全文获取类型
收费全文 | 56篇 |
免费 | 0篇 |
专业分类
测绘学 | 12篇 |
大气科学 | 2篇 |
地球物理 | 4篇 |
地质学 | 20篇 |
海洋学 | 6篇 |
天文学 | 11篇 |
综合类 | 1篇 |
出版年
2021年 | 1篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 7篇 |
2014年 | 3篇 |
2013年 | 6篇 |
2012年 | 4篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 1篇 |
2007年 | 4篇 |
2006年 | 1篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有56条查询结果,搜索用时 62 毫秒
31.
D. Ganguly R. Ray N. Majumdar C. Chowdhury T. K. Jana 《Journal of Atmospheric Chemistry》2018,75(3):319-333
Temporal variations in atmospheric hydrogen sulphide concentrations and its biosphere-atmosphere exchanges were studied in the World’s largest mangrove ecosystem, Sundarbans, India. The results were used to understand the possible contribution of H2S fluxes in the formation of atmospheric aerosol of different size classes (e.g. accumulation, nucleation and coarse mode). The mixing ratio of hydrogen sulphide (H2S) over the Sundarban mangrove atmosphere was found maximum during the post-monsoon season (October to January) with a mean value of 0.59?±?0.02 ppb and the minimum during pre-monsoon (February to May) with a mean value of 0.26?±?0.01 ppb. This forest acted as a perennial source of H2S and the sediment-air emission flux ranged between 1213?±?276 μg S m?2 d?1(December) and 457?±?114 μg S m?2 d?1 (August) with an annual mean of 768?±?240 μg S m?2d?1. The total annual emissions of H2S from the Indian Sundarban were estimated to be 1.2?±?0.6 Tg S. The accumulation mode of aerosols was found to be more enriched with non-sea salt sulfate with an average loading of 5.74 μg m?3 followed by the coarse mode (5.18 μg m?3) and nucleation mode (1.18 μg m?3). However, the relative contribution of Non-sea salt sulfate aerosol to total sulfate aerosol was highest in the nucleation mode (83%) followed by the accumulation (73%) and coarse mode (58%). Significant positive relations between H2S flux and different modes of NSS indicated the likely link between H2S, a dominant precursor for the non-sea salt sulfate, and non-sea sulfate aerosol particles. An increase in H2S emissions from the mangrove could result in an increase in enhanced NSS in aerosol and associated cloud albedo, and a decrease in the amount of incoming solar radiation reaching the Sundarban mangrove forest. 相似文献
32.
S.K. Pal T.J. Majumdar Vipin Kumar Pathak Satya Narayan Ujjawal Kumar Om Prakash Goswami 《国际地球制图》2016,31(7):783-802
High-resolution EIGEN6C4 and EGM2008 Bouguer gravity data of 2190 degree spherical harmonic over the Singhbhum-Orissa Craton, India, have been generated from the International Centre for Global Earth Models. The Bouguer gravity anomaly difference maps of (i) in situ and EIGEN6C4, (ii) in situ and EGM2008 and iii) EIGEN6C4 and EGM2008 of the study area are compared. It reveals that EIGEN6C4 has lesser systematic error than EGM2008. However, from different profile plots of Bouguer gravity, east–west horizontal derivative and north–south horizontal derivative anomalies of the in situ, EIGEN6C4 and EGM2008, it is observed that most of the signatures of lithounits and geological structural elements are delineated very well by EGM2008 and match 94–98% with those of EIGEN6C4. Further, the Bouguer gravity, east–west horizontal derivative and north–south horizontal derivative anomalies of EGM2008 data over the study area have been used effectively for identifying various lithounits and geological structural elements. 相似文献
33.
34.
D. Bose V. R. Chitnis P. R. Vishwanath P. Majumdar M. A. Rahman B. B. Singh A. C. Gupta B. S. Acharya 《Astrophysics and Space Science》2007,309(1-4):111-117
We report our observations on 4 AGNs viz, Mkn 421, Mkn 501, 1ES1426+428 and ON231 belonging to a sub-class called blazars. The observations were carried out using the Pachmarhi Array of Cherenkov Telescopes and span about 6 years period from 2000 to 2005. We discuss our methods of analysis adopted to extract the gamma ray signal from cosmic ray background. We present our results on the emission of TeV gamma rays from these objects. Also, we report on the status of the new high altitude experiment, a 7 telescope array at Hanle in the Himalayas at an altitude of about 4200 m above mean sea level for detecting celestial gamma-rays. 相似文献
35.
T. J. Majumdar 《Natural Hazards》2013,69(1):729-747
Geological, geomorphological and tectonic element studies of the Kachchh region have been carried out and correlation between them with the seismic data has been attempted. Study and analysis of Bhuj region using various remote sensing techniques including surface temperature changes, InSAR studies and GPS have also been attempted to identify earthquake precursors on different scales and the areas susceptible to damage or disaster on different degrees. The Kachchh region is located in Mesozoic rift environment that was earlier characterized by tensional stresses, but present-day compressive stress regime suggests that this region is undergoing a stage of inversion tectonics. The present work aims at the application of remote sensing techniques in developing a long-term precursor in the form of landscape changes, before the occurrence of a major earthquake as a result of crustal stress accumulation. It is, therefore, necessary to find out with the help of other precursors whether or not the area is accumulating stress. A minute observation of all the acquired multi-temporal imageries could demarcate minute geomorphological changes in this region, for example, shifting of drainage patterns since the development of paleochannels, slow upliftment/depressions, etc. Moreover, a distinct change in temperature (~5 to 6 °C) could be observed on April 6, 2006, and again on April 10, 2006, in the Kachchh region before the occurrence of tremor, particularly along the Kachchh Mainland Fault, indicating that such tremor generates sufficient stress before the earthquake particularly along the fault line. b values study over the region during last 50 years has also clearly indicated the drastic stress changes particularly before the occurrence of a big earthquake. GPS observations have also indicated a major thrust region lying along ENE–WSW with stress alignment along ENE–WSW. The region on the west of the Kachchh Mainland Fault and the South Wagad Fault can be called as seismic gap region as very few major earthquakes have taken place in this region. 相似文献
36.
As more aquifer storage and recovery (ASR) systems are employed for management of water resources, the skillful operation of multiwell ASR systems has become very important to improve their performance. In this study, we developed MODFLOW and MT3DMS models to simulate a multiwell ASR system in a synthetic aquifer to assess effects of hydrogeological and operational factors on the performance of the multiwell ASR system. We evaluated a simplified (dual well) ASR system in comparison with complex system (three-, four-, five-, and seven-well systems). Recovery and energy efficiencies were calculated using the model simulations. Factors such as higher hydraulic conductivity and longitudinal dispersivity significantly reduced the recovery and energy efficiencies of the system. In contrast, increasing the volume of recharged water increased the recovery efficiency; however, the energy efficiency was reduced. Recovery and energy efficiencies also plummet when there is an increase in the underlying regional gradient and the designed storage duration. Operating the system multiple times can yield higher volume of potable water, but the energy efficiency may not vary significantly after the second operating cycle. Single-well systems and multiwell systems exhibit similar responses to changes in physical factors, although operational factors have a more pronounced effect on the multiwell systems. One of the major findings was that fewer wells in a multiwell ASR system can yield higher volume of potable water and better output with respect to the electrical power being consumed. The results provide design engineers with guidelines for optimizing performance of the multiwell ASR systems. 相似文献
37.
Susmita Majumdar D. R. C. Nair R. S. Saraswat A. Chandrasekar 《Journal of Earth System Science》1997,106(3):147-155
The explicit nonlinear normal mode initialization (ENMI) scheme is applied to a tropical barotropic limited area shallow water
model in spherical coordinates. The model is formulated by considering potential enstrophy conserving finite difference scheme.
It is seen from the results of this study that the ENMI scheme is fully capable of filtering out the spurious gravity wave
oscillations. The results are compared with those using an implicit nonlinear normal mode initialization (INMI). The latter
scheme gives equally satisfactory results, requiring less computational time than the explicit scheme. 相似文献
38.
D. Gopala Rao G. C. Bhattacharya M. V. Ramana V. Subrahmanyam T. Ramprasad K. S. Krishna A. K. Chaubey G. P. S. Murty K. Srinivas Maria Desa S. I. Reddy B. Ashalata C. Subrahmanyam G. S. Mital R. K. Drolia S. N. Rai S. K. Ghosh R. N. Singh R. Majumdar 《Marine Geophysical Researches》1995,17(3):321-322
39.
The Carlsberg Ridge lies between the equator and the Owen fracture zone. It is the most prominent mid-ocean ridge segment
of the western Indian Ocean, which contains a number of earthquake epicenters. Satellite altimetry can be used to infer subsurface
geological structures analogous to gravity anomaly maps generated through ship-borne survey. In this study, free-air gravity
and its 3D image have been generated over the Carlsberg Ridge using a very high resolution data base, as obtained from Geosat
GM, ERS-1, Seasat and TOPEX/POSEIDON altimeter data. As observed in this study, the Carlsberg Ridge shows a slow spreading
characteristic with a deep and wide graben (average width ∼15 km). The transform fault spacing confirms variable slow to intermediate
characteristics with first and second order discontinuities. The isostatically compensated region of the Carlsberg Ridge could
be demarcated with near zero contour values in the free-air gravity anomaly images over and along the Carlsberg Ridge axes
and over most of the fracture zone patterns. Few profiles have been generated across the Carlsberg Ridge and the characteristics
of slow/intermediate spreading ridge of various orders of discontinuity could be identified. It has also been observed in
zero contour image as well as in the characteristics of valley patterns along the ridge from NW to SE that different spreading
rates, from slow to intermediate, are occurring in different parts of the Carlsberg ridge. It maintains the morphology of
a slow spreading ridge in the NW, where the wide and deep axial valley (∼1.5–3 km) also implies the pattern of a slow spreading
ridge. However, a change in the morphology/depth of the axial valley from NW to SE indicates the nature of the Carlsberg Ridge
as a slow to intermediate spreading ridge.
For the prevailing security restrictions, lat./lon. coordinates have been omitted in few images. 相似文献
40.
S. K. Pal Satya Narayan T. J. Majumdar Ujjawal Kumar 《Marine Geophysical Researches》2016,37(3):159-184
A revised gravity anomaly map, generated from the EIGEN6C4 high resolution global gravity model, has been utilized for understanding structure and tectonics over the 85°E Ridge and surroundings. EIGEN6C4 data have been analysed using different derivatives and Analytical Signal techniques for delineation of structural features and comparative analysis with the published results, which shows good correlation. All the structural features observed in two seismic reflection sections over a small part of the 85°E Ridge have also been delineated very well. The lineament trends of N–S, NNW–SSE, ENE–WSW and E–W are consequences of the major changes occurred in the mid-Cretaceous towards the spreading trends from NNW–SSE to N–S and resulted in northward movement of the Indian Plate trailed by interaction with the Asian Plate in the Early Eocene. The lineaments in the eastern side of the ridge have greater circular variances and greater circular standard deviation than those of the western side, which reveals that the eastern side of the ridge has suffered more tectonic activities. 相似文献