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121.
R.G.W. Ward 《Applied geography (Sevenoaks, England)》1984,4(2):109-133
The paper presents a method for predicting avalanche activity from meteorological data which is suitable for Scottish snow conditions. Two main types of avalanche are distinguished. Direct-action avalanches are the result of fresh snow accumulation and may release after approximately 200 mm of fresh snow has fallen over a period of a few days. They become extremely likely if a further 100 mm falls in a single day. Climax avalanches are the result of strength loss in the snow cover, due either to thawing or persistent cold. Thaws may produce an avalanche after only three or four days with maximum temperatures around 2°C. Alternatively, if maximum temperatures remain below ?4°C for over a week, and especially if cold weather persists for two weeks, slab avalanches of dry snow are likely to occur. Between these two types are several possible avalanche situations in which fresh snow accumulation is combined with high or low temperatures. Topography plays a passive role, and determines where avalanche activity is most likely. Free faces, smooth surfaces and slopes in the lee of major storms respond most rapidly to the onset of avalanche conditions. 相似文献
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T. P. Roberts M. R. Goad M. J. Ward R. S. Warwick 《Monthly notices of the Royal Astronomical Society》2003,342(3):709-714
We report the results of an observation of a large-diameter (110 pc) supernova remnant (SNR) found to encircle the position of the ultraluminous X-ray source (ULX) IC 342 X-1. The inferred initial energy input to the SNR is at least 2–3 times greater than the canonical energy for an 'ordinary' SNR. Two regions on the inside of the shell are bright in [O iii ]λ5007 emission, possibly as the result of X-ray photoionization by the ULX. If this is the case, then the morphology of this nebulosity implies that the X-ray emission from the ULX is anisotropic. The presence of the ULX, most probably a black hole X-ray binary, within an unusually energetic SNR suggests that we may be observing the aftermath of a gamma-ray burst, although other origins for the energetic nebula are discussed. 相似文献
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Savonoski Crater, a small basin about 1700 feet in diameter, is located on a ridge of gently-dipping Jurassic sandstone in Katmai National Monument, southwestern Alaska. Reconnaisance geological, geophysical, and petrographic studies suggest that it was formed either by volcanic processes or meteorite impact prior to the end of the latest glaciation in the region. Surface ejecta, if originally present, apparently have been removed by glaciation. No distinctive shock-metamorphic effects were observed in the few rock specimens collected. Final determination of the crater's origin will require more extensive field studies or drilling in the center of the crater. 相似文献
126.
P. Lira M. J. Ward A. Zezas S. S. Murray 《Monthly notices of the Royal Astronomical Society》2002,333(3):709-714
We present high spatial resolution X-ray Chandra HRC and HST WFPC2 H α observations of the prototypical infrared-luminous galaxy NGC 6240. The central region of this system shows a remarkably complex morphology, with filaments and loops observed in the optical and X-rays. The total X-ray luminosity is dominated by the extended emission. Both nuclei are clearly detected in the HRC image and both appear to be extended. The energetics of the nuclei imply that the southern nucleus is the more plausible counterpart to the obscured active galactic nucleus. The overall spectral energy distribution of the galaxy is in good agreement with a blend of starburst and AGN components that have similar bolometric luminosities, L bol ∼5×1045 erg s-1 , with the starburst dominating the observed continuum in the near-infrared ( K band), optical and soft X-ray bands. 相似文献
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128.
The role of megatides and relative sea level in controlling the deglaciation of the British–Irish and Fennoscandian ice sheets 下载免费PDF全文
Key external forcing factors have been proposed to explain the collapse of ice sheets, including atmospheric and ocean temperatures, subglacial topography, relative sea level and tidal amplitudes. For past ice sheets it has not hitherto been possible to separate relative sea level and tidal amplitudes from the other controls to analyse their influence on deglaciation style and rate. Here we isolate the relative sea level and tidal amplitude controls on key ice stream sectors of the last British–Irish and Fennoscandian ice sheets using published glacial isostatic adjustment models, combined with a new and previously published palaeotidal models for the NE Atlantic since the Last Glacial Maximum (22 ka BP). Relative sea level and tidal amplitude data are combined into a sea surface elevation index for each ice stream sector demonstrating that these controls were potentially important drivers of deglaciation in the western British Irish Ice Sheet ice stream sectors. In contrast, the Norwegian Channel Ice Stream was characterized by falling relative sea level and small tidal amplitudes during most of the deglaciation. As these simulations provide a basis for observational field testing we propose a means of identifying the significance of sea level and tidal amplitudes in ice sheet collapse. 相似文献
129.
Yus Budiyono Jeroen Aerts JanJaap Brinkman Muh Aris Marfai Philip Ward 《Natural Hazards》2015,75(1):389-413
130.
Haid Maren Gohm Alexander Umek Lukas Ward Helen C. Rotach Mathias W. 《Boundary-Layer Meteorology》2022,182(3):335-362
Boundary-Layer Meteorology - We present a comprehensive analysis of four south föhn events observed during the Penetration and Interruption of Alpine Foehn (PIANO) field campaign in the Inn... 相似文献