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DAVID HUDDART MATTHEW R. BENNETT NEIL F. GLASSER 《Boreas: An International Journal of Quaternary Research》1999,28(2):253-273
Although eskers are frequently described glaciofluvial landforms, they are poorly understood. To assist with the interpretation of Pleistocene examples, modern analogue data are required. This paper documents the morphology, sedimentology and formation of a 650 m long esker system in front of the high-arctic glacier Vegbreen in Svalbard. The esker is located between the Neoglacial maximum and the present ice front and appears to have formed both as a supraglacial trough-fill and as a channel/conduit-fill along the suture formed by two confluent glacier lobes. A range of sedimentary facies is preserved within this ridge system providing evidence for braided rivers, ephemeral lakes, episodic flow regimes and sediment gravity flows. This case study provides an important analogue for glaciofluvial sedimentation between retreating ice lobes. 相似文献
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DARREL A. SWIFT DAVID C. W. SANDERSON PETER W. NIENOW ROBERT G. BINGHAM IAN C. COCHRANE 《Boreas: An International Journal of Quaternary Research》2011,40(3):446-458
Swift, D. A., Sanderson, D. C. W., Nienow, P. W., Bingham, R. G. & Cochrane, I. C. 2010: Anomalous luminescence of subglacial sediment at Haut Glacier d'Arolla, Switzerland – a consequence of resetting at the glacier bed? Boreas, Vol. 40, pp. 446–458. 10.1111/j.1502‐3885.2010.00196.x. ISSN 0300‐9483. Luminescence has the potential to elucidate glacial geomorphic processes because primary glacial sediment sources and transport pathways are associated with contrasting degrees of exposure to light. Most notably, sediment entrained from extraglacial sources should be at least partially reset, whereas sediment produced by glacial erosion of subglacial bedrock should retain substantial luminescence commensurate with a geological irradiation history. We set out to test the validity of this assumption at Haut Glacier d'Arolla, Switzerland using sediment sampled extraglacially and from the glacier bed. Contrary to our expectations, the subglacial samples exhibited natural signals that were substantially lower than those of other sample groups, and further (albeit limited) analyses have indicated no obvious differences in sample‐group luminescence characteristics or behaviour that could account for this observation. For glaciological reasons, we can eliminate the possibilities that the subglacial sediment has been extraglacially reset or exposed in situ to heat or light. We therefore advocate investigation of possible resetting processes related to subglacial crushing and grinding, and speculate that such processes, if more generally present, may enable the dating of subglacially deposited tills using luminescence‐based techniques. 相似文献
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Regional dynamics in the globalising wine industry: the case of Marlborough, New Zealand 总被引:1,自引:0,他引:1
The rapid expansion of the New Zealand wine industry has rested largely on a specific wine commodity form, Marlborough Sauvignon Blanc. Global demand for a specialised product has provided the impetus for substantial development at the regional level, an increasingly complex industry structure, and for the intrusion of international capital. This paper explores the contests and relations within the industry through attention to the commodity's value-added chain, wherein recent developments are interpreted as a contest over the brand rents. The contemporary situation therefore may be explained through overlapping organisational and geographic framings of these relations: producer versus buyer-driven dynamics; regional–national and global interests; and inter- and intra-corporate strategies. The commercial contest for control of the region-varietal commodity reveals some paradoxical outcomes in which the region is reaffirmed as a site of investment in an evidently globalised industry, and the significance of who controls what fraction of the value chain is re-asserted. 相似文献
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DAVID PAGE 《Geology Today》1998,14(2):71-74
Sometimes between January and June 1996, the only known stegosaur tracks were stolen from Broome in north-western Australia (Fig. 1). Vandalism or loss of any type material is always to be lamented, yet there is good cause to suspect that the trackmaker at Broome was not a stegosaur. The reasons why this should be so relate to some of the factors involved in the formation of dinosaur trace fossils and the difficulties encountered in their interpretation. The stratigraphy at Broome is notable for preserving evidence of potential Wealden-type deposition in Australia. 相似文献
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DAVID A. ROTHERY 《Geology Today》1986,2(6):171-175
In January 1986 the spaceprobe Voyager-2 revealed details of the surfaces of the icy satellites of Uranus for the first time, including grabens, other faulted features, impact craters and possible ice flows. Despite their apparent similarity to some of the moons of Jupiter and Saturn, they highlight many new questions as to the evolution of, and interactions between, such bodies. 相似文献
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KEITH DAVID BENNETT 《Boreas: An International Journal of Quaternary Research》1986,15(3):209-215
Cores of organic postglacial sediment from Hall Lake, southern Ontario, Canada, are described. The laminated, calcareous sediments deposited between 9,000 and 8,000 B.P. have coherently slumped into the deep part of the lake, causing overturning and replication of parts of the sequence. This process may be considered as a mechanism for sediment focusing, since it involves reworking of marginal sediments into deeper areas. Unlike previously described mechanisms, it may be a source of error in the interpretation of diagrams of pollen percentages as well as accumulation rates. The slumping has only been recognized through the distortion of the laminae. It might not be possible to recognize slumping in unstratified sequences. 相似文献