全文获取类型
收费全文 | 297篇 |
免费 | 25篇 |
专业分类
化学 | 171篇 |
晶体学 | 1篇 |
力学 | 7篇 |
数学 | 74篇 |
物理学 | 69篇 |
出版年
2023年 | 9篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 26篇 |
2019年 | 32篇 |
2018年 | 14篇 |
2017年 | 9篇 |
2016年 | 16篇 |
2015年 | 20篇 |
2014年 | 11篇 |
2013年 | 20篇 |
2012年 | 14篇 |
2011年 | 37篇 |
2010年 | 3篇 |
2009年 | 5篇 |
2008年 | 19篇 |
2007年 | 14篇 |
2006年 | 14篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
排序方式: 共有322条查询结果,搜索用时 62 毫秒
321.
Primordial gravitational waves (GWs) with frequencies > or approximately equal to 10(-15) Hz contribute to the radiation density of the Universe at the time of decoupling of the cosmic microwave background (CMB). This affects the CMB and matter power spectra in a manner identical to massless neutrinos, unless the initial density perturbation for the GWs is nonadiabatic, as may occur if such GWs are produced during inflation or some post-inflation phase transition. In either case, current observations provide a constraint to the GW amplitude that competes with that from big-bang nucleosynthesis (BBN), although it extends to much lower frequencies (approximately 10(-15) Hz rather than the approximately 10(-10) Hz from BBN): at 95% confidence level, omega(gw)h(2) 相似文献
322.
Johanna Busch Thomas Niemann Jan Neumann Peter Stange Sabrina Gärtner Tristan Youngs Sarah Youngs Dr. Dietmar Paschek Dr. Ralf Ludwig 《Chemphyschem》2023,24(12):e202300031
Defects fundamentally govern the properties of all real materials. Correlating molecular defects to macroscopic quantities remains a challenge, particularly in the liquid phase. Herein, we report the influence of hydrogen bonds (HB) acting as defects in mixtures of non-hydroxyl-functionalized ionic liquids (ILs) with an increasing concentration of hydroxyl-functionalized ILs. We observed two types of HB defects: The conventional HBs between cation and anion (c–a), and the elusive HBs between cations (c–c) despite the repulsive Coulomb forces. We use neutron diffraction with isotopic substitution in combination with molecular dynamics simulations for measuring the geometry, strength, and distribution of mobile OH defects in the IL mixtures. In principle, this procedure allows relating the number and stability of defects to macroscopic properties such as diffusion, viscosity, and conductivity, which are of utmost importance for the performance of electrolytes in batteries and other electrical devices. 相似文献