全文获取类型
收费全文 | 225篇 |
免费 | 2篇 |
专业分类
化学 | 128篇 |
晶体学 | 4篇 |
力学 | 8篇 |
数学 | 41篇 |
物理学 | 46篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 11篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 11篇 |
2015年 | 5篇 |
2014年 | 11篇 |
2013年 | 21篇 |
2012年 | 18篇 |
2011年 | 18篇 |
2010年 | 13篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 10篇 |
2006年 | 6篇 |
2005年 | 11篇 |
2004年 | 8篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 3篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1971年 | 3篇 |
1965年 | 1篇 |
1957年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有227条查询结果,搜索用时 15 毫秒
21.
Chen G Desinan S Nechache R Rosei R Rosei F Ma D 《Chemical communications (Cambridge, England)》2011,47(22):6308-6310
Core-shell structured Ni@Ru bimetallic nanoparticles are demonstrated as a bifunctional nanoplatform system for the hydrolysis reaction of ammonia-borane and also for magnetic separation. 相似文献
22.
23.
24.
E. Bashandy M. G. Mousa El-Sayad M. Riad El-Aassar 《Zeitschrift für Physik A Hadrons and Nuclei》1965,186(2):108-113
TheK-conversion coefficient of the 321 keVE1 transition in Hf177 has been measured by means of an iron free double focusing beta-ray spectrometer, using the internalexternal conversion method. The result obtained for α K (321)=0.162±0.016 is in disagreement with the theoretical values for pureE1 transition (α K =0.0154) calculated bySliv andBand. The large anomaly observed in theK-conversion process of the inhibitedE1 transition is compatible with a largeM2 admixture or, more probable with the presence of penetration matrix elements. 相似文献
25.
R. Ameziane Hassani A. Bouziani A. Blali 《Rendiconti del Circolo Matematico di Palermo》2004,53(3):337-343
In this paper we define a topologicalG-space, whereG is a monoid, and we extend the notion of bounded sets in this spaces. 相似文献
26.
Low temperature nuclear orientation (LTNO) of neutron deficient85m, 86m+g,87m, 90mY nuclei is described. The magnetic moments are compared with those of neighbouring nuclei. 相似文献
27.
Ekkehard Lindner Gerhard A. Weiss Wolfgang Hiller Riad Fawzi 《Journal of organometallic chemistry》1983,255(2):245-254
The cluster compounds (μ3-S)(μ3-PR)Fe3(CO)9 are obtained by reaction of the dichloroorganylphosphane sulphides RP(S)Cl2 (R = CH3, 4-CH3OC6H4, C6H5) with Na2[Fe(CO)4] in ether under cleavage of the PS bond. On the basis of X-ray crystallographic determinations the iron clusters crystallize for R = 4-CH3OC6H4 and C6H5 in the monoclinic and triclinic space group C2/c and P with Z = 8 and 4, respectively. 相似文献
28.
We investigate a six-dimensional universal extra-dimensional model in the extension of an effective neutrino mass operator. We derive the β -functions and renormalization group equations for the Yukawa couplings, the Higgs self-coupling, and the effective neutrino mass operator in this model. Especially, we focus on the renormalization group running of physical parameters such as the Higgs self-coupling and the leptonic mixing angles. The recent measurements of the Higgs boson mass by the ATLAS and CMS Collaborations at the LHC as well as the current three-flavor global fits of neutrino oscillation data have been taken into account. We set a bound on the six-dimensional model, using the vacuum stability criterion, that allows five Kaluza–Klein modes only, which leads to a strong limit on the cutoff scale. Furthermore, we find that the leptonic mixing angle θ12 shows the most sizeable running, and that the running of the angles θ13 and θ23 are negligible. Finally, it turns out that the findings in this six-dimensional model are comparable with what is achieved in the corresponding five-dimensional model, but the cutoff scale is significantly smaller, which means that it could be detectable in a closer future. 相似文献
29.
Druart G Taboury J Guérineau N Haïdar R Sauer H Kattnig A Primot J 《Optics letters》2008,33(4):366-368
Diffractive axicons are optical components producing achromatic nondiffracting beams. They thus produce a focal line rather than a focal point for classical lenses. This gives the interesting property of a long focal depth. We show that this property can be used to design a simple imaging system with a linear variable zoom by using and translating a diffractive axicon as the only optical component. 相似文献
30.
Ahmed Jasim M. Al-Karawi Ali Jasim Hammood Adil A. Awad Al-Ameen Bariz OmarAli Saba Riad Khudhaier Dhafir T. A. Al- Heetimi 《Liquid crystals》2018,45(11):1603-1619
The following organic and organic–inorganic hybrid compounds were prepared as photo-luminescent materials following efficient and practical synthetic methods: 1,3-bis[4-(n-alkoxy)phenyl]-2-propen-1-one (where, n-alkoxy: O(CH2)nH, n = 6,7,8,9 or 10); 3,5-bis[4-(n-alkoxy)phenyl]-1H-pyrazole (where, n-alkoxy: O(CH2)nH, n = 6,7,8,9 or 10) (in case of n = 7, a mixture of 3,5-bis(4-heptyloxyphenyl)-1H-pyrazole and 3,5-bis(4-heptyloxyphenyl)-4H-pyrazole was detected) and bis(3,5-bis [4-(n-alkoxy) phenyl]-1H-pyrazole) silver(I) nitrate (where, n-alkoxy: O(CH2)nH, n = 6,7,8,9 or 10). The prepared compounds have been characterised and their structures were elucidated depending upon (FTIR, UV-Vis, 1HNMR, 13CNMR, 2D 1H-1H-COSY, 2D 1H-13C-HSQC and mass spectra) in addition to molar conductivity measurements for silver(I) complexes. The mesomorphism behaviour of the prepared compounds was studied using polarised light optical microscopy and confirmed with differential scanning calorimetry and X-ray powder diffraction techniques. The studies showed that among all of these compounds only the pyrazole derivatives are liquid crystal materials. The luminescent properties of all the prepared compounds were also investigated which confirmed that all of these compounds are photo-luminescent in the crystalline solid state and in the mesophase. 相似文献