全文获取类型
收费全文 | 20934篇 |
免费 | 2274篇 |
国内免费 | 2108篇 |
专业分类
化学 | 2406篇 |
晶体学 | 34篇 |
力学 | 1913篇 |
综合类 | 510篇 |
数学 | 14247篇 |
物理学 | 6206篇 |
出版年
2024年 | 30篇 |
2023年 | 182篇 |
2022年 | 343篇 |
2021年 | 380篇 |
2020年 | 446篇 |
2019年 | 458篇 |
2018年 | 471篇 |
2017年 | 608篇 |
2016年 | 673篇 |
2015年 | 534篇 |
2014年 | 1066篇 |
2013年 | 1346篇 |
2012年 | 1081篇 |
2011年 | 1316篇 |
2010年 | 1164篇 |
2009年 | 1440篇 |
2008年 | 1413篇 |
2007年 | 1495篇 |
2006年 | 1339篇 |
2005年 | 1291篇 |
2004年 | 1046篇 |
2003年 | 943篇 |
2002年 | 800篇 |
2001年 | 745篇 |
2000年 | 674篇 |
1999年 | 596篇 |
1998年 | 540篇 |
1997年 | 503篇 |
1996年 | 363篇 |
1995年 | 291篇 |
1994年 | 247篇 |
1993年 | 183篇 |
1992年 | 157篇 |
1991年 | 126篇 |
1990年 | 139篇 |
1989年 | 94篇 |
1988年 | 89篇 |
1987年 | 76篇 |
1986年 | 68篇 |
1985年 | 81篇 |
1984年 | 68篇 |
1983年 | 46篇 |
1982年 | 66篇 |
1981年 | 59篇 |
1980年 | 38篇 |
1979年 | 34篇 |
1978年 | 30篇 |
1977年 | 27篇 |
1976年 | 31篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
1.
A.-S. F. Obada M. Darwish H. H. Salah 《International Journal of Theoretical Physics》2002,41(9):1755-1768
In this paper a new state called odd-excited binomial state (OEBS) is introduced. It interpolates between the odd number state and the odd-excited coherent state. We discuss some statistical properties, such as the Glauber second-order correlation function and squeezing phenomenon (normal and amplitude-squared squeezing) for this state. The quasiprobability distribution functions (Husimi Q-function and Wigner W-function) are also examined. 相似文献
2.
A. Mielke 《Journal of statistical physics》1991,62(3-4):509-528
The magnetic properties of the one-dimensional Hubbard model with a hardcore interaction on a ring (periodic boundary conditions) are investigated. At finite temperatures it is shown to behave up to exponentially small corrections as a pure paramagnet. An explicit expression for the ground-state degeneracies is derived. The eigenstates of this model are used to perform a perlurbational treatment for large but finite interactions. In first order inU
1 an effective Hamiltonian for the one-dimensional Hubbard model is derived. It is the Hamiltonian of the one-dimensional Hcisenberg model with antiferromagnetic couplings between nearest neighbor spins. An asymptotic expansion for the ground-state energy is given. The results are valid for arbitrary densities of electrons. 相似文献
3.
Under idealized conditions, electroconvection in a nematic liquid crystal sets in at a well-defined threshold of the driving ac voltage. Fluctuating convection rolls of a small amplitude below that threshold have been observed recently. The measurement of the amplitude of these fluctuations is described in detail in this paper. It is based on averaging the light intensity signals using the structure function and a quantitative analysis of the light deflection. 相似文献
4.
对求解非线性方程方法的探索 总被引:2,自引:0,他引:2
BaiCL在2001年提出了双曲函数法,并把解设成具体的双曲函数,即sinhw和coshw的线性组合.本文把解设成是由2个函数f(ξ)和g(ξ)组成的线性组合,它们可以有多种取法,从而使方程更直接、更有效.借助数学软件Maple,用改进后的方法和吴文俊消元法,求解Bai C L文中的一个例子,获得了包含Bai文结果在内的更为丰富、精确的行波解. 相似文献
5.
证明了当超越亚纯函数的级小于1时,其Norel例外值最多只有一个.由于存在任何级的整函数,因此一个例外值总可达到,故所得结果不能再改进。 相似文献
6.
In this paper, we give the following dominated theorem: Let φ(g) ∈ L1(G//K),φε(t)=ε> 0, and the least radical decreasing dominatedfunction φ(t) = sup |φ(y)| ∈L1(G//K). If shtφ(t) is monotonically decreasingon (0, ∞), then for any f∈L1loc(G//K) , the following inequality holds:sup |φε * f(x)| ≤ Cmf(x),where mf(x) is the Hardy-Littlewood maximal function of f, and C = ||φ||1.An application of this dominated theorem is also given. 相似文献
7.
Anna L. Mazzucato 《Transactions of the American Mathematical Society》2003,355(4):1297-1364
This paper is devoted to the analysis of function spaces modeled on Besov spaces and their applications to non-linear partial differential equations, with emphasis on the incompressible, isotropic Navier-Stokes system and semi-linear heat equations. Specifically, we consider the class, introduced by Hideo Kozono and Masao Yamazaki, of Besov spaces based on Morrey spaces, which we call Besov-Morrey or BM spaces. We obtain equivalent representations in terms of the Weierstrass semigroup and wavelets, and various embeddings in classical spaces. We then establish pseudo-differential and para-differential estimates. Our results cover non-regular and exotic symbols. Although the heat semigroup is not strongly continuous on Morrey spaces, we show that its action defines an equivalent norm. In particular, homogeneous BM spaces belong to a larger class constructed by Grzegorz Karch to analyze scaling in parabolic equations. We compare Karch's results with those of Kozono and Yamazaki and generalize them by obtaining short-time existence and uniqueness of solutions for arbitrary data with subcritical regularity. We exploit pseudo-differential calculus to extend the analysis to compact, smooth, boundaryless, Riemannian manifolds. BM spaces are defined by means of partitions of unity and coordinate patches, and intrinsically in terms of functions of the Laplace operator.
8.
We present a practical polynomial-time algorithm for computing the
zeta function of a Kummer curve over a finite field of small
characteristic. Such algorithms have recently been obtained using a
method of Kedlaya based upon Monsky–Washnitzer cohomology, and are of
interest in cryptography. We take a different approach.
The problem is reduced to that of computing the L-function
of a multiplicative character sum. This latter task is achieved via a
cohomological formula based upon the work of Dwork and Reich. We show,
however, that our method and that of Kedlaya are very closely related.Dedicated to the memory of Gian-Carlo Rota 相似文献
9.
The paper presents a new formulation of the integral boundary element method (BEM) using subdomain technique. A continuous approximation of the function and the function derivative in the direction normal to the boundary element (further ‘normal flux’) is introduced for solving the general form of a parabolic diffusion‐convective equation. Double nodes for normal flux approximation are used. The gradient continuity is required at the interior subdomain corners where compatibility and equilibrium interface conditions are prescribed. The obtained system matrix with more equations than unknowns is solved using the fast iterative linear least squares based solver. The robustness and stability of the developed formulation is shown on the cases of a backward‐facing step flow and a square‐driven cavity flow up to the Reynolds number value 50 000. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
10.