全文获取类型
收费全文 | 915篇 |
免费 | 14篇 |
专业分类
化学 | 515篇 |
晶体学 | 5篇 |
力学 | 24篇 |
数学 | 22篇 |
物理学 | 363篇 |
出版年
2021年 | 10篇 |
2020年 | 16篇 |
2019年 | 18篇 |
2018年 | 19篇 |
2017年 | 21篇 |
2016年 | 18篇 |
2015年 | 14篇 |
2014年 | 22篇 |
2013年 | 41篇 |
2012年 | 28篇 |
2011年 | 42篇 |
2010年 | 25篇 |
2009年 | 24篇 |
2008年 | 36篇 |
2007年 | 43篇 |
2006年 | 38篇 |
2005年 | 55篇 |
2004年 | 38篇 |
2003年 | 26篇 |
2002年 | 39篇 |
2001年 | 40篇 |
2000年 | 24篇 |
1999年 | 30篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 16篇 |
1988年 | 9篇 |
1987年 | 11篇 |
1986年 | 5篇 |
1984年 | 7篇 |
1983年 | 9篇 |
1981年 | 5篇 |
1979年 | 9篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 8篇 |
1973年 | 11篇 |
1972年 | 5篇 |
1971年 | 11篇 |
1970年 | 9篇 |
1969年 | 5篇 |
1968年 | 4篇 |
1967年 | 7篇 |
1965年 | 5篇 |
排序方式: 共有929条查询结果,搜索用时 15 毫秒
1.
2.
3.
We estimate the possible influence of spectral line profile (Lorentz profile, Van Vleck–Weisskopf profile, and profile obtained by solving kinetic equation) on the rotation part of the dielectric permittivity of water-vapor monomers. Spectral regions corresponding to long-wavelength (static) and high-frequency (optical) limiting cases as well as regions in close proximity to resonances of various intensities are considered. The studied effects are compared with the corresponding effects on water-vapor absorption coefficient, which are related to factors determining the line-shape structure. 相似文献
4.
We describe equipment and a method for performing an experiment on a short meteor radio line of length 85 km. The feature of the experiment is monitoring of meteor-matter deposition to the atmosphere using a radar located at one point of the radio line with the simultaneous determination of the main radio-line characteristics. 相似文献
5.
The molecular structures of phenylphosphine and its analogs, aniline and phenylarsine, were studied by gas-phase electron diffraction and quantum-chemical methods. The geometry and force constants were calculated at the HF/6-31G and B3LYP/6-31G* levels of theory. Phenylphosphine and phenylarsine possess a bisector conformation with asymmetric phenyl rings. The main geometric parameters are as follows (r
a): P-C 1.833(6), C-Cav 1.397(1)Å. The structures of molecules like X2YPh (X = H, F, Cl; Y = N, P, As) were discussed. 相似文献
6.
S Çak?r E Co?kunP Naumov E Biçer? Bulut H ?çbudakO Çak?r 《Journal of Molecular Structure》2002,608(1):101-107
Aspartame adduct of copper(II) chloride Cu(Asp)2Cl2·2H2O (Asp=aspartame) is synthesized and characterized by elemental analysis, FT IR, UV/vis, ESR spectroscopies, TG, DTG, DTA measurements and molecular mechanics calculations. Aqueous solution of the green solid absorbs strongly at 774 and 367 nm. According to the FT IR spectra, the aspartame moiety coordinates to the copper(II) ion via its carboxylate ends, whereas the ammonium terminal groups give rise to hydrogen bonding network with the water, the chloride ions or neighboring carboxylate groups. The results suggest tetragonally distorted octahedral environment of the copper ions. 相似文献
7.
V. M. Gryaznov A. P. Maganyuk A. N. Karavanov V. A. Naumov 《Russian Chemical Bulletin》1984,33(4):853-855
Conclusions When the hydrogenation of dehydrolinalool to linalool is run on a Pd alloy containing 6 wt.% of Ru, which is lean in the -hydrogen phase, the selectivity is much greater than when the amount of the -hydrogen phase is greater. A high selectivity of the hydrogenation is achieved by reducing to a definite limit the amount of hydrogen in the membrane catalyst without using inhibitors of the side reactions, which can contaminate the hydrogenation products.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 926–928, April, 1984. 相似文献
8.
I. A. Litvinov O. N. Kataeva V. A. Naumov F. F. Guseva O. N. Nuretdinova 《Journal of Structural Chemistry》1994,34(5):823-826
A. E. Arbuzov Institute of Organic and Physical Chemistry, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 5, pp. 185–188, September–October, 1993. 相似文献
9.
10.
Thomas S Biswas N Venkateswaran S Kapoor S Naumov S Mukherjee T 《The journal of physical chemistry. A》2005,109(44):9928-9934
The surface-enhanced Raman scattering (SERS) studies of 5-amino tetrazole (5AT), a tetrazole derivative, in aqueous silver sol at pH approximately 9 and on deposited colloidal silver films were carried out and compared with the normal Raman spectrum of the molecule. The experimentally observed Raman bands along with their corresponding infrared bands were assigned based on the results of density functional theory (DFT) calculations. The significant changes evidenced between the SERS and the normal Raman spectra combined with the theoretical data obtained for Ag-5AT system demonstrated that the molecule is adsorbed on colloidal Ag particles through the lone pair of electrons of the nitrogen atom. The contribution of the chemical mechanism for the SERS enhancement was proved by the behavior of the electronic absorption spectrum of the Ag colloid upon addition of 5AT. This is further supported by the theoretical calculations that show that the favorable interaction of the frontier orbitals localized on Ag(+) and the negatively charged nitrogen from the tetrazole ring leads to the formation of the stable (up to 130 kJ mol(-1)) charge-transfer complex. The orientation of the adsorbed species with respect to the metal surface was also predicted by applying the "surface selection rule". In addition, the feasibility of the formation of the polymeric species has also been discussed. 相似文献