全文获取类型
收费全文 | 992篇 |
免费 | 24篇 |
国内免费 | 3篇 |
专业分类
化学 | 518篇 |
晶体学 | 26篇 |
力学 | 37篇 |
数学 | 93篇 |
物理学 | 345篇 |
出版年
2022年 | 6篇 |
2021年 | 12篇 |
2020年 | 9篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 14篇 |
2016年 | 28篇 |
2015年 | 12篇 |
2014年 | 18篇 |
2013年 | 54篇 |
2012年 | 42篇 |
2011年 | 58篇 |
2010年 | 41篇 |
2009年 | 33篇 |
2008年 | 59篇 |
2007年 | 43篇 |
2006年 | 52篇 |
2005年 | 40篇 |
2004年 | 27篇 |
2003年 | 25篇 |
2002年 | 24篇 |
2001年 | 19篇 |
2000年 | 23篇 |
1999年 | 13篇 |
1998年 | 10篇 |
1997年 | 13篇 |
1996年 | 13篇 |
1995年 | 19篇 |
1994年 | 20篇 |
1993年 | 28篇 |
1992年 | 24篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 14篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1964年 | 5篇 |
1955年 | 5篇 |
排序方式: 共有1019条查询结果,搜索用时 250 毫秒
111.
Structures and electronic properties of clusters of an all-Si analogue of graphene, silicene, have been studied through quantum chemical calculations. The structures of the six-membered rings show interesting chair like puckering, which for large sheet-like clusters form ordered ripples. Binding energies, HOMO-LUMO gaps and polarizabilities for the silicene clusters show interesting monotonic trends analogous to polyacenes. Stacking of two silicene layers leads to the formation of closed 3D clusters with high symmetry and strong Si-Si bonds. The heat of hydrogenation of silicene to form silicanes is overwhelmingly exothermic and leads to the opening up of the HOMO-LUMO gaps. Thus, analogous to graphanes, silicanes are predicted to be interesting materials for hydrogen storage and for their band engineering properties. 相似文献
112.
Umbelliferyl sugars have been used to determine the lectin concentration in very dilute solution by fluorescence quenching methods. The Stern-Volmer plot of fluorescence quenching after considering ground-state complexation is obeyed by several sugars. As little as 1 μg of lectin (in 10 μl) and 250 nM of umbelliferyl sugars can be determined. This method offers a simple, non-destructive and rapid method for the determination of lectin activity. 相似文献
113.
Anasuya Datta C. M. Srivastava N. Venkataramani 《Physica C: Superconductivity and its Applications》1993,210(3-4):408-412
We have examined the DC electrical resistivity of RE-123 superconductors (where RE is a rare earth element) on the basis of a model of correlated electron transfer arising from the electron-phonon interaction. The small polaron stabilization energy (εp) has been obtained from the fitting of the normal state resistivity data. A correlation between the lattice parameters of the unit cell and εp has been observed which is explained on the basis of fermiology. 相似文献
114.
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
115.
Mn2+ doped In2S3–SiO2 nanocomposite thin films were synthesized by sol-gel technique. The films were annealed in air at different temperatures (473–623 K) and characterized by optical, microstructural and electron spin resonance (ESR) study. Optical transmittance study revealed the manifestation of quantum size effect while ESR indicated the presence of manganese in indium sulphide as dispersed dopant rather than manganese cluster. 相似文献
116.
Sambhu N Datta 《Pramana》1993,41(4):345-362
A set of indigenously developed computer programs for ab-initio Hartree-Fock calculations on both closed- and open-shell molecules
have been described. These programs have been written for calculations using GTO basis sets. Integral formulae have been taken
from Taketaet al [8]. Structures and functions of the programs have been discussed. These programs have been extensively tested. Molecular
integrals over GTO basis sets have been chosen for tests and as numerical examples in this paper. Results of calculations
using very accurate minimal bases have been given for methane. Time taken for these computations in a CDC Cyber 180/840 machine
has been indicated. Trends in the calculations have also been illustrated by employing 4-gaussian expansions for the STO’s
and by varying the basis size for LiH and BH+.
An erratum to this article is available at . 相似文献
117.
118.
M. Pal S.K. Pradhan P. Bose A. Datta D. Chakravorty 《Physica E: Low-dimensional Systems and Nanostructures》2006,31(2):224-227
Ni3Al alloys of nanometer dimensions in the range 10–38 nm could be synthesized by reaction sintering of sol–gel-derived Ni/SiO2 nanocomposite and commercially available micrometer-sized aluminum powder. The sintering was carried out at a temperature of 923 K and a pressure of 2.4 MPa. By a suitable choice of sintering conditions a disordered phase of Ni3Al was stabilized. The disordered phase could be converted to an ordered one by an increase of heat treatment temperature. 相似文献
119.
Sambhu N. Datta 《Journal of Chemical Sciences》2007,119(5):351-356
The retarded interaction between an electron and a spin-0 nucleus, that has been derived from electro-dynamical perturbation
theory is discussed here. A brief account of the derivation is given. The retarded form is correct through order v
2/c
2. Use of the relative coordinates leads to an effective one-electron operator that can be used through all orders of perturbation
theory. A few unitary transformations give rise to the interaction that is valid in the non-relativistic limit. 相似文献
120.