全文获取类型
收费全文 | 1015篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
化学 | 387篇 |
晶体学 | 1篇 |
力学 | 21篇 |
数学 | 84篇 |
物理学 | 526篇 |
出版年
2022年 | 12篇 |
2021年 | 16篇 |
2020年 | 16篇 |
2019年 | 12篇 |
2018年 | 19篇 |
2017年 | 20篇 |
2016年 | 28篇 |
2014年 | 22篇 |
2013年 | 35篇 |
2012年 | 37篇 |
2011年 | 41篇 |
2010年 | 27篇 |
2009年 | 40篇 |
2008年 | 30篇 |
2007年 | 36篇 |
2006年 | 30篇 |
2005年 | 26篇 |
2004年 | 36篇 |
2003年 | 32篇 |
2002年 | 26篇 |
2001年 | 39篇 |
2000年 | 29篇 |
1999年 | 27篇 |
1998年 | 21篇 |
1997年 | 21篇 |
1996年 | 13篇 |
1995年 | 10篇 |
1994年 | 14篇 |
1993年 | 11篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 14篇 |
1988年 | 10篇 |
1986年 | 10篇 |
1985年 | 12篇 |
1984年 | 10篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1978年 | 11篇 |
1977年 | 8篇 |
1976年 | 13篇 |
1975年 | 9篇 |
1974年 | 12篇 |
1973年 | 23篇 |
1972年 | 12篇 |
1971年 | 16篇 |
1970年 | 9篇 |
1969年 | 13篇 |
1967年 | 10篇 |
排序方式: 共有1019条查询结果,搜索用时 172 毫秒
61.
V. A. Gavrichkov S. G. Ovchinnikov 《Journal of Experimental and Theoretical Physics》2004,98(3):556-564
The spectral density, dispersion relations, and the position of the Fermi level for n-doped compositions based on NCO and LCO were calculated within the framework of the generalized tight binding method. As distinguished from LCO, the dielectric gap in NCO is nonlinear in character. We observe a virtual level both at the bottom of the conduction band and at the top of the valence band in both compounds. However, its position corresponds to the extreme bottom of the conduction band in LCO and is 0.1–0.2 eV above the bottom in NCO. This explains why we observe Fermi level pinning in n-LCO as the concentration of the doping component grows and reproduce its absence in NCCO at low doping values. We also found both compositions to be unstable in a narrow concentration range with respect to a nonuniform charge density distribution. The relation between the phase diagram for NCCO and the calculated electronic structure is discussed. 相似文献
62.
63.
Brown AM Ovchinnikov MV Stern CL Mirkin CA 《Journal of the American Chemical Society》2004,126(44):14316-14317
A novel reaction involving the halide-induced rearrangement of ligands within supramolecular Rh(I) complexes containing hemilabile ligands is presented. Three analogous bis- and trishemilabile ligands have been synthesized to construct bi- and trimetallic Rh(I) macrocyclic complexes. An intentionally added halide source results in the formal rotation of only one hemilabile ligand along the axis that is perpendicular to the plane defined by the aryl backbone of the hemilabile ligands. X-ray structures, as determined by X-ray crystallography, of key intermediates and products are presented. 相似文献
64.
The integral cross sections for elastic scattering and spin exchange for proton impact on atomic hydrogen show several oscillations in the energy range 0.01-1.0 eV that cannot be associated with resonances or the glory effect. A complex angular momentum analysis using computed Regge trajectories shows that each peak of the oscillatory structure is predominantly associated with at most three trajectories. In this way, the peaks are related to the L=0 bound states of H+ 2. The complex angular momentum theory for integral cross sections that we introduce shows that such oscillations are a general feature of potential scattering. 相似文献
65.
I. G. Bostrem A. S. Boyarchenkov A. A. Konovalov A. S. Ovchinnikov V. E. Sinitsyn 《Journal of Experimental and Theoretical Physics》2003,97(3):615-623
The possibility of realizing a quantum plateau of magnetization in [Mn(hfac)2BNOR] metal-organic compounds is investigated theoretically. A model of a one-dimensional ferrimagnetic chain (5/2, 1) is used for calculating the magnetization as a function of an external field by the method of discrete path integral representation (DPIR). Within this model, the coexistence of classical and quantum plateaus of magnetization is revealed. It is shown that the critical field Hc1 that destroys the classical plateau (ground-state magnetization) is determined by the optical gap in zero field, which is estimated by the matrix-product method and a numerical method of exact diagonalization (recursion method). 相似文献
66.
A. A. Borisov V. A. Gavrichkov S. G. Ovchinnikov 《Journal of Experimental and Theoretical Physics》2003,97(4):773-780
The electronic structure of p-type doped HTSC cuprates is calculated by explicitly taking into account strong electron correlations. The smooth evolution of the electronic structure from undoped antiferro-magnetic to optimally and heavily doped paramagnetic compositions is traced. For a low doping level, in-gap impurity-type states are obtained, at which the Fermi level is pinned in the low-doping region. These states are separated by a pseudogap from the valence band. The Fermi surfaces calculated for the paramagnetic phase for various concentrations of holes are in good agreement with the results of ARPES experiments and indicate a gradual change in the Fermi surface from the hole type to the electron type. 相似文献
67.
E. V. Kuz’min S. G. Ovchinnikov D. J. Singh 《Journal of Experimental and Theoretical Physics》2003,96(6):1124-1130
The spins of Ru5+ ions in Sr2YRuO6 form a face-centered cubic lattice with antiferromagnetic nearest neighbor interaction J≈25 meV. The antiferromagnetic structure of the first type experimentally observed below the Néel temperature T N =26 K corresponds to four frustrated spins of 12 nearest neighbors. In the Heisenberg model in the spin-wave approximation, the frustrations already cause instability of the antiferromagnetic state at T=0 K. This state is stabilized by weak anisotropy D or exchange interaction I with the next-nearest neighbors. Low D/J~I/J~10?3 values correspond to the experimental T N and sublattice magnetic moment values. 相似文献
68.
By on the analyzing the general structure of the Green function of a strongly correlated electron system, it is shown that, for the regime of strong correlations, Luttinger’s theorem should be generalized in the following way: the volume of the Fermi surface of the system of noninteracting particles is equal to that of the quasiparticles in the strongly correlated system with due regard for the spectral weight of the quasiparticles. An investigation of the t-J model and of the Hubbard model, as applied to the paramagnetic nonsuperconducting phase, shows that the generalized Luttinger theorem is valid for these models. 相似文献
69.
A new approach is developed to study the relaxation of concentrations to equilibrium in reversible bimolecular reactions. For A+B <==> C, a general analytic expression is derived for the amplitude of the power law (t(-d/2)) asymptotics for arbitrary diffusion coefficients and concentrations of the reactants. Our formalism is based on the analysis of the time correlation functions describing the equilibrium fluctuations of the concentrations. This powerful and simple procedure can be readily used to study other bimolecular reactions such as A+B <==> C+D. 相似文献
70.
A method for detecting ultraviolet photons from Xe 2 * deexitation with an efficiency of nearly 100% is proposed. This method allows a reliable discrimination between Xe (Ar) recoil nuclei and background electrons. As a result, the β and γ background is almost completely suppressed. The neutron background can be reduced by water shielding and by selection of events involving only one recoil nucleus. The developed grid screen will remove the photon feedback. The small prototype TPC with a preliminary multiplication of ionization electrons in a proportional gap and a subsequent detection of the multiplied charges in the induction gap is constructed. The shape of an electron component of the proportional signal is obtained in this chamber for Penning mixtures. A chamber 636 mm long is now being prepared for WIMP searches. A background of about 10?5 event/(keV kg d) can be obtained in this experiment. 相似文献