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101.
Bas D. Katsoulis 《Climatic change》1987,10(1):67-79
Air temperature data of Athens are analysed to point out the variations caused by natural controls and anthropogenic activities. The study of the temperature records from 1858 to 1982 at Athens, on the southeast coast of Greece, supports the findings of earlier studies which indicate that the period of the 1920's to the 1950's were, climatologically, warmer than the preceding 60 yr and after about 1960. In particular, minimum temperatures show an increase from the 1920's to the 1980's, possibly due to the urbanization of the area. The climatological trends are clearly indicated in the data, when averaged over 30 yr and/or a numerical low-pass filtering technique is used. However, the sizes of the trends in climate are smaller than the interannual variations in the temperature measures. Over periods of several generations these small variations in climate cannot have had any effect on human activity when compared with the large effects caused by the interannual variability in the temperature. 相似文献
102.
J. Antoon van Hooft Stéphane Popinet Chiel C. van Heerwaarden Steven J. A. van der Linden Stephan R. de Roode Bas J. H. van de Wiel 《Boundary-Layer Meteorology》2018,167(3):421-443
We present a proof-of-concept for the adaptive mesh refinement method applied to atmospheric boundary-layer simulations. Such a method may form an attractive alternative to static grids for studies on atmospheric flows that have a high degree of scale separation in space and/or time. Examples include the diurnal cycle and a convective boundary layer capped by a strong inversion. For such cases, large-eddy simulations using regular grids often have to rely on a subgrid-scale closure for the most challenging regions in the spatial and/or temporal domain. Here we analyze a flow configuration that describes the growth and subsequent decay of a convective boundary layer using direct numerical simulation (DNS). We validate the obtained results and benchmark the performance of the adaptive solver against two runs using fixed regular grids. It appears that the adaptive-mesh algorithm is able to coarsen and refine the grid dynamically whilst maintaining an accurate solution. In particular, during the initial growth of the convective boundary layer a high resolution is required compared to the subsequent stage of decaying turbulence. More specifically, the number of grid cells varies by two orders of magnitude over the course of the simulation. For this specific DNS case, the adaptive solver was not yet more efficient than the more traditional solver that is dedicated to these types of flows. However, the overall analysis shows that the method has a clear potential for numerical investigations of the most challenging atmospheric cases. 相似文献
103.
Claudia Bas Juan P. Lancia Tomás Luppi Agustina Méndez‐Casariego Marcelo Kittlein Eduardo Spivak 《Marine Ecology》2014,35(3):319-331
The relationship between diet and feeding activity of intertidal crabs, and environmental cycles (tidal, daily and seasonal), habitat and level of the intertidal zone (high/low) was studied using Neohelice granulata (Brachyura, Varunidae) as a model. This is a semi‐terrestrial burrowing crab occupying different habitats in the Southwestern Atlantic coasts and estuaries from bare low intertidal mudflats to high intertidal salt marshes, and from fine, organic matter rich sediment to very coarse sediment with low content of organic matter. The study was carried out in two contrasting habitats of three sites with diverse sets of physical and biological conditions. Diet and feeding of adult N. granulata were indirectly studied through the proportion of food items and the presence/absence of food in crab stomachs, respectively. This species has a dual mode of feeding: predominantly herbivorous (live plants or plant litter in salt marshes) or deposit feeder (superficial sediment and detritus in mudflats), but the quantity and quality of ingested food varies among habitats and sites. A trend to omnivory (including algae and conspecifics) was detected in relation to low quality of resources. Feeding activity modulated by a complex interaction of factors varied according to spatial and/or temporal changes in some natural cycles. Males and non‐ovigerous females fed preferably after dark and during submersion periods, but also after emersion periods if mudflat sediment remained wet; salt marsh crab feeding is somewhat independent of light and tidal cycles. Ovigerous females almost never fed. Both diet and feeding activity of this crab seem to be flexible traits adapted to different combinations of physical and biological factors. 相似文献
104.
105.
Detlef P. van Vuuren Sebastiaan Deetman Jasper van Vliet Maarten van den Berg Bas J. van Ruijven Barbara Koelbl 《Climatic change》2013,118(1):15-27
Limiting climate change to 2 °C with a high probability requires reducing cumulative emissions to about 1600 GtCO2 over the 2000–2100 period. This requires unprecedented rates of decarbonization even in the short-run. The availability of the option of net negative emissions, such as bio-energy with carbon capture and storage (BECCS) or reforestation/afforestation, allows to delay some of these emission reductions. In the paper, we assess the demand and potential for negative emissions in particular from BECCS. Both stylized calculations and model runs show that without the possibility of negative emissions, pathways meeting the 2 °C target with high probability need almost immediate emission reductions or simply become infeasible. The potential for negative emissions is uncertain. We show that negative emissions from BECCS are probably limited to around 0 to 10 GtCO2/year in 2050 and 0 to 20 GtCO2/year in 2100. Estimates on the potential of afforestation options are in the order of 0–4 GtCO2/year. Given the importance and the uncertainty concerning BECCS, we stress the importance of near-term assessments of its availability as today’s decisions has important consequences for climate change mitigation in the long run. 相似文献
106.
Non Okumura Sebastiaan N. Jonkman Miguel Esteban Bas Hofland Tomoya Shibayama 《Natural Hazards》2017,88(3):1451-1472
This paper presents a methodology for tsunami risk assessment, which was applied to a case study in Kamakura, Japan. This methodology was developed in order to evaluate the effectiveness of a risk-reducing system against such hazards, also aiming to demonstrate that a risk assessment is possible for these episodic events. The tsunami risk assessment follows these general steps: (1) determination of the probability of flooding, (2) calculation of flood scenarios, (3) assessment of the consequences and (4) integration into a risk number or graph. The probability of flooding was approximated based on the data provided by local institutes, and the flood scenarios were modeled in 1D using the Simulating WAves till SHore model. Results showed that a tsunami in Kamakura can result in thousands of casualties. Interventions such as improvements in evacuation systems, which would directly reduce the number of casualties, would have a large influence in risk reduction. Although this method has its limits and constraints, it illustrates the value it can add to existing tsunami risk management in Japan. 相似文献
107.
M. J. Le Bas Yang Xueming Rex N. Taylor B. Spiro J. A. Milton Zhang Peishan 《Mineralogy and Petrology》2007,90(3-4):223-248
Summary New data on Sr and Nd isotope composition and major and trace element distribution in dolomite-calcite carbonatite dykes at
Bayan Obo are provided, and a Mid-Proterozoic age is deduced. The dykes and the neighbouring massive dolomite (H8) body have
similar geochemical characteristics, interpreted to indicate a carbonatitic magmatic origin. The occurrence of riebeckite-bearing
fenitized quartzites marginal to both dykes and H8 dolomite body, and the presence of xenoliths in the latter, supports this
conclusion. Taken together with previously published stable isotope data, these data confirm a mantle-derived origin for the
H8 body.
The oxygen isotope composition of the dolomite and magnetite in the dykes is lower than that in the fine-grained dolomite.
Oxygen data from samples of the coarse-grained dolomite host are either similar to the dykes or to the fine-grained type in
agreement with their other geochemical characteristics. The carbonate-magnetite thermometric pairs of the fine-grained dolomite
indicate a range of 350–540 °C, which is probably lower than that of the original main magmatic emplacement. This supports
the distinction made between the original coarse-grained dolomite marble and dyke composition from the later fine-grained
dolomite.
Thus the large H8 dolomite is interpreted as a carbonatite intrusion that contains wall-rock xenoliths and caused fenitization
of the hanging wall, foot wall and the xenoliths, and that the coarse-grained portions of the H8 marble are those portions
that, in the Late Proterozoic to Palaeozoic, escaped recrystallization to fine-grained dolomite and subsequent REE-Fe mineralization.
Currently at National Oceanography Centre, University of Southampton, Southampton, UK
An erratum to this article is available at . 相似文献