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101.
Eugene E. Epstein Bryan H. Andrew Frank H. Briggs Bruce M. Jakosky Frank D. Palluconi 《Icarus》1983,56(3):465-475
Measurements at 3.5 mm of the disk-average brightness temperature of Mars during the 1978 opposition can be represented by (The errors cited are from the internal scatter; the estimated absolute calibration uncertainty is 3%.) This longitudinal variation must be taken into account if Mars is to be used as a calibration source at millimeter wavelengths. The total range of the 3.5-mm variation is three to four times larger than both the 2.8-cm and 20-μm variations. This unexpected result can possibly be explained by subsurface scattering from rocks ?1.5-cm radius. 相似文献
102.
103.
Firsova Alena D. Chebykin Eugene P. Kopyrina Liubov I. Rodionova Elena V. Chensky Dmitry A. Gubin Nikita A. Panov Vsevolod S. Pogodaeva Tatyana V. Bukin Yurij S. Suturin Alexandr N. Likhoshway Yelena V. 《Journal of Paleolimnology》2021,66(4):407-437
Journal of Paleolimnology - In this study, radiocarbon-dated geochemical and diatom records from Lake Vorota located within the informal meteorological ‘pole of cold’ of the northern... 相似文献
104.
Anna Tatarnikova Marina Burlak Eugene Kolotilov Natalia Metlova Victor Shenavrin Sergei Shugarov Taisija Tarasova Andrey Tatarnikov 《天文和天体物理学研究(英文版)》2018,(8)
A new set of low-resolution spectral and UBVJHKL-photometric observations of the symbiotic nova PU Vul is presented. The binary has been evolving after its symbiotic nova outburst in 1977 and now it is in the nebular stage. It is found that the third orbital cycle(after 1977) was characterized by great changes in associated light curves. Now, PU Vul exhibits a sine-wave shape in all the light curves(with an amplitude in the U band of about 0.7 mag), which is typical for symbiotic stars in the quiescent state. Brightness variability due to pulsations of the cool component is now clearly visible in the VRI light curves. The amplitude of the pulsations increases from 0.5 mag in the V band to 0.8 mag in the I band. These two types of variability, as well as a very slow change in the physical parameters of the hot component due to evolution after the outburst of 1977, influence the spectral energy distribution(SED)of the system. The variability of emission lines is highly complex. Only hydrogen line fluxes vary with orbital phase. An important feature of the third orbital cycle is the first emergence of the OVI, 6828 Raman scattering line. We determine the temperature of the hot component by means of the Zanstra method applied to the He II, 4686 line. Our estimate is about 150 000 K for the spectrum obtained near orbital maximum in 2014. The VO spectral index derived near pulsation minimum corresponds to M6 spectral class for the cool component of PU Vul. 相似文献
105.
Leung Juliana Y. Li Liangping Morgan Eugene Emami-Meybodi Hamid 《Mathematical Geosciences》2020,52(8):975-976
Mathematical Geosciences - 相似文献
106.
We report on observations of the full Moon brightness temperature covering the frequency range of 300-950 GHz, and also on observations of the lunar eclipse of July 16, 2000, though only covering the frequency range of 165-365 GHz due to poor atmospheric transmission at higher frequencies. All observations were performed from the summit of Mauna Kea (HI) using a Fourier Transform Spectrometer mounted on the Caltech Submillimeter Observatory and supplemented by measurements of the atmospheric opacity using a 183 GHz Water Vapor Monitor. The telescope was pointed to the center of the lunar disk (with a footprint of ∼45-15 km on the Moon at 300 through 900 GHz). In order to obtain the correct values of the Moon brightness temperatures at all frequencies we carefully corrected for the atmospheric absorption, which varies across the submillimeter domain. This correction is fully described. The measured pre-eclipse brightness temperature is around 337 K in the 165-365 GHz range. This temperature slightly increases with frequency to reach ∼353 K at 950 GHz, according to previous broader band data. The magnitude of the temperature drop observed during the eclipse at 265 GHz (central frequency of the band covered) was about ∼70 K, in very good agreement with previous millimeter-wave measurements of other lunar eclipses. We detected, in addition, a clear frequency trend in the temperature drop that has been compared to a thermal and microwave emission model of the lunar regolith, with the result of a good match of the relative flux drop at different frequencies between model and measurements. 相似文献
107.
108.
The Mann et al. (1998) Northern Hemisphere annual temperature reconstruction over 1400–1980 is examined in light of recent
criticisms concerning the nature and processing of included climate proxy data. A systematic sequence of analyses is presented
that examine issues concerning the proxy evidence, utilizing both indirect analyses via exclusion of proxies and processing
steps subject to criticism, and direct analyses of principal component (PC) processing methods in question. Altogether new
reconstructions over 1400–1980 are developed in both the indirect and direct analyses, which demonstrate that the Mann et
al. reconstruction is robust against the proxy-based criticisms addressed. In particular, reconstructed hemispheric temperatures
are demonstrated to be largely unaffected by the use or non-use of PCs to summarize proxy evidence from the data-rich North
American region. When proxy PCs are employed, neither the time period used to “center” the data before PC calculation nor
the way the PC calculations are performed significantly affects the results, as long as the full extent of the climate information
actually in the proxy data is represented by the PC time series. Clear convergence of the resulting climate reconstructions
is a strong indicator for achieving this criterion. Also, recent “corrections” to the Mann et al. reconstruction that suggest
15th century temperatures could have been as high as those of the late-20th century are shown to be without statistical and
climatological merit. Our examination does suggest that a slight modification to the original Mann et al. reconstruction is
justifiable for the first half of the 15th century (∼+0.05∘), which leaves entirely unaltered the primary conclusion of Mann et al. (as well as many other reconstructions) that both
the 20th century upward trend and high late-20th century hemispheric surface temperatures are anomalous over at least the
last 600 years. Our results are also used to evaluate the separate criticism of reduced amplitude in the Mann et al. reconstructions
over significant portions of 1400–1900, in relation to some other climate reconstructions and model-based examinations. We
find that, from the perspective of the proxy data themselves, such losses probably exist, but they may be smaller than those
reported in other recent work.
The National Center for Atmospheric Research is sponsored by the National Science Foundation, USA.
The authors contributed equally to the development of the research presented. 相似文献
109.
Ralph M. Gailis Alexander Hill Eugene Yee Trevor Hilderman 《Boundary-Layer Meteorology》2007,122(3):577-607
Fluctuating plume models provide a useful conceptual paradigm in the understanding of plume dispersion in a turbulent flow.
In particular, these models have enabled analytical predictions of higher-order concentration moments, and the form of the
one-point concentration probability density function (PDF). In this paper, we extend the traditional formalism of these models,
grounded in the theory of homogeneous and isotropic turbulent flow, to two cases: namely, a simple sheared boundary layer
and a large array of regular obstacles. Some very high-resolution measurements of plume dispersion in a water channel, obtained
using laser-induced fluorescence (LIF) line-scan techniques are utilised. These data enable us to extract time series of plume
centroid position (plume meander) and dispersion in the relative frame of reference in unprecedented detail. Consequently,
experimentally extracted PDFs are able to be directly compared with various theoretical forms proposed in the literature.
This includes the PDF of plume centroid motion, the PDF of concentration in the relative frame, and a variety of concentration
moments in the absolute and relative frames of reference. The analysis confirms the accuracy of some previously proposed functional
forms of model components used in fluctuating plume models, as well as suggesting some new forms necessary to deal with the
complex boundary conditions in the spatial domain. 相似文献
110.
A mineralogical and chemical analysis has been performed on the largest mass (8750 g) of the Girgenti, Italy, meteorite, from the collection of the Smithsonian Institution, Washington, D.C. The mineralogical composition is olivine, Fa24–25; hypersthene, Fs21 –22; plagioclase, An12; maskelynite; whitlockite; nickel-iron; troilite; chromite and ilmenite. Girgenti is a severly metamorphosed stone, whose total iron content (23.5%) is somewhat higher than the average for hypersthene chondrites. 相似文献