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1.
2.
The relation between the elastic shear constants and the dimensional Hume-Rothery factor is traced on the basis of the pseudopotential method for a number of bcc solid solutions AB. It is clarified that in the case of a substantial difference between the atomic volumes A and B, the constant c=(c11-c12)/2 takes on anomalously low values and even vanishes. The conclusion is hence made that the explanation of the 15% Hume-Rothery rule is possible from the aspect of stability of the crystalline lattice to shear. The presence of lattice distortion is not needed here in principle, as had been assumed earlier. It is shown that ordering of atoms according to the CsCl type can result in an abrupt increase in the value of c, i.e., in stabilizing the lattice of the initial disordered solid solution.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 97–102, March, 1980. 相似文献
3.
O. V. Sizova V. I. Baranovskii N. V. Ivanova A. I. Panin 《Journal of Structural Chemistry》1996,37(4):525-536
The electronic spectra of the [Ru(NH3)5pz]2+, [Ru(NH3)5pz]3+, and [Ru(CN)5pz]3− complexes are calculated by the CI INDO method. The effect of solvation on the spectra is considered in a point charge approximation
and in terms of the parametric model of a charged sphere enveloping the metal fragment. Interrelation of these approaches
is discussed. Data on the molecular electrostatic potentials created by the complexes are presented to substantiate the models.
St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 4, pp. 603–618, July–August, 1996.
Translated by I. Izvekova 相似文献
4.
O. V. Sizova A. I. Panin V. I. Baranovskii N. V. Ivanova 《Journal of Structural Chemistry》1996,37(2):181-191
Semiempirical INDO-E/S+RCIP calculations of the electronic structures of the ground and excited states of the pyrazine (pz)
molecule and [Ru(NH3)5pz]q (q=+1, +2, +3) complexes were performed to analyze the dependence of the calculation results on the active MO space and configuration
basis set. Recommendations for the construction of the {Фk} basis sets and formation of the {ϕk} sets are given.
St. Petersburg State University. Translated fromZhurnal Struktumoi Khimii, Vol. 37, No. 2, pp. 206–219, March–April, 1996.
Translated by I. Izvekova 相似文献
5.
The approximation of the liquid model of grain boundaries is used to calculate the bonding energy F of carbon and oxygen interstitial impurities with largeangle grain boundaries in d-transition metals and impurities of d-transition metals in group VIA elements: chromium, molybdenum, and tungsten. It is shown that in the case of interstitial impurities as well as substitutional impurities in d-transition metals the bonding energy is determined by the characteristics of the d-band occupation.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 70–75, April, 1979. 相似文献
6.
Efficient cardiac diffusion tensor MRI by three-dimensional reconstruction of solenoidal tensor fields 总被引:2,自引:0,他引:2
Tensor tomography is being investigated as a technique for reconstruction of in vivo diffusion tensor fields that can potentially be used to reduce the number of magnetic resonance imaging (MRI) measurements. Specifically, assessments are being made of the reconstruction of cardiac diffusion tensor fields from 3D Radon planar projections using a filtered backprojection algorithm in order to specify the helical fiber structure of myocardial tissue. Helmholtz type decomposition is proposed for 3D second order tensor fields. Using this decomposition a Fourier projection theorem is formulated in terms of the solenoidal and irrotational components of the tensor field. From the Fourier projection theorem, two sets of Radon directional measurements, one that reconstructs the solenoidal component and one that reconstructs the irrotational component of the tensor field, are prescribed. Based on these observations filtered backprojection reconstruction formulae are given for the reconstruction of a 3D second order tensor field and its solenoidal and irrotational components from Radon projection measurements. Computer simulations demonstrate the validity of the mathematical formulations and demonstrate that a realistic model of the helical fiber structure of the myocardial tissue specifies a diffusion tensor field for which the first principal vector (the vector associated with the maximum eigenvalue) of the solenoidal component accurately approximates the first principal vector of the diffusion tensor. A priori knowledge of this allows the orientation of the myocardial fiber structure to be specified utilizing one half of the number of MRI measurements of a normal diffusion tensor field study. 相似文献
7.
In the paper, we use the nonlinear multiscale approach of physical mesomechanics to demonstrate that the scales of local crystal structure curvature in solids play a fundamental role in the generation of strain-induced defects and cracks. It is shown that strain-induced defects arise at the interfaces of 2D planar and 3D crystal subsystems by the mechanism of “laser pumping” and cracks nucleate as structural phase decay in the zones of crystal structure curvature where the nonequilibrium thermodynamic potential or so-called Gibbs energy is higher than zero. Nonlinear fracture mechanics eliminates the problem of singularity 1/r in equations of crack growth but requires accounting for local lattice curvature at the crack tip. 相似文献
8.
A configuration interaction (CI) method in restricted CI (RCI) space obtained by imposing inequality-type restrictions on the occupancies of groups of molecular orbitals (MOs) was studied. The direct CI approach in such space was analyzed, and some recommendations concerning practical implementation of the RCI method are given. The corresponding program has been written in FORTRAN 77 for an IBM 486 DX personal computer and has been used for electronic structure calculations on transition metal complexes using a valence MO basis with the INDO approximation. © 1996 by John Wiley & Sons, Inc. 相似文献
9.
A. E. Blinov V. E. Blinov A. E. Bondar A. D. Bukin V. R. Groshev S. G. Klimenko G. M. Kolachev A. P. Onuchin V. S. Panin I. Ya. Protopopov A. G. Shamov V. A. Sidorov Yu. I. Skovpen A. N. Skrinsky V. A. Tayursky V. I. Telnov Yu. A. Tikhonov G. M. Tumaikin A. E. Undrus A. I. Vorobiov V. N. Zhilich 《Zeitschrift fur Physik C Particles and Fields》1992,53(1):33-39
The process γγ→π+π? was measured using the detector MD-1 at VEPP-4. The two-photon reactionse + e ?, μ+ μ? and π+ π? pair production were separated using scintillation counters, Cherenkov counters and shower-range chambers. A radiation widthГ γγ(f 2(1270))=3.1±0.35±0.35 keV was obtained. 相似文献
10.
Technical Physics - The microstructure, phase composition, and parameters of α-Ti-based solid solutions in a Ti–6Al–4V alloy obtained by the 3D printing method without cooling and... 相似文献