全文获取类型
收费全文 | 387篇 |
免费 | 8篇 |
国内免费 | 5篇 |
专业分类
化学 | 227篇 |
力学 | 11篇 |
数学 | 44篇 |
物理学 | 118篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 11篇 |
2015年 | 7篇 |
2014年 | 11篇 |
2013年 | 16篇 |
2012年 | 15篇 |
2011年 | 23篇 |
2010年 | 10篇 |
2009年 | 15篇 |
2008年 | 30篇 |
2007年 | 24篇 |
2006年 | 28篇 |
2005年 | 24篇 |
2004年 | 16篇 |
2003年 | 13篇 |
2002年 | 15篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1957年 | 1篇 |
1948年 | 4篇 |
1941年 | 3篇 |
1937年 | 3篇 |
1930年 | 1篇 |
1929年 | 1篇 |
排序方式: 共有400条查询结果,搜索用时 15 毫秒
111.
We have investigated azimuthal spin-wave modes in magnetic vortex structures using time-resolved Kerr microscopy. Spatially resolved phase and amplitude spectra of ferromagnetic disks with diameters from 5 microm down to 500 nm reveal that the lowest order azimuthal spin-wave mode splits into a doublet as the disk size decreases. We demonstrate that the splitting is due to the coupling between spin waves and the gyrotropic motion of the vortex core. 相似文献
112.
113.
A streaming model (high field) analysis is given for the average energy for and the probability of electron-hole pair production in a semiconductor when a quadratically energy dependent impact ionization cross-section exists above a threshold energy and competes with a nonpolar optical phonon scattering mechanism. A power series expansion method and tabulated results are provided to treat the resulting probability integrals of the form ∫0∞xn exp {?(βx + x3)}dx. 相似文献
114.
115.
P. K. Anastasovski T. E. Bearden C. Ciubotariu W. T. Coffey L. B. Crowell G. J. Evans M. W. Evans R. Flower A. Labounsky B. Lehnert M. Mészáros P. R. Molnár S. Roy J. P. Vigier 《Foundations of Physics Letters》2002,15(2):179-187
By considering the irreducible representations of the Einstein group (the Lie group of general relativity), Sachs [1] has shown that the electromagnetic field tensor can be developed in terms of a metric q
, which is a set of four quaternion-valued components of four-vector. Using this method, it is shown that the electromagnetic field vanishes [1] in flat spacetime, and that electromagnetism in general is a non-Abelian field theory. In this paper the non-Abelian component of the field tensor is developed to show the presence of the B
(3) field of the O(3) electrodynamics, and the basic structure of O(3) electrodynamics is shown to be a sub-structure of general relativity as developed by Sachs. The extensive empirical evidence for both theories is summarized. 相似文献
116.
In this article we prove that the following NLS iu_t = u_{zz}-g|u|^{P-1}u,g > O, x, t > 0 with either Dirichlet or Robin boundary condition at x = 0 is well-posed. L^{p + 1} decay estimates, blow-up theorem and numerical results are also given. 相似文献
117.
Karen R. Maxcy Randy Smith Roger D. Willett Ashwani Vij 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(10):e454-e454
The title compound, [NiCl2(C6H8N2)2], contains centrosymmetric molecules with two phenylenediamine ligands coordinated in a bidentate fashion. The Ni—N distances are 2.088 (1) and 2.096 (1) Å, and the Ni—Cl distance of 2.4635 (4) Å. The plane of each phenylenediamine molecule makes a dihedral angle of 26.53 (7)° with the NiN4 plane. Extensive hydrogen bonding leads to distinct cleavage in the bc plane. 相似文献
118.
119.
Surface roughness can have a critical effect upon the splashing threshold and dynamics of a drop impacting on either a dry
or rough solid surface or one coated by a thin fluid film. As most coating applications and spray systems quickly evolve to
a state where the droplets impinge upon fluid deposited by preceding droplets, the combined contributions of surface roughness
and a pre-deposited thin liquid film of comparable thickness upon droplet impingement dynamics are examined. For comparison,
we include results for droplets impacting on a smooth, dry surface and a smooth surface wetted by a thin fluid film. The inclusion
of surface roughness considerably lowers the splashing threshold and alters the splashing dynamics such that differences in
fluid surface tensions between 20.1 and 72.8 dynes/cm or viscosities between 0.4 and 3.3 cP have little effect. 相似文献
120.
On the basis of empirical data, power-law boundary relations are formulated to delineate the splash and non-splash regions
on dry surfaces or thin films under isothermal conditions, using the Ohnesorge and Reynolds numbers. Approximation of the
relations permits cancellation of fundamental fluid physical constants to give simplified formulas which provide insight into
the governing parameters describing splashing and non-splashing behaviors. Thus, for a droplet impinging upon a dry solid
surface, the splash/non-splash border is well described by √Ca = 0.35. For a drop impinging upon a thin fluid film, the analytical
simplification yields a boundary described by √We = 20. For both expressions, values greater than the numerical value result
in splashing. 相似文献