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61.
We present some algebraic and numerical simulations of the stable boundary layer. We also discuss the problem of the existence
of a critical Richardson number (Ri), beyond which the turbulence is suppressed. We compare the results of a second-order algebraic model with those of a third-order
numerical model and, to this purpose, numerical simulations of a wind-tunnel flow, which is characterized by various Richardson
numbers, were performed. As far as the second-order model is concerned, solutions, for the Richardson number greater than
any critical value, can be obtained by modifying the time scales of the second-order equation pressure correlation terms in
order to account for a buoyancy damping factor. We show that using a third-order model allows the same results (no critical
Richardson number) to be obtained without modifications to the time scales. It is suggested that the non-locality, accounted
for by the third-order moments, could allow the turbulence to persist also for Ri > 1. 相似文献
62.
Notti Davide Wrzesniak Aleksandra Dematteis Niccolò Lollino Piernicola Fazio Nunzio Luciano Zucca Francesco Giordan Daniele 《Landslides》2021,18(7):2341-2365
Landslides - In November 2016, an extreme rainfall event affected the Ligurian Alps (NW Italy). Consequently, several landslides and debris flows occurred in the upper Tanarello stream basin. In... 相似文献
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64.
Paola Ronchi Daniele Masetti Stefano Tassan Davide Camocino 《Marine and Petroleum Geology》2012,29(1):68-89
The Early Jurassic dolomitized carbonates in the Venetian Alp, represent a surface analogue of the hydrocarbon exploration targets in Adriatic offshore and Po Plain, Italy. Dolomitization affected the carbonate platform of Monte Zugna Formation (Lower Jurassic) and the Neptunian dikes breccia in the pelagic Maiolica Formation (Uppermost Jurassic–Lower Cretaceous) improving the poro-perm characteristics. Petrography, stable isotope, strontium isotope ratio, trace element and fluid inclusion analyses were carried out on samples from the Monte Grappa Anticline, which is the direct analogue for subsurface. The petrographic analyses showed a first pervasive, replacement dolomitization phase (D1) followed by volumetrically less important dolomite cement precipitation phases (D2, D3, DS). The same, quite wide range of oxygen isotope (?9 to ?2‰ V-PDB) is observed in all dolomite types. The δ13C range is in the positive field of marine derived carbonate (from +0.5 to +3.2‰ PDB). The trace element analysis showed a slight enrichment in Fe and Mn contents in the Monte Zugna dolostones with respect the original limestone. The same dolomite precipitation temperature (up to 105 °C Th) was observed in the replacement and cement dolomites, suggesting a unique dolomitization event. This temperature, largely higher than the maximum burial temperature (about 50 °C), supports a hydrothermal origin of the dolomitizing fluids, which had a seawater to brackish composition. The data collected suggest a hydrothermal dolomitization occurring during to the South Alpine thrusting according to the “squeegee model”. The interpretation is consistent with the dolomitization model proposed for similar Jurassic successions in the Central Southern Alps. This study indicates that the deformed foreland and thrust fold belts carbonates in Po Plain and Adriatic offshore are suitable to be dolomitized, and therefore reflect an efficient hydrocarbon exploration play. 相似文献
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66.
Bruno Pavoni Elena Centanni Sara Valcanover Marco Fasolato Silvia Ceccato Davide Tagliapietra 《Marine pollution bulletin》2007,55(10-12):505
Specimens of Nassarius nitidus were collected in seven stations of the Venice Lagoon to assess the levels of tributyltin (TBT) and its metabolites monobutyltin and dibutyltin in the tissues and monitor their effect on organisms, in particular the phenomenon of imposex (superimposition of male sexual characteristics on females). The following values of population indices were found: vas deferens sequence: 1.2 ± 0.7–4.0 ± 0.5; relative penis length: 6–47%. The least impacted station was situated in the northern part of the Lagoon, where females without imposex were found and Butyltin (BuTs) concentrations in the organisms (average sum of BuTs = 43 ± 14 ng Sn g−1 w.) were significantly lower than in the other stations (range of average sum of BuTs: 101 ± 22–217 ± 27 ng Sn g−1 d.w.). Population indices were found to be related to the TBT content in the tissues. In particular VDSI had a significant logarithmic correlation: r = 0.95, n = 8, p < 0.05. 相似文献
67.
Davide Lenaz Vadim S. Kamenetsky Anthony J. Crawford Francesco Princivalle 《Contributions to Mineralogy and Petrology》2000,139(6):748-758
Detrital spinel is a widespread heavy mineral in sandstones from the Maastrichtian–Middle Eocene sedimentary basins in the
SE Alps. Chemistry of detrital spinels from the Claut/Clauzetto and Julian Basins (N Italy and NW Slovenia) is used to constrain
petrological and geochemical affinities and tectonic provenance of the source rocks. In addition, we have analysed melt inclusion
compositions in the detrital volcanic spinels to better constrain the nature of their parental magmas. This is the first study
of melt inclusions in detrital spinels. Two principal compositional groups of detrital spinels are recognised based on their
TiO2 and Fe2+/Fe3+; one derived from peridotites, the other from basaltic volcanics. Peridotitic spinels are more abundant and have TiO2 < 0.2 wt% and high Cr/Cr + Al (40–90), characteristic of suprasubduction zone harzburgites. Significant chemical variations
among volcanic spinels (TiO2 up to 3 wt%, Al2O3 12–44 wt%) suggest multiple sources, with geochemically distinct characteristics, including MORB-type and backarc basin basalts,
subduction-related magmas and tholeiites produced during early continental rifting. Compositions of homogenised melt inclusions
in spinels with TiO2 > 0.2 better distinguish the differences between the compositions of their host spinels and help to further clarify the geodynamic
provenance of extrusive source rocks. Several compositional groups of melt inclusions have been recognised and represent diverse
magmatism of marginal basins, including MORB- and subduction-related geochemical types, as well as magmas characteristic of
early continental rifting. These results, combined with the data on regional ophiolitic complexes and tectonic reconstructions
favour the Internal Dinarides of Yugoslavia as a possible source area for the SE Alps sediments.
Received: 20 January 2000 / Accepted: 25 April 2000 相似文献
68.
Gabriele Ghisellini Davide Lazzati Annalisa Celotti Martin J. Rees 《Monthly notices of the Royal Astronomical Society》2000,316(4):L45-L49
Recently several studies have jointly analysed data from different cosmological probes with the motivation of estimating cosmological parameters. Here we generalize this procedure to allow freedom in the relative weights of various probes. This is done by including in the joint χ 2 function a set of 'hyper-parameters', which are dealt with using Bayesian considerations. The resulting algorithm, which assumes uniform priors on the log of the hyper-parameters, is very simple: instead of minimizing (where is per data set j ) we propose to minimize (where N j is the number of data points per data set j ). We illustrate the method by estimating the Hubble constant H 0 from different sets of recent cosmic microwave background (CMB) experiments (including Saskatoon, Python V, MSAM1, TOCO and Boomerang ). The approach can be generalized for combinations of cosmic probes, and for other priors on the hyper-parameters. 相似文献
69.
Gerardo Herrera Davide Notti Juan Carlos Garc��a-Davalillo Oscar Mora Geraint Cooksley M��nica S��nchez Alain Arnaud Michele Crosetto 《Landslides》2011,8(2):195-206
This paper describes the use of the Stable Point Network technique, a Persistent Scatterer Interferometry SAR technique, for
the analysis of the Portalet landslide area (Central Pyrenees, Spain). For this purpose, different SAR datasets acquired by
ERS-1, ERS-2, ENVISAT and TerraSAR-X satellites have been analysed. The use of different SAR images acquired by satellite
radar sensors operating at different microwave lengths has allowed for a comparative assessment and illustration of the advantages
and disadvantages of these satellites for landslide detection and monitoring. In the introduction, differential interferometry
and the study area are briefly described. Then the specifics of the SPN processing and the results of the different datasets
are described and compared. In Analysis of the results: the Portalet landslide area, the Portalet landslide area is introduced
and the radar displacement measurements are analysed with available geo-information data. Additionally, X-band measurements
are compared with those gathered by a ground-based SAR for a previous project. Finally, the most relevant conclusions of this
work are discussed. 相似文献
70.