全文获取类型
收费全文 | 1817篇 |
免费 | 45篇 |
国内免费 | 11篇 |
专业分类
化学 | 1197篇 |
晶体学 | 6篇 |
力学 | 83篇 |
数学 | 325篇 |
物理学 | 262篇 |
出版年
2022年 | 16篇 |
2021年 | 28篇 |
2020年 | 23篇 |
2019年 | 37篇 |
2018年 | 29篇 |
2017年 | 15篇 |
2016年 | 54篇 |
2015年 | 27篇 |
2014年 | 36篇 |
2013年 | 74篇 |
2012年 | 80篇 |
2011年 | 97篇 |
2010年 | 55篇 |
2009年 | 65篇 |
2008年 | 87篇 |
2007年 | 97篇 |
2006年 | 89篇 |
2005年 | 100篇 |
2004年 | 81篇 |
2003年 | 71篇 |
2002年 | 47篇 |
2001年 | 25篇 |
2000年 | 31篇 |
1999年 | 34篇 |
1998年 | 21篇 |
1997年 | 27篇 |
1996年 | 23篇 |
1995年 | 22篇 |
1994年 | 21篇 |
1993年 | 13篇 |
1992年 | 23篇 |
1991年 | 11篇 |
1990年 | 17篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 15篇 |
1985年 | 25篇 |
1984年 | 22篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1974年 | 9篇 |
1969年 | 7篇 |
1888年 | 8篇 |
排序方式: 共有1873条查询结果,搜索用时 10 毫秒
91.
92.
Rosarina Carpignano Piero Savarino Ermanno Barni Guido Viscardi 《Journal of heterocyclic chemistry》1984,21(2):561-568
The shielding parameters of benz-X-azolyl substituents in various positions of the pyridine nucleus were determined by means of a regression analysis procedure. Analogously the shielding contributions of pyridyl substituents on homocyclic protons of benz-X-azoles were derived. The results evidence some interactions between the two heterocyclic systems when the benz-X-azolyl substituents are linked at the pyridine α-position. 相似文献
93.
94.
95.
96.
Guido Corbò 《Physics letters. [Part B]》1982,116(4):298-300
We present some results from the computation of the charged lepton energy distribution in the decay b → c + ? + taking into account first order QCD corrections. 相似文献
97.
We study the nature of the ground state of the two-dimensional extended boson Hubbard model on a square lattice by quantum Monte Carlo methods. We demonstrate that strong but finite on-site interaction U along with a comparable nearest-neighbor repulsion V result in a thermodynamically stable supersolid ground state for densities larger than 1/2, in contrast to fillings less than 1/2 or for very large U, where the checkerboard supersolid is unstable towards phase separation. We discuss the relevance of our results to realizations of supersolids using cold bosonic atoms in optical lattices. 相似文献
98.
Liebschner A Hanke W Miersch L Dehnhardt G Sauerland M 《The Journal of the Acoustical Society of America》2005,117(1):436-441
Auditory systems of cetaceans are considered highly specialized for underwater sound processing, whereas the extent of their hearing capacity in air is still a point of issue. In this study, the sensitivity to airborne sound in a male tucuxi (Sotalia fluviatilis guianensis) was tested by means of a go/no go response paradigm. Auditory thresholds were obtained from 2 to 31.5 kHz. Compared to the hearing thresholds of other dolphins as well as of amphibian mammals, the sensitivity to airborne sound of the test subject is low from 2 to 8 kHz, with the highest threshold at 4 kHz. Thresholds at 16 and 31.5 kHz reveal a sharp increase in hearing sensitivity. Thus, although not obtained in this study, the upper aerial hearing limit is in the ultrasonic range. A comparison of the present data with the underwater audiogram of the same test subject referred to sound intensity indicates that the sensitivity of Sotalia to underwater sound is generally better than to airborne sound. 相似文献
99.
Guido Gentile Vieri Mastropietro Michela Procesi 《Communications in Mathematical Physics》2005,256(2):437-490
We consider the nonlinear string equation with Dirichlet boundary conditions utt–uxx=(u), with (u)=u3+O(u5) odd and analytic, 0, and we construct small amplitude periodic solutions with frequency for a large Lebesgue measure set of close to 1. This extends previous results where only a zero-measure set of frequencies could be treated (the ones for which no small divisors appear). The proof is based on combining the Lyapunov-Schmidt decomposition, which leads to two separate sets of equations dealing with the resonant and non-resonant Fourier components, respectively the Q and the P equations, with resummation techniques of divergent powers series, allowing us to control the small divisors problem. The main difficulty with respect to the nonlinear wave equations utt–uxx+Mu=(u), M0, is that not only the P equation but also the Q equation is infinite-dimensional. 相似文献
100.
We use quantum Monte Carlo simulations to determine the finite temperature phase diagram and to investigate the thermal and quantum melting of stripe phases in a two-dimensional hard-core boson model. At half filling and low temperatures the stripes melt at a first order transition. In the doped system, the melting transitions of the smectic phase at high temperatures and the superfluid smectic (supersolid) phase at low temperatures are either very weakly first order, or of second order with no clear indications for an intermediate nematic phase. 相似文献