全文获取类型
收费全文 | 448篇 |
免费 | 26篇 |
国内免费 | 29篇 |
专业分类
化学 | 11篇 |
力学 | 69篇 |
综合类 | 2篇 |
数学 | 337篇 |
物理学 | 84篇 |
出版年
2023年 | 7篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 11篇 |
2019年 | 14篇 |
2018年 | 13篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 21篇 |
2013年 | 32篇 |
2012年 | 15篇 |
2011年 | 28篇 |
2010年 | 18篇 |
2009年 | 31篇 |
2008年 | 36篇 |
2007年 | 39篇 |
2006年 | 18篇 |
2005年 | 19篇 |
2004年 | 27篇 |
2003年 | 14篇 |
2002年 | 11篇 |
2001年 | 16篇 |
2000年 | 11篇 |
1999年 | 14篇 |
1998年 | 13篇 |
1997年 | 11篇 |
1996年 | 11篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1982年 | 3篇 |
排序方式: 共有503条查询结果,搜索用时 15 毫秒
1.
Svitlana P. Rogovchenko 《Journal of Mathematical Analysis and Applications》2003,279(1):121-134
In this paper, we are concerned with a class of nonlinear second-order differential equations with a nonlinear damping term. Passage to more general class of equations allows us to remove a restrictive condition usually imposed on the nonlinearity, and, as a consequence, our results apply to wider classes of nonlinear differential equations. Two illustrative examples are considered. 相似文献
2.
The surgery obstruction of a normal map to a simple Poincaré pair (X, Y) lies in the relative surgery obstruction group L *(π 1(Y) → π 1(X)). A well-known result of Wall, the so-called π-π-theorem, states that in higher dimensions a normal map of a manifold with boundary to a simple Poincaré pair with π 1(X) ? π 1(Y) is normally bordant to a simple homotopy equivalence of pairs. In order to study normal maps to a manifold with a submanifold, Wall introduced the surgery obstruction groups LP * for manifold pairs and splitting obstruction groups LS *. In the present paper, we formulate and prove for manifold pairs with boundary results similar to the π-π-theorem. We give direct geometric proofs, which are based on the original statements of Wall’s results and apply obtained results to investigate surgery on filtered manifolds. 相似文献
3.
用于曲面精密检测的新型光纤三角传感器研究 总被引:1,自引:1,他引:0
基于光纤传感技术和三角测量方法,提出了一种用于曲面检测的新型光纤三角传感器。根据所设计的轮辐式接收光纤结构,可以在测量曲面与传感头间位移时,首先获取被测点处微面元的倾斜信息,以便对传感器测量值进行实时误差修正,从而解决了被测表面倾斜对坐标测量带来的影响。该传感器还能有效地消除环境光干扰、光源波动、表面反射率变化等对测量带来的影响。建立了传感器测量的数学模型。理论分析和初步的实验结果证明了系统的有效性和实用性。该传感器系统不稳定性好于0.3%,横向分辨率好于8μm,高度分辨率好于0.1μm。 相似文献
4.
Let G be a locally compact Abelian group. Following Ruy Exel, we view Fell bundles over the Pontrjagin dual group of G as continuous spectral decompositions of G-actions on C*-algebras. We classify such spectral decompositions using certain dense subspaces related to Marc Rieffel's theory of square-integrability. There is a unique continuous spectral decomposition if the group acts properly on the primitive ideal space of the C*-algebra. But there are also examples of group actions without or with several inequivalent spectral decompositions. 相似文献
5.
The 3-D modeling of heads by using optical triangulation techniques is of great interest in the context of virtual reality, telecommunication and computer animation. This paper presents a structured light-based system mainly for human heads. It is named “3-D Laser Color Scanner” (3DLCS). A 3-D model is obtained with a cylindrical scan. The laser beam is switched on and off using a “light valve” and two successive CCD frames are captured, one with the laser line showing and one without. We can simplify the laser line extracting by subtracting these two images.In this system, two CCD cameras are used to avoid occlusion problems. Color information is read from the CCD when the laser light is absent. Since traditional laser scanner will miss the range data in the low-reflectance areas such as the hair area of human head, a shape from silhouette algorithm is presented to overcome this problem. Finally, we give some results using our system. The resulting model is suitable for many applications. 相似文献
6.
7.
8.
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
9.
Maria Rita Casali 《Acta Appl Math》1998,54(1):75-97
The present paper adopts a computational approach to the study of nonorientable 3-manifolds: in fact, we describe how to create an automaticcatalogue of all nonorientable 3-manifolds admitting coloured triangulationswith a fixed number of tetrahedra. In particular, the catalogue has been effectively produced and analysed for up to 26 tetrahedra, to reach the complete classification of all involved 3-manifolds. As a consequence, the following summarising result can be stated:THEOREM I. Exactly seven closed connected prime nonorientable3-manifolds exist, which admit a coloured triangulation consisting of atmost 26 tetrahedra.More precisely, they are the four Euclidean nonorientable 3-manifolds, the nontrivial S2 bundle overS1, the topological product between thereal projective plane RP2 andS1, and the torus bundle overS1, with monodromy induced by matrix(10 -11). 相似文献
10.
J. M. Borwein J. D. Vanderwerff 《Proceedings of the American Mathematical Society》1996,124(3):751-755
It is shown that the existence of a closed convex set all of whose points are properly supported in a Banach space is equivalent to the existence of a certain type of uncountable ordered one-sided biorthogonal system. Under the continuum hypothesis, we deduce that this notion is weaker than the existence of an uncountable biorthogonal system.