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581.
Landsat data to evaluate urban expansion and determine land use/land cover changes in Penang Island,Malaysia 总被引:3,自引:1,他引:2
Kok Chooi Tan Hwee San Lim Mohd Zubir MatJafri Khiruddin Abdullah 《Environmental Earth Sciences》2010,60(7):1509-1521
Land surface temperature (LST) plays an important role in local, regional and global climate studies. LST controls the distribution
of the budget for radiation heat between the atmosphere and the earth’s surface. Therefore, it is important to evaluate abrupt
changes in land use/land cover (LULC). Penang Island, Malaysia has been experiencing a rapid and drastic change in urban expansion
over the past two decades due to growth in industrial and residential areas. The aim of this study was to investigate and
evaluate the impact of LST with respect to land use changes in Penang Island, Malaysia. Three supervised classification techniques
known as maximum likelihood, minimum distance-to-mean and parallelepiped were applied to the images to extract thematic information
from the acquired scene by using PCI Geomatica 10.1 image processing software. These remote sensing classification techniques
help to examine land-use changes in Penang Island using multi-temporal Landsat data for the period of 1999–2007. Training
sites were selected within each scene and seven land cover classes were assigned to each classifier. The relative performance
of each technique was evaluated. The accuracy of each classification map was assessed using a reference data set consisting
of a large number of samples collected per category. Two Landsat satellite images captured in 1999 and 2007 were chosen to
classify the LULC types using the maximum likelihood classification method, determined from visible and near-infrared bands.
The study revealed that the maximum likelihood classifier produced superior results and achieved a high degree of accuracy.
The LST and normalised difference vegetation index (NDVI) were computed based on changes in LULC. The results showed that
the urban (highly built-up) area increased dramatically, and grassland area increased moderately. Inversely, barren land decreased
obviously, and forest area decreased moderately. While urban (minimally built-up) area decreased slightly. These changes in
LULC caused at significant difference in LST between urban and rural areas. Strong correlation values were observed between
LST and NDVI for all LULC classes. The remote sensing technique used in this study was found to be efficient; it reduced the
time for the analysis of the urban expansion, and it was found to be a useful tool to evaluate the impact of urbanisation
with LST. 相似文献
582.
Iron isotope compositions of carbonatites record melt generation, crystallization, and late-stage volatile-transport processes 总被引:2,自引:0,他引:2
Clark M. Johnson Keith Bell Brian L. Beard Aaron I. Shultis 《Mineralogy and Petrology》2010,98(1-4):91-110
Carbonatites define the largest range in Fe isotope compositions yet measured for igneous rocks, recording significant isotopic fractionations between carbonate, oxide, and silicate minerals during generation in the mantle and subsequent differentiation. In contrast to the relatively restricted range in δ56Fe values for mantle-derived basaltic magmas (δ56Fe?=?0.0?±?0.1‰), calcite from carbonatites have δ56Fe values between ?1.0 and +0.8‰, similar to the range defined by whole-rock samples of carbonatites. Based on expected carbonate-silicate fractionation factors at igneous or mantle temperatures, carbonatite magmas that have modestly negative δ56Fe values of ~ ?0.3‰ or lower can be explained by equilibrium with a silicate mantle. More negative δ56Fe values were probably produced by differentiation processes, including crystal fractionation and liquid immiscibility. Positive δ56Fe values for carbonatites are, however, unexpected, and such values seem to likely reflect interaction between low-Fe carbonates and Fe3+-rich fluids at igneous or near-igneous temperatures; the expected δ56Fe values for Fe2+-bearing fluids are too low to produced the observed positive δ56Fe values of some carbonatites, indicating that Fe isotopes may be a valuable tracer of redox conditions in carbonatite complexes. Further evidence for fluid-rock or fluid-magma interactions comes from the common occurrence of Fe isotope disequilibrium among carbonate, oxide, silicate, and sulfide minerals in the majority of the carbonatites studied. The common occurrence of Fe isotope disequilibrium among minerals in carbonatites may also indicate mixing of phenocyrsts from distinct magmas. Expulsion of Fe3+-rich brines into metasomatic aureols that surround carbonatite complexes are expected to produce high-δ56Fe fenites, but this has yet to be tested. 相似文献
583.
Sangheon Yi Chang-Gyun Han Keun-Chang Oh In Sun Seo Dongwook Kim Jaeyoung Lee Min Han Hanwoo Choi Jaesoo Lim Sujeong Park Chang-Pyo Jun Taesop Cho 《第四纪科学杂志》2022,37(1):100-113
We comprehensively analyzed sediments obtained from an archeological excavation. A trench sediment profile of Maedun Cave (MC), South Korea, was analyzed geoarchaeologically. Multi-proxy analyses (palynomorphs, grain size, magnetic susceptibility, animal bones and artifacts) reflected the vegetation, hydroclimate and lives of prehistoric people at Marine Isotope Stage (MIS) 3 (ca. 40–30k cal a bp ) in the early Late Paleolithic. The palynoflora consisted of pollen and non-pollen palynomorphs. Under the air-circulation system in the cave, anemophilous pollen flowed in during the day, whereas waterborne pollen and spores, and freshwater algae, were transported by flooding during the summer monsoon rainy season. Mixed conifer and deciduous broad-leaved forest with an understory of pteridophytes flourished around the north-east central Korean Peninsula during MIS 3. Freshwater algae and grass pollen records may reflect precipitation intensity. It is assumed that they had flowed in during flooding caused by high precipitation during the enhanced East Asian summer monsoon, corresponding to Dansgaard–Oeschger (D/O) events 5 and 8 of δ18O GISP2 and Hulu Cave. The prehistoric people hunted herbivorous animals in the area around MC and sheltered inside it seasonally. They also used the grains of oats growing near the dwelling as a source of food. 相似文献