全文获取类型
收费全文 | 77898篇 |
免费 | 329篇 |
国内免费 | 375篇 |
专业分类
化学 | 24105篇 |
晶体学 | 790篇 |
力学 | 6727篇 |
数学 | 31953篇 |
物理学 | 15027篇 |
出版年
2018年 | 10432篇 |
2017年 | 10258篇 |
2016年 | 6052篇 |
2015年 | 839篇 |
2014年 | 287篇 |
2013年 | 308篇 |
2012年 | 3760篇 |
2011年 | 10478篇 |
2010年 | 5622篇 |
2009年 | 6028篇 |
2008年 | 6587篇 |
2007年 | 8752篇 |
2006年 | 205篇 |
2005年 | 1294篇 |
2004年 | 1521篇 |
2003年 | 1970篇 |
2002年 | 1001篇 |
2001年 | 240篇 |
2000年 | 290篇 |
1999年 | 154篇 |
1998年 | 194篇 |
1997年 | 147篇 |
1996年 | 194篇 |
1995年 | 116篇 |
1994年 | 80篇 |
1993年 | 95篇 |
1992年 | 58篇 |
1991年 | 68篇 |
1990年 | 53篇 |
1989年 | 60篇 |
1988年 | 59篇 |
1987年 | 60篇 |
1986年 | 61篇 |
1985年 | 56篇 |
1984年 | 50篇 |
1983年 | 36篇 |
1982年 | 45篇 |
1981年 | 45篇 |
1980年 | 46篇 |
1979年 | 46篇 |
1978年 | 37篇 |
1973年 | 26篇 |
1914年 | 45篇 |
1913年 | 40篇 |
1912年 | 40篇 |
1910年 | 24篇 |
1909年 | 41篇 |
1908年 | 40篇 |
1907年 | 32篇 |
1904年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Annalisa Baldi Bruno Franchi 《Calculus of Variations and Partial Differential Equations》2003,16(3):283-298
Abstract. In this paper we study the notion of perimeter associated with doubling metric measures or strongly weights. We prove that the metric perimeter in the sense of L. Ambrosio and M. Miranda jr. coincides with the metric Minkowski
content and can be obtained also as a -limit of Modica-Mortola type degenerate integral functionals.
Received: 27 August 2001 / Accepted: 29 November 2001 / Published online: 10 June 2002
Investigation supported by University of Bologna, funds for selected research topics and by GNAMPA of INdAM, Italy. The authors
are very grateful to Luigi Ambrosio and Francesco Serra Cassano for making their preprints available to them, for listening
with patience and for many unvaluable suggestions. 相似文献
102.
The existence of infinitely many solutions of the following Dirichlet problem for p-mean curvature operator:
is considered, where Θ is a bounded domain in R
n
(n>p>1) with smooth boundary ∂Θ. Under some natural conditions together with some conditions weaker than (AR) condition, we prove that the above problem
has infinitely many solutions by a symmetric version of the Mountain Pass Theorem if
.
Supported by the National Natural Science Foundation of China (10171032) and the Guangdong Provincial Natural Science Foundation
(011606). 相似文献
103.
The set of all group relaxations of an integer program contains certain special members called Gomory relaxations. A family
of integer programs with a fixed coefficient matrix and cost vector but varying right hand sides is a Gomory family if every
program in the family can be solved by one of its Gomory relaxations. In this paper, we characterize Gomory families. Every
TDI system gives a Gomory family, and we construct Gomory families from matrices whose columns form a Hilbert basis for the
cone they generate. The existence of Gomory families is related to the Hilbert covering problems that arose from the conjectures
of Seb?. Connections to commutative algebra are outlined at the end.
Received: May 17, 2001 / Accepted: February 7, 2002
Published online: April 24, 2003
RID="⋆"
ID="⋆" Research partially supported by NSF grant DMS-0100141. 相似文献
104.
In this paper, we investigate the exact distribution of the waiting time for ther-th ℓ-overlapping occurrence of success-runs of a specified length in a sequence of two state Markov dependent trials. The
probability generating functions are derived explicitly, and as asymptotic results, relationships of a negative binomial distribution
of orderk and an extended Poisson distribution of orderk are discussed. We provide further insights into the run-related problems from the viewpoint of the ℓ-overlapping enumeration
scheme. We also study the exact distribution of the number of ℓ-overlapping occurrences of success-runs in a fixed number
of trials and derive the probability generating functions. The present work extends several properties of distributions of
orderk and leads us a new type of geneses of the discrete distributions. 相似文献
105.
Asger Hobolth Jan Pedersen Eva B. Vedel Jensen 《Annals of the Institute of Statistical Mathematics》2003,55(2):227-242
In this paper we propose a flexible continuous parametric shape model for star-shaped planar objects. The model is based on
a polar Fourier expansion of the normalized radius-vector function. The expected phase amplitudes are modelled by a simple
regression with parameters having nice geometric interpretations. The suggestedgeneralized p-order model is an extension of first- and second-order Gaussian shape models, and in particular the Gaussian assumption is relaxed. The
statistical analysis is straightforward, as demonstrated by an application concerning shape discrimination of two cell nuclei
populations. 相似文献
106.
107.
108.
Some improvements and generalizations of Finks results about Hadamards inequality for log-concave functions are given.AMS Subject Classification: 26D07, 26D15, 26A51. 相似文献
109.
Xu Cheng 《Mathematische Annalen》2003,325(2):229-248
Let M be a 2m-dimensional compact Riemannian manifold with Anosov geodesic flow. We prove that every closed bounded k form, k≥2, on the universal covering of M is d(bounded). Further, if M is homotopy equivalent to a compact K?hler manifold, then its Euler number χ(M) satisfies (−1)
m
χ(M)>0.
Received: 25 September 2001 / Published Online: 16 October 2002 相似文献
110.
We study the metrical theory of fibred systems, in particular, in the case of continued fraction mixing systems. We get the
limit distribution of the largest value of a continued fraction mixing stationary stochastic process with infinite expectation
and some related results. These are analogous to J. Galambos, W. Philipp, and H. G. Diamond–J. D. Vaaler theorems for the
regular continued fractions. As an application, we see that these theorems hold for Jacobi-Perron algorithm.
Received September 30, 2001; in revised form January 8, 2002 相似文献