首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   306篇
  免费   0篇
化学   197篇
晶体学   1篇
力学   28篇
数学   24篇
物理学   56篇
  2021年   3篇
  2019年   4篇
  2018年   5篇
  2017年   11篇
  2016年   10篇
  2015年   2篇
  2014年   6篇
  2013年   8篇
  2012年   20篇
  2011年   10篇
  2010年   12篇
  2009年   7篇
  2008年   12篇
  2007年   7篇
  2006年   7篇
  2005年   6篇
  2004年   10篇
  2003年   10篇
  2002年   6篇
  2001年   9篇
  2000年   6篇
  1999年   8篇
  1998年   7篇
  1997年   4篇
  1996年   4篇
  1995年   6篇
  1994年   6篇
  1993年   4篇
  1991年   5篇
  1990年   2篇
  1989年   4篇
  1987年   6篇
  1986年   3篇
  1984年   2篇
  1983年   4篇
  1982年   2篇
  1981年   3篇
  1979年   2篇
  1978年   3篇
  1977年   3篇
  1975年   2篇
  1974年   5篇
  1973年   6篇
  1972年   5篇
  1971年   10篇
  1970年   6篇
  1969年   6篇
  1968年   7篇
  1967年   3篇
  1965年   1篇
排序方式: 共有306条查询结果,搜索用时 15 毫秒
221.
The technique of quadratic and cubic summation of power series in the perturbation method was first used for finding exact solutions to nonlinear evolution equations. The series were construction with the use of exponential partial solutions to linearized equations. The solution of both classic and modified nonintegrable Korteweg-de Vries equations, the modified Burgers equation, and the Fisher one allows one to demonstrate specific features of the mentioned method. We obtain exact solitary wave solutions to the mentioned equations in the form of a wave impulse and a wave front and show that summation parameters depend on the pole orders of the desired solutions.  相似文献   
222.
223.
A quasi-hyperbolic equation is derived that simulates the axisymmetric propagation of bending waves in a cylindrical shell, which interacts with a nonlinearly elastic medium. With the correct asymptotic procedure, the study of a wave process reduces to analysis of a nonlinear Schrödinger equation. It is established that the development of modulation instability requires a “soft” nonlinearity of the medium surrounding the shell. Operating modes that allow the propagation of stable light envelope solitons are revealed.  相似文献   
224.
Emission of dimers from the substrate to the vapor medium during silver vapor deposition onto an ideal substrate is calculated. Dimers are demonstrated to form on the substrate owing to random collisions of atoms during their surface migration, and emission of dimers is caused by thermal fluctuations of the crystal lattice of the substrate. Calculations based on Langmuir’s modified model of sorption show that emission mainly occurs at the stage of filling of the first atomic layer on the substrate and in regimes of “condensation failure” when intense condensation does not occur even at high levels of supersaturation and nucleation frequency because of the low energy of bonding of vapor atoms with the substrate. A relation of emission of dimers to the intensity of condensation and condensate microroughness on the substrate is found.  相似文献   
225.
New dinuclear copper(I) complexes with bridging bis-diimine ligands were synthesized on the basis of benzimidazole derivatives. The obtained complexes showed photo- and electroluminescent properties. Copper-containing emitters exhibited yellow, orange, and yellow–green electroluminescence with a maximum brightness of 1166 cd/m2.  相似文献   
226.
Naphthaleneytterbium, C10H8Yb(THF)3, reacts with Cp2Cr, Cp2Co, Cp2Ni, and Cp2V in THF to give Cp2Yb. In the case of the reaction of C10H8Yb(THF)3 with Cp2V, vanadium-containing intermediates could be isolated. One of them, CpVC10H8VCp, has been characterized by X-ray diffraction. The crystals are monoclinic, space group P21/n, with a 907.0(5), b 798.8(3), c 1080.8(5) pm, β 105.21(4)°; Z = 2. The structure was refined to R = 0.0288 for 1131 observed reflections (Fo > 4σ(Fo)).  相似文献   
227.
The new ruthenium(II) complex Ru(PMIP)2(PPh3)2 (HPMIP is 4-isobutyryl-3-methyl-1-phe-nylpyrazol-5-one) was obtained from RuCl2(PPh3)3 and Na(PMIP)(DME) (DME is dimethoxyethane). The structures of the complex obtained and the starting sodium pyrazolonate were determined by X-ray diffraction. The ruthenium pyrazolonate complex initiates metathetical norbornene polymerization producing high-molecular-weight polynorbornene in low yield.  相似文献   
228.
Results of investigations into the spectral and power characteristics of two-photon fluorescence of a liquid drop with the Rhodamine 6G dye irradiated by femtosecond laser pulses are presented. It is demonstrated that stimulated emission of two types is realized in drops with the concentrated dye solution, namely, superfluorescence within the drop volume and lasing on whispering gallery modes.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 15–19, April, 2005.  相似文献   
229.
In this paper, we address the stability of an elastic thin annular plate stretched by two point loads that are located on the outer boundary. A roller support is considered on the outer boundary while the inner edge of the plate is free. Muskhelishvili’s theory of complex potentials has been applied to obtain a solution of the plane problem in the form of a power series. The buckling problem has been solved using the Rayleigh–Ritz method, based on the energy criterion. The critical Euler force and the respective buckling mode have been computed. Dependence between the critical force and the relative orifice size has been illustrated. Analysis of the results has shown that a symmetric buckling mode takes place for a sufficiently large hole, with the greatest deflection observed around the hole along the force line. However, an antisymmetric buckling mode occurs for relatively small holes, with the greatest deflection being along a line that is orthogonal to the force line.  相似文献   
230.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号