全文获取类型
收费全文 | 6887篇 |
免费 | 1161篇 |
国内免费 | 608篇 |
专业分类
化学 | 1938篇 |
晶体学 | 89篇 |
力学 | 1404篇 |
综合类 | 6篇 |
数学 | 1457篇 |
物理学 | 3762篇 |
出版年
2024年 | 6篇 |
2023年 | 144篇 |
2022年 | 169篇 |
2021年 | 195篇 |
2020年 | 310篇 |
2019年 | 188篇 |
2018年 | 241篇 |
2017年 | 360篇 |
2016年 | 370篇 |
2015年 | 376篇 |
2014年 | 465篇 |
2013年 | 535篇 |
2012年 | 712篇 |
2011年 | 691篇 |
2010年 | 577篇 |
2009年 | 625篇 |
2008年 | 414篇 |
2007年 | 453篇 |
2006年 | 408篇 |
2005年 | 233篇 |
2004年 | 164篇 |
2003年 | 175篇 |
2002年 | 148篇 |
2001年 | 161篇 |
2000年 | 88篇 |
1999年 | 127篇 |
1998年 | 53篇 |
1997年 | 45篇 |
1996年 | 38篇 |
1995年 | 23篇 |
1994年 | 32篇 |
1993年 | 19篇 |
1992年 | 20篇 |
1991年 | 10篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 1篇 |
1984年 | 7篇 |
1983年 | 1篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1979年 | 1篇 |
1971年 | 1篇 |
1957年 | 5篇 |
排序方式: 共有8656条查询结果,搜索用时 15 毫秒
1.
Meccanica - In gear pair actual alternating meshing process, the comprehensive errors of the transmission system and the thermal elastic deformation of the teeth body cause the gears in the meshing... 相似文献
2.
Acta Mechanica Sinica - 相似文献
3.
An adaptive tracking design strategy based on quantized state feedback is developed for uncertain nonholonomic mobile robots with unknown wheel slippage effects. All state variables and control torques are assumed to be quantized by the state and input quantizers, respectively, in a network control environment. Thus, the quantized state feedback information is only available for the tracking control design. An approximation-based adaptive controller using quantized states is recursively designed to ensure the robust adaptive tracking against unknown wheel slippage effects where the quantized-states-based adaptive mechanism is derived to compensate for unknown wheel slippage effects, system nonlinearities, and quantization errors. The boundedness of the quantization errors and estimated parameters in the closed-loop system is analyzed by presenting some theoretical lemmas. Based on these lemmas, we prove the uniform ultimate boundedness of closed-loop signals and the convergence of the trajectory tracking error in the presence of wheel slippage effects. Simulations verify the effectiveness of the resulting tracking scheme. 相似文献
4.
Herein, we successfully construct the 3D biocompatible graphene through crosslinking 2D graphene nanosheet onto carbon fiber paper with poly(diallyldimethylammonium chloride) (PDDA) as anode of the alcohol biofuel cell. Compared with the bioanode without 3D graphene, the current density and output power of PDDA-graphene-ADH bioanode is increased by 23 % and 41 % at a high concentration of ethanol at pH 8.9, suggesting the stabilization role of graphene in enzyme loading. The study provides us a deep analysis on structures and performances of the bioanode incl. electrochemistry, X-ray photoelectron spectra, and atomic force microscopy images, which is significant to develop the new methods to construct 3D porous electrodes in energy conversion device. 相似文献
5.
Zhang Mingjie Song Yang Abdelkefi Abdessattar Yu Haiyan Wang Junlei 《Nonlinear dynamics》2022,108(3):1867-1884
Nonlinear Dynamics - Vortex-induced vibration (VIV) systems with stiffness nonlinearity have received increasing attention because the stiffness nonlinearity can broaden the effective flow velocity... 相似文献
6.
Nonlinear Dynamics - Nonlinear vibration isolation provides with an effective way for vibration reduction with broad band and high efficiency. This investigation focuses on the dynamic effects of a... 相似文献
7.
Fluid Dynamics - The collapse of cavitation bubbles in a hydraulic system generates localized zones of high temperature and pressure and, under certain conditions, luminescence. In this study, we... 相似文献
8.
New ANCF solid-beam element: relationship with Bézier volume and application on leaf spring modeling
Acta Mechanica Sinica - An eight-node solid-beam element based on absolute nodal coordinate formulation (ANCF) which uses cubic interpolation at the longitudinal direction and linear at the... 相似文献
9.
Luo Laizhen Wang Jiamei Zhang Lin Jing Yangping 《International Journal of Theoretical Physics》2021,60(7):2642-2652
International Journal of Theoretical Physics - In this paper, we will consider the exact calculation of differential entropy of induced random state ensemble by partial tracing a subsystem over... 相似文献
10.