全文获取类型
收费全文 | 4080篇 |
免费 | 648篇 |
国内免费 | 419篇 |
专业分类
化学 | 509篇 |
晶体学 | 88篇 |
力学 | 344篇 |
综合类 | 49篇 |
数学 | 1776篇 |
物理学 | 2381篇 |
出版年
2024年 | 5篇 |
2023年 | 33篇 |
2022年 | 99篇 |
2021年 | 77篇 |
2020年 | 102篇 |
2019年 | 90篇 |
2018年 | 90篇 |
2017年 | 89篇 |
2016年 | 111篇 |
2015年 | 103篇 |
2014年 | 182篇 |
2013年 | 318篇 |
2012年 | 176篇 |
2011年 | 176篇 |
2010年 | 196篇 |
2009年 | 264篇 |
2008年 | 258篇 |
2007年 | 271篇 |
2006年 | 253篇 |
2005年 | 236篇 |
2004年 | 186篇 |
2003年 | 198篇 |
2002年 | 227篇 |
2001年 | 178篇 |
2000年 | 171篇 |
1999年 | 172篇 |
1998年 | 151篇 |
1997年 | 113篇 |
1996年 | 81篇 |
1995年 | 67篇 |
1994年 | 67篇 |
1993年 | 42篇 |
1992年 | 38篇 |
1991年 | 34篇 |
1990年 | 26篇 |
1989年 | 28篇 |
1988年 | 28篇 |
1987年 | 25篇 |
1986年 | 30篇 |
1985年 | 31篇 |
1984年 | 18篇 |
1983年 | 10篇 |
1982年 | 21篇 |
1981年 | 12篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 14篇 |
1976年 | 12篇 |
1972年 | 4篇 |
排序方式: 共有5147条查询结果,搜索用时 46 毫秒
981.
This paper studies the cascading failure on random networks and
scale-free networks by introducing the tolerance parameter of edge
based on the coupled map lattices methods. The whole work focuses on
investigating some indices including the number of failed edges,
dynamic edge tolerance capacity and the perturbation of edge. In
general, it assumes that the perturbation is attributed to the
normal distribution in adopted simulations. By investigating the
effectiveness of edge tolerance in scale-free and random networks,
it finds that the larger tolerance parameter λ can more
efficiently delay the cascading failure process for scale-free
networks than random networks. These results indicate that the
cascading failure process can be effectively controlled by
increasing the tolerance parameter λ. Moreover, the
simulations also show that, larger variance of perturbation can
easily trigger the cascading failures than the smaller one. This
study may be useful for evaluating efficiency of whole traffic
systems, and for alleviating cascading failure in such systems. 相似文献
982.
We use the Monte Carlo method to study an antiferromagnetical Ising spin
system on a centred honeycomb lattice, which is composed of two kinds
of 1/2 spin particles A and B. There exist two different bond
energies JA-A and JA-B in this lattice. Our
study is focused on how the ratio of JA-B to JA-A influences the critical behaviour of this system by analysing the physical quantities, such as the energy, the order parameter,
the specific heat, susceptibility, {etc} each as a function of temperature for a given ratio of JA-B to JA-A. Using these results together with the finite-size scaling method,
we obtain a phase diagram for the ratio JA-B / JA-A. This work is helpful for studying the phase transition
problem of crystals composed of compounds. 相似文献
983.
Lattice Boltzmann simulation of fluid flows in two-dimensional channel with complex geometries
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Boundary conditions (BCs) play an essential role in lattice
Boltzmann (LB) simulations. This paper investigates several most
commonly applied BCs by evaluating the relative L2-norm errors
of the LB simulations for two-dimensional (2-D) Poiseuille flow. It
is found that the relative L2-norm error resulting from FHML's
BC is smaller than that from other BCs as a whole. Then, based on
the FHML's BC, it formulates an LB model for simulating fluid flows
in 2-D channel with complex geometries. Afterwards, the flows
between two inclined plates, in a pulmonary blood vessel and in a
blood vessel with local expansion region, are simulated. The
numerical results are in good agreement with the analytical
predictions and clearly show that the model is effective. It is
expected that the model can be extended to simulate some real
biologic flows, such as blood flows in arteries, vessels with
stenosises, aneurysms and bifurcations, etc. 相似文献
984.
In this paper we study the existence and stability of two-dimensional discrete gap
breathers in a two-dimensional diatomic face-centered square lattice
consisting of alternating light and heavy atoms, with on-site
potential and coupling potential. This study is focused on
two-dimensional breathers with their frequency in the gap that
separates the acoustic and optical bands of the phonon spectrum. We
demonstrate the possibility of the existence of two-dimensional gap
breathers by using a numerical method. Six types of two-dimensional
gap breathers are obtained, i.e., symmetric, mirror-symmetric and
asymmetric, whether the center of the breather is on a light or a
heavy atom. The difference between one-dimensional discrete gap
breathers and two-dimensional discrete gap breathers is also
discussed. We use Aubry's theory to analyze the stability of
discrete gap breathers in the two-dimensional diatomic face-centered
square lattice. 相似文献
985.
Effects of periodic optical lattice potential on dark solitons in a Bose Einstein condensate
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper investigates the dynamics of dark solitons in a
Bose--Einstein condensate with a magnetic trap and an optical
lattice (OL) trap, and analyses the effects of the periodic OL
potential on the dynamics by applying the variational approach based
on the renormalized integrals of motion. The results show that the
dark soliton becomes only a standing-wave and free propagation
of the dark soliton is not possible when the periodic length of the
OL potential is approximately equal to the effective width of the
dark soliton. When the periodic length is very small or very large,
the effects of the OL potential on the dark soliton will be sharply
reduced. Finally, the numerical results confirm these theoretical
findings. 相似文献
986.
987.
CAN Bao-Xia CHEN Yin-Hua 《理论物理通讯》2007,48(4):734-736
Lattice wave of magnetized spherical dust in radio-frequency sheath with negative ions is investigated. The dispersion relation of two-dimensional hexagonal lattice horizontal wave and the influence of negative ions and magnetic field intensity on the wave are also investigated. The results show that for two-dimensional hexagonal horizontal lattice wave, negative ions reduce the wave frequency at the range of long-wavelength, whereas raising the wave frequency at the range of short-wavelength and magnetic field contributes to dropping the wave frequency a little. 相似文献
988.
WANG Deng-Long YANG Ru-Shu YANG You-Tian 《理论物理通讯》2007,48(5):917-920
Based on multiple scales method, we study the nonlinear properties of a new Fermi-Pasta-Ulam lattice model analytically. It is found that the lattice chain exhibits a novel nonlinear elementary excitation, i.e. a dark soliton. Moreover, the modulation depth of dark soliton is increasing as the anharmonic parameter increases. 相似文献
989.
A short‐range force constant model has been applied to investigate the Raman and the infrared wavenumbers in R2BaNiO5 (R = Y, Gd) in their orthorhombic phase of space group Immm. Calculations of zone‐center phonons are made with seven stretching and four bending force constants. The force constants are evaluated by fitting nine Raman and two infrared modes. Two Raman modes are reassigned on the basis of group theoretical calculations. The calculated Raman and infrared modes show good agreement with the observed values. The infrared values are assigned for the first time in these oxides. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
990.