全文获取类型
收费全文 | 642篇 |
免费 | 15篇 |
国内免费 | 18篇 |
专业分类
化学 | 285篇 |
晶体学 | 4篇 |
力学 | 4篇 |
数学 | 310篇 |
物理学 | 72篇 |
出版年
2023年 | 3篇 |
2022年 | 15篇 |
2021年 | 20篇 |
2020年 | 12篇 |
2019年 | 18篇 |
2018年 | 10篇 |
2017年 | 10篇 |
2016年 | 20篇 |
2015年 | 21篇 |
2014年 | 23篇 |
2013年 | 48篇 |
2012年 | 50篇 |
2011年 | 48篇 |
2010年 | 37篇 |
2009年 | 34篇 |
2008年 | 46篇 |
2007年 | 40篇 |
2006年 | 37篇 |
2005年 | 23篇 |
2004年 | 25篇 |
2003年 | 23篇 |
2002年 | 13篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1971年 | 1篇 |
排序方式: 共有675条查询结果,搜索用时 15 毫秒
621.
Recently, Girstmair and Schoissengeier studied the asymptotic behavior of the arithmetic mean of Dedekind sums
\frac1j(N) ? 0 £ m < Ngcd(m,N)=1 |S(m,N)|\frac{1}{\varphi(N)} \sum_{\mathop{\mathop{ 0 \le m< N}}\limits_{\gcd(m,N)=1}} \vert S(m,N)\vert
, as N → ∞. In this paper we consider the arithmetic mean of weighted differences of Dedekind sums in the form
Ah(Q)=\frac1?\fracaq ? FQh(\fracaq) ×?\fracaq ? FQh(\fracaq) |s(a¢,q¢)-s(a,q)|A_{h}(Q)=\frac{1}{\sum_{\frac{a}{q} \in {\cal F}_{Q}}h\left(\frac{a}{q}\right)} \times \sum_{\frac{a}{q} \in {\cal F}_{\!Q}}h\left(\frac{a}{q}\right) \vert s(a^{\prime},q^{\prime})-s(a,q)\vert
, where
h:[0,1] ? \Bbb Ch:[0,1] \rightarrow {\Bbb C}
is a continuous function with
ò01 h(t) d t 1 0\int_0^1 h(t) \, {\rm d} t \ne 0
,
\fracaq{\frac{a}{q}}
runs over
FQ{\cal F}_{\!Q}
, the set of Farey fractions of order Q in the unit interval [0,1] and
\fracaq < \fraca¢q¢{\frac{a}{q}}<\frac{a^{\prime}}{q^{\prime}}
are consecutive elements of
FQ{\cal F}_{\!Q}
. We show that the limit lim
Q→∞
A
h
(Q) exists and is independent of h. 相似文献
622.
Marian Vâ jâ itu Alexandru Zaharescu 《Proceedings of the American Mathematical Society》2002,130(12):3447-3452
Let be a real number, a positive integer and a subset of . We give an upper bound for the number of distinct lengths of gaps between the fractional parts .
623.
624.
625.
Alexandru Aleman Stefan Richter Carl Sundberg 《Transactions of the American Mathematical Society》2007,359(7):3369-3407
Let be a Hilbert space of analytic functions on the open unit disc such that the operator of multiplication with the identity function defines a contraction operator. In terms of the reproducing kernel for we will characterize the largest set such that for each , the meromorphic function has nontangential limits a.e. on . We will see that the question of whether or not has linear Lebesgue measure 0 is related to questions concerning the invariant subspace structure of .
We further associate with a second set , which is defined in terms of the norm on . For example, has the property that for all if and only if has linear Lebesgue measure 0.
It turns out that a.e., by which we mean that has linear Lebesgue measure 0. We will study conditions that imply that a.e.. As one corollary to our results we will show that if dim and if there is a such that for all and all we have , then a.e. and the following four conditions are equivalent:
(1) for some ,
(2) for all , ,
(3) has nonzero Lebesgue measure,
(4) every nonzero invariant subspace of has index 1, i.e., satisfies dim .
626.
The Hutchinson measure is the invariant measure associated with an iterated function system with probabilities. Generalized
iterated function systems (GIFS) are generalizations of iterated function systems which are obtained by considering contractions
from X × X to X, rather than contractions from a metric space X to itself. Along the lines of this generalization we consider GIFS with probabilities. In this paper we prove the existence
of an analogue of Hutchinson measure associated with a GIFS with probabilities and present some of its properties.
The work was supported by CNCSIS grant 8A;1067/2006. 相似文献
627.
628.
629.
Florin P. Boca Alexandru Zaharescu 《Transactions of the American Mathematical Society》2006,358(4):1797-1825
Let denote the repartition of the -level correlation measure of the finite set of directions , where is the fixed point and is an integer lattice point in the square . We show that the average of the pair correlation repartition over in a fixed disc converges as . More precisely we prove, for every and , the estimate
We also prove that for each individual point , the -level correlation diverges at any point as , and we give an explicit lower bound for the rate of divergence.
We also prove that for each individual point , the -level correlation diverges at any point as , and we give an explicit lower bound for the rate of divergence.
630.
Nicolae Popescu Marian Vâjâitu Alexandru Zaharescu 《Algebras and Representation Theory》2006,9(1):47-66
Let T be a transcendental element of
and
the orbit of T. On
we have a Haar measure
. The goal of this paper is to characterize all the elements of
for which the integral
, called the trace of T, is well defined.Presented by A. Verschoren 相似文献