies in terms of follow-up statistics and the predictability of events. The Chinese are, typically, quite concerned with social affairs that relate most closely to their personal interests and preferences. People tend to cluster around political events more often than social events and non-public events. This is demonstrated by an algorithm embedded with a clustering growth pattern of events, which predicts the popularity of online political events above others. The statistical findings are justified by Habermas’ public sphere theory and the theory of vertical/horizontal collectivism/individualism. This research provides an interesting piece of computational social science work to assist in the analysis of incentives concerning China’s collective events. 相似文献
75.
阐述线路板的绿色表面涂覆的化学镀锡工艺的有关理论和技术,化学镀锡应用是实现取代热风整平表面涂覆绿色化的最重要的手段之一。我司第三代化学镀锡应用是突破目前化学沉锡的供应商共拥硫脲作为电位改变剂配方此环节,是一种新型独特的科技。 相似文献
76.
基于热备份的主备倒换在高端路由器中的应用 总被引:3,自引:0,他引:3
从高端路由器的可靠性出发,提出提高可靠性、减少故障持续时间的关键在于减少路由器主备倒换时间。文中通过对传统的主备倒换与热备份下的主备倒换进行比较,分析了热备份下的主备倒换在节省业务板和路由板的重启时间、业务板恢复配置时间、路由板路由学习聚合时间等方面的优势。同时详细介绍了基于热备份的主备倒换在高端路由器中的主要实现步骤,并对其技术特点和给用户提供的解决方案进行了阐述。 相似文献
77.
78.
79.
For the first time, a simple and accurate two-dimensional analytical model for the surface potential variation along the channel in fully depleted dual-material gate strained-Si-on-insulator (DMG SSOI) MOSFETs is developed. We investigate the improved short channel effect (SCE), hot carrier effect (HCE), drain-induced barrier-lowering (DIBL) and carrier transport efficiency for the novel structure MOSFET. The analytical model takes into account the effects of different metal gate lengths, work functions, the drain bias and Ge mole fraction in the relaxed SiGe buffer. The surface potential in the channel region exhibits a step potential, which can suppress SCE, HCE and DIBL. Also, strained-Si and SOI structure can improve the carrier transport efficiency, with strained-Si being particularly effective. Further,the threshold voltage model correctly predicts a "rollup" in threshold voltage with decreasing channel length ratios or Ge mole fraction in the relaxed SiGe buffer. The validity of the two-dimensional analytical model is verified using numerical simulations. 相似文献
80.
介绍了圆片级可靠性技术产生的背景,对其特点和作用作了详细的论述。测试内容上着重介绍了金属化完整性测试、氧化层完整性测试、连接完整性测试和热载流子注入测试,根据测试数据,对1.0μm工艺线单一失效机理的可靠性进行了评价,对不同测试结构的作用进行了说明。 相似文献