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81.
据观测到的SN1996的Hα谱线的初步计算结果表明,该超新星可能是由一颗晚B9型超新星爆发形成的,爆发时的气壳质量可达0.0031M⊙,径向膨胀速度为11760km/s。 相似文献
82.
83.
84.
Colliding Blast Waves Driven by the Interaction of a Short-Pulse Laser with a Gas of Atomic Clusters
Roland A. Smith James Lazarus Matthias Hohenberger Alastair S. Moore Joseph S. Robinson Edward T. Gumbrell Mike Dunne 《Astrophysics and Space Science》2007,307(1-3):131-137
Collisions between shocks are commonly found in many astrophysical objects, however robust numerical models or laboratory
analogues of these complex systems remain challenging to implement. We report on the development of scaled laboratory experiments
which employ new techniques for launching and diagnosing colliding shocks and high Mach number blast waves, scalable to a
limited subset of astrophysically-relevant regimes. Use of an extended medium of atomic clusters enables efficient (>80%)
coupling of 700 fs, 1 J, 1054 nm laser pulses to a “cluster” gas with an average density of ≈1019 particles cm−3, producing an initial energy density >105 J cm−3, equivalent to ≈5×109 J/g. Multiple laser foci are used to tailor the spatial profile of energy deposition, or to launch pairs of counter-propagating
cylindrical shocks which then collide. By probing the collision interferometrically at multiple view angles in 5^ increments and applying an inverse Radon transform to the resulting phase projections we have been able to tomographicall
reconstruct the full three-dimensional, time-framed electron density profile of the system. 相似文献
85.
M.F. Graham R.J. Smith J. Meaburn M. Bryce 《Monthly notices of the Royal Astronomical Society》2001,326(2):539-542
The giant filamentary shell, DEM 171, is found to be expanding at approximately 37 km s−1 . A supernova and stellar wind origin are both explored as possible causes for the expanding shell. A stellar wind origin would imply a mass-loss rate of the order of 10−5 M⊙ yr−1 , indicating that it could be caused by a Wolf–Rayet star. A number of blue stars are found to lie within the shell and one is identified as a Wolf–Rayet candidate. 相似文献
86.
T. Morel R. Doyon N. St-Louis 《Monthly notices of the Royal Astronomical Society》2002,329(2):398-410
In an effort better to calibrate the supernova rate of starburst galaxies as determined from near-infrared [Fe ii ] features, we report on a [Fe ii ] λ 1.644 μm line-imaging survey of a sample of 42 optically selected supernova remnants (SNRs) in M33. A wide range of [Fe ii ] luminosities are observed within our sample (from less than 6 to 695 L⊙ ). Our data suggest that the bright [Fe ii ] SNRs are entering the radiative phase and that the density of the local interstellar medium (ISM) largely controls the amount of [Fe ii ] emission. We derive the following relation between the [Fe ii ] λ 1.644 μm line luminosity of radiative SNRs and the electronic density of the post-shock gas, n e : L [Fe ii ] (cm−3 ). We also find a correlation in our data between L [Fe ii ] and the metallicity of the shock-heated gas, but the physical interpretation of this result remains inconclusive, as our data also show a correlation between the metallicity and n e . The dramatically higher level of [Fe ii ] emission from SNRs in the central regions of starburst galaxies is most likely due to their dense environments, although metallicity effects might also be important. The typical [Fe ii ]-emitting lifetime of a SNR in the central regions of starburst galaxies is found to be of the order of 104 yr. On the basis of these results, we provide a new empirical relation allowing the determination of the current supernova rate of starburst galaxies from their integrated near-infrared [Fe ii ] luminosity. 相似文献
87.
S. O. Tagieva 《Astronomy Letters》2002,28(5):310-315
The dependences of various parameters for S-and C-type supernova remnants (SNRs) on their diameters are investigated. Only SNRs with D≤40 pc that expand initially within H II regions and, subsequently, in dense media are considered. The expansion velocities and thermal electron densities of these SNRs were found to decrease with increasing diameter, on average, as D ?1 and D ?0.5, respectively. H II regions hamper the detection of SNRs; this effect is particularly pronounced in regions with 270°≤1≤300° and 330°≤1≤360°. The X-ray luminosities of SNRs born in dense media increase by an order of magnitude when their diameters reach ~30 pc. After the SNR diameters reach ~40 pc, their radio and X-ray luminosities decrease sharply. 相似文献
88.
Sidney Van den Bergh 《Journal of Astrophysics and Astronomy》1980,1(1):67-70
A massive binary, in which the primary becomes a supernova, should leave a luminous secondary near the centre of its remnant.
Contrary to expectation no statistically significant excess of OB stars is, however, found near the centres of optically visible
galactic supernova remnants. 相似文献
89.
We use the recently introduced concept of a ‘window’ of magnetic field strengths in which pulsars can be active to explain
the variation in morphology of supernova remnants. The striking difference between shell-type and filled-type remnants is
attributed to differences in he magnetic field strengths of the neutron stars left by the respective Supernovae. Field strengths
of a value permitting pulsar activity result in particle production and Crab-like centrally concentrated remnants. Other field
values lead to strong magnetic dipole radiation and consequent shell formation (e.g. Cas A). Several apparent inconsistencies concerning pulsar-supernova associations appear to find a logical explanation on
the basis of this hypothesis. 相似文献
90.
Based on observations of SN 1999em, we determined the physical parameters of this supernova using hydrodynamic calculations including nonequilibrium radiative transfer. Taking the distance to SN 1999em estimated by the expanding photosphere method (EPM) to be D = 7.5 Mpc, we found the parameters of the presupernova: radius R = 450R⊙, mass M = 15M⊙, and explosion energy E = 7 × 1050 erg. For the distance D = 12 Mpc determined from Cepheids, R, M, and E must be increased to the following values: R = 1000R⊙, M = 18M⊙, and E = 1051 erg. We show that one cannot restrict oneself to using the simple analytical formulas relating the supernova and presupernova parameters to obtain reliable parameters for type-IIP presupernovae. 相似文献