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401.
Climate change as a global problem has moved relatively swiftly into high profile political debates over the last 20?years or so, with a concomitant diffusion from the natural sciences into the social sciences. The study of the human dimensions of climate change has been growing in momentum through research which attempts to describe, evaluate, quantify and model perceptions of climate change, understand more about risk and assess the construction of policy. Cultural geographers?? concerns with the construction of knowledge, the workings of social relations in space and the politics and poetics of place-based identities provide a lens through which personal, collective and institutional responses to climate change can be evaluated using critical and interpretative methodologies. Adopting a cultural geography approach, this paper examines how climate change as a particular environmental discourse is constructed through memory, observation and conversation, as well as materialised in farming practices on the Lizard Peninsula, Cornwall, UK. 相似文献
402.
403.
Graham Bird Paul A. Brewer Mark G. Macklin Mariyana Nikolova Tsvetan Kotsev Mihail Mollov Catherine Swain 《Applied Geochemistry》2010
Lead isotope signatures (207Pb/206Pb, 208Pb/206Pb, 208Pb/204Pb, 206Pb/204Pb), determined by magnetic sector ICP-MS in river channel sediment, metal ores and mine waste, have been used as geochemical tracers to quantify the delivery and dispersal of sediment-associated metals in the lower Danube River catchment. Due to a diverse geology and range of ore-body ages, Pb isotope signatures in ore-bodies within the lower Danube River catchment show considerable variation, even within individual metallogenic zones. It is also possible to discriminate between the Pb isotopic signatures in mine waste and river sediment within river systems draining individual ore bodies. Lead isotopic data, along with multi-element data; were used to establish the provenance of river sediments and quantify sedimentary contributions to mining-affected tributaries and to the Danube River. Data indicate that mining-affected tributaries in Serbia and Bulgaria contribute up to 30% of the river channel sediment load of the lower Danube River. Quantifying relative sediment contributions from mining-affected tributaries enables spatial patterns in sediment-associated metal and As concentrations to be interpreted in terms of key contaminant sources. Combining geochemical survey data with that regarding the provenance of contaminated sediments can therefore be used to identify foci for remediation and environmental management strategies. 相似文献
404.
Didier Miallier Pierre Boivin Catherine Deniel Alain Gourgaud Philippe Lanos Marie Sforna Thierry Pilleyre 《Comptes Rendus Geoscience》2010,342(11):847-854
The Puy de Dôme volcano is a trachytic lava dome, about 11,000 y old. New pyroclastic layers originating from the volcano itself were discovered covering the summit and the flanks of the volcano. These pyroclastic layers do not fit with the previous interpretation, assuming a non-explosive dome-forming eruption. The tephra display pyroclastic surge features and exhibit fresh trachytic lapilli, basement lithics, allogeneous basaltic lava and clinker fragments requiring an open vent eruption. This ultimate eruption occurred after a period of rest, long enough for vegetation to develop on the volcano, as evidenced by carbonized plant fragments. Radiocarbon dating of some of these fragments gave an age of c.10,700 y also suggesting a significant rest duration. 相似文献
405.
When modelling the turbulent dispersion of a passive tracer using Reynolds-averaged Navier–Stokes (RANS) simulations, two
different approaches can be used. The first consists of solving a transport equation for a scalar, where the governing parameters
are the mean velocity field and the turbulent diffusion coefficient, given by the ratio of the turbulent viscosity and the
turbulent Schmidt number Sc
t
. The second approach uses a Lagrangian particle tracking algorithm, where the governing parameters are the mean velocity
and the fluctuating velocity field, which is determined from the turbulence kinetic energy and the Lagrangian time T
L
. A comparison between the two approaches and wind-tunnel data for the dispersion in the wake of a rectangular building immersed
in a neutral atmospheric boundary layer (ABL) is presented. Particular attention was paid to the influence of turbulence model
parameters on the flow and concentration field. In addition, an approach to estimate Sc
t
and T
L
based on the calculated flow field is proposed. The results show that applying modified turbulence model constants to enable
correct modelling of the ABL improves the prediction for the velocity and concentration fields when the modification is restricted
to the region for which it was derived. The difference between simulated and measured concentrations is smaller than 25% or
the uncertainty of the data on 76% of the points when solving the transport equation for a scalar with the proposed formulation
for Sc
t
, and on 69% of the points when using the Lagrangian particle tracking with the proposed formulation for T
L
. 相似文献
406.
This article presents one of the first systematic usability investigations for a Volunteered Geographic Information (VGI) editor. This research is motivated by the fact that although VGI is now widely consumed, contribution rates are lagging considerably. Compared to traditional GIS interfaces, with complex interfaces resulting in high cognitive loads and barriers to participation, VGI tools and interfaces need to be easy to use and learn to encourage and facilitate contributions. This article develops a case study of OpenStreetMap, one of the most successful VGI projects, and its default editor, Potlatch2. Ten participants with no prior experience of VGI contribution, were instructed to contribute data to OSM in a structured exercise, while being monitored using an eye tracker and audio/video screen capture software. Each participant was asked to Think Aloud, i.e. describe what they were thinking and doing as they completed the tasks. The results highlight significant usability issues impacting learnability, especially from the perspective of a new contributor: hidden functionality, lack of user feedback between interactions and the inefficient and inconsistent placement of functionality and map controls. The facilitation of VGI contributions clearly depends on designing targeted interfaces, optimized to the needs of specific levels of contributors with defined goals and expectations. 相似文献
407.
Alexander?ProyerEmail author Edgar?Dachs Catherine?McCammon 《Contributions to Mineralogy and Petrology》2004,147(3):305-318
The relatively low-variance mineral assemblage of a talc-kyanite eclogite from Dabie Shan enabled application of both conventional geothermobarometers (garnet-clinopyroxene geothermometer and the garnet-omphacite-phengite geobarometer) and a multi-equilibrium method to determine peak P-T conditions (THERMOCALC, average PT). The results were highly discrepant: 840 °C / 31.1 kbar vs. 590 °C / 29.8 kbar. Mössbauer spectroscopy showed that Fe3+/Fetotal in omphacite was significantly higher than the value obtained from standard formula recalculation. When the activities were corrected for Fe endmembers, geothermobarometry gave consistent results (606 °C / 31.3 kbar vs. 585 °C / 30.8 kbar). These are close to those obtained earlier by average PT, confirming the robustness of the multi-equilibrium approach. The high Fe3+ concentration in omphacite is best explained using a Ca-eskola endmember Ca0.5[]0.5AlSi2O6
and allowing corresponding vacancies in the omphacite structure.Editorial responsibility: W. Schreyer 相似文献
408.
Jean-Philippe Bellot Laurent Bailly Catherine Lerouge Vincent Bouchot 《Mineralium Deposita》2004,39(5-6):576-582
The natural deformation of stibnite in relation to the kinematic history of a regional fault is resolved using microstructural analysis of massive stibnite along the Biards Fault in the Massif Central (France). Stibnite underwent intra-crystalline deformation associated with a strong linear and planar anisotropy. Lepidoblastic textures, undulatory extinction of oriented grains, growth of antimony between these grains, and a colour change of stibnite from white to black, result from dynamic recrystallisation. A range of asymmetric microstructures indicate non-coaxial deformation and a left-lateral sense of shear, related to the movement of the fault zone. The computed displacement corresponds to the geological offsets measured along the fault. We conclude that stibnite has microstructurally recorded the bulk kinematics of its host fault zone.Editorial Handling: F. Tornos 相似文献
409.
Alain Cocherie Catherine Guerrot C.Mark Fanning Albert Genter 《Comptes Rendus Geoscience》2004,336(9):775-787
Deep boreholes drilled in the basement of the Rhine Graben at Soultz-sous-Forêts have shown the presence of an ubiquitous monzogranite. Borehole GPK-2, with a total depth of 5090 m, also intersected a more leucocratic fine-grained two-mica granite, locally present below 4860 m depth and continuously found between 5047 and 5090 m. Thanks to trace elements and in particular to REE (rare-earth elements), it could be shown that the leucocratic rock is a differentiated expression of the potassic magma that was at the origin of the monzogranite pluton. This model agrees with Sr–Nd isotope data, even though a slight contribution from the pre-existing basement should be considered as well. Use of the U–Pb method on monzogranite from EPS-1 – after zircon dissolution – has yielded an emplacement age of 334.0+3.8/?3.5 Ma . Point dates obtained by SHRIMP II on the rare zircons from the fine-grained granite showed that it was emplaced in a basement with very heterogeneous ages, ranging from Early Proterozoic to Silurian. The estimated crystallization age of the last granite is 327±7 Ma , slightly later than, or sub-contemporaneous with, the emplacement of the common monzogranite, in agreement with structural constrains. To cite this article: A. Cocherie et al., C. R. Geoscience 336 (2004). 相似文献
410.