全文获取类型
收费全文 | 7842篇 |
免费 | 214篇 |
国内免费 | 356篇 |
专业分类
化学 | 1735篇 |
晶体学 | 87篇 |
力学 | 61篇 |
综合类 | 24篇 |
数学 | 5562篇 |
物理学 | 943篇 |
出版年
2023年 | 28篇 |
2022年 | 70篇 |
2021年 | 64篇 |
2020年 | 68篇 |
2019年 | 198篇 |
2018年 | 205篇 |
2017年 | 96篇 |
2016年 | 107篇 |
2015年 | 105篇 |
2014年 | 200篇 |
2013年 | 473篇 |
2012年 | 244篇 |
2011年 | 430篇 |
2010年 | 387篇 |
2009年 | 512篇 |
2008年 | 638篇 |
2007年 | 624篇 |
2006年 | 554篇 |
2005年 | 372篇 |
2004年 | 345篇 |
2003年 | 292篇 |
2002年 | 257篇 |
2001年 | 176篇 |
2000年 | 197篇 |
1999年 | 224篇 |
1998年 | 200篇 |
1997年 | 141篇 |
1996年 | 183篇 |
1995年 | 175篇 |
1994年 | 169篇 |
1993年 | 137篇 |
1992年 | 99篇 |
1991年 | 61篇 |
1990年 | 42篇 |
1989年 | 41篇 |
1988年 | 38篇 |
1987年 | 24篇 |
1986年 | 18篇 |
1985年 | 34篇 |
1984年 | 26篇 |
1983年 | 11篇 |
1982年 | 17篇 |
1981年 | 18篇 |
1980年 | 16篇 |
1979年 | 23篇 |
1978年 | 13篇 |
1977年 | 19篇 |
1976年 | 9篇 |
1975年 | 11篇 |
1973年 | 11篇 |
排序方式: 共有8412条查询结果,搜索用时 31 毫秒
131.
132.
Sergio Albeverio Volodymyr Koshmanenko Mykola Pratsiovytyi Grygoriy Torbin 《Positivity》2006,10(1):39-49
We introduce the conflict interaction with two positions between a couple of image probability measures and consider the associated
dynamical system. We prove the existence of invariant limiting measures and find the criteria for these measures to be a pure
point, absolutely continuous, or singular cotinuous as well as to have any topological type and arbitary Hausdorff dimension. 相似文献
133.
134.
The first object of this paper is to introduce a new evolution equation for the characteristic function of the boundary Γ
of a Lipschitzian domain Ω in the N-dimensional Euclidean space under the influence of a smooth time-dependent velocity field. The originality of this equation is that the evolution takes place in an Lp-space with respect to the (N − 1)-Hausdorff measure. A second more speculative objective is to discuss how that equation can be relaxed to rougher velocity
fields via some weak formulation. A candidate is presented and some of the technical difficulties and open issues are discussed.
Continuity results in several metric topologies are also presented. The paper also specializes the results on the evolution
of the oriented distance function to initial sets with zero N-dimensional Lebesgue measure. 相似文献
135.
Aiden A. Bruen 《Acta Appl Math》2006,93(1-3):179-196
We survey some applications of finite fields to finite geometries in part A and to combinatorics and error-correcting codes in parts B and C. 相似文献
136.
Cheng Lu ZHANG Xiao Lei ZHU Ying Ge MA Li Wei ZOU 《中国化学快报》2006,17(2):163-164
12-Hydroxy-13-methylpodocarpa-9, 11, 13-trien-3-one 9 was isolated from the twigs ofCroton salutaris1. Many diterpenes exhibit significant bioactivities, such as antibac-terial and antitumour and 9 has a rare structure. In order to study the relationshipb… 相似文献
137.
Toshiyuki Oyama Akira Kitamura Eiichi Sato Masao Tomoi 《Journal of polymer science. Part A, Polymer chemistry》2006,44(8):2694-2706
The factors affecting pattern‐forming properties in reaction development patterning were examined with polyarylates with various bisphenol moieties. The developability of the photosensitive polyarylates was dependent on the properties of the subtituent (R) in the bisphenol moieties. The development time decreased in the following order: R?C(CH3)2 > fluorenyl unit ? phenolphthalein unit > C(CF3)2 > SO2. This order agreed with that of the reactivity between the polyarylates and ethanolamine, and these orders can be explained by pKa of the bisphenol used to prepare the polyarylates. The development with NH2? R′? OH resulted in successful positive‐tone pattern formation. However, pattern formation with the developers containing NH2? R′? OCH3 was unsuccessful. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2694–2706, 2006 相似文献
138.
In this paper we study the stability of transonic shocks in steady supersonic flow past a wedge. We take the potential flow equation as the mathematical model to describe the compressible flow. It is known that in generic case such a problem admits two possible location of shock, connecting the flow ahead it and behind it. They can be distinguished as supersonic-supersonic shock and supersonic-subsonic shock (or transonic shock). Both these possible shocks satisfy the Rankine-Hugoniot conditions and entropy condition. In this paper we prove that the transonic shock is also stable under perturbation of the coming flow provided the pressure at infinity is well controlled. 相似文献
139.
Some bounds on the entries and on the norm of the inverse of triangular matrices with nonnegative and monotone entries are found. All the results are obtained by exploiting the properties of the fundamental matrix of the recurrence relation which generates the sequence of the entries of the inverse matrix. One of the results generalizes a theorem contained in a recent article of one of the authors about Toeplitz matrices. 相似文献
140.
Various topological properties of projective duality between real projective varieties and their duals are obtained by making use of the microlocal theory of (subanalytically) constructible sheaves developed by Kashiwara [M. Kashiwara, Index theorem for constructible sheaves, Astérisque 130 (1985) 193-209] and Kashiwara-Schapira [M. Kashiwara, P. Schapira, Sheaves on Manifolds, Grundlehren Math. Wiss., vol. 292, Springer, Berlin-Heidelberg-New York, 1990]. In particular, we prove in the real setting some results similar to the ones proved by Ernström in the complex case [L. Ernström, Topological Radon transforms and the local Euler obstruction, Duke Math. J. 76 (1994) 1-21]. For this purpose, we describe the characteristic cycles of topological Radon transforms of constructible functions in terms of curvatures of strata in real projective spaces. 相似文献