全文获取类型
收费全文 | 201篇 |
免费 | 0篇 |
专业分类
化学 | 52篇 |
晶体学 | 2篇 |
力学 | 8篇 |
数学 | 28篇 |
物理学 | 111篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 9篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 10篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 9篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 9篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1993年 | 2篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1963年 | 3篇 |
排序方式: 共有201条查询结果,搜索用时 31 毫秒
41.
Doklady Mathematics - The asymptotic behavior of the chromatic number of the binomial random hypergraph $$H(n,k,p)$$ is studied in the case when $$k \geqslant 4$$ is fixed, n tends to infinity, and... 相似文献
42.
43.
V. G. Arkhipkin V. A. Gunyakov S. A. Myslivets V. P. Gerasimov V. Ya. Zyryanov S. Ya. Vetrov V. F. Shabanov 《Journal of Experimental and Theoretical Physics》2008,106(2):388-398
Transmission spectra of a one-dimensional photonic crystal (PC) formed by two multilayer dielectric mirrors and a planar oriented layer of 5CB nematic liquid crystal (LC) that is sandwiched between these mirrors and serves as a structure defect are investigated experimentally. Specific features of the behavior of the spectrum of defect modes as a function of the angle of incidence of light on the crystal are studied for two polarizations: parallel and perpendicular to the director of the LC; the director either lies in the plane of incidence or is perpendicular to it. It is shown that, for the configurations considered, the maxima of the defect modes shift toward the short-wavelength region as the tilt angle of incidence radiation increases; this tendency is more manifest for the parallel-polarized component, when the director lies in the plane of incidence. In the latter case, the width of the photonic band gap (PBG) appreciably decreases. The temperature dependence of the polarization components of the transmission spectra of a PC is investigated in the case of normal incidence of light. The spectral shift of defect modes due to the variation of the refractive index of the LC at the nematic-isotropic liquid phase transition point is measured. It is shown that, in real PCs, the amplitude of defect modes decreases when approaching the center of the band gap, as well as when the number of layers in the dielectric mirrors increases. Theoretical transmission spectra of the PCs calculated by the method of recurrence relations with regard to the decay of defect modes are in good agreement with experimental data. 相似文献
44.
45.
Doklady Physics - The frequency and concentration dependences of the effective complex permittivity of a composite consisting of silver nanoparticles in a polystyrene dielectric matrix have been... 相似文献
46.
E. E. Netreba S. V. Shabanov A. A. Velikozhon N. V. Somov 《Russian Journal of Inorganic Chemistry》2016,61(11):1414-1418
The centrosymmetric binuclear manganese(II) nitrate complex with a bicyclic bis-carbamide, namely, 2,4,6,8-tetramethyl-2,4,6,8-tetraazabicyclo(3.3.0)octane-3,7-dione, or mebicar (Mk) [Mn(C8H14N4O2)(H2O)(NO3)2]2 · H2O (I), has been synthesized for the first time. The structure of complex I has been solved (CCDC no. 1435139). Crystals of complex I are monoclinic, space group P21/c, a = 12.8108(11) Å, b = 10.0662(2) Å, c = 18.6367(17) Å, β = 136.512(16)°, V = 1654.0(4) Å3, ρcalcd = 1.659 g/cm3, Z = 2. Each manganese atom is coordinated to the two oxygen atoms of two Mk molecules related by the symmetry codes (1–x, 2–y, 1–z) and to two bidentate nitrate anions and one water molecule. The coordination polyhedron of the manganese atom is a strongly distorted pentagonal bipyramid. The Mn···Mn distance in the complex is 8.7261(9) Å. 相似文献
47.
B. A. Belyaev N. A. Drokin V. F. Shabanov V. N. Shepov 《Physics of the Solid State》2000,42(3):577-579
Parallel and perpendicular components of the dielectric constant for 5CB nematic liquid crystal are measured in a relaxation region. Two frequencies f 1≈30 and f 2≈350 MHz are determined at which the inversion of the dielectric anisotropy sign is observed. It is shown that the observed sizable high-frequency shift of f 2 with respect to the value calculated according the Debye theory is caused by the dielectric resonance near the relaxation region. 相似文献
48.
Polarization studies of low-frequency Raman spectra of solid solutions of p-dichlorobenzene with p-bromchlorobenzene (50% p-dichlorobenzene) were carried out. Analysis of the lattice vibration spectra of these mixed crystals shows that vacancies can be present in their structure. The presence of vacancies is responsible for the emergence of additional lines, including those in the 70 cm?1 region. The calculation of the diffusion activation energy in a mixed crystal proves that its magnitude is determined by the spatial arrangement of p-bromchlorobenzene molecules in the lattice, their orientation relative to parahalides, and (to a lesser extent) temperature variations. 相似文献
49.
D. V. Shabanov 《Radiophysics and Quantum Electronics》2000,43(4):317-323
We consider fluctuations of the radiation of a low-coherence source transmitted through a two-arm interferometer and transformed
by a square-law detector. It is assumed that the output radiation of the source is a stationary Gaussian narrow-band random
process. The fluctuation process at the detector output is presented as the sum of the intensity noise and the interference-component
noise. We calculate the relationships between the spectral densities of these components and the degree of their correlation
for different delays between the interferometer arms. We show theoretically and confirm experimentally that the power of interference-component
fluctuations is nonzero even if the delay between the interferometer arms exceeds the correlation time of the process at the
source output.
Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh
Uchebnykh Zavedenii, Radiofizika, Vol. 43, No. 4, pp. 350–356, September., 2000 相似文献
50.
A. L. Shabanov N. M. Seidov U. A. Gasanova Z. O. Kakhramanova M. M. Gasanova 《Russian Journal of Organic Chemistry》2009,45(1):26-29
Metalation of toluene and isopropylbenzene with alkali metal-crown ether complexes led to the corresponding α-metalated alkylbenzenes. Treatment of the latter in succession with solid carbon dioxide, water, and hydrochloric acid gave carboxylic or dicarboxylic acids in 65–78% yield. Metalation of isopropylbenzene with sodium or potassium crown ether complexes above 90°C was accompanied by cleavage of the polyether ring with formation of organometallic compounds which then reacted with isopropylbenzene to produce 2-sodio(potassio)-2-phenylpropane and open-chain oligoether. 相似文献