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1.
Infrared spectra were obtained for the series of 2,X-dimethylheptanes (X = 2,3,4,5,6) and were interpreted with the aid of normal coordinate calculations. 2,2-DMH exists as two conformers, with the Cs conformer being the only one present in the crystalline solid. 2,3-DMH exists in at least three conformations, all of C1 symmetry. Ambiguities in spectral data indicate that more conformations are present. Two C1 conformations of 2,4-DMH were shown to be present, but an unassigned band may indicate the presence of a third conformer. The presence of at least four conformers, all of C1 symmetry, was shown to be necessary to explain the spectrum of 2,5-DMH. Finally, 2,6-DMH was shown to exist as three conformers, of symmetries Cs, C2, and C1. Vibrational assignments were made for all the probable conformers of all five compounds. 相似文献
2.
Infrared and Raman spectra have been obtained for 1,4-dibromopentane and interpreted with the aid of normal coordinate calculations. It is concluded that all six conformers resulting from rotation about the C1-C2 and C3-C4 bonds probably exist in the neat liquid and amorphous solid, and that the compound crystallizes in the PHSHH conformer that has the two bromine atoms on opposite sides of the plane of carbon atoms. The compound therefore behaves like 1,3-dibromopropane and 1,4-dibromobutane. 相似文献
3.
Infrared and Raman spectra have been obtained for benzyl fluoride and a vibrational assignment has been made. The spectra indicate the presence of a large number of conformers that differ only in the orientation of the C-F bond, as a result of free or nearly free internal rotation. 相似文献
4.
G.A. Crowder 《Molecular physics》2013,111(4):707-715
Normal coordinate calculations were carried out for fluoro-, chloro-, bromo- and iodoacetonitrile, using a seventeen-parameter valence force field. Most of the force constants have different values in the four halides that change in a regular manner. The a″ vibrations are essentially pure, but there is considerable mixing of normal modes in the a′ species. The difference in previous vibrational assignments is resolved but the bands assigned to the C-C-Br and C-C-I bends were found to be mainly C-Br and C-I stretching vibrations. Transferability of the force constants obtained for the CH2Cl group seems quite good. 相似文献
5.
Tvaskis V Christy ME Arrington J Asaturyan R Baker OK Blok HP Bosted P Boswell M Bruell A Cochran A Cole L Crowder J Dunne J Ent R Fenker HC Filippone BW Garrow K Gasparian A Gomez J Jackson HE Keppel CE Kinney E Lapikás L Liang Y Lorenzon W Lung A Mack DJ Martin JW McIlhany K Meekins D Milner RG Mitchell JH Mkrtchyan H Moreland B Nazaryan V Niculescu I Opper A Piercey RB Potterveld DH Rose B Sato Y Seo W Smith G Spurlock K van der Steenhoven G Stepanyan S Tadevosian V Uzzle A Vulcan WF Wood SA 《Physical review letters》2007,98(14):142301
We report on a study of the longitudinal to transverse cross section ratio, R=sigmaL/sigmaT, at low values of x and Q2, as determined from inclusive inelastic electron-hydrogen and electron-deuterium scattering data from Jefferson Laboratory Hall C spanning the four-momentum transfer range 0.06相似文献
6.
7.
Abstract The infrared spectrum of 3-bromo-1,3-dinitroazetidine was interpreted with the aid of normal coordinate calculations. A seventy-two parameter modified valence field was used in those calculations, and the observed wave numbers were fit with an average error of 2.5 cm?1. An assignment of the bands in terms of symmetry coordinates is given. Many of the force constants were transferred to 1-acetyl-3,3-dinitroazetidine to aid in normal coordinate calculations for that compound. 相似文献
8.
G. A. Crowder 《光谱学快报》2013,46(9):1151-1160
Molecular mechanics calculations were made for 1,1-dichlorobutane, 2,2-dichlorobutane, and 1,2-dichloro-2-methylpropane in order to compare the results with conclusions obtained from vibrational spectra concerning the conformational behavior of these compounds. Calculations were also made for 1,2-dichloro-2-methylbutane, although vibrational spectra are not available for this compound. The structures and relative energies of the most abundant conformers are given. 相似文献
9.
The “relaxation” procedure introduced by Held and Karp for approximately solving a large linear programming problem related to the traveling-salesman problem is refined and studied experimentally on several classes of specially structured large-scale linear programming problems, and results on the use of the procedure for obtaining exact solutions are given. It is concluded that the method shows promise for large-scale linear programming 相似文献
10.
G. A. Crowder 《光谱学快报》2013,46(6):639-651
Abstract Infrared spectra were obtained for 2-methylhexane and 3-methylhexane, and were interpreted with the aid of normal coordinate calculations. It was shown that 2-methylhexane exists in three conformations. Evidence for the presence of three conformations of 3-methylhexane is presented, but a fourth conformer probably exists. Transferred force constant values resulted in an overall average difference between observed and calculated wavenumbers of 4.3 cm?1, or 0.5%, for seven conformers of these two compounds. 相似文献