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951.
Tracer tests represent the most appropriate approach for assessing hydrodispersive parameters such as transversal and longitudinal dispersivities or kinematic porosity on an aquifer scale. They are generally carried out by injecting a tracer in a borehole and measuring its concentration over time in neighboring boreholes by extracted volume sampling or downhole measurements. Logging is one of the most suitable methods for evaluating fissured reservoirs. But short circuits between fractures with different hydraulic potential through boreholes induce mixing phenomena that cannot be avoided without packers. This mixing can shift the breakthrough curves deduced from the logs for each producing fracture and distort determination of their location.
The method proposed in this paper aims at measuring the flow rate and the solute breakthrough for hydraulically active fractures, in open boreholes. It involves estimating a velocity profile along the borehole column by the analysis of two successive logs: a shift function according to depth is thus determined by comparison between log portions on each successive one. The velocity gradients reflect the inward or outward flow rates produced by each fracture. On the basis of these flow rates, it is possible to determine the mixing effects inside the borehole and then to plot unbiased breakthrough curves for each producing fracture.
This method was applied at a granitic site in the eastern Pyrenees. In spite of some questionable limitations, the results showed that the method seems adapted to situations with many fractures. The precise hydraulic pattern which is obtained at the borehole scale is discussed in terms of a dual porosity model. Furthermore, interpretation of the breakthrough curves for fractures corrected for mixing effects revealed that Peclet numbers are strongly underestimated if this phenomenon is not considered. 相似文献
The method proposed in this paper aims at measuring the flow rate and the solute breakthrough for hydraulically active fractures, in open boreholes. It involves estimating a velocity profile along the borehole column by the analysis of two successive logs: a shift function according to depth is thus determined by comparison between log portions on each successive one. The velocity gradients reflect the inward or outward flow rates produced by each fracture. On the basis of these flow rates, it is possible to determine the mixing effects inside the borehole and then to plot unbiased breakthrough curves for each producing fracture.
This method was applied at a granitic site in the eastern Pyrenees. In spite of some questionable limitations, the results showed that the method seems adapted to situations with many fractures. The precise hydraulic pattern which is obtained at the borehole scale is discussed in terms of a dual porosity model. Furthermore, interpretation of the breakthrough curves for fractures corrected for mixing effects revealed that Peclet numbers are strongly underestimated if this phenomenon is not considered. 相似文献
952.
An integration of sediment physical, chemical, biological, and toxicity data is necessary for a meaningful interpretation of the complex sediment conditions in the marine environment. Assessment of benthic community is a vital component for that interpretation, yet their evaluation is complex and requires a large expenditure of time and funds. Thus, there is a need for new tools that are less expensive and more understandable for managers. This paper presents a benthic biotope index to predict from physical and chemical variables the occurrence of macrobenthic habitats. Parameters such as sediment type, organic matter, depth, and hydrodynamic parameters were selected, through a discriminant analysis, to compute the index. Other authors have used multivariate methods to determine the benthic biotopes for Sado Estuary. The index proved to be a valid tool to classify and assess the spatial patterns of benthic habitat and to synthesize stress biotope gradients. 相似文献
953.
Multifractal Simulation of GeochemicalMap Patterns 总被引:3,自引:0,他引:3
Agterberg Frederik P Geological Survey of Canada Booth Street Ottawa KA E Canada 《中国地质大学学报(英文版)》2001,12(1)
INTRODUCTIONThe mathematical modeling of geochemical data continuesto present an important challenge to earth scientists. Basically,the available data are 2-dimensional realizations of 3dimensional patterns, which are the results of one or more genetic processes that usually are poorly understood. It may bedifficult to project from the observations into the rock mass. Inthis paper, multifractal modeling is advocated as a methodologyto characterize geochemical patterns. If a geochemical pa… 相似文献
954.
Jeremy P. Richards 《《地质学报》英文版》2014,88(Z2):535-537
Please refer to the attachment(s) for more details 相似文献
955.
D.J.Zhou J.L.Han B.Zhang K.J.Lee W.W.Zhu D.Li W.C.Jing W.-Y.Wang Y.K.Zhang J.C.Jiang J.R.Niu R.Luo H.Xu C.F.Zhang B.J.Wang J.W.Xu P.Wang Z.L.Yang Y.Feng 《天文和天体物理学研究(英文版)》2022,(12):57-72
We report the properties of more than 600 bursts(including cluster-bursts) detected from the repeating fast radio burst(FRB) source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio Telescope during an extremely active episode on UTC 2021 September 25–28, in a series of four papers. The observations were carried out in the band of 1.0–1.5 GHz by using the center beam of the L-band 19-beam receiver. We monitored the source in sixteen1 hr sessions and one 3 hr session spanning 23 ... 相似文献
956.
957.
The thick and widely exposed Jurassic and Triassic beds of Western Shansi and Northern Shensi are extraordinarily barren of animal fossils. With the exception of the ganoid fishes found by C. C. Wang, Licent and Teilhard in the special horizon (jasper-bearing limestone) which underlies the 相似文献
958.
大别造山带140~85Ma热窿伸展作用——年代学约束 总被引:21,自引:2,他引:21
区域热年代和差异冷却特性表明,140~85Ma大别造山带进入热窿伸展作用时期,由此引发基底广泛熔融、北淮阳剧烈火山喷溢以及合肥盆地断陷等过程.这次热窿事件包括强热伸展阶段(140~105Ma)和晚期衰退阶段(105~85Ma).在强热伸展阶段,热窿区集中在大别/红安地块,并以大别地块热窿作用最为强烈,某种意义上可将红安地块视为大别热窿翼部.大别热窿构造包括麻城-岳西热轴、穹核组合及其外围翼部,热轴平行造山带延向展布,北淮阳与高压/超高压(HP/UHP)岩石构成下滑翼部,岳西、罗田热窿核分别占据麻城-岳西热轴东、西两端,它们最终成型时代不一致、热窿伸展进程伴随着大别强热中心沿着麻城-岳西热轴迁移摆动,如果将热窿事件与造山带根部拆沉相联系,这种拆沉作用应以间歇性、迁移性、规模性与区域差异性为特征.在伸展衰退阶段(105~85Ma),大别造山带仍显现穹状热窿布局,但其伸展强度、岩浆活动显著减弱.解析热窿伸展作用,对于认识大别HP/UHP岩折返模型、“南北大别界限”以及造山过程机理具有重要启示意义. 相似文献
959.
Present study has continued the investigation on distribution of mercury in estuarine sediments of Patos Lagoon which began whilst assessing the after-effect of enormous accidental discharge of sulfuric acid into the estuary. An attempt to evaluate the contribution of anthropogenic effluents on mercury pollution in sediments was undertaken. The effluents from Rio Grande City sewages were categorized into four groups based on their sources. Comparison of mercury concentrations from those, indicated that domestic effluent was prevalent. Apparent geographic controls of effluent locations enriched in mercury on zones of polluted estuarine sediments were also revealed. Insufficient control on waste collecting and absence of sewage treatment are considered the principal causes of mercury pollution in estuarine sediments. 相似文献
960.
Andrew P. BUNGER Thierry MENAND Alexander CRUDEN ZHANG Xi Henry HALLS 《《地质学报》英文版》2016,90(Z1):141-142
正Like all swarming behavior in Nature,the selforganization expressed by the emergence of a natural spacing among a swarm’s members should be considered its most fundamental characteristic,and grasping the 相似文献