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71.
A. M. Swinbank R. G. Bower Graham P. Smith Ian Smail J.-P. Kneib R. S. Ellis D. P. Stark A. J. Bunker 《Monthly notices of the Royal Astronomical Society》2006,368(4):1631-1645
We exploit the gravitational potential of massive cluster lenses to probe the emission-line properties of six z = 1 galaxies which appear as highly magnified luminous arcs. Using the Gemini Multi-Object Spectrograph (GMOS) integral field spectrograph together with detailed cluster lens models, we reconstruct the intrinsic morphologies and two-dimensional velocity fields in these galaxies on scales corresponds to ∼0.5 kpc (unlensed) at z = 1 . Four of the galaxies have stable disc-like kinematics, whilst the other two resemble interacting or starburst galaxies. These galaxies lie close to the mean rest-frame I -band Tully–Fisher relation for nearby spirals suggesting a clear preference for hierarchical growth of structure. In the rest-frame B band, the observations suggest 0.5 ± 0.3 mag of brightening, consistent with increased star-formation activity at z = 1 . However, the galaxies with stable disc kinematics have more slowly rising rotation curves than expected from galaxies with similar surface brightness in the local Universe. We suggest that this may arise because the distant galaxies have lower bulge masses than their local counterparts. Whilst this study is based on only six galaxies, the gain in flux and in spatial resolution achieved via gravitational magnification provides a much more detailed view of the high-redshift Universe than that possible with conventional surveys. 相似文献
72.
Michael A. Dopita Michiel Reuland Wil van Breugel Wim de Vries S. A. Stanford Huub Röttgering George Miley Bram Venemans Hy Spinrad Steve Dawson Arjun Dey Mark Lacy Daniel Stern Andrew Bunker 《Astrophysics and Space Science》2007,311(1-3):305-309
We present results from a Keck optical and near IR spectroscopic study of the giant emission line halos of the z>3 High Redshift Radio Galaxies (HiZRGs) 4C 41.17, 4C 60.07 and B2 0902+34. The outer regions of these halos show quiet kinematics
with typical velocity dispersions of a few hundred km s−1 and velocity shears consistent with rotation. The inner regions contain shocked, clumpy cocoons of gas closely associated
with the radio lobes with disturbed kinematics and expansion velocities and/or velocity dispersions >1000 km s−1. We also find evidence for the ejection of chemically enriched material in 4C 41.17 up to a distance of ∼60 kpc along the
radio-axis. We infer that these HiZRGs are undergoing a final jet-induced phase of star formation with the ejection of most
of their interstellar medium before evolving to become “red and dead” Elliptical galaxies. 相似文献
73.
74.
Andrew Bunker Joanna Smith Hyron Spinrad Daniel Stern Stephen Warren 《Astrophysics and Space Science》2003,284(2):357-360
We have discovered extended Lyman-α emission around a z=4.5 QSO in a deep long-slit spectrum with Keck/LRIS at moderate spectral resolution (R≈ 1000). The line emission extends 5 arcsec beyond the continuum of the QSO and is spatially asymmetric. This extended line
emission has a spectral extent of 1000km/s, much narrower in velocity spread than the broad Lyman-α from the QSO itself and
slightly offset in redshift. No evidence of continuum is seen for the extended emission line region, suggesting that this
recombination line is powered by reprocessed QSO Lyman continuum flux rather than by local star formation. This phenomenon
is rare in QSOs which are not radio loud, and this is the first time it has been observed at z>4. It seems likely that the QSO is illuminating the surrounding cold gas of the host galaxy, with the ionizing photons producing
Lyman-α fluorescence. As suggested by Haiman and Rees (2001), this `fuzz' around a distant quasar may place strong constraints
on galaxy formation and the extended distribution of cold, neutral gas.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
75.
76.
Adsorption of cadmium to Bacillus subtilis bacterial cell walls: a pH-dependent X-ray absorption fine structure spectroscopy study 总被引:1,自引:0,他引:1
M.I. Boyanov S.D. Kelly B.A. Bunker D.A. Fowle 《Geochimica et cosmochimica acta》2003,67(18):3299-3311
The local atomic environment of Cd bound to the cell wall of the gram-positive bacterium Bacillus subtilis was determined by X-ray absorption fine structure (XAFS) spectroscopy. Samples were prepared at six pH values in the range 3.4 to 7.8, and the bacterial functional groups responsible for the adsorption were identified under each condition. Under the experimental Cd and bacterial concentrations, the spectroscopy results indicate that Cd binds predominantly to phosphoryl ligands below pH 4.4, whereas at higher pH, adsorption to carboxyl groups becomes increasingly important. At pH 7.8, we observe the activation of an additional binding site, which we tentatively ascribe to a phosphoryl site with smaller Cd-P distance than the one that is active at lower pH conditions. XAFS spectra of several cadmium acetate, phosphate, and perchlorate solutions were measured and used as standards for fingerprinting, as well as to assess the ability of FEFF8 and FEFFIT to model carboxyl, phosphoryl, and hydration environments, respectively. The results of this XAFS study in general corroborate existing surface complexation models; however, some binding mechanism details could only be detected with the XAFS technique. 相似文献
77.
Christopher Leigh rew Collier Cameron Tristan Guillot 《Monthly notices of the Royal Astronomical Society》2003,346(3):890-896
High-resolution spectroscopic searches for the starlight reflected from close-in extrasolar giant planets have the capability of determining the optical albedo spectra and scattering properties of these objects. When combined with radial velocity measurements they also yield the true mass of the planet. To date, only two such planets have been targeted for reflected-light signals, yielding upper limits on the optical albedos of the planets. Here we examine the prospects for future searches of this kind. We present Monte Carlo estimates of prior probability distributions for the orbital velocity amplitudes and planet/star flux ratios of six bright stars known to harbour giant planets in orbits with periods of less than 5 d. Using these estimates, we assess the viability of these targets for future reflected-light searches using 4- and 8-m class telescopes. 相似文献
78.
Barend Van Maanen Giovanni Coco rew Swales Karin R. Bryan 《New Zealand geographer》2008,64(2):162-164
Abstract: Biomorphodynamic interactions, the feedback loops that operate between physical processes, biology and morphology, affect the long-term evolution of estuaries. This paper outlines how consideration of such interactions and implementation through innovative modelling techniques can become the next crucial step needed to advance understanding of estuarine evolution. 相似文献
79.
Kristen Coppin Mark Halpern Douglas Scott Colin Borys James Dunlop Loretta Dunne Rob Ivison Jeff Wagg Itziar Aretxaga Elia Battistelli rew Benson rew Blain Scott Chapman Dave Clements Simon Dye Duncan Farrah David Hughes Tim Jenness Eelco van Kampen Cedric Lacey Angela Mortier Alexandra Pope Robert Priddey Stephen Serjeant Ian Smail Jason Stevens Mattia Vaccari 《Monthly notices of the Royal Astronomical Society》2008,384(4):1597-1610
A follow-up survey using the Submillimetre High-Angular Resolution Camera (SHARC-II) at 350 μm has been carried out to map the regions around several 850-μm-selected sources from the Submillimetre HAlf Degree Extragalactic Survey (SHADES). These observations probe the infrared (IR) luminosities and hence star formation rates in the largest existing, most robust sample of submillimetre galaxies (SMGs). We measure 350-μm flux densities for 24 850-μm sources, seven of which are detected at ≥2.5σ within a 10 arcsec search radius of the 850-μm positions. When results from the literature are included the total number of 350-μm flux density constraints of SHADES SMGs is 31, with 15 detections. We fit a modified blackbody to the far-IR (FIR) photometry of each SMG, and confirm that typical SMGs are dust-rich ( M dust ≃ 9 × 108 M⊙ ) , luminous ( L FIR ≃ 2 × 1012 L⊙ ) star-forming galaxies with intrinsic dust temperatures of ≃35 K and star formation rates of ≃400 M⊙ yr−1 . We have measured the temperature distribution of SMGs and find that the underlying distribution is slightly broader than implied by the error bars, and that most SMGs are at 28 K with a few hotter. We also place new constraints on the 350-μm source counts, N 350 (>25 mJy) ∼ 200–500 deg−2 . 相似文献
80.
Biological damage to plants is commonly found from the Devonian but occurs most commonly from the Cretaceous. Damage inflicted on plants whilst they were alive may trigger a pathological response involving the growth of abnormal tissues. Much of the damage is caused by arthropods, particularly insects. Whilst some damage is non-taxon specific, such as simple feeding traces, other damage, such as leaf mines, galls or bark boring, may reveal the co-evolution of host specific taxa and the timing of such interactions. Damaged plants, particularly from the Cretaceous and Tertiary are described and illustrated. The geological history of the evolution of insect-related plant damage is briefly reviewed. Increased variety in the pathological response of plants is seen from the Cretaceous with the evolution of the angiosperms and diversification of numerous insect groups. 相似文献