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121.
Heliana Teixeira João Magalhães Neto Joana Patrício Helena Veríssimo Rute Pinto Fuensanta Salas João Carlos Marques 《Marine pollution bulletin》2009,58(10):1477-1486
Assessing the health of ecosystems has become a focal point among researchers worldwide. Recently, the European Water Framework Directive intensified the development of approaches to assess ecosystems’ ecological quality. The Benthic Assessment Tool (BAT) is a multimetric approach to evaluate condition of subtidal soft bottom macroinvertebrates of coastal and transitional waters. The effects of anthropogenic disturbances on benthic macroinvertebrate communities, from 1990 to 2006, allowed testing BAT performance in Mondego estuary (Portugal). The method was able to detect decrease on ecological quality, induced essentially by eutrophication and physical disturbances, and follow communities’ subsequent recovery. It evidenced, nevertheless, some limitations associated with the unstable nature of estuaries. The ecological classification of key species in the community and the balance expected between ecological groups of estuarine communities had great influence in the final ecological assessment. Shortcomings of the method were discussed in the light of its suitability for assessing transitional waters’ condition. 相似文献
122.
Spatial distribution of heavy metals in surficial sediments from Guanabara Bay: Rio de Janeiro, Brazil 总被引:1,自引:0,他引:1
José Antônio Baptista Neto Franz Xaver Gingele Thomas Leipe Isa Brehme 《Environmental Geology》2006,49(7):1051-1063
Ninety-two surface sediment samples were collected in Guanabara Bay, one of the most prominent urban bays in SE Brazil, to
investigate the spatial distribution of anthropogenic pollutants. The concentrations of heavy metals, organic carbon and particle
size were examined in all samples. Large spatial variations of heavy metals and particle size were observed. The highest concentrations
of heavy metals were found in the muddy sediments from the north western region of the bay near the main outlets of the most
polluted rivers, municipal waste drainage systems and one of the major oil refineries. Another anomalous concentration of
metals was found adjacent to Rio de Janeiro Harbour. The heavy metal concentrations decrease to the northeast, due to intact
rivers and the mangrove systems in this area, and to the south where the sand fraction and open-marine processes dominate.
The geochemical normalization of metal data to Li or Al has also demonstrated that the anthropogenic input of heavy metals
have altered the natural sediment heavy metal distribution. 相似文献
123.
V. M. Hamza R. R. Cardoso C. F. Ponte Neto 《International Journal of Earth Sciences》2008,97(2):233-239
Pollack and Chapman, hereafter referred to as P&C, argue that: (1) errors arising from lack of quality control in the IHFC
database are not important and not properly documented, (2) resolution of spatial patterns in global heat flux distribution
should not be represented by spherical harmonics and (3) heat flow in young oceanic crust and global heat loss are better
represented by a contested 1-D cooling model than by the data. We disagree and provide additional information that may help
clear up such misunderstandings. We also mention briefly the results of a new improved thermal model of the lithosphere that
satisfactorily reproduces the main features identified in observational data sets of heat flow and ocean floor bathymetry.
Thus, there is no reason to invoke the ad hoc hypothesis of large-scale hydrothermal circulation in the ocean crust. 相似文献
124.
Arthur Ayres Neto Vanessa Alves da Costa Clara Pinto Ferreira Maia Porto Thais Cristina Vargas Garrido Jean-Pierre Hermand 《Marine Georesources & Geotechnology》2020,38(4):437-449
AbstractMarine mining is the ocean’s new exploration frontier, and polymetallic crusts (PMCs) and ferromanganese nodules are considered a strategic resource for the future. Acoustic geophysical methods are a valuable tool for oceanic research and have been employed for several decades in the exploration of marine resources and environmental evaluations. The main objective of this work was to investigate the correlation between the chemical composition of PMCs from three different areas along the Brazilian continental margin and their physico-acoustic attributes (P-wave velocity, density and acoustic impedance). The results show that the geoacoustic properties of PMCs are correlated to their chemical composition. Measurements showed positive and negative trends between acoustic impedance and studied elements (Fe, Mn, Co, Cu, Zn, W and Ni) according to the direction of measurement, indicting high anisotropy levels. Our study sheds initial light on the correlation between acoustic properties and metal content of PMCs. The study facilitates assessments of the acoustic responses of PMCs allowing more efficient prospection and exploitation compared to ship-board geophysical techniques that are too qualitative to identify PMCs. The results can contribute to determining the best procedures and techniques for more efficient future exploration of this resource. 相似文献