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51.
In Germany, landfilling and incineration are the main techniques for the disposal of waste. However, due to humid climatic
conditions, leakage of contaminated water from landfills into the subsurface poses a considerable threat to the environment.
Therefore, the German states require high safety standards for the construction of a landfill. Emphasis is put on the presence
of natural geological barrier rocks. Clay and silts, claystones and siltstones are best suited to meet the requirements defined
in legal waste regulations. With regard to retardation capacity, thickness is considered of higher importance than hydraulic
permeability. Suitable areas have to be reduced by legally excluded areas. A site search program in Lower Saxony revealed
that only 1% of the total state area falls into the best suitability category. Geoscientific investigations on the remaining
suitable areas have to become more detailed in the search progress. Geographical information systems (GIS) are the most adequate
tools to work on all involved data and to present and outline the results. GIS make the results transparent and understandable
to the public. These investigations are a necessary part of the environmental impact assessment which is obligatory for a
landfill site's construction. Criteria catalogues take all important aspects of the search process into consideration and
help to find the most suitable site.
Received: 17 March 1997 · Accepted: 6 June 1997 相似文献
52.
53.
Laboratory and theoretical studies have been made of the effects of ultraviolet photolysis of interstellar grain mantles which consist of combinations of hydrogen, oxygen, carbon and nitrogen — dirty ice. It is shown that processes involving photolysis (photoprocessing) of interstellar grains are important during most of their lifetime even including the time they spend in dense clouds. A laboratory designed to simulate the interstellar conditions is described. This is the first time such a laboratory has been able to provide results which may be directly scaled to the astrophysical situations involving interstellar grains and their environment. The evolution of grain analogs is followed by observing the infrared absorption spectra of photolyzed samples of ices deposited at 10 K. The creation and storage of radicals and the production of molecules occur as a result of reactions within the solid. A large number of molecules and radicals observed in the interstellar gas appear in the irradiated ices. Energy released during warm-up is seen from visible luminescence and inferred from vapor pressure enhancement which occurs during warming of photolyzed samples relative to unphotolyzed samples. The evolution of a grain and its role as a source as well as a sink of molecules is pictured as a statistical process within dense clouds. The gradual accretion on and photolysis of an individual grain provides the stored chemical energy the release of which is sporadically triggered by relatively mild events (such as low velocity grain-grain collisions) to produce the impulsive heating needed to eject or evaporate a portion of the grain mantle. An extremely complex and rather refractory substance possessing the infrared signatures of amino groups and carboxylic acid groups and having a maximum mass of 514 amu has been produced at a rate corresponding to a mass conversion rate of interstellar grains of between 2% and 20% in 107 yr. The shape and position of the astronomically observed 3.1 m band is duplicated in the laboratory and is shown to be a natural consequence of the processing of grain mantles.Invited contribution to the Proceedings of a Workshop onThermodynamics and Kinetics of Dust Formation in the Space Medium held at the Lunar and Planetary Institute, Houston, 6–8 September, 1978. 相似文献
54.
Echo-peak data of outer and normal incidence beams from five different Southern Ocean bottom topographic regions have been analysed. The Rice and Extremal probability density function (PDF) statistical approaches reveal that the seabed roughness is, in general, Gaussian in nature except in the case of the Kainan Maru seamount summit (area D). The outer beams of the Enderby abyssal plain (area C) echo-peak PDF statistics reveal the highest possible large-scale feature dominance. Interestingly, Extremal PDF fit parameters (!) from the Agulhas Basin (area A) show a less dominant large-scale roughness than in the case of area C. Large-scale feature dominance up to 15° beam angle is observed in the case of mixed roughness seabeds such as area B (southwest Indian ridge) and area E (Meteor Rise). No increase in the 30°-beam Extremal PDF parameters is observed in these areas. Maximum microtopographic roughness is documented in area D on the summit of Kainan Maru seamount. The estimated fit parameters using Extremal statistics of outer-beam peak data provide a better understanding of the scattering process. Previously determined power law and volume roughness parameters using composite roughness theory are given for the five different areas. These support the results obtained using Rice and Extremal PDFs. The existence of higher volume roughness parameters and power law parameters for medium-scale roughness, along with dominant microtopographic features, are evident from the results of this study. 相似文献
55.
The Political Life of Urban Streetscapes: Naming,Politics, and Place. Edited by Reuben Rose‐Redwood,Derek Alderman,and Maoz Azaryahu. xxii and 334 pp.: maps,ills. bibliog. index. Abingdon,U.K.: Routledge, 2018. $140.00 (hardcover), isbn 9781472475091.
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Joshua Hagen 《Geographical review》2018,108(4):634-636
56.
Andrew Hodson Angela Gurnell Martyn Tranter Jim Bogen Jon Ove Hagen Michael Clark 《水文研究》1998,12(1):73-86
Observations of suspended sediment concentration and discharge at two sites on the proglacial river network draining from a predominantly cold-based, High-Arctic glacier (Austre Brøggerbreen) are described. Analysis of these observations illustrates: (i) the relatively low suspended sediment yield from this basin in comparison with many other glacier basins reported in the open literature; (ii) sustained and possibly increasing availability of suspended sediment to the fluvial system as the ablation season progresses; and (iii) the role of the proglacial sandur as both a sediment source and sink. Field observations coupled with the results of the data analysis are used to make inferences concerning the changing nature and relative importance of sediment sources within the basin. © 1998 John Wiley & Sons, Ltd. 相似文献
57.
A. J. Hodson A. M. Gurnell R. Washington M. Tranter M. J. Clark J. O. Hagen 《水文研究》1998,12(3):509-526
This paper examines characteristics of meteorological and runoff time-series collected from the Brøggerbreen glacier basin, Svalbard, during 1991 and 1992. Proglacial discharge and electrical conductivity were monitored at two gauging stations: one immediately downstream of the terminus of Austre Brøggerbreen and another c. 2·5 km downstream, in order to assess the contribution of the intervening proglacial sandur. Meteorological time-series (incident radiation, wind speed and direction, air temperature and precipitation) were monitored on the proglacial sandur. Changes in wind direction, incident radiation receipt and air temperature were used as a basis for separating the time-series into different periods. These periods allowed the relative significance of advective and incident (short-wave) radiative forcing of air temperatures to be determined at diurnal and synoptic time-scales. The analysis shows that incident radiation dominated over advection in the forcing of diurnal variations in air temperature during all the periods. At the synoptic scale, both processes were periodically dominant in forcing air temperature variability. An examination of synoptic charts supports the use of ground level measurements to describe the effect of energy advection upon the synoptic air temperature variability and indicates the role of large-scale circulation patterns in the delivery of energy for ablation under different conditions. Interrelationships between the hydrological and meteorological time-series are then used to characterize the response of the glacierized part of the catchment to meteorological forcing throughout the two ablation seasons. The analyses show that the recession of the snowpack across the proglacial and glacial portions of the basin has an important effect on the catchment contributing area contributing to runoff and the lag between energy inputs and meltwater discharge outputs. © 1998 John Wiley & Sons, Ltd. 相似文献
58.
Rick A. Hagen Karsten Gohl Rainer Gersonde Gehard Kuhn David Völker V. N. Kodagali 《Geo-Marine Letters》1998,18(1):19-25
The De Gerlache Seamounts actually consist of two medium-sized guyots, with summits at depths of 350–600 m. Acoustic profiler
data show no significant sediment on these guyots. Alkaline basalts dredged from the summit of the eastern guyot yield K/Ar
ages between 20.1±1.0 and 23.2±1.2 Ma. Basement ridges and sediment-filled troughs between the guyots are associated with
the prominent gravity anomaly extending north from the Antarctic margin. This structure possibly played a role in the guyot
formation, however, the question of how the De Gerlache Seamounts are related to this gravity anomaly remains uncertain.
Received: 13 February 1997 / Revision received: 30 September 1997 相似文献
59.
60.
Glaciers in Svalbard: mass balance, runoff and freshwater flux 总被引:4,自引:1,他引:4
Gain or loss of the freshwater stored in Svalbard glaciers has both global implications for sea level and, on a more local scale, impacts upon the hydrology of rivers and the freshwater flux to fjords. This paper gives an overview of the potential runoff from the Svalbard glaciers. The freshwater flux from basins of different scales is quantified. In small basins (A < 10 km2 ), the extra runoff due to the negative mass balance of the glaciers is related to the proportion of glacier cover and can at present yield more than 20% higher runoff than if the glaciers were in equilibrium with the present climate. This does not apply generally to the ice masses of Svalbard, which are mostly much closer to being in balance. The total surface runoff from Svalbard glaciers due to melting of snow and ice is roughly 25 ± 5 km3 a−1 , which corresponds to a specific runoff of 680 ± 140 mm a−1 , only slightly more than the annual snow accumulation. Calving of icebergs from Svalbard glaciers currently contributes significantly to the freshwater flux and is estimated to be 4 ± 1 km3 a−1 or about 110 mm a−1 . 相似文献