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121.
We report a search for the acetylene (C2H2) nu 3 infrared vibration-rotation absorption near 3 micrometers toward the Becklin-Neugebauer source in the Orion molecular cloud. The relative abundance of C2H2/CO in the quiescent gas (9 km s-1 component) is less than 3 x 10(-3) (5 sigma). 相似文献
122.
H. M. Irvine 《地震工程与结构动力学》1980,8(3):267-273
A simple formula, equation (15), is derived for the peak additional cable tension that can be expected in a suspension bridge undergoing earthquake excitation. The method involves application of the response spectrum technique and rests on several plausible assumptions. The formula gives a reasonable upper bound, suitable for preliminary design estimates, irrespective of whether the ground motions at each end are in-phase or, as is probable with a long span bridge, whether they are out-of-phase. 相似文献
123.
William M. Irvine 《Icarus》1974,21(2):202-207
124.
A. M. Curry P. R. Porter T. D. L. Irvine‐Fynn G. Rees T. B. Sands J. Puttick 《地球表面变化过程与地形》2009,34(1):48-62
Particle size analysis and scanning electron microscopy have been used with some success to differentiate sediments sampled from varying geomorphological environments. In the paraglacial environment, however, discrimination of paraglacially reworked deposits from in situ glacigenic deposits has proven to be problematic. We consider till sediments that have been reworked by paraglacial debris flows and in situ, unreworked parent material, and apply a series of quantitative techniques in an attempt to discriminate samples from each environment. Initial analysis of particle size suggests some eluviation of fines from the debris‐flow‐reworked deposits but is of insufficient significance to allow reliable differentiation of geomorphological environment. Similarly, although slight differences are identified in terms of quartz grain surface microtextures and quartz grain outline shape, subsequent PCA, cluster and Fourier analyses fail to reliably differentiate quartz grains from each geomorphological environment, owing to high levels of intra‐sample heterogeneity. This lack of apparent difference may arise from a lack of paraglacial process operation of significant magnitude or duration for a characteristic process imprint to emerge at this scale of observation. Accordingly, further assessment of particle‐size and microtextural characteristics of glacial and paraglacial sediments may be most fruitful where sediments have been reworked over long distances. Moreover, differentiating glacial from paraglacial deposits is likely to yield the most reliable results where rigorous statistical analyses are combined with a wide range of sedimentological and geomorphological techniques. Copyright © 2008 John Wiley and Sons, Ltd. 相似文献
125.
Yueqing Xie Peter G. Cook Philip Brunner Dylan J. Irvine Craig T. Simmons 《Ground water》2014,52(5):769-774
Decline in regional water tables (RWT) can cause losing streams to disconnect from underlying aquifers. When this occurs, an inverted water table (IWT) will develop beneath the stream, and an unsaturated zone will be present between the IWT and the RWT. The IWT marks the base of the saturated zone beneath the stream. Although a few prior studies have suggested the likelihood of an IWT without a clogging layer, most of them have assumed that a low‐permeability streambed is required to reduce infiltration from surface water to groundwater, and that the IWT only occurs at the bottom of the low‐permeability layer. In this study, we use numerical simulations to show that the development of an IWT beneath an unclogged stream is theoretically possible under steady‐state conditions. For a stream width of 1 m above a homogeneous and isotropic sand aquifer with a 47 m deep RWT (measured in an observation point 20 m away from the center of the stream), an IWT will occur provided that the stream depth is less than a critical value of 4.1 m. This critical stream depth is the maximum water depth in the stream to maintain the occurrence of an IWT. The critical stream depth decreases with stream width. For a stream width of 6 m, the critical stream depth is only 1 mm. Thus while theoretically possible, an IWT is unlikely to occur at steady state without a clogging layer, unless a stream is very narrow or shallow and the RWT is very deep. 相似文献
126.
Increasing sediment loads entering the Lake Tanganyika ecosystem are hastening the need for improved understanding of the linkages between catchment characteristics and influent sediment transport and loading. Sediment loads of two catchments at the southern end of the lake were estimated for October 1998–December 1999, and catchment characteristics determined using GIS. It was found that both sediment yields and loads were higher from the catchment of the Lunzua River (19.8 t km?2 and 20,114 t, respectively) compared with that of the Kalambo (4.1 t km?2 and 12,197 t) in 1999. These differences were both attributed to the smaller size and higher road density of the Lunzua catchment, and suggest that previous recommendations regarding the positioning of underwater lake reserves fail to take into account the low sediment retention capacity of small mountainous rivers. Differences between the study rivers in the transport of suspended sediments, organic matter, and bedload sediments into the lake were also found, the latter determined by the novel application of the 'McLaren Model'. 相似文献
127.
We have sought interstellar ethyl-cyanide via its 202–101 transition towards two cold, dark clouds and report upper limits of the total column densities of 3×1012cm–2 and 2×1012cm–2 for TMC-1 and L134N, respectively. We also observed the 202–101 transition of vinyl cyanide previously identified in TMC-1 by Matthews and Sears (1983b). The detection of vinyl cyanide and the non-detection of ethyl cyanide in TMC-1 are consistent with gas phase ion-molecule chemical models, and there is thus no necessity of invoking grain surface synthesis for vinyl cyanide in cold clouds. 相似文献
128.
129.
P. G. Mestayer P. Durand P. Augustin S. Bastin J. -M. Bonnefond B. Bénech B. Campistron A. Coppalle H. Delbarre B. Dousset P. Drobinski A. Druilhet E. Fréjafon C. S. B. Grimmond D. Groleau M. Irvine C. Kergomard S. Kermadi J. -P. Lagouarde A. Lemonsu F. Lohou N. Long V. Masson C. Moppert J. Noilhan B. Offerle T. R. Oke G. Pigeon V. Puygrenier S. Roberts J. -M. Rosant F. Sanïd J. Salmond M. Talbaut J. Voogt 《Boundary-Layer Meteorology》2005,114(2):315-365
The UBL/CLU (urban boundary layer/couche limite urbaine) observation and modelling campaign is a side-project of the regional photochemistry campaign ESCOMPTE. UBL/CLU focuses on the dynamics and thermodynamics of the urban boundary layer of Marseille, on the Mediterranean coast of France. The objective of UBL/CLU is to document the four-dimensional structure of the urban boundary layer and its relation to the heat and moisture exchanges between the urban canopy and the atmosphere during periods of low wind conditions, from June 4 to July 16, 2001. The project took advantage of the comprehensive observational set-up of the ESCOMPTE campaign over the Berre–Marseille area, especially the ground-based remote sensing, airborne measurements, and the intensive documentation of the regional meteorology. Additional instrumentation was installed as part of UBL/CLU. Analysis objectives focus on (i) validation of several energy balance computational schemes such as LUMPS, TEB and SM2-U, (ii) ground truth and urban canopy signatures suitable for the estimation of urban albedos and aerodynamic surface temperatures from satellite data, (iii) high resolution mapping of urban land cover, land-use and aerodynamic parameters used in UBL models, and (iv) testing the ability of high resolution atmospheric models to simulate the structure of the UBL during land and sea breezes, and the related transport and diffusion of pollutants over different districts of the city. This paper presents initial results from such analyses and details of the overall experimental set-up. 相似文献
130.
Single-component (e.g., single-element) partition coefficients for silicate melts and the minerals that crystallize from them typically show large variations with temperature and melt composition. It is shown that, in particular cases, these variations can be calculated from two-component distribution coefficients that are practically constants, given the structural formula of the mineral and the melt composition. 相似文献