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81.
Christina L. Richards Susan N. White Mary Anne McGuire Steven J. Franks Lisa A. Donovan Rodney Mauricio 《Estuaries and Coasts》2010,33(4):840-852
Evolutionary ecologists have long been intrigued by the fact that many plant species can inhabit a broad range of environmental
conditions and that plants often exhibit dramatic differences in phenotype across environmental gradients. We investigated
responses to salinity treatments in the salt marsh plant Borrichia frutescens to determine if the species is responding to variation in edaphic salt content through phenotypic plasticity or specialized
trait response. We grew seedlings from fruits collected in high- and low-salt microhabitats, assigned seedlings to high- and
low-salt treatments in a greenhouse, and measured traits related to salt tolerance. All traits were highly plastic in response
to salinity. Plants from the two microhabitats did not differ in trait means or respond differently to the treatments. These
results suggest that environmental differences between the two microhabitats are not creating genotypes adapted to high and
low salt levels. In addition, despite evidence for variation in allozyme markers in this population, there was no significant
genotypic variation (family effect) in any of the trait means measured across microhabitats. There was variation in plasticity
for only leaf Na and leaf B concentration. The high degree of plasticity for all traits and the lack of differences among
microhabitats across the salinity gradient suggest plasticity in many traits may be fixed for this species. 相似文献
82.
Segura Hans Espinoza Jhan Carlo Junquas Clementine Lebel Thierry Vuille Mathias Garreaud Rene 《Climate Dynamics》2020,54(5):2613-2631
Climate Dynamics - Analyzing December–February (DJF) precipitation in the southern tropical Andes—STA ($$12^{\circ }\,\hbox {S}$$–$$20^{\circ }\,\hbox {S}$$; > 3000... 相似文献
83.
Oscar Link Luis M. Brox‐Escudero John Gonzlez Mauricio Aguayo Fernando Torrejn Gonzalo Montalva Miguel . Eguibar‐Galn 《水文研究》2019,33(25):3169-3183
Comprehensive flood risk assessment requires enhanced understanding of the coevolution of the river and its floodplain occupation. Paleoflood analysis to determine flood prone areas in combination with numerical simulations to estimate flood hazard and a historical analysis of urban development to consider the evolution of exposure to floods is a possible way forward. The well‐documented 2006 extreme flood in the Biobío River system and the impacted metropolitan area of Concepción, Chile (~1 million inhabitants) was used as a complex scenario to test the reliability of the proposed method. Results showed that flood prone areas determined with hydro‐geomorphological methods are consistent with those computed with numerical models based on detailed digital elevation models. The flood generation via superficial flow pathways resulting in inundated areas could explain that rivers tend to reactivate paleochannels in extreme conditions. Urban development progressively increased the city's exposure to floods from 0 ha in 1,751 to 1,363 ha in 2006 evidencing a lack of appropriate flood risk management. The 100‐year peak discharge resulted in a high flood risk for about 5% of the total urbanized area of Concepción, and higher discharges are likely to reactivate a paleochannel that crosses the current city centre. We conclude that the proposed paleo hydro‐geomorphology, hydraulic, and urban planning multimethod approach is a necessary tool to enhance understanding of flood risk in complex scenarios to improve flood risk management. 相似文献
84.
Autoregressive modeling is used to estimate the spectrum of aliased data. A region of spectral support is determined by identifying the location of peaks in the estimated spatial spectrum of the data. This information is used to pose a Fourier reconstruction problem that inverts for a few dominant wavenumbers that are required to model the data. Synthetic and real data examples are used to illustrate the method. In particular, we show that the proposed method can accurately reconstruct aliased data and data with gaps. 相似文献
85.
Mauricio da Rocha Fragoso Gabriel Vieira de Carvalho Felipe Lobo Mendes Soares Daiane Gracieli Faller Luiz Paulo de Freitas Assad Raquel Toste Lívia Maria Barbosa Sancho Elisa Nóbrega Passos Carina Stefoni Böck Bruna Reis Luiz Landau Hernan G. Arango Andrew M. Moore 《Ocean Dynamics》2016,66(3):419-434
86.
Mauricio Jonas Ferreira Amauri Pereira de Oliveira Jacyra Soares Georgia Codato Eduardo Wilde Bárbaro Jo?o Francisco Escobedo 《Theoretical and Applied Climatology》2012,107(1-2):229-246
The main goal of this work is to describe the diurnal and seasonal variations of the radiation balance components at the surface in the city of S?o Paulo based on observations carried out during 2004. Monthly average hourly values indicate that the amplitudes of the diurnal cycles of net radiation (Q*), downwelling and upwelling shortwave radiation (SWDW, SWUP), and longwave radiations (LWDW, LWUP) in February were, respectively, 37%, 14%, 19%, 11%, and 5% larger than they were in August. The monthly average daily values indicate a variation of 60% for Q*, with a minimum in June and a maximum in December; 45% for SWDW, with a minimum in May and a maximum in September; 50% for SWUP, with a minimum in June and a maximum in September; 13% for LWDW, with a minimum in July and a maximum in January; and 9% for LWUP, with a minimum in July and a maximum in February. It was verified that the atmospheric broadband transmissivity varied from 0.36 to 0.57; the effective albedo of the surface varied from 0.08 to 0.10; and the atmospheric effective emissivity varied from 0.79 to 0.92. The surface effective emissivity remained approximately constant and equal to 0.96. The albedo and surface effective emissivity for S?o Paulo agreed with those reported for urban areas in Europe and North America cities. This indicates that material and geometric effects on albedo and surface emissivity in S?o Paulo are similar to ones observed in typical middle latitudes cities. On the other hand, it was found that S?o Paulo city induces an urban heat island with daytime maximum intensity varying from 2.6°C in July (16:00 LT) to 5.5°C in September (15:00 LT). The analysis of the radiometric properties carried out here indicate that this daytime maximum is a primary response to the seasonal variation of daily values of net solar radiation at the surface. 相似文献
87.
The glacial morphology of southern South American presents invaluable evidence to reconstruct former glacier behaviour and its relation to climate and environmental changes. However, there are still spatial and temporal gaps in the reconstruction of the Holocene Patagonian glacial landscape. Here we present the first geomorphological record for the Sierra Baguales Mountain Range(SBMR), forming the eastern foothills of the Southern Patagonian Andes 200 km from the Pacific coast. This area is topographically isolated from the Southern Patagonian Ice Field(SPIF), and is affected by the Westerly Winds. The study area shows evidence of ice sheet and alpine glaciations related to Andean uplift,which caused a marked climatic contrast between its western and eastern flanks since the Last Glacial Maximum(LGM). The regional rock mass strength and precipitation gradient acted as a controlling factor in the glacial cirque distribution and sizes, as well as in the development of glaciation types. We report new radiocarbon dates associated with warm/dry to cold/wet climatic changes during the middle Holocene, when former small alpine glaciers were located in the uppermost section of the SBMR basins, and eventually converged to form a small ice field or a composite valley glacier at lower elevations.This can be explained by an estimated regional temperature drop of 3.8°C±0.8°C, based on a 585±26m Equilibrium Line Altitude(ELA) descent, inferred by geomorphological evidence and the Accumulation Area Ratio(AAR), in addition to a free-air adiabatic lapse rate. Subsequently, the glaciers receded due to climatic factors including a rise in temperature, as well as non-climatic factors, mainly the glacier bedrock topography. 相似文献
88.
This paper examines the spatial dynamics of urbanism in Rio de Janeiro during the early nineteenth century. Conventional narratives of modernisation fail to capture the complexities of this moment, between 1808 and 1821, when the city replaced Lisbon as the capital of the Portuguese empire. The position of colony and metropolis were inverted, Portuguese absolutism was bolstered by British liberalism, and a market-economy arose alongside the expansion of slavery. As the newly-created imperial capital, Rio felt the effects of these various transformations: the physical boundaries of the city rapidly expanded, its economy diversified and the cultural life of the city was re-shaped. Our aim in this paper is to understand this particular moment of urban transformation as a product of the intersection of global networks of trade, slavery and industrial capitalism. Rather than depicting the historical geography of the city as a passive space for European conquest and expansion, we consider the extent to which its urban dynamics were shaped by a distinct local geography of globalisation. In particular, we examine the interrelated spatialities that are part and parcel of the modernising process. 相似文献
89.
Vyacheslav M. Zobin Carlos Navarro Gabriel Reyes-Dávila Justo Orozco Mauricio Bretón Armando Tellez Gabriel Reyes-Alfaro Homero Vázquez 《Geophysical Journal International》2006,167(1):467-478
A methodology is proposed for the quantification of volcanic explosions based on three parameters derived from broad-band seismic signals: the counter force of the eruption F , the power of the explosion P and the duration of the upward movement of the gas slug in the conduit to the free surface of magma, D . This methodology was applied to the 2004–2005 sequence of explosions at Volcán de Colima, Mexico. The broad-band records of more than 100 explosive events were obtained at a distance of 4 km from the crater. We determined the counter force of the eruption by modelling the low-frequency impulse of the seismic records of 66 volcanic explosions and estimated the power of 116 explosions from the spectra of the high-frequency impulse. The power of Colima explosions spans five orders of magnitude; the counter force spans four orders of magnitude. We show that the power of a volcanic explosion is proportional to the counter force of the eruption. These parameters may be used for the elaboration of a scale of volcanic explosions. 相似文献
90.