全文获取类型
收费全文 | 3821篇 |
免费 | 69篇 |
国内免费 | 4篇 |
专业分类
化学 | 1657篇 |
晶体学 | 42篇 |
力学 | 116篇 |
数学 | 436篇 |
物理学 | 1643篇 |
出版年
2022年 | 30篇 |
2021年 | 83篇 |
2020年 | 74篇 |
2019年 | 86篇 |
2018年 | 131篇 |
2017年 | 102篇 |
2016年 | 148篇 |
2015年 | 86篇 |
2014年 | 113篇 |
2013年 | 178篇 |
2012年 | 162篇 |
2011年 | 163篇 |
2010年 | 162篇 |
2009年 | 132篇 |
2008年 | 192篇 |
2007年 | 170篇 |
2006年 | 152篇 |
2005年 | 155篇 |
2004年 | 111篇 |
2003年 | 115篇 |
2002年 | 99篇 |
2001年 | 99篇 |
2000年 | 88篇 |
1999年 | 50篇 |
1998年 | 49篇 |
1997年 | 50篇 |
1996年 | 44篇 |
1995年 | 23篇 |
1994年 | 28篇 |
1993年 | 39篇 |
1992年 | 39篇 |
1991年 | 44篇 |
1990年 | 33篇 |
1989年 | 39篇 |
1988年 | 33篇 |
1987年 | 28篇 |
1985年 | 29篇 |
1984年 | 31篇 |
1983年 | 27篇 |
1982年 | 26篇 |
1981年 | 27篇 |
1979年 | 34篇 |
1978年 | 31篇 |
1977年 | 42篇 |
1976年 | 34篇 |
1975年 | 28篇 |
1974年 | 29篇 |
1973年 | 34篇 |
1972年 | 29篇 |
1971年 | 28篇 |
排序方式: 共有3894条查询结果,搜索用时 156 毫秒
31.
The electronic structure of single-walled carbon nanotubes was experimentally investigated using x-ray photoelectron spectroscopy, reflection electron energy-loss spectroscopy, and Auger electron spectroscopy. A shake-up satellite structure observed near the C 1s core-level lines in the x-ray photoelectron spectra at high binding energies in the range 284–330 eV due to excitation of π and π + σ plasmons was studied. The effect of irradiation by 1-keV argon ions on the shape of the spectra was analyzed. The shape of the C 1s satellite spectra was found to be sensitive to Ar+ irradiation in the electron energy loss range 10–40 eV corresponding to excitation of π + σ plasmons. Auger spectroscopy revealed the presence of argon on the surface of ion-irradiated samples. The argon content increased to ~4 at. % with increasing irradiation dose. An analysis of the results obtained and their comparison with the data available in the literature led to a qualitative conclusion that the bond angles of the carbon atoms making up the walls of single-walled carbon nanotubes are distorted at sites exposed to Ar+ irradiation. 相似文献
32.
A new theoretical model describing the emission and absorption dynamics in an ensemble of molecules under intense coherent pulsed pumping is developed on the basis of the concepts of cooperative light-induced luminescence (CLIL). The CLIL development is described within the framework of formalism of the system density matrix in the space of photon wave functions. It is shown that the fast growth of CLIL relates to the development of coherent states of the quantum field in the area of efficient cooperative interactions of molecules (coherence volume). A system of equations for the calculation of CLIL energy, population of excited states, and optical absorption of the system in dependence on the laser pump energy density is solved. The theoretical results obtained are in good agreement with the experimental data. 相似文献
33.
The low-temperature reaction of magnesium with fluorobenzene has been investigated. Joint condensation of magnesium and fluorobenzene vapours at low temperatures quantitatively gave phenylmagnesium fluoride in one stage. 相似文献
34.
A. P. Smirnov 《Optics and Spectroscopy》2006,101(2):325-331
Exact formulas for the angular eikonal of decentered and oblique conicoids are obtained based on the analysis of the properties of conicoids and angular eikonals. The case of a paraboloid is considered separately. Exact formulas for the angular eikonal open the possibility of construction of an exact theory of aberrations. 相似文献
35.
Alexander O. Smirnov 《Letters in Mathematical Physics》2006,76(2-3):297-316
We find a new class of Fuchsian equations, with algebro-geometric solutions associated to a hyperelliptic curve. A method for calculating its arithmetic genus and branching points is suggested. Numerous examples are given. 相似文献
36.
37.
Vladimir V. Veremey Yury A. Tuchkin 《International Journal of Infrared and Millimeter Waves》1997,18(4):909-938
An analysis of resonances of scattering from multi-element grating formed by a finite number of resonant elements is presented.
It has been shown that gratings with three and more elements on its period can support the π-mode. The π-mode of a grating
is characterized by the existence of the regions in the vicinity of the grating and along its period where the electromagnetic
field has opposite phases. The existence and excitation of the π-mode in finite gratings with resonant cells formed by several
scatterers having open cavities have been studied. The particular case of the grating with cells formed by three identical
slotted cylinders has been considered in detail. An application of gratings which support the π-mode in electron-vacuum oscillators
of millimeter waves for efficient deceleration of electrons and extracting energy from electron beam is discussed. 相似文献
38.
O. V. Zagorskaya V. V. Smirnov T. N. Rostovshchikova V. L. Kofman 《Journal of Structural Chemistry》1992,33(2):310-313
Moscow State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 2, pp. 170–174, March–April, 1992. 相似文献
39.
L. D. Smirnov S. V. Nikitin A. I. Chernyshev A. A. Sorokin V. P. Lezina V. G. Zabrodnyaya M. M. Kaganskii 《Chemistry of Heterocyclic Compounds》1992,28(12):1425-1431
It has been shown that the alkylation of 2-methyl-9-hydroxy-4H-pyrido[1,2-a]pyrimidin-4-one takes place at the oxygen atom, but electrophilic substitution takes place mainly at position 8 of the molecule (the ortho position relative to the hydroxy group).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1660–1666, December, 1992. 相似文献
40.
A method is proposed for constructing appropriate sets of special points in the Brillouin zone in which the extended unit cell method is used with a subsequent shift from the center of the reduced Brillouin zone. The proposed method offers several advantages over the commonly used Monkhorst-Pack method. The difference in the construction of sets of special points for the direct and reciprocal lattices is discussed for crystals belonging to a nonsymmorphic space group. The cases of a planar square lattice and an fcc lattice are considered to illustrate general results. 相似文献