全文获取类型
收费全文 | 3968篇 |
免费 | 373篇 |
国内免费 | 78篇 |
专业分类
化学 | 99篇 |
晶体学 | 7篇 |
力学 | 1315篇 |
综合类 | 19篇 |
数学 | 824篇 |
物理学 | 2155篇 |
出版年
2024年 | 19篇 |
2023年 | 43篇 |
2022年 | 43篇 |
2021年 | 61篇 |
2020年 | 146篇 |
2019年 | 135篇 |
2018年 | 90篇 |
2017年 | 113篇 |
2016年 | 87篇 |
2015年 | 121篇 |
2014年 | 198篇 |
2013年 | 232篇 |
2012年 | 148篇 |
2011年 | 239篇 |
2010年 | 179篇 |
2009年 | 222篇 |
2008年 | 270篇 |
2007年 | 226篇 |
2006年 | 220篇 |
2005年 | 173篇 |
2004年 | 166篇 |
2003年 | 173篇 |
2002年 | 150篇 |
2001年 | 108篇 |
2000年 | 107篇 |
1999年 | 78篇 |
1998年 | 89篇 |
1997年 | 72篇 |
1996年 | 68篇 |
1995年 | 52篇 |
1994年 | 42篇 |
1993年 | 46篇 |
1992年 | 40篇 |
1991年 | 48篇 |
1990年 | 23篇 |
1989年 | 27篇 |
1988年 | 22篇 |
1987年 | 20篇 |
1986年 | 18篇 |
1985年 | 26篇 |
1984年 | 18篇 |
1983年 | 6篇 |
1982年 | 17篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 6篇 |
1971年 | 2篇 |
排序方式: 共有4419条查询结果,搜索用时 15 毫秒
51.
52.
An improved class of Boussinesq systems of an arbitrary order using a wave surface elevation and velocity potential formulation is derived. Dissipative effects and wave generation due to a time‐dependent varying seabed are included. Thus, high‐order source functions are considered. For the reduction of the system order and maintenance of some dispersive characteristics of the higher‐order models, an extra O(μ2n+2) term (n ∈ ?) is included in the velocity potential expansion. We introduce a nonlocal continuous/discontinuous Galerkin FEM with inner penalty terms to calculate the numerical solutions of the improved fourth‐order models. The discretization of the spatial variables is made using continuous P2 Lagrange elements. A predictor‐corrector scheme with an initialization given by an explicit Runge–Kutta method is also used for the time‐variable integration. Moreover, a CFL‐type condition is deduced for the linear problem with a constant bathymetry. To demonstrate the applicability of the model, we considered several test cases. Improved stability is achieved. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
53.
We study the propagation of anisotropic sound and shock waves in dipolar Bose-Einstein condensate in three dimensions (3D) as well as in quasi-two (2D, disk shape) and quasi-one (1D, cigar shape) dimensions using the mean-field approach. In 3D, the propagation of sound and shock waves are distinct in directions parallel and perpendicular to dipole axis with the appearance of instability above a critical value corresponding to attraction. Similar instability appears in 1D and not in 2D. The numerical anisotropic Mach angle agrees with theoretical prediction. The numerical sound velocity in all cases agrees with that calculated from Bogoliubov theory. A movie of the anisotropic wave propagation in a dipolar condensate is made available as supplementary material. 相似文献
54.
Luis G. MacDowell Jorge Benet Nebil A. Katcho Jose M.G. Palanco 《Advances in colloid and interface science》2014
In this paper we review simulation and experimental studies of thermal capillary wave fluctuations as an ideal means for probing the underlying disjoining pressure and surface tensions, and more generally, fine details of the Interfacial Hamiltonian Model. We discuss recent simulation results that reveal a film-height-dependent surface tension not accounted for in the classical Interfacial Hamiltonian Model. We show how this observation may be explained bottom-up from sound principles of statistical thermodynamics and discuss some of its implications. 相似文献
55.
56.
A new exactly solvable ()-dimensional complex nonlinear wave equation exhibiting rich analytic properties has been introduced. A rogue wave (RW), localized in space–time like Peregrine RW solution, though richer due to the presence of free parameters is discovered. This freedom allows to regulate amplitude and width of the RW as needed. The proposed equation allows also an intriguing topology changing accelerated dark soliton solution in spite of constant coefficients in the equation. 相似文献
57.
58.
《International Journal of Solids and Structures》2014,51(25-26):4452-4461
This paper brings a comparative analysis between dynamic models of couple-stress elastic materials and structured Rayleigh beams on a Winkler foundation. Although physical phenomena have different physical origins, the underlying equations appear to be similar, and hence mathematical models have a lot in common. In the present work, our main focus is on the analysis of dispersive waves, band-gaps and localised waveforms in structured Rayleigh beams. The Rayleigh beam theory includes the effects of rotational inertia which are neglected in the Euler–Bernoulli beam theory. This makes the approach applicable to higher frequency regimes. Special attention is given to waves in pre-stressed Rayleigh beams on elastic foundations. 相似文献
59.
This paper presents a method of the measurement of the optical absorption coefficient of the Ar8+ ions implanted layers in the p-type silicon substrate. The absorption coefficient is calculated using a value of the attenuation of amplitudes of a photothermal radiometry (PTR) and/or a modulation free carrier absorption (MFCA) signals and the implanted layer thickness calculated by means of the TRIM program. The proposed method can be used to indicate the amorphization of the ions implanted layers. 相似文献
60.
Eugene Kazantsev 《国际流体数值方法杂志》2011,65(10):1231-1259
A variational data assimilation technique applied to the identification of the optimal discretization of interpolation operators and derivatives in the nodes adjacent to the boundary of the domain is discussed in frames of the linear shallow water model. The advantage of controlling the discretization of operators near the boundary rather than boundary conditions is shown. Assimilating data that have been produced by the same model on a finer grid, in a model on a coarse grid, we have shown that optimal discretization allows us to correct such errors of the numerical scheme as under‐resolved boundary layer and wrong wave velocity. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献