全文获取类型
收费全文 | 3124篇 |
免费 | 142篇 |
国内免费 | 267篇 |
专业分类
化学 | 53篇 |
力学 | 122篇 |
综合类 | 33篇 |
数学 | 3020篇 |
物理学 | 305篇 |
出版年
2024年 | 3篇 |
2023年 | 40篇 |
2022年 | 36篇 |
2021年 | 44篇 |
2020年 | 91篇 |
2019年 | 79篇 |
2018年 | 77篇 |
2017年 | 78篇 |
2016年 | 96篇 |
2015年 | 62篇 |
2014年 | 129篇 |
2013年 | 289篇 |
2012年 | 79篇 |
2011年 | 183篇 |
2010年 | 144篇 |
2009年 | 208篇 |
2008年 | 221篇 |
2007年 | 206篇 |
2006年 | 180篇 |
2005年 | 170篇 |
2004年 | 116篇 |
2003年 | 149篇 |
2002年 | 120篇 |
2001年 | 109篇 |
2000年 | 107篇 |
1999年 | 97篇 |
1998年 | 83篇 |
1997年 | 86篇 |
1996年 | 64篇 |
1995年 | 28篇 |
1994年 | 25篇 |
1993年 | 15篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 16篇 |
1988年 | 7篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1936年 | 2篇 |
排序方式: 共有3533条查询结果,搜索用时 15 毫秒
61.
62.
63.
Under investigation in this paper is a generalized (3+1)-dimensional variable-coefficient B-type Kadomtsev–Petviashvili equation, which describes the propagation of nonlinear waves in fluid dynamics. Bilinear form and Bäcklund transformation are derived by virtue of the Bell polynomials. Besides, the one- and two-soliton solutions are constructed via the Hirota method. 相似文献
64.
Takuya Yamano 《Entropy (Basel, Switzerland)》2021,23(3)
An electron in a constant magnetic field has energy levels, known as the Landau levels. One can obtain the corresponding radial wavefunction of free-electron Landau states in cylindrical polar coordinates. However, this system has not been explored so far in terms of an information-theoretical viewpoint. Here, we focus on Fisher information associated with these Landau states specified by the two quantum numbers. Fisher information provides a useful measure of the electronic structure in quantum systems, such as hydrogen-like atoms and under some potentials. By numerically evaluating the generalized Laguerre polynomials in the radial densities, we report that Fisher information increases linearly with the principal quantum number that specifies energy levels, but decreases monotonically with the azimuthal quantum number m. We also present relative Fisher information of the Landau states against the reference density with , which is proportional to the principal quantum number. We compare it with the case when the lowest Landau level state is set as the reference. 相似文献
65.
In this paper, the a posteriori error estimates of Chebyshev–Petrov–Galerkin approximations are investigated. For simplicity, we choose the Poisson equation with Dirichlet boundary conditions to discuss the a posteriori error estimators, and deduce their efficient and reliable properties. Some numerical experiments are performed to verify the theoretical analysis for the a posteriori error estimators. 相似文献
66.
We prove a generalization of the Kibble–Slepian formula (for Hermite polynomials) and its unitary analogue involving the 2D Hermite polynomials recently proved in [16]. We derive integral representations for the 2D Hermite polynomials which are of independent interest. Several new generating functions for 2D q-Hermite polynomials will also be given. 相似文献
67.
In this paper, Bernstein operational matrix of fractional derivative of order α in the Caputo sense is derived. We also apply this matrix to the collocation method for solving multi-order fractional differential equations. The numerical results obtained by the present method compares favorably with those obtained by various collocation methods earlier in the literature. 相似文献
68.
William Slofstra 《Advances in Mathematics》2012,229(2):968-983
Braverman and Finkelberg have recently proposed a conjectural analogue of the geometric Satake isomorphism for untwisted affine Kac–Moody groups. As part of their model, they conjecture that (at dominant weights) Lusztig's q-analog of weight multiplicity is equal to the Poincare series of the principal nilpotent filtration of the weight space, as occurs in the finite-dimensional case. We show that the conjectured equality holds for all affine Kac–Moody algebras if the principal nilpotent filtration is replaced by the principal Heisenberg filtration. The main body of the proof is a Lie algebra cohomology vanishing result. We also give an example to show that the Poincare series of the principal nilpotent filtration is not always equal to the q-analog of weight multiplicity. Finally, we give some partial results for indefinite Kac–Moody algebras. 相似文献
69.
S. Ö. Akdemir S. D. Eryilmaz E. Öztekin 《International journal of quantum chemistry》2012,112(6):1585-1591
In this article, extremely simple analytical formulas are obtained for rotational overlap integrals which occur in integrals over two reduced rotation matrix elements. The analytical derivations are based on the properties of the Jacobi polynomials and beta functions. Numerical results and special values for rotational overlap integrals are obtained by using symmetry properties and recurrence relationships for reduced rotation matrix elements. The final results are of surprisingly simple structures and very useful for practical applications. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 相似文献
70.
Saad Zagloul Rida 《Applicable analysis》2013,92(1-2):93-102
We derive none some explicit formula for the power of fractional order (differential and integral) operators. 相似文献