全文获取类型
收费全文 | 7486篇 |
免费 | 729篇 |
国内免费 | 506篇 |
专业分类
化学 | 1271篇 |
晶体学 | 15篇 |
力学 | 950篇 |
综合类 | 127篇 |
数学 | 3129篇 |
物理学 | 3229篇 |
出版年
2024年 | 9篇 |
2023年 | 54篇 |
2022年 | 110篇 |
2021年 | 119篇 |
2020年 | 182篇 |
2019年 | 185篇 |
2018年 | 186篇 |
2017年 | 258篇 |
2016年 | 287篇 |
2015年 | 214篇 |
2014年 | 432篇 |
2013年 | 522篇 |
2012年 | 352篇 |
2011年 | 458篇 |
2010年 | 344篇 |
2009年 | 527篇 |
2008年 | 587篇 |
2007年 | 564篇 |
2006年 | 473篇 |
2005年 | 393篇 |
2004年 | 372篇 |
2003年 | 281篇 |
2002年 | 264篇 |
2001年 | 217篇 |
2000年 | 213篇 |
1999年 | 177篇 |
1998年 | 167篇 |
1997年 | 144篇 |
1996年 | 113篇 |
1995年 | 93篇 |
1994年 | 68篇 |
1993年 | 50篇 |
1992年 | 47篇 |
1991年 | 32篇 |
1990年 | 25篇 |
1989年 | 29篇 |
1988年 | 42篇 |
1987年 | 25篇 |
1986年 | 13篇 |
1985年 | 11篇 |
1984年 | 13篇 |
1983年 | 4篇 |
1982年 | 14篇 |
1981年 | 11篇 |
1980年 | 5篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1973年 | 5篇 |
1957年 | 3篇 |
排序方式: 共有8721条查询结果,搜索用时 0 毫秒
101.
Since the Jost solutions of the DNLS equation does not tend to the free Jost solutioins as |λ| →∞, the usual inverse scattering transform (IST) must be revised. Beside the Kaup and Newell's approach, we propose a simple revision in constructing the equations of IST, where the usual Zakharov-Shabat kern is revised by multiplying λ-2 or λ-1. To justify the revision we show that the Jost solutions obtained do satisfy the pair of compatibility equations. 相似文献
102.
103.
We solve the problem of describing compatible nonlocal Poisson brackets of hydrodynamic type. We prove that for nonsingular pairs of compatible nonlocal Poisson brackets of hydrodynamic type, there exist special local coordinates such that the metrics and the Weingarten operators of both brackets are diagonal. The nonlinear evolution equations describing all nonsingular pairs of compatible nonlocal Poisson brackets of hydrodynamic type are derived in these special coordinates, and the integrability of these equations is proved using the inverse scattering transform. The Lax pairs with a spectral parameter for these equations are found. We construct various classes of integrable reductions of the derived equations. These classes of reductions are of an independent differential-geometric and applied interest. In particular, if one of the compatible Poisson brackets is local, we obtain integrable reductions of the classical Lamé equations describing all orthogonal curvilinear coordinate systems in a flat space; if one of the compatible brackets is generated by a constant-curvature metric, the corresponding equations describe integrable reductions of the equations for orthogonal curvilinear coordinate systems in a space of constant curvature. 相似文献
104.
Alexander Koldobsky 《Advances in Applied Mathematics》2004,33(4):728-732
The Busemann–Petty problem asks whether origin-symmetric convex bodies in Rn with smaller areas of all central hyperplane sections necessarily have smaller n-dimensional volume. The solution was completed in the end of the 1990s, and the answer is affirmative if n4 and negative if n5. Since the answer is negative in most dimensions, it is natural to ask what information about the volumes of central sections of two bodies does allow to compare the n-dimensional volumes of these bodies in all dimensions. In this article we give an answer to this question in terms of certain powers of the Laplace operator applied to the section function of the body. 相似文献
105.
Milan Merkle 《Journal of Mathematical Analysis and Applications》2004,293(1):210-218
We say that f is reciprocally convex if x?f(x) is concave and x?f(1/x) is convex on (0,+∞). Reciprocally convex functions generate a sequence of quasi-arithmetic means, with the first one between harmonic and arithmetic mean and others above the arithmetic mean. We present several examples related to the gamma function and we show that if f is a Stieltjes transform, then −f is reciprocally convex. An application in probability is also presented. 相似文献
106.
Yong Chan Kim 《Journal of Mathematical Analysis and Applications》2004,299(2):433-447
In this paper, nonlinear integral operators on normalized analytic functions in the unit disk are investigated in connection with the pre-Schwarzian derivative and the Hornich operation. In particular, several nontrivial relations between these operators and the class of strongly starlike functions will be deduced. 相似文献
107.
Frictionless indentation responses of transversely isotropic piezoelectric film/rigid substrate systems under circular cylindrical indenter (i.e., punch), conical indenter (i.e., cone), and spherical indenter (i.e., sphere) are investigated. Both insulating and conducting indenters are considered. The technique of Hankel transformation is employed to derive the corresponding dual integral equations for the mixed boundary value indentation problems. For the two limiting cases of infinitely thick and infinitely thin piezoelectric films, closed-form solutions are obtained. For piezoelectric films of finite thickness, a numerical method is constructed to solve the dual integral equations and semi-empirical models having only two unknown parameters are proposed for the responses of indentation force, electric charge and electric potential, and contact radius. With the two parameters inferred from the numerical results, the semi-empirical formulae are found to provide good estimates of the indentation responses for the two limiting cases of infinitely thick and thin piezoelectric films, as well as those in between. The inferred parameters in the proposed semi-empirical formulae for normalized indentation force and electric charge are checked against four different piezoelectric materials and are found to be insensitive to the selection of piezoelectric materials. It is believed that the proposed semi-empirical indentation formulae are useful in developing experimental indentation techniques to extract the material properties of piezoelectric films. 相似文献
108.
JI An-Chun TIAN Guang-Shan 《理论物理通讯》2007,47(1):171-180
In the present paper, we investigate the quantum phase transition in a spatially anisotropic antiferrornagnetic Heisenberg model of S =1 with single-ion energy anisotropy. By using the Schwinger boson representation, we calculate the Gaussian correction to the critical value J⊥^c caused by quantum spin fluctuations. We find that, for the positive single-ion energy, a nonzero value of J⊥^c is always needed to stabilize the antiferromagnetic long-range order in this model. It resolves a difference among literature and shows clearly that the effect of quantum fluctuations may qualitatively change a result obtained by the mean-field theories on lower-dimensional systems. 相似文献
109.
Mathematical Notes - 相似文献
110.
We establish the similarity between certain Volterra integral operators and the Riemann--Liouville fractional integration operator as well as the existence of a triangular transformation operator for integro-differential equations of fractional order. The results obtained are consistent with similar results for the case of integer order. 相似文献