全文获取类型
收费全文 | 57篇 |
免费 | 0篇 |
专业分类
化学 | 46篇 |
力学 | 7篇 |
物理学 | 4篇 |
出版年
2018年 | 1篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 6篇 |
1999年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有57条查询结果,搜索用时 31 毫秒
1.
2.
A. V. Belyakov A. V. Golubinskii L. V. Vilkov V. I. Shiryaev E. M. Styopina E. A. Kovalyova V. S. Nikitin 《Russian Chemical Bulletin》1993,42(2):346-349
The molecular structure of gaseous Br2Sn(CH2SiMe2)2O was studied by electron diffraction. The six-membered ring has a chair conformation whereas the entire molecule possessesC
s
symmetry. The existence of a boat conformer cannot be completely excluded. The results of theoretical calculations for a twisted-boat conformation are at variance with the experimental data. Steric strain caused by mutual repulsion of the two axial methyl groups is reduced to the tilt of the Me2Si fragments in opposite directions. This results in an increase (up to 26°C) in the angle formed by the bisector of the CM-Si-CM angle with the CcSiO plane. The main geometrical parameters are as follows:r
g (Å): Si-O 1.708(20); Si-CM 1.862(20); Si-Cc 1.882(9); Sn-C 2.108(26); Sn-Br 2.456(3); C-H 1.099(30); (degr.): C-Sn-C 105(2); Br-Sn-Br 107.9(1.2); Si-O-Si 129.6(3); CM-Si-CM 112; Si-C-H 113 (fixed value in accordance with experiment); Cc-Si-O 107(2); Sn-C-Si 109(2); torsion angles: (Si-C) 52(2); (Si-O) 62(1); (Cc-Sn) 54(1). The average amplitudes were fixed at the values calculated from the force field. Structural parameters of molecules with similar structures were analyzed and compared.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 384–387, February, 1993. 相似文献
3.
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
4.
5.
6.
The phenomenon of noncoherent wave reflection associated with scattering by electromagnetic fluctuations in a semibounded plasma-molecular medium is studied. The differential reflection coefficients are computed for scattering by collective bulk and surface fluctuations.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 79–82, May, 1987. 相似文献
7.
L.S. Khaikin O.E. Grikina A.V. Golubinskii R.E. Asfin 《Journal of Molecular Structure》2003,658(3):153-170
The molecular structure of the hydrogen bonded cyclic dimer of dimethylphosphinic acid (Me2P(O)OH)2 was determined by gas-phase electron diffraction (GED) at 433 K. The presence of monomer cannot be determined at this temperature within the error limits for the GED method. Structural analysis was performed with consideration of non-linear kinematic effects at the first-order level of perturbation theory (h1). The vibrational characteristics of internuclear distances were calculated from a priori scaled quantum chemical (RHF/6-311G**) force field. The analysis aided by a constraint based on the RHF/6-311G** calculations yielded the following rh1-parameters of the C2-symmetry dimer configuration: PO 1.497(3); P-O 1.573(4); P-C 1.806(1) and 1.811(1) Å; (C-H)av. 1.109(3) Å; ∠O-PO 120(1)°. Unlike PO and P-O bonds, whose lengths in the gas phase and in the solid state differ insignificantly, the -O?O distance in the gas phase (rh1 2.81(4) Å) is considerably longer than in the solid state (rα 2.48(2) Å). The latter is in accordance with the conclusion based on the IR spectra that transition from gas to a solid sample leads to strengthening of the H-bonds. Due to its small contribution to the diffraction pattern, the donor O-H bond length (rh1 0.99(1) Å) was forcedly bound up with the parameters of C-H bonds. With this assumption, the other geometrical parameters characterizing the H-bond fragment have the following rh1 values: O?H 1.84(4) Å, ∠-OHO164(6)°, and ∠P-O-H 117(4)°. Conformational flexibility of the non-planar eight-atom ring of the dimer is experimentally verified by absence of any apparent peaks of the f(r) curve at the r-region of more than 4.2 Å. 相似文献
8.
9.
A. V. Shastin I. V. Golubinskii O. N. Lenkova E. S. Balenkova V. G. Nenaidenko 《Russian Journal of Organic Chemistry》2006,42(2):238-240
A new procedure was developed for preparation of ethyl 3-amino-5-arylthiophene-2-carboxylates by the reaction of α-chlorocinnamonitriles and their analogs with ethyl mercaptoacetate for a wide range of substrates. The reaction products form in high yields. 相似文献
10.
Atavin E. G. Golubinskii A. V. Popik M. V. Khristenko L. V. Gloriozov I. P. Salgalov A. A. Ustynyuk Yu. A. Vilkov L. V. 《Russian Chemical Bulletin》2003,52(5):1106-1110
The molecular structure of 6-(N,N-dimethylamino)fulvene was studied by gas-phase electron diffraction and quantum-chemical methods (HF/6-31G(d), MP2/3Z, MP2/4Z, density functional theory with the B3LYP/6-31G(d) and PBE/3Z functionals). Pronounced flattening of the nitrogen atom and equalization of the intracyclic C—C bonds were found to be a consequence of the electron delocalization in the molecule. 相似文献