全文获取类型
收费全文 | 915篇 |
免费 | 14篇 |
专业分类
化学 | 517篇 |
晶体学 | 5篇 |
力学 | 24篇 |
数学 | 22篇 |
物理学 | 361篇 |
出版年
2021年 | 10篇 |
2020年 | 16篇 |
2019年 | 18篇 |
2018年 | 19篇 |
2017年 | 22篇 |
2016年 | 18篇 |
2015年 | 14篇 |
2014年 | 22篇 |
2013年 | 40篇 |
2012年 | 28篇 |
2011年 | 43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 | 38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 31 毫秒
1.
Physics of Atomic Nuclei - The article presents the concept of a channel-type reactor with a combined cooled moderator. The moderator consists of ceramic beryllium oxide and a liquid... 相似文献
2.
3.
N. V. Vysotina A. S. Naumov N. N. Rozanov R. L. Sabirov V. E. Semenov V. A. Smirnov T. V. Starchikova S. V. Fedorov S. A. Chizhov V. E. Yashin 《Optics and Spectroscopy》2004,97(3):411-415
The final stage of self-focusing of 500-ps pulses of a neodymium laser in silicate and phosphate glasses and in the nonlinear liquids perfluorooctane, benzene, and toluene is studied theoretically and experimentally. The formation of spatial solitons, which are stable due to the nonlinearity saturation, is demonstrated. It is found that the intensity of the nonlinearity saturation is close to that of the threshold breakdown for glasses and the role of stimulated Raman scattering is significant for liquids. 相似文献
4.
5.
A computer simulation of the kinetics of free-radical oxidation of lipids in the presence of tocopherol was performed. The induction periods and initial rates of oxidation as functions of initial tocopherol concentrations were found to exhibit extremums. The extended kinetic scheme used in this study describes all types of observed relationships and eliminates illusory contradictions between two groups of experiments in which the antioxidant and prooxidant effects of tocopherol were found. The model can form a basis for the prediction of the effects of tocopherol and its analogs under real conditions. 相似文献
6.
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
7.
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
8.
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
9.
Mironov YV Yarovoi SS Naumov DY Kozlova SG Ikorsky VN Kremer RK Simon A Fedorov VE 《The journal of physical chemistry. B》2005,109(50):23804-23807
The novel vanadium thiobromide, V4S9Br4, with a square-planar metal cluster core was synthesized and characterized by single-crystal X-ray diffraction, measurements of magnetic properties and the heat capacity, and DFT calculations of the electronic structure. At the room temperature, the compound displays paramagnetic properties with an independent spin on each V atom and with a weak exchange constant (J approximately 10 cm(-1)). The paramagnetic state is transformed into a low-spin state (AF-type ordering) at low temperatures. This change is accompanied by a heat-capacity anomaly. The observed magnetic and heat-capacity anomalies can be explained by the thermal excitation of electrons on the closely spaced molecular energy levels in the presence of the Jahn-Teller effect. 相似文献
10.
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