全文获取类型
收费全文 | 8979篇 |
免费 | 810篇 |
国内免费 | 700篇 |
专业分类
化学 | 2695篇 |
晶体学 | 10篇 |
力学 | 794篇 |
综合类 | 154篇 |
数学 | 3562篇 |
物理学 | 3274篇 |
出版年
2024年 | 7篇 |
2023年 | 72篇 |
2022年 | 121篇 |
2021年 | 112篇 |
2020年 | 218篇 |
2019年 | 217篇 |
2018年 | 236篇 |
2017年 | 293篇 |
2016年 | 318篇 |
2015年 | 234篇 |
2014年 | 446篇 |
2013年 | 510篇 |
2012年 | 405篇 |
2011年 | 525篇 |
2010年 | 418篇 |
2009年 | 581篇 |
2008年 | 631篇 |
2007年 | 646篇 |
2006年 | 554篇 |
2005年 | 517篇 |
2004年 | 491篇 |
2003年 | 379篇 |
2002年 | 350篇 |
2001年 | 265篇 |
2000年 | 303篇 |
1999年 | 247篇 |
1998年 | 222篇 |
1997年 | 198篇 |
1996年 | 134篇 |
1995年 | 126篇 |
1994年 | 104篇 |
1993年 | 56篇 |
1992年 | 57篇 |
1991年 | 58篇 |
1990年 | 46篇 |
1989年 | 41篇 |
1988年 | 58篇 |
1987年 | 47篇 |
1986年 | 26篇 |
1985年 | 38篇 |
1984年 | 34篇 |
1983年 | 22篇 |
1982年 | 26篇 |
1981年 | 32篇 |
1980年 | 13篇 |
1979年 | 15篇 |
1978年 | 7篇 |
1977年 | 11篇 |
1976年 | 5篇 |
1975年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Consider two Toeplitz operators Tg, Tf on the Segal-Bargmann space over the complex plane. Let us assume that g is a radial function and both operators commute. Under certain growth condition at infinity of f and g we show that f must be radial, as well. We give a counterexample of this fact in case of bounded Toeplitz operators but a fast growing radial symbol g. In this case the vanishing commutator [Tg,Tf]=0 does not imply the radial dependence of f. Finally, we consider Toeplitz operators on the Segal-Bargmann space over Cn and n>1, where the commuting property of Toeplitz operators can be realized more easily. 相似文献
952.
If Ω is a smoothly bounded multiply-connected domain in the complex plane and S belongs to the Toeplitz algebra τ of the Bergman space of Ω, we show that S is compact if and only if its Berezin transform vanishes at the boundary of Ω. We also show that every element S in T, the C?-subalgebra of τ generated by Toeplitz operators with symbols in H∞(Ω), has a canonical decomposition for some R in the commutator ideal CT; and S is in CT iff the Berezin transform vanishes identically on the set M1 of trivial Gleason parts. 相似文献
953.
For sequences of the positively associated random variables which are strictly weaker than the classical associated random ones introduced by Esary et al. (1967) [7], strong convergence rate is obtained, which reaches the available one for independent random variables in terms of Berstein type inequality. Further, we give the corresponding precise asymptotics with respect to the rate mentioned above, which extend and improve the relevant results in Fu (2009) [8]. 相似文献
954.
María M. Martínez 《Journal of Mathematical Analysis and Applications》2011,375(1):196-206
Let X be a Banach space and let f∈L∞(R+;X) whose Laplace transform extends analytically to some region containing iR?{0}, possibly having a pole at the origin. In this paper, we give estimates of the decay of certain slight suitable modification of f in terms of the growth of its Laplace transform along the imaginary axis. This technique is applied to obtain decay estimates of smooth orbits of bounded C0-semigroups whose infinitesimal generators have an arbitrary finite boundary spectrum. These results are close to those given recently by C.J.K. Batty and T. Duyckaerts. 相似文献
955.
We consider a process given by the SDE , t∈[0,T), with initial condition , where T∈(0,∞], α∈R, (Bt)t∈[0,T) is a standard Wiener process, b:[0,T)→R?{0} and σ:[0,T)→(0,∞) are continuously differentiable functions. Assuming , t∈[0,T), with some K∈R, we derive an explicit formula for the joint Laplace transform of and for all t∈[0,T) and for all α∈R. Our motivation is that the maximum likelihood estimator (MLE) of α can be expressed in terms of these random variables. As an application, we show that in case of α=K, K≠0,
956.
A space of pseudoquotients is introduced that is shown to be isomorphic to the space of tempered distributions on RN. The Fourier transform is defined as a map from the space of pseudoquotients to the space of tempered distributions and as a transformation on pseudoquotients. 相似文献
957.
Mansoor Rezghi 《Linear algebra and its applications》2011,435(3):422-658
The concepts of tensors with diagonal and circulant structure are defined and a framework is developed for the analysis of such tensors. It is shown a tensor of arbitrary order, which is circulant with respect to two particular modes, can be diagonalized in those modes by discrete Fourier transforms. This property can be used in the efficient solution of linear systems involving contractive products of tensors with circulant structure. Tensors with circulant structure occur in models for image blurring with periodic boundary conditions. It is shown that the new framework can be applied to such problems. 相似文献
958.
959.
In this paper we introduce the continuous quaternion wavelet transform (CQWT). We express the admissibility condition in terms of the (right-sided) quaternion Fourier transform. We show that its fundamental properties, such as inner product, norm relation, and inversion formula, can be established whenever the quaternion wavelets satisfy a particular admissibility condition. We present several examples of the CQWT. As an application we derive a Heisenberg type uncertainty principle for these extended wavelets. 相似文献
960.
Asymptotic properties of fractional delay differential equations 总被引:1,自引:0,他引:1
Katja Krol 《Applied mathematics and computation》2011,218(5):1515-1532
In this paper we study the asymptotic properties of d-dimensional linear fractional differential equations with time delay. We present necessary and sufficient conditions for asymptotic stability of equations of this type using the inverse Laplace transform method and prove polynomial decay of stable solutions. Two examples illustrate the obtained analytical results. 相似文献