全文获取类型
收费全文 | 3504篇 |
免费 | 73篇 |
国内免费 | 19篇 |
专业分类
化学 | 2296篇 |
晶体学 | 27篇 |
力学 | 121篇 |
数学 | 508篇 |
物理学 | 644篇 |
出版年
2023年 | 20篇 |
2022年 | 65篇 |
2021年 | 78篇 |
2020年 | 49篇 |
2019年 | 51篇 |
2018年 | 52篇 |
2017年 | 40篇 |
2016年 | 81篇 |
2015年 | 75篇 |
2014年 | 90篇 |
2013年 | 186篇 |
2012年 | 175篇 |
2011年 | 231篇 |
2010年 | 148篇 |
2009年 | 132篇 |
2008年 | 222篇 |
2007年 | 204篇 |
2006年 | 218篇 |
2005年 | 188篇 |
2004年 | 175篇 |
2003年 | 133篇 |
2002年 | 139篇 |
2001年 | 56篇 |
2000年 | 52篇 |
1999年 | 35篇 |
1998年 | 37篇 |
1997年 | 35篇 |
1996年 | 54篇 |
1995年 | 40篇 |
1994年 | 33篇 |
1993年 | 28篇 |
1992年 | 15篇 |
1991年 | 23篇 |
1990年 | 25篇 |
1989年 | 33篇 |
1988年 | 28篇 |
1987年 | 24篇 |
1986年 | 24篇 |
1985年 | 27篇 |
1984年 | 31篇 |
1983年 | 25篇 |
1982年 | 28篇 |
1981年 | 25篇 |
1980年 | 23篇 |
1979年 | 16篇 |
1978年 | 26篇 |
1977年 | 16篇 |
1976年 | 12篇 |
1975年 | 15篇 |
1967年 | 7篇 |
排序方式: 共有3596条查询结果,搜索用时 46 毫秒
1.
2.
3.
AbstractRealistic stochastic modeling is increasingly requiring the use of bounded noises. In this work, properties and relationships of commonly employed bounded stochastic processes are investigated within a solid mathematical ground. Four families are object of investigation: the Sine-Wiener (SW), the Doering–Cai–Lin (DCL), the Tsallis–Stariolo–Borland (TSB), and the Kessler–Sørensen (KS) families. We address mathematical questions on existence and uniqueness of the processes defined through Stochastic Differential Equations, which often conceal non-obvious behavior, and we explore the behavior of the solutions near the boundaries of the state space. The expression of the time-dependent probability density of the Sine-Wiener noise is provided in closed form, and a close connection with the Doering–Cai–Lin noise is shown. Further relationships among the different families are explored, pathwise and in distribution. Finally, we illustrate an analogy between the Kessler–Sørensen family and Bessel processes, which allows to relate the respective local times at the boundaries. 相似文献
4.
5.
6.
7.
8.
L. Torrisi A.M. Mezzasalma J. Badziak J. Wolowski G. Franco 《Applied Surface Science》2006,252(24):8533-8538
High energy laser plasma-produced Cu ions have been implanted in silicon substrates placed at different distances and angles with respect to the normal to the surface of the ablated target. The implanted samples have been produced using the iodine high power Prague Asterix Laser System (PALS) using 438 nm wavelength irradiating in vacuum a Cu target. The high laser pulse energy (up to 230 J) and the short pulse duration (400 ps) produced a non-equilibrium plasma expanding mainly along the normal to the Cu target surface. Time-of-flight (TOF) technique was employed, through an electrostatic ion energy analyzer (IEA) placed along the target normal, in order to measure the ion energy, the ion charge state, the energy distribution and the charge state distribution. Ions had a Boltzmann energy distributions with an energy increasing with the charge state. At a laser fluence of the order of 6 × 106 J/cm2, the maximum ion energy was about 600 keV and the maximum charge state was about 27+.In order to investigate the implantation processes, Cu depth profiles have been performed with Rutherford backscattering spectrometry (RBS) of 1.5 MeV helium ions, Auger electron spectroscopy (AES) with 3 keV electron beam and 1 keV Ar sputtering ions in combination with scanning electron microscopy (SEM). Surface analysis results indicate that Cu ions are implanted within the first surface layers and that the ion penetration ranges are in agreement with the ion energy measured with IEA analysis. 相似文献
9.
Daniel FRANCO Gennaro INFANTE Donal O'REGAN 《数学学报(英文版)》2006,22(6):1745-1750
We establish new criteria for the existence of either positive or nonzero solutions of the Urysohn integral equation. We also discuss the existence of an interval of positive eigenvalues and sufficient conditions for the existence of at least a positive eigenvalue with a nonzero or positive eigenfunction for the Urysohn integral operator. Among others, we employ techniques based on fixed point index theory for compact maps, which are new for this type of equation. 相似文献
10.
Nicola Arcozzi Enrico Casadio Tarabusi Fausto Di Biase Massimo A. Picardello 《Transactions of the American Mathematical Society》2006,358(6):2781-2798
We establish a potential theoretic approach to the study of twist points in the boundary of simply connected planar domains.