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81.
ASSESSING THE DICE MODEL: UNCERTAINTY ASSOCIATED WITH THE EMISSION AND RETENTION OF GREENHOUSE GASES 总被引:2,自引:0,他引:2
ROBERT K. KAUFMANN 《Climatic change》1997,35(4):435-448
Analysis of the DICE model indicates that it contains unsupported assumptions, simple extrapolations, and misspecifications that cause it to understate the rate at which economic activity emits greenhouse gases and the rate at which the atmosphere retains greenhouse gases. The model assumes a world population that is 2 billion people lower than the base case' projected by demographers. The model extrapolates a decline in the quantity of greenhouse gases emitted per unit of economic activity that is possible only if there is a structural break in the economic and engineering factors that have determined this ratio over the last century. The model uses a single equation to simulate the rate at which greenhouse gases accumulate in the atmosphere. The forecast for the airborne fraction generated by this equation contradicts forecasts generated by models that represent the physical and chemical processes which determine the movement of carbon from the atmosphere to the ocean. When these unsupported assumptions, simple extrapolations, and misspecifications are remedied with simple fixes, the economic impact of global climate change increases several fold. Similarly, these remedies increase the impact of uncertainty on estimates for the economic impact of global climate change. Together, these results indicate that considerable scientific and economic research is needed before the threat of climate change can be dismissed with any degree of certainty. 相似文献
82.
The granodioritic Rader Creek pluton of the composite Boulderbatholith contains microperthitic alkali feldspar of bulk compositionOr65 to Or86 with a structurally variable potassic phase. Completecell parameters, 2V measurements, and bulk composition are givenfor 11 feldspar samples. The 131 and 131 reflections for theseand 58 additional samples show the following structural typesin the potassic phase: orthoclase only; orthoclase with subordinatemaximum or near-maximum microcline (obliquity = 0.751.00);orthoclase with subordinate intermediate microcline (obliquity= 0.640.71); and intermediate microcline (obliquity =0.560.77) with subordinate orthoclase. Within the plutondifferent feldspar structural types occur in zones whose boundariesare approximately parallel to contacts with younger intrusiverocks cutting the Rader Creek pluton but are, in places, nearlyperpendicular to zonation within the pluton defined by rockcomposition. In general, the orthoclase zone is closest to thecontact with younger intrusives; the intermediate microclinezone is the most distant. Bulk compositions of alkali feldsparare more potassic in the orthoclase zone than elsewhere. Thedata suggest a complex history for the alkali feldspar, involvingat least two stages: 1. Exsolution and partial inversion oforthoclase to intermediate microcline during cooling of theRader Creek pluton; 2. Transformation of the intermediate-microclineassemblage to orthoclase during reheating of the pluton at thetime of intrusion of younger plutons of the batholith. The transitionalstage in this transformation is characterized by orthoclaseco-existing with subordinate microcline, whose obliquity usuallyapproaches that of maximum microcline. 相似文献
83.
Abstract One of the most talked about issues with respect to development, transportation, and conversion of the energy resources of the Western United States is the water requirement and its consequent impacts upon the ambience of that part of the country. In conjunction with other studies conducted by the US Geological Survey of water use in the conversion and transportation of the West's coal, an analysis of water use and environmental implications of coal slurry pipeline transport is presented. Simulations of a hypothetical slurry pipeline of 1000 mile length transporting 12.5 million tons per year indicate that pipeline costs and energy requirements are quite sensitive to the coal-to-water ratio. For realistic water prices, the optimal ratio will not vary far from the 50/50 ratio by weight. In comparison to other methods of energy conversion and transport, coal slurry pipelines utilize about a third of the amount of water required for coal gasification, and about a fifth of the amount required for onsite electrical generation. An analysis of net energy output from operating alternative energy transportation systems for the assumed conditions indicates that both slurry pipeline and rail shipment require approximately 4.5 per cent of the potential electrical energy output of the coal transported and high-voltage, direct-current transportation requires approximately 6.5 per cent. The environmental impacts of the different transport options are so substantially different that a common basis for comparison does not exist. 相似文献
84.
ROBERT B. THOMAS 《水文科学杂志》2013,58(5):499-514
Abstract Rating curves are widely used for directly assessing changes in the suspended sediment delivery process and indirectly for estimating total yields. Four sampling methods were simulated over a 31-day record of suspended sediment from the North Fork of the Mad River near Korbel, California. The position and size of the four groups of plotted slope/intercept pairs indicated differences in bias and variance among the methods. Estimates of total yield for the 31-day period and for storms of three sizes were also biased according to sampling method. A standard bias-correcting technique improved yield estimates, but did not remove sampling bias uniformly. Methods of data collection have a large and systematic effect on the estimation of rating-curve parameters and on estimates of suspended sediment yield. Differences attributed to land management may, in fact, result from changes in sampling methods. 相似文献
85.
86.
ROBERT S. SOMMER JULIANE PASOLD ULRICH SCHM
LCKE 《Boreas: An International Journal of Quaternary Research》2008,37(3):458-464
At the end of the Pleistocene, environmental conditions in the Baltic Basin were affected by the melting glaciers and the resultant freshwater bodies. In contrast to various seal species, there is no subfossil evidence of the harbour porpoise (Phocoena phocoena) from the early Holocene stages of the Baltic Basin. This article is an attempt to clarify the colonization of the harbour porpoise into the Baltic Sea and to reveal the ecological background of this process. All published Holocene subfossil records from the porpoise in the Baltic region were sought and supplemented with those from museums and zoological collections; 148 records document the porpoise's occurrence. The earliest records of the harbour porpoise date from the time between 9600 and 7000 cal. yr BP and originate from the early and middle Mesolithic coastal settlements of the Maglemose and Kongemose culture during the early Littorina stage. Around 7500–5700 cal. yr BP, the porpoise is recorded frequently at many localities from late Mesolithic (Ertebølle culture) and Neolithic in the coastal areas of the western Baltic Sea, as well as for the first time in the Gulfs of Bothnia and Finland. Since 4000 cal. yr BP, P. phocoena has only been recorded in the western Baltic. We suggest that immigration and dispersion of P. phocoena into the Baltic Sea was connected with the Littorina transgression beginning around 9000 cal. yr BP. The continuous influx of seawater and the associated ecological changes led to a new, very species‐rich, fish community and adequate living conditions for the harbour porpoise. 相似文献
87.
88.
Abstract– The molecular structure of the insoluble organic matter (IOM) from Murchison meteorite has been investigated by our group for several years using a large set of analytical methods including various spectroscopies (Fourier transform infrared spectroscopy, nuclear magnetic resonance, electron paramagnetic resonance, X‐ray absorption near‐edge spectroscopy), high resolution electron microscopy, and thermal (pyrolyses in the presence or not of tetramethylammonium hydroxide) and chemical (RuO4 oxidation) degradations. Taken together, these techniques provided a wealth of qualitative and quantitative information, from which we derived 11 elemental and molecular parameters on the same IOM residue. In addition to the basic elemental composition, these parameters describe the distribution of the different types of carbon, nitrogen, and sulfur atoms as well as the size of the polyaromatic units. For this molecular structure, we therefore propose a model which fits with these 11 molecular quantitative parameters. Several cosmochemical implications are derived from this structure. Based on the fact that aromatic moieties are highly substituted and aliphatic chains highly branched, it can be anticipated that the synthesis of this IOM occurred through successive additions of single carbon units in the gas‐phase ending by a spontaneous cyclization for chain length ≥7 C. As a whole, these observations favor an organosynthesis in the solar T‐Tauri disk. 相似文献
89.
MARK D. BATEMAN PAUL C. BUCKLAND MARTIN A. WHYTE ROBERT A. ASHURST CLAIRE BOULTER EVA PANAGIOTAKOPULU 《Boreas: An International Journal of Quaternary Research》2011,40(4):573-584
Bateman, M. D., Buckland, P. C., Whyte, M. A., Ashurst, R. A., Boulter, C. & Panagiotakopulu, E. 2011: Re‐evaluation of the Last Glacial Maximum typesite at Dimlington, UK. Boreas, 10.1111/j.1502‐3885.2011.00204.x. ISSN 0300‐9483. Recent erosion has allowed re‐examination of the stratigraphy and sampling for both optically stimulated luminescence dating and palaeoecological analysis of the key sections in the Last Glacial Maximum deposits at Dimlington in East Yorkshire, England. Both stratigraphy and fossil insect evidence support a subaerial origin for laminated and cross‐bedded sediments between two diamictons previously interpreted as synchronous. The fossil biota indicates conditions similar to those of a pond on sandur in the high Arctic, with little or no vegetation cover. The existence of distinct oscillations of the ice front is indicated. The first, within the period 21.7–16.2 ka, appears coincident with climate warming, as deduced from Greenland ice‐core evidence, and is interpreted as an ice stream associated with changing flow patterns within the British–Irish Ice Sheet (BIIS). The second, dating between 16.2 and 15.5 ka, appears to coincide with a climatic cooling, although current models show that the BIIS had by this period already retreated back to ice centres. This new evidence supports the view that the eastern sector of the BIIS did not reach its maximal extent synchronously with other parts of the BIIS. 相似文献
90.