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81.
82.
Hannah H. Kaplan Victoria E. Hamilton Ellen S. Howell F. Scott Anderson M. Antonella Barrucci John Brucato Thomas H. Burbine Beth E. Clark Ed A. Cloutis Harold C. Connolly Elisabetta Dotto Joshua P. Emery Sonia Fornasier Cateline Lantz Lucy F. Lim Frederic Merlin Alice Praet Dennis C. Reuter Scott A. Sandford Amy A. Simon Driss Takir Dante S. Lauretta 《Meteoritics & planetary science》2020,55(4):744-765
The primary objective of the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS‐REx) mission is to return to Earth a pristine sample of carbonaceous material from the primitive asteroid (101955) Bennu. To support compositional mapping of Bennu as part of sample site selection and characterization, we tested 95 spectral indices on visible to near infrared laboratory reflectance data from minerals and carbonaceous meteorites. Our aim was to determine which indices reliably identify spectral features of interest. Most spectral indices had high positive detection rates when applied to spectra of pure, single‐component materials. The meteorite spectra have fewer and weaker absorption features and, as a result, fewer detections with the spectral indices. Indices targeting absorptions at 0.7 and 2.7–3 μm, which are attributable to hydrated minerals, were most successful for the meteorites. Based on these results, we identified a set of 17 indices that are most likely to be useful at Bennu. These indices detect olivines, pyroxenes, carbonates, water/OH‐bearing minerals, serpentines, ferric minerals, and organics. Particle size and albedo are known to affect band depth but had a negligible impact on interpretive success with spectral indices. Preliminary analysis of the disk‐integrated Bennu spectrum with these indices is consistent with expectations given the observed absorption near 3 μm. Our study prioritizes spectral indices to be used for OSIRIS‐REx spectral analysis and mapping and informs the reliability of all index‐derived data products, including a science value map for sample site selection. 相似文献
83.
Ecotoxicological and human health risk in a petrochemical district of southern Italy 总被引:2,自引:0,他引:2
Ausili A Gabellini M Cammarata G Fattorini D Benedetti M Pisanelli B Gorbi S Regoli F 《Marine environmental research》2008,66(1):215-217
An ecotoxicological investigation has been carried in the petrochemical district of Priolo (Sicily, Italy), one of the largest in Europe. Results indicated a severe mercury contamination in sediments sampled near a chloro-alkali plant. A clear bioavailability of this element was demonstrated in mussels Mytilus galloprovincialis (both native and translocated) and the benthic fish Mullus barbatus, which also exhibited marked genotoxic damages. The elevated mercury concentrations in marine organisms are a serious concern for human health; according to the national average fish consumption, the provisional tolerable weekly intake (PTWI) of Hg would be easily exceeded by at least 4 to 12 fold. Such toxicological risk is of particular importance for pregnant women, being possibly involved in the elevated frequency of neonatal malformations. 相似文献
84.
Christiane Hudon Antonella Cattaneo Anne-Marie Tourville Poirier Philippe Brodeur Pierre Dumont Yves Mailhot Jean-Pierre Amyot Simon-Pierre Despatie Yves de Lafontaine 《Aquatic Sciences - Research Across Boundaries》2012,74(3):495-511
Submerged aquatic vegetation (SAV) constitutes a major component of fish habitat, providing support for epiphytes and invertebrates as well as shelter from predators. The effects of wetland epuration from a mesotrophic to a nearly oligotrophic state were examined over a 15?km long reach of the St. Lawrence River under the direct influence of major farmland tributaries. We hypothesized that the nutrient-enriched zone would support a higher biomass of SAV, epiphytes, macroinvertebrates and fish than the nitrogen-deficient epurated zone located downstream of the wetland. Predictions included that the enriched habitat would support a richer fish assemblage, with higher biomass and growth of juvenile yellow perch than found in the epurated zone. Results supported these hypotheses, demonstrating the chain of effects of nutrient reduction on the biomass of SAV (fourfold drop), invertebrate prey (ninefold), small (threefold) and large (1.5-fold) fish between the two zones. In addition to the reduction in SAV biomass, the replacement of filamentous chlorophytes by benthic mats of filamentous cyanobacteria in the epurated zone resulted in a less complex 3-D habitat structure and a low invertebrate availability for fish. Oligotrophication by wetland epuration exerted negative effects on fish habitat quality, food quantity and availability, with an impairment of juvenile perch growth and recruitment. A generalized model of the changes in habitat carrying capacity occurring with epuration (oligotrophication) or eutrophication is presented, with examples of other aquatic systems in which strong linkages between trophic status, SAV, invertebrates and fish productivity were also demonstrated. 相似文献
85.
Geochemical heterogeneities and dynamics of magmas within the plumbing system of a persistently active volcano: evidence from Stromboli 总被引:1,自引:0,他引:1
We report here the most complete dataset for major and trace elements, as well as Sr isotopic compositions, of magmas erupted
by Stromboli since the onset of present-day activity 1,800 years ago. Our data relate to both porphyritic scoria and lava
originating in the uppermost parts of the feeding system, plus crystal-poor pumice produced by paroxysmal explosive eruption
of deep-seated, fast ascending, magma. The geochemical variations recorded by Stromboli’s products allow us to identify changes
in magma dynamics affecting the entire plumbing system. Deep-seated magmas vary in composition between two end-members having
different key ratios in strongly incompatible trace elements and Sr isotopes. These features may be ascribed to mantle source
processes (fluid/melt enrichment, variable degrees of melting) and occasional contamination by deep, mafic, cumulates. Temporal
trends reveal three phases during which magmas with distinct geochemical signatures were erupted. The first phase occurred
between the third and fourteenth centuries AD and was characterised by the eruption of evolved magmas sharing geochemical
and Sr isotopic compositions similar to those of earlier periods of activity (<12 ka—Neostromboli and San Bartolo). The second
phase, which began in the sixteenth century and lasted until the first half of the twentieth century, produced more primitive,
less radiogenic, magmas with the lowest Ba/La and Rb/Th ratios of our dataset. The last phase is ongoing and is marked by
a magma having the lowest Sr isotopic composition and highest Rb/Th ratio of the dataset. While this new magma can be clearly
identified in the pumice erupted during the last two paroxysmal eruptions of 2003 and 2007, shallow degassed magma extruded
during this time span records significant geochemical and isotopic heterogeneities. We thus suggest that the shallow reservoir
has been only partially homogenised by this new magma influx. We conclude that compositional variations within the shallow
magma system of a persistently active volcano provide only a biassed signal of ongoing geochemical changes induced by deep
magma refilling. We argue that source changes can only be identified by interpreting the geochemistry of pumice, because it
reliably represents magma transferred directly from deep portions of the plumbing system to the surface. 相似文献
86.
Antonella Longo Paolo Papale Melissa Vassalli Gilberto Saccorotti Chiara P. Montagna Andrea Cassioli Salvatore Giudice Enzo Boschi 《Bulletin of Volcanology》2012,74(4):873-880
Many volcanic eruptions are shortly preceded by injection of new magma into a pre-existing, shallow (<10 km) magma chamber,
causing convection and mixing between the incoming and resident magmas. These processes may trigger dyke propagation and further
magma rise, inducing long-term (days to months) volcano deformation, seismic swarms, gravity anomalies, and changes in the
composition of volcanic plumes and fumaroles, eventually culminating in an eruption. Although new magma injection into shallow
magma chambers can lead to hazardous event, such injection is still not systematically detected and recognized. Here, we present
the results of numerical simulations of magma convection and mixing in geometrically complex magmatic systems, and describe
the multiparametric dynamics associated with buoyant magma injection. Our results reveal unexpected pressure trends and pressure
oscillations in the Ultra-Long-Period (ULP) range of minutes, related to the generation of discrete plumes of rising magma.
Very long pressure oscillation wavelengths translate into comparably ULP ground displacements with amplitudes of order 10−4–10−2 m. Thus, new magma injection into magma chambers beneath volcanoes can be revealed by ULP ground displacement measured at
the surface. 相似文献
87.
Loreto Rossi M. Letizia Costantini Pasquale Carlino Antonella di Lascio David Rossi 《Aquatic Sciences - Research Across Boundaries》2010,72(2):227-236
The high numbers of primary producers represent multiple sources of organic matter accumulating onto lake bottoms. The difficulty
of distinguishing the relative contribution to the mixture presents considerable challenges to the analysis of these organic
deposits. In this study, dual-stable isotope analysis and IsoSource model were used to identify allochthonous and autochthonous
components of detritus deposits (Particulate Organic Matter: POM) at two different bottom slope sites of a volcanic lake (lake
Bracciano). Experiments were carried out to calibrate IsoSource on constructed plant mixtures and assess changes in isotope
ratios during plant decomposition. IsoSource satisfactorily discriminated the constructed mixture sources with a few exceptions.
Changes in isotopic enrichment during decomposition were low, and thus did not represent a confounding variable in the isotopic
analysis. By contrast, chemical and geological differences of the study sites were associated with differences in plant δ13C and δ15N values (more than 2‰ within single plant species). At both sites, the isotopic signals of POM fell between polygons delineated
by source end members with an evident shift of δ13C toward allochthonous sources. POM amount and diversity were greater at the flatter bottom site, where allochthonous contributions
were larger than at the other site. In particular, IsoSource ranked species contributions as follows: A. glutinosa > P. australis > A. donax > S. alba > P. nigra > the benthic macroalga Chara sp. at the first site, and A. glutinosa > P. nigra > the aquatic macrophyte C. demersum at the latter. The composition of littoral POM was determined by allochthonous sources in proportion to their relative abundances
(as percent land cover) with differences between sites due to bottom slope. 相似文献
88.
Cecilia Battocchi Magda Vila Samuela Capellacci Albert Reñé Antonella Penna 《Marine pollution bulletin》2010,60(7):1074-7059
A molecular PCR-based assay was developed and applied to macrophyte and seawater samples containing mixed microphytobenthic and phytoplanktonic assemblages, respectively, in order to detect toxic Ostreopsis species in Mediterranean Sea. The specificity and sensitivity of the molecular PCR assay were assessed with both plasmidic and genomic DNA of the target genus or species using taxon-specific primers in the presence of background macrophyte DNA. The PCR molecular technique allowed rapid detection of the Ostreopsis cells, even at abundances undetectable within the resolution limit of the microscopy technique. Species-specific identification of Ostreopsis was determined only by PCR-based assay, due to the inherent difficulty of morphological identification in field samples. In the monitoring of the toxic Ostreopsis blooms PCR-based methods proved to be effective tools complementary to microscopy for rapid and specific detection of Ostreopsis and other toxic dinoflagellates in marine coastal environments. 相似文献
89.
Benali Amel Peresan Antonella Varini Elisa Talbi Abdelhak 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(6):775-791
Stochastic Environmental Research and Risk Assessment - An adequate characterization of the temporal features of background seismicity, namely after removal of temporally and spatially clustered... 相似文献
90.
Antonella Bertagnini Alessio Di Roberto Massimo Pompilio 《Bulletin of Volcanology》2011,73(9):1229-1243
The persistent normal activity of Stromboli is occasionally interrupted by sudden and highly energetic explosive events called
Strombolian paroxysms. These phenomena together with landslide-generated tsunamis represent the most hazardous manifestations
of present-day volcanic activity at Stromboli. The most recent paroxysms, on 5 April 2003 and 15 March 2007, have drawn attention
to these energetic events because they significantly threatened inhabitants and tourists. Historical accounts and field evidence
indicate, however, that even larger paroxysms, in terms of volume, dispersal of products and intensity of explosive phenomena,
occurred in the recent past. During these paroxysms incipiently welded spatter deposits mantled the north and south rims of
the Sciara del Fuoco down to low elevations, extending much farther than the similar deposits from recent observed events
(5 April 2003 and 15 March 2007). In order to identify, characterize and discriminate among products of these outstanding
spatter-forming eruptions, more than 50 stratigraphic sections were measured and sampled. Stratigraphic, sedimentological
and radiometric (14C) data indicate that only two paroxysms produced spatter that reached very low elevations and inhabited areas: the first
occurred in the 16th century and the last in AD 1930. Analysis of texture and deposit components reveals that the early phases
of the two eruptions were driven by distinctly different eruptive dynamics. Both identified paroxysms are at least one order
of magnitude greater than any similar event observed by monitoring systems at Stromboli. These two large paroxysms were the
most powerful volcanic events at Stromboli in the last eighteen centuries. 相似文献