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1.
2.
A.V. Belyakov L.S. Khaikin L.V. Vilkov E.T. Bogoradovsku V.S. Zavgorodnii 《Journal of Molecular Structure》1981
The geometrical parameters of the tetraphenyltin molecule have been determined by gas phase electron diffraction at about 310°. The S4 and “open” D2d molecular models with the tetrahedral bond configuration at tin were chosen for the structure analysis. The former gave the better fit. The thermal average bond lengths (rg, in Å) are as follows: The benzene ring geometry appears to be almost unaffected by bonding to tin. However, tin causes an increase in the endocyclic valence angle at the ipso-carbon atom to 121.0(0.9)° rather than a decrease of that angle as might be expected, tin being a σ-electron donor. The ring plane and the plane containing the bond and S4 axis make an angle, ?, of 34.1(2.1)°. The bond length in tetraphenyltin is longer than not only the bond in tetravinyltin (rg = 2.117(4) Å) but also the bond in tetramethyltin (rg = 2.144(7) A). 相似文献
3.
L.S. Khaikin A.V. Belyakov L.V. Vilkov E.T. Bogoradovskii V.S. Zavgorodnii 《Journal of Molecular Structure》1980
The geometrical parameters of tetraethynyltin and triethynyltin iodide have been determined by gas-phase electron diffraction. Triethynyltin iodide was present as an admixture in both the tetraethynyltin samples studied. Because the samples differed significantly in percentage of the iodide (17.4 ± 4.0 and 47.1 ± 3.5 mol %, in samples A and B, respectively), it was possible to determine the structures of both molecules to a sufficient degree of accuracy.The rα, structures were solved by the least-squares treatment of the molecular intensities, using mean amplitudes and shrinkage corrections calculated from the force fields of a number of tin derivatives.The Td-symmetry model of Sn(CCH)4 was refined to give the following parameters: Sn-C, 2.068(5); CC, 1.228(8); CH, 1.079(51). The structural parameters for ISn(CCH)3 (on the basis of the C3v model with linear Sn-CC-H fragments) are as follows: Sn-I, 2.646(4); Sn-C, 2.062(17); CC, 1.226(6); ∠ISnC 108.0(2.8). (The thermal average bond distances, rg, are given in Å, and the valence angle, rα, in degrees; the values in paren- theses are three times the standard deviations, 3σ.)The Sn-C bonds in Sn(CCH)4, and ISn(CCH)3 are shorter than the corresponding bonds in the monoethynyltin derivatives, Me3SnCCH and Me3SnCCSnMe3. The SnI bond in ISn(CCH)3 is noticeably shorter than those in stannane iodide and trimethylstannane iodide. 相似文献
4.
V. A. Shlyapochnikov L. S. Khaikin O. E. Grikina N. O. Cherskaya L. E. Maksimova N. F. Pyatakov 《Russian Chemical Bulletin》1998,47(11):2173-2176
Vibrational spectra of several nitramines in the long-wave region (50–450 cm−1) were studied. The frequencies of intra- and intermolecular vibrations were separated and a tentative assignment of the frequencies
of self-associative complexes was performed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2241–2244, November, 1998. 相似文献
5.
L. S. Khaikin O. E. Grikina L. V. Vilkov J. E. Boggs 《Journal of Structural Chemistry》1993,34(1):9-16
For five N-nitramines (H2NNO2, MeNHNO2, ClNHNO2, MeNClNO2, Me2NNO2) using the program GAUSSIAN-90 we have carried out quantum chemical calculations by the restricted Hartree—Fock method, taking into account electron correlation by second-order Møller—Plesset perturbation theory in a standard 6–31G* basis. In this paper, we consider the transition states for inversion of the amine nitrogen atom and rotation about the NN bond. We have obtained data on the changes in the geometric parameters during inversion and rotation. The changes in the NN bond length are especially significant they increase by 0.06–0.08 Å in the transition states for internal rotation compared with the equilibrium forms. We have calculated the barriers to inversion and internal rotation, the height of which strongly depends on the electronegativity of the substituents on the amine nitrogen atom. Estimates of the barriers to inversion lie within the range 0.4–6.0 kcal/mole while estimates of the barriers to rotation lie within the range 6–13 kcal/mole, which are 1.5–2 times lower than in amides and N-nitrosoamines.Moscow State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 1, pp. 12–19, January–February, 1993. 相似文献
6.
L. S. Khaikin E. A. Zhilinskaya O. E. Grikina M. V. Proskurnina L. V. Vilkov 《Journal of Molecular Structure》1995,356(3):239-246
The relative energies and structural parameters of the equilibrium forms and the potential functions of internal rotation of methylphosphonic dicyanide, CH3(=O)(CN)2, methoxydicyanophosphine, CH3OP(CN)2, and their isocyano analogs, CH3P(=O)(NC)2 and CH3OP(NC)2, have been calculated at the RHF/6-31G* level. The total energy of the more stable oxo forms CH3P(=O)(CN)2 and CH3P(=O)(NC)2 are 10–20 kcal mol−1 lower than the energies of the aci forms CH3OP(CN)2 and CH3OP(NC)2. The relative stabilities of the cyano and isocyano isomers are almost the same in the case of the oxo forms, but for the aci forms the energies of the cyano isomers are 8 kcal mol−1 lower than those of the isocyano isomers. The potential curves for internal rotation in the aci forms are characterized by a deep minimum corresponding to the trans arrangement of the methyl group and the lone pair of electrons on the phosphorus atom. Two less pronounced minima are symmetrically situated with respect to relative maximum corresponding to the transition cis form. The potential curves of internal rotation in the oxo form possess three minima corresponding to staggered configurations of the methyl group and phosphorus atom bonds. The energy characteristics and geometrical parameters of the studied molecules are compared with known data for similar compounds. 相似文献
7.
L.S. Khaikin A.V. Belyakov G.S. Koptev A.V. Golubinskii V.N. Kirin A.S. Kozmin L.V. Vilkov S.S. Yarovoi 《Journal of Molecular Structure》1978,44(1):55-71
A gas phase electron diffraction study of the cage hydrocarbon, basketene, is reported. A least squares treatment of molecular intensities has been carried out in terms of a geometrically consistent rα structure. The mean amplitude values and shrinkage corrections have been calculated using the force field parameters estimated from the data on simpler molecules.Structure refinement of the C2v molecular model yields the following parameter values (bond lengths, ra, in nm; angles, rα in degrees): <C2—C3, C4—C5?av 0.1609(14); C3—C4 0.1563(6); C9C10 0.1360(9); C1—C10 0.1511(13); C1—C2 0.1517(9); <C-H>av. 0.1092(8); <C3C4C7 88.5(1.0); dihedral angle C3C4C7/C3C5C7 153.8(1.0). Parenthesized are three times the standard deviation values, 3σ.In addition to the geometric parameters listed, the mean amplitudes for all bonded and C· C nonbonded distances have been determined by the least squares method. All the other amplitudes (C· H and H· H) have been fixed at the values estimated from the spectral data.Comparison of the results obtained with the literature data on similar polycyclic molecules points to the stronger internal strain in the basketene molecule. 相似文献
8.
The rate constants of reactions of the NO3
radical with hydrazoic acid (7.6 × 106l mol–1s–1) and the hydrazonium ion (2.3 × 106l mol–1s–1) in 6 M nitric acid at 290 ± 2 K were measured by a pulse radiolysis technique. The reaction scheme was refined by the computer simulation of the -radiolysis of aqueous nitric acid solutions of hydrazine with the use of the measured rate constants and published data on the reactivity of intermediates. The results of computations were compared with experimental data on the continuous radiolytic degradation of hydrazine in aqueous 2 M nitric acid solutions at 313 K. 相似文献
9.
V. B. Librovich V. I. Lisitsyn B. I. Khaikin 《Journal of Applied Mechanics and Technical Physics》1974,15(1):61-68
The combustion of a gas suspension of particles reacting in accordance with a heterogeneous mechanism was considered in [1–4]. It was assumed that the reaction rate at the surface of the individual particles does not depend on the thickness of the oxide film, or that a film does not form, i.e., the reaction products are gaseous. With the oxidation of many metals the oxide film formed inhibits the reaction, i.e., with its growth, the rate of the reaction decreases. The special characteristics of the process of the combustion of individual particles of metals arising as a result of the effect of the oxide film were considered in [5], in which it was shown that the dependence of the reaction rate on the thickness of the film has a considerable effect on the laws governing the combustion of individual particles. In the present work, a study was made of the process of the combustion of a gas suspension of particles of metals oxidizing in accordance with the so-called parabolic law (the reaction rate is inversely proportional to the thickness of the oxide film). The results are compared with the laws governing the combusion of a gas suspension of particles reacting in accordance with a purely heterogeneous mechanism in the absence of an oxide film. 相似文献
10.