全文获取类型
收费全文 | 213篇 |
免费 | 69篇 |
国内免费 | 25篇 |
专业分类
化学 | 12篇 |
力学 | 131篇 |
数学 | 8篇 |
物理学 | 156篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 8篇 |
2018年 | 2篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 8篇 |
2014年 | 14篇 |
2013年 | 9篇 |
2012年 | 14篇 |
2011年 | 31篇 |
2010年 | 13篇 |
2009年 | 10篇 |
2008年 | 15篇 |
2007年 | 14篇 |
2006年 | 30篇 |
2005年 | 13篇 |
2004年 | 14篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 11篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有307条查询结果,搜索用时 437 毫秒
301.
《Communications in Nonlinear Science & Numerical Simulation》2014,19(12):4196-4212
This study presents a direct comparison of measured and predicted nonlinear vibrations of a clamped–clamped steel beam with non-ideal boundary conditions. A multi-harmonic comparison of simulations with measurements is performed in the vicinity of the primary resonance. First of all, a nonlinear analytical model of the beam is developed taking into account non-ideal boundary conditions. Three simulation methods are implemented to investigate the nonlinear behavior of the clamped–clamped beam. The method of multiple scales is used to compute an analytical expression of the frequency response which enables an easy updating of the model. Then, two numerical methods, the Harmonic Balance Method and a time-integration method with shooting algorithm, are employed and compared one with each other. The Harmonic Balance Method enables to simulate the vibrational stationary response of a nonlinear system projected on several harmonics. This study then proposes a method to compare numerical simulations with measurements of all these harmonics. A signal analysis tool is developed to extract the system harmonics’ frequency responses from the temporal signal of a swept sine experiment. An evolutionary updating algorithm (Covariance Matrix Adaptation Evolution Strategy), coupled with highly selective filters is used to identify both fundamental frequency and harmonic amplitudes in the temporal signal, at every moment. This tool enables to extract the harmonic amplitudes of the output signal as well as the input signal. The input of the Harmonic Balance Method can then be either an ideal mono-harmonic signal or a multi-harmonic experimental signal. Finally, the present work focuses on the comparison of experimental and simulated results. From experimental output harmonics and numerical simulations, it is shown that it is possible to distinguish the nonlinearities of the clamped–clamped beam and the effect of the non-ideal input signal. 相似文献
302.
Isotopic production cross sections of fragmentation residues produced by 18O ions on a carbon target near 260 MeV/nucleon
下载免费PDF全文
![点击此处可从《中国物理C(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Xiao-Dong Xu Ya-Zhou Sun Shi-Tao Wang Bo Mei Shu-Ya Jin Xue-Heng Zhang Zhi-Yu Sun Yi-Xuan Zhao Shu-Wen Tang Yu-Hong Yu Duo Yan Fang Fang Yong-Jie Zhang Shao-Bo Ma 《中国物理C(英文版)》2022,46(11):111001-111001-6
The isotopic cross sections of residual nuclei produced in fragmentation reactions of 18O projectiles impinging on a carbon target at energies near 260 MeV/nucleon were measured at the HIRFL facility in Lanzhou (China). A full identification of atomic and mass numbers of fragments was achieved from the determination of their magnetic rigidity, energy loss, and time of flight. The production cross sections for a dozen of nitrogen, carbon, and boron isotopes were determined with uncertainties below 30% for most of the cases. The obtained cross sections for N and B isotopes show a rather good agreement with previous experimental data obtained with different projectile energies. The cross sections for some C isotopes seem to exhibit a dependence on the projectile energy. A comparison of the data and several theoretical model calculations are presented. 相似文献
303.
Molecular ion yield enhancement induced by gold deposition in static secondary ion mass spectrometry
Static ToF-SIMS was used to evaluate the effect of gold condensation as a sample treatment prior to analysis. The experiments were carried out with a model molecular layer (Triacontane M = 422.4 Da), upon atomic (In+) and polyatomic (Bi3+) projectile bombardment. The results indicate that the effect of molecular ion yield improvement using gold metallization exists only under atomic projectile impact. While the quasi-molecular ion (M+Au)+ signal can become two orders of magnitude larger than that of the deprotonated molecular ion from the pristine sample under In+ bombardment, it barely reaches the initial intensity of (M−H)+ when Bi3+ projectiles are used. The differences observed for mono- and polyatomic primary ion bombardment might be explained by differences in near-surface energy deposition, which influences the sputtering and ionization processes. 相似文献
304.
The cross sections of the fragments produced in the projectile fragmentation reactions of the even calcium isotopes from A=36 to A=52 are calculated using the statistical abrasion ablation model.The neutron skin thickness are studied by investigating the fragments isotopic cross section distributions.The neutron-skin thicknesses of the calcium isotopes have a good linear correlation to the peak positions of their fragment isotopic cross section distributions.The correlation between the neutron skin thickness and the neutron density distributions of 48Ca is investigated by introducing a parameter to adjust the diffuseness parameter in the fermi-type density distribution. 相似文献
305.
306.
307.
In this paper, we consider the problem of expansion of a non-ideal gas turning around corresponding large or small sharp corner for 2-D compressible Euler system. We focus on extending the results of this problem for polytropic gas to that for a more realistic gas, that is, van der Waals gas. In this case, rarefaction waves, shock wave, fan–jump composite waves, or fan–jump–fan composite waves may be appeared. The flow expands to vacuum state when the inclination angle is small enough, that is, a zone of cavitation will come into being. Otherwise, the flow will arrive at a zone of constant state. The corresponding problem can be transformed into interaction of a planar rarefaction wave with a planar centered wave and interaction of a simple wave with rigid wall, which are actually characteristic boundary value problems for 2-D self-similar Euler system. The estimates of solution are obtained by making use of characteristic analysis, corresponding characteristic decompositions and invariant region of solution. Furthermore, by extending the local solution, and combining with those estimates and hyperbolicity, the existence of global classical solution up to the interface of non-ideal gas with vacuum is obtained. 相似文献