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1.
Reducing Emissions from Deforestation and Forest Degradation projects currently cover an area approximately twice the size of Germany and challenge traditional concepts of centralization and decentralization in studies of environmental governance. Emerging from the interactions of a complex network of actors, Reducing Emissions from Deforestation and Forest Degradation demonstrates that transnational governance networks of organizations can become spatially centralized. Using a historical analysis of the development of Reducing Emissions from Deforestation and Forest Degradation, we argue that the evolution of Reducing Emissions from Deforestation and Forest Degradation policy has been directed primarily from donor countries, especially in North America and Europe. Adopting a social network analysis approach, we present findings from a new dataset of collaboration on 276 Reducing Emissions from Deforestation and Degradation, avoided deforestation, and sustainable forest management projects that began some on-the-ground operations between 1989 and June 2012, finding that organizations in donor countries have from the beginning been the central actors in the Reducing Emissions from Deforestation and Forest Degradation network. We conclude that Reducing Emissions from Deforestation and Forest Degradation exhibits spatial centralization within transnational governance architectures despite institutional fragmentation, raising important normative questions about participation in transnational forest governance.  相似文献   
2.
A lava channel identified on the wall of an Elysium Planitia impact crater is investigated to identify the dominant erosion mechanism, mechanical vs. thermal, acting during channel formation. Observations of channel morphology are used to supplement analytical models of lava channel formation in order to calculate the duration of channel formation, the velocity of the lava flowing through the channel, and the erosion rate in each erosion regime considered. Results demonstrate that the channel observed in the Elysium Planitia impact crater formed primarily due to mechanical erosion. In a more general sense, results of this study suggest that lava channels can form primarily due to thermal erosion in the presence of more gradual slopes and more consolidated substrates whereas lava channels can form primarily due to mechanical erosion in the presence of more energetic flows on steeper slopes and more poorly consolidated substrates. Therefore, both erosion regimes must be considered when analyzing origins of eroded lava channels that cut through strata of different strengths.  相似文献   
3.
Caleb I. Fassett 《Icarus》2007,189(1):118-135
Ceraunius Tholus, a Hesperian-aged volcano in the Tharsis region, is characterized by small radial valleys on its flanks, and several larger valleys originating near its summit caldera. All of these large valleys drain from near the lowest present portion of the caldera rim and down the flanks of the volcano. The largest valley debauches into Rahe Crater (an oblique impact crater), forming a depositional fan. Recent study of climate change on Mars suggests that many low-latitude regions (especially large volcanic edifices) were periodically the sites of snow accumulation, likely triggered by variations in spin orbital parameters. We apply a conductive heat flow model to Ceraunius Tholus that suggests that following magmatic intrusion, sufficient heating would be available to cause basal melting of any accumulated summit snowpack and produce sufficient meltwater to cause the radial valleys. The geometry of the volcano summit caldera suggests that meltwater would also accumulate in a volumetrically significant caldera lake. Analysis of the morphology and volumes of the largest valley, as well as depositional features at its base, suggest that fluvial erosion due to drainage of this summit caldera lake formed the large valleys, in a manner analogous to how valleys were formed catastrophically from a lake in Aniakchak caldera in Alaska. Moreover, the event which carved the largest valley on Ceraunius Tholus appears to have led to the formation of a temporary lake within Rahe Crater, at its base. The more abundant, small valleys on the flanks are interpreted to form by radial drainage of melted ice or snow from the outside of the caldera rim. Comparison of Ceraunius Tholus with the volcano-capping Icelandic ice sheet Myrdalsjokull provides insight into the detailed mechanisms of summit heating, ice-cap accumulation and melting, and meltwater drainage. These observations further underline the importance of a combination of circumstances (i.e., climate change to produce summit snowpack and an active period of magmatism to produce melting) to form the valley systems on some martian volcanoes and not on others.  相似文献   
4.
A series of new radio-continuum (λ=20 cm) mosaic images focused on the NGC?300 galactic system were produced using archived observational data from the VLA and/or ATCA. These new images are both very sensitive (rms?=60 μJy) and feature high angular resolution (<10?″). The most prominent new feature is the galaxy’s extended radio-continuum emission, which does not match its optical appearance. Using these newly created images a number of previously unidentified discrete sources have been discovered. Furthermore, we demonstrate that a joint deconvolution approach to imaging this complete data-set is inferior when compared to an immerge approach.  相似文献   
5.
Samples taken from a shooting range near Blacksburg, VA, USA provide information about the reservoirs and pathways of lead at shooting ranges in an upland setting and humid environment. The metallic lead shot corrodes rapidly and develops a coating of hydrocerussite (Pb3(CO3)2(OH)2). Hydrocerussite dissolution releases soluble lead at concentrations ranging from 2 ppb to 2 ppm depending the soil pH values at this site. This soluble lead is captured by the Fe and Mn oxides and carbonates soil fractions. The highest concentration of extractable lead contained in the soil was directly correlated with the highest concentration of lead shot and bullets measured on the shotgun range surface. Eh-pH and hydrolysis diagrams provide a useful geochemical framework for understanding the corrosion process, recognizing the corrosion product(s), understanding their solubility, and identifying the geochemical barriers to lead migration that provides a basis for selecting best management practices for this and other shooting range.  相似文献   
6.
We considered small-scale measurement of permeability in pebbly sands having coarser grains supported in a finer grained matrix (fine packing). Our central question was whether air-based measurements are representative if made with a permeameter tip seal pressed in the sand matrix. We created pebbly sands and variably sorted sands, with systematic variation in aspects of their fine packing. We made permeability measurements by inserting the tip seal of an air permeameter in the matrix of these samples and compared them to the permeability of the composite sample determined by both water-based methods and theory. The air-permeameter measurements made in this way represent the permeability of the composite mixtures of coarser and finer grains and allow for the discernment of permeability between samples with different matrix compositions, ranging from fine to coarse sand. Furthermore, the collective results show that permeability differences in the pebbly sands and variably sorted sands with fine packing, however measured, are primarily due to differences in matrix permeability and not due to differences in the size or the percentage of the coarser grains.  相似文献   
7.
This paper examines the contribution of Export Processing Zones (EPZ) to employment creation in Kenya. The results suggest that employees in non-EPZ businesses are better paid than those in the EPZ. Firms in the EPZ employ more women than the Kenyan national average, although the proportion is less than the international average amongst EPZs. Against the general fear that EPZ enterprises offer little employment, the number of employees in the EPZ enterprises are comparable to those found outside as are working hours. A weak trade union movement, inefficient and inadequate social security, lack of employment benefits, lack of opportunities for training and promotion and low pay are problems encountered by those working in an EPZ.  相似文献   
8.
Soil moisture estimation from satellite earth observation has emerged effectively advantageous due to the high temporal resolution, spatial resolution, coverage, and processing convenience it affords. In this paper, we present a study carried out to estimate soil moisture level at every location within Enugu State Nigeria from satellite earth observation. Comparative analysis of multiple indices for soil moisture estimation was carried out with a view to evaluating the robustness, correlation, appropriateness and accuracy of the indices in estimating the spatial distribution of soil moisture level in Enugu State. Results were correlated and validated with In-Situ soil moisture observations from multi-sample points. To achieve this, the Topographic Wetness Index (TWI), based on digital elevation data, the Temperature Vegetation Dryness Index (TVDI) and an improved TVDI (iTVDI) incorporating air temperature and a Digital Elevation Model (DEM) were calculated from ASTER global DEM and Landsat images. Possible dependencies of the indices on land cover type, topography, and precipitation were explored. In-Situ soil moisture data were used to validate the derived indices. The results showed that there was a positive significant relationship between iTVDI versus TVDI (R = 0.53, P value < 0.05), while in iTVDI versus TWI (R = 0.00, P value > 0.05) and TVDI versus TWI (R = ?0.01, P value > 0.05) no significant relationship existed. There was a strong relationship between iTVDI and topography, land cover type, and precipitation than other indices (TVDI, TWI). In situ measured soil moisture values showed negative significant relationship with TVDI (R = ?0.52, P value < 0.05) and iTVDI (R = ?0.63, P value < 0.05) but not with TWI (R = ?0.10, P value > 0.05). The iTVDI outperformed the other two index; having a stronger relationship with topography, precipitation, land cover classes and soil moisture. It concludes that although iTVDI outperformed other indices (TVDI, TWI) in soil moisture estimation, the decision of which index to apply is dependent on available data, the intent of usage and spatial scale.  相似文献   
9.
The Tasmanian rock lobster industry has been managed by Individually Transferable Quotas (ITQs) and several input control measures since 1998. In this study, nine years of rock lobster fishing business data were used to categorise the catch and quota ownership traits and examine the response to the introduction of ITQ management. More specifically the study investigates how profit drivers moderated industry structure change.  相似文献   
10.
Abundant evidence exists for glaciation being an important geomorphic process in the mid-latitude regions of both hemispheres of Mars, as well as in specific environments at near-equatorial latitudes, such as along the western flanks of the major Tharsis volcanoes. Detailed analyses of glacial landforms (lobate-debris aprons, lineated valley fill, concentric crater fill, viscous flow features) have suggested that this glaciation was predominantly cold-based. This is consistent with the view that the Amazonian has been continuously cold and dry, similar to conditions today. We present new data based on a survey of images from the Context Camera (CTX) on the Mars Reconnaissance Orbiter that some of these glaciers experienced limited surface melting, leading to the formation of small glaciofluvial valleys. Some of these valleys show evidence for proglacial erosion (eroding the region immediately in front of or adjacent to a glacier), while others are supraglacial (eroding a glacier’s surface). These valleys formed during the Amazonian, consistent with the inferred timing of glacial features based on both crater counts and stratigraphic constraints. The small scale of the features interpreted to be of glaciofluvial origin hindered earlier recognition, although their scale is similar to glaciofluvial counterparts on Earth. These valleys appear qualitatively different from valley networks formed in the Noachian, which can be much longer and often formed integrated networks and large lakes. The valleys we describe here are also morphologically distinct from gullies, which are very recent fluvial landforms formed during the last several million years and on much steeper slopes (∼20-30° for gullies versus ?10° for the valleys we describe). These small valleys represent a distinct class of fluvial features on the surface of Mars (glaciofluvial); their presence shows that the hydrology of Amazonian Mars is more diverse than previously thought.  相似文献   
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