全文获取类型
收费全文 | 26166篇 |
免费 | 2624篇 |
国内免费 | 1283篇 |
专业分类
电工技术 | 1521篇 |
技术理论 | 5篇 |
综合类 | 1906篇 |
化学工业 | 4501篇 |
金属工艺 | 1502篇 |
机械仪表 | 1534篇 |
建筑科学 | 2069篇 |
矿业工程 | 767篇 |
能源动力 | 650篇 |
轻工业 | 2837篇 |
水利工程 | 437篇 |
石油天然气 | 1378篇 |
武器工业 | 177篇 |
无线电 | 3127篇 |
一般工业技术 | 2963篇 |
冶金工业 | 1139篇 |
原子能技术 | 233篇 |
自动化技术 | 3327篇 |
出版年
2024年 | 181篇 |
2023年 | 552篇 |
2022年 | 983篇 |
2021年 | 1306篇 |
2020年 | 962篇 |
2019年 | 863篇 |
2018年 | 923篇 |
2017年 | 960篇 |
2016年 | 856篇 |
2015年 | 1137篇 |
2014年 | 1418篇 |
2013年 | 1596篇 |
2012年 | 1763篇 |
2011年 | 1675篇 |
2010年 | 1519篇 |
2009年 | 1451篇 |
2008年 | 1383篇 |
2007年 | 1274篇 |
2006年 | 1243篇 |
2005年 | 988篇 |
2004年 | 751篇 |
2003年 | 949篇 |
2002年 | 1182篇 |
2001年 | 966篇 |
2000年 | 670篇 |
1999年 | 601篇 |
1998年 | 350篇 |
1997年 | 311篇 |
1996年 | 290篇 |
1995年 | 231篇 |
1994年 | 182篇 |
1993年 | 141篇 |
1992年 | 100篇 |
1991年 | 80篇 |
1990年 | 73篇 |
1989年 | 44篇 |
1988年 | 35篇 |
1987年 | 16篇 |
1986年 | 20篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 11篇 |
1959年 | 2篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
Lei He Yan Xuan Feng Zhang Xue Wang Huaqing Pan Junfeng Ren Meina Chen 《International Journal of Hydrogen Energy》2021,46(1):1096-1105
Bulk and surface properties of proton stability and transportation in Y and Nd co-doped BaCeO3 (BCYN), especially the effect of Nd segregation, were investigated by first-principles calculations. Since the structure of doped BaCeO3 at the operating temperature of proton-conducting has been unclear for a long time, we have summarized the latest experimental results and calculated the structure of the asymmetric BCYN for the first time. The results show that compared with Y, Nd doping promotes oxygen vacancy formation, however reduces proton stability. Our calculation can also provide a possible explanation for the formation of space charge layer at the grain boundary of doped BaCeO3 in experiment. Unlike the stable Y in BCYN, Nd is calculated to be easily segregated, which can facilitate both proton hydration and proton transportation near the surface. Moreover, Nd segregation at the grain boundary is predicted to be beneficial for proton transportation between grains. 相似文献
16.
17.
18.
Multimedia Tools and Applications - Understanding human emotions through facial expressions is key enabling technology for interactive robots. Most approaches of facial expression recognition are... 相似文献
19.
Qiang Wang Lei Shen Tong Xue Gao Cheng Cheng Zhi Huang Hong Jin Fan Yuan Ping Feng 《Advanced functional materials》2021,31(2):2002187
The {100} facet of single-crystalline TiO2(B) is an ideal platform for inserting Li ions, but it is hard to be obtained due to its high surface energy. Here, the single-crystalline TiO2(B) nanobelts from H2Ti3O7 with nearly 70% {100} facets exposed are synthesized, which significantly enhances Li-storage capacity. The first-principle calculations demonstrate an ab in-plane 2D diffusion through the exposed {100} facets. As a consequence, the nanobelts can significantly accommodate Li ions in LiTiO2 formula with specific capacity up to 335 mAh g−1, which is in good agreement with the electrochemical characterizations. Coating with conductive and protective poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), the cut-off discharge voltage is as low as 0.5 V, leading to a capacity of 160.7 mAh g−1 after 1500 cycles with a retention rate of 66% at 1C. This work provides a practical strategy to increase the Li-ion capacity and cycle stability by tailoring the crystal orientation and nanostructures. 相似文献
20.