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41.
Mitigation of Iron Toxicity and Iron,Zinc, and Manganese Nutrition of Wetland Rice Cultivars (Oryza sativa L.) Grown in Iron‐Toxic Soil
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Geochemical fractionation of heavy metals in Chilka Lake (east coast of India)—a tropical coastal lagoon 总被引:1,自引:0,他引:1
Chilka lake, the largest coastal lagoon of Asia is one of the most dynamic ecosystems along the Indian coast. Historically the lagoon has undergone a considerable reduction in surface area due, in part, to input from natural processes but mostly due to human activities. The purpose of this investigation is to document the heavy metals' affinity for specific geochemical phases in the recently deposited sediments in the lagoon. Thirty-three samples were collected and analyzed for different geochemical phases of Fe, Mn, Cu, Cr, Ni, Pb, and Zn utilizing a sequential extraction scheme. In the nonlithogenous fraction, the exchangeable fraction was not geochemically significant, having <2% of the total metal concentration for all the elements. However, the carbonate fraction contained the following percentages of the total concentration: <1% Fe, 13% Mn, 6% Cu, 4% Cr, 8% Ni, 13% Pb, and 12% Zn, suggesting the detrital origin of the sediments. Reducible and organic matter-bound fractions were the significant phases in the nonlithogenous fraction, containing 9% Fe, 16% Mn, 15% Cu, 16% Cr, 16% Ni, 14% Pb, and 14% Zn in the former and 4% Fe, 3% Mn, 17% Cu, 3% Cr, 14% Ni, 15% Pb, and 14% Zn in the latter. The phenomenon has been attributed to the scavenging affinity of Fe-Mn oxides and affinity for sorption into organic matter of the lagoon sediments. The lithogenous, residual fraction generally considered as a guide for natural background values was determined to contain 87% Fe, 67% Mn, 61% Cu, 77% Cr, 61.3% Ni, 56% Pb, and 60% Zn of the total concentrations. 相似文献
44.
V. K. Pandey S. N. Panda N. S. Raghuwanshi S. Sudhakar 《Journal of the Indian Society of Remote Sensing》2006,34(2):143-152
Delineation of Banikdih Agricultural watershed in Eastern India was carried out and various watershed parameters were extracted
using Geographic Information System (GIS) and Remote Sensing. Digital Elevation Model (DEM) was developed with a contour interval
of 10 m in the scale of 1:25000 using ARC/INFO modules. Sub watershed, drainage, slope, aspect, flow direction, soil series,
soil texture, and soil class maps were independently generated and they were properly registered and integrated for analysis.
The watershed was digitally delineated using AVSWAT model that couples hydrological model and GIS with appropriate threshold
value of cell size. Subsequently, stream characteristics through the interface were generated. Indian Remote Sensing Satellite
IRS-1D LISS-III data pertaining to the period of October 29, 1998 and October 23, 2000 was used to develop land use/land cover
thematic map using ERDAS- 8.4 version image processing software. Eight major land use/land cover classes namely water body,
lowland paddy, upland paddy, fallow land, upland crop (non-paddy crops), settlement, open mixed forest, and wasteland were
segregated through digital image processing techniques using maximum likelihood algorithm. The information generated would
be of immense help in hydrological modeling of watershed for prediction of runoff and sediment yield, thereby providing necessary
inputs for developing suitable developmental management plans with sound scientific basis. 相似文献
45.
S.?K.?Dash K.?C.?PattnayakEmail author S.?K.?Panda Deepika?Vaddi Ashu?Mamgain 《Climate Dynamics》2015,44(3-4):961-975
In this study, a smaller domain over India alone and a larger South Asia (SA) domain have been used in the Regional Climate Model version 4.2 (RegCM4.2) to examine the effect of the domain size on the Indian summer monsoon simulations. These simulations were carried out over a period of 36 years at 50 km horizontal resolution with the lateral boundary forcings of the UK Met Office Hadley Centre Global Circulation Model Version 2.0. Results show that the Indian summer monsoon rainfall is significantly reduced when the domain size for the model integration is reduced from SA to the Indian domain. In case of SA domain simulation, the Equitable Threat Scores have higher values in case of very light, light and moderate rainfall events than those in case of the Indian domain simulation. It is also found that the domain size of model integration has dominant impact on the simulated convective precipitation. The cross-equatorial flow and the Somali Jet are better represented in the SA simulation than those in the Indian domain simulation. The vertically integrated moisture flux over the Arabian Sea in the SA domain simulation is close to that in the NCEP/NCAR reanalysis while it is underestimated in the Indian domain simulation. It is important to note that when RegCM4.2 is integrated over the smaller Indian domain, the effects of the Himalayas and the moisture advection from the Indian seas are not properly represented in the model simulation and hence the monsoon circulation and associated rainfall are underestimated over India. 相似文献
46.
Natural Hazards - Flooding events in the Lower Benue valley of Nigeria are often associated with huge damage to properties and loss of life in the adjoining communities. Specific objectives of this... 相似文献
47.
Iwan models are used to simulate the non-linear and hysteretic behaviour of soils under cyclic loading conditions. However, the model in its original form cannot take into account the stiffness degradation which is observed during cyclic loading of soft clays. Studies show that the stiffness reduction (expressed as degradation index) can be represented as a function of the number of cycles and of a degradation parameter depending on the strain amplitude in the case of strain controlled cyclic loading tests. This degradation index has been incorporated into Iwan's series–parallel model as a single fatigue parameter to account for the degradation during cyclic loading. The comparisons made with the existing results of two marine clays tested under undrained cyclic triaxial and simple shear conditions provided an opportunity to understand the capability of the one dimensional model. 相似文献
48.
49.
P. Mishra S. K. Patra M. V. Ramana Murthy P. K. Mohanty U. S. Panda 《Natural Hazards》2011,59(2):1145-1159
A 97-day-long record on waves and currents was obtained using wave rider buoy and current meter moored at 2.5 km off Gopalpur
from 19 May to 23 August 2008 representing southwest monsoon months. A Valeport tide gauge was used to record water level
at Gopalpur port. Simultaneously, beach profiles at 4 transects were monitored using real-time kinematic (RTK) global positioning
system (GPS). A total of 636,167 waves were analyzed for the period; a range of 3,200–9,700 waves approach the coast in an
individual day. During the study, unusual characteristics of wave were observed on July 29, 2008, with a magnitude of significant
wave height, Hs = 2.85 m, maximum wave height, Hmax = 5.22 m, and peak wave period, Tp = 10.2 s, and on August 11, 2008, with Hs = 2.28 m, Hmax = 5.37 m, and Tp = 11.1 s. Significant beach loss was noticed during these periods, and severe erosion was recorded on August 1, 2008. Beach
profile data indicates that 18–58 cu. m/m sediment was lost during the study period. The paper provides an overview of the
statistical analysis of wave heights, periods, direction, and spectral energy density and explains the cause of coastal erosion
and loss of sediment. 相似文献
50.
Characterizing spatial variability of soil properties in salt affected coastal India using geostatistics and kriging 总被引:2,自引:0,他引:2