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51.
MAGSAT data and Curie-depth below Deccan flood basalts (India) 总被引:3,自引:0,他引:3
Ground and airborne magnetic data are severely disturbed due to random susceptibility variations in Deccan flood basalts. However, Magnetic Satellite (MAGSAT) data over the Deccan flood basaltic region of the Indian subcontinent exhibit filtering of surficial noise. Three passes over Deccan traps show a low at about 20°N latitude and a high at about 23°N latitude. Spectral analysis of these passes and an available 2-D MAGSAT vertical intensity map indicate a deep (40±4 km) magnetic interface. It is interesting to note that the determination of Curie-depth from MAGSAT matches and confirms the geothermal data model. The estimates correspond to the Moho depth derived from gravity and deep seismic sounding studies. The study suggests a continental shield-like geothermal gradient of about 14°C/km below the area. 相似文献
52.
53.
Measurements of river water quality at Haridwar, India, taken during 2005–2006 show that the river water does not meet the World Health Organization and Bureau of Indian Standards criteria of drinking water quality, especially with respect to total coliform and fecal coliform. This study investigates the removal of pathogens at a river bank filtration site in Haridwar. Using the quality of river water and the quality of abstracted water from a nearby production well, semi‐empirical models based on the concept of filtration coefficient are developed and tested for their effectiveness in removing pathogens under varying bacteriological quality of source water. A two‐tier model, which includes the effect of clogged layer, is developed to obtain an equivalent filtration coefficient. This coefficient is found to be linearly related with natural logarithm of the concentration of pathogens in the source water. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
54.
Praveen K. Thakur Sreyasi Maiti Nanette C. Kingma V. Hari Prasad S. P. Aggarwal Ashutosh Bhardwaj 《Natural Hazards》2012,61(2):501-520
Vulnerability assessment of natural disasters is a crucial input for risk assessment and management. In the light of increasing
frequency of disasters, societies must become more disaster resilient. This research tries to contribute to this aim. For
risk assessment, insight is needed into the hazard, the elements at risk and their vulnerabilities. This study focused on
the estimation of structural vulnerability due to flood for a number of structural elements at risk in the rural area of Orissa,
India (Kendrapara), using a community-based approach together with geospatial analysis tools. Sixty-three households were
interviewed about the 2003 floods in 11 villages and 166 elements at risk (buildings) were identified. Two main structural
types were identified in the study area, and their vulnerability curves were made by plotting the relationships between flood
depth and vulnerability for each structural type. The vulnerability ranges from 0 (no damage) to 1 (collapse/total damage).
Structural type-1 is characterized by mud wall/floor material and a roof of paddy straw, and structural type-2 is characterized
by reinforced cement concrete (RCC) walls/floor and a RCC roof. The results indicate that structural type-1 is most vulnerable
for flooding. Besides flood depth, flood duration is also of major importance. Houses from structural type-1 were totally
collapsed after 3 days of inundation. Damage of the houses of structural type-2 began after 10 days of inundation. 相似文献
55.
56.
The petrological studies on Khadsaliya lignites from Bhavnagar district have been carried out for their microconstituent’s
characterization. Quantitative estimation of macerals reveal, due to high amount of macerals of huminite group, that this
lignite deposits has formed from forest dominated vegetation in a fast subsiding basin, experiencing almost uniform environmental
conditions, with slight intermittent fluctuations. The rank based on Ro max % values indicates that lignites are less mature and have not reached the sub-bituminous stage of coalification as those
of the lignites from Panandhro (Gujarat) and Neyveli (Tamil Nadu) fields. High pyrite content in the Khadsaliya lignite makes
it not much suitable for combustion purpose. 相似文献
57.
P. Thakur S. Ghose B. C. Paul 《Monthly notices of the Royal Astronomical Society》2009,397(4):1935-1939
We study modified Chaplygin gas (MCG) as a candidate for dark energy and predict the values of parameters of the gas for a physically viable cosmological model. The equation of state of MCG involves three parameters: B , A and α. The permitted values of these parameters are determined with the help of a dimensionless age parameter ( H 0 t 0 ) and H ( z ) − z data. Specifically, we study the allowed ranges of values of the B parameter in terms of α and As ( As is defined in terms of the parameters in the theory). We explore the constraints of the parameters in the cold dark matter and unified dark matter energy models, respectively. 相似文献
58.
59.
H. S. Negi N. K. Thakur Rajeev Kumar Manoj Kumar 《Journal of Earth System Science》2009,118(6):711-720
Seasonal snow cover is a vital natural resource in the Himalaya. Monitoring of the areal extent of seasonal snow cover is
important for both climatological studies as well as hydrological applications. In the present paper, snow cover monitoring
was carried out to evaluate the region-wise accumulation and ablation pattern of snow cover in Pir Panjal and Shamshawari
ranges of Kashmir valley. The study was carried out for the winter period between November and April of 2004–05, 2005–06 and
2006–07, using multi-temporal WiFS sensor data of IRS-1C/1D satellites. The study shows reduction in the areal extent of seasonal
snow cover and rising trend of maximum temperature in three winters for the entire Kashmir valley. This has been validated
with 20 years (1988–89 to 2007–08) climatic conditions prevailed in both ranges of Kashmir valley. Region-wise study shows
the spatial and temporal variability in seasonal snow cover within Kashmir valley. Advance melting was observed in Banihal
and Naugam/Tangdhar regions than Gurez and Machhal regions. Different geographical parameters of these regions were studied
to evaluate the influence on snow cover and it was observed that altitude and position of region with respect to mountain
range are the deciding factors for retaining the seasonal snow cover for longer duration. Such region-wise study of snow cover
monitoring, can provide vital inputs for planning the hydropower projects, development in habitat areas, recreational and
strategic planning in the region. 相似文献
60.
S.C. Patel S. Ravi Y. Anilkumar A. Naik S.S. Thakur J.K. Pati S.S. Nayak 《Journal of Asian Earth Sciences》2009,34(3):336-346
Mafic xenoliths of garnet pyroxenite and eclogite from the Wajrakarur, Narayanpet and Raichur kimberlite fields in the Archaean Eastern Dharwar Craton (EDC) of southern India have been studied. The composition of clinopyroxene shows transition from omphacite (3–6 wt% Na2O) in eclogites to Ca pyroxene (<3 wt% Na2O) in garnet pyroxenites. Some of the xenoliths have additional phases such as kyanite, enstatite, chromian spinel or rutile as discrete grains. Clinopyroxene in a rutile eclogite has an XMg value of 0.70, which is unusually low compared to the XMg range of 0.91–0.97 for all other samples. Garnet in the rutile eclogite is also highly iron-rich with an end member composition of Prp26.5Alm52.5Grs14.7Adr5.1TiAdr0.3Sps1.0Uv0.1. Garnets in several xenoliths are Cr-rich with up to 8 mol% knorringite component. Geothermobarometric calculations in Cr-rich xenoliths yield different P–T ranges for eclogites and garnet pyroxenites with average P–T conditions of 36 kbar and 1080 °C, and 27 kbar and 830 °C, respectively. The calculated P–T ranges approximate to a 45 mW m?2 model geotherm, which is on the higher side of the typical range of xenolith/xenocryst geotherms (35–45 mW m?2) for several Archaean cratons in the world. This indicates that the EDC was hotter than many other shield regions of the world in the mid-Proterozoic period when kimberlites intruded the craton. Textural and mineral chemical characteristics of the mafic xenoliths favour a magmatic cumulate process for their origin as opposed to subducted and metamorphosed oceanic crust. 相似文献