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51.
Gisbert Winnewisser 《Journal of Molecular Spectroscopy》1973,46(1):16-24
The millimeter wave spectrum of propynal, HCCCHO, has been studied in the ground vibrational state. A detailed centrifugal distortion analysis has been carried out on the combined data of newly assigned millimeter wave rotational transitions (up to 200 GHz) together with the microwave transitions reported earlier. A total of 90 transitions as high as J = 20 and K = 12 could be fitted with a standard deviation of 87 kHz. This analysis yielded a complete set of ground state rotational and centrifugal distortion constants. The rotational constants are in MHz: 相似文献
52.
Giovanni Moruzzi Brenda P. Winnewisser Manfred Winnewisser 《Journal of Molecular Spectroscopy》2003,219(1):152-162
Oxetane is a four-membered ring molecule exhibiting a large-amplitude ring-puckering motion. In order to analyze this vibration we recorded a rotationally resolved far-infrared spectrum between 50 and 145 cm−1. The analysis of the ring-puckering fundamental band with the assignment of 1108 lines, has been presented in a previous paper. In the present work we present a list of further 6531 assigned transitions between the five lowest excited ring-puckering states. The 4983 term values involved in the transitions assigned in this and in the preceding work have been evaluated by the “Ritz” program, and are now available. An A-reduced Watson Hamiltonian in any of the three representations Ir, IIr, and IIIr was used to perform a fit of the assigned transitions. Precise rotational constants and quartic as well as a full set of sextic centrifugal distortion constants were obtained for the investigated ring-puckering states. For the first time, high-resolution values for the vibrational Gv parameters have been obtained, and we have added terms in x6 and x8 to the double minimum-potential well describing the ring-puckering motion, in order to reproduce their values within the experimental accuracy. The same potential still reproduces the lower resolution values of the Q-branch origins involving higher ring-puckering states up to vrp=14 found in the previous literature. 相似文献
53.
Two-dimensional hydrodynamic calculations for a self-gravitating, magnetic and compressible medium are carried out. The results based on numerical simulations show that the joint effect of the nonlinearity of the hydrodynamic equations and self-gravity is the mechanism for generating the observed complex structure of molecular clouds (e.g. clumps and filaments). In addition, parameters such as the evolution time of molecular clouds, the density contrast, fractal dimension, and the velocity probability distribution are derived. Their possible relation to the observed properties of molecular clouds are discussed. 相似文献
54.
Th. Klaus A. H. Saleck S. P. Belov G. Winnewisser Y. Hirahara M. Hayashi E. Kagi K. Kawaguchi 《Journal of Molecular Spectroscopy》1996,180(2):197-206
Pure rotational spectra of rare isotopomers of sulfur monoxide, SO, have been recorded with the Cologne Terahertz Spectrometer, Germany, and the millimeter- and submillimeter-wave spectrometer at Nobeyama, Japan. In total, 176 new transitions have been measured in theX3Σ−electronic ground state, including the first laboratory detection of the rare isotopomer36SO. New lines are also reported for33SO and S17O in their vibrational ground states, and for33SO and S18O in the first excited vibrational state. A simultaneous fit of 451 transitions has led to an improved set of isotopically invariant parameters for rotation and fine structure. Hyperfine structure constants for33SO and S17O have been obtained also from the global fit, including first values for the magnetic nuclear spin–rotation interaction. These are compared to other molecules. The isotopically invariant parameters allow precise frequency predictions for the submillimeter-wave region far beyond 1 THz for all SO isotopomers, of importance to astrophysical applica- tions. 相似文献
55.
Both the temporal and the spatial Kelvin-Helmholtz instability of a hypersonic jet confined by a longitudinal magnetic field are investigated. The reflection modes are calculated for a set of typical jet parameters. Analytical treatments for both temporal and spatial resonant modes, i.e., the most important reflection modes with the local maximum growth rates, are given. Various properties of the resonant modes are plotted against the jet temperature. The growth rates of the temporal and the spatial resonant modes are connected by the group velocity. The astrophysical implications of the present investigation are discussed. 相似文献
56.
G. Winnewisser R.A. Cornet F.W. Birss R.M. Gordon D.A. Ramsay S.M. Till 《Journal of Molecular Spectroscopy》1979,74(2):327-329
The two isotopic species CH2DCOOH and CH2DCOOD of acetic acid have been investigated with microwave spectroscopy in order to determine the equilibrium configuration of the methyl group, which was found to be eclipsed with respect to the carbonyl group. Centrifugal distortion constants free from internal rotation effects have been determined. A rs structure for the four hydrogens and a partial r0 structure for the whole molecule are given. 相似文献
57.
Manfred Winnewisser Brenda P. Winnewisser Monika SteinManfred Birk Georg WagnerGisbert Winnewisser Koichi M.T. Yamada Sergey P. Belov Oleg I. Baskakov 《Journal of Molecular Spectroscopy》2002,216(2):259-265
While the rotational spectrum of trans-HCOOH is well known, the cis-rotamer was known previously only from a few microwave transitions. The spectra of cis- and trans-HCOOH and of trans-H13COOH have been identified in the far infrared Fourier transform spectrum recorded in the range 20-100 cm−1. The measurements were performed using an 80-cm base length White-type multipass absorption cell in combination with a Bruker IFS 120 HR spectrometer. The White cell was set up for 90 passes (total path length=72 m) and the spectrum was measured with a resolution (FWHM) of 0.0012 cm−1. Submillimeter-wave transitions, just under 1 terahertz, of the same three species of formic acid were measured in the range from 835 to 993 GHz (27.8-33.1 cm−1) and it was possible to assign b-type Q-branch transitions of both cis- and trans-HCOOH in this region, and also transitions of trans-H13COOH. These measurements served furthermore as a check on the calibration of the FTIR measurement. Furthermore, new millimeter-wave measurements in the range 172-366 GHz were made, bridging the gap between the MW and FIR lines for cis-HCOOH and providing important data for trans-H13COOH. The assigned FTIR, submillimeter- and millimeter-wave data reported in this work were fitted together with previously published rotational transitions to obtain rotational constants, using Watson's A-reduced Hamiltonian, for cis-HCOOH, trans-HCOOH, and trans-H13COOH. 相似文献
58.
Müller HS Klein H Belov SP Winnewisser G Morino I Yamada KM Saito S 《Journal of Molecular Spectroscopy》1999,195(1):177-184
The rotational spectrum of the NH2 radical in its &Xtilde;2B1 ground vibronic state was investigated between 614 and 1003 GHz. One hundred fifty-nine newly observed lines (188 hyperfine components) of six rotational transitions with 0 = N = 5 and 0 = Ka = 4 were used in the final, global fit of field-free data for the (000) vibrational state. Recent results from Fourier transform far-infrared (FT-FIR), and millimeter- and submillimeter-wave spectroscopy, as well as microwave optical double resonance (MODR) and recent FIR laser sideband data, were also used in the fit. A large set of spectroscopic constants reproduces the input data within experimental uncertainties and permits the precise prediction of low-N, low-Ka transitions of interest for the astrophysical community. In particular, the astrophysically important 111-000 transition of ortho NH2 was observed near 952.57 and 959.50 GHz. Copyright 1999 Academic Press. 相似文献
59.
Brenda P. Winnewisser Manfred Winnewisser Flemming Winther 《Journal of Molecular Spectroscopy》1974,51(1):65-96
A quasilinear molecular model is needed to account for the infrared absorption spectrum of HCNO and DCNO in the spectral region from 100 cm?1 to 1000 cm?1. The observed systems of infrared bands arising from the ν5 vibrational manifold have all been assigned. The rotational structure of the absorption bands at 225 cm?1, 275 cm?1, 315 cm?1, and 317 cm?1 for HCNO has been resolved using a Fourier spectrometer. The rotational constants and the band centers have been determined for the above bands, which represent the transitions(0000011)c←0000000(0000022)c,d←(0000011)c,dboth components(0000033)c,d←(0000022)c,d0000020←(0000011)c.By means of the Ritz combination principle the infrared transitions could be used to build up the vibrational energy level scheme of the ν5 vibrational mode for HCNO and DCNO. The data are only reconcilable with a potential function for ν5 which exhibits a low barrier opposing linearity. Preliminary values of the potential parameters were obtained using different approximate theoretical approaches.A reinterpretation of the r8 structure parameters of fulminic acid in the light of the quasilinear model leads to an explanation of the extraordinarily short CH internuclear distance of 1.027 Å as the projection of a CH bond length of 1.060(5) Å upon the heavy-atom axis.The isotopic shift upon deuteration observed in the infrared data indicate that the ν5 fundamental vibration is primarily an HCN bending motion. The ν4 fundamental vibration (skeletal bending motion) of HCNO is located at 537 cm?1 and does not exhibit any hot band structure which would be indicative of a perturbed potential function. 相似文献
60.
Walsh MS Xu LH Lees RM Mukhopadhyay I Moruzzi G Winnewisser BP Albert S Butler RA DeLucia FC 《Journal of Molecular Spectroscopy》2000,204(1):60-71
New millimeter-wave and microwave measurements for CH(3)OD have been combined with previous literature data and with an extended body of Fourier transform far-infrared observations in a full global analysis of the first two torsional states (v(t) = 0 and 1) of the ground vibrational state. The fitted CH(3)OD data set contained 564 microwave and millimeter-wave lines and 4664 far-infrared lines, representing the most recent available information in the quantum number ranges J = 20 and K = 15. A 53-parameter converged global fit was achieved with an overall weighted standard deviation of 1.060, essentially to within the assigned measurement uncertainties of +/-100 kHz for almost all of the microwave and millimeter-wave lines and +/-6 MHz for the far-infrared lines. The new parameters for CH(3)OD are compared to previous results obtained for the (12)CH(3)OH, (13)CH(3)OH, and CD(3)OH isotopomers over the same quantum number ranges using the identical fitting program. Strong asymmetry-induced coupling between the accidentally near-degenerate 0E and -1E v(t) = 0 substates is successfully modeled by the fit. Copyright 2000 Academic Press. 相似文献