全文获取类型
收费全文 | 3076篇 |
免费 | 292篇 |
国内免费 | 366篇 |
专业分类
化学 | 54篇 |
力学 | 303篇 |
综合类 | 66篇 |
数学 | 2747篇 |
物理学 | 564篇 |
出版年
2024年 | 5篇 |
2023年 | 30篇 |
2022年 | 34篇 |
2021年 | 49篇 |
2020年 | 72篇 |
2019年 | 58篇 |
2018年 | 69篇 |
2017年 | 90篇 |
2016年 | 88篇 |
2015年 | 68篇 |
2014年 | 128篇 |
2013年 | 161篇 |
2012年 | 91篇 |
2011年 | 114篇 |
2010年 | 125篇 |
2009年 | 175篇 |
2008年 | 223篇 |
2007年 | 242篇 |
2006年 | 183篇 |
2005年 | 219篇 |
2004年 | 156篇 |
2003年 | 175篇 |
2002年 | 177篇 |
2001年 | 143篇 |
2000年 | 152篇 |
1999年 | 122篇 |
1998年 | 121篇 |
1997年 | 105篇 |
1996年 | 64篇 |
1995年 | 40篇 |
1994年 | 40篇 |
1993年 | 30篇 |
1992年 | 20篇 |
1991年 | 22篇 |
1990年 | 24篇 |
1989年 | 19篇 |
1988年 | 11篇 |
1987年 | 14篇 |
1986年 | 6篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1974年 | 4篇 |
1973年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有3734条查询结果,搜索用时 187 毫秒
61.
Horst-Heino v. Borzeszkowski Hans-Jürgen Treder 《General Relativity and Gravitation》2002,34(11):1909-1918
The affine theory was conceived as a geometric model, wherein the connection field is the primary structure of the space-time. According to the program lying on the basis of this theory, metric and some sort of matter are somehow to be deduced from the connection field. In the present paper, we point out classical ways to a realization of this program. It is shown that, even in that case where the introduction of the metric seems to exclude the coupling of gravity to matter, the situation is not so hopeless as one may assume. In particular, for a symmetric Einstein tensor, it is answered the old question as to a self-consistent introduction of a metric and a metrical energy-momentum tensor controversially debated by Einstein, Eddington, and Weyl. 相似文献
62.
Irina Markina 《Journal of Functional Analysis》2007,245(2):475-492
We consider coefficient bodies Mn for univalent functions. Based on the Löwner-Kufarev parametric representation we get a partially integrable Hamiltonian system in which the first integrals are Kirillov's operators for a representation of the Virasoro algebra. Then Mn are defined as sub-Riemannian manifolds. Given a Lie-Poisson bracket they form a grading of subspaces with the first subspace as a bracket-generating distribution of complex dimension two. With this sub-Riemannian structure we construct a new Hamiltonian system to calculate regular geodesics which turn to be horizontal. Lagrangian formulation is also given in the particular case M3. 相似文献
63.
Ali Ghaffari 《Proceedings Mathematical Sciences》2007,117(2):177-183
In this paper, among other things, we state and prove the mean ergodic theorem for amenable semigroup algebras. 相似文献
64.
E. A. Sbrodova 《Mathematical Notes》2007,82(3-4):531-534
In this paper, we present an algorithm which, for a given compact orientable irreducible boundary irreducible 3-manifold M, verifies whether M contains an essential orientable surface (possibly, with boundary), whose genus is at most N. The algorithm is based on Haken’s theory of normal surfaces, and on a trick suggested by Jaco and consisting in estimating the mean length of boundary curves in an unknown essential surface of a given genus in the given manifold. 相似文献
65.
Atsushi Kasue 《Potential Analysis》2006,24(2):137-194
We study spectral convergence of compact Riemannian manifolds or more generally certain Dirichlet spaces, obtaining some compactness
results on harmonic functions and harmonic maps.
Mathematics Subject Classifications (2000) 53C21, 58D17, 58J50.
Atsushi Kasue: Partly supported by the Grant-in-Aid for Scientific Research (B) No. 15340053 of the Japan Society for the
Promotion of Science. 相似文献
66.
V. N. Dubinin 《Mathematical Notes》2006,80(1-2):31-35
It is shown that if P(z) = z n + ? is a polynomial with connected lemniscate E(P) = {z: ¦P(z)¦ ≤ 1} and m critical points, then, for any n? m+1 points on the lemniscate E(P), there exists a continuum γ ? E(P) of logarithmic capacity cap γ ≤ 2?1/n which contains these points and all zeros and critical points of the polynomial. As corollaries, estimates for continua of minimum capacity containing given points are obtained. 相似文献
67.
Thomas G. Goodwillie 《K-Theory》1990,4(1):1-27
Let P be the (stable, smooth) pseudoisotopy space of the space X. For any map Y: YX of spaces, we identify the homotopy type of the fiber of P(f): P(f) P(f) in a stable range, roughly twice the connectivity of the map YX. We establish some language for discussing and manipulating such stable-range relative calculations for any homotopy functor. The theorem about P has a corollary about Waldhausen's A.
Dedicated to Alexander GrothendieckResearch supported in part by NSF grant DMS-8806444 and by a Sloan Fellowship. Research at MSRI supported in part by NSF grant DMS-8505550. 相似文献
68.
Let
l
be the critical exponent associated with the probability thatl independentN-step ordinary random walks, starting at nearby points, are mutually avoiding. Using Monte Carlo methods combined with a maximum-likelihood data analysis, we find that in two dimensions 2=0.6240±0.0005±0.0011 and 3=1.4575±0.0030±0.0052, where the first error bar represents systematic error due to corrections to scaling (subjective 95% confidence limits) and the second error bar represents statistical error (classical 95% confidence limits). These results are in good agreement with the conformal-invariance predictions 2=5/8 and 3=35/24. 相似文献
69.
A. Shapiro 《Journal of Optimization Theory and Applications》1990,66(3):477-487
Various definitions of directional derivatives in topological vector spaces are compared. Directional derivatives in the sense of Gâteaux, Fréchet, and Hadamard are singled out from the general framework of -directional differentiability. It is pointed out that, in the case of finite-dimensional spaces and locally Lipschitz mappings, all these concepts of directional differentiability are equivalent. The chain rule for directional derivatives of a composite mapping is discussed. 相似文献
70.
The on-line incorporation of cloud point extraction (CPE) to flow injection analysis (FIA) is modified to extract and preconcentrate metal species rapidly, avoiding the formation of hydrophobic complexes, using a mixed micellar medium. Coupling the procedure with chemiluminescence (CL) detection based on the catalytic activity of metal species on the luminol-hydrogen peroxide reaction and enhancing the signal with the presence of a micellar carrier containing bromide ions produces a powerful tool for the preconcentration and determination of metal species at ng l−1 levels. As an analytical demonstration ultratrace concentrations of chromium were conveniently detected and quantified in samples with a complex matrix such as seawater and wastewater. The figures of merit for the determination of chromium were: 0.9-1.6% R.S.D. (n=5) with detection and quantification limits 0.5 and 2.0 ng l−1, respectively. The calibration graph was rectilinear from 2 to 200 ng l−1 (r=0.9996, n=6). Several other metal ions were determined in ideal situations, with analogous results. 相似文献