全文获取类型
收费全文 | 321篇 |
免费 | 6篇 |
专业分类
化学 | 131篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 167篇 |
物理学 | 26篇 |
出版年
2024年 | 2篇 |
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 5篇 |
2017年 | 5篇 |
2016年 | 14篇 |
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 22篇 |
2012年 | 14篇 |
2011年 | 10篇 |
2010年 | 15篇 |
2009年 | 12篇 |
2008年 | 17篇 |
2007年 | 24篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1976年 | 9篇 |
1975年 | 2篇 |
1974年 | 8篇 |
1960年 | 1篇 |
排序方式: 共有327条查询结果,搜索用时 15 毫秒
101.
Feierabend KJ Havey DK Vaida V 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(12):2775-2781
Spectra of gas phase HNO3 were collected in the region 2000-8500 cm(-1) using Fourier-transform infrared spectroscopy. This region is dominated by the nu1 O-H stretching mode but also contains many previously unreported combination bands and overtones. This work marks the first observation of Fermi resonance the 2nu1 O-H stretching overtone. Previously unobserved bands were assigned and integrated intensities were obtained. For bands already reported in the literature, comparisons of relative intensities are presented when possible. This work gives a brief discussion on the trends in overtone intensities and on mode mixing in HNO3 in relation to previous experimental and theoretical studies. 相似文献
102.
This paper is a continuation of [1]. 相似文献
103.
E. Mazėtis 《Lithuanian Mathematical Journal》2000,40(3):248-257
In the paper, with the use of the E. Cartan exterior forms method, the theory of linear and affine connections of the generalized
Kawaguchi space of order two is constructed. It is proved that the linear connection of this space incorporates intrinsic
antiquaternional structures, the conditions of their complete integrability are found, and the affine connections associated
with the above-mentioned structures are constructed.
Translated from Lietuvos Matematikos Rinkinys, Vol. 40, No. 3, pp. 321–334, July–September, 2000.
Translated by R. Lapinskas 相似文献
104.
105.
106.
107.
108.
Mifodijus Sapagovas Regimantas Čiupaila Živilė Jokšiene 《Lithuanian Mathematical Journal》2014,54(3):345-355
We consider conditions for the existence of the eigenvalue λ = 0 in the eigenvalue problem for a differential operator with a variable coefficient and integral conditions. We analyze how these conditions depend on such properties of the coefficient p(x) as monotonicity and symmetry and observe some other properties of the spectrum of the eigenvalue problem. Particularly, we show by a numerical experiment that the fundamental theorem on the increase of the eigenvalues in the case of increasing coefficient p(x) is not valid for the eigenvalue problem with nonlocal conditions. 相似文献
109.
Laurynas Staišiūnas Konstantinas Leinartas Meilutė Samulevičienė Povilas Miečinskas Asta Grigucevičienė Remigijus Juškėnas Eimutis Juzeliūnas 《Journal of Solid State Electrochemistry》2013,17(6):1649-1656
Nanocrystalline Mg–Nb and Mg–Nb–Al–Zn alloy films were deposited by dc magnetron sputtering on glass and quartz substrates in a wide range of niobium concentrations from 6 to 80 at.%. Structural, electrochemical and corrosion properties of the films were studied by X-ray diffraction, dc voltammetry, electrochemical impedance spectroscopy and electrochemical quartz crystal microbalance. Development of body-centred cubic Nb structure in the Mg–Nb alloy matrix yielded the effects of lattice contraction, grain refining and electrochemical passivity. The measurements showed high corrosion resistance of the films in alkaline solutions when niobium content was one third or more. An increased corrosion resistance was achieved by introducing minor amounts of Al (ca. 2 at.%). In particular, such Al effect was pronounced at lower Nb concentrations (20 to 30 at.%). Semiconductor properties of spontaneously formed oxide on Mg–Nb alloy were studied by Mott–Schottky plots, which indicated highly doped n-type oxide structures on Mg–Nb surface. The paper fills some gap in understanding of niobium–magnesium systems, which show potential for applications in hydrogen storage, switchable mirrors and corrosion protection. 相似文献
110.
AbstractPhyllanthus phillyreifolius (Euphorbiaceae), poorly studied plant species, was fractionated using conventional and high pressure extraction techniques such as supercritical fluid and pressurized liquid extractions. Lipophilic substances were extracted with n-hexane and supercritical CO2 with or without co-solvent ethanol, meanwhile higher polarity fractions were recovered with acetone and 70% ethanol. Antioxidant potential was assessed by various chemical assays, which revealed that 70% ethanol was the most effective solvent for recovery of antioxidants. UPLC-MS phytochemical analysis of hydrophilic extracts confirmed geraniin as the main constituent of P. phillyreifolius. Other quantitatively important compounds were phyllanthusiin D and elaeocarpusin. Three isomers of tocopherol (α, β and γ) were quantified by HPLC in lipofhilic extracts. Generally, the results from this study revealed high antioxidant potential of P. phillyreifolius; consequently the plant may be considered as a promising source of antioxidants for functional foods, nutraceuticals and pharmaceutical formulations. 相似文献