全文获取类型
收费全文 | 650篇 |
免费 | 32篇 |
专业分类
化学 | 425篇 |
晶体学 | 6篇 |
力学 | 22篇 |
数学 | 53篇 |
物理学 | 176篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 13篇 |
2021年 | 11篇 |
2020年 | 15篇 |
2019年 | 19篇 |
2018年 | 16篇 |
2017年 | 12篇 |
2016年 | 24篇 |
2015年 | 21篇 |
2014年 | 28篇 |
2013年 | 50篇 |
2012年 | 51篇 |
2011年 | 52篇 |
2010年 | 22篇 |
2009年 | 31篇 |
2008年 | 32篇 |
2007年 | 28篇 |
2006年 | 16篇 |
2005年 | 29篇 |
2004年 | 28篇 |
2003年 | 23篇 |
2002年 | 23篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1961年 | 2篇 |
排序方式: 共有682条查询结果,搜索用时 15 毫秒
41.
A cellulose derivative/liquid crystal composite‐type electro‐optical cell using a commercial cholesteric liquid crystal (CLC) was investigated. The electro‐optical properties of the system were examined, i.e. the dependence on applied voltage of the reflected wavelength and the minimum and maximum transmissions. A thin film of the CLC was dispersed with a cross‐linked cellulose film of 25 µm thickness. In the voltage dependence of the reflected wavelength it was verified that there is a hysteresis in the reflected wavelength. The variation of the reflected wavelength with temperature was also determined. The results are analysed in the framework of similar systems described in the literature for CLC dispersed in a polymer matrix. 相似文献
42.
Pintu K. Kundu 《Tetrahedron》2010,66(44):8562-8568
The β-aryl-β-silyl and β,β-disilyl propionates have been synthesized from cinnamates and β-silyl acrylates by a regiospecific reductive C-silylation using Mg/silyl chloride/DMF system at room temperature. These reductive C-silylation conditions have also been applied to δ-aryl substituted dienoates wherein silylation took place at the δ-position leading to the synthesis of single regioisomeric allylsilanes with very high stereoselectivity. 相似文献
43.
A study of self-quenching of lyoluminescence yield from gamma-irradiated saccharides and amino acids
Tissue equivalent (TE) lyoluminescence (LL) dosimetry requires practical amount of phosphor for dissolution, typically 5-30 mg. Pronounced mass quenching effect has been observed even in the region of 5 mg, in the cases of LL of lactose-monohydrate, d-glucose, d-mannose, raffinose, sucrose and 1-glutamine. Ordinary concentration-quenching is non-existent but yield per mg falls rapidly with increasing mass of the phosphor. The curves have been fitted with a self-absorption type formula. A well-recognised dose effect is present in quenching curves. The role of free radicals at high radiation doses has been discussed in the contribution of dose effect in quenching. 相似文献
44.
45.
46.
A canonical planar beta-hairpin peptide, stereochemically reengineered into a semicircular bracelet type motif by L-to-D stereochemical inversion in two pairs of its cross-strand neighbor residues, displays protein like ordering including two-state behavior in H2O, which is unusual for a small peptide of this size. 相似文献
47.
S. Kundu 《Ukrainian Mathematical Journal》2013,65(6):945-952
48.
This is a study of the completeness properties of the space C
ps
(X) of continuous real-valued functions on a Tychonoff space X, where the function space has the pseudocompact-open topology. The properties range from complete metrizability to the Baire
space property.
Dedicated to Professor Robert A. McCoy 相似文献
49.
The effect of lattice anharmonicity on the resonant modes of dilute impurities for Au-Cu, Au-Ag and W-Cr metallic systems
are studied from the poles of the double time temperature dependent impure Green’s function of these crystals. The third order
force constants used in the present work are derived assuming the systems to obey the Lennard-Jones potential. The inclusion
of lattice anharmonicity has been found to increase the resonant frequency which depends upon the mass defect, force constant
change parameter and the impurity concentration terms. Some interesting features about the phase shift and the change in width
of the vibrational spectrum are reported at room temperature for the isotopic defects and the defects interacting with host
atoms. The results are found to be in qualitative agreement with the experiments on the systems considered. 相似文献
50.
A simple theoretical analysis is presented for Mössbauer parameters and frequency moments of dilute57Fe impurities in different metallic hosts. These parameters have been evaluated for a general harmonic solid using Green's function method. Our results suggest that the contribution due to force constant change term is significant for the mean square displacement whereas that due to mass disordering term is predominating in the evaluations of mean square velocity. The variation of frequency moments for the impurity with host Debye-temperatures modified by the host to impurity mass ratios are shown for a number of solids. 相似文献