全文获取类型
收费全文 | 5760篇 |
免费 | 124篇 |
国内免费 | 24篇 |
专业分类
化学 | 3292篇 |
晶体学 | 27篇 |
力学 | 136篇 |
数学 | 707篇 |
物理学 | 1746篇 |
出版年
2021年 | 40篇 |
2020年 | 65篇 |
2019年 | 56篇 |
2016年 | 97篇 |
2015年 | 84篇 |
2014年 | 90篇 |
2013年 | 245篇 |
2012年 | 220篇 |
2011年 | 279篇 |
2010年 | 144篇 |
2009年 | 137篇 |
2008年 | 249篇 |
2007年 | 307篇 |
2006年 | 254篇 |
2005年 | 263篇 |
2004年 | 276篇 |
2003年 | 199篇 |
2002年 | 171篇 |
2001年 | 118篇 |
2000年 | 122篇 |
1999年 | 71篇 |
1998年 | 49篇 |
1997年 | 70篇 |
1996年 | 82篇 |
1995年 | 68篇 |
1994年 | 90篇 |
1993年 | 91篇 |
1992年 | 114篇 |
1991年 | 76篇 |
1990年 | 84篇 |
1989年 | 67篇 |
1988年 | 52篇 |
1987年 | 64篇 |
1986年 | 68篇 |
1985年 | 108篇 |
1984年 | 99篇 |
1983年 | 76篇 |
1982年 | 72篇 |
1981年 | 86篇 |
1980年 | 62篇 |
1979年 | 70篇 |
1978年 | 72篇 |
1977年 | 61篇 |
1976年 | 57篇 |
1975年 | 67篇 |
1974年 | 72篇 |
1973年 | 81篇 |
1972年 | 58篇 |
1971年 | 42篇 |
1970年 | 41篇 |
排序方式: 共有5908条查询结果,搜索用时 140 毫秒
41.
Giovanni Bruno Maria M. Giangregorio April S. Brown Soojeong Choi 《Applied Surface Science》2006,253(1):219-223
GaN is grown on Si-face 4H-SiC(0 0 0 1) substrates using remote plasma-assisted methods including metalorganic chemical vapour deposition (RP-MOCVD) and molecular beam epitaxy (MBE). Real time spectroscopic ellipsometry is used for monitoring all the steps of substrate pre-treatments and the heteroepitaxial growth of GaN on SiC. Our characterization emphasis is on understanding the nucleation mechanism and the GaN growth mode, which depend on the SiC surface preparation. 相似文献
42.
There are over 100 accreting neutron stars in our galaxy, in which matter (typically H/He) is tidally transferred from a secondary companion to the neutron star. Accretion of this matter perturbs the thermal structure of the interior away from that of an isolated cooling neutron star. In this paper. we review how this accretion induces reactions in the crust of the neutron star that keep the interior hot. If the accretion is intermittent, then the heated surface layers are directly observable when accretion stops. This heating also affects the unstable ignition of light elements in the neutron star envelope. Observations of the neutron star cooling following an accretion outburst can in principle constrain the thermal properties of the crust and core. 相似文献
43.
The resistance to slow crack growth (SCG) was measured in binary blends of high density polyethylene (HDPE) and 5–10% concentrations of model ethylene-butene random copolymers by measuring the time to failure (tf) under a constant stress intensity. An increase of tf with the addition of the copolymer if the copolymer could crystallize and the increase was greater the higher branch density. The copolymer with 117 branches/1000C could not crystallize and therefore its blend had a tf that was less than that of the HDPE. The fracture energies of the blends as determined by their resistance to SCG were compared with the energy by rapid fracture, Jc, as previously measured by Rhee and Crist. It is concluded that SCG is more sensitive to variations in the microstructure than is rapid fracture and that the differences in SCG behavior can be qualitatively explained in terms of the differences in microstructure of the blends. ©1995 John Wiley & Sons, Inc. 相似文献
44.
J. S. Bell's classic 1966 review paper on the foundations of quantum mechanics led directly to the Bell nonlocality theorem. It is not widely appreciated that the review paper contained the basic ingredients needed for a nonlocality result which holds in certain situations where the Bell inequality is not violated. We present in this paper a systematic formulation and evaluation of an argument due to Stairs in 1983, which establishes a nonlocality result based on the Bell-Kochen-Specker paradox in quantum mechanics. 相似文献
45.
46.
Abe F Amidei D Apollinari G Atac M Auchincloss P Baden AR Bamberger A Barbaro-Galtieri A Barnes VE Bedeschi F Behrends S Belforte S Bellettini G Bellinger J Bensinger J Beretvas A Berge JP Bertolucci S Bhadra S Binkley M Blair R Blocker C Booth AW Brandenburg G Brown D Buckley E Byon A Byrum KL Campagnari C Campbell M Carey R Carithers W Carlsmith D Carroll JT Cashmore R Cervelli F Chadwick K Chiarelli G Chinowsky W Cihangir S Clark AG Connor D Contreras M Cooper J Cordelli M Crane D Curatolo M 《Physical review letters》1990,65(18):2243-2246
47.
We use the topological tool of Nielsen fixed-point theory to study the controllability of perturbed linear control processes whose control space can be reduced to a finite-dimensional one. These methods produce a lower bound on the number of controls that achieve a given target. We concentrate particularly on the case where the perturbation has sublinear growth, and we exhibit examples of multiple controls of various types that are detected by the Nielsen theory method.This research was partly supported by the Research Grant Teoria del Controllo dei Sistemi Dinamici, Ministero della Pubblica Istruzione, Roma, Italy. 相似文献
48.
49.
Abe F Amidei D Apollinari G Ascoli G Atac M Auchincloss P Baden AR Barbaro-Galtieri A Barnes VE Bedeschi F Behrends S Belforte S Bellettini G Bellinger J Bensinger J Beretvas A Berge P Bertolucci S Bhadra S Binkley M Blair R Blocker C Bofill J Booth AW Brandenburg G Brown D Byon A Byrum KL Campbell M Carey R Carithers W Carlsmith D Carroll JT Cashmore R Cervelli F Chadwick K Chapin T Chiarelli G Chinowsky W Cihangir S Cline D Connor D Contreras M Cooper J Cordelli M Curatolo M Day C DelFabbro R 《Physical review D: Particles and fields》1990,41(5):1722-1725
50.