全文获取类型
收费全文 | 6727篇 |
免费 | 38篇 |
国内免费 | 39篇 |
专业分类
化学 | 298篇 |
力学 | 122篇 |
综合类 | 1篇 |
数学 | 5784篇 |
物理学 | 599篇 |
出版年
2023年 | 19篇 |
2022年 | 8篇 |
2021年 | 23篇 |
2020年 | 31篇 |
2019年 | 57篇 |
2018年 | 34篇 |
2017年 | 41篇 |
2016年 | 37篇 |
2015年 | 29篇 |
2014年 | 68篇 |
2013年 | 290篇 |
2012年 | 196篇 |
2011年 | 75篇 |
2010年 | 61篇 |
2009年 | 756篇 |
2008年 | 650篇 |
2007年 | 478篇 |
2006年 | 191篇 |
2005年 | 176篇 |
2004年 | 161篇 |
2003年 | 218篇 |
2002年 | 432篇 |
2001年 | 509篇 |
2000年 | 480篇 |
1999年 | 569篇 |
1998年 | 452篇 |
1997年 | 280篇 |
1996年 | 107篇 |
1995年 | 107篇 |
1994年 | 107篇 |
1993年 | 19篇 |
1992年 | 17篇 |
1991年 | 9篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 13篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 4篇 |
1969年 | 2篇 |
排序方式: 共有6804条查询结果,搜索用时 156 毫秒
991.
We prove the existence of positive symmetric solutions to the semilinear elliptic problem
in both the radial case N = k ≥ 3 and the cylindrical case N ≥ k + 3 ≥ 6. The potential V is measurable, positive and it is only required to satisfy a mild integrability condition. The nonlinearity is continuous
and has a doublepower behavior, super-critical near the origin and sub-critical at infinity. If f is odd, we show that the radial problem has infinitely many solutions. In proving these results we exploit the compactness
of suitable restrictions of the embedding
Supported by MIUR, project “Variational Methods and Nonlinear Differential Equations”. 相似文献
992.
In this paper, we consider the following second-order three-point boundary value problem
where f : [0, 1] × R2 R is continuous, > 0, 0 < < 1 such that < 1. We give conditions on f and two pairs of lower and upper solutions to ensure the existence of at least three solutions of the given problem. Our method is based upon Leray-Schauder degree theory. The emphasis here is that f depends on the first derivative. Our results extend some results in the references.Received: 17 June 2004 相似文献
993.
Violeta Petkova 《Archiv der Mathematik》2005,84(4):311-324
Let
be a weighted space with weight . In this paper we show that for every Wiener-Hopf operator T on
and for every a I, there exists a function
such that
for all
Here (g)a denotes the function x g(x)eax for
and
where R+ is the spectral radius of the shift S : f(x) f(x–1) on
while
is the spectral radius of the backward shift S–1 : f(x) (P+f)(x+1) on
Moreover, there exists a constant C, depending on , such that
for every a I. If R– < R+, we prove that there exists a bounded holomorphic function v on
such that for
the function va is the restriction of v on the line
Received: 18 May 2004 相似文献
994.
We investigate spectral properties of integral operators of the form
acting on Banach spaces of analytic functions on the unit disc. In the case that g is a rational function, analytic on the unit disc, we obtain the spectrum, essential spectrum and index of Sg. Finally, we give examples of such operators pertaining to hyponormality.
Received: 30 August 2004; revised: 25 January 2005 相似文献
995.
Let X be a Banach space and let (ξj)j ≧ 1 be an i.i.d. sequence of symmetric random variables with finite moments of all orders. We prove that the following assertions
are equivalent:
Received: 10 January 2005; revised: 5 April 2005 相似文献
1. |
There exists a constant K such that
|
|
2. | X is isomorphic to a Hilbert space. |
996.
John W. Snow 《Algebra Universalis》2005,54(1):65-71
A congruence lattice L of an algebra A is called power-hereditary if every 0-1 sublattice of Ln is the congruence lattice of an algebra on An for all positive integers n. Let A and B be finite algebras. We prove
Received November 11, 2004; accepted in final form November 23, 2004. 相似文献
• | If ConA is distributive, then every subdirect product of ConA and ConB is a congruence lattice on A × B. |
• | If ConA is distributive and ConB is power-hereditary, then (ConA) × (ConB) is powerhereditary. |
• | If ConA ≅ N5 and ConB is modular, then every subdirect product of ConA and ConB is a congruence lattice. |
• | Every congruence lattice representation of N5 is power-hereditary. |
997.
Igor Wigman 《Monatshefte für Mathematik》2005,144(1):71-84
We solve an asymptotic problem in the geometry of numbers, where we count the number of singular n×n matrices where row vectors are primitive and of length at most T. Without the constraint of primitivity, the problem was solved by Y. Katznelson. We show that as T, the number is asymptotic to
for n3. The 3-dimensional case is the most problematic and we need to invoke an equidistribution theorem due to W. M. Schmidt. 相似文献
998.
Takao Komatsu 《Monatshefte für Mathematik》2005,145(1):47-60
The continued fractions studied by Tasoev are not widely known although their characteristics are very similar to those of Hurwitz continued fractions. Recently, the author found several general forms of Tasoev continued fractions, and by applying this method he also obtained some more general forms of Hurwitz continued fractions belonging to so called tanh-type and tan-type. In this paper, we constitute a new class of general forms of Hurwitz continued fractions of e-type. The known continued fraction expansions of e1/a (a 1), ae1/a and (1/a)e1/a are included as special cases. The corresponding Tasoev continued fractions are also derived. 相似文献
999.
Florian Luca 《Monatshefte für Mathematik》2005,146(3):239-256
In [2], it was shown that if a and b are multiplicatively independent integers and ɛ > 0, then the inequality gcd (an − 1,bn − 1) < exp(ɛn) holds for all but finitely many positive integers n. Here, we generalize the above result. In particular, we show that if f(x),f1(x),g(x),g1(x) are non-zero polynomials with integer coefficients, then for every ɛ > 0, the inequality
holds for all but finitely many positive integers n. 相似文献
1000.
In this paper we consider special elements of the Fock space #x2131;
n
. That is the space of entire functionsf:ℂ:
n
→ℂ, such that the followingL
2- condition is satisfied:
. Here we show that there exists an entire functiong:ℂ
n
→ℂ such that for every one-dimensional subspace Π⊂ℂ
n
and for all 0<∈<2 we have
, but in the limit case ∈=0 we have
. This result is analogue to a result from [1]. There holomorphic functions on the unit-ball are investigated. Furthermore
the proof — as the one in [1] — uses a theorem from [2]. Therefore we give another application of the results from [2] — namely
for spaces of entire functions. 相似文献