全文获取类型
收费全文 | 90篇 |
免费 | 2篇 |
专业分类
测绘学 | 8篇 |
大气科学 | 14篇 |
地球物理 | 12篇 |
地质学 | 16篇 |
海洋学 | 1篇 |
天文学 | 41篇 |
出版年
2022年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 12篇 |
2012年 | 5篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 2篇 |
2006年 | 1篇 |
2005年 | 2篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 5篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有92条查询结果,搜索用时 15 毫秒
51.
Ramesh K. Kapoor B. B. Adiga S. P. Singal S. K. Aggarwal B. S. Gera 《Boundary-Layer Meteorology》1982,24(4):415-419
Observations made with a monostatic sodar and from a 120 m instrumented tower have been used to study the variations in the atmospheric boundary layer at Tarapur (19° 50 N, 72° 41 E) during the solar eclipse of February 16, 1980. Atmospheric instability was reduced below normal values during the eclipse but the atmosphere at no time became stable. 相似文献
52.
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
53.
Estimates of impact of climate change on crop production could be biased depending upon the uncertainties in climate change scenarios, region of study, crop models used for impact assessment and the level of management. This study reports the results of a study where the impact of various climate change scenarios has been assessed on grain yields of irrigated rice with two popular crop simulation models- Ceres-Rice and ORYZA1N at different levels of N management. The results showed that the direct effect of climate change on rice crops in different agroclimatic regions in India would always be positive irrespective of the various uncertainties. Rice yields increased between 1.0 and 16.8% in pessimistic scenarios of climate change depending upon the level of management and model used. These increases were between 3.5 and 33.8% in optimistic scenarios. At current as well as improved level of management, southern and western parts of India which currently have relatively lower temperatures compared to northern and eastern regions, are likely to show greater sensitivity in rice yields under climate change. The response to climate change is small at low N management compared to optimal management. The magnitude of this impact can be biased upto 32% depending on the uncertainty in climate change scenario, level of management and crop model used. These conclusions are highly dependent on the specific thresholds of phenology and photosynthesis to change in temperature used in the models. Caution is needed in using the impact assessment results made with the average simulated grain yields and mean changes in climatic parameters. 相似文献
54.
F. P. Keenan D. B. Jess K. M. Aggarwal R. J. Thomas J. W. Brosius J. M. Davila 《Monthly notices of the Royal Astronomical Society》2007,376(1):205-214
Recent fully relativistic calculations of radiative rates and electron impact excitation cross-sections for Fe xiii are used to generate emission-line ratios involving 3s2 3p2 –3s3p3 and 3s2 3p2 –3s2 3p3d transitions in the 170–225 and 235–450 Å wavelength ranges covered by the Solar Extreme-Ultraviolet Research Telescope and Spectrograph (SERTS). A comparison of these line ratios with SERTS active region observations from rocket flights in 1989 and 1995 reveals generally very good agreement between theory and experiment. Several new Fe xiii emission features are identified, at wavelengths of 203.79, 259.94, 288.56 and 290.81 Å. However, major discrepancies between theory and observation remain for several Fe xiii transitions, as previously found by Landi and others, which cannot be explained by blending. Errors in the adopted atomic data appear to be the most likely explanation, in particular for transitions which have 3s2 3p3d 1 D2 as their upper level. The most useful Fe xiii electron-density diagnostics in the SERTS spectral regions are assessed, in terms of the line pairs involved being (i) apparently free of atomic physics problems and blends, (ii) close in wavelength to reduce the effects of possible errors in the instrumental intensity calibration, and (iii) very sensitive to changes in N e over the range 108 –1011 cm−3 . It is concluded that the ratios which best satisfy these conditions are 200.03/202.04 and 203.17/202.04 for the 170–225 Å wavelength region, and 348.18/320.80, 348.18/368.16, 359.64/348.18 and 359.83/368.16 for 235–450 Å. 相似文献
55.
56.
River bank erosion hazard study of river Ganga,upstream of Farakka barrage using remote sensing and GIS 总被引:1,自引:0,他引:1
This study has been carried out to analyze and report the river bank erosion hazard due to morphometric change of the Ganga
River (also called Ganges in English) in the upstream of Farakka Barrage up to Rajmahal. Morphometric parameters, such as,
Sinuosity, Braidedness Index, and percentage of the island area to the total river reach area were measured for the year of
1955, 1977, 1990, 2001, 2003, and 2005 from LANDSAT and IRS satellite images. The analysis shows that there is a drastic increase
in all of those parameters over the period of time. This study has found that bank failure is because of certain factors like
soil stratification of the river bank, presence of hard rocky area (Rajmahal), high load of sediment and difficulty of dredging
and construction of Farakka Barrage as an obstruction to the natural river flow. For the increasing sinuosity, the river has
been engulfing the large areas of left bank every year. The victims are mostly Manikchak and Kaliachak-II blocks of Malda
district, with a loss of around 1,670 ha agricultural land since 1977. Temporal shift measurements for the river reach between
Farakka and Rajmahal has been done with help of 22 cross-sections in this reach. Erosion impact area has also been estimated
to emphasize the devastating nature of the hazard. 相似文献
57.
B. S. Chaudhary Sandeep Aggarwal 《Journal of the Indian Society of Remote Sensing》2009,37(2):251-260
Present study deals with the demarcation of palaeochannels and mapping of integrated water resources in parts of Hisar district,
Haryana using Indian Remote Sensing Satellite (IRS-1D) LISS-III Data of December 21, 2001. The landforms identified are Sand
Dune, Dune Complex, Aeolian Plain, Fluvioaeolian plain, Palaeochannel and Younger Alluvial Plain formed by aeolian, fluvio-aeolian,
and fluvial processes. These palaeochannels are first time demarcated in the area. The ground water prospects of various geomorphic
units have been assessed. Depth to water level and ground water quality maps were digitized and put in to GIS format. Ground
water prospects and quality maps were integrated and depth to water level information was draped on it to prepare final integrated
ground water resources map. This map depicts ground water prospects, quality and depth together in a single map, which will
help in and ground water exploration. 相似文献
58.
S. S. Aggarwal 《Astrophysics and Space Science》1975,33(2):259-264
The electromagnetic instability in collisionless, anisotropic magnetized plasma contrastreams for perturbations propagating normally to the ambient magnetic field is investigated. It is found that the parallel temperature stabilizes the configuration forT ‖≤T ⊥ while it shows destabilizing effect forT ‖>T ⊥. A comparative study of the growth rates associated with various coexisting modes reveals that the electromagnetic instability may, under certain conditions, be associated with larger growth rates than the electrostatic instability. 相似文献
59.
Land‐cover/climate changes and their impacts on hydrological processes are of widespread concern and a great challenge to researchers and policy makers. Kejie Watershed in the Salween River Basin in Yunnan, south‐west China, has been reforested extensively during the past two decades. In terms of climate change, there has been a marked increase in temperature. The impact of these changes on hydrological processes required investigation: hence, this paper assesses aspects of changes in land cover and climate. The response of hydrological processes to land‐cover/climate changes was examined using the Soil and Water Assessment Tool (SWAT) and impacts of single factor, land‐use/climate change on hydrological processes were differentiated. Land‐cover maps revealed extensive reforestation at the expense of grassland, cropland, and barren land. A significant monotonic trend and noticeable changes had occurred in annual temperature over the long term. Long‐term changes in annual rainfall and streamflow were weak; and changes in monthly rainfall (May, June, July, and September) were apparent. Hydrological simulations showed that the impact of climate change on surface water, baseflow, and streamflow was offset by the impact of land‐cover change. Seasonal variation in streamflow was influenced by seasonal variation in rainfall. The earlier onset of monsoon and the variability of rainfall resulted in extreme monthly streamflow. Land‐cover change played a dominant role in mean annual values; seasonal variation in surface water and streamflow was influenced mainly by seasonal variation in rainfall; and land‐cover change played a regulating role in this. Surface water is more sensitive to land‐cover change and climate change: an increase in surface water in September and May due to increased rainfall was offset by a decrease in surface water due to land‐cover change. A decrease in baseflow caused by changes in rainfall and temperature was offset by an increase in baseflow due to land‐cover change. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
60.
In this problem, one of the primaries of mass \(m^{*}_{1}\) is a rigid spherical shell filled with a homogeneous incompressible fluid of density ρ 1. The smaller primary of mass m 2 is an oblate body outside the shell. The third and the fourth bodies (of mass m 3 and m 4 respectively) are small solid spheres of density ρ 3 and ρ 4 respectively inside the shell, with the assumption that the mass and the radius of the third and the fourth body are infinitesimal. We assume that m 2 is describing a circle around \(m^{*}_{1}\) . The masses m 3 and m 4 mutually attract each other, do not influence the motions of \(m^{*}_{1}\) and m 2 but are influenced by them. We also assume that masses m 3 and m 4 are moving in the plane of motion of mass m 2. In the paper, equilibrium solutions of m 3 and m 4 and their linear stability are analyzed. There are two collinear equilibrium solutions for the system. The non collinear equilibrium solutions exist only when ρ 3=ρ 4. There exist an infinite number of non collinear equilibrium solutions of the system, provided they lie inside the spherical shell. In a system where the primaries are considered as earth-moon and m 3,m 4 as submarines, the collinear equilibrium solutions thus obtained are unstable for the mass parameters μ,μ 3,μ 4 and oblateness factor A. In this particular case there are no non-collinear equilibrium solutions of the system. 相似文献