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141.
The Italian catalogue contains many earthquakes of moderate to high epicentral intensity which are located in areas of low seismicity and near big cities. Some of them have been inserted in the catalogue after one historical record only. This study investigates many such events in the 1000–1690 time-window showing that a great number of them are fake. Starting by an operational definition of ‘fake quake’, this paper shows the procedures adopted, and the main results which contribute in a significant way to the reassessment of seismicity and seismic hazard. 相似文献
142.
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144.
Theoretical and Applied Climatology - Colombia’s lightning climatology was studied using 16 years of high-resolution data from the Tropical Rainfall Measuring Mission Lightning Imaging Sensor... 相似文献
145.
Rhythmic movements in response to tidal cycles are characteristic of infaunal inhabitant of intertidal soft-bottoms, allowing
them to remain in the area with best living conditions. The effect of bioturbators as modifier of local environmental conditions
and thus of gradients in intertidal habitats, has not been investigated yet. The Atlantic estuarine intertidal areas are dominated
by the burrowing crabChasmagnathus granulatus that generates strong environmental heterogeneity by affecting the physical-chemical characteristics of the sediment. The
comparison between intertidal areas with and without crab shows that sediments in the crab beds remain more humid, softer,
and homogeneous across the intertidal and along the tidal cycle than areas without crabs. The densities of infauna were higher
at high intertidal zones in crab beds than in similar areas without crabs. Infaunal organisms performed vertical movements
into the sediment following the tidal cycle that were always of higher magnitude in habitats without crabs. Infaunal species
tend to spend most of the time buried into the sediment in the crab bed. Migratory shorebirds use the Atlantic estuarine environments
as stopover or wintering sites. They feed (mainly on polychaetes) in the low intertidal zones of both habitats (with and without
crabs), but they also feed in the upper intertidal of the crab bed; polychaete per capita mortality rate is higher in the
upper part of the crab bed. Environmental heterogeneity produced by crab disturbance has an effect on the infaunal behavior,
risk of mortality, and the zonation pattern. This is another example of the ecosystem engineering ability of a burrowing intertidal
species. 相似文献
146.
The taphonomic and archeological implications of massive mortality patterns of guanaco (Lama guanicoe) populations due to winter stress are discussed, considering both local and regional scales. The presentation has its focus in the Lake Cardiel basin, Southern Patagonia, Argentina. Winter stress is not an unusual event in Patagonian ecosystems and it produces a seasonal and predictable output: a huge number of dead guanacos in certain loci.Five faunal assemblages formed in 2000 are discussed, three in rock shelters and two at open-air settings, considering guanaco individuals/bone preservation, age and sex structure, death positions, degree of interment, carnivore damages, trampling marks, and the association between guanaco individuals/bones and archeological material (mainly lithic artifacts). Conditions exist for the commingling of naturally formed guanaco bone assemblages and archeological materials. The taphonomic signature of this mortality pattern is analysed, and criteria developed that allow identification of the potential mixture between archeological material and modern guanaco bones. From an archeological point of view, the potential scavenging opportunities brought by these guanaco mortality events to hunter-gatherer populations are explored.In sum, the results of this study are twofold. First, it brings new data on the regional taphonomy of guanacos and its implications for the archeological record. Second, it invites consideration of these mass mortality events in the context of strategies employed by hunter-gatherer populations to cope with their environment. 相似文献
147.
Federico?OteroEmail author Federico?Norte Diego?Araneo 《Theoretical and Applied Climatology》2018,131(1-2):213-225
The aim of this work is to obtain an index for predicting the probability of occurrence of zonda event at surface level from sounding data at Mendoza city, Argentine. To accomplish this goal, surface zonda wind events were previously found with an objective classification method (OCM) only considering the surface station values. Once obtained the dates and the onset time of each event, the prior closest sounding for each event was taken to realize a principal component analysis (PCA) that is used to identify the leading patterns of the vertical structure of the atmosphere previously to a zonda wind event. These components were used to construct the index model. For the PCA an entry matrix of temperature (T) and dew point temperature (Td) anomalies for the standard levels between 850 and 300 hPa was build. The analysis yielded six significant components with a 94 % of the variance explained and the leading patterns of favorable weather conditions for the development of the phenomenon were obtained. A zonda/non-zonda indicator c can be estimated by a logistic multiple regressions depending on the PCA component loadings, determining a zonda probability index \( \widehat{c} \) calculable from T and Td profiles and it depends on the climatological features of the region. The index showed 74.7 % efficiency. The same analysis was performed by adding surface values of T and Td from Mendoza Aero station increasing the index efficiency to 87.8 %. The results revealed four significantly correlated PCs with a major improvement in differentiating zonda cases and a reducing of the uncertainty interval. 相似文献
148.
Diego Vicinanza Iván Cáceres Mariano Buccino Xavier Gironella Mario Calabrese 《Coastal Engineering》2009,56(11-12):1173-1185
In recent years the hydraulic performance of low-crested structures has been widely studied both theoretically and through experimental analyses, but only a few studies have been focused on the combined diffraction-overtopping effects on wave transmission and induced wave currents.In this paper hydraulic model tests conducted at the 3D wave basin of Delft University of Technology (Cáceres et al., 2008) were used to obtain and discuss two simple methods for predicting the wave height at the lee of a single detached breakwater of finite length and the related current regime. For the first time diffraction effects are expressly accounted for. The agreement with experimental data is encouraging.The main objective of the paper is to aid engineers in the first stage of the design process, when using a mathematical model could be unnecessarily excessive. 相似文献
149.
Philip?SchütteEmail author Massimo?Chiaradia Fernando?Barra Diego?Villagómez Bernardo?Beate 《Mineralium Deposita》2012,47(4):383-410
Mineralization and alteration events at ten Miocene porphyry Cu and porphyry-related epithermal mineral deposits in southern,
central, and northern Ecuador were dated by means of molybdenite Re-Os, biotite and alunite 40Ar/39Ar, and titanite U-Pb geochronology. Most of these hydrothermal events show a spatio-temporal correlation with porphyry intrusion
emplacement as constrained by zircon U-Pb ages. The total age range for these events spans the 23.5–6.1 Ma period, without
displaying systematic along- or across-arc age distribution trends. While epithermal deposits tend to be spatially associated
with volcanic rocks of a similar age, porphyry Cu deposits in Ecuador are frequently spatially associated with deeper-seated
basement units and batholith-scale precursor intrusive systems assembled over ≥5 m.y. time periods. In most cases, formation
of the porphyry Cu deposits is related to the youngest magmatic (-hydrothermal) event in a given area, postdating batholith
construction at a regional scale. The majority of Miocene deposits occurs in southern Ecuador where areally extensive, post-mineralization
(late Miocene to recent) volcanic sequences with the potential to conceal mineralization at depth are lacking. Only few Miocene
deposits occur in northern-central Ecuador, where they mainly crop out in the Western Cordillera, west of the productive present-day
volcanic arc. The surface distribution of post-mineralization arc volcanism reflects along-arc variations in subducting slab
geometry. Porphyry Cu and epithermal deposits in Ecuador define a Miocene metallogenic belt broadly continuous with its coeval
counterpart in northern-central Peru. Although both belt segments were formed in an overall similar tectonomagmatic and metallogenic
setting, their respective metal endowments differ significantly. 相似文献
150.
Stochastic methods based on time-series modeling combined with geostatistics can be useful tools to describe the variability of water-table levels in time and space and to account for uncertainty. Monitoring water-level networks can give information about the dynamic of the aquifer domain in both dimensions. Time-series modeling is an elegant way to treat monitoring data without the complexity of physical mechanistic models. Time-series model predictions can be interpolated spatially, with the spatial differences in water-table dynamics determined by the spatial variation in the system properties and the temporal variation driven by the dynamics of the inputs into the system. An integration of stochastic methods is presented, based on time-series modeling and geostatistics as a framework to predict water levels for decision making in groundwater management and land-use planning. The methodology is applied in a case study in a Guarani Aquifer System (GAS) outcrop area located in the southeastern part of Brazil. Communication of results in a clear and understandable form, via simulated scenarios, is discussed as an alternative, when translating scientific knowledge into applications of stochastic hydrogeology in large aquifers with limited monitoring network coverage like the GAS. 相似文献