全文获取类型
收费全文 | 49843篇 |
免费 | 1683篇 |
国内免费 | 45篇 |
专业分类
化学 | 30271篇 |
晶体学 | 251篇 |
力学 | 851篇 |
综合类 | 1篇 |
数学 | 9691篇 |
物理学 | 10506篇 |
出版年
2023年 | 367篇 |
2022年 | 374篇 |
2021年 | 557篇 |
2020年 | 742篇 |
2019年 | 707篇 |
2018年 | 1026篇 |
2017年 | 933篇 |
2016年 | 1837篇 |
2015年 | 1508篇 |
2014年 | 1472篇 |
2013年 | 3345篇 |
2012年 | 3144篇 |
2011年 | 2996篇 |
2010年 | 1962篇 |
2009年 | 1676篇 |
2008年 | 2578篇 |
2007年 | 2355篇 |
2006年 | 2106篇 |
2005年 | 2110篇 |
2004年 | 1851篇 |
2003年 | 1511篇 |
2002年 | 1323篇 |
2001年 | 996篇 |
2000年 | 993篇 |
1999年 | 691篇 |
1998年 | 540篇 |
1997年 | 463篇 |
1996年 | 617篇 |
1995年 | 430篇 |
1994年 | 504篇 |
1993年 | 454篇 |
1992年 | 497篇 |
1991年 | 412篇 |
1990年 | 465篇 |
1989年 | 372篇 |
1988年 | 381篇 |
1987年 | 339篇 |
1986年 | 336篇 |
1985年 | 469篇 |
1984年 | 437篇 |
1983年 | 335篇 |
1982年 | 335篇 |
1981年 | 358篇 |
1980年 | 287篇 |
1979年 | 282篇 |
1978年 | 276篇 |
1977年 | 266篇 |
1976年 | 281篇 |
1974年 | 258篇 |
1973年 | 267篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
Domokos Szász 《Communications in Mathematical Physics》1992,145(3):595-604
TheK-property is demonstrated for a class of planar billiards satisfying Wojtkowski's principles. Their boundary may consist of convex-scattering, concave and linear pieces. Earlier Wojtkowski showed that these billards had non-zero Lyapunov exponents. 相似文献
132.
Jürgen Kurths M. Carmen Romano Marco Thiel Grigory V. Osipov Mikhail V. Ivanchenko István Z. Kiss John L. Hudson 《Nonlinear dynamics》2006,44(1-4):135-149
We present two different approaches to detect and quantify phase synchronization in the case of coupled non-phase coherent
oscillators. The first one is based on the general idea of curvature of an arbitrary curve. The second one is based on recurrences
of the trajectory in phase space. We illustrate both methods in the paradigmatic example of the R?ssler system in the funnel
regime. We show that the second method is applicable even in the case of noisy data. Furthermore, we extend the second approach
to the application of chains of coupled systems, which allows us to detect easily clusters of synchronized oscillators. In
order to illustrate the applicability of this approach, we show the results of the algorithm applied to experimental data
from a population of 64 electrochemical oscillators. 相似文献
133.
134.
135.
The covering graph of a lattice which is contained in an ordered set with a planar covering graph is itself planar.Presented by R. W. Quackenbush. 相似文献
136.
In this article we prove a local existence and uniqueness theorem for the Kadomtsev-Petviashvili Equation (u
t
+u
xxx
+uu
x
)
x
−u
yy
=0) in the Sobolev spaces of orders≥3, with initial values in the same spaces, and periodic boundary conditions. This theorem improves previous results based
upon the application of singular perturbation techniques. 相似文献
137.
Ferric ferrocyanides synthesized from different sources of ferric cations and ferrocyanide anions and those derived from ferrous ferricyanide, ferrous ferrocyanide and ferric ferricyanide have been studied using Mössbauer and XRD techniques. Structural information of the effect of the provenance on the properties of the final compound is obtained. Significant correlations between isomer shift and quadrupole splitting of inner and outer iron cations have been observed. 相似文献
138.
139.
140.
Dávid Szegvári Romána Zelkó Péter Horváth András Gergely 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):169-172
Enantioselective solubility of rac-norgestrel was found in the presence of γ-cyclodextrin or hydroxypropyl-γ-cyclodextrin.
In both cases the efficacious enantiomer was dissolved in greater extent. Calculating the molar absorptivity and molar ellipticity
spectra of the γ- and hydroxypropyl-γ-cyclodextrin aqueous complexes, a simple and rapid direct circular dichroism (CD) spectrometric
method was obtained for the determination of the enantiomer ratio in aqueous solutions. 相似文献