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291.
Rob Inkpen 《Area》2007,39(1):31-42
Simple linear regression is used to interpret erosion rates on two shore platforms from the Kaikoura Peninsula, South Island, New Zealand. Using this analysis it is suggested that measured rates could be viewed as representatives of populations of erosion rates moving about a changing fitness landscape. The potential of such a view for understanding erosion rates is outlined. 相似文献
292.
Enhancing Geo-Service Chaining through Deep Service Descriptions 总被引:2,自引:0,他引:2
293.
Veerle Vandeginste Rudy Swennen Sarah A. Gleeson Rob M. Ellam Kirk Osadetz François Roure 《Mineralium Deposita》2007,42(8):913-935
Two Mississippi Valley-type (MVT) ore deposits, Kicking Horse and Monarch, have been studied with the aim of comparing the
ores at the two localities and to characterize the origin of the mineralizing fluids and the ore formation process(es). Both
deposits are hosted by the Middle Cambrian Cathedral Formation carbonate host rocks, Kicking Horse on the north and Monarch
on the south flank of the Kicking Horse valley near Field (SE British Columbia). The ore bodies are situated at the transition
of (western) basinal to (eastern) shallow-water strata of the paleo-Pacific passive margin succession in the Cordilleran Foreland
Province of the Western Canada Sedimentary Basin. Both deposits are related spatially to normal faults. In both localities,
the ore minerals are dominated by pyrite, sphalerite, and galena. Dolomite, minor quartz, and calcite are also present in
close association with the ores. The salinity (21–30 wt% NaCl eq.) and homogenization temperatures (63–182°C) measured in
fluid inclusions in carbonate, quartz, and sphalerite lie within the typical range of MVT fluid conditions. The good stoichiometry
(50–53 mol% CaCO3), low δ18O values (−21 to −14‰ Vienna Peedee belemnite) and relatively high homogenization temperatures (>95°C) of the dolomite suggest
the dolomites were formed under burial diagenesis. The ore-forming fluids probably interacted with siliciclastic units, based
on elevated Li contents and 87Sr/86Sr ratios, which are highest in the dolomite type after the main ore stage. We propose that the ores formed from the mixing
of a downward-infiltrating, sulfur-bearing halite-dissolution fluid with an upward-migrating, metal-rich evaporated seawater
fluid, which had already undergone minor mixing with a dilute fluid. 相似文献
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295.
Jim Ansell Willey Aspinall Geoffrey King Rob Westaway 《Geophysical Journal International》1986,84(1):201-206
Summary. Attention has recently been focused on the structure and composition of the lower crust in continental areas. It is generally believed that, except in special circumstances, ductile behaviour below mid-crustal depths precludes the brittle processes that cause earthquakes. The 1984 July 19 earthquake in North Wales occurred at the unexpected depth of 23 km. We report here the location of the larger aftershocks and the relocation of the main shock with respect to one of them. The lower crustal depths of the events are confirmed by tests with a wide range of models. The occurrence of earthquakes at these depths may be related to low heat flow in the region. 相似文献
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298.
From a nunatak in central North Greenland (81.5°N, 44.7°W) nine sites of Middle Proterozoic basic dykes, cutting Archaean basement, were palaeomagnetically investigated. After AF and thermal cleaning the nine dyke sites and three adjacently baked gneiss sites give a stable characteristic remanent mean direction of D = 265°, I = 21.5° ( N = 12, α 95 = 5.6°), the direction being confirmed by a detailed and positive baked contact test.
The polarity of the dykes in the nunatak area is opposite to that of the Zig-Zag Dal Basalts and the Midsommersø Dolerites in eastern North Greenland some 200–300 km away, the volcanics of which are assumed to be of similar age (about 1.25 Ga). The remanent directions of the two sets of data are antiparallel within the 95 per cent significance level of confidence.
When rotating Greenland 18° clockwise back to North America by the 'Bullard fit', the pole of the central North Greenland dolerites (NDL) falls at (14.3°N, 144.3°W). The reversed pole (14.3°S, 35.7°E) fits well on to the loop between 1.2 and 1.4 Ma on the apparent polar wander swath of Berger & York for cratonic North America.
The palaeomagnetic results from the Middle Proterozoic basic dykes from central North Greenland thus strengthen previous palaeomagnetic results from the Midsommersø Dolerites and Zig-Zag Dal Basalts from the Peary Land Region in eastern North Greenland, suggesting that Greenland was part of the North American craton at least for the period between c . 1.3 and 1 Ma (and probably up to the end of Cretaceous time). The major geographical meridian of Greenland was orientated approximately E–W, and the palaeo-latitude of Greenland was about 10°–15°. 相似文献
The polarity of the dykes in the nunatak area is opposite to that of the Zig-Zag Dal Basalts and the Midsommersø Dolerites in eastern North Greenland some 200–300 km away, the volcanics of which are assumed to be of similar age (about 1.25 Ga). The remanent directions of the two sets of data are antiparallel within the 95 per cent significance level of confidence.
When rotating Greenland 18° clockwise back to North America by the 'Bullard fit', the pole of the central North Greenland dolerites (NDL) falls at (14.3°N, 144.3°W). The reversed pole (14.3°S, 35.7°E) fits well on to the loop between 1.2 and 1.4 Ma on the apparent polar wander swath of Berger & York for cratonic North America.
The palaeomagnetic results from the Middle Proterozoic basic dykes from central North Greenland thus strengthen previous palaeomagnetic results from the Midsommersø Dolerites and Zig-Zag Dal Basalts from the Peary Land Region in eastern North Greenland, suggesting that Greenland was part of the North American craton at least for the period between c . 1.3 and 1 Ma (and probably up to the end of Cretaceous time). The major geographical meridian of Greenland was orientated approximately E–W, and the palaeo-latitude of Greenland was about 10°–15°. 相似文献
299.
300.
If human‐environment geography is central to the discipline, then human‐environment courses should be a sizable segment of the undergraduate curriculum. Undergraduate educational offerings are inadequate, however, meaning that geography departments are shortchanging their majors, missing opportunities to attract and inform the general student body, and failing to meet the needs of future K–12 educators. Unless geography provides satisfactory human‐environment education, it will likely have much less impact on twenty‐first‐century environmental science. 相似文献