全文获取类型
收费全文 | 72篇 |
免费 | 1篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 24篇 |
地球物理 | 11篇 |
地质学 | 26篇 |
海洋学 | 5篇 |
天文学 | 3篇 |
自然地理 | 3篇 |
出版年
2022年 | 1篇 |
2019年 | 1篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 3篇 |
2013年 | 5篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 3篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1987年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有73条查询结果,搜索用时 421 毫秒
61.
Parameterization of sea surface drag under varying sea state and its dependence on wave age 总被引:1,自引:0,他引:1
R. Rajesh Kumar B. Prasad Kumar A. N. V. Satyanarayana D. Bala Subrahamanyam A. D. Rao S. K. Dube 《Natural Hazards》2009,49(2):187-197
Momentum and energy exchange at air–sea interface through wind stress is very important for air–sea interaction studies, ocean
modeling, and climate studies. The accurate representation of wind stress, in terms of drag coefficient, is a key factor in
estimating the momentum transfer at the interface. The drag coefficient, in general, estimated using bulk formulae does not
take into account the influence of wave age. This study examines the dependence of wave age on computed surface drag coefficient
obtained by combining the Toba 3/2-power law with Froude number scaling, resulting in a new drag formulation (hereafter referred
as RP formulation). We demonstrate that our proposed formulation is in good conjunction with established theories for both
young and mature waves. Our investigation shows the theoretical formulation advocated earlier by Guan and Xie (hereafter referred
as GX) overestimated the surface drag for mature waves as wind speed tends to increase. In addition, the formulation by GX
was not verified by observational data. In the present work, for validation purpose, we use time series measurement of meteorological
and oceanographic data from a deep water location in the Indian Ocean which was tested with both RP and GX formulations. We
find that the proposed RP formulation, which embeds the 3/2 power of wave-age, shows a better match for both young and mature
waves with the results of Janssen compared to the hypothesis of conventional wave age used by GX. 相似文献
62.
We discuss the impact of the differential treatment of the roughness lengths for momentum and heat ( $z_{0\mathrm{m}}$ and $z_{0\mathrm{h}}$ ) in the flux parametrization scheme of the high-resolution regional model (HRM) for a heterogeneous terrain centred around Thiruvananthapuram, India (8.5°N, 76.9°E). The magnitudes of sensible heat flux (H) obtained from HRM simulations using the original parametrization scheme differed drastically from the concurrent in situ observations. With a view to improving the performance of this parametrization scheme, two distinct modifications are incorporated: (1) In the first method, a constant value of 100 is assigned to the $z_{0\mathrm{m}}/z_{0\mathrm{h}}$ ratio; (2) and in the second approach, this ratio is treated as a function of time. Both these modifications in the HRM model showed significant improvements in the H simulations for Thiruvananthapuram and its adjoining regions. Results obtained from the present study provide a first-ever comparison of H simulations using the modified parametrization scheme in the HRM model with in situ observations for the Indian coastal region, and suggest a differential treatment of $z_{0\mathrm{m}}$ and $z_{0\mathrm{h}}$ in the flux parametrization scheme. 相似文献
63.
Evapotranspiration (ET) is a vital process in land surface atmosphere research. In this study, Surface Energy Balance Algorithm for Land (SEBAL) for the assessment of ET (for 23 December 2010, 8 January 2011, 24 January 2011, 9 February 2011, 25 February 2011, 29 March 2011 and 14 April 2011) from LANDSAT7-ETM+ and validation with Lysimeter data set is illustrated. It is based on the evaporative fraction concept, and it has been applied to LANDSAT7-ETM + (30 m resolution) data acquired over the Indian Agricultural Research Institute’s agricultural farm land. The ET from SEBAL was compared with Lysimeter ET using four statistical tests (root-mean-square error (RMSE), relative root-mean-square error (R-RMSE), mean absolute error (MAE), and normalized root-mean square error (NRMSE)), and each test showed a good correlation between the predicted and observed ET values. Results from this study revealed that the RMSE of crop-growing period was 0.51 mm d?1 for ETSEBAL, i.e. ETSEBAL having good accuracy with respect to observed ETLysimeter. Results were also validated using R-RMSE test, which also proved that ETSEBAL data are having good accuracy with respect to observed ETLysimeter as R-RMSE of crop-growing period is 0.19 mm d?1. MAE (0.19), NRMSE (0.21) and r2 (0.91) tests indicated that model prediction is significant, and model can be effectively used for the estimation of ET from SEBAL as input of remote sensing data sets. Finally, the SEBAL has been useful for remote agricultural land where ground-based data (Lysimeter data) are not available for daily ET (ET24 h) estimation. The temporal study of the ET24 h values analysed has revealed that the highest ET24 h values are owing to the higher development (high greenness) of crops, whereas the lower values are related to the lower development (low greenness) or null crop. 相似文献
64.
Raj Bala 《Geoforum》1982,13(3):257-262
This paper deals with the mode of emergence, population size, functional nature and distributional pattern of new towns in India as recorded at the 1971 Census. It was discovered that (i) an overwhelming majority of new towns were not new settlements but expanded villages. The rest owed their status to one of four situations: an independent town is carved out of an existing urban place; neighbouring towns are merged into a new unit; a declassified town in 1961 gets reclassified in 1971; and a new town is built, usually on planned lines; (ii) mode of emergence was the most vital factor in determining demographic attributes; (iii) new towns represented two contrasting tendencies in Indian urbanisation: concentrated urbanisation around metropolitan nodes and dispersed urbanisation in recently developing backward regions. 相似文献
65.
D.?Bala SubrahamanyamEmail author T.?J.?Anurose Mannil?Mohan M.?Santosh N.?V.?P.?Kiran Kumar S.?Sijikumar 《Pure and Applied Geophysics》2012,169(4):741-753
On 15 January 2010, Thumba (8.5°N, 76.9°E) witnessed one of the longest known noontime annular solar eclipses (ASEs) spanning
a period of about 7 min, centered at 1314 hours local time. In this research article, we present a case study on the behaviour
of the atmospheric boundary layer characteristics and its vertical structure in response to this rare celestial event by making
use of a suite of different in-situ instruments. During the peak period of the ASE, the incoming solar irradiance was dimmed
by about 87% of its normal values, resulting in a significant reduction in the magnitudes of turbulent kinetic energy and
surface-layer turbulent fluxes of heat and momentum. The intensity and vertical thickness of the sea/land breeze circulation
cell over the study domain also weakened. However, the mixed layer heights determined from balloon-borne GPS Radiosonde did
not show any appreciable changes. Analysis of vertical profiles of thermodynamic parameters in association with the wind direction
during ASE indicated the formation of a double mixed layer between 700 and 1500 m and is attributed to horizontal advection
of a different airmass at those altitudes. 相似文献
66.
Groundwater extraction is rampant in many developing countries and urban areas whereas the natural recharge is decreasing due to covering of Earth's surface for various developmental activities. This leads to declining levels of groundwater and deterioration in groundwater quality. Artificial recharge with rain water harvesting techniques offers an excellent scope to arrest this degradation. This paper presents a study that analyzes the influence of rain water harvesting (RWH) on groundwater storage and quality. Chennai City, India is selected as study area, as major RWH implementation has taken place during 2002–2003 due to Government legislation. Preliminary analysis of groundwater levels were done spatially and temporally. Groundwater table contours were drawn using the GIS software for pre‐ (1999–2000) and post‐RWH (2009–2010) periods. The groundwater levels follow a decreasing trend before implementation of RWH where as a positive increasing trend takes place after construction of RWH structures. “Groundwater Estimation Committee (GEC)” norms of Government of India were used to estimate the change in storage during pre‐ and post‐RWH periods, which are found to be 1.76 × 106 and 32.77 × 106 m3, respectively. The results show that the implementation of RWH has increased the groundwater storage considerably. Also, the influence of RWH on groundwater quality is found to be encouraging in some parts of the studied area. 相似文献
67.
Subrahamanyam D. Bala Ramachandran Radhika Nalini K. Paul Freddy P. Roshny S. 《Natural Hazards》2019,96(1):431-459
Natural Hazards - In the first week of December 2017, a very severe cyclonic storm, namely “OCKHI”, made its landfall over the western coastline of the Indian peninsula. In a... 相似文献
68.
Andrei Bala Bogdan Grecu Viorica Ciugudean Victor Raileanu 《Soil Dynamics and Earthquake Engineering》2009
Bucharest is one of the cities most affected by earthquakes in Europe. Situated at 150–170 km distance from Vrancea epicentral zone, Bucharest had suffered many damages due to high energy Vrancea intermediate-depth earthquakes. For example, the 4 March 1977 event produced the collapse of 32 buildings with 8–12 levels, while more than 150 old buildings with 6–9 levels were seriously damaged. The studies done after this earthquake had shown the importance of the surface geological structure upon ground motion parameters. New seismic measurements are performed in Bucharest area aiming at defining better elastic and dynamic properties of the shallow sedimentary rocks. Down-hole seismic measurements were performed in a number of 10 cased boreholes drilled in the Bucharest City area. Processing and interpretation of the data lead to the conclusion that shallow sedimentary rocks can be considered weak in the area, down to 150–200 m depth. Seismic wave velocity values and bulk density values presented in the paper associated with local geology are useful primary data in the seismic microzonation of Bucharest City. They are used as 1D models to derive transfer functions and response spectra for the stack of sedimentary rocks in several parts of Bucharest area, leading to a better knowledge of the local site amplification and associated frequency spectra. In a recent study the H/V spectral ratio using Nakamura’s method was applied on the seismic noise measurements in 22 sites in Bucharest City in order to derive the fundamental period associated with these sites. The values confirm the previous results, showing a dominant resonance in the period range of 1.25–1.75 s. The fundamental periods obtained with Nakamura’s method are in good agreement with those computed on the basis of geological and geotechnical data in boreholes, which show an increase of the fundamental period in the Bucharest area from south to north, in the same direction as the increase of the thickness of the Quaternary deposits above the Fratesti layer which is considered the bedrock in the area. 相似文献
69.
70.
Jadwiga A. Jarzyna Maria J. Bala Zofia M. Mortimer Edyta Puskarczyk 《Geophysical Prospecting》2013,61(5):1006-1021
A methodology for rock classification is presented that considers lithology and reservoir parameters on the basis of a combined fractal analysis of well logs and mercury porosimetry results with nuclear magnetic resonance outcomes. A sandy‐shaly thinly‐bedded Miocene gas bearing formation in the Carpathian Foredeep is investigated. Fractal correlation dimensions D2 calculated for standard logs are used to distinguish sandstone as the most homogeneous lithological group with the highest porosity. The fractal analysis also confirmed observations of gas accumulations in sandstone, shaly sandstone and sandy claystone as rocks of high porosity. The results of two laboratory methods are combined to improve reservoir properties assessment and evaluate movable media in pore space; this technique was based on the similarity of mercury porosimetry results plotted as cumulative intrusion volume versus pressure or pore diameter and also the curves of cumulative porosity and transverse relaxation time distributions using nuclear magnetic resonance. Close values of porosity from logs, recorded in situ and in laboratory measurements, provide the link between fractal analysis and porosimetry and nuclear magnetic resonance measurements. 相似文献