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81.
Benthic Community and Sediment Types: A Structural Analysis 总被引:2,自引:0,他引:2
Eugenio Fresi Maria Cristina Gambi Silvano Focardi Roberto Bargagli Franco Baldi Lucia Falciai 《Marine Ecology》1983,4(2):101-121
Abstract. The distribution of the macrobenthic community, in relation to various physical and chemical characteristics of the sediment, was studied along the coast of Southern Tuscany (Central Tyrrhenian) in an area under the influence of the Ombrone River outflow.
The zonation of the benthos was found to be primarily under the control of a gradient of water movement, as is reflected by variations in the sediment structure from the coast to the open sea. This correlation is somehow influenced by secondary gradients such as the degree of mixing of the sediment and the deposition of terrigenous materials along the river plume. 相似文献
The zonation of the benthos was found to be primarily under the control of a gradient of water movement, as is reflected by variations in the sediment structure from the coast to the open sea. This correlation is somehow influenced by secondary gradients such as the degree of mixing of the sediment and the deposition of terrigenous materials along the river plume. 相似文献
82.
Rita Colognola Pietro Masturzo Giovanni Fulvio Russo Mlchele Scardi Daniele Vlnci Eugenio Fresi 《Marine Ecology》1986,7(3):265-285
Abstract. Two forms of Rissoa auriscalpium were found in Posidonia oceanica beds around the Island of Ischia (Gulf of Naples). In order to investigate their taxonomical value and to quantify the discriminating features found, the radular, conchometric, genetic, and ecological features of the two forms were analyzed. Ecological observations showed that the distribution of the two forms is strongly correlated with hydrodynamic factors. 相似文献
83.
Wang Liang Zhang Xue Zaniboni Filippo Oñate Eugenio Tinti Stefano 《Mathematical Geosciences》2021,53(1):81-103
Mathematical Geosciences - Notwithstanding its complexity in terms of numerical implementation and limitations in coping with problems involving extreme deformation, the finite element method (FEM)... 相似文献
84.
At Mt. Etna volcano, the emission of plagioclase megacryst-bearing lavas, known locally as “cicirara”, has occurred rarely
and generally in association with unusual volcanological phenomena. In this work, we interpret the magma chamber processes
and the structural features of the plumbing system that led to the production of these peculiar volcanic rocks, based on a
detailed study of plagioclase megacrysts, including their oscillatory zoning, sieve textures, and fluid inclusions. Patchy
zoning suggests limited ascent in the deep levels of the plumbing system, based on the plagioclase nucleation threshold and
the volatile saturation depth. At intermediate, water-undersaturated levels of the plumbing system ascent is faster, as indicated
by crystals with coarse sieve textures. Storage at shallow, water-saturated levels (less than 6 km deep) is associated with
oscillatory zoning with very small changes in An. Slightly larger An variations coupled with different wavelengths provide
evidence of convection of crystals across distinct zones of the chamber. Stripes of melt inclusions formed at steps of magma
ascent and volatile loss, whereas layers of fluid inclusions may be related to episodes of volatile flushing into the magma
chamber. In contrast, strongly sieve-textured envelopes with An increase and constant FeO may be related to mixing with more
volatile-rich magmas of similar composition. We interpret the repeated occurrence of “cicirara” lavas as evidence that the
shallow portion of the plumbing system underwent a progressive coalescence of a complex network of dykes and sills in response
to increasing rates of magma supply from depth. Major magma withdrawals from this larger reservoir may be linked to episodes
of summit instability associated with major caldera collapses. 相似文献
85.
The Karhunen–Loéve (K–L) method is used to interpret dynamic response data obtained from shaking table and pseudodynamic tests conducted on civil engineering structures subjected to earthquake loading. It is shown how the K–L method can be used to monitor on‐line, or a posteriori, the structural response of non‐linear dynamical systems. Results from these analyses make it possible to quantitatively verify the number and participation factors of non‐linear modes and how they correspond to physical behaviour of the structure. Comments are made regarding the use of this technique in various fields including numerical calculations, experiments and control. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
86.
Coupled use of carbon isotopes and noble gas isotopes in the Potiguar basin (Brazil): Fluids migration and mantle influence 总被引:1,自引:0,他引:1
We used the carbon isotope ratios of hydrocarbons and CO2, and the proportions of noble gas isotopes of associated gases from several geological provinces of the Potiguar Basin (Brazil) for gas/source rock correlation, and to determine maturity, post-genetic processes (migration, leakage, biodegradation), and to assess the possible interactions between hydrocarbons and surrounding waters. Barriers of permeability at the basin scale, the amount of water interacting with the accumulated hydrocarbons, proportion of meteoric water, and contamination of the fluids by the mantle were quantified for the distinct petroleum systems defined in this basin. 相似文献
87.
Late Cenozoic brittle deformation in the Southern Patagonian Andes: Record of plate coupling/decoupling during variable subduction? 下载免费PDF全文
Vanesa Barberón Christian Sue Matías Ghiglione Gonzalo Ronda Eugenio Aragón 《地学学报》2018,30(4):296-309
The Andes of southern Patagonia experienced a Miocene shift towards faster and higher angle subduction followed by the approach and collision of the Chile oceanic ridge. We present a kinematic study characterizing palaeostress fields computed from brittle tectonics to better constrain upper crustal deformation during this complex scenario. Although previous studies already suggested variable kinematics, it is striking that in a long‐lasting subduction environment, the computed palaeostress tensors are mostly strike‐slip (55%), while 35% are extensional, and only 10% compressive which are concentrated along a main frontal thrust. Cross‐cutting relationships and synsedimentary deformation indicate that a long‐lived strike‐slip regime was punctuated by a lower Miocene extensional event in the foreland before the main compressional event. The results are discussed in contrasting geodynamic models of plate coupling/decoupling versus direction and rate of convergence of the subducting plate, to explain the main mechanisms that control back‐arc deformation. 相似文献
88.
Maria Antonia Brovelli Mattia Crespi Francesca Fratarcangeli Francesca Giannone Eugenio Realini 《ISPRS Journal of Photogrammetry and Remote Sensing》2008,63(4):427-440
Interest in high-resolution satellite imagery (HRSI) is spreading in several application fields, at both scientific and commercial levels. Fundamental and critical goals for the geometric use of this kind of imagery are their orientation and orthorectification, processes able to georeference the imagery and correct the geometric deformations they undergo during acquisition. In order to exploit the actual potentialities of orthorectified imagery in Geomatics applications, the definition of a methodology to assess the spatial accuracy achievable from oriented imagery is a crucial topic.In this paper we want to propose a new method for accuracy assessment based on the Leave-One-Out Cross-Validation (LOOCV), a model validation method already applied in different fields such as machine learning, bioinformatics and generally in any other field requiring an evaluation of the performance of a learning algorithm (e.g. in geostatistics), but never applied to HRSI orientation accuracy assessment.The proposed method exhibits interesting features which are able to overcome the most remarkable drawbacks involved by the commonly used method (Hold-Out Validation — HOV), based on the partitioning of the known ground points in two sets: the first is used in the orientation–orthorectification model (GCPs — Ground Control Points) and the second is used to validate the model itself (CPs — Check Points). In fact the HOV is generally not reliable and it is not applicable when a low number of ground points is available.To test the proposed method we implemented a new routine that performs the LOOCV in the software SISAR, developed by the Geodesy and Geomatics Team at the Sapienza University of Rome to perform the rigorous orientation of HRSI; this routine was tested on some EROS-A and QuickBird images. Moreover, these images were also oriented using the world recognized commercial software OrthoEngine v. 10 (included in the Geomatica suite by PCI), manually performing the LOOCV since only the HOV is implemented.The software comparison guaranteed about the overall correctness and good performances of the SISAR model, whereas the results showed the good features of the LOOCV method. 相似文献
89.
Ali?Ben Dhiab Mehdi?Ben Mimoun Jose?OterosEmail author Herminia?Garcia-Mozo Eugenio?Domínguez-Vilches Carmen?Galán Mounir?Abichou Monji?Msallem 《Theoretical and Applied Climatology》2017,128(3-4):541-549
Tunisia is the world’s second largest olive oil-producing region after the European Union. This paper reports on the use of models to forecast local olive crops, using data for Tunisia’s five main olive-producing areas: Mornag, Jemmel, Menzel Mhiri, Chaal, and Zarzis. Airborne pollen counts were monitored over the period 1993–2011 using a Cour trap. Forecasting models were constructed using agricultural data (harvest size in tonnes of fruit/year) and data for several weather-related and phenoclimatic variables (rainfall, humidity, temperature, Growing Degree Days, and Chilling). Analysis of these data revealed that the amount of airborne pollen emitted over the pollen season as a whole (i.e., the Pollen Index) was the variable most influencing harvest size. Findings for all local models also indicated that the amount, timing, and distribution of rainfall (except during blooming) had a positive impact on final olive harvests. Air temperature also influenced final crop yield in three study provinces (Menzel Mhiri, Chaal, and Zarzis), but with varying consequences: in the model constructed for Chaal, cumulative maximum temperature from budbreak to start of flowering contributed positively to yield; in the Menzel Mhiri model, cumulative average temperatures during fruit development had a positive impact on output; in Zarzis, by contrast, cumulative maximum temperature during the period prior to flowering negatively influenced final crop yield. Data for agricultural and phenoclimatic variables can be used to construct valid models to predict annual variability in local olive-crop yields; here, models displayed an accuracy of 98, 93, 92, 91, and 88 % for Zarzis, Mornag, Jemmel, Chaal, and Menzel Mhiri, respectively. 相似文献
90.
Abstract Spatial and temporal vegetation contrasts between the nations of Haiti and the Dominican are analyzed using NDVI data derived from 30m resolution Landsat imagery and 8km resolution AVHRR imagery from the NOAA / NASA Pathfinder database. Analysis of vegetation dynamics in the Hispaniola border region indicates denser vegetation cover and a stronger correlation between elevation, slope, and NDVI on the Dominican side of the frontier. Temporal patterns of NDVI dynamics along the frontier suggest that changes in biomass are both more homogeneous and more extreme on the Haitian side. Analysis of 17 years of 8km resolution AVHRR imagery for the entire island of Hispaniola reveals consistently higher NDVI values for the Dominican Republic and a distinct intra‐annual pattern of mean monthly NDVI deviations that have important implications for future studies of vegetation dynamics in the region. 相似文献