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411.
The use of spring water as a drinking, therapeutic, and ornamental resource has historical origins that date back to the Romans. The most ancient regulations on mineral waters had been enacted in Italy long before the union (1870). 相似文献
412.
Twenty one ichnogenera and 30 ichnospecies are recognized in the Late Campanian – Maastrichtian Monte Antola Formation of Italy, most of them for the first time. They belong to a specific mixture of the Nereites and Ophiomorpha rudis ichnosubfacies of the Nereites ichnofacies. Composition and abundance of trace fossils vary from outcrop to outcrop. Chondrites intricatus, Ch. targionii, Nereites irregularis, Cladichnus fischeri and Trichichnus linearis are most common. Chondrites patulus, Ophiomorpha recta and “Spirophycus” bicornis trace fossils are less common in outcrops, and the other trace fossils are rare or very rare. Generally, ichnogeneric diversity in Cretaceous–Cainozoic calcareous and mixed siliciclastic-calcareous flysch deposits is distinctly lower than in siliciclastic flysch. Significantly, the foremost pre-depositional forms are distinctly rare, probably due to preservational and depositional factors. 相似文献
413.
The numerical block-model of the lithosphere dynamics is used to simulate seismicity in Italy and its surroundings, based
on the available structural and geodynamics information. The purpose of the study is to understand which are the tectonic
processes that control the main features of the observed seismicity and the kinematics of the region. The influence of the
rheology of the fault systems is studied as well. The model we use differs from other modeling approaches in that it simulates
earthquakes and hence it possibly relates to seismicity and geodynamics. The model provides an effective capability to include
the set of documented constraints supplied by widely available earthquake catalogs. This is done by means of the comparison
of the GR relation, of the focal mechanisms and of the space distribution for observed and computed seismicity. The region
is modeled as a system of perfectly rigid blocks, separated by infinitely thin fault planes, in viscoelastic interaction between
themselves and with the underlying medium. The movement of the boundary blocks and of the underlying medium determines the
motion of the blocks. The synthetic seismicity obtained with the defined block-model is similar to the observed one for the
most seismically active areas. A linear frequency-magnitude (FM) relation (Gutenberg-Richter law) is obtained for synthetic
earthquakes; the slope (b-value) of the FM plot appears larger for the synthetic seismicity than for the observed one. Nevertheless, the b-value is essentially larger in northern and central Italy than that in southern Italy, both in the model and in the observations.
The analysis of the source mechanisms of the synthetic earthquakes shows a good agreement with the observations. In the model
normal faulting is typical for the Apennines, the eastern edge of Sicily and the Calabrian arc, while reverse faulting takes
place at the northwestern boundary of the Adriatic Sea, in the southern Alps and along the eastern edge of the Adria, along
the Dinarides. The model correctly reproduces the extension zone along the Apennines and the contraction zone along the northwestern
boundary of the Adriatic Sea; the counter-clockwise rotation of the Adria is mimed. The resulting movements of the blocks
are in overall agreement with GPS (Global Positioning System) observations. The results of the modeling experiments suggest
that the main features of dynamics and seismicity in the central Mediterranean region cannot be satisfactorily explained as
a consequence of Africa and Eurasia convergence only; the passive subduction in the Calabrian arc and the different rheology
of faults are essential as well. 相似文献
414.
During explosive eruptions the deposition of fine-grained volcanic ash fallout reduces soil permeability, favouring runoff
of meteoric water and thus increasing the occurrence of catastrophic floods. A fully dynamic, two-dimensional model was used
to simulate flooding scenarios in the Vesuvian area following an explosive volcanic eruption. The highest risk occurs in the
catchment area of the Acerra-Nola Plain N and NE of Vesuvius. This plain has a population of 70,000 living in low-lying areas.
This catchment area is vulnerable to ash fall because it lies downwind of the dominant synoptic circulation and it lacks a
natural outflow toward the sea. Our numerical simulations predict dangerous scenarios, even in quiescent periods, during extreme
rain events (return periods of 200 years have been considered), and a significant increase in the extent of the flooded areas
due to renewed volcanic activity. Based on these simulations a hazard zonation has been proposed.
Editorial responsibility: A Woods 相似文献
415.
The diversity of epiphytic lichens and mercury concentrations in lichen samples were measured to monitor the release of airborne pollutants from the industrial exploitation of geothermal resources in the Mt. Amiata area (Italy). The lichen biodiversity showed a general condition of moderate environmental alteration around the geothermal power plants, contrasting with the low environmental alteration of the remaining sites investigated. According to the accumulated Hg in lichen thalli, it was possible to estimate mean Hg and H2S concentrations in the air, which resulted in very good agreement with values measured instrumentally. Based on these data and the correlation between lichen diversity values and Hg concentrations in lichens, it was possible to calculate the threshold of 8 μg/m3 H2S as responsible for the worsening from low to moderate environmental alteration according to the biodiversity of epiphytic lichens, and to infer that around geothermal power plants, although not toxic to humans, H2S concentrations are such to alter the nasal quality of the air. Based on the growth rate of X. parietina, it was possible to convert Hg concentrations into estimates of average Hg deposition rates, which showed fluxes of the order of 65–100 mg/ha/y, indicating a dispersions factor of about 104 for the Hg emitted from the geothermal power plants. 相似文献
416.
Massimo Rinaldi 《地球表面变化过程与地形》2003,28(6):587-608
Drastic channel adjustments have affected the main alluvial rivers of Tuscany (central Italy) during the 20th century. Bed‐level adjustments were identified both by comparing available topographic longitudinal profiles of different years and through field observations. Changes in channel width were investigated by comparing available aerial photographs (1954 and 1993–98). Bed incision represents the dominant type of vertical adjustment, and is generalized along all the fluvial systems investigated. The Arno River system is the most affected by bed‐level lowering (up to 9 m), whereas lower incision (generally less than 2 m) is observed along the rivers of the southern part of the region. Human disturbances appear to be the dominant factors of adjustments: the main phase of vertical change occurred during the period 1945–80, in concomitance with the phase of maximum sediment mining activity at the regional scale. The second dominant type of adjustment that involved most of the rivers in the region consists of a narrowing of the active channel. Based on measurements of channel width conducted on aerial photographs, 38% of the reaches analysed experienced a narrowing greater than 50% of the initial channel width. The largest values of channel narrowing were observed along initially braided or sinuous with alternate bars morphologies in the southern portion of the region. A regional scheme of channel adjustments is derived, based on initial channel morphology and on the amounts of incision and narrowing. Different styles of channel adjustments are described. Rivers that were originally sinuous with alternate bars to braided generally became adjusted by a moderate incision and a moderate to intense narrowing; in contrast, sinuous‐meandering channels mainly adjusted vertically, with a minor amount of narrowing. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
417.
Giacomo D''Amato Avanzi Roberto Giannecchini Alberto Puccinelli 《Engineering Geology》2004,73(3-4):215-228
On June 19, 1996, an extremely heavy rainstorm hit a restricted area in the Apuan Alps (northwestern Tuscany, Italy). Its max intensity concentrated over an area of about 150 km2 astride the Apuan chain, where 474 mm was recorded in about 12 h (21% of the mean annual precipitation, with an intensity up to 158 mm/h). The storm caused floods and hundreds of landslides and debris flows, which produced huge damage (hundreds of millions of Euros), partially destroyed villages and killed 14 people. This paper reports the results obtained from a detailed field survey and aerial view interpretation. In the most severely involved area, 647 main landslides were investigated, mapped and related to the geologic, geomorphic and vegetational factors of the source areas. This was in order to define the influence of these factors and contribute to an evaluation of the landslide hazard in the study area. An assessment was also made of the total area and volume of material mobilised by landsliding. The study area, about 46 km2 wide, includes three typically mountainous basins, characterised by narrow, deep cut valleys and steep slopes, where many rock types outcrop. Most of the landslides were shallow and linear, referable to complex, earth and debris translational slide, which quickly developed into flow (soil slip–debris flow). Usually, they involved colluvium and started in hollows underlain by metamorphic rock (metasandstone and phyllite), often dipping downslope. Therefore, bedrock lithology and impermeability appeared to be important factors in the localisation of the landslide phenomena. The investigation of the geomorphic and land use features in the source areas also frequently highlighted a rectilinear profile of the slope, a high slope gradient (31–45°) and dense chestnut wood cover. In the area, about 985,000 m2 (2.1% of 46 km2) was affected by landsliding and about 700,000 m2 of this area was covered by chestnut forest. The landslides removed about 7000 trees. The volume of mobilised material was about 1,360,000 m3; about 220,000 m3 remained on the slopes, while the rest poured into the streams. In addition, about 945,000 m3 was mobilised by the torrential erosion in the riverbeds. 相似文献
418.
Geochemistry of heavily exploited aquifers in the Emilia-Romagna region (Po Valley, northern Italy) 总被引:1,自引:0,他引:1
More than 5 800 chemical analyses on water samples collected during 1987–1995 from 528 monitoring wells located in the southernmost
part of the Po Valley (Emilia-Romagna region, northern Italy), one of the most urbanized, industrialized and agriculturally
developed areas of Italy, have been processed. The analysis of data showed that: (1) waters are discharging from both confined
and unconfined aquifers; (2) the water in the unconfined aquifer(s) is Ca(Mg)-HCO3 in composition while confined ones are Na-Cl and/or Na-(HCO3); (3) both confined and unconfined aquifer samples have δ18O and δD isotopic values of meteoric signature; (4) waters from both the aquifers are at least 40 years old; (5) the pumping
rate has caused subsidence, particularly where the aquifer(s) is (are) unconfined; (6) the unconfined aquifer(s) is exposed
to the risk of NO3 pollution; (7) considering the present "pressure" (i.e. pumping rate) on this natural environment by human activity, care
must be taken in the future to preserve this "strategic" resource.
Received: 27 October 1997 · Accepted: 12 March 1998 相似文献
419.
Proposal of a method to define areas of landslide hazard and application to an area of the Dolomites, Italy 总被引:1,自引:0,他引:1
A numerical–cartographical method has been developed to create landslide hazard maps. This method allows the assigning of a rating to the various parameters which contribute to landslides. The parameters considered are: (1) erodibility and degradability of the rocks and Quaternary deposits; (2) permeability of the ground to identify areas prone to hydraulic overpressure; (3) the geometric ratio between discontinuities and slope, and thickness of Quaternary deposits; (4) angle of the slopes; and (5) land use. A thematic map is constructed for each factor considered which defines different areas through ratings, after which all the thematic maps are overlaid and the ratings added up (or multiplied). The map which is thus obtained is reclassified in order to create the final map of landslide hazard. This method, which has already been tested in various areas, has produced excellent results in this case too, allowing a map to be constructed which corresponds to the actual instability problems. 相似文献
420.
Fiumara is a kind of gravel-bed river, very steep and short, which flow through the southern Italy mountain chains, in Sicilia and Calabria regions. These streams drain mountain areas only, and are subject to a Mediterranean climate. They have a great transport and erosion capacity because of their flow regime, dominated by episodic flash floods alternated with long periods of inactivity during which their beds become completely dry. During this last century, the natural equilibrium of these particular alluvial environments has undergone notable modifications caused also by human activities. The effects of such works are investigated in terms of river dynamics, and some local examples are reported and discussed; some suggestions are made for recovery measures too. 相似文献