全文获取类型
收费全文 | 1733篇 |
免费 | 41篇 |
国内免费 | 4篇 |
专业分类
化学 | 918篇 |
晶体学 | 9篇 |
力学 | 45篇 |
数学 | 198篇 |
物理学 | 608篇 |
出版年
2021年 | 13篇 |
2020年 | 12篇 |
2019年 | 17篇 |
2017年 | 13篇 |
2016年 | 27篇 |
2015年 | 15篇 |
2014年 | 27篇 |
2013年 | 87篇 |
2012年 | 57篇 |
2011年 | 82篇 |
2010年 | 58篇 |
2009年 | 29篇 |
2008年 | 78篇 |
2007年 | 98篇 |
2006年 | 68篇 |
2005年 | 58篇 |
2004年 | 60篇 |
2003年 | 29篇 |
2002年 | 57篇 |
2001年 | 45篇 |
2000年 | 38篇 |
1999年 | 17篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 18篇 |
1995年 | 30篇 |
1994年 | 36篇 |
1993年 | 39篇 |
1992年 | 32篇 |
1991年 | 26篇 |
1990年 | 21篇 |
1989年 | 16篇 |
1988年 | 28篇 |
1987年 | 14篇 |
1986年 | 19篇 |
1985年 | 32篇 |
1984年 | 17篇 |
1983年 | 17篇 |
1982年 | 24篇 |
1981年 | 20篇 |
1980年 | 27篇 |
1979年 | 24篇 |
1978年 | 31篇 |
1977年 | 21篇 |
1976年 | 32篇 |
1975年 | 34篇 |
1974年 | 20篇 |
1973年 | 33篇 |
1972年 | 15篇 |
1971年 | 15篇 |
排序方式: 共有1778条查询结果,搜索用时 31 毫秒
121.
122.
J.C. Hart R.D. Baker K.W. Bell J.A. Blissett I.J. Bloodworth T.A. Broome A.L. Lintern V.K. Magon R. Maybury A.G. Parham B.T. Payne D.H. Saxon T.G. Walker H.M. Watson M. Gay 《Nuclear Physics B》1980,166(1):73-83
Differential cross-section and polarization measurements for the reaction π?p → K0Σ0 are presented from 1395 to 2375 MeV/c incident beam momentum. The polarization data from an earlier experiment, from thershold to 1334 MeV/c, have been re-analysed by an improved method leading to a substantial reduction in the errors. 相似文献
123.
124.
125.
Techniques,computations, and conjectures for semi-topological <Emphasis Type="Italic">K</Emphasis>-theory 总被引:1,自引:0,他引:1
Eric M.?Friedlander Christian?HaesemeyerEmail author Mark E.?Walker 《Mathematische Annalen》2004,330(4):759-807
We establish the existence of an Atiyah-Hirzebruch-like spectral sequence relating the morphic cohomology groups of a smooth, quasi-projective complex variety to its semi-topological K-groups. This spectral sequence is compatible with (and, indeed, is built from) the motivic spectral sequence that relates the motivic cohomology and algebraic K-theory of varieties, and it is also compatible with the classical Atiyah-Hirzebruch spectral sequence in algebraic topology. In the second part of this paper, we use this spectral sequence in conjunction with another computational tool that we introduce — namely, a variation on the integral weight filtration of the Borel-Moore (singular) homology of complex varieties introduced by H. Gillet and C. Soulé – to compute the semi-topological K-theory of a large class of varieties. In particular, we prove that for curves, surfaces, toric varieties, projective rational three-folds, and related varieties, the semi-topological K-groups and topological K-groups are isomorphic in all degrees permitted by cohomological considerations. We also formulate integral conjectures relating semi-topological K-theory to topological K-theory analogous to more familiar conjectures (namely, the Quillen-Lichtenbaum and Beilinson-Lichtenbaum Conjectures) concerning mod-n algebraic K-theory and motivic cohomology. In particular, we prove a local vanishing result for morphic cohomology which enables us to formulate precisely a conjectural identification of morphic cohomology by A. Suslin. Our computations verify that these conjectures hold for the list of varieties above.Mathematics Subject Classification (2000): 19E20, 19E15, 14F43The first author was partially supported by the NSF and the NSAThe second author was supported by the Helen M. Galvin Fellowship of Northwestern UniversityThe third author was partially supported by the NSF and the NSA 相似文献
126.
127.
128.
Bifunctional, conjugated oligomers for orthogonal self-assembly: selectivity varies from planar substrates to nanoparticles 总被引:1,自引:0,他引:1
Walker BR Wassel RA Stefanescu DM Gorman CB 《Journal of the American Chemical Society》2004,126(50):16330-16331
A diphenylacetylene containing two different end groups (isonitrile and thioacetate) was synthesized, showing that the chemistry used to install each end group is compatible with that of the others. The isonitrile group binds preferentially to platinum, and the thiol group binds preferentially to gold. However, the selectivity was different when nanoparticles were compared to planar substrates. 相似文献
129.
Gerber MJ Kline SR Walker LM 《Langmuir : the ACS journal of surfaces and colloids》2004,20(20):8510-8516
The polymerization of elongated micellar structures offers a novel approach to the production of high-aspect-ratio, water-soluble amphiphilic nanorods. A cationic surfactant with a vinyl-containing counterion, cetyltrimethylammonium 4-vinylbenzoate, has been synthesized and polymerized to produce high-aspect-ratio nanoparticles which are insensitive to changes in solution conditions. Aggregates are polymerized over a range of initiator concentrations allowing for control of the product length. Small-angle neutron scattering and light scattering are used to characterize the dimensions of the polymerized aggregates, showing them to have a fixed radius of 2 nm and contour lengths varying from 96 to 340 nm. Proton NMR verifies the chemical structure and provides insight into the mobility of the aggregate components. Finally, gel permeation chromatography of the polymer extracted from the aggregates indicates that the polymerization reaction controls the aggregate dimensions. 相似文献
130.
Mihailov SJ Smelser CW Lu P Walker RB Grobnic D Ding H Henderson G Unruh J 《Optics letters》2003,28(12):995-997
High-quality retroreflecting fiber Bragg gratings were written in standard Ge-doped telecom fiber (Corning SMF-28) after a few minutes exposure with pulsed 800-nm, 120-fs laser radiation by use of a deep-etch silica zero-order nulled phase mask optimized for 800 nm. Induced index modulations of 1.9 x 10(-3) were achieved with peak power intensities of 1.2 x 10(13) W/cm2 without any fiber sensitization. The fiber gratings are stable and did not erase after 2 weeks at 300 degrees C. The primary mechanism of induced index change results from a structural modification to the fiber core. 相似文献