全文获取类型
收费全文 | 35000篇 |
免费 | 5180篇 |
国内免费 | 4572篇 |
专业分类
化学 | 11462篇 |
晶体学 | 205篇 |
力学 | 3095篇 |
综合类 | 637篇 |
数学 | 14871篇 |
物理学 | 14482篇 |
出版年
2024年 | 73篇 |
2023年 | 359篇 |
2022年 | 598篇 |
2021年 | 879篇 |
2020年 | 1097篇 |
2019年 | 951篇 |
2018年 | 963篇 |
2017年 | 1146篇 |
2016年 | 1336篇 |
2015年 | 1117篇 |
2014年 | 1874篇 |
2013年 | 2620篇 |
2012年 | 1953篇 |
2011年 | 2267篇 |
2010年 | 1994篇 |
2009年 | 2442篇 |
2008年 | 2406篇 |
2007年 | 2536篇 |
2006年 | 2330篇 |
2005年 | 2052篇 |
2004年 | 1757篇 |
2003年 | 1614篇 |
2002年 | 1336篇 |
2001年 | 1210篇 |
2000年 | 1140篇 |
1999年 | 999篇 |
1998年 | 886篇 |
1997年 | 772篇 |
1996年 | 598篇 |
1995年 | 508篇 |
1994年 | 423篇 |
1993年 | 322篇 |
1992年 | 272篇 |
1991年 | 251篇 |
1990年 | 216篇 |
1989年 | 171篇 |
1988年 | 155篇 |
1987年 | 136篇 |
1986年 | 125篇 |
1985年 | 133篇 |
1984年 | 105篇 |
1983年 | 66篇 |
1982年 | 94篇 |
1981年 | 93篇 |
1980年 | 66篇 |
1979年 | 61篇 |
1978年 | 42篇 |
1977年 | 46篇 |
1976年 | 42篇 |
1973年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
I. P. Kayumov 《Mathematical Notes》2005,78(3-4):498-502
In this paper, we prove Brennan's conjecture for conformal mappings f of the disk {z : | z| < 1} assuming that the Taylor coefficients of the function log(zf′(z)/f(z)) at zero are nonnegative. We also obtain inequalities for the integral means over the circle |z| = r of the squared modulus of the function zf′(z)/f(z). 相似文献
102.
提出了一种比较系统的求解非线性发展方程精确解的新方法, 即试探方程法. 以一个带5阶 导数项的非线性发展方程为例, 利用试探方程法化成初等积分形式,再利用三阶多项式的完 全判别系统求解,由此求得的精确解包括有理函数型解, 孤波解, 三角函数型周期解, 多项 式型Jacobi椭圆函数周期解和分式型Jacobi椭圆函数周期解
关键词:
试探方程法
非线性发展方程
孤波解
Jacobi椭圆函数
周期解 相似文献
103.
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.
104.
林正炎 《数学物理学报(B辑英文版)》2003,23(3)
Let {X_n, n≥1} be a strictly stationary sequence of random variables, whichare either associated or negatively associated, f(·) be their common density. In this paper,the author shows a central limit theorem for a kernel estimate of f(·) under certain regularconditions. 相似文献
105.
Chin-Tsang Chiang Mei-Cheng Wang 《Annals of the Institute of Statistical Mathematics》2004,56(1):87-100
This paper proposes kernel estimation of the occurrence rate function for recurrent event data with informative censoring.
An informative censoring model is considered with assumptions made on the joint distribution of the recurrent event process
and the censoring time without modeling the censoring distribution. Under the validity of the informative censoring model,
we also show that an estimator based on the assumption of independent censoring becomes inappropriate and is generally asymptotically
biased. To investigate the asymptotic properties of the proposed estimator, the explicit form of its asymptotic mean squared
risk and the asymptotic normality are derived. Meanwhile, the empirical consistent smoothing estimator for the variance function
of the estimator is suggested. The performance of the estimators are also studied through Monte Carlo simulations. An epidemiological
example of intravenous drug user data is used to show the influence of informative censoring in the estimation of the occurrence
rate functions for inpatient cares over time. 相似文献
106.
袁文俊 《数学物理学报(A辑)》2003,23(2):224-230
该文考虑具有控制系数 A\-0 和系数仅有有限个极点的高阶线性齐次微分方程(1.1)。得到了一个复振荡结果,该结果是J. K. Langley[11]等作者在整系数下相应结果的推广。 相似文献
107.
A locally convex space is said to be a Gateaux differentiability space (GDS)provided every continuous convex function defined on a nonempty convex open subset D of the space is densely Gateaux differentiable in D.This paper shows that the product of a GDS and a family of separable Frechet spaces is a GDS,and that the product of a GDS and an arbitrary locally convex space endowed with the weak topology is a GDS. 相似文献
108.
109.
《Tetrahedron》2003,59(34):6415-6422
The Nuclear Independent Chemical Shift of each ring, as a criterion of aromaticity, is used to explain the stability order of benzopyrrole, benzofuran and benzothiophene, and their isomers. The results indicate that the benzene ring is aromatic in all the systems. The five-membered rings of benzopyrrole, benzofuran and benzothiophene are also aromatic, whereas those of isobenzopyrrole, isobenzofuran and isobenzothiophene are non-aromatic. This could be an explanation of the stability of the former molecules. The molecular orbitals and the condensed Fukui functions derived from the electronic structure calculations are also reported. These reactivity indices explain the expected electrophilic substitution of these compounds. The theoretical structure, ionization energies, order of aromaticity, stability and reactivity are in good agreement with the experimental results. The usefulness of this approach to determine the reactivity is discussed since their stability and reactivity may be understood. The reactivity indices are useful to explain and confirm the experimental information, and for molecules with unknown reactive behavior, this approach could help to predict some of the reactions. 相似文献
110.
本文考虑广义C-R组^[1](H)的解f=u iv jw∈C^2的一些性质,提出与之相关的两个边值问题,用积分方程方法和调和函数性质证明了边值问题解的存在唯一性,并写出解的积分表达式. 相似文献