全文获取类型
收费全文 | 10207篇 |
免费 | 281篇 |
国内免费 | 266篇 |
专业分类
化学 | 1021篇 |
晶体学 | 25篇 |
力学 | 101篇 |
综合类 | 23篇 |
数学 | 8618篇 |
物理学 | 966篇 |
出版年
2023年 | 31篇 |
2022年 | 49篇 |
2021年 | 52篇 |
2020年 | 58篇 |
2019年 | 282篇 |
2018年 | 296篇 |
2017年 | 163篇 |
2016年 | 131篇 |
2015年 | 124篇 |
2014年 | 328篇 |
2013年 | 689篇 |
2012年 | 380篇 |
2011年 | 601篇 |
2010年 | 536篇 |
2009年 | 794篇 |
2008年 | 825篇 |
2007年 | 794篇 |
2006年 | 609篇 |
2005年 | 418篇 |
2004年 | 347篇 |
2003年 | 310篇 |
2002年 | 269篇 |
2001年 | 236篇 |
2000年 | 182篇 |
1999年 | 237篇 |
1998年 | 198篇 |
1997年 | 132篇 |
1996年 | 220篇 |
1995年 | 197篇 |
1994年 | 205篇 |
1993年 | 161篇 |
1992年 | 131篇 |
1991年 | 85篇 |
1990年 | 76篇 |
1989年 | 62篇 |
1988年 | 41篇 |
1987年 | 47篇 |
1986年 | 40篇 |
1985年 | 52篇 |
1984年 | 61篇 |
1983年 | 23篇 |
1982年 | 47篇 |
1981年 | 61篇 |
1980年 | 44篇 |
1979年 | 26篇 |
1978年 | 24篇 |
1977年 | 24篇 |
1976年 | 25篇 |
1974年 | 12篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Xiao-Hong Xu Xiao-Li Li Fang Wang Feng-Xian Jiang Hai-Shun Wu 《Applied Surface Science》2006,252(8):2910-2914
FexPt100−x(30 nm) and [FexPt100−x(3 nm)/ZrO2]10 (x = 37, 48, 57, 63, 69) films with different ZrO2 content were prepared by RF magnetron sputtering technique, then were annealed at 550 °C for 30 min. This work investigates the effect of ZrO2 doping on the microstructural evolution, magnetic properties, grain size, as well as the ordering kinetics of FePt alloy films. The as-deposited films behaved a disordered state, and the ordered L10 structure was obtained by post-annealing. The magnetic properties of the films are changed from soft magnetism to hard magnetism after annealing. The variation of the largest coercivities of [FexPt100−x/ZrO2]10 films with the Fe atomic percentage, x and differing amounts of ZrO2 content reveals that as we increase the ZrO2 content we must correspondingly increase the amount of Fe. This phenomenon suggests that the Zr or O atoms of ZrO2 preferentially react with the Fe atoms of FePt alloy to form compounds. In addition, introducing the nonmagnetic ZrO2 can reduce the intergrain exchange interactions of the FePt/ZrO2 films, and the interactions are decreased as the ZrO2 content increases, the dipole interactions are observed in FePt/ZrO2 films as the ZrO2 content is more than 15%. 相似文献
52.
Piotr Ko?cielniak 《Topology and its Applications》2007,154(9):1951-1955
Let M be a compact manifold with dimM?2. We prove that some iteration of the generic homeomorphism on M is semiconjugated to the shift map and has infinite topological entropy (Theorem 1.1). 相似文献
53.
Teruhisa Tsuda 《Letters in Mathematical Physics》2006,77(1):21-30
Starting from certain point sets in the projective plane, we construct a tropical (or subtraction-free birational) representation of Weyl groups over the field of τ-functions. In particular, our construction includes E
8
(1)
, E
7
(1)
, E
6
(1)
and D
5
(1)
as affine cases; each of them gives rise to the q-difference Painlevé equation. 相似文献
54.
Paul Fabel 《Topology and its Applications》2007,154(3):635-638
With a certain natural topology, the fundamental group of a locally path connected metric space X becomes discrete if and only if X is semilocally simply connected. We include some related material and offer a counterexample to a similar result. 相似文献
55.
We study the inverse scattering problem for the nonlinear Schrödinger equation and for the nonlinear Klein–Gordon equation with the generalized Hartree type nonlinearity. We reconstruct the nonlinearity from knowledge of the scattering operator, which improves the known results. 相似文献
56.
采用光学显微镜和扫描电子显微镜等手段,对某轻型汽车40Cr后桥半轴断裂件的组织及断口特征进行了分析结果表明:半轴在调质处理时的淬火温度不够高,使其表层和心部组织中存在较多的铁素体相,造成了工件最终的硬度和疲劳强度不足,导致半轴在使用中发生扭转疲劳断裂. 相似文献
57.
Hirofumi Tsumura 《Journal of Number Theory》2004,106(1):155-168
In this paper, we define the multiple Euler numbers and consider some multiple harmonic series of Mordell-Tornheim's type, which is a partial sum of the Mordell-Tornheim zeta series defined by Matsumoto. Indeed, we prove a certain reducibility of these series as well as the multiple zeta values. 相似文献
58.
Luc Miller 《Bulletin des Sciences Mathématiques》2005,129(2):175-185
We make two remarks about the null-controllability of the heat equation with Dirichlet condition in unbounded domains. Firstly, we give a geometric necessary condition (for interior null-controllability in the Euclidean setting) which implies that one cannot go infinitely far away from the control region without tending to the boundary (if any), but also applies when the distance to the control region is bounded. The proof builds on heat kernel estimates. Secondly, we describe a class of null-controllable heat equations on unbounded product domains. Elementary examples include an infinite strip in the plane controlled from one boundary and an infinite rod controlled from an internal infinite rod. The proof combines earlier results on compact manifolds with a new lemma saying that the null-controllability of an abstract control system and its null-controllability cost are not changed by taking its tensor product with a system generated by a non-positive self-adjoint operator. 相似文献
59.
In this paper we obtain some metrics results about large partial quotients in the continued fraction expansion. 相似文献
60.