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41.
Suman Goyal M Mohapatra Ashish Kumar S K Dube Kushagra Rajendra P Goswami 《Journal of Earth System Science》2016,125(7):1353-1363
Indian region is severely affected by the tropical cyclones (TCs) due to the long coast line of about 7500 km. Hence, whenever any low level circulation (LLC) forms over the Indian Seas, the prediction of its intensification into a TC is very essential for the management of TC disaster. Satellite Application Centre (SAC) of Indian Space Research Organization (ISRO), Ahmedabad, has developed a technique to predict TCs based on scatterometer-derived winds from the polar orbiting satellite, QuikSCAT and Oceansat-II. The India Meteorological Department (IMD) has acquired the technique and verified it for the years 2010–2013 for operational use. The model is based on the concept of analogs of the sea surface wind distribution at the stage of LLC or vortex (T1.0) as per Dvorak’s classifications, which eventually leads to cyclogenesis (T2.5). The results indicate that the developed model could predict cyclogenesis with a probability of detection of 61% and critical success index of 0.29. However, it shows high over-prediction of the model is better over the Bay of Bengal than over Arabian Sea and during post-monsoon season (September–December) than in pre-monsoon season (March–June). 相似文献
42.
Rajendra Singh P. K. Mandal A. K. Singh R. Kumar A. Sinha 《Rock Mechanics and Rock Engineering》2008,41(3):421-444
Summary Considering ground instability problems of underground coal mines at shallow covers, this paper reviews and describes problems
of optimal extraction of coal stuck below surface/subsurface constraints at Indian coal fields. Importance of thickness and
quality of inter-burden between the working horizon and surface/subsurface constraints is discussed from a ground movement
point of view during optimisation of coal recovery by underground mining beneath the constraints. A CIMFR, formerly CMRI idea,
known as Wide Stall Method, was found suitable to overcome the limitations of non-effective-width based optimisation of recovery
of coal, trapped in pillars below surface/subsurface objects, at shallow cover. The involved rock mechanics concept and three
successful field trials of the Wide Stall Method under three different geo-mining conditions of the country are also briefly
given in this paper.
Author’s address: Rajendra Singh, Central Institute of Mining and Fuel Research (CIMFR, formerly CMRI), Barwa Road, Dhanbad,
826001 Jharkhand, India 相似文献
43.
Rajendra Sharma H. C. Gouda R. K. Singh B. V. Nagaraju 《Journal of the Geological Society of India》2012,79(1):11-29
The study of aeromagnetic data over parts of Assam-Meghalaya has delineated major discontinuities representing faults/ fractures/
contacts/ shears and magnetic body axes, which helped in understanding the regional and structural setup of the area. The
known Barapani and Dapsi Thrusts, Dudhnai Fault and three strong magnetic anomalies with reverse magnetisation have been delineated.
The quantitative analysis of aeromagnetic data brought out the depths of magnetic interfaces and the magnetic picture of different
layers, which also helped in understanding the regional and structural setup. The contact modeling across few profile sections
showed the depths to the top of contacts and the map of magnetic-basement-depth-model revealed the undulations of the basement.
Magnetic body axes of several magnetic anomalies and also several magnetic discontinuities representative of faults/ fractures/
contacts/ shears system in the area along with five potential blocks for mineral prospecting are the main outcome of this
exercise. The seismotectonic activity associated with the magnetic features has also been studied to understand the structural
setup. 相似文献
44.
Precambrian iron ores of the Singhbhum-North Orissa region occur in eastern India as part of the Iron Ore Group (IOG) within the broad horse-shoe shaped synclinorium. More than 50% of Indian iron ore reserves occur in this region. Massive-hard, flaky-friable, blue dust and lateritic varieties of iron ores are the major ore types, associated with banded hematite, jasper and shales. These ores could have formed as a result of supergene enrichment through gradual but extensive removal of silica, alumina and phosphorus from banded iron formations and ferruginous shale. Attempts for optimal utilization of these resources led to various ore characterization studies using chemical analysis, ore and mineral petrography, XRD analysis, SEM and electron probe micro analysis (EPMA). The ore chemistry indicates that the massive hard ores and blue dust have high iron, low alumina and phosphorus contents. Because of high quality, these ores do not require any specialized beneficiation technique for up-gradation. However, flaky-friable, lateritised and goethitic ores are low in iron, high in alumina and phosphorus contents, requiring specific beneficiation techniques for up-gradation in quality. XRD, SEM and ore microscopic studies of massive hard ores indicate the presence of hematite and goethite, while flaky and lateritic ores show a higher concentration of goethite, kaolinite, gibbsite and hematite. EPMA studies show the presence of adsorbed phosphorous as fine dust in the hard ores. Sink and float studies reveal that most of the gangue minerals are not completely liberated in the case of goethitic and lateritic ores, even at finer fractions. 相似文献
45.
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47.
Risk perception and evacuation decisions of Florida tourists under hurricane threats: a stated preference analysis 总被引:2,自引:2,他引:0
Corene Matyas Sivaramakrishnan Srinivasan Ignatius Cahyanto Brijesh Thapa Lori Pennington-Gray Jorge Villegas 《Natural Hazards》2011,59(2):871-890
Though most hurricane evacuation studies have focused on residents, tourists are also a vulnerable population. To assess their
perceptions of risk and evacuation likelihood under different hurricane conditions, we surveyed 448 tourists visiting central
Florida. Respondents viewed four maps emulating track forecast cones produced by the National Hurricane Center and text information
featuring variations of storm intensity, coast of landfall, centerline position relative to the survey site, time until landfall,
and event duration. We performed chi-square tests to determine which hurricane conditions, and aspects of tourists such as
their demographics and previous hurricane experience, most likely influenced their ratings of risk and evacuation likelihood
for respondents located on Pinellas County beaches or inland near Orlando, FL. Highly rated scenarios featured a Category
4 hurricane making landfall along the Gulf Coast with the centerline passing over the sampling site. Overall, tourists that
indicated the highest risk and evacuation ratings were not previously affected by a hurricane, had a trip duration of less
than 6 days, and had checked for the possibility of a hurricane strike before departure. However, results for other tourist
attributes differed between tourists in coastal and inland locations. We found that although somewhat knowledgeable about
hurricanes, tourists misinterpreted the track forecast cone and hurricane conditions, which led to a lower perception of risk
and subsequent likelihood to evacuate. Tourists, particularly those from outside of Florida, need to be better educated about
the risks they face from hurricanes that make landfall. 相似文献
48.
49.
Uplifted crust in parts of western India 总被引:1,自引:0,他引:1
H. C. Tewari G. Surya Prakasa Rao B. Rajendra Prasad 《Journal of the Geological Society of India》2009,73(4):479-488
During northward movement of the Indian sub-continent, after its breakup from the Gondwanaland in the Late Cretaceous, the
western part of India traversed over the Reunion plume. The Saurashtra peninsula and the Cambay Basin are two important geological
regions in this part. Two and half dimensional density models, based on the crustal seismic structure, were generated to establish
a relationship between these two regions. These models indicate that the crust is 32–33 km thick in the eastern Saurashtra
and the northern part of the Cambay Basin. The shallower crust is in a triangular region formed by the extension of the western
limb of the Proterozoic Aravalli trend in Saurashtra, its eastern limb and the Narmada fault in the south. Compared to 36–37
km thick crust to the west and 38–40 km to the east of this region the crust in the above triangular region is uplifted by
4 to 6 km. This uplift took place either after the deposition of Mesozoic sediments or was concomitant with the rise of Reunion
plume prior to the extrusion of the Deccan volcanics as the region was close to the axis of the plume. 相似文献
50.
Dwarka River Basin is one of the fluoride affected river basin in Birbhum, West Bengal. In the present research work, various controlling factors for fluoride contamination in groundwater i.e., geology, aquifer type, groundwater table, soil, rainfall, geomorphology, drainage density, land use land cover, lineament and fault density, slope and elevation were considered to delineate the potential fluoride contamination zones within Dwarka River Basin in Birbhum. Assigning weights and ranks to various inputs factor class and their sub-class respectively was carried out on the basis of knowledge driven method. Weighted overlay analysis was carried out to generate the final potential fluoride contamination zones which are classified into two broad classes i.e., ‘high’ and ‘low’, and it is observed that major portion of the study area falls under low fluoride contamination category encompassing 88.61% of the total area which accounts for 759.48 km2 and high fluoride contaminated region accounts for 11.40% of the total study area encompassing an area of about 97.67 km2. Majority of high fluoride areas fall along the flood plain of Dwarka River Basin. Finally, for validation 197 reported points within Dwarka having fluoride in underground water are overlaid and an overall accuracy of 92.15% is observed. An accuracy of 83.21% and 84.24% is obtained for success and prediction rate curve respectively. 相似文献