全文获取类型
收费全文 | 6073篇 |
免费 | 260篇 |
国内免费 | 54篇 |
专业分类
化学 | 4528篇 |
晶体学 | 43篇 |
力学 | 225篇 |
综合类 | 2篇 |
数学 | 853篇 |
物理学 | 736篇 |
出版年
2024年 | 11篇 |
2023年 | 63篇 |
2022年 | 312篇 |
2021年 | 313篇 |
2020年 | 218篇 |
2019年 | 238篇 |
2018年 | 228篇 |
2017年 | 185篇 |
2016年 | 319篇 |
2015年 | 212篇 |
2014年 | 235篇 |
2013年 | 566篇 |
2012年 | 380篇 |
2011年 | 399篇 |
2010年 | 253篇 |
2009年 | 222篇 |
2008年 | 263篇 |
2007年 | 267篇 |
2006年 | 214篇 |
2005年 | 190篇 |
2004年 | 173篇 |
2003年 | 146篇 |
2002年 | 156篇 |
2001年 | 56篇 |
2000年 | 66篇 |
1999年 | 46篇 |
1998年 | 31篇 |
1997年 | 47篇 |
1996年 | 42篇 |
1995年 | 33篇 |
1994年 | 42篇 |
1993年 | 32篇 |
1992年 | 33篇 |
1991年 | 30篇 |
1990年 | 45篇 |
1989年 | 27篇 |
1988年 | 24篇 |
1987年 | 27篇 |
1986年 | 29篇 |
1985年 | 32篇 |
1984年 | 20篇 |
1983年 | 19篇 |
1982年 | 26篇 |
1981年 | 20篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1978年 | 12篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1975年 | 6篇 |
排序方式: 共有6387条查询结果,搜索用时 15 毫秒
1.
Manjumol K. A. Jayasankar M. Vidya K. Mohamed A. Peer Nair Balagopal N. Warrier K. G. K. 《Journal of Sol-Gel Science and Technology》2015,74(1):161-167
Journal of Sol-Gel Science and Technology - High temperature stable brookite rich titanium dioxide of average crystallite size 20&;nbsp;nm has been prepared by a novel aqueous sol–gel... 相似文献
2.
In this paper, the deformation of the Heisenberg algebra, consistent with both the generalized uncertainty principle and doubly special relativity, has been analyzed. It has been observed that, though this algebra can give rise to fractional derivative terms in the corresponding quantum mechanical Hamiltonian, a formal meaning can be given to them by using the theory of harmonic extensions of function. Depending on this argument, the expression of the propagator of the path integral corresponding to the deformed Heisenberg algebra, has been obtained. In particular, the consistent expression of the one dimensional free particle propagator has been evaluated explicitly. With this propagator in hand, it has been shown that, even in free particle case, normal generalized uncertainty principle and doubly special relativity show very much different result. 相似文献
3.
4.
5.
Inner derivations and norm equality 总被引:3,自引:0,他引:3
Mohamed Barraa Mohamed Boumazgour 《Proceedings of the American Mathematical Society》2002,130(2):471-476
We characterize when the norm of the sum of two bounded operators on a Hilbert space is equal to the sum of their norms.
6.
The Aza-Diels-Alder reaction of aldimines with isoeugenol is described. New 1,2,3,4-tetrahydroquinoline and quinoline structures are reported. The stereo- and regioselectivities of the [4+2] cycloaddition are discussed. 相似文献
7.
Using a double Suzuki cross-coupling reaction ortho- or para-bromobenzyl bromides are easily transformed into unsymmetrical diaryl (or heteroaryl) methanes 相似文献
8.
Mohamed Hilmy Elnagdi Ramadan Maawad Abdel-Motaleb Mona Mustafa Mohamed Foad Zayed Eman Moustafa Kamel 《Journal of heterocyclic chemistry》1987,24(6):1677-1681
The behaviour of several 2-amino-3-cyano-4H-pyran derivatives toward a variety of nucleophilic reagents is reported. 相似文献
9.
10.
Ultraviolet and blue-green photoluminescence (PL) was investigated on multicrystalline silicon (mc-Si) samples chemically etched by Secco and Yang solutions. The samples were characterized by dislocation density (105-106 cm−2). The form of etched pits is triangular with Yang etch and like a honeycomb with Secco etch as observed with a scanning electron microscope (SEM). These textures of mc-Si wafers give a PL activity similar to that obtained with nanostructures of porous silicon (PS) as reported in the literature. The ultraviolet PL spectra observed with Yang etch shift to the blue-green spectrum range when applying Secco etch. In our experiments we have observed 3-5 μm diameter macro pores separated by a high density of nanowalls. These observations suggest that the origin of the PL activity are quantum dots resulting from the silicon nanocrystallites obtained after few minutes of chemical etching. 相似文献