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51.
Surajit Ghosh Praveen Kumar Thakur Vaibhav Garg Subrata Nandy Shivprasad Aggarwal 《Marine Geodesy》2015,38(3):597-613
In the present study, behavior of the SARAL/AltiKa (Satellite with ARgos and ALtiKa) waveforms over Maithon Reservoir (~65 km2 of surface area), Jharkhand, India, has been studied. The estimated water level has been compared with the in situ measurements at hydro-gauging station at the dam site. The problem of minimization of errors in the water level retrieval from AltiKa measurements has been resolved by improvement of the retracking method. A real retracking gate detection algorithm based on statistical analysis harnessing various physical parameters of the waveform has been developed, which has been applied to SARAL/AltiKa waveforms over the Maithon reservoir. Comparing the in-situ measurements with altimetry data (from cycle 1, 19 March 2013 to cycle 12, 8 April 2014) showed that it is crucial to improve the retracking method. Results showed accuracy of water level monitoring increased by nearly 76% by the newly developed waveform retracking algorithm over non-retracked water level. We also compared this new method with the existing ice-1 algorithm and found that with the new method there is improvement of ~27% over ice-1 retracked water level. The correlation coefficient values and root mean square values without retracking, with ice-1 algorithm and with newly developed retracking algorithm were 0.87, 0.91, and 0.95, and 8.12 cm, 2.08 cm, and 1.42 cm, respectively. This shows the proposed retracker performed better than ice-1. The retracking procedure helped in outliers' identification and substitution and with waveform fitting and waveform parameter extraction. This algorithm should have good performance capability for retrieving water level over inland water bodies like Maithon reservoir. 相似文献
52.
S. C. Patel S. Ravi S. S. Thakur T. K. Rao K. V. Subbarao 《Mineralogy and Petrology》2006,88(1-2):363-380
Summary Mineralogical characteristics of eclogite xenoliths from three kimberlite pipes (KL2, P2 and P10) of the Proterozoic Wajrakarur
kimberlite field of southern India have been studied. In a rare sample of enstatite eclogite from the KL2 pipe garnet contains
microscopic triangular arrays of needles or blebs of omphacite, enstatite and rutile consistent with an origin by exsolution
parallel to the isometric form {111}. Discrete omphacite grains in the sample contain exsolved needles or blebs of enstatite
and garnet. Kyanite eclogites are abundant in the KL2 pipe which occasionally show a secondary ring of pure celsian around
kyanite grains. Omphacite Na2O contents in the eclogites of the KL2 and P2 pipes are typically between 3 and 6 wt%, and garnet has widely variable composition
with end member ranges of Prp22-81Grs0-47Alm10-30Sps0-1Adr0-5Uv0-3. Eclogites of the P10 pipe comprise chromian omphacite
and garnet. Phase relations in the ACF projection exhibit systematic increase of the Ca-Tschermak’s component in omphacite
from enstatite eclogite through biminerallic eclogite to kyanite eclogite. Garnet-clinopyroxene Fe–Mg geothermometry yields
temperatures mostly in the range of 900–1100 °C. A formerly supersilicic nature of garnet in enstatite eclogite as inferred
from exsolution mineralogy indicates minimum peak pressure of 5 GPa. 相似文献
53.
N. D. Sharma R. Thakur G. L. Kippa B. Marak 《Journal of the Indian Society of Remote Sensing》1984,12(2):1-11
The aerial remote sensing data can be reliable source to obtain an estimate of urban population. A study was carried out in the city of Coimbatore (municipal area) using aerial photoghraphs of scale 1:4000 taken by a metric camera of 300 mm. focal length in the year 1979. The findings obtained by photo-interpretation compared very favourably with the interpolated population census figures for the year 1979, for the municipal area of the city Coimbatore. Dwelling units counted on the aerial photograph for different types of residential areas classified on the basis of size, shape and pattern are the physical indicators of population. Occupancy rate of dwelling units was determined by sampling survey carried out during field visit itself in this particular study. 相似文献
54.
Abundance ratios in QSOs Q 1246-057, 0453-423, PKS 0528-250, Q 0002-422, and PKS 2126-158 have been calculated by the method of curve of growth. Relative abundance of carbon with respect to silicon has been calculated in the QSOs Q 1246-057, PKS 0528-250, Q 0002-422, and PKS 2126-158. Relative abundance of aluminium with respect to silicon has been calculated in the QSOs PKS 0528-250 and PKS 2126-158. Relative abundance of iron with respect to magnesium has been also calculated in the QSOs Q 0453-423 and Q 0002-422. The ratiosN(C)/N(Si) andN(Al)/N(Si) andN(Fe)/N(Mg) in QSOs considered as a class are 3.45±2.33, 0.063±0.054, and 1.08±0.70, respectively.The ratiosN(C)/N(Si) andN(Al)/N(Si) show a mild trend of increase with decreasing emission redshift. On the other hand, the ratioN(Fe)/N(Mg) shows a mild trend of decrease with decreasing emission redshift. This suggests the possibility of the chemical evolution of QSOs.The comparison ofN(C)/N(Si), the relative abundance of carbon-one of the four most plentiful elements — with respect to silicon in QSOs and normal galaxies suggests that QSOs might belong to an early phase in the evolutionary sequence of galaxies and that they evolve chemically into normal galaxies in course of time.Mrs. Alpana Gangopadhyaya after marriage. 相似文献
55.
Sutirtha Thakur 《国际地球制图》2019,34(5):528-538
This study presents a novel contrast-based classification algorithm for Synthetic Aperture Radar image. The proposed algorithm primarily analyses homogeneous and non-homogeneous patterns within the moving window. The points which are either significantly brighter or darker than the central pixel are considered as non-homogeneous patterns. While the points, moderately equal to central pixel are described as homogeneous patterns. The mean intensity values of homogeneous and non-homogeneous regions are used thereafter for measuring the contrast around the central pixel of the moving window. The ISODATA algorithm is used to classify the contrast transformed image. The importance of this method is that it is computationally simple, works with minimum human interaction and robust to speckle noise. The validation of the method is done on RISAT (Radar Imaging Satellite) data. 相似文献
56.
Sponges alter the proportion of structural and morphological components such as spicule skeleton and number of oscula in response to environment, development and growth. Such mechanisms indicate morphological and physiological variations within populations. We measured the pumping rate of different sized specimens of contractile sponge Cinachyrella cf. cavernosa present in the intertidal rock pools, during morning and afternoon low tides along the central west coast of India. Additionally, we measured the exhalant opening (oscular cross‐sectional area—OSA), tissue density, spicule skeleton weight and the abundance of choanocyte chambers to assess the morphological variations. Water temperature and sponge size showed a significant positive effect on pumping rate. OSA and the number of oscula increased with sponge size, but the sponge volume‐specific pumping rate did not increase (0.029 ± 0.020 ml/s ml‐1). Histological sections showed the abundance of chaonocyte chambers increased marginally with the sponge size, but the contraction state affected the count. Both tissue density and spicule skeleton weight were positively correlated with sponge size, particularly the increase in the size and number of spicule bundles radiating from the centre indicated a denser core in larger specimens. The subcortical lacunae and the peripheral choanosome with high abundance of canals appear to be the major volume reduction zones during contraction events. Our results indicate that the size and number of spicule bundles increase with sponge volume and the variation in temperature, contraction state, and size and number of oscula influence the pumping rate of C. cf. cavernosa. 相似文献
57.
58.
In the hilly region due to scarcity of the plain area, buildings like set back-step back are more often used and also as a big surge in the telecommunication industries, rooftop tower adaptation is very common story nowadays. In the present study an analogy has been drawn to find out the influence of the rooftop telecommunication tower on the setback-step back building resting on ground at 20° and 30° slopes. A dynamic analysis has been performed and compared on the 4 legged angled section telecommunication tower which is located on the roof top of set back-step back building by varying positions of tower with the existing host structure built up on ground slope of 20° and 30° in both directions(X and Y). 相似文献
59.
S. V. N. Rao Sudhir Kumar Shashank Shekhar S. K. Sinha S. Manju 《Hydrogeology Journal》2007,15(6):1157-1167
This report examines the problem involving the pumping of groundwater from a group of 90 existing wells along the banks of the Yamuna River, northwest of Delhi (India), underlain with geologically occurring saline water. It is known that unregulated pumping will lead to upconing of saline water and therefore it is necessary to determine optimal rates and associated well locations (from an existing group of candidate wells that supply drinking water to the city of Delhi) that will minimize the total salinity. The nonlinear, non-convex problem is solved by embedding the calibrated groundwater model within a simulation-optimisation (S/O) framework. Optimisation is accomplished by using simulated annealing (SA), a search algorithm. The computational burden is primarily managed by replacing the numerical model with a surrogate simulator-artificial neural network (ANN). The model is applied to the real system to determine the optimal pumping schedule. The results of the operational model suggest that the skimming wells must be operated from optimal locations such that they are staggered in space and time to obtain the least saline water. 相似文献
60.
Forecasting of rainfall and subsequent river runoff is important for many operational problems and applications related to hydrology. Modeling river runoff often requires rigorous mathematical analysis of vast historical data to arrive at reasonable conclusions. In this paper we have applied the stochastic method to characterize and predict river runoffofthe perennial Kulfo River in southem Ethiopia. The time series analysis based auto regressive integrated moving average (ARIMA) approach is applied to mean monthly runoff data with 10 and 20 years spans. The varying length of the input runoff data is shown to influence the forecasting efficiency of the stochastic process. Preprocessing of the runoff time series data indicated that the data do not follow a seasonal pattern. Our forecasts were made using parsimonious non seasonal ARIMA models and the results were compared to actual 10-year and 20-year mean monthly runoff data of the Kulfo River. Our results indicate that river runoff forecasts based upon the 10-year data are more accurate and efficient than the model based on the 20-year time series. 相似文献