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21.
The Arc Marine data model is a generalized template to guide the implementation of geographic information systems (GIS) projects in the marine environment. It developed out of a collaborative process involving research and industry shareholders in coastal and marine research. This template models and attempts to standardize common ocean and coastal data types to facilitate data sharing and analytical tool development. In this study, Arc Marine is extended from its core model to fit the research goals of the whale satellite-telemetry-tagging program of the Oregon State University Marine Mammal Institute (MMI). The study sought the best customization of the generic Arc Marine data model to enhance the key advantages of satellite telemetry for mapping the distribution and movement of endangered marine mammal species. It was found that three new groups of object classes were needed (Animal, Telemetry, and Operations). Further customization involved the development of a comprehensive framework for animal tracking with Argos satellite telemetry data. A new multidimensional data cube model was also devised, showing how this extension of Arc Marine serves as an appropriate target schema for the application of on-line analytical processing (OLAP) tools and spatial data mining of satellite telemetry tracking datasets.  相似文献   
22.
In 1964, E.H. Hammond proposed criteria for classifying and mapping physiographic regions of the United States. Hammond produced a map entitled “Classes of Land Surface Form in the Forty‐Eight States, USA”, which is regarded as a pioneering and rigorous treatment of regional physiography. Several researchers automated Hammond?s model in GIS. However, these were local or regional in application, and resulted in inadequate characterization of tablelands. We used a global 250 m DEM to produce a new characterization of global Hammond landform regions. The improved algorithm we developed for the regional landform modeling: (1) incorporated a profile parameter for the delineation of tablelands; (2) accommodated negative elevation data values; (3) allowed neighborhood analysis window (NAW) size to vary between parameters; (4) more accurately bounded plains regions; and (5) mapped landform regions as opposed to discrete landform features. The new global Hammond landform regions product builds on an existing global Hammond landform features product developed by the U.S. Geological Survey, which, while globally comprehensive, did not include tablelands, used a fixed NAW size, and essentially classified pixels rather than regions. Our algorithm also permits the disaggregation of “mixed” Hammond types (e.g. plains with high mountains) into their component parts.  相似文献   
23.
A Benthic Terrain Classification Scheme for American Samoa   总被引:2,自引:0,他引:2  
Coral reef ecosystems, the most varied on earth, continually face destruction from anthropogenic and natural threats. The U.S. Coral Reef Task Force seeks to characterize and map priority coral reef ecosystems in the U.S./Trust Territories by 2009. Building upon NOAA Biogeography shallow-water classifications based on Ikonos imagery, presented here are new methods, based on acoustic data, for classifying benthic terrain below 30 m, around Tutuila, American Samoa. The result is a new classification scheme for American Samoa that extends and improves the NOAA Biogeography scheme, which, although developed for Pacific island nations and territories, is only applicable to a maximum depth of 30 m, due to the limitations of satellite imagery. The scheme may be suitable for developing habitat maps pinpointing high biodiversity around coral reefs throughout the western Pacific.  相似文献   
24.
 Shallow marine carbonate sediments near the Dry Tortugas undergo extensive biogeochemical diagenesis upon deposition, resulting in postdepositional fabric comprised of micritic aggregates of clay-sized particles, a matrix of peloidal mud, and intraparticular cementation. Freshly deposited primary skeletons, mostly Halimeda fragments, yield micritic aggregates of clay-sized particles, which then form peloidal mud fabric upon compaction. The cryptocrystalline particles produced by micritization are later replaced by high magnesian calcite. Cementation is observed in the intra-particular microenvironment. However, no inter-particular, grain-binding cement was detected throughout the gravity core samples investigated.  相似文献   
25.
Elevated concentrations of Mo are present in both the waters and sediments of Tenmile Creek, downstream from the large Mo deposit at Climax. Colorado. Concentrations of Mo reach a maximum of 10mg/1 in the water and 384μ/g in the (?) 80 mesh fraction of the sediment. The Mo anomaly extends for more than 80 km downstream from Climax, and results from the mining and milling at Climax. Background Mo concentrations in the nearby mountainous area are < 10μg/l (water) and < 5μg/g (sediment). Immediately below three small unmined Mo-rich orebodies elsewhere in Colorado < 3μg/l Mo are present in the waters and 20–30μg/g Mo in the fine fraction of the sediments.The Mo in the sediment of Tenmile Creek is chiefly adsorbed on coatings of amorphous Fe oxyhydroxide. and is similar to its form below two small, unmined Mo deposits. Mining has not changed the character of the chemical processes responsible for Mo dispersion from the Climax site.A modified version of the WATEQF computer program (Plummeret al., 1976) predicts that Tenmile Creek is undersaturated with respect to ferrimolybdite. molybdenite, powellite, and ilsemannite. The Mo in the stream water occurs as the molybdate ion which can be adsorbed on amorphous Fe oxyhydroxides. These predictions are supported by the absence of Mo minerals in the sediment of Tenmile Creek.  相似文献   
26.
An investigation to characterize the extent and speciation of lead contamination in water, soil, and surrounding biota was conducted at a small-arms firing and skeet range in West Point, New York. Specifically, lead concentrations were examined in sediment, soil, water, plants, fish and invertebrates. There is an elevated concentration of lead in the soil and sediment up to 11,000 g/g and 340 g/g and also evidence of bioconcentration of the lead by the surrounding biota. Earthworms had up to 90% higher concentrations of lead while tadpoles showed 20% higher concentrations compared with their controls. Lead uptake by indigenous plants gave varying results. Two species bioconcentrated lead 20 and 55 times greater than the control plants. These differences were significant (P <0.05 level) when tested by the students t test. Further studies show that the total leachable lead was highest in the invertebrates and vertebrates but not in the plants.  相似文献   
27.
We measured organochlorine residues in three species of sea turtles from the Baja California peninsula, Mexico. Seventeen of 21 organochlorine pesticides analyzed were detected, with heptachlor epoxide and gamma-hexachlorocyclohexane the most prevalent (14 (40%) and 11 (31%) of the 35 tissue samples, respectively). PCBs were detected in all but one of the 9 turtles studied, with congener 18 the most commonly detected (8 (23%) of the samples). The dioxin-like congeners 118 and 180 were detected in 4 (11%) and 3 (9%) of the samples, respectively. Percent contribution of congeners was negatively correlated to their octanol-water partition coefficients, with kidney and muscle containing more lower-chlorinated congeners than liver or adipose samples. Levels of organochlorines detected in the present study were low, potentially attributable to the feeding habits of the predominant species collected in this study (herbivorous) and/or the samples obtained in an unindustrialized region.  相似文献   
28.
29.
Slavic and German colonization of the southern Baltic between the 8th and 15th centuries A.D. is well‐documented archaeologically and historically. Despite the large number of pollen profiles from Poland, few palaeoecological studies have examined the ecological impact of a process that was central to the expansion of European, Christian, societies. This study aims to redress this balance through multiproxy analysis of lake sediments from Radzyń Chełminski, Northern Poland, using pollen, element geochemistry (Inductively Coupled‐Optical Emission Spectroscopy [ICP‐OES]), organic content, and magnetic susceptibility. The close association between lake and medieval settlements presents the ideal opportunity to reconstruct past vegetation and land‐use dynamics within a well‐documented archaeological, historical, and cultural context. Three broad phases of increasing landscape impact are visible in the pollen and geochemical data dating from the 8th/9th, 10th/11th, and 13th centuries, reflecting successive phases of Slavic and German colonization. This involved the progressive clearance of oak‐hornbeam dominated woodland and the development of an increasingly open agricultural landscape. Although the castles and towns of the Teutonic Order remain the most visible signs of medieval colonization, the palynological and geochemical data demonstrate that the major phase of woodland impact occurred during the preceding phase of Slavic expansion; Germans colonists were entering a landscape already significantly altered.  相似文献   
30.
Braced frames are one of the most economical and efficient seismic resisting systems yet few full‐scale tests exist. A recent research project, funded by the National Science Foundation (NSF), seeks to fill this gap by developing high‐resolution data of improved seismic resisting braced frame systems. As part of this study, three full‐scale, two‐story concentrically braced frames in the multi‐story X‐braced configuration were tested. The experiments examined all levels of system performance, up to and including fracture of multiple braces in the frame. Although the past research suggests very limited ductility of SCBFs with HSS rectangular tubes for braces recent one‐story tests with improved gusset plate designs suggest otherwise. The frame designs used AISC SCBF standards and two of these frames designs also employed new concepts developed for gusset plate connection design. Two specimens employed HSS rectangular tubes for bracing, and the third specimen had wide flange braces. Two specimens had rectangular gusset plates and the third had tapered gusset plates. The HSS tubes achieved multiple cycles at maximum story drift ratios greater than 2% before brace fracture with the improved connection design methods. Frames with wide flange braces achieved multiple cycles at maximum story drift greater than 2.5% before brace fracture. Inelastic deformation was distributed between the two stories with the multi‐story X‐brace configuration and top story loading. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
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