全文获取类型
收费全文 | 1608篇 |
免费 | 299篇 |
国内免费 | 125篇 |
专业分类
化学 | 252篇 |
晶体学 | 20篇 |
力学 | 116篇 |
综合类 | 24篇 |
数学 | 529篇 |
物理学 | 1091篇 |
出版年
2023年 | 15篇 |
2022年 | 32篇 |
2021年 | 40篇 |
2020年 | 30篇 |
2019年 | 36篇 |
2018年 | 27篇 |
2017年 | 36篇 |
2016年 | 48篇 |
2015年 | 39篇 |
2014年 | 89篇 |
2013年 | 113篇 |
2012年 | 76篇 |
2011年 | 100篇 |
2010年 | 96篇 |
2009年 | 124篇 |
2008年 | 116篇 |
2007年 | 87篇 |
2006年 | 107篇 |
2005年 | 94篇 |
2004年 | 80篇 |
2003年 | 82篇 |
2002年 | 66篇 |
2001年 | 47篇 |
2000年 | 44篇 |
1999年 | 49篇 |
1998年 | 50篇 |
1997年 | 38篇 |
1996年 | 34篇 |
1995年 | 28篇 |
1994年 | 22篇 |
1993年 | 19篇 |
1992年 | 17篇 |
1991年 | 15篇 |
1990年 | 18篇 |
1989年 | 9篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 4篇 |
1985年 | 14篇 |
1984年 | 13篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 3篇 |
1973年 | 3篇 |
排序方式: 共有2032条查询结果,搜索用时 15 毫秒
111.
112.
研究了Bloch函数族B中的两个子族Bα与B0,给出了它们的函数之间的关系;作为应用建立了Bα与B0中函数的偏差定理,从而刻画了Bα与B0中函数的有关性质. 相似文献
113.
The boundary charge which constitutes the Virasoro algebra in (2- 1)-dirnensional anti-de Sitter gravity is derived by Noether theorem and diffeomorphic invariance. It shows that the boundary charge under discussion recently exhausts all the available independent nontrivial charges. Therefore, for any specific spacetime, the state counting via the central charge of the Virasoro algebra is exact.`` 相似文献
114.
Recently, a 4-node quadrilateral membrane element AGQ6-I, has been successfully developed for analysis of linear plane problems. Since this model is formulated by the quadrilateral area coordinate method (QACM), a new natural coordinate system for developing quadrilateral finite element models, it is much less sensitive to mesh distortion than other 4-node isoparametric elements and free of various locking problems that arise from irregular mesh geometries. In order to extend these advantages of QACM to nonlinear applications, the total Lagrangian (TL) formulations of element AGQ6-I was established in this paper, which is also the first time that a plane QACM element being applied in the implicit geometrically nonlinear analysis. Numerical examples of geometrically nonlinear analysis show that the presented formulations can prevent loss of accuracy in severely distorted meshes, and therefore, are superior to those of other 4-node isoparametric elements. The efficiency of QACM for developing simple, effective and reliable serendipity plane membrane elements in geometrically nonlinear analysis is demonstrated clearly. 相似文献
115.
In previous work we have shown that classical approximation theory provides methods for the systematic construction of inverse-closed smooth subalgebras. Now we extend this work to treat inverse-closed subalgebras of ultradifferentiable elements. In particular, Carleman classes and Dales–Davie algebras are treated. As an application the result of Demko, Smith and Moss, and Jaffard on the inverse of a matrix with exponential decay is obtained within the framework of a general theory of smoothness. 相似文献
116.
In this paper, we present a geometric approach for computing controlled invariant sets for hybrid control systems. While the problem is well studied in the ellipsoidal case, this family is quite conservative for constrained or switched linear systems. We reformulate the invariance of a set as an inequality for its support function that is valid for any convex set. This produces novel algebraic conditions for the invariance of sets with polynomial or piecewise quadratic support functions. 相似文献
117.
Tsutomu Asano Shota Sano Toshihiko Okabe Takumi Sano Chie Sawatari 《Journal of Macromolecular Science: Physics》2018,57(5):317-332
Using a modified method developed from Vonk's method, detailed values of crystallinity and crystal disorder were obtained by wide angle X-ray diffraction (WAXD). In Vonk's method, the crystallinity (w) is determined by extrapolation of the WAXD experimental curve back to zero scattering angle, while the distortion factor (k) is determined by the inclination of the experimental curve at zero scattering angle. In our new method, both w and k are determined at the same time by using the least squares method. In order to show the efficiency of our method, the new fitting procedure was applied to the experimental values of polyethylene and polyethylene terephthalate as measured by Vonk, and the values of w and k determined by our new method were compared with those found by Vonk's method. The new fitting method has the advantage that it uses the whole experimental curve. Moreover, our modified Vonk's method enables us to discuss crystal distortions as arising from first-kind (thermal) disorder and second-kind (paracrystalline) disorder. 相似文献
118.
In this paper, we obtain the strong comparison principle and Hopf Lemma for locally Lipschitz viscosity solutions to a class of nonlinear degenerate elliptic operators of the form ▽~2ψ + L(x, ▽ψ), including the conformal hessian operator. 相似文献
119.
120.
The distortion property of hyperbolic area of planar quasiconformal mappings is studied in this paper.In the case of radial quasiconformal mappings and angular deformed quasiconformal mappings their hyperbolic area distortions are estimated quite sharply.The result can be applied to judge whether the hyperbolic area of a planar subset is explodable. 相似文献