全文获取类型
收费全文 | 3079篇 |
免费 | 120篇 |
专业分类
化学 | 1649篇 |
晶体学 | 16篇 |
力学 | 59篇 |
数学 | 396篇 |
物理学 | 1079篇 |
出版年
2021年 | 36篇 |
2020年 | 37篇 |
2019年 | 36篇 |
2018年 | 33篇 |
2016年 | 118篇 |
2015年 | 119篇 |
2014年 | 155篇 |
2013年 | 296篇 |
2012年 | 111篇 |
2011年 | 86篇 |
2010年 | 89篇 |
2009年 | 67篇 |
2008年 | 66篇 |
2007年 | 51篇 |
2006年 | 90篇 |
2005年 | 35篇 |
2004年 | 38篇 |
2003年 | 34篇 |
2002年 | 50篇 |
2001年 | 36篇 |
2000年 | 59篇 |
1999年 | 37篇 |
1998年 | 43篇 |
1997年 | 41篇 |
1996年 | 39篇 |
1995年 | 42篇 |
1994年 | 39篇 |
1993年 | 40篇 |
1992年 | 33篇 |
1991年 | 37篇 |
1990年 | 35篇 |
1988年 | 50篇 |
1987年 | 39篇 |
1986年 | 35篇 |
1985年 | 56篇 |
1984年 | 54篇 |
1983年 | 37篇 |
1982年 | 32篇 |
1981年 | 33篇 |
1980年 | 41篇 |
1979年 | 40篇 |
1978年 | 39篇 |
1977年 | 49篇 |
1976年 | 48篇 |
1975年 | 42篇 |
1974年 | 57篇 |
1973年 | 37篇 |
1972年 | 29篇 |
1969年 | 28篇 |
1962年 | 27篇 |
排序方式: 共有3199条查询结果,搜索用时 15 毫秒
91.
V. Ščasnár M. Zemánek L. Šoltés M. Lukácsová 《Journal of Radioanalytical and Nuclear Chemistry》1989,134(2):433-436
An HPLC method was developed for studying the stability of [3H] stobadin stored in physiological saline or buffers at various pH. Optimum conditions for the separation of degradation products were elaborated. A high-performance liquid chromatograph equipped with a radioactivity detector was used. 相似文献
92.
Magnetics structures of powdered orthorhombic R(Cu, Ni)2 compounds (R = heavy rare earth) determined by neutron diffraction are described. The influence of magnetocrystalline anisotropy and exchange interactions on the type of magnetic ordering is discussed.Dedicated to Academician Vladimír Hajko on the occasion of his 65th brithday.We would like to express our thanks to Professor P. Luká for continual interest and encouragement and to . Zajac and V. Sechovský for many fruitfull discussions. 相似文献
93.
P. Kratochvíl B. Smola I. Stulíková P. Vostrý F. Jandoš J. Šedivec 《Czechoslovak Journal of Physics》1985,35(3):257-260
Static softening of AISI 321 steel after cold and hot deformation characterizing the industrial thermomechanical treatment was studied by means of tensile tests and TEM. The deformation temperature, the strain and the grain size were the main parameters determining the final softening. The results can be applied for optimization of the solution annealing. 相似文献
94.
In the present paper we report the first experimental results on ac and dc conductivity and permittivity of adenine hemisulphate hydrate and adenine sulphate measured at atmospheric and high hydrostatic pressures. For both materials ac conductivity is of
s type, where:s 1·1· Room temperature dc conductivity of adenine hemisulphate hydrate equals approximately 5×10–15
–1 cm–1 with an activation energy of 0·86 eV; dc conductivity of adenine sulphate is less than 10–16 cm–1. On the basis of these measurements and those carried out at high pressure, it is concluded that conductivity of adenine hemisulphate hydrate is of electronic type.The authors wish to thank Dr. J. Zachová for the preparation of adenine salts single crystals. 相似文献
95.
We calculate the density of states for the nondegenerate Anderson model for various values ofu=U/ andn
f
using the perturbation theory withu as the expansion parameter. Summing all the -independent self-energy diagrams, we use the Friedel sum rule and Ward identities to express the physical quantities in terms of the remaining -dependent part of the self-energy, which we evaluate to the 2nd order. The results for the spin and charge susceptibilities obtained in such a way compare rather well with the Bethe-ansatz results. The density of states exhibits different features in different parts of the parameter space. In Kondo region (u>1,n
f
1, i.e., –
f
~U/2), we obtain a many-body resonance (half-width T
K
) around the Fermi level and two broad peaks () at about
f
+n
f
U and
f
+U. In the VF region (u>1, and |
f
|) we obtain only two peaks (), one at about
f
and one between
f
+n
f
U and
f
+U. The consequences regarding the shape of the photoemission and inverse photoemission spectra of Ce intermetallics are discussed. 相似文献
96.
Zusammenfassung Eine Reihe von Metallkomplexen des 2,5-Dibenzoyl-3,4-dihydroxy-selenophens wurden spektroskopisch untersucht. Das Verhalten des Wismutkomplexes und die Möglichkeiten einer spektrophotometrischen Wismutbestimmung auf diesem Wege wurden eingehend studiert.
Herrn Univ.-Prof. Dr.Hans Lieb zum 80. Geburtstag gewidmet. 相似文献
Summary A spectroscopic examination was made of a series of metal complexes of 2,5-dibenzoyl-3,4-dihydroxyselenophen. The behavior of the bismuth complex and the possibilities of a spectrophotometric method of determining bismuth in this manner were studied thoroughly.
Herrn Univ.-Prof. Dr.Hans Lieb zum 80. Geburtstag gewidmet. 相似文献
97.
JPC – Journal of Planar Chromatography – Modern TLC - Flavonoids and phenolic acids with a variety of biological activity are considered to be the main compounds in propolis–a... 相似文献
98.
J. Šňupárek L. Mrkvičková O. Quadrat Z. Walterová P. Bradna 《Colloid and polymer science》2000,278(12):1205-1210
Model ethyl acrylate–methacrylic acid copolymer latices and latices of particles cross-linked by copolymerizing small amounts
of water-soluble N,N′-methylenebisacrylamide were prepared by nonseeded semicontinuous emulsion copolymerization. Dynamic and static light scattering
measurements indicated a slightly higher degree of polydispersity in the case of cross-linked particles, especially in the
initial stages of polymerization. The hydrodynamic volume of the alkalinized particles controlling the viscosity properties
of the dispersions decreased with the time of polymerization and in the case of cross-linked copolymer almost reached a constant
value at about 1 h. The different character of the particle structure was confirmed by differences in particle disintegration
after alkali addition or in the presence of methanol.
Received: 2 February 1999/Accepted: 28 June 2000 相似文献
99.
Summary Gas chromatographic unified retention indices for 43 hydrocarbons (alkanes and cycloalkanes) are given for squalane and OV-101. Comparison of these values and unified retention index increments are presented as linear regression equations with high correlation coefficients and acceptable standard deviations. 相似文献
100.
A simple and rapid radiochemical method for the efficient and selective isolation of3H-stobadine from plasma, urine and organ homogenates has been developed. The method comprises the extraction of3H-stobadine from the biological matrix containing 2M Na2CO3 into n-hexane followed by scrubbing of partly coextracted metabolites into an equal volume of 2M Na2CO3. The specificity of the procedure presented is demonstrated by TLC and the comparison of distribution coefficients of authentic and apparent (isolated) substances. 相似文献