全文获取类型
收费全文 | 65篇 |
免费 | 9篇 |
国内免费 | 9篇 |
专业分类
化学 | 23篇 |
晶体学 | 2篇 |
力学 | 2篇 |
数学 | 13篇 |
物理学 | 43篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 4篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 6篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有83条查询结果,搜索用时 8 毫秒
41.
中国的百岁老人研究Ⅴ.微量元素——长寿的重要物质基础 总被引:3,自引:0,他引:3
秦俊法 《广东微量元素科学》2008,15(2):15-32
对中国长寿地区和百岁老人进行了流行病学调查及实验研究。结果表明,微量元素在长寿形成的过程中起着极为重要的作用。我国长寿地区的饮用水中,含有丰富的、以含水络合离子形式存在的生命动力元素群;在自然环境中和人体内部存在一个优越的微量元素谱。这些微量元素有调节体内脂质代谢、降低自氧化损伤、延长生存寿命的作用,它们是百岁老人得以健康长寿的最重要的物质基础之一。 相似文献
42.
我们最近证明,利用红外和深紫外双色激光场,SF6分子的结构信息可以通过其电离谱上的相干条纹获得[arXiv,1912.08499(2019)].在本文中,我们利用该方法考察了两种不同几何结构的分子离子H32+ 在激光场中的直接阈上电离(ATI)过程.通过与单色激光场中电离谱的比较发现,双色激光场的电离谱可以分辨分子的不同几何结构.由相干条件导出的公式可以很好地解释直接ATI动能谱和动量谱中的干涉条纹.此外,还发现通过改变分子核间距或改变激光强度可以改变电离谱的形状.由此可以推断,双色激光场诱导的ATI谱具有鉴别分子不同构型的能力,对复杂分子的几何结构成像具有一定的参考意义. 相似文献
43.
The storage of long bunches for large time intervals needs flattened stationary buckets with a large bucket height.Collective effects from the space charge and resistive impedance are studied by looking at the incoherent particle motion for the matched and mismatched bunches.Increasing the RF amplitude with particle number provides r.m.s wise matching for modest intensities.The incoherent motion of large amplitude particles depends on the details of the RF system.The resulting debunching process is a combination of the too small full RF acceptance together with the mismatch,enhanced by the collective effects.Irregular single particle motion is not associated with the coherent dipole instability.For the stationary phase space distribution of the Hofmann-Pedersen approach and for the dual harmonic RF system,stability limits are presented,which are too low if using realistic input distributions.For single and dual harmonic RF system with d=0.31,the tracking results are shown for intensities,by a factor of 3 above the threshold values.Small resistive impedances lead to coherent oscillations around the equilibrium phase value,as energy loss by resistive impedance is compensated by the energy gain of the RF system. 相似文献
44.
V. Lensky V. Baru J. Haidenbauer C. Hanhart A. E. Kudryavtsev U. -G. Meißner 《The European Physical Journal A - Hadrons and Nuclei》2006,27(1):37-45
We study the production amplitude for the reaction NN → NNπ up to next-to-leading order in chiral perturbation theory using a counting scheme that takes into account the large scale
introduced by the initial momentum. In particular, we investigate a subtlety that arises once the leading loop contributions
are convoluted with the NN wave functions as demanded by the non-perturbative nature of the NN interaction. We show how to properly identify the irreducible contribution of loop diagrams in such type of reaction. The
net effect of the inclusion of all next-to-leading-order loops is to enhance the leading rescattering amplitude by a factor
of 4/3, bringing its contribution to the cross-section for pp → dπ+ close to the experimental value. 相似文献
45.
46.
Khalil Faghihi 《高分子科学》2004,22(4)
Facile and rapid polycondensation reactions of N,N′-(pyromellitoyl)-bis-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h were developed by using a domestic microwave oven in the presence ora small amount of polar organic medium such as o-cresol. The polycondensation reactions proceeded rapidly, compared with the conventional solution polycondensation, and was completed within 7-10 min, producing a series of novel optically active poly(amide-imide)s 3a-h with high yield and inherent viscosity of 0.35-0.65 dL/g. All of the above polymers were fully characterized by FT-IR, elemental analyses, inherent viscosity (ηiaa), solubility test and specific rotation. Some structural characterization and physical properties of these optically active poly(amide-imide)s are reported. 相似文献
47.
Frame multiresolution analysis and infinite trees in Banach spaces on locally compact abelian groups
S.S.Panday 《分析论及其应用》2004,20(3):231-241
We extend the concept of frame multiresolution analysis to a locally compact abelian group and use it to define certain weighted Banach spaces and the spaces of their antifunctionals. We define analysis and synthesis operators on these spaces and establish the continuity of their composition. Also, we prove a general result to characterize infinite trees in the above Banach spaces of antifunctionals. This paper paves the way for the study of corresponding problems associated with some other types of Banach spaceson locally compact abelian groups including modulation spaces. 相似文献
48.
采用基于Guo,Aberg和Crasemann发展的强激光场中的非微扰量子散射理论(GAC理论),研究了线偏振双色激光场中氪(Kr)原子阈上电离的光电子角分布,双色激光场由一系列相同的单周期激光脉冲组成.研究发现光电子角分布有强烈的位相依赖关系,且呈现出反演不对称性、喷射结构和展宽结构等现象,这为实验上通过改变双色激光场的相对相位来观察和控制光电子角分布提供了一种有效的方法. 相似文献
49.
50.
The sensitivity of Doppler wind lidar is an important parameter which affects the performance of Doppler wind lidar. Aerosol scattering ratio, atmospheric temperature, and wind speed obviously affect the mea- surement of Doppler wind lidar with iodine filter. We discuss about the relationship between the measurement sensitivity and the above atmospheric parameters. The numerical relationship between them is given through the theoretical simulation and calculation. 相似文献