全文获取类型
收费全文 | 2373篇 |
免费 | 210篇 |
国内免费 | 382篇 |
专业分类
化学 | 197篇 |
晶体学 | 9篇 |
力学 | 214篇 |
综合类 | 52篇 |
数学 | 1946篇 |
物理学 | 547篇 |
出版年
2024年 | 8篇 |
2023年 | 21篇 |
2022年 | 45篇 |
2021年 | 50篇 |
2020年 | 53篇 |
2019年 | 65篇 |
2018年 | 62篇 |
2017年 | 68篇 |
2016年 | 55篇 |
2015年 | 48篇 |
2014年 | 83篇 |
2013年 | 333篇 |
2012年 | 80篇 |
2011年 | 113篇 |
2010年 | 94篇 |
2009年 | 108篇 |
2008年 | 164篇 |
2007年 | 159篇 |
2006年 | 152篇 |
2005年 | 106篇 |
2004年 | 113篇 |
2003年 | 124篇 |
2002年 | 113篇 |
2001年 | 107篇 |
2000年 | 93篇 |
1999年 | 89篇 |
1998年 | 95篇 |
1997年 | 67篇 |
1996年 | 58篇 |
1995年 | 47篇 |
1994年 | 43篇 |
1993年 | 22篇 |
1992年 | 17篇 |
1991年 | 16篇 |
1990年 | 20篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 4篇 |
1984年 | 12篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1972年 | 1篇 |
1971年 | 2篇 |
1936年 | 2篇 |
排序方式: 共有2965条查询结果,搜索用时 93 毫秒
851.
Uwe Nagel 《Transactions of the American Mathematical Society》2005,357(9):3585-3603
Castelnuovo-Mumford regularity and any extended degree function can be thought of as complexity measures for the structure of finitely generated graded modules. A recent result of Doering, Gunston, and Vasconcelos shows that both can be compared in the case of a graded algebra. We extend this result to modules and analyze when the estimate is in fact an equality. A complete classification is obtained if we choose as extended degree the homological or the smallest extended degree. The corresponding algebras are characterized in three ways: by relations among the algebra generators, by using generic initial ideals, and by their Hilbert series.
852.
A quasi-geostrophic intermediate complexity model of the mid-latitude atmospheric circulation is considered, featuring simplified baroclinic conversion and barotropic convergence processes. The model undergoes baroclinic forcing towards a given latitudinal temperature profile controlled by the forced equator-to-pole temperature difference TE. As TE increases, a transition takes place from a stationary regime-Hadley equilibrium-to a periodic regime, and eventually to a chaotic regime where evolution takes place on a strange attractor. The attractor dimension, metric entropy, and bounding box volume in phase space have a smooth dependence on TE, which results in power-law scaling properties. Power-law scalings with respect to TE are detected also for the statistical properties of global physical observables — the total energy of the system and the averaged zonal wind. The scaling laws, which constitute the main novel result of the present work, can be thought to result from the presence of a statistical process of baroclinic adjustment, which tends to decrease the equator-to-pole temperature difference and determines the properties of the attractor of the system. The self-similarity could be of great help in setting up a theory for the overall statistical properties of the general circulation of the atmosphere and in guiding-on a heuristic basis-both data analysis and realistic simulations, going beyond the unsatisfactory mean field theories and brute force approaches. A leading example for this would be the possibility of estimating the sensitivity of the output of the system with respect to changes in the parameters. 相似文献
853.
Duan-Ming Zhang Zhi-Yuan Chen Yan-Ping Yin Rui Li Xiang-Ying Su Wen-Jing Yang Ming-Tao Huang Hong-Ying Zhu Ling Zhang 《Physica A》2007
A one-dimensional dynamic model of polydisperse granular mixture with a power-law size distribution is presented, in which the particles are subject to inelastic mutual collisions and driven by Gaussian white noise. The particle size distribution of the mixture has the fractal characteristic, and a fractal dimension D as a measurement of the inhomogeneity of the particle size distribution is introduced. We define the global granular temperature and the kinetic pressure of the mixture, and obtain their expressions. By molecular dynamics simulations, we have mainly investigated how the inhomogeneity of the particle size distribution and the inelasticity of collisions influence the steady-state dynamic properties of the system, focusing on the global granular temperature, kinetic pressure, velocity distribution and distribution of interparticle spacing. Some novel results are found that, with the increase of the fractal dimension D, the global granular temperature and the kinetic pressure decrease, the velocity distribution deviates more obviously from the Gaussian one and the particles cluster more pronouncedly at the same value of the restitution coefficient e (0<e<1). On the other hand, as the restitution coefficient e decreases, the dynamic behavior has the similar evolution as above at the fixed fractal dimension D. The dynamic behavior changing with e and D is, respectively, presented. 相似文献
854.
855.
856.
857.
858.
We prove the existence of real numbers badly approximated by rational fractions whose denominators form a sublacunar sequence. For example, for the ascending sequence s
n
, n = 1, 2, 3, ..., generated by the ordered numbers of the form 2i3j, i, j = 1, 2, 3, ..., we prove that the set of real numbers α such that inf
n∈ℕ
n‖s
n
α‖ > 0 is a set of Hausdorff dimension 1. The divergence of the series
implies that the Lebesgue measure of those numbers is zero.__________Translated from Matematicheskie Zametki, vol. 77, no. 6, 2005, pp. 803–813.Original Russian Text Copyright ©2005 by R. K. Akhunzhanov, N. G. Moshchevitin. 相似文献
859.
860.
Klaus?FleischmannEmail author Vladimir?A.?Vatutin 《Journal of Theoretical Probability》2005,18(4):719-755
Consider a system of particles which move in Rd according to a symmetric α-stable motion, have a lifetime distribution of finite mean, and branch with an offspring law of index 1+β. In case of the critical dimension d=α/β the phenomenon of multi-scale clustering occurs. This is expressed in an fdd scaling limit theorem, where initially we start
with an increasing localized population or with an increasing homogeneous Poissonian population. The limit state is uniform,
but its intensity varies in line with the scaling index according to a continuous-state branching process of index 1+β. Our result generalizes the case α=2 of Brownian particles of Klenke (1998), where p.d.e. methods had been used which are not available in the present setting.
Supported in part by the DFG.
Supported in part by the grants RFBR 02-01-00266 and Russian Scientific School 1758.2003.1. 相似文献