全文获取类型
收费全文 | 658篇 |
免费 | 14篇 |
国内免费 | 10篇 |
专业分类
化学 | 416篇 |
晶体学 | 11篇 |
力学 | 11篇 |
数学 | 48篇 |
物理学 | 196篇 |
出版年
2020年 | 5篇 |
2019年 | 3篇 |
2017年 | 9篇 |
2016年 | 9篇 |
2015年 | 11篇 |
2014年 | 2篇 |
2013年 | 23篇 |
2012年 | 40篇 |
2011年 | 44篇 |
2010年 | 21篇 |
2009年 | 13篇 |
2008年 | 54篇 |
2007年 | 37篇 |
2006年 | 54篇 |
2005年 | 38篇 |
2004年 | 36篇 |
2003年 | 33篇 |
2002年 | 28篇 |
2001年 | 11篇 |
2000年 | 19篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 6篇 |
1993年 | 20篇 |
1992年 | 16篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 5篇 |
1972年 | 3篇 |
1968年 | 8篇 |
1966年 | 2篇 |
排序方式: 共有682条查询结果,搜索用时 31 毫秒
51.
52.
Haverkort MW Hu Z Tanaka A Ghiringhelli G Roth H Cwik M Lorenz T Schüssler-Langeheine C Streltsov SV Mylnikova AS Anisimov VI de Nadai C Brookes NB Hsieh HH Lin HJ Chen CT Mizokawa T Taguchi Y Tokura Y Khomskii DI Tjeng LH 《Physical review letters》2005,94(5):056401
Utilizing a sum rule in a spin-resolved photoelectron spectroscopic experiment with circularly polarized light, we show that the orbital moment in LaTiO3 is strongly reduced from its ionic value, both below and above the Ne el temperature. Using Ti L2,3 x-ray absorption spectroscopy as a local probe, we found that the crystal-field splitting in the t2g subshell is about 0.12-0.30 eV. This large splitting does not facilitate the formation of an orbital liquid. 相似文献
53.
Grenier S Hill JP Kiryukhin V Ku W Kim YJ Thomas KJ Cheong SW Tokura Y Tomioka Y Casa D Gog T 《Physical review letters》2005,94(4):047203
We report a study of electronic excitations in manganites exhibiting a range of ground states, using resonant inelastic x-ray scattering (RIXS) at the Mn K edge. Excitations with temperature dependent changes correlated with the magnetism were observed as high as 10 eV. By calculating Wannier functions, and finite-q response functions, we associate this dependence with intersite d-d excitations. The calculated dynamical structure factor is found to be similar to the RIXS spectra. 相似文献
54.
Magnon excitation in a ferromagnetic state of Sm(0.55)Sr(0.45)MnO(3) located on the verge of the metal-insulator transition has been studied in terms of the neutron scattering experiment. The anomalous magnon dispersion with the zone-boundary softening is well described by the Heisenberg model with extended exchange coupling constants J(s). In particular the fourth neighbor coupling J(4) is as large as 0.6 times the nearest neighbor one J(1). Theoretical analysis based on the local density approximation + Hubbard U band calculation reveals that this one-dimensional exchange path is due to the (3z(2)-r(2))-type orbital correlation, in sharp contrast to previous proposals. 相似文献
55.
Deisenhofer J Braak D Krug von Nidda HA Hemberger J Eremina RM Ivanshin VA Balbashov AM Jug G Loidl A Kimura T Tokura Y 《Physical review letters》2005,95(25):257202
We report on the discovery of a novel triangular phase regime in the system La1-xSrxMnO3 by means of electron spin resonance and magnetic susceptibility measurements. This phase is characterized by the coexistence of ferromagnetic entities within the globally paramagnetic phase far above the magnetic ordering temperature. The nature of this phase can be understood in terms of Griffiths singularities arising due to the presence of correlated quenched disorder in the orthorhombic phase. 相似文献
56.
Thomas KJ Hill JP Grenier S Kim YJ Abbamonte P Venema L Rusydi A Tomioka Y Tokura Y McMorrow DF Sawatzky G van Veenendaal M 《Physical review letters》2004,92(23):237204
We have utilized resonant x-ray diffraction at the Mn L(II,III) edges in order to directly compare magnetic and orbital correlations in Pr0.6Ca0.4MnO3. Comparing the widths of the magnetic and orbital diffraction peaks, we find that the magnetic correlation length exceeds that of the orbital order by nearly a factor of 2. Furthermore, we observe a large (approximately 3 eV) spectral weight shift between the magnetic and orbital resonant line shapes, which cannot be explained within the classic Goodenough picture of a charge-ordered ground state. To explain the shift, we calculate the orbital and magnetic resonant diffraction line shapes based on a relaxed charge-ordered model. 相似文献
57.
In a polar ferrimagnet GaFeO3, we have found a novel magneto-optical effect, termed x-ray nonreciprocal directional dichroism (XNDD), that the x-ray absorption at around the K edge of an Fe ion depends on whether the x-ray propagation vector is parallel or antiparallel to the outer product of the magnetization and electric-polarization vectors. The XNDD spectroscopy as demonstrated here can be a useful tool to probe the local magnetism in noncentrosymmetric systems such as magnetic interfaces and nanostructures. 相似文献
58.
The magnetic and electrical properties of high-quality single crystals of A-site disordered (solid solution) Ln0.5Ba0.5MnO3 are investigated near the phase boundary between the spin-glass insulator and colossal-magnetoresistive ferromagnetic metal, locating near Ln=Sm. The temperature dependence of the ac susceptibility and the x-ray diffuse scattering of Eu0.5Ba0.5MnO3 are analyzed in detail. The uniformity of the random potential perturbation in Ln0.5Ba0.5MnO3 crystals with a small bandwidth yields, rather than the phase separation, an homogeneous short ranged charge or orbital order which gives rise to a nearly atomic spin-glass state. Remarkably, this microscopically disordered "charge-exchange-glass" state alone is able to bring forth the colossal magnetoresistance. 相似文献
59.
Second harmonic generation (SHG) induced by spontaneous magnetization has been investigated for a polar ferromagnetic crystal of GaFeO3. The Kerr rotation of the second harmonic light becomes gigantic with decreasing temperature below the magnetic transition temperature (approximately =205 K), e.g., as large as 73 degrees at 100 K. The magnetic domains can be visualized by using that large nonlinear Kerr rotation. The spectrum of the magnetization-induced SHG as measured indicates the two-photon resonant electronic process on a Fe3+ ion in the crystal. 相似文献
60.
Optical conductivity spectra sigma(omega) were used to investigate the effect of orbital ordering on the electronic structure of Ca2RuO4. Our LDA+U calculation predicts Ru 4d(xy) ferro-orbital ordering at the ground state, and well explains the present sigma(omega) as well as the reported O 1s x-ray absorption spectra. Variation of temperature (T) causes a large change of spectral weight over several eV as well as collapse of a charge gap accompanied by elongation of the c-axis Ru-O bond length. These results clearly indicate that the d(xy) orbital ordering plays a crucial role in the metal-insulator transition and the T-dependent electronic structure on a large energy scale. 相似文献