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31.
H. S. Sawant R. Ramesh J. R. Cecatto C. Faria F. C. R. Fernandes R. R. Rosa M. C. Andrade S. Stephany L. B. T. Cividanes C. A. I. Miranda L. C. L. Botti J. W. S. V. Boas J. H. Saito C. E. Moron N. D. Mascarenhas K. R. Subramanian M. S. Sundararajan E. Ebenezer M. R. Sankararaman 《Solar physics》2007,242(1-2):213-220
An East – West, one-dimensional radio interferometer array consisting of five parabolic dish antennas has been set up at Cachoeira
Paulista (longitude 45°0′20″ W, latitude 22°41′19″ S) for observations of the Sun and some of the strong sidereal sources
by the Instituto Nacional de Pesquisas Espaciais (INPE), Brazil. This is Phase-I of the proposed Brazilian Decimetric Array
and can be operated at any frequency in the range 1.2 – 1.7 GHz. The instrument has been in operation since November 2004
onwards at 1.6 GHz. The angular and temporal resolutions at this frequency are ∼3′ and 100 ms, respectively. Details of the
array, analog/digital receiver system, and a preliminary East – West one-dimensional solar image at the 1.6 GHz are presented
in this paper. 相似文献
32.
Soumya Roy Prasad Amrita Ghosh Koushik Panja Subhash Chandra Patra Sankar Narayan 《Geomagnetism and Aeronomy》2021,61(1):128-137
Geomagnetism and Aeronomy - The Mg II core-to-wing ratio (c/w ratio) data is used to derive the solar extreme UV emission which brings a vital role in the creation of the Earth’s ionosphere... 相似文献
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Sawant H.S. Subramanian K.R. Faria C. Fernandes F.C.R. Sobral J.H.A. Cecatto J.R. Rosa R.R. Vats H.O. Neri J.A.C.F. Alonso E.M.B. Mesquita F.P.V. Portezani V.A. Martinon A.R.F. 《Solar physics》2001,200(1-2):167-176
Digital, decimetric (200–2500 MHz) Brazilian Solar Spectroscope (BSS) with high time (10–1000 ms) and frequency (1–10 MHz) resolution is in regular operation since April, 1998, at National Space Research Institute (INPE) at São José dos Campos, Brazil. BSS operates in conjunction with a 9-m diameter polar mounted antenna. It allows to select suitable observing frequency range, frequency and time resolutions and data can be digitized up to 100 channels. BSS has capabilities of quasi-real time display of the ongoing dynamic spectra of the solar activity that enables the observer to modify observational parameters so as to suit a specific type of activity such as spikes and improve the quality of data acquisition and storage. Minimum detectable flux density of the spectroscope, for different combinations of the observational parameters, is 3 s.f.u. Observations are carried out routinely from 11 UT to 19 UT. Necessary software for data acquisition and reductions has been developed in IDL 5.3 environment. Data are available in FITS and ASCII formats. Absolute timing accuracy of the station is less than 3 ms. Here, we present examples of the bursts which have been recorded by BSS and available display facilities. 相似文献
35.
Short-Term Periodicities in the Time Series of Solar Radio Emissions at Different Solar Altitudes 总被引:1,自引:0,他引:1
A spectral analysis of the time series of daily values of 12 parameters, namely, ten solar radio emissions in the range 275–1755 MHz, 2800 MHz solar radio flux, and sunspot numbers for six continuous intervals of 132 values each during June 1997–July 1999 showed considerable differences from one interval to the next, indicating a nonstationary nature. A 27-day periodicity was noticed in Interval 2 (26.8 days), 3 (27.0 days), 5 (25.5 days), 6 (27.0 days). Other periodicities were near 11.4, 12.3, 13.3, 14.5, 15.5, 16.5, 35, 40, 50–70 days. Periodicities were very similar in a large vertical span of the coronal region corresponding to 670–1755 MHz. Above this region, the homogeneity disappeared. Below this region, there were complications and distortions due to localized solar surface phenomena. 相似文献
36.
Observations of a type II burst with fundamental and harmonic structure were made, with the Clark Lake Radio Observatory's E-W and N-S sweep frequency interferometers operating in the range 120–20 MHz with time and frequency resolution of 1 s and 100 kHz, respectively. The type II burst was preceded by a type III-type V, and the associated flare of importance SN was located at S 20 W 73. The interferometric data show that the fundamental and harmonic were coincident in position. Further, the type III positions as a function of frequency were practically the same as those of the type II burst. The implications of these results are discussed. 相似文献
37.
I. J. Singh S. K. Singh S. P. S. Kushwaha Subhash Ashutosh R. K. Singh 《Journal of the Indian Society of Remote Sensing》2004,32(2):167-174
The present study highlights the application of satellite remote sensing in the assessment and monitoring of the mangrove
forests along the coastline in Goa state of India. Based on onscreen visual interpretation techniques various land use and
land cover classes have been mapped and classified. An attempt has been made to analyse changes in the mangrove forest cover
from 1994 to 2001 using IRS-1B LISS-II and IRS-1D LISS-III data. An increase in the mangrove vegetation in the important estuaries
has been found during 1994 and 2001. During this period, the mangrove forest increased by 44.90 per cent as a result of increased
protection and consequent regeneration. Plantation of mangrove species has been raised in 876 ha (1985 to 1997) by the State
Forest Department¨ 相似文献
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Phytoplankton assemblages from tropical (Goa) and temperate (UK) locations were exposed to a 28 day dark period, followed by a period of re-exposure to light. During this time phytoplankton survival and changes in nutrient concentrations were mapped. The tropical plankton water samples showed high nutrient levels after the dark period which were utilised by cells during the re-exposure period. UK experiments looked at the effect of three different water types on population recovery after the 28 day dark period, and differences due to seasonal effects.The population growth observed during the re-exposure period in the tropical population was comparable to that of the temperate population. Water type affected recovery and of the three tested media fresh seawater promoted the highest levels of growth. Seasonality had a significant influence on species survival. Understanding the effects of all these factors can aid the development of effective risk assessments in ballast water management. 相似文献