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11.
We propose to adopt a deep learning based framework using generative adversarial networks for ground-roll attenuation in land seismic data. Accounting for the non-stationary properties of seismic data and the associated ground-roll noise, we create training labels using local time–frequency transform and regularized non-stationary regression. The basic idea is to train the network using a few shot gathers such that the network can learn the weights associated with noise attenuation for the training shot gathers. We then apply the learned weights to test ground-roll attenuation on shot gathers, that are not a part of training input to obtain the desired signal. This approach gives results similar to local time–frequency transform and regularized non-stationary regression but at a significantly reduced computational cost. The proposed approach automates the ground-roll attenuation process without requiring any manual input in picking the parameters for each shot gather other than in the training data. Tests on field-data examples verify the effectiveness of the proposed approach. 相似文献
12.
13.
Lekshmi S Chattopadhyay Rajib Kaur Manpreet Joseph Susmitha Phani R. Dey A. Mandal R. Sahai A. K. 《Theoretical and Applied Climatology》2022,147(1-2):205-215
Theoretical and Applied Climatology - In the seamless forecast paradigm, it is hypothesized that the reduction in initial error in the dynamical model forecast would help to reduce forecast error... 相似文献
14.
Prajapati V. K. Khanna M. Singh M. Kaur R. Sahoo R. N. Singh D. K. 《Theoretical and Applied Climatology》2022,149(1-2):207-220
Theoretical and Applied Climatology - This paper presents a composite approach for drought characterization and monitoring using in situ and remote sensing-based drought indicators. The study was... 相似文献
15.
Parampreet Kaur Naveen Chaudhri I. Raczek A. Kröner A.W. Hofmann M. Okrusch 《Gondwana Research》2011,19(4):1040-1053
The Khetri region forms a late Palaeoproterozoic igneous–metamorphic complex in NE Rajasthan, India. Seven granitoid plutons of the Khetri complex have been studied for zircon U–Pb and Pb–Pb dating along with whole-rock and Nd–Sr isotope geochemistry to provide new constraints on the Palaeoproterozoic magmatic activity in the Aravalli orogen of northwestern India. Most intrusives show evidence of moderate to extreme albitisation forming microcline–albite granite and albite granite, respectively. The rocks are metaluminous to weakly peraluminous, largely ferroan and intraplate A-type granites. The U–Pb zircon ages for four plutons cover a time span of 1732–1682 Ma, whereas Pb–Pb zircon evaporation data for three intrusives indicate minimum emplacement ages between 1671 and 1537 Ma. The Nd–Sr isotopic systematics suggest the involvement of Neoarchaean to Palaeoproterozoic crustal components in the petrogenesis of these granitoids. A regional survey of late Palaeoproterozoic ages in the Aravalli orogen provides evidence for a geographically widespread extension-related event in the northwestern Indian shield about 1720–1700 Ma ago. The record of comparable ages and the magmatic history reported in parts of North America and the North China Craton may indicate the significance of this event for the rift tectonics of the hypothetical supercontinent Columbia. 相似文献
16.
The geochemical investigation of sediments deposited in the Renuka Lake basin and its adjoining wetland has shown variation
in the distribution and concentration of major, trace and REEs. The major elements are depleted in the lake in relation to
wetland and that of Post Archaean Australian, Shale (PAAS), except for CaO which is strikingly in excess and has a dilution
effect on SiO2 and other oxides and trace elements. The Wetland sediments, on the other hand, are enriched in Al2O3, Fe2O3, K2O and TiO2 and the latter three show a positive correlation with Al2O3 in both wetland and lake sediments suggesting their association with phyllosilicates and similar source rocks. The enrichment
of Y, Zr, Ni, Th, U and Nb in wetland compared to lake and their similarity with PAAS in the former, suggests more clay fractions
in the wetland. A high Zr/Hf ratio in wetland and lake sediments and a positive correlation of Zr with Y and HREE indicate
Zr control on HREEs. However, higher Zr/Yb and Zr/Th ratios in wetland compared to lake indicate mineral sorting during the
process of lighter particles (clays) being trapped in wetland soil. This is also reflected from negative correlation of GdN/YbN with Al2O3 and a strong positive correlation with SiO2 in wetland sediments. The wetland in this context has a control on lake sediment chemistry. The chondrite normalized REE
patterns are essentially the same for lake as well as wetland sediments but abundance decreases in the former. The similarity
of pattern with that of PAAS and negative Eu anomaly indicates a cratonic source of sediments. In a plot of the individual
samples, wetland samples cluster while lake samples are separated indicating fractionation of lake sediments. A strong positive
correlation of LaN/YbN with Al2O3 and a positive correlation of Zr-∑LREE and Zr-LaN/YbN suggest that LREEs are controlled by both phyllosilicates and zircon. The chemical index of alteration (CIA) indices in lake
sediments and in wetland are higher than PAAS indicating moderate chemical weathering in the source area. The petrography,
lack of felsic magmatic rock fragments, and negative correlation between Zr-(Gd/Yb)C indicate sedimentary source rocks for the detritus. This is in conformity with the Lesser Himalayan sedimentary sequence
belonging to neo-Proterozoic–Proterozoic age and constituting lake catchment of Renuka. The tectonic delineation and discriminant
function plots of lake and wetland sediments indicate their cratonic and/or quartzose sedimentary orogenic terrain source
that has been deposited in a passive margin setting. 相似文献
17.
Clouds contribute significantly to the formation of many of the natural hazards. Hence cloud mapping and its classification
becomes a major component of the various physical models which are used for forecasting natural hazards. The problem of cloud
data classification from NOAA AVHRR (advance very high resolution radiometer) satellite imagery using image transformation
techniques is considered in this paper. The singular value decomposition (SVD) scheme is used to extract the salient spectral
and textural features attributed to satellite snow and cloud data in visible and IR channels. The goals of this paper are
to discriminate between clear sky and clouds in an 8 × 8 pixel array of 1.1 km AVHRR data. If clouds are present then classify
them as low, medium or high range. This scheme can effectively segregate clouds and non-cloud features in the visible and
IR bands of the imagery. It can also classify clouds as low, medium or high range with a success rate of 70–90%. Computer-based
snow and cloud discrimination and automatic cloud classification system will help the forecaster in various climatological
applications, viz., energy balance estimation, precipitation forecasting, landslide forecasting, weather forecasting and avalanche
forecasting etc. 相似文献
18.
Natural Hazards - Avalanche forecasting is carried out using physical as well as statistical models. All these models have certain limitations associated with their mathematical formulation that... 相似文献
19.
Prajapati V. K. Khanna M. Singh M. Kaur R. Sahoo R. N. Singh D. K. 《Natural Hazards》2021,109(1):89-109
Natural Hazards - The present study was carried out to characterize drought in the Marathwada region of Maharashtra, which experiences recurring droughts, through meteorological, hydrological and... 相似文献
20.
R. Kaur Rudy Wijnands Alessandro Patruno Vincenzo Testa GianLuca Israel Nathalie Degenaar Biswajit Paul Brijesh Kumar 《Monthly notices of the Royal Astronomical Society》2009,394(3):1597-1604
We present results from our Chandra and XMM–Newton observations of two low-luminosity X-ray pulsators SAX J1324.4−6200 and SAX J1452.8−5949 which have spin periods of 172 and 437 s, respectively. The XMM–Newton spectra for both sources can be fitted well with a simple power-law model of photon index, Γ∼ 1.0 . A blackbody model can equally well fit the spectra with a temperature, kT ∼ 2 keV, for both sources. During our XMM–Newton observations, SAX J1324.4−6200 is detected with coherent X-ray pulsations at a period of 172.86 ± 0.02 s while no pulsations with a pulse fraction greater than 18 per cent (at 95 per cent confidence level) in 0.2–12 keV energy band are detected in SAX J1452.8−5949 . The spin period of SAX J1324.4−6200 is found to be increasing on a time-scale of which would suggest that the accretor is a neutron star and not a white dwarf. Using subarcsec spatial resolution of the Chandra telescope, possible counterparts are seen for both sources in the near-infrared images obtained with the son of infrared spectrometer and array camera (SOFI) instrument on the New Technology Telescope. The X-ray and near-infrared properties of SAX J1324.4−6200 suggest it to be a persistent high-mass accreting X-ray pulsar at a distance ≤8 kpc . We identify the near-infrared counterpart of SAX J1452.8−5949 to be a late-type main-sequence star at a distance ≤10 kpc, thus ruling out SAX J1452.8−5949 to be a high-mass X-ray binary. However, with the present X-ray and near-infrared observations, we cannot make any further conclusive conclusion about the nature of SAX J1452.8−5949 . 相似文献