全文获取类型
收费全文 | 1740篇 |
免费 | 261篇 |
国内免费 | 176篇 |
专业分类
化学 | 1288篇 |
晶体学 | 20篇 |
力学 | 96篇 |
综合类 | 13篇 |
数学 | 184篇 |
物理学 | 576篇 |
出版年
2024年 | 1篇 |
2023年 | 41篇 |
2022年 | 54篇 |
2021年 | 63篇 |
2020年 | 87篇 |
2019年 | 74篇 |
2018年 | 56篇 |
2017年 | 59篇 |
2016年 | 82篇 |
2015年 | 89篇 |
2014年 | 103篇 |
2013年 | 121篇 |
2012年 | 170篇 |
2011年 | 190篇 |
2010年 | 112篇 |
2009年 | 99篇 |
2008年 | 107篇 |
2007年 | 104篇 |
2006年 | 93篇 |
2005年 | 72篇 |
2004年 | 69篇 |
2003年 | 34篇 |
2002年 | 35篇 |
2001年 | 15篇 |
2000年 | 27篇 |
1999年 | 38篇 |
1998年 | 37篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 15篇 |
1994年 | 16篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 15篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有2177条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
65.
Jian-Ming Zhang Shang-Ru Zhai Bin Zhai Qing-Da An Ge Tian 《Journal of Sol-Gel Science and Technology》2012,64(2):347-357
Multifunctional nanomaterials with task-specific physicochemical properties, especially core?Cshell nanostructures with Fe3O4 core and NH2-functional shells (Fe3O4@SiO2?CNH2), have been extensively investigated as high-performance adsorbents, catalysts and catalyst supports; and in most cases the controllable sol?Cgel technique is the choice for fabrication of this kind of widely applied materials. Herein, we demonstrated that mono-dispersed and spherical Fe3O4@SiO2?CNH2 nanomaterials with magnetic response core, NH2-functional shell structure can be facilely prepared by co-condensation of TEOS with APTMS using a versatile sol?Cgel process. It was shown that the proper usage of APTMS and appropriate pre-hydrolysis time of TEOS were crucial and key steps for formation of highly uniform and desirable amino loading Fe3O4@SiO2?CNH2 materials. The TEOS pre-hydrolysis and the critical time (around 90?min) before the addition of APTMS prove to be vital for uniform structure evolution, while the appropriate concentration of APTMS (~2.28?mmol?L?1 in our system) leads to well-dispersed materials with relatively high loading of amino functionality. The as-prepared Fe3O4@SiO2?CNH2 magnetic nanoparticles prepared under optimum conditions possessing superparamagnetic behavior, uniform core?Cshell structure (~200?nm in diameter), relatively large BET surface area (~138?m2/g) and high incorporation of amino-functionality (~2.90?wt?%). 相似文献
66.
67.
68.
69.
A 2-dimensional gradual period photonic heterostructure was made with holography by use of non-uniform swelling effect of dichromated gelatin during processing. In this structure, the symmetric point group of triangle lattice was debased to C2V from C6V. Theoretical analysis and experimental results show that omnidirectional band gap in visible range can be achieved with this kind of heterostructure made by low refractive index materials. 相似文献
70.