全文获取类型
收费全文 | 2807篇 |
免费 | 274篇 |
国内免费 | 279篇 |
专业分类
化学 | 520篇 |
晶体学 | 27篇 |
力学 | 736篇 |
综合类 | 46篇 |
数学 | 808篇 |
物理学 | 1223篇 |
出版年
2024年 | 3篇 |
2023年 | 23篇 |
2022年 | 39篇 |
2021年 | 40篇 |
2020年 | 63篇 |
2019年 | 69篇 |
2018年 | 66篇 |
2017年 | 72篇 |
2016年 | 92篇 |
2015年 | 69篇 |
2014年 | 114篇 |
2013年 | 221篇 |
2012年 | 130篇 |
2011年 | 176篇 |
2010年 | 154篇 |
2009年 | 144篇 |
2008年 | 151篇 |
2007年 | 168篇 |
2006年 | 182篇 |
2005年 | 179篇 |
2004年 | 155篇 |
2003年 | 125篇 |
2002年 | 122篇 |
2001年 | 99篇 |
2000年 | 98篇 |
1999年 | 98篇 |
1998年 | 76篇 |
1997年 | 47篇 |
1996年 | 54篇 |
1995年 | 58篇 |
1994年 | 40篇 |
1993年 | 28篇 |
1992年 | 25篇 |
1991年 | 33篇 |
1990年 | 29篇 |
1989年 | 21篇 |
1988年 | 11篇 |
1987年 | 17篇 |
1986年 | 8篇 |
1985年 | 13篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1974年 | 3篇 |
1973年 | 6篇 |
排序方式: 共有3360条查询结果,搜索用时 31 毫秒
101.
Multireference calculations on low-lying states and the X~3 Π_u -~3 Π_g absorption spectra of indium dimers 下载免费PDF全文
Multireference configuration interaction calculations are carried out on 11 Λ-S low-lying electronic states of indium dimers. The states are investigated with spin-orbit pseudopotentials via the state-interacting method, and characterized by fitted spectroscopic constants based on computed potential energy curves. The vibrational structures of the double-potential well 0+g (I) ( 3 Σ g ) state are also analyzed. The experimentally observed absorption spectrum centred at ~ 13000cm-1 is simulated and assigned to X 3 Πu (v=0)-3Πg transition according to the present ab initio calculations on transition energies and dipole moment functions. 相似文献
102.
Based on the Dirac equation describing an electron moving in a uniform and cylindrically symmetric magnetic field which may be the result of the self-consistent mean field of the electrons themselves in a neutron star, we have obtained the eigen solutions and the orbital magnetic moments of electrons in which each eigen orbital can be calculated. From the eigen energy spectrum we find that the lowest energy level is the highly degenerate orbitals with the quantum numbers pZ=0, n=0, and m≥0. At the ground state, the electrons fill the lowest eigen states to form many Landau magnetic cells and each cell is a circular disk with the radius λfree and the thickness λe, where λfree is the electron mean free path determined by Coulomb cross section and electron density and λe is the electron Compton wavelength. The magnetic moment of each cell and the number of cells in the neutron star are calculated, from which the total magnetic moment and magnetic field of the neutron star can be calculated. The results are compared with the observational data and the agreement is reasonable. 相似文献
103.
Electronic structure properties including bond lengths, bond angles, dipole moments (μ), energies, band gaps, NMR parameters of the isotropic and anisotropic chemical shielding parameters for the sites of various atoms were calculated using the density functional theory for Si, Ge, Sn, Pb doped (6,3) Chiral single-walled carbon nanotubes (SWCNTs). The calculations indicated that average bond lengths were as: Pb3C>Sn3C>Ge3C>Si3C>C3C. The dipole moments for Si, Ge, Sn, Pb doped (6,3) Chiral single-walled carbon nanotubes structures show fairly large changes with respect to the pristine model. 相似文献
104.
In this study, the effect of ultraviolet treatment on the band bending at the poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate)/indium tin oxide (PEDOT:PSS/ITO) interfaces were researched. The authors suggested that ultraviolet treatment could lead to a reduction in the band bending at the PEDOT:PSS/ITO interface, owing to the removal of carbon contamination at the ITO surfaces and a decrease in the number of the trap-states at the PEDOT:PSS/ITO interface. 相似文献
105.
We consider trapezoidal load-time pulses with linearly increasing and affinely decreasing durations equal to integer multiples of the time period of the first bending mode of vibration of a linearly elastic structure. For arbitrary spatial distributions of loads applied to monolithic and laminated orthotropic plates, it is shown through numerical solutions that plates’ vibrations become miniscule after the load is removed. This phenomenon is independent of the dwell time (i.e., the time duration between the rising and the falling portions) during which the load is kept constant. The primary reason for this response is that for such time-dependent loads, nearly all of plate’s strain energy is concentrated in deformations corresponding to the fundamental bending mode of vibration. Thus plate’s deformations can be studied by taking the mode shape of the 1st bending mode as the basis function and reducing the problem to that of solving a single second-order ordinary differential equation. We have verified this postulate by comparing strain energies computed from the 3-dimensional deformations of different plate geometries and boundary conditions with those determined by using the single degree of freedom (DoF) model. Thus for trapezoidal time-dependent loads applied on plates, the 1 DoF model provides reasonably accurate results and saves considerable computational effort. 相似文献
106.
Effects of deposition layer position film are systematically investigated. Because the and number/density on local bending of a thin deposition layer interacts with the thin film at the interface and there is an offset between the thin film neutral surface and the interface, the deposition layer generates not only axial stress but also bending moment. The bending moment induces an instant out-of-plane deflection of the thin film, which may or may not cause the socalled local bending. The deposition layer is modeled as a local stressor, whose location and density are demonstrated to be vital to the occurrence of local bending. The thin film rests on a viscous layer, which is governed by the Navier-Stokes equation and behaves like an elastic foundation to exert transverse forces on the thin film. The unknown feature of the axial constraint force makes the governing equation highly nonlinear even for the small deflection chse. The constraint force and film transverse deflection are solved iteratively through the governing equation and the displacement constraint equation of immovable edges. This research shows that in some special cases, the deposition density increase does not necessarily reduce the local bending. By comparing the thin film deflections of different deposition numbers and positions, we also present the guideline of strengthening or suppressing the local bending. 相似文献
107.
The experimental one-, three-, and five-quasiparticle bands in ~(177)Lu are analyzed by the particle-number conserving (PNC) method for treating the cranked shell model with pairing interaction, in which the blocking effects are taken into account exactly. The experimental moments of inertia are reproduced very well by PNC calculations with us free parameter. 相似文献
108.
109.
Using Breit-Wigner resonance relation,bounds on the magnetic moment of the tau-neutrino are calculated through the reaction e+e-→v(v)γ at the neutral boson pole in the framework of a superstringinspired E6 model which has one extra low-energy neutral gauge boson and a LRSM. 相似文献
110.