全文获取类型
收费全文 | 10807篇 |
免费 | 363篇 |
国内免费 | 507篇 |
专业分类
化学 | 3123篇 |
晶体学 | 251篇 |
力学 | 115篇 |
综合类 | 63篇 |
数学 | 6301篇 |
物理学 | 1824篇 |
出版年
2023年 | 66篇 |
2022年 | 102篇 |
2021年 | 113篇 |
2020年 | 116篇 |
2019年 | 258篇 |
2018年 | 240篇 |
2017年 | 178篇 |
2016年 | 175篇 |
2015年 | 164篇 |
2014年 | 306篇 |
2013年 | 681篇 |
2012年 | 337篇 |
2011年 | 651篇 |
2010年 | 613篇 |
2009年 | 764篇 |
2008年 | 760篇 |
2007年 | 780篇 |
2006年 | 608篇 |
2005年 | 475篇 |
2004年 | 426篇 |
2003年 | 351篇 |
2002年 | 458篇 |
2001年 | 229篇 |
2000年 | 216篇 |
1999年 | 217篇 |
1998年 | 197篇 |
1997年 | 133篇 |
1996年 | 254篇 |
1995年 | 215篇 |
1994年 | 207篇 |
1993年 | 162篇 |
1992年 | 166篇 |
1991年 | 125篇 |
1990年 | 100篇 |
1989年 | 77篇 |
1988年 | 36篇 |
1987年 | 36篇 |
1986年 | 33篇 |
1985年 | 71篇 |
1984年 | 57篇 |
1983年 | 38篇 |
1982年 | 55篇 |
1981年 | 74篇 |
1980年 | 56篇 |
1979年 | 30篇 |
1978年 | 48篇 |
1977年 | 50篇 |
1976年 | 48篇 |
1975年 | 23篇 |
1974年 | 32篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Brian Hartwig 《Linear algebra and its applications》2007,422(1):219-235
Recently Terwilliger and the present author found a presentation for the three-point sl2 loop algebra via generators and relations. To obtain this presentation we defined a Lie algebra ? by generators and relations and displayed an isomorphism from ? to the three-point sl2 loop algebra. In this paper we classify the finite-dimensional irreducible ?-modules. 相似文献
72.
Pavel Shumyatsky 《Monatshefte für Mathematik》2007,152(2):169-175
The following theorem is proved. Let n be a positive integer and q a power of a prime p. There exists a number m = m(n, q) depending only on n and q such that if G is any residually finite group satisfying the identity ([x
1,n
y
1] ⋯ [x
m,n
y
m
])q ≡ 1, then the verbal subgroup of G corresponding to the nth Engel word is locally finite. 相似文献
73.
Fractal Gaussian models have been widely used to represent the singular behavior of phenomena arising in different applied fields; for example, fractional Brownian motion and fractional Gaussian noise are considered as monofractal models in subsurface hydrology and geophysical studies Mandelbrot [The Fractal Geometry of Nature, Freeman Press, San Francisco, 1982 [13]]. In this paper, we address the problem of least-squares linear estimation of an intrinsic fractal input random field from the observation of an output random field affected by fractal noise (see Angulo et al. [Estimation and filtering of fractional generalised random fields, J. Austral. Math. Soc. A 69 (2000) 1-26 [2]], Ruiz-Medina et al. [Fractional generalized random fields on bounded domains, Stochastic Anal. Appl. 21 (2003a) 465-492], Ruiz-Medina et al. [Fractional-order regularization and wavelet approximation to the inverse estimation problem for random fields, J. Multivariate Anal. 85 (2003b) 192-216]. Conditions on the fractality order of the additive noise are studied to obtain a bounded inversion of the associated Wiener-Hopf equation. A stable solution is then obtained in terms of orthogonal bases of the reproducing kernel Hilbert spaces associated with the random fields involved. Such bases are constructed from orthonormal wavelet bases (see Angulo and Ruiz-Medina [Multiresolution approximation to the stochastic inverse problem, Adv. in Appl. Probab. 31 (1999) 1039-1057], Angulo et al. [Wavelet-based orthogonal expansions of fractional generalized random fields on bounded domains, Theoret. Probab. Math. Stat. (2004), in press]). A simulation study is carried out to illustrate the influence of the fractality orders of the output random field and the fractal additive noise on the stability of the solution derived. 相似文献
74.
Long-period fibre gratings inside standard single-mode optical communication fibres are successfully fabricated with infrared femtosecond laser pulses. The refractive index perturbations are well confined within the fibre core by choosing the proper laser focusing parameters and translation speed of the fibre during the direct laser writing process. With the self-focusing effect considered and at a constant average irradiation dose of 1.62 × 10^3 J/(cm^2μm), the threshold intensity for fabricating long-period gratings with infrared femtosecond laser pulses is determined to be 5.13 × 10^13 W/cm2. 相似文献
75.
Stephen J. Gardiner 《Advances in Mathematics》2007,214(1):417-436
This paper answers a question of Fuglede about minimal positive harmonic functions associated with irregular boundary points. As a consequence, an old and central problem of fine potential theory, concerning the Riesz decomposition, is resolved. Namely, it is shown that, on certain fine domains, there exist positive finely superharmonic functions which do not admit any positive finely harmonic minorant and yet are not fine potentials. 相似文献
76.
77.
Wen-Rong Dai 《Journal of Differential Equations》2007,235(1):127-165
In this paper, we study the global existence and the asymptotic behavior of classical solution of the Cauchy problem for quasilinear hyperbolic system with constant multiple and linearly degenerate characteristic fields. We prove that the global C1 solution exists uniquely if the BV norm of the initial data is sufficiently small. Based on the existence result on the global classical solution, we show that, when the time t tends to the infinity, the solution approaches a combination of C1 traveling wave solutions. Finally, we give an application to the equation for time-like extremal surfaces in the Minkowski space-time R1+n. 相似文献
78.
79.
We give general conditions on a generator of a C0-semigroup (resp. of a C0-resolvent) on Lp(E,μ), p ≥ 1, where E is an arbitrary (Lusin) topological space and μ a σ-finite measure on its Borel σ-algebra, so that it generates a sufficiently
regular Markov process on E. We present a general method how these conditions can be checked in many situations. Applications to solve stochastic differential
equations on Hilbert space in the sense of a martingale problem are given.
Dedicated to Giuseppe Da Prato on the occasion of his 70th birthday 相似文献
80.
Piotr Niemiec 《Topology and its Applications》2006,153(18):3373-3382
Equicontinuous semigroups of transformations of a compact Hausdorff space and their sets of all invariant (Borel, regular and probabilistic) measures are studied. Conditions equivalent to the existence of at least one invariant measure are given. The (algebraic and topological) structure of the set of invariant measures is researched. 相似文献