全文获取类型
收费全文 | 276篇 |
免费 | 30篇 |
国内免费 | 31篇 |
专业分类
化学 | 175篇 |
晶体学 | 2篇 |
力学 | 17篇 |
综合类 | 1篇 |
数学 | 57篇 |
物理学 | 85篇 |
出版年
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 18篇 |
2014年 | 12篇 |
2013年 | 20篇 |
2012年 | 20篇 |
2011年 | 18篇 |
2010年 | 17篇 |
2009年 | 16篇 |
2008年 | 23篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 8篇 |
2000年 | 4篇 |
1999年 | 16篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1990年 | 5篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1969年 | 2篇 |
1968年 | 1篇 |
1929年 | 1篇 |
1909年 | 1篇 |
1887年 | 1篇 |
排序方式: 共有337条查询结果,搜索用时 31 毫秒
121.
122.
Li S Zhang C Wang M Luo HQ Lu X Faulhaber E Schneidewind A Link P Hu J Xiang T Dai P 《Physical review letters》2010,105(15):157002
We use cold neutron spectroscopy to study the low-energy spin excitations of superconducting (SC) FeSe0.4Te0.6 and essentially nonsuperconducting (NSC) FeSe0.45Te0.55. In contrast with BaFe2-x(Co,Ni)xAs2, where the low-energy spin excitations are commensurate both in the SC and normal state, the normal-state spin excitations in SC FeSe0.4Te0.6 are incommensurate and show an hourglass dispersion near the resonance energy. Since similar hourglass dispersion is also found in the NSC FeSe0.45Te0.55, we argue that the observed incommensurate spin excitations in FeSe(1-x)Tex are not directly associated with superconductivity. Instead, the results can be understood within a picture of Fermi surface nesting assuming extremely low Fermi velocities and spin-orbital coupling. 相似文献
123.
Anomalous large thermal conductivity has been observed numerically and experimentally in one- and two-dimensional systems. There is an open debate about the role of conservation of momentum. We introduce a model whose thermal conductivity diverges in dimensions 1 and 2 if momentum is conserved, while it remains finite in dimension d > or = 3. We consider a system of harmonic oscillators perturbed by a nonlinear stochastic dynamics conserving momentum and energy. We compute explicitly the time correlation function of the energy current C(J)(t), and we find that it behaves, for large time, like t(-d/2) in the unpinned cases, and like t(-d/2-1) when an on-site harmonic potential is present. This result clarifies the role of conservation of momentum in the anomalous thermal conductivity in low dimensions. 相似文献
124.
125.
126.
Giada Basile Stefano Olla Herbert Spohn 《Archive for Rational Mechanics and Analysis》2010,195(1):171-203
We consider lattice dynamics with a small stochastic perturbation of order ${\varepsilon}We consider lattice dynamics with a small stochastic perturbation of order e{\varepsilon} and prove that for a space–time scale of order e-1{\varepsilon^{-1}} the local spectral density (Wigner function) evolves according to a linear transport equation describing inelastic collisions.
For an energy and momentum conserving chain, the transport equation predicts a slow decay, as 1/?t{1/\sqrt t} , for the energy current correlation in equilibrium. This is in agreement with previous studies using a different method. 相似文献
127.
Effect of carbonitride precipitates on the abrasive wear behaviour of hardfacing alloy 总被引:4,自引:0,他引:4
Hardfacing alloy of martensitic stainless steel expect higher abradability to be achieved through the addition of nitrogen being provided by the fine scale precipitation of complex carbonitride particles. Niobium and titanium as the most effective carbonitride alloying elements were added in the Fe–Cr13–Mn–N hardfacing alloy to get carbonitride precipitates. Carbonitride was systematically studied by optical microscopy, scanning electronic microscopy and energy spectrum analysis. Abrasive wear resistance of hardfacing alloy in as-welded and heat-treated conditions was tested by using the belt abrasion test apparatus where the samples slide against the abrasive belt. It is found that carbonitride particles in the hardfacing alloy are complex of Cr, Ti and Nb distributing on the grain boundary or matrix of the hardfacing alloy with different number and size in as-welded and heat-treated conditions. A large number of carbonitrides can be precipitated with very fine size (nanoscale) after heat treatment. As a result, the homogeneous distribution of very fine carbonitride particles can significantly improve the grain-abrasion wear-resisting property of the hardfacing alloy, and the mass loss is plastic deformation with minimum depth of grooving by abrasive particles and fine delamination. 相似文献
128.
Qianqian Wu Zongbing Chen Jian Xiong Zhenyu Wang Chenglin Yang 《Acta Mechanica Solida Sinica》2021,34(4):477-493
This paper looks into the effects of various porous structures used in the construc-tion of the shell of a protective helmet on the energy absorption capacity a... 相似文献
129.
Neurodegenerative diseases, such as Alzheimer′s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), currently represent major unmet medical needs. Therefore, novel therapeutic strategies are needed in order to improve patients’ quality of life and prognosis. Since oxidative stress can be strongly involved in neurodegenerative diseases, the potential use of inosine, known for its antioxidant properties, in this context deserves particular attention. The protective action of inosine treatment could be mediated by its metabolite urate. Here, we review the current preclinical and clinical studies investigating the use of inosine in AD, PD, ALS, and MS. The most important properties of inosine seem to be its antioxidant action and its ability to raise urate levels and to increase energetic resources by improving ATP availability. Inosine appears to be generally safe and well tolerated; however, the possible formation of kidney stones should be monitored, and data on its effectiveness should be further explored since, so far, they have been controversial. Overall, inosine could be a promising potential strategy in the management of neurodegenerative diseases, and additional studies are needed in order to further investigate its safety and efficacy and its use as a complementary therapy along with other approved drugs. 相似文献
130.