全文获取类型
收费全文 | 1610篇 |
免费 | 102篇 |
国内免费 | 73篇 |
专业分类
化学 | 599篇 |
晶体学 | 1篇 |
力学 | 129篇 |
综合类 | 11篇 |
数学 | 683篇 |
物理学 | 362篇 |
出版年
2023年 | 10篇 |
2022年 | 15篇 |
2021年 | 20篇 |
2020年 | 32篇 |
2019年 | 42篇 |
2018年 | 36篇 |
2017年 | 46篇 |
2016年 | 55篇 |
2015年 | 46篇 |
2014年 | 58篇 |
2013年 | 134篇 |
2012年 | 69篇 |
2011年 | 81篇 |
2010年 | 76篇 |
2009年 | 100篇 |
2008年 | 116篇 |
2007年 | 106篇 |
2006年 | 80篇 |
2005年 | 72篇 |
2004年 | 72篇 |
2003年 | 79篇 |
2002年 | 77篇 |
2001年 | 50篇 |
2000年 | 26篇 |
1999年 | 36篇 |
1998年 | 31篇 |
1997年 | 26篇 |
1996年 | 19篇 |
1995年 | 21篇 |
1994年 | 15篇 |
1993年 | 17篇 |
1992年 | 13篇 |
1991年 | 14篇 |
1990年 | 6篇 |
1989年 | 15篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 12篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有1785条查询结果,搜索用时 31 毫秒
81.
Khalfa Douak 《Journal of Computational and Applied Mathematics》1996,70(2):279-295
We are dealing with the concept of d-dimensional orthogonal (abbreviated d-orthogonal) polynomials, that is to say polynomials verifying one standard recurrence relation of order d + 1. Among the d-orthogonal polynomials one singles out the natural generalizations of certain classical orthogonal polynomials. In particular, we are concerned, in the present paper, with the solution of the following problem (P): Find all polynomial sequences which are at the same time Appell polynomials and d-orthogonal. The resulting polynomials are a natural extension of the Hermite polynomials.
A sequence of these polynomials is obtained. All the elements of its (d + 1)-order recurrence are explicitly determined. A generating function, a (d + 1)-order differential equation satisfied by each polynomial and a characterization of this sequence through a vectorial functional equation are also given. Among such polynomials one singles out the d-symmetrical ones (Definition 1.7) which are the d-orthogonal polynomials analogous to the Hermite classical ones. When d = 1 (ordinary orthogonality), we meet again the classical orthogonal polynomials of Hermite. 相似文献
82.
Yang Qingsheng 《Acta Mechanica Solida Sinica》1996,9(4):357-363
The smart composite materials reinforced by SMA show a high performance and special deformation behavior. The thermomechanical constitutive formulas of the composites are derived by means of Eshelby's equivalent inclusion method and Mori-Tanaka's mean field concept. The interaction between the inclusion and crack and toughening mechanism are considered and the energy release rate of a crack in the smart composite is calculated. This work shows that there are the multiple mechanisms contributing to the toughening of the smart composite materials reinforced by SMA.This project is supported by the National Natural Science Foundation of China. 相似文献
83.
We show that the restricted star-triangle relation introduced by Bazhanov and Baxter can be obtained either from the star-triangle relation of the chiral Potts model or from the star-square relation proposed by Kashaev, Mangazeev, and Stroganov, and give a response to a guess of Bazhanov and Baxter. 相似文献
84.
In this paper we study the 3-state Potts model on the triangular lattice which has two- and three-site interactions. Using a Peierls argument we obtain a rigorous bound on the transition temperature, thereby disproving a conjecture on the location of its critical point. Low-temperature series are generated and analyzed for three particular choices of the coupling constants; a phase diagram is then drawn on the basis of these considerations. Our analysis indicates that the antiferromagnetic transition and the transition along the coexistence line are of first order, implying the existence of a multicritical point in the ferromagnetic region. Relation of the triangularq-state Potts model with other lattice-statistical problems is also discussed. In particular, an Ashkin-Teller model and the hard-hexagon lattice gas solved by Baxter emerge as special cases in appropriate limits.Supported in part by NSF grant No. DMR 78-18808. 相似文献
85.
The functions of the main indices of refraction n(ν) and absorption κ(ν) of uniaxial thin polyethylene terephthalate films
have been calculated by the experimental spectra of frustrated total reflection of s-and p-polarized radiation in the 700–760-cm−1 range. The κo(ν) maximum falls at the the 727-cm−1 frequency and the maximum of κe(ν) falls at the the 724-and 732-cm− 1 frequencies.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 756–759, November–December, 2005. 相似文献
86.
Michael Růžička 《Applications of Mathematics》2004,49(6):565-609
Many electrorheological fluids are suspensions consisting of solid particles and a carrier oil. If such a suspension is exposed to a strong electric field the effective viscosity increases dramatically. In this paper we first derive a model which captures this behaviour. For the resulting system of equations we then prove local in time existence of strong solutions for large data. For these solutions we finally derive error estimates for a fully implicit time-discretization. 相似文献
87.
M. I. Shirokov 《International Journal of Theoretical Physics》2003,42(4):705-710
In order to obtain sum rules and spectral representations the Hermiticity property , A = A, of observables is used. It is shown that for certain and the property turns out to be inconsistent with the commutation relations that contain A. The known Schwinger paradox is explained by this inconsistency. 相似文献
88.
Let (Xn,dn) be a sequence of finite metric spaces of uniformlybounded diameter. An equivalence relation D on the product defined by if and only if is a c0-equality.A systematic study is made of c0-equalities and Borel reductionsbetween them. Necessary and sufficient conditions, expressedin terms of combinatorial properties of metrics dn, are obtainedfor a c0-equality to be effectively reducible to the isomorphismrelation of countable structures. It is proved that every Borelequivalence relation E reducible to a c0-equality D either reducesa c0-equality D' additively reducible to D, or is Borel-reducibleto the equality relation on countable sets of reals. An appropriatelydefined sequence of metrics provides a c0-equality which isa turbulent orbit equivalence relation with no minimum turbulentequivalence relation reducible to it. This answers a questionof Hjorth. It is also shown that, whenever E is an F-equivalencerelation and D is a c0-equality, every Borel equivalence relationreducible to both D and to E has to be essentially countable.2000 Mathematics Subject Classification: 03E15. 相似文献
89.
Nous montrons que pour toute sous-variété algébrique d'un tore multiplicatif (non contenue dans un sous-groupe algébrique propre), on peut choisir un ensemble Zariski dense de points algébriques de hauteur contrôlée, dont toutes les coordonnées sont multiplicativement indépendantes. Cet énoncé précise et généralise un théorème de S. Zhang qui lie la hauteur projective d'une varété au minimum essentiel de la hauteur des points algébriques de celle-ci. En tenant compte d'un résultat précédent des auteurs sur le problème de Lehmer généralisé à un tore, nous en déduisons une minoration pour la hauteur normalisée d'une sous-variété d'un tore. Cette dernière est optimale à un «-prés» en le degré géométrique de la variété étudiée (confer une conjecture du second auteur avec P. Philippon).In this article, we prove that on any subvariety of a multiplicative torus which is not contained in a proper algebraic subgroup, one can find a Zariski dense set of algebraic points of small height whose coordinates are multiplicatively independent. This statement generalizes an earlier result of S. Zhang which links the projective height of a variety with the essential minimum of its algebraic points. Taking into account an earlier result of the authors on the Lehmer problem generalized to a multiplicative torus, one deduces a lower bound for the normalized height of subvarieties of multiplicative groups. This lower bound is optimal up to an in the geometric degree of the variety studied (confer a conjecture by the second author and P. Philippon). 相似文献
90.
Stanisław Lewanowicz Eduardo Godoy Iván Area André Ronveaux Alejandro Zarzo 《Numerical Algorithms》2000,23(1):31-50
We propose an algorithm to construct recurrence relations for the coefficients of the Fourier series expansions with respect
to the q-classical orthogonal polynomials pk(x;q). Examples dealing with inversion problems, connection between any two sequences of q-classical polynomials, linearization
of ϑm(x) pn(x;q), where ϑm(x) is xmor (x;q)m, and the expansion of the Hahn-Exton q-Bessel function in the little q-Jacobi polynomials are discussed in detail.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献