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41.
N.I. Morrell † R.H. Barbá † V.S. Niemela ‡ M.A. Corti § J.F. Albacete Colombo G. Rauw ¶ M. Corcoran T. Morel J.-F. Bertrand A.F.J. Moffat N. St-Louis 《Monthly notices of the Royal Astronomical Society》2001,326(1):85-94
A new high-quality set of orbital parameters for the O-type spectroscopic binary HD 93205 has been obtained combining échelle and coudé CCD observations. The radial velocity orbits derived from the He ii λ 4686 Å (primary component) and He i λ 4471 Å (secondary component) absorption lines yield semi-amplitudes of 133±2 and 314±2 km s−1 for each binary component, resulting in minimum masses of 31 and 13 M⊙ ( q =0.42) . We also confirm for the binary components the spectral classification of O3 V+ O8 V previously assigned. Assuming for the O8 V component a 'normal' mass of 22–25 M⊙ we would derive for the primary O3 V a mass of 'only' 52–60 M⊙ and an inclination of about 55° for the orbital plane. We have also determined for the first time a period of apsidal motion for this system, namely 185±16 yr using all available radial velocity data sets of HD 93205 (from 1975 to 1999). Phase-locked variations of the X-ray emission of HD 93205 consisting of a rise of the observed X-ray flux near periastron passage are also discussed. 相似文献
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G. Rauw † H. Sana I.I. Antokhin N.I. Morrell ‡ V.S. Niemela § J.F. Albacete Colombo ¶ E. Gosset J.-M. Vreux 《Monthly notices of the Royal Astronomical Society》2001,326(3):1149-1160
We discuss the orbital elements of the multiple system Tr 16-104 which is usually believed to be a member of the open cluster Trumpler 16 in the Carina complex. We show that Tr 16-104 could be a hierarchical triple system consisting of a short-period (2.15 d) eclipsing O7 V+O9.5 V binary bound to a B0.2 IV star. Our preliminary orbital solution of the third body indicates that the B star most probably describes an eccentric orbit with a period of ∼285 or ∼1341 d around the close binary. Folding photometric data from the literature with our new ephemerides, we find that the light curve of the close binary exhibits rather narrow eclipses indicating that the two O stars must be well inside their Roche lobes. Our analysis of the photometric data yields a lower limit on the inclination of the orbit of the close binary of i ≥77° . The stellar radii and luminosities of the O7 V and O9.5 V stars are significantly smaller than expected for stars of this spectral type. Our results suggest that Tr 16-104 lies at a distance of the order of 2.5 kpc and support a fainter absolute magnitude for zero-age main-sequence O stars than usually adopted. We find that the dynamical configuration of Tr 16-104 corresponds to a hierarchical system that should remain stable provided that it suffers no strong perturbation. Finally, we also report long-term temporal variations of high-velocity interstellar Ca ii absorptions in the line of sight towards Tr 16-104. 相似文献
45.
Acoustic study of the Rio de la Plata estuarine front 总被引:1,自引:0,他引:1
Cabreira A.G.; Madirolas A.; Alvarez Colombo G.; Acha E.M.; Mianzan H.W. 《ICES Journal of Marine Science》2006,63(9):1718-1725
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Alfredo Aparicio Colombo C.G. Tassinari Roberto García Vicente Araña 《Journal of Volcanology and Geothermal Research》2010,189(1-2):143-150
The lavas produced by the Timanfaya eruption of 1730–1736 (Lanzarote, Canary Islands) contain a great many sedimentary and metamorphic (metasedimentary), and mafic and ultramafic plutonic xenoliths. Among the metamorphosed carbonate rocks (calc-silicate rocks [CSRs]) are monomineral rocks with forsterite or wollastonite, as well as rocks containing olivine ± orthopyroxene ± clinopyroxene ± plagioclase; their mineralogical compositions are identical to those of the mafic (gabbros) and ultramafic (dunite, wherlite and lherzolite) xenoliths. The 87Sr/86Sr (around 0.703) and 143Nd/144Nd (around 0.512) isotope ratios of the ultramafic and metasedimentary xenoliths are similar, while the 147Sm/144Nd ratios show crustal values (0.13–0.16) in the ultramafic xenoliths and mantle values (0.18–0.25) in some CSRs. The apparent isotopic anomaly of the metamorphic xenoliths can be explained in terms of the heat source (basaltic intrusion) inducing strong isotopic exchange (87Sr/86Sr and 143Nd/144Nd) between metasedimentary and basaltic rocks. Petrofabric analysis also showed a possible relationship between the ultramafic and metamorphic xenoliths. 相似文献
48.
Systematic GIS-based landslide inventory as the first step for effective landslide-hazard management 总被引:1,自引:1,他引:1
The purpose of the so-called IFFI project (Inventario dei Fenomeni Franosi in Italia—Inventory of Landslides in Italy) and of many other related activities carried out by the Centro Regionale per le Ricerche Territoriali e Geologiche of ARPA Piemonte (Agenzia Regionale per la Protezione Ambientale—Regional Agency for Environmental Protection), is to map all the existing landslides in Piemonte (including both results of monitoring data and available historical data). ARPA carried out new systematic surveys using
airphoto interpretation and created a specific alphanumeric geological information systems (GIS)-based database to store and
process all the collected data. In order to obtain proper landslide-hazard zoning, it is necessary to provide a landslide
inventory and to define the relationship between landslides and geological setting. A landslide inventory represents a fundamental
base of knowledge, is a very basic tool for land planning, and strongly helps the local authorities in their decision making. 相似文献
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50.
Summary We show that daily precipitation is characterized by a behaviour regulated by power laws. Both for the frequency distribution
of both event intensity and drought duration. In this respect, precipitation appears to follow self-organized criticality
laws, much as other geophysical phenomena such as avalanches and earthquakes. We use this feature to validate the simulation
of daily precipitation events in a multi-decadal regional climate model experiment for the European region. Our focus is on
the Italian peninsula and we show that both the model results and the station observations for daily precipitation intensity
and drought length follow power laws with comparable values of the relevant parameters. We suggest that complex systems theory
can provide useful tools for the validation of precipitation statistics in climate models. 相似文献