全文获取类型
收费全文 | 13458篇 |
免费 | 374篇 |
国内免费 | 3篇 |
专业分类
化学 | 6950篇 |
晶体学 | 92篇 |
力学 | 302篇 |
数学 | 3036篇 |
物理学 | 3455篇 |
出版年
2021年 | 118篇 |
2020年 | 162篇 |
2019年 | 161篇 |
2018年 | 270篇 |
2017年 | 270篇 |
2016年 | 503篇 |
2015年 | 416篇 |
2014年 | 486篇 |
2013年 | 1003篇 |
2012年 | 647篇 |
2011年 | 854篇 |
2010年 | 490篇 |
2009年 | 422篇 |
2008年 | 584篇 |
2007年 | 563篇 |
2006年 | 476篇 |
2005年 | 302篇 |
2004年 | 317篇 |
2003年 | 257篇 |
2002年 | 261篇 |
2001年 | 194篇 |
2000年 | 198篇 |
1999年 | 161篇 |
1998年 | 151篇 |
1997年 | 138篇 |
1996年 | 130篇 |
1995年 | 119篇 |
1994年 | 107篇 |
1993年 | 115篇 |
1992年 | 130篇 |
1991年 | 109篇 |
1990年 | 126篇 |
1989年 | 110篇 |
1988年 | 112篇 |
1987年 | 107篇 |
1986年 | 103篇 |
1985年 | 151篇 |
1984年 | 164篇 |
1983年 | 128篇 |
1982年 | 139篇 |
1981年 | 133篇 |
1980年 | 131篇 |
1979年 | 140篇 |
1978年 | 152篇 |
1977年 | 115篇 |
1976年 | 143篇 |
1975年 | 129篇 |
1974年 | 133篇 |
1973年 | 105篇 |
1972年 | 90篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Thin films of polyelectrolyte/J aggregate dye bilayers with high absorption coefficient (6 nm thick with alpha approximately equal to 1.0 x 10(6) cm(-1)) inserted in an optical microcavity enable the cavity quantum electrodynamic strong coupling limit to be reached at room temperature with a coupling strength (Rabi splitting) of 265 +/- 15 meV. By embedding these films in a resonant cavity organic LED structure, we demonstrate the first emissive electrically pumped exciton-polariton device. 相似文献
992.
Alt C Anticic T Baatar B Barna D Bartke J Betev L Białkowska H Billmeier A Blume C Boimska B Botje M Bracinik J Bramm R Brun R Buncić P Cerny V Christakoglou P Chvala O Cramer JG Csató P Darmenov N Dimitrov A Dinkelaker P Eckardt V Farantatos G Flierl D Fodor Z Foka P Freund P Friese V Gál J Gaździcki M Georgopoulos G Gładysz E Grebieszkow K Hegyi S Höhne C Kadija K Karev A Kliemant M Kniege S Kolesnikov VI Kollegger T Kornas E Korus R Kowalski M Kraus I Kreps M van Leeuwen M Lévai P Litov L 《Physical review letters》2005,94(19):192301
Results are presented on Omega production in central Pb+Pb collisions at 40 and 158A GeV beam energy. For the first time in heavy ion reactions, rapidity distributions and total yields were measured for the sum Omega(-) + Omega(+) at 40A GeV and for Omega(-) and Omega(+) separately at 158A GeV. The yields are strongly underpredicted by the string-hadronic UrQMD model but agree better with predictions from hadron gas models. 相似文献
993.
We present a new analytical method that systematically improves the convergence of path integrals of a generic N-fold discretized theory. Using it we calculate the effective actions S(p) for p< or =9, which lead to the same continuum amplitudes as the starting action, but that converge to that continuum limit as 1/N(p). We checked this derived speedup in convergence by performing Monte Carlo simulations on several different models. 相似文献
994.
Aleksandar Ivić 《Central European Journal of Mathematics》2005,3(2):203-214
Let Δ(x) denote the error term in the Dirichlet divisor problem, and E(T) the error term in the asymptotic formula for the mean square of
. If E
*(t)=E(t)-2πΔ*(t/2π) with
, then we obtain
and
It is also shown how bounds for moments of | E
*(t)| lead to bounds for moments of
. 相似文献
995.
We propose an all-electrical nanostructure where pure spin current is induced in the transverse voltage probes attached to a quantum-coherent ballistic one-dimensional ring when unpolarized charge current is injected through its longitudinal leads. Tuning of the Rashba spin-orbit coupling in a semiconductor heterostructure hosting the ring generates quasiperiodic oscillations of the predicted spin-Hall current due to spin-sensitive quantum-interference effects caused by the difference in the Aharonov-Casher phase accumulated by opposite spin states. Its amplitude is comparable to that of the spin-Hall current predicted for finite-size (simply connected) two-dimensional electron gases, while it gets reduced gradually in wide two-dimensional rings or due to spin-independent disorder. 相似文献
996.
Exotic superconducting properties of have provided strong support for an unconventional pairing symmetry. However, the extensive efforts over the past decade have not yet unambiguously resolved the controversy about the pairing symmetry in this material. While recent phase-sensitive experiments using flux modulation in Josephson junctions consisting of and a conventional superconductor have been interpreted as conclusive evidence for a chiral spin-triplet pairing, we propose here an alternative interpretation. We show that an overlooked chiral spin-singlet pairing is also compatible with the observed phase shifts in Josephson junctions and propose further experiments which would distinguish it from its spin-triplet counterpart. 相似文献
997.
de Vaulx C Julien MH Berthier C Horvatić M Bordet P Simonet V Chen DP Lin CT 《Physical review letters》2005,95(18):186405
Crystallographic, magnetic, and NMR properties of a Na1CoO2 single crystal with x approximately = 1 are presented. We identify the stoichiometric Na1CoO2 phase, which is shown to be a nonmagnetic insulator, as expected for homogeneous planes of Co3+ ions with S = 0. In addition, we present evidence that, because of slight average Na deficiency, chemical and electronic phase separation leads to a segregation of Na vacancies into the well-defined, magnetic, Na0.8CoO2 phase. The importance of phase separation is discussed in the context of magnetic order for x approximately = 0.8 and the occurrence of a metal-insulator transition for x --> 1. 相似文献
998.
Tolić-Nørrelykke IM Munteanu EL Thon G Oddershede L Berg-Sørensen K 《Physical review letters》2004,93(7):078102
The viscoelastic properties of the cytoplasm of living yeast cells were investigated by studying the motion of lipid granules naturally occurring in the cytoplasm. A large frequency range of observation was obtained by a combination of video-based and laser-based tracking methods. At time scales from 10(-4) to 10(2) s, the granules typically perform subdiffusive motion with characteristics different from previous measurements in living cells. This subdiffusive behavior is thought to be due to the presence of polymer networks and membranous structures in the cytoplasm. Consistent with this hypothesis, we observe that the motion becomes less subdiffusive upon actin disruption. 相似文献
999.
Using a density functional approach, we study the structural and magnetic properties of the pyrox-ene compound NaTiSi2O6. While all previous workers are taking that NaTiSi2O6 is a quasi-one-dimensional S=1/2 system, our theoretical results indicate that this is a Haldane S=1 chain compound below the phase transition at 210 K. A good agreement is obtained between the calculated and the measured Ti-Ti distances in the dimerized low temperature phase. We present a simple explanation of the flow of the unusual phase transition which is taking place in this compound. 相似文献
1000.
Studies of low-frequency resistance noise show that the dramatic change in the dynamics of the two-dimensional electron system (2DES) in Si that occurs near the metal-insulator transition (MIT) persists in high parallel magnetic fields B such that the 2DES is fully spin polarized. This strongly suggests that charge, as opposed to spin, degrees of freedom are responsible for this effect. In the metallic phase, however, noise is suppressed by a parallel B, pointing to the role of spins. At low B, the temperature dependence of conductivity in the metallic phase provides evidence for a MIT. 相似文献