全文获取类型
收费全文 | 1664篇 |
免费 | 109篇 |
国内免费 | 107篇 |
专业分类
化学 | 556篇 |
晶体学 | 3篇 |
力学 | 125篇 |
综合类 | 3篇 |
数学 | 519篇 |
物理学 | 674篇 |
出版年
2024年 | 2篇 |
2023年 | 24篇 |
2022年 | 24篇 |
2021年 | 35篇 |
2020年 | 38篇 |
2019年 | 40篇 |
2018年 | 42篇 |
2017年 | 34篇 |
2016年 | 32篇 |
2015年 | 47篇 |
2014年 | 76篇 |
2013年 | 121篇 |
2012年 | 65篇 |
2011年 | 81篇 |
2010年 | 76篇 |
2009年 | 111篇 |
2008年 | 134篇 |
2007年 | 128篇 |
2006年 | 97篇 |
2005年 | 65篇 |
2004年 | 67篇 |
2003年 | 76篇 |
2002年 | 60篇 |
2001年 | 48篇 |
2000年 | 45篇 |
1999年 | 43篇 |
1998年 | 34篇 |
1997年 | 34篇 |
1996年 | 20篇 |
1995年 | 16篇 |
1994年 | 18篇 |
1993年 | 10篇 |
1992年 | 22篇 |
1991年 | 9篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有1880条查询结果,搜索用时 15 毫秒
111.
In this paper, we propose a high order Fourier spectral-discontinuous Galerkin method for time-dependent Schrödinger–Poisson equations in 3-D spaces. The Fourier spectral Galerkin method is used for the two periodic transverse directions and a high order discontinuous Galerkin method for the longitudinal propagation direction. Such a combination results in a diagonal form for the differential operators along the transverse directions and a flexible method to handle the discontinuous potentials present in quantum heterojunction and supperlattice structures. As the derivative matrices are required for various time integration schemes such as the exponential time differencing and Crank Nicholson methods, explicit derivative matrices of the discontinuous Galerkin method of various orders are derived. Numerical results, using the proposed method with various time integration schemes, are provided to validate the method. 相似文献
112.
Feng Dai 《Constructive Approximation》2005,22(3):417-436
Let $\sigma_k^\delta$ denote the Cesaro means of order $\delta > -1$ of the spherical harmonic expansions on the unit sphere $S^{d-1}$, and let $E_j(f, H^1)$ denote the best approximation of $f$ in the Hardy space $H^1(S^{d-1})$ by spherical polynomials of degree at most $j$. It is known that $\lambda:= (d-2)/2$ is the critical index for the summability of the Cesaro means on $H^1(S^{d-1})$. The main result of this paper states that, for $ f\in H^1(S^{d-1})$, $$\sum_{j=0}^N \f 1{j+1} \|\sigma_j^\lambda (f) -f\|_{H^1}\approx \sum_{j=0}^N \f 1{j+1} E_j(f, H^1),$$ where “$\approx$” means that the ratio of both sides lies between two positive constants independent of $f$ and $N$. 相似文献
113.
Alexandre Almeida Humberto Rafeiro 《Journal of Mathematical Analysis and Applications》2008,340(2):1336-1346
We study the inversion problem of the Bessel potential operator within the frameworks of the weighted Lebesgue spaces with variable exponent. The inverse operator is constructed by using approximative inverse operators. This generalizes some classical results to the variable exponent setting. 相似文献
114.
I. Chudinovich 《Journal of Mathematical Analysis and Applications》2008,339(2):1024-1043
The initial-boundary value problems with the Dirichlet and Neumann boundary conditions arising in the theory of bending of thermoelastic plates with transverse shear deformation are reduced to time-dependent boundary integral equations by means of layer potentials. The solvability of these equations is then investigated in Sobolev-type spaces. 相似文献
115.
116.
David Damanik 《Journal of Mathematical Analysis and Applications》2005,303(1):327-341
Following the Killip-Kiselev-Last method, we prove quantum dynamical upper bounds for discrete one-dimensional Schrödinger operators with Sturmian potentials. These bounds hold for sufficiently large coupling, almost every rotation number, and every phase. 相似文献
117.
Local four-dimensional tensor decomposition formulae for generic vectors and 2-tensors in spacetime, in terms of scalar and antisymmetric covariant tensor potentials, are studied within the framework of tensor distributions. Earlier first-order decompositions are extended to include the case of four-dimensional symmetric 2-tensors and new second-order decompositions are introduced. 相似文献
118.
We introduce the class of ordinal games with a potential, which are characterized by the absence of weak improvement cycles,
the same condition used by Voorneveld and Norde (1997) for ordinal potential games. 相似文献
119.
Nicolas Fournier 《Journal of Functional Analysis》2009,256(8):2542-2560
We consider the spatially homogeneous Landau equation of kinetic theory, and provide a differential inequality for the Wasserstein distance with quadratic cost between two solutions. We deduce some well-posedness results. The main difficulty is that this equation presents a singularity for small relative velocities. Our uniqueness result is the first one in the important case of soft potentials. Furthermore, it is almost optimal for a class of moderately soft potentials, that is for a moderate singularity. Indeed, in such a case, our result applies for initial conditions with finite mass, energy, and entropy. For the other moderately soft potentials, we assume additionally some moment conditions on the initial data. For very soft potentials, we obtain only a local (in time) well-posedness result, under some integrability conditions. Our proof is probabilistic, and uses a stochastic version of the Landau equation, in the spirit of Tanaka [H. Tanaka, Probabilistic treatment of the Boltzmann equation of Maxwellian molecules, Z. Wahrsch. Verw. Geb. 46 (1) (1978-1979) 67-105]. 相似文献
120.
A. E. Kramida M.-C. Buchet-Poulizac 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):265-276
All experimental data on Ne VII, including
previously unpublished beam-foil spectroscopy data, have been compiled and
critically evaluated. More than a hundred spectral lines have been newly
identified. For 40 transitions, the previous identifications have been
revised. These revisions resolved all existing contradictions between
previously published interpretations of the spectrum. An optimized level
scheme has been derived from the total list of observed lines. About a
hundred new energy levels have been found, including several highly excited
hydrogenic levels. Based on these newly determined levels, as well as on the
analysis of theoretical data, the ionization potential has been newly
determined with improved confidence.
Electronic supplementary material Online Material 相似文献