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Radio surveys of supernova remnants (SNRs) in the Galaxy have discovered 19 SNRs which are accompanied by the OH maser emission at 1720 MHz. This unusual maser is thought to be produced behind a shock front when a SNR expands into a molecular cloud. An important ingredient of this model is that the X-ray emission from the remnant enhances the production of OH molecules. In this sense, to study the characteristics of the mixed-morphology SNRs accompanied by the OH maser emission at 1720 MHz is important. By studying the X-ray characteristics of the mixed-morphology SNRs accompanied by the 1720 MHz OH maser emission, it is found that the ionization rate of X-ray is not correlated with the physical parameters , D, r, r2 and so on, but is correlated with the X-ray luminosity Lx. Meanwhile, Lx is closely correlated with the beam flux density of the weakest feature of the accompanying 1720 MHz OH maser emission. These mean that the X-ray emission from SNRs is sufficient to dissociate the water molecules behind a shock front and to produce the 1720 MHz OH masers. 相似文献
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The hyperfine-structure lines of highly charged ions may allow one to look at hot rarefied astrophysical plasmas from a new
perspective. In this paper, we discuss the spectral lines of ions and isotopes abundant at temperatures 105–107 K characteristic of a warm-hot intergalactic gas, a hot interstellar medium, starburst galaxies, their superwinds, and young
supernova remnants. Observations of these lines will make it possible to study the bulk and turbulent motions in the observed
objects and will supplement the information about the ionization state and chemical and isotopic compositions of the gas.
The line of the main nitrogen isotope with wavelength λ = 5.65 mm is of particular interest. The wavelength of this line is
well suited for observations of objects at z ≈ 0.15−0.6, when it is redshifted to the spectral range 6.5–9 mm widely used in ground-based radio observations, and, for
example, for z ≥ 1.3, when the line is redshifted to 1.3 cm or farther. Modern and future radio telescopes and interferometers are capable
of observing the 14N VII absorption by the warm-hot intergalactic gas at redshifts higher than z ≈ 0.15 in the spectra of the brightest millimeter-band sources. The submillimeter emission lines of the most abundant isotopes
with hyperfine splitting may also be detected in the spectra of young supernova remnants.
The article was translated by the authors. 相似文献
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Y. E. Lyubarsky 《Monthly notices of the Royal Astronomical Society》2002,329(2):L34-L36
Origin of the jet-like feature in the inner Crab Nebula is discussed. Because self-collimation processes in ultrarelativistic pulsar winds are extremely ineffective, it is suggested that the collimation occurs beyond the termination shock where the flow is already mildly (or non-) relativistic. It is argued that the shock shape is highly non-spherical because the energy flux in the pulsar wind decreases towards the axis. The shock near the axis should be much closer to the pulsar than at the equator and therefore the jet looks as if it originates directly from the pulsar. 相似文献
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