全文获取类型
收费全文 | 3893篇 |
免费 | 529篇 |
国内免费 | 493篇 |
专业分类
化学 | 916篇 |
晶体学 | 32篇 |
力学 | 547篇 |
综合类 | 125篇 |
数学 | 1802篇 |
物理学 | 1493篇 |
出版年
2024年 | 10篇 |
2023年 | 34篇 |
2022年 | 69篇 |
2021年 | 84篇 |
2020年 | 73篇 |
2019年 | 79篇 |
2018年 | 67篇 |
2017年 | 113篇 |
2016年 | 121篇 |
2015年 | 117篇 |
2014年 | 208篇 |
2013年 | 288篇 |
2012年 | 227篇 |
2011年 | 236篇 |
2010年 | 179篇 |
2009年 | 244篇 |
2008年 | 263篇 |
2007年 | 281篇 |
2006年 | 234篇 |
2005年 | 226篇 |
2004年 | 194篇 |
2003年 | 197篇 |
2002年 | 187篇 |
2001年 | 165篇 |
2000年 | 152篇 |
1999年 | 151篇 |
1998年 | 141篇 |
1997年 | 105篇 |
1996年 | 95篇 |
1995年 | 59篇 |
1994年 | 69篇 |
1993年 | 30篇 |
1992年 | 40篇 |
1991年 | 27篇 |
1990年 | 23篇 |
1989年 | 10篇 |
1988年 | 23篇 |
1987年 | 12篇 |
1986年 | 16篇 |
1985年 | 7篇 |
1984年 | 23篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有4915条查询结果,搜索用时 15 毫秒
11.
分形介质的传热与传质分析(综述) 总被引:9,自引:0,他引:9
本文论述了分形介质的分形理论和数学基础,并简要综述了用分形理论和方法研究分形介质的传热与传质特性(如多孔介质的渗透率、热导率以及池核态沸腾换热)方面目前所取得的研究进展,最后扼要展望了用分形理论和方法进一步研究分形介质的传热与传质的可能的若干课题和方向。 相似文献
12.
Trond Stølen Gustavsen 《Compositio Mathematica》2003,138(2):199-231
We relate the equisingular deformation theory of plane curve singularities and sandwiched surface singularities. We show the existence of a smooth map between the two corresponding deformation functors and study the kernel of this map. In particular we show that the map is an isomorphism when a certain invariant is large enough. 相似文献
13.
We present a practical polynomial-time algorithm for computing the
zeta function of a Kummer curve over a finite field of small
characteristic. Such algorithms have recently been obtained using a
method of Kedlaya based upon Monsky–Washnitzer cohomology, and are of
interest in cryptography. We take a different approach.
The problem is reduced to that of computing the L-function
of a multiplicative character sum. This latter task is achieved via a
cohomological formula based upon the work of Dwork and Reich. We show,
however, that our method and that of Kedlaya are very closely related.Dedicated to the memory of Gian-Carlo Rota 相似文献
14.
M. A. Efendiev J. Fuhrmann S. V. Zelik 《Mathematical Methods in the Applied Sciences》2004,27(8):907-930
For the Boussinesq approximation of the equations of coupled heat and fluid flow in a porous medium we show that the corresponding system of partial differential equations possesses a global attractor. We give lower and upper bounds of the Hausdorff dimension of the attractor depending on a physical parameter of the system, namely the Rayleigh number of the flow. Numerical experiments confirm the theoretical findings and raise new questions on the structure of the solutions of the system. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
15.
带有给定凸切线多边形的保形五次样条逼近 总被引:3,自引:0,他引:3
本讨论带有给定切线多边形的保形逼近问题.给出了一条与给定切线多边形相切的保形五次参数祥条曲线。 相似文献
16.
The paper discusses the relationship between weights and control vertices of two rational NURBS curves of degree two or three with all weights larger than zero when they represent the same curve parametrically and geometrically, and gives sufficient and necessary conditions for coincidence of two rational NURBS curves in non-degeneracy case. 相似文献
17.
HANXI'AN HUANGXILI 《高校应用数学学报(英文版)》1998,13(4):445-450
For two rational quadratic B-spline curves with same control vertexes, the cross ratio of four eollinear points are represented; which are any one of the vertexes, and the two points that the ray initialing from the vertex intersects with the corresponding segments of the twocurves, and the point the ray intersecting with the connecting line between the two neighboring vertexes. Different from rational quadratic Beeier curves, the value is generally related with the loeation of the ray, and the necessary and sufficient condition o5 the ratio being independent of the ray‘s loeation is showed. Alsn another cross ratio o5 the following four collinear points are suggested, i.e. one vertex, the points that the ray from the initlal vertex intersects respectivdy with the curve segmentt the line connecting the segments end points, and the line connecting the two neighboring vertexes. This cross ratio is concerned only whh the ray‘s location, butnot with the weights of the curve. Furthermore, the cross ratio is projective invariant under the projective transformation between the two segments. 相似文献
18.
Understanding of the basic nature of arc root fluctuation is still one of the unsolved problems in thermal arc plasma physics.
It has direct impact on myriads of thermal plasma applications being implemented at present. Recently, chaotic nature of arc
root behavior has been reported through the analysis of voltages, acoustic and optical signals which are generated from a
hollow copper electrode arc plasma torch. In this paper we present details of computations involved in the estimation process
of various dynamic properties and show how they reflect chaotic behavior of arc root in the system. 相似文献
19.
20.