全文获取类型
收费全文 | 6573篇 |
免费 | 841篇 |
国内免费 | 701篇 |
专业分类
化学 | 1348篇 |
晶体学 | 40篇 |
力学 | 396篇 |
综合类 | 168篇 |
数学 | 3722篇 |
物理学 | 2441篇 |
出版年
2024年 | 15篇 |
2023年 | 62篇 |
2022年 | 134篇 |
2021年 | 160篇 |
2020年 | 183篇 |
2019年 | 175篇 |
2018年 | 187篇 |
2017年 | 213篇 |
2016年 | 236篇 |
2015年 | 170篇 |
2014年 | 324篇 |
2013年 | 621篇 |
2012年 | 313篇 |
2011年 | 350篇 |
2010年 | 338篇 |
2009年 | 391篇 |
2008年 | 432篇 |
2007年 | 423篇 |
2006年 | 370篇 |
2005年 | 372篇 |
2004年 | 346篇 |
2003年 | 322篇 |
2002年 | 303篇 |
2001年 | 231篇 |
2000年 | 199篇 |
1999年 | 209篇 |
1998年 | 197篇 |
1997年 | 149篇 |
1996年 | 129篇 |
1995年 | 96篇 |
1994年 | 88篇 |
1993年 | 46篇 |
1992年 | 52篇 |
1991年 | 31篇 |
1990年 | 36篇 |
1989年 | 39篇 |
1988年 | 32篇 |
1987年 | 16篇 |
1986年 | 18篇 |
1985年 | 16篇 |
1984年 | 17篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 5篇 |
排序方式: 共有8115条查询结果,搜索用时 0 毫秒
991.
992.
993.
In this article we introduce the sequence spaces cI(M),c0I(M),mI(M) and m0I(M) using the Orlicz function M.We study some of the properties like solid,symmetric,sequence algebra,etc and prove some inclusion relations. 相似文献
994.
It is well-known that the eigenvalues of stochastic matrices lie in the unit circle and at least one of them has the value one. Let {1, r 2 , ··· , r N } be the eigenvalues of stochastic matrix X of size N × N . We will present in this paper a simple necessary and sufficient condition for X such that |r j | < 1, j = 2, ··· , N . Moreover, such condition can be very quickly examined by using some search algorithms from graph theory. 相似文献
995.
B.Yousefi 《数学物理学报(B辑英文版)》2011,31(1):68-72
This article derives the relation between universal interpolating sequences and some spectral properties of the multiplication operator by the independent variable z in case the underlying space is a Hilbert space of functions analytic on the open unit disk. 相似文献
996.
Given a connected graph G = (N, E) with node weights s∈? and nonnegative edge lengths, we study the following embedding problem related to an eigenvalue optimization problem over the second smallest eigenvalue of the (scaled) Laplacian of G: Find vi∈?|N|, i∈N so that distances between adjacent nodes do not exceed prescribed edge lengths, the weighted barycenter of all points is at the origin, and is maximized. In the case of a two‐dimensional optimal solution this corresponds to the equilibrium position of a quickly rotating net consisting of weighted mass points that are linked by massless cables of given lengths. We define the rotational dimension of G to be the minimal dimension k so that for all choices of lengths and weights an optimal solution can be found in ?k and show that this is a minor monotone graph parameter. We give forbidden minor characterizations up to rotational dimension 2 and prove that the rotational dimension is always bounded above by the tree‐width of G plus one. © 2010 Wiley Periodicals, Inc. J Graph Theory 66:283‐302, 2011 相似文献
997.
We introduce a solver and preconditioning technique based on Domain Decomposition and the Fast Diagonalization Method that can be applied to tensor product based discretizations of the steady convection–diffusion equation. The method is based on a Robin–Robin interface preconditioner coupled to a fast diagonalization solver which is used to efficiently eliminate the interior degrees of freedom and perform subsidiary subdomain solves. Using a spectral element discretization, we first apply our technique to constant wind problems, and then propose a means for applying the technique as a preconditioner for variable wind problems. We demonstrate that iteration counts are mildly dependent on changes in mesh size and convection strength. © 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2011 相似文献
998.
Huanmin Yao 《Numerical Methods for Partial Differential Equations》2011,27(4):867-886
In this article, an iterative method is proposed for solving nonlinear hyperbolic telegraph equation with an integral condition. Its exact solution is represented in the form of series in the reproducing kernel space. In the mean time, the n‐term approximation un(x, t) of the exact solution u(x, t) is obtained and is proved to converge to the exact solution. Moreover, the partial derivatives of un(x, t) are also convergent to the partial derivatives of u(x, t). Some numerical examples have been studied to demonstrate the accuracy of the present method. Results obtained by the method have been compared with the exact solution of each example and are found to be in good agreement with each other. © 2010 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 27: 867–886, 2011 相似文献
999.
Liu Y Yang D 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(1):213-218
The combined density functional theory (DFT) and time-dependent density functional theory (TDDFT) method was used to study the electronic spectral properties of different deprotonated forms of esculetin. By comparing the experimental absorption and fluorescence bands with the calculated electronic spectra, it is evidently demonstrated that the minor absorption and fluorescence bands observed at slightly longer wavelengths than the principal bands in experiments are predominantly from the de-H3 form of the esculetin monomer. Furthermore, we clarified the relationship between electronic spectral shifts and electronic excited-state intramolecular hydrogen bonding changes: the strengthening of intramolecular hydrogen bond can induce an electronic spectral blueshift while the intramolecular hydrogen bond weakening can result in an electronic spectral redshift. 相似文献
1000.
Roswitha Hofer 《Discrete Mathematics》2011,(16):1724
Newman proved for the classical Thue–Morse sequence, ((−1)s(n))n≥0, that for all N∈N with real constants satisfying c2>c1>0 and λ=log3/log4. Coquet improved this result and deduced , where F(x) is a nowhere-differentiable, continuous function with period 1 and η(N)∈{−1,0,1}. In this paper we obtain for the weighted version of the Thue–Morse sequence that for the sum a Coquet-type formula exists for every r∈{0,1,2} if and only if the sequence of weights is eventually periodic. From the specific Coquet-type formulas we derive parts of the weak Newman-type results that were recently obtained by Larcher and Zellinger. 相似文献