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81.
The paper presents the seasonal variation of 6300 Å line intensity at Calcutta with relative sunspot number, solar flare number and variable component of 10.7 cm solar flux. A study has been made and important results have been obtained which are as follows. (i) Intensity of 6300 Å line shows periodic variation with relative sunspot number, solar flare number and variable component of 10.7 cm solar flux during the period 1984–1986 which is the secondary peak of the descending phase of 21st solar cycle. (ii) 6300 Å line intensity at Cachoeira Paulista station, taken by Sahai et al. (1988), also shows periodic variation with solar parameters during the period 1978–1980 which is the peak phase of the solar cycle. (iii) A possible explanation of such a type of variation is also presented. 相似文献
82.
83.
Diamond crystallization has been studied in the SiO2–H2O–С, Mg2SiO4–H2O–С and H2O–С subsystems at 7.5 GPa and 1,600°C. We found that dissolution of initial graphite is followed by spontaneous nucleation
of diamond and growth of diamond on seed crystals. In 15-h runs, the degree of graphite to diamond transformation [α = MDm/(MDm + MGr)100, where MDm is mass of obtained diamond and MGr mass of residual graphite] reached 100% in H2O-rich fluids but was only 35–50% in water-saturated silicate melts. In 40-h runs, an abrupt decrease of α has been established
at the weight ratio H2O/(H2O + SiO2) ≤ 0.16 or H2O/(H2O + Mg2SiO4) ≤ 0.15. Our results indicate that α is a function of the concentration of water, which controls both the kinetics of diamond
nucleation and the intensity of carbon mass transfer in the systems. The most favorable conditions for diamond crystallization
in the mantle silicate environment at reliable PT-parameters occur in the fluid phase with low concentration of silicates
solute. In H2O-poor silicate melts diamond formation is questionable. 相似文献
84.
The pivotal point of the paper is to discuss the behavior of temperature, pressure, energy density as a function of volume along with determination of caloric EoS from following two model: w(z)=w 0+w 1ln(1+z) & . The time scale of instability for this two models is discussed. In the paper we then generalize our result and arrive at general expression for energy density irrespective of the model. The thermodynamical stability for both of the model and the general case is discussed from this viewpoint. We also arrive at a condition on the limiting behavior of thermodynamic parameter to validate the third law of thermodynamics and interpret the general mathematical expression of integration constant U 0 (what we get while integrating energy conservation equation) physically relating it to number of micro states. The constraint on the allowed values of the parameters of the models is discussed which ascertains stability of universe. The validity of thermodynamical laws within apparent and event horizon is discussed. 相似文献
85.
S. K. Deb Inderpreet Kaur C. M. Kishtawal P. K. Pal 《Theoretical and Applied Climatology》2014,115(3-4):693-702
The operational derivation of atmospheric motion vectors (AMVs) using infrared (10.5–12.5 μm) and water vapor (6.3–7.1 μm) channels of successive geostationary satellite images started in the 1980s. Subsequently, AMVs have become an important component for operational numerical weather prediction throughout the globe for the last decade or so. In India, at the Space Applications Centre, Indian Space Research Organisation, the operational derivation of AMVs (infrared winds and water vapor winds) from the Indian geostationary satellite Kalpana-1 has been initiated a few years back. Recently, an L-band radar lower atmosphere wind profiler (LAWP) has been installed at the National Atmospheric Research Laboratory, Gadanki located at (13.58°N, 79.28°E) for continuous high-resolution wind measurements in the lower atmosphere. In this study, a comparison of Kalpana-1 AMVs with wind measurements from LAWP and radiosonde has been carried out for a period of one and a half years. The performances of Kalpana-1 AMVs are also assessed by a separate comparison of Meteosat-7 AMVs, derived at the European Organisation for the Exploitation of Meteorological Satellites, with wind measurements from LAWP and radiosonde. Both sets of comparison show that AMVs from Kalpana-1 and Meteosat-7 are comparable over the Indian Ocean region. 相似文献
86.
Extreme temperatures are changing worldwide together with changes in the mean temperatures. This study investigates the long-term trends and variations of the monthly maximum and minimum temperatures and their effects on seasonal fluctuations in various climatological regions in India. The magnitude of the trends and their statistical significance were determined by parametric ordinary least square regression techniques and the variations were determined by the respective coefficient of variations. The results showed that the monthly maximum temperature increased, though unevenly, over the last century. Minimum temperature changes were more variable than maximum temperature changes, both temporally and spatially, with results of lesser significance. The results of this study are good indicators of Indian climate variability and its changes over the last century. 相似文献
87.
Gold and silver minerals from the Kupol epithermal deposit, Chukotka, were studied. A schematic sequence of mineral formation has been compiled. Specific mineral assemblages have been revealed in jarosite breccias: with native gold, uytenbogaardtite, fischesserite, acanthite, and native sulfur. We considered a possible mechanism of formation of gold and silver sulfides and selenides in volcanogenic deposits: They might have formed during solfatara and postsolfatara processes with the participation of volcanic gases or their condensates and sublimates as well as liquid sulfur (and selenium) and sulfuric hydrotherms produced under the interaction of volcanic gases with meteoric waters. The specific features of the Kupol deposit confirm the solfatara genesis of Au–Ag sulfides and selenides. 相似文献
88.
I. Sadhu Khan D. Lohar D. K. Pal 《Journal of the Indian Society of Remote Sensing》2003,31(4):261-269
Changes in land surface characteristics have become a matter of great concern in the recent years. It is particularly important
when the mesoscale phenomena control the climatic variables of a region. Gangetic West Bengal with its neighbourhood is such
a region where during premonsoon season, mesoscale phenomena, i.e., sea breeze circulation and severe convective development,
control the local climate of the season. It is also reported that a drastic changes in land use pattern has taken place in
recent period over the region, which might affect the local climate, resulting in severe water crisis over the semi-arid part
of the region. A detailed study has been undertaken to investigate the changes in land use pattern through satellite data
over the area and its possible impact on the local climate through numerical modeling. Satellite (IRS-IC and Landsat 4 and
5) data shows a sharp change in dynamic vegetation during this period, which is due to, increased agricultural practices in
the recent years. Mesoscale model indicates that agricultural practices hinder the development of sea breezes over the coastal
and inland places, causing less incursion of moisture towards inland. This may be associated with less number of convective
developments over the coastal and neighbouring places. 相似文献
89.
Natural Hazards - The Nirsa block, a coal mining area, and an industrial town lies in the southern part of Dhanbad district, at the border between the Indian states of Jharkhand and West Bengal.... 相似文献
90.
S. K. Deb Steve Wanzong C. S. Velden Inderpreet Kaur C. M. Kishtawal P. K. Pal W. P. Menzel 《Journal of the Indian Society of Remote Sensing》2014,42(4):679-687
The real-time operational use of atmospheric motion vectors (AMVs) at numerical weather prediction (NWP) centers in India are being adversely affected due to inaccurate height assignment of cloud tracers, especially in thin semi-transparent clouds. In India, the operational derivation of AMVs from the Indian geostationary satellite Kalpana-1 began few years ago. A statistical empirical method (SEM) of height assignment, based on a genetic algorithm, is currently used to estimate the height of the retrieved vectors from Kalpana-1. This method has many limitations. In this paper, attempts have been made to implement the widely used and well tested height assignment methods such as the infrared window (WIN) technique, the H2O intercept, and the cloud base method in the Kalpana-1 AMV retrieval algorithm. The new height assignment algorithm significantly improves the statistics of the retrieved winds when compared to radiosondes, especially in high and mid levels winds. 相似文献