全文获取类型
收费全文 | 4215篇 |
免费 | 136篇 |
国内免费 | 129篇 |
专业分类
化学 | 547篇 |
晶体学 | 9篇 |
力学 | 413篇 |
综合类 | 13篇 |
数学 | 727篇 |
物理学 | 1831篇 |
综合类 | 940篇 |
出版年
2024年 | 7篇 |
2023年 | 24篇 |
2022年 | 53篇 |
2021年 | 65篇 |
2020年 | 53篇 |
2019年 | 107篇 |
2018年 | 84篇 |
2017年 | 137篇 |
2016年 | 154篇 |
2015年 | 142篇 |
2014年 | 372篇 |
2013年 | 272篇 |
2012年 | 149篇 |
2011年 | 230篇 |
2010年 | 205篇 |
2009年 | 255篇 |
2008年 | 241篇 |
2007年 | 217篇 |
2006年 | 230篇 |
2005年 | 205篇 |
2004年 | 212篇 |
2003年 | 191篇 |
2002年 | 163篇 |
2001年 | 86篇 |
2000年 | 60篇 |
1999年 | 69篇 |
1998年 | 78篇 |
1997年 | 72篇 |
1996年 | 32篇 |
1995年 | 34篇 |
1994年 | 16篇 |
1993年 | 23篇 |
1992年 | 23篇 |
1991年 | 14篇 |
1990年 | 21篇 |
1989年 | 23篇 |
1988年 | 21篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1982年 | 6篇 |
1981年 | 16篇 |
1980年 | 16篇 |
1979年 | 6篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 10篇 |
1974年 | 6篇 |
排序方式: 共有4480条查询结果,搜索用时 15 毫秒
1.
《Indagationes Mathematicae》2021,32(1):55-85
We show that the differential structure of the orbit space of a proper action of a Lie group on a smooth manifold is weakly reflexive. This implies that the orbit space is a differentiable space in the sense of Smith, which ensures that the orbit space has an exterior algebra of differential forms, that satisfies Smith’s version of de Rham’s theorem. Because the orbit space is a locally closed subcartesian space, it has vector fields and their flows. 相似文献
2.
3.
《Comptes Rendus Physique》2015,16(2):193-203
The field of multiferroics has experienced a rapid progress resulting in the discovery of many new physical phenomena. BiFeO3 (BFO) compound, which is one of the few room-temperature single-phase multiferroics, has contributed subsequently to this progress. As a result, significant review articles have been devoted specifically to this famous system. This chapter is dedicated to the strain effects on the structure stability and property changes of BFO thin films. It is a short and non-exhaustive topical overview that may be seen as an invitation for interested readers to go beyond. There is a very active and prolific research in this field and we apologize to the authors whose relevant work is not cited here. After a short introduction, we will thus review the effect of strain on BFO films by describing the consequences on the structure and the phase transitions as well as on polar, magnetic and magnetoelectric properties. 相似文献
4.
《Comptes Rendus Mecanique》2019,347(4):318-331
In this essay we explore analogies between macroscopic patterns, which result from a sequence of phase transitions/instabilities starting from a homogeneous state, and similar phenomena in cosmology, where a sequence of phase transitions in the early universe is believed to have separated the fundamental forces from each other, and also shaped the structure and distribution of matter in the universe. We discuss three distinct aspects of this analogy: (i) Defects and topological charges in macroscopic patterns are analogous to spins and charges of quarks and leptons; (ii) Defects in generic 3+1 stripe patterns carry an energy density that accounts for phenomena that are currently attributed to dark matter; (iii) Space-time patterns of interacting nonlinear waves display behaviors reminiscent of quantum phenomena including inflation, entanglement and dark energy. 相似文献
5.
《Comptes Rendus Mecanique》2019,347(4):287-293
I will shortly review the history of experimental and theoretical findings on period doubling until the discovery of the quantitative universal properties of the infinite period-doubling cascade. 相似文献
6.
李宁 《科技情报开发与经济》2004,14(9):158-159
通过对会计责任与审计责任的概念剖析和会计责任、审计责任界定的国际比较,揭示了会计责任与审计责任在实务中难以界定的原因,指出只有明晰两种责任,才能促进企业的发展和保护注册会计师以及事务所的合法权益。 相似文献
7.
陈子国 《阜阳师范学院学报(自然科学版)》2002,19(1):59-61
本文重点介绍了集成有源负载放大器的分析方法,并以镜像电流源为例详细介绍、对比了两种方法(图解分析法和微变等效电路分析法)。此外,介绍了用厄雷电压计算 Av 的简便方法。 相似文献
8.
A tomographic reconstruction method based on Monte Carlo random searching guided by the information contained in the projections
of radiographed objects is presented. In order to solve the optimization problem, a multiscale algorithm is proposed to reduce
computation. The reconstruction is performed in a coarse-to-fine multigrid scale that initializes each resolution level with
the reconstruction of the previous coarser level, which substantially improves the performance. The method was applied to
a real case reconstructing the internal structure of a small metallic object with internal components, showing excellent results. 相似文献
9.
岳秀芳 《温州大学学报(自然科学版)》2008,(2):113-116
影片《图雅的婚事》是导演由纯个人化表达向电影故事性转变的探索,因此更注重电影叙事表达和影像表意性。影片贴近于普通人的现实生活,表现真实的生活质感,赞扬人类面对无奈命运时自我救赎的乐观坚忍精神。 相似文献
10.
本文提出从高分辨电子显微像中,利用光学、全息和部分相干等方法,提取传递函数,制作相位和振幅滤波器,实现解卷,提高高分辨电子显微像的分辨率. 相似文献