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71.
Mitigation of Iron Toxicity and Iron,Zinc, and Manganese Nutrition of Wetland Rice Cultivars (Oryza sativa L.) Grown in Iron‐Toxic Soil 下载免费PDF全文
72.
Rahul Tripathi Rabi N. Sahoo Vinay K. Sehgal R. K. Tomar Debashish Chakraborty S. Nagarajan 《Journal of the Indian Society of Remote Sensing》2012,40(1):19-28
The current development of satellite technology particularly in the sensors like POLDER and MISR, has emphasized more on directional
reflectance measurements (i.e. spectral reflectance of the target measured from different view zenith and azimuth angles)
of the earth surface features mainly the vegetation for retrieval of biophysical parameters at regional scale using radiative
transfer models. This approach being physical process based and uses directional reflectance measurement has been found to
better and more reliable compared to the conventional statistical approach used till date and takes care of anisotropic nature
(i.e. reflectance from the target is different if measured from different view angles) of the target. Keeping this in view
a field experiment was conducted in mustard crop to evaluate the radiative transfer model for biophysical parameter retrieval
through its inversion with the objectives set as (i) to relate canopy biophysical parameters and geometry to its bidirectional
reflectance, (ii) to evaluate a canopy reflectance model to best represent the radiative transfer within the canopy for its
inversion and (iii) to retrieve crop biophysical parameters through inversion of the model. Two varieties of the mustard crop
(Brassica juncea L) were grown with two nitrogen treatments. The bidirectional reflectance data obtained at 5 nm interval
for a range of 400–1100 nm were integrated to IRS LISS–II sensor’s four band values using Newton Cotes Integration technique.
Biophysical parameters like leaf area index, leaf chlorophyll content, leaf length, plant height and average leaf inclination
angle, biomass etc were estimated synchronizing with the bi-directional reflectance measurements. Radiative transfer model PROSAIL model was
validated and its inversion was done to retrieve LAI and ALA. Look Up Table (LUT) of Bidirectional reflectance distribution
function (BRDF) was prepared simulating through PROSAIL model varying only LAI (0.2 interval from 1.2 to 5.4 ) and ALA (5°
interval from 40° to 55°) parameters and inversion was done using a merit function and numerical optimization technique given
by Press et al. (1986). The derived LAI and ALA values from inversion were well matched with observed one with RMSE 0.521
and 5.57, respectively. 相似文献
73.
George Mathew Archana Nair T. K. Gundu Rao Kanchan Pande 《Journal of Earth System Science》2009,118(4):391-404
Thermal infrared spectroscopy is a powerful technique for the compositional analysis of geological materials. The spectral
feature in the mid-IR region is diagnostic of the mineralogy and spectral signatures of mixtures of minerals that add linearly,
and therefore, can be used as an important tool to determine the mineralogy of rocks in the laboratory and remotely for planetary
exploration. The greatest challenge in the emission measurement lies in the measurement of the weak thermal photons emitted
from geological materials in a laboratory setup, and accurately records the temperature of the rock sample. The present work
pertains to the details of a new Thermal Emission Spectrometer (TES) laboratory that has been developed under the ISRO Planetary
Science and Exploration (PLANEX) programme, for emission related mineralogical investigations of planetary surfaces. The focus
of the paper is on the acquisition and calibration technique for obtaining emissivity, and the deconvolution procedure to
obtain the modal abundances of the thermal emission spectra in the range of 6–25 μm using Fourier Transform Infrared (FTIR)
spectroscopy. The basic technique is adopted from the work of Ruff et al (1997). This laboratory at the Department of Earth Sciences, IIT-Bombay is currently developing pure end mineral library
of mineral particulates (<65 μm), and adding new end members to the existing ASU spectral library. The paper argues the need
for considering Lunar Orbiter Thermal Emission Spectrometer (LOTES) for future Indian Moon mission programme (Chandrayan-II)
to determine evidences of varied lithologies on the lunar surface. 相似文献
74.
Vijay S. Tripathi 《Geochimica et cosmochimica acta》1979,43(12):1989-1990
The necessity of considering protonation and complexation of weak acid ligands, for proper interpretation of their effect on solution equilibria, has been demonstrated. The solubility of uraninite in presence of σF = 2 ppm has been recalculated to be 0.88 ppb at pH 2. 相似文献
75.
The sapphirine granulites from G. Madugula, Eastern Ghats preserve a variety of mineral textures and reactions. Corona and
reaction textures are used in conjunction with mineral compositions to construct a sequence of metamorphic reactions describing
the mineralogical evolution of sapphirine granulites. An early stage is characterized by the development of sapphirine + quartz,
spinel + quartz in textural equilibrium, and possible relicts after osumilite during peak metamorphic conditions. Sapphirine/spinel
crystals were later detached from quartz in the form of mineral coronas. During a subsequent sapphirine-cordierite stage,
several cordierite forming reactions reflect decreasingP-T conditions. Finally during the late stage, a few samples show evidence of retrogressive hydration. Sapphirine is rather iron-rich
(12.8 wt%) and the Mg number in the analysed minerals varies in the order: cordierite > phlogopite > sapphirine > orthopyroxene
> spinel > garnet.P-T conditions of metamorphism have been constrained through the application of geothermobarometry and thermodynamically calibrated
MAS equilibria.P-T vectors from granulite facies rocks in the G. Madugula area indicate that the rocks experienced substantial decompression
(up to 3 kbar) and moderate cooling (150–200°C) subsequent to peak conditions of metamorphism (8.4 kbar, > 900°C). The decompressionalP-T history of sapphirine granulites interpreted from textural features and thermobarometric estimates suggest that they may
have eventually resulted from exhumation of thickened crust. 相似文献
76.
77.
Shivam Tripathi Rao S. Govindaraju 《Stochastic Environmental Research and Risk Assessment (SERRA)》2007,21(6):747-764
Recent advances in statistical learning theory have yielded tools that are improving our capabilities for analyzing large
and complex datasets. Among such tools, relevance vector machines (RVMs) are finding increasing applications in hydrology
because of (1) their excellent generalization properties, and (2) the probabilistic interpretation associated with this technique
that yields prediction uncertainty. RVMs combine the strengths of kernel-based methods and Bayesian theory to establish relationships
between a set of input vectors and a desired output. However, a bias–variance analysis of RVM estimates revealed that a careful
selection of kernel parameters is of paramount importance for achieving good performance from RVMs. In this study, several
analytic methods are presented for selection of kernel parameters. These methods rely on structural properties of the data
rather than expensive re-sampling approaches commonly used in RVM applications. An analytical expression for prediction risk
in leave-one-out cross validation is derived. For brevity, the effectiveness of the proposed methods is assessed first by
data generated from the benchmark sinc function, followed by an example involving estimation of hydraulic conductivity values
over a field based on observations. It is shown that a straightforward maximization of likelihood function can lead to misleading
results. The proposed methods are found to yield robust estimates of parameters for kernel functions. 相似文献
78.
S. Kasi Viswanath N. K. Tripathi K. R. Salin 《Journal of the Indian Society of Remote Sensing》2018,46(4):675-685
Chlorophyll-a (Chl-a) and Suspended Solid Concentration (SSC) shows the productivity of water and their surrounding environment. These parameters can be effectively estimated through several remote sensing techniques. From the recent reports on the Gulf of Thailand, it is found that Chl-a and SSC are increasing in coastal areas due to changing environment caused by variations in the global carbon cycle, climate change and water pollution linking to anthropogenic conditions such as high population density and rapid urbanization in neighbouring coastal areas deteriorating the coastal and marine environment. Various models are evaluated in this study for estimation of marine Chl-a and SSC by employing Ocean Colour Monitor-2 sensor of Oceansat-2 satellite for Northern Gulf of Thailand. The retrieval of Chl-a and SSC by the atmospheric correction of visible bands from 400 to 700 nm to attain normalized water-leaving radiances and then a suitable algorithm is applied. The In-situ reflectance values of sea waters are measured using the ASD spectroradiometer. The reflectance values of the spectroradiometer are correlated for the same day atmospherically corrected satellite reflectance and the analysis offers high correlation R2 0.73. Satellite derived, Chl-a and SSC are correlated with observed in situ Chl-a and SSC. This analysis offered better correlation of R2 0.86 and 0.85 respectively with the algorithms of Chl-a and SSC. 相似文献
79.
Pulakesh Das Mukunda Dev Behera Nitesh Patidar Bhabagrahi Sahoo Poonam Tripathi Priti Ranjan Behera S K Srivastava Partha Sarathi Roy Praveen Thakur S P Agrawal Y V N Krishnamurthy 《Journal of Earth System Science》2018,127(2):19
As a catchment phenomenon, land use and land cover change (LULCC) has a great role in influencing the hydrological cycle. In this study, decadal LULC maps of 1985, 1995, 2005 and predicted-2025 of the Subarnarekha, Brahmani, Baitarani, Mahanadi and Nagavali River basins of eastern India were analyzed in the framework of the variable infiltration capacity (VIC) macro scale hydrologic model to estimate their relative consequences. The model simulation showed a decrease in ET with 0.0276% during 1985–1995, but a slight increase with 0.0097% during 1995–2005. Conversely, runoff and base flow showed an overall increasing trend with 0.0319 and 0.0041% respectively during 1985–1995. In response to the predicted LULC in 2025, the VIC model simulation estimated reduction of ET with 0.0851% with an increase of runoff by 0.051%. Among the vegetation parameters, leaf area index (LAI) emerged as the most sensitive one to alter the simulated water balance. LULC alterations via deforestation, urbanization, cropland expansions led to reduced canopy cover for interception and transpiration that in turn contributed to overall decrease in ET and increase in runoff and base flow. This study reiterates changes in the hydrology due to LULCC, thereby providing useful inputs for integrated water resources management in the principle of sustained ecology. 相似文献
80.
Archana Soam 《天文和天体物理学研究(英文版)》2021,(4):79-89
In the work presented here,the impact of magnetic field on the dynamical evolution of cometary globules Sim 129 and Sim 130 in the Sh2-236 HⅡ region and the ionized gas streaming out of their surfaces is investigated.The magnetic field morphology in the region associated with these globules is inferred using optical polarization measurements with the Sampurnanand Telescope at ARIES.The nebular emission is probed through radio continuum mapping at 1.4 GHz with the archival National Radio Astronomy Observatory(NRAO) Very Large Array(VLA) Sky Survey(NVSS) data.The correlation of these measurements suggests that photoevaporated gas from the surfaces of Sim 129 and Sim 130 accumulates in clouds and starts streaming along the magnetic field lines.The ~(12)CO(J=1-0) molecular line observations are performed towards NGC 1893 from the 14-m single dish radio telescope in Taeduk Radio Astronomy Observatory(TRAO).The velocity dispersion in the ~(12)CO(J=1-0) molecular line and the dispersion in polarization angles are considered in the Davis-Chandrasekhar-Fermi formulation to estimate the magnetic field strength towards two Sim nebulae.The average value of field strength is found to be~60 μG with uncertainty of 0.5 times the estimated value. 相似文献