全文获取类型
收费全文 | 2659篇 |
免费 | 400篇 |
国内免费 | 158篇 |
专业分类
化学 | 325篇 |
晶体学 | 6篇 |
力学 | 241篇 |
综合类 | 39篇 |
数学 | 1282篇 |
物理学 | 1324篇 |
出版年
2023年 | 19篇 |
2022年 | 43篇 |
2021年 | 56篇 |
2020年 | 62篇 |
2019年 | 57篇 |
2018年 | 75篇 |
2017年 | 70篇 |
2016年 | 72篇 |
2015年 | 73篇 |
2014年 | 123篇 |
2013年 | 220篇 |
2012年 | 148篇 |
2011年 | 150篇 |
2010年 | 134篇 |
2009年 | 177篇 |
2008年 | 188篇 |
2007年 | 165篇 |
2006年 | 154篇 |
2005年 | 138篇 |
2004年 | 106篇 |
2003年 | 108篇 |
2002年 | 114篇 |
2001年 | 80篇 |
2000年 | 89篇 |
1999年 | 80篇 |
1998年 | 50篇 |
1997年 | 63篇 |
1996年 | 48篇 |
1995年 | 35篇 |
1994年 | 28篇 |
1993年 | 32篇 |
1992年 | 34篇 |
1991年 | 33篇 |
1990年 | 36篇 |
1989年 | 21篇 |
1988年 | 22篇 |
1987年 | 30篇 |
1986年 | 13篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1973年 | 2篇 |
1971年 | 3篇 |
排序方式: 共有3217条查询结果,搜索用时 31 毫秒
911.
Let G = (V, E) be a primitive digraph. The vertex exponent of G at a vertex v ∈ V, denoted by expG(v), is the least integer p such that there is a v → u walk of length p for each u ∈ V. We choose to order the vertices of G in the k-point exponent of G and is denoted by expG(k), 1 ≤ k ≤ n. We define the k-point exponent set E(n, k) := {expG(k)| G = G(A) with A ∈ CSP(n)}, where CSP(n) is the set of all n × n central symmetric primitive matrices and G(A) is the associated graph of the matrix A. In this paper, we describe E(n,k) for all n, k with 1 ≤ k ≤ n except n ≡ 1(mod 2) and 1 ≤ k ≤ n - 4. We also characterize the extremal graphs when k = 1. 相似文献
912.
Aleš Nekvinda 《Journal of Mathematical Analysis and Applications》2008,337(2):1345-1365
We study general Lebesgue spaces with variable exponent p. It is known that the classes L and N of functions p are such that the Hardy-Littlewood maximal operator is bounded on them provided p∈L∩P. The class L governs local properties of p and N governs the behavior of p at infinity.In this paper we focus on the properties of p near infinity. We extend the class N to a collection D of functions p such that the Hardy-Littlewood maximal operator is bounded on the corresponding variable Lebesgue spaces provided p∈L∩D and the class D is essentially larger than N.Moreover, the condition p∈D is quite easily verifiable in the practice. 相似文献
913.
黄丽容 《应用泛函分析学报》2006,8(4):319-323
通过对偶变分方法证明了一个带Hardy项和临界非线性的非线性椭圆方程的非平凡解的存在性和多重性. 相似文献
914.
J. Chabrowski 《Annali di Matematica Pura ed Applicata》2007,186(4):703-719
In this paper we investigate the solvability of the nonlinear Neumann problem (1.1) with indefinite weight functions and a
critical Hardy–Sobolev nonlinearity. We examine the common effect of the shape of the graph of a weight function and the mean
curvature of the boundary on the existence of solutions of problem (1.1). We also investigate the regularity of solutions.
相似文献
915.
Eiichi Nakai 《数学学报(英文版)》2008,24(8):1243-1268
Let X = (X, d,μ) The purpose of this paper is to be a space of homogeneous type in the sense of Coifman and Weiss. generalize the definition of Hardy space H^P(X) and prove that the generalized Hardy spaces have the same property as H^P(X). Our definition includes a kind of Hardy- Orlicz spaces and a kind of Hardy spaces with variable exponent. The results are new even for the R^n case. Let (X, δ, μ) be the normalized space of (X, d, μ) in the sense of Macias and Segovia. We also study the relations of our function spaces for (X, d, μ) and (X, δ,μ). 相似文献
916.
We analyze self-similar solutions to a nonlinear fractional diffusion equation and fractional Burgers/Korteweg–deVries equation in one spatial variable. By using Lie-group scaling transformation, we determined the similarity solutions. After the introduction of the similarity variables, both problems are reduced to ordinary nonlinear fractional differential equations. In two special cases exact solutions to the ordinary fractional differential equation, which is derived from the diffusion equation, are presented. In several other cases the ordinary fractional differential equations are solved numerically, for several values of governing parameters. In formulating the numerical procedure, we use special representation of a fractional derivative that is recently obtained. 相似文献
917.
918.
上证综指分形特征研究 总被引:1,自引:0,他引:1
本文阐述了分形市场理论的基本思想和主要特征,运用重标极差(R/S)方法论对上证综指时间序列进行分形诊断,得出如下结论:①我国证券市场存在非周期循环,上证综指四种非周期循环的平均长度分别为858天、353天、246天和65天。②上证综指长周期Hurst指数值为0.561,市场具有“记忆”功能,信息对市场的影响具有持续性。③和西方市场相比,上证综指Hurst指数值较低,从而说明我国证券市场效率相对较低。 相似文献
919.
本文讨论了Ω上如下一类带临界增长的椭圆方程在拟超临界的Neumann边界条件下正解的存在性:-Div(| u |p-2 u) =λum up*-1,-| u |p-2 u ν=ψ(x)uq-1,x∈Ω,x∈Ω.这里Ω∈RN,(N≥3)是光滑有界区域, 1≤p < N,0< m < p-1,(N -1)pN - p= p*N-1 ≤q < p*,其中p* =NpN - p是W1,p(Ω)→Ls(Ω)的Sobolev临界指数,p*N-1 =(N -1)pN - p是W1,p(Ω)→Lt( Ω)的在(N-1)维流形上的临界指数,λ>0是一个正参数. 相似文献
920.
The measurements of partial production cross sections of the multiple helium projectile fragments emitted at 4.5 A GeV/c {}^{16}O-Em interactions are reported. We have studied the production rate of helium projectile fragments due to fragmentation of {}^{16}O ions and compared it with that obtained from different projectiles at various energies. The dependence of on the mass number of the incident beams is formulated. The multiplicity distributions of the helium fragments produced in {}^{16}O-Em interactions at different energies exhibit Koba-Nielson-Olesen (KNO) scaling. The correlation of helium projectile fragments and target fragments is also investigated and it is found that the average of target fragments is increased with the decrease of the number of helium fragments in peripheral interactions. 相似文献