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81.
Kudich AV Bataev VA Abramenkov AV Godunov IA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2004,60(8-9):1995-2003
The structure of the conformationally flexible acetyl fluoride molecule (CH3CFO and CD3CFO) in the ground (S0) and lowest excited triplet (T1) and singlet (S1) electronic states was calculated by different quantum-chemical methods (RHF, UHF, MP2, CASSCF). The equilibrium geometric parameters and harmonic vibrational frequencies of the molecules in these electronic states were estimated. The calculations demonstrated that the electronic excitation causes considerable conformational changes involving the rotation of the CH3(CD3) top and a substantial deviation of the CCFO carbonyl fragment from planarity. For large-amplitude vibrations, namely, for the torsional vibration in the S0 state and the torsional and inversion (nonplanar carbonyl fragment) vibrations in the T1 and S1 states, the quantum-mechanical problems were solved in one-dimensional (1D) and two-dimensional (2D) approximations. The results of calculations are in good agreement with experimental data. 相似文献
82.
The potential energy surfaces of the nitroso compounds CClF2NO and CCl2FNO in the ground and lowest excited singlet and triplet electronic states were studied by various ab initio methods (including multiconfigurational methods). The equilibrium geometric parameters, vibrational frequencies, internal rotation potential functions, and rotational contours of bands in the S1 S0 vibronic spectrum of the CClF2NO molecule were calculated. For the molecules under consideration, the quantum-mechanical problem on torsional motion was solved. The results of calculations are, on the whole, in good agreement with experiment. 相似文献
83.
84.
S. K. Godunov 《Siberian Mathematical Journal》1992,33(6):939-949
Novosibirsk. Translated fromSibirski Matematicheski Zhurnal, Vol. 33, No. 6, pp. 3–13, November–December, 1992. 相似文献
85.
S. K. Godunov V. V. Denisenko N. S. Kozin N. K. Kuz'mina 《Journal of Applied Mechanics and Technical Physics》1975,16(5):811-814
The work applies the relaxation viscoelastic model proposed in [1–3] for calculations of high-rate deformation of bars and plates and for refining the interpolation equations of Maxwellian viscosity χ (a magnitude inverse to the relaxation time τ of the tangential stresses) by means of them. These calculations were carried out to study the dependence of the dynamic yield limit σg on the deformation rate ?·. The authors propose that the dependence σg(?, T) in ?· be transformed, such that χ = ?· (σ, T) (here σ is the intensity of the tangential stresses and T is temperature) in order to construct interpolation equations for Maxwellian viscosity χ. A numerical analysis demonstrated that this equation leads to the correct qualitative dependence in calculations of σg (?·). A correction factor is introduced into the equation χ = χ(σ, T) in order for the numerical calculations to quantitatively coincide with the experimental data in this work. 相似文献
86.
Vapor-state absorption spectra have been recorded for acetyl fluoride and acetyl chloride and also for deuterated derivatives with path lengths up to 40 m. The origins of the S1S0 transitions have been derived, together with the torsional-vibration energy levels in the ground state S0 and excited singlet state S1. Fitting the calculated and observed rotational contours of the vibronic bands has been used to estimate the geometrical parameters in the S1 states. The carbonyl groups in the S1 states are nonplanar. The internal-rotation potentials have been determined for acetyl fluoride and acetyl chloride in the S1 and S0 states. The relative intensities of the torsional transitions in those states indicate that the minima in the potential energy are appreciably displaced along the torsional coordinate in the S0 and S1 states.Chemical Faculty, Lomonosov Moscow University. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 1, pp. 26–30, January–February, 1993. 相似文献
87.
We present a theoretical investigation of oxalyl fluoride (COF)2 in the ground and the four lowest excited (two singlet and two triplet) electronic states of the n,π∗-type mainly with the CASPT2(8-6)/cc-pVTZ method. Geometries, vibrational frequencies, potential energy functions of internal rotation, and adiabatic electronic transition energies were obtained. The conformer energy difference and the barrier to internal rotation in the ground electronic state were extrapolated to the complete basis set limit. The planar trans and cis conformations were the most stable configurations for all five electronic states under study. We found that the allowed electronic transition of the cis conformer has a transition energy that is significantly higher than that predicted in previous studies. For the excited states, the internal rotation was found to be accompanied by significant non-planar distortion of both carbonyl fragments, indicating strong coupling between these molecular motions. 相似文献
88.
Ab initio quantum-chemical calculations of equilibrium geometric parameters, vibrational frequencies, and potentials of internal rotation
for CCIF2NO and CCl2FNO molecules in the ground (S0) and lowest excited singlet (S1) electronic states were performed. The results of calculations were compared with experimental data. A new interpretation
of experimental spectra of the CCIF2NO molecule was suggested.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1453–1458, August, 1999. 相似文献
89.
We calculate the Clebsch–Gordan coefficients for orthogonal rather than unitary representations of the rotation group. 相似文献
90.
S. K. Godunov A. F. Demchuk N. S. Kozin V. I. Mali 《Journal of Applied Mechanics and Technical Physics》1974,15(4):526-529
The purpose of this study is the construction of interpolation formulas for the dependence of Maxwell viscosity, a quantity which is the reciprocal of shear-strain relaxation time , on shear-strain intensity and temperature for several metals: iron, aluminum, copper, and lead. This function was interpolated in various temperature and deformation velocity ranges in accordance with available experimental data for iron (0 107 sec–1, 200 ° T 1500 °); aluminum (0 107 sec–1, 300 ° T 900 °); copper (0 105 sec–1, 300 ° T 1300 °); lead (0 106 sec–1, 90 ° T 400 °); temperatures in °K.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 4, pp. 114–118, July–August, 1974. 相似文献