全文获取类型
收费全文 | 19927篇 |
免费 | 2212篇 |
国内免费 | 2037篇 |
专业分类
化学 | 2250篇 |
晶体学 | 30篇 |
力学 | 1755篇 |
综合类 | 502篇 |
数学 | 13584篇 |
物理学 | 6055篇 |
出版年
2024年 | 25篇 |
2023年 | 166篇 |
2022年 | 329篇 |
2021年 | 358篇 |
2020年 | 414篇 |
2019年 | 422篇 |
2018年 | 444篇 |
2017年 | 575篇 |
2016年 | 644篇 |
2015年 | 500篇 |
2014年 | 1012篇 |
2013年 | 1285篇 |
2012年 | 1039篇 |
2011年 | 1261篇 |
2010年 | 1118篇 |
2009年 | 1376篇 |
2008年 | 1342篇 |
2007年 | 1432篇 |
2006年 | 1282篇 |
2005年 | 1225篇 |
2004年 | 1004篇 |
2003年 | 913篇 |
2002年 | 767篇 |
2001年 | 711篇 |
2000年 | 654篇 |
1999年 | 561篇 |
1998年 | 508篇 |
1997年 | 478篇 |
1996年 | 347篇 |
1995年 | 283篇 |
1994年 | 236篇 |
1993年 | 180篇 |
1992年 | 153篇 |
1991年 | 125篇 |
1990年 | 136篇 |
1989年 | 91篇 |
1988年 | 85篇 |
1987年 | 75篇 |
1986年 | 67篇 |
1985年 | 81篇 |
1984年 | 66篇 |
1983年 | 46篇 |
1982年 | 63篇 |
1981年 | 59篇 |
1980年 | 38篇 |
1979年 | 34篇 |
1978年 | 30篇 |
1977年 | 26篇 |
1976年 | 30篇 |
1973年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
In this paper, we give a convergence theorem and error estimates for an iteration method under new Kantorovitch-Ostrowski type condition using the information of higher derivatives at initial points. Compared with the corresponding study in [3],the convergence determination is established under one global condition, instead of two , on the function. 相似文献
132.
Experiments employing photoreflectance spectroscopy have uncovered band bending due to electrically active defects at the Si(1 1 1)–SiO2 interface after sub-keV Ar+ ion bombardment. The band bending of about 0.5 eV resembles that for Si(1 0 0)–SiO2, and both interfaces exhibit two kinetic regimes for the evolution of band bending upon annealing due to defects healing. The healing takes place about an order of magnitude more quickly at the (1 1 1) interface, however, probably because of less fully saturated bonding and higher compressive stress. 相似文献
133.
134.
Using recursive variants of Baire notions of nowhere dense and meagre sets we study the topological size of speedable and infinitely often speedable functions in a machine-independent framework. We show that the set of speedable functions is not “small” whereas the set of infinitely often speedable functions is “large”. In this way we offer partial answers to a question in [4]. 相似文献
135.
灰色Verhulst模型的样条插值函数的残差修正 总被引:4,自引:0,他引:4
本用样条函数对灰色Verhulst模型的残差序列进行插值拟合,然后作用于二阶线性微分方程,并以此修正原模型,得到一种新的预测模型的数值解,提高了拟合的精确度。 相似文献
136.
Cristinel Mortici 《Czechoslovak Mathematical Journal》2005,55(3):709-718
In this paper we give some new results concerning solvability of the 1-dimensional differential equation y′ = f(x, y) with initial conditions. We study the basic theorem due to Picard. First we prove that the existence and uniqueness result
remains true if f is a Lipschitz function with respect to the first argument. In the second part we give a contractive method for the proof
of Picard theorem. These considerations allow us to develop two new methods for finding an approximation sequence for the
solution. Finally, some applications are given. 相似文献
137.
138.
Wu Shengjian 《数学年刊B辑(英文版)》1994,15(4):453-462
Suppose that f(z)is a meromorphic function of order λ(0<λ<+∞)and of lower order μ in the plane.Let ρ be a positive number such that μ≤ρ≤λ.(1)If f^(l)(z)(0≤l<+∞)has p(1≤p<+∞)finite nonzero deficient valnes αi(i=1,…,p)with deficiencies δ(αi,f^(l)),then f(z)has a (0,∞)accumulative line of order ≥ρin any angular domain whose vertex is at the origin and whose magnitude is larger than max(π/ρ,2π-4/ρ ∑i=1^p arcsin √δ(αi,f^(l))/2).(2)If f(z) has only p(0<p<+∞)(0,∞),accumulative lines of order≥ρ:arg z=θk(0≤θ1<θ2<…<θp<2π,θp+1=θ1+2π),then λ≤π/ω,where ω=min I≤k≤p(θk+1-θk),provided that f^(l)(z)(0≤l<+∞)has a finite nonzero deficient value. 相似文献
139.
B.J. Stoyanov R.A. Farrell J.F. Bird 《Journal of Computational and Applied Mathematics》1994,50(1-3):533-543
Asymptotic expansions of certain finite and infinite integrals involving products of two Bessel functions of the first kind are obtained by using the generalized hypergeometric and Meijer functions. The Bessel functions involved are of arbitrary (generally different) orders, but of the same argument containing a parameter which tends to infinity. These types of integrals arise in various contexts, including wave scattering and crystallography, and are of general mathematical interest being related to the Riemann—Liouville and Hankel integrals. The results complete the asymptotic expansions derived previously by two different methods — a straightforward approach and the Mellin-transform technique. These asymptotic expansions supply practical algorithms for computing the integrals. The leading terms explicitly provide valuable analytical insight into the high-frequency behavior of the solutions to the wave-scattering problems. 相似文献
140.
A filled function with adjustable parameters is suggested in this paper for finding a global minimum point of a general class of nonlinear programming problems with a bounded and closed domain. This function has two adjustable parameters. We will discuss the properties of the proposed filled function. Conditions on this function and on the values of parameters are given so that the constructed function has the desired properties of traditional filled function. 相似文献