全文获取类型
收费全文 | 39535篇 |
免费 | 3943篇 |
国内免费 | 1862篇 |
学科分类
工业技术 | 45340篇 |
出版年
2024年 | 94篇 |
2023年 | 799篇 |
2022年 | 1322篇 |
2021年 | 1996篇 |
2020年 | 1499篇 |
2019年 | 1133篇 |
2018年 | 1343篇 |
2017年 | 1409篇 |
2016年 | 1164篇 |
2015年 | 1679篇 |
2014年 | 2151篇 |
2013年 | 2414篇 |
2012年 | 2753篇 |
2011年 | 2961篇 |
2010年 | 2625篇 |
2009年 | 2199篇 |
2008年 | 2328篇 |
2007年 | 2081篇 |
2006年 | 2015篇 |
2005年 | 1746篇 |
2004年 | 1136篇 |
2003年 | 965篇 |
2002年 | 930篇 |
2001年 | 798篇 |
2000年 | 795篇 |
1999年 | 951篇 |
1998年 | 746篇 |
1997年 | 587篇 |
1996年 | 552篇 |
1995年 | 465篇 |
1994年 | 388篇 |
1993年 | 258篇 |
1992年 | 235篇 |
1991年 | 171篇 |
1990年 | 127篇 |
1989年 | 98篇 |
1988年 | 82篇 |
1987年 | 49篇 |
1986年 | 44篇 |
1985年 | 36篇 |
1984年 | 29篇 |
1983年 | 28篇 |
1982年 | 23篇 |
1981年 | 21篇 |
1980年 | 22篇 |
1979年 | 12篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1976年 | 8篇 |
1973年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
Zhang Junbao Huang Haojun Yang Changlin Liu Jizhao Fan Yinting Yang Guan 《Wireless Networks》2022,28(3):1301-1312
Wireless Networks - Although centrality is widely used to differentiate the importance of nodes for social-aware routing in mobile opportunistic networks (MONs), it is destination-agnostic since... 相似文献
2.
3.
4.
5.
6.
7.
8.
Qing Li Jun Wang Jie Ma Meng Ni Fan Yang Peng Liu Kuo Yang Lee Hsing-I Hsiang Deyuan Shen Dingyuan Tang 《Journal of the American Ceramic Society》2022,105(5):3375-3381
High-efficiency Yb:Y2O3 laser ceramics were fabricated using the vacuum-sintering plus hot isostatic pressing (HIP) without sintering additives. High-purity well-dispersed nanocrystalline Yb:Y2O3 powder was synthesized using a modified co-precipitation method in-house. The green bodies were first vacuum sintered at a temperature as low as 1430°C and then HIPed at 1450°C. Finally, the samples were air annealed at 800°C for 10 h. Although no sintering aids were used, full density of the samples with excellent optical homogeneity and an inline transmission of 80% at 400 nm could be obtained. Moreover, photodarkening phenomenon was not detected in the ceramics. Preliminary laser experiment with the fabricated ceramics in a two-mirror cavity has demonstrated 32 W continuous-wave (CW) output at ∼1077 nm with an optical-to-optical conversion efficiency of 58.2%. To the best of our knowledge, this is so far the highest CW output power and optical-to-optical conversion efficiency achieved with the Yb3+-doped sesquioxide ceramics in a simple two-mirror cavity. 相似文献
9.
10.
Fenqi Du Dongmei Yang Yue Sun Yang Jiao Feng Teng Haibo Fan 《Ceramics International》2021,47(4):4963-4971
Ultrawide band gap semiconductor materials have attracted considerable attention in recent years owing to their great potential in the photocatalytic field. In this study, Zn-doped Ga2O3 nanofibers with various concentrations were synthesized via electrospinning; they exhibited a superior photocatalytic degradation performance of rhodamine B dye compared to that of undoped Ga2O3 nanofibers. The Zn dopant replaced Ga sites via replacement doping, which could increase the concentration of oxygen vacancies and lead to enhanced photocatalytic properties. When the Zn concentration increased, a Ga2O3/ZnGa2O4 hybrid structure formed, which could further enhance the photocatalytic performance. The separation of photogenerated carriers due to Zn doping and heterojunctions were the primary causes of the enhanced photocatalytic performance. This study provides experimental data for the fabrication of high-performance photocatalysts based on Ga2O3 nanomaterials. 相似文献