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71.
72.
R. H. Kripalani A. Kulkarni S. R. Inamdar K. D. Prasad 《Meteorology and Atmospheric Physics》1999,69(3-4):195-203
Summary In this study a search for teleconnection is made between the Northern Hemisphere lower stratospheric geopotential heights and Indian Monsoon Rainfall (IMR) through the correlation analysis approach. Monthly grid-point 50 hPa geopotential height data and the June to September IMR are used for the period 1958–1990.Analysis reveal that there are domains over the Northern Hemisphere where the variation of the geopotential heights during the preceding months of the monsoon period are related with the interannual behaviour of the IMR. During January and February significant positive correlations are seen along the lower latitudes (10°–20° N). However, the maximum relationship is seen during March, with high positive correlations over the Canadian sector and negative correlations over the east Asian sector. The correlation configuration weakens considerably, once the ENSO (El Niño Southern Oscillation) cases are excluded, suggesting that the correlation pattern obtained may be a manifestation of the ENSO cycle. Implications of these results in the long range forecasting of IMR are also discussed.With 5 Figures 相似文献
73.
This study presents the monthly climatology and variability of the historical soviet snow depth data. This data set was developed
under the bilateral data exchange agreement between United States of America and the former Union of Soviet Socialist Republics.
The original data is for 284 stations for periods varying from 1881 upto 1985. The seasonal cycle of the mean snow depth has
been presented both as spatial maps and as averages over key locations. The deepest snow (=80 cms/day) areas are found over
Siberia (in Particular over 80′–100 ′E, 55′–70 ′N) during March. Over the course of the annual cycle average snow depth over
this region changes dramatically from about 10 cms in October to about 80 cms in March. The variability is presented in the
form of spatial maps of standard deviation. To investigate the interaction of snow depth with Indian monsoon rainfall (IMR),
lag and lead correlation coefficients are computed. Results reveal that the winter-time snow depth over western Eurasia surrounding
Moscow (eastern Eurasia in central Siberia) shows significant negative (positive) relationship with subsequent IMR. Following
the monsoon the signs of relationship reverse over both the regions. This correlation structure is indicative of a midlatitude
longwave pattern with an anomalous ridge (trough) over Asia during the winter prior to a strong (weak) monsoon. As the time
progresses from winter to spring, the coherent areas of significant relationship show southeastward propagation. Empirical
orthogonal function analysis of the snow depth reveal that the first mode describes a dipole-type structure with one centre
around Moscow and the other over central Siberia, depicting similar pattern as the spatial correlation structure. The decadal-scale
IMR variations seem to be more associated with the Northern Hemisphere midlatitude snow depth variations rather than with
the tropical ENSO (El Nino Southern Oscillation) variability.
Received: 16 March 1998 / Accepted: 24 December 1998 相似文献
74.
Measurements of intensities at two fixed wavelengths in the OH (7-2) band were carried out at Mt Abu (24.6° N, 76.7° E) from
1973–76 to estimate neutral temperature in the region of 80–90 km altitude. It was observed that on some nights the temperature
in this region shows periodic oscillations throughout the night. It was found from statistical analysis that the periods of
these fluctuations are comparable to the theoretically predicted periods of internal gravity waves.
If the periodic temperature variations observed in this region are attributed to the influence of gravity waves, according
to the Hines theory only the magnitude of the horizontal component of wave-induced wind velocity can be computed. Using the
measured relative temperature fluctuations it is found that the magnitude is 15–30 m/sec. 相似文献
75.
The growth rate of electromagnetic waves, in the whistler mode frequency range, in the presence of field aligned currents is calculated. A model for the occurrence of circular polarizations in pulses of pulsars is presented. 相似文献
76.
Poonam Chandra Govind Swarup Vasant K. Kulkarni Nimisha G. Kantharia 《Journal of Astrophysics and Astronomy》2004,25(1-2):57-65
We have made observations of the as sociated HI absorption of a high redshift radio galaxy 0902+34 atz = 3.395 with the Giant Meterwave Radio Telescope in the 323 ± 1 MHz band. We find a narrow absorption line with a flux density
of 11.5 mJy at a redshift of 3.397 consistent with that observed by Usonet al. (1991), Briggset al. (1993) and de Bruyn (1996). A weak broad absorption feature reported by de Bruyn (1996) has not been detected in our observations.
We also place an upper limit of 4mJy(2σ) on emission line strength at the position where Usonet al. (1991) claimed to have found a narrow emission line. 相似文献
77.
Non-linear wave-particle interaction in the whistler mode in a non-uniform magnetic field is considered. The effect of the second order resonant particles arising due to nonuniformity of the ambient magnetic field is found to be dominant near the equatorial plane of the Earth. The equations describing the time development of the amplitude and phase of the wave packet have been solved numerically by computing the resonant particle current in a self-consistent manner. The growth of the waves because of trapped particles is found to be substantial for triggering an emission and the changes in phase lead to the frequency-time structure. It is capable of reproducing all kinds of frequency time structure as observed in the case of a morse pulse. 相似文献
78.
Rahul Ramachandran Manil Maskey Ajinkya Kulkarni Helen Conover U. S. Nair Sunil Movva 《Earth Science Informatics》2012,5(1):33-41
“Open science,” where researchers share and publish every element of their research process in addition to the final results,
can foster novel ways of collaboration among researchers and has the potential to spontaneously create new virtual research
collaborations. Based on scientific interest, these new virtual research collaborations can cut across traditional boundaries
such as institutions and organizations. Advances in technology allow for software tools that can be used by different research
groups and institutions to build and support virtual collaborations and infuse open science. This paper describes Talkoot,
a software toolkit designed and developed by the authors to provide Earth Science researchers a ready-to-use knowledge management
environment and an online platform for collaboration. Talkoot allows Earth Science researchers a means to systematically gather,
tag and share their data, analysis workflows and research notes. These Talkoot features are designed to foster rapid knowledge
sharing within a virtual community. Talkoot can be utilized by small to medium sized groups and research centers, as well
as large enterprises such a national laboratories and federal agencies. 相似文献
79.
80.
The relationship between the velocity of CMEs and the plasma temperature of the associated X-ray solar flares is investigated.The velocity of CMEs increases with plasma temperature(R=0.82)and photon index below the break energy(R=0.60)of X-ray flares.The heating of the coronal plasma appears to be significant with respect to the kinetics of a CME from the reconnection region where the flare also occurs.We propose that the initiation and velocity of CMEs perhaps depend upon the dominant process of conversion of the magnetic field energy of the active region to heating/accelerating the coronal plasma in the reconnected loops.Results show that a flare and the associated CME are two components of one energy release system,perhaps,magnetic field free energy. 相似文献