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651.
Quaternary coastal lithofacies,sequence development and stratigraphy in a passive margin setting,North Carolina and Virginia,USA 总被引:3,自引:0,他引:3
PETER R. PARHAM STANLEY R. RIGGS STEPHEN J. CULVER DAVID J. MALLINSON W. JACK RINK KEVIN BURDETTE 《Sedimentology》2013,60(2):503-547
Lithofacies analysis is fundamental to unravelling the succession of depositional environments associated with sea‐level fluctuations. These successions and their timing are often poorly understood. This report defines lithofacies encountered within the north‐eastern North Carolina and south‐eastern Virginia Quaternary section, interprets their depositional environments, presents a model for coastal depositional sequence development in a passive margin setting and uses this understanding to develop the stratigraphy and Quaternary evolutionary history of the region. Data were obtained from numerous drill cores and outcrops. Chronology was based on age estimates acquired using optically stimulated luminescence, amino acid racemization, Uranium series and radiocarbon dating techniques. Geomorphic patterns were identified and interpreted using light detection and ranging imagery. Since lithofacies occurrence, distribution and stratigraphic patterns are different on interfluves than in palaeo‐valleys, this study focused on interfluves to obtain a record of highstand sea‐level cycles with minimal alteration by fluvial processes during subsequent lowstands. Nine primary lithofacies and four diagenetic facies were identified in outcrops and cores. The uppermost depositional sequence on interfluves exhibits an upward succession from shelly marine lithofacies to tidal estuarine lithofacies and is bounded below by a marine ravinement surface and above by the modern land surface. Older depositional sequences in the subsurface are typically bounded above and below by marine ravinement surfaces. Portions of seven depositional sequences were recognized and interpreted to represent deposition from late middle Pleistocene to present. Erosional processes associated with each successive depositional sequence removed portions of older depositional sequences. The stratigraphic record of the most recent sea‐level highstands (Marine Isotope Stage 5a and Marine Isotope Stage 3) is best preserved. Glacio‐isostatic adjustment has influenced depositional patterns so that deposits associated with late Quaternary sea‐level highstands (Marine Isotope Stages 5c, 5a and 3), which did not reach as high as present sea‐level according to equatorial eustatic records, are uplifted and emergent within the study area. 相似文献
652.
The continuity of clay-rich fault gouge has a large effect on fluid transmissibility of faults in sand–clay sequences, but clay gouge continuity and composition in 3D are not well known. We report observations of 3D clay smear continuity in water-saturated sandbox experiments where the sheared clay layers were excavated after deformation. The experiments build on existing work on the evolution of clay gouge in similar 2D experiments where interpretations were made in profile view.We used well-known model materials (“Benchmark” sand and uncemented kaolinite–sand mixtures) that were further characterized using standardized geotechnical tests and triaxial compression experiments at effective pressures corresponding to the sandbox experiments. Results show a nonlinear failure envelope of the sand, in agreement with existing models. Unconfined compression experiments with the clay show cohesion around 50 Pa and brittle behavior.A sheared, ductile clay layer embedded in sand above a 70° dipping basement fault reveals a complex, natural-looking clay gouge architecture with relay ramps, breached relays and fault lenses. The clay gouge shows clear variations in composition and thickness and becomes locally discontinuous at throw-thickness ratios above 7, in contrast to our earlier 2D observations where discontinuous clay-gouge only formed in cemented clay layers. In addition to tectonic telescoping in the relays, the thin, continuous parts of the clay gouge were transformed from an initial pure clay by mechanical mixing of sand and clay.We also discuss the applicability of these results to the evolution of normal fault zones and deformation bands in sand–clay sequences at effective pressures below the onset of cataclasis and conclude that in fault zones a higher degree of internal segmentation reduces the probability of the formation of discontinuities. 相似文献
653.
654.
Global marine policy-making and related institutional architectures have been within the domain of the United Nations system in general and its specialized agencies (FAO, IMO, UNESCO/IOC, UNEP) in particular. At the regional and country levels there are a large number of organizations and agencies that are involved in various marine issues in the programme areas of Regional Indigenous Organizations (ASEAN, CARICOM, SPF., organizations belonging to these regions). The paper reveals that the United Nations system represents a top-down policy making and institutional approach, whereas a combination of nation-state and their regional indigenous organizations represents a bottom-up approach. The paper outlines some inefficiencies of the United Nations system and provides an option for improving the effectiveness of regional indigenous organizations. 相似文献
655.
GARY J. HAMPSON M. ROYHAN GANI HIRANYA SAHOO ANDREAS RITTERSBACHER ANDREW RANSON JOHN A. HOWELL SIMON J. BUCKLEY BRYAN BRACKEN 《Sedimentology》2012,59(7):2226-2258
Current models of alluvial to coastal plain stratigraphy are concept‐driven and focus on relative sea‐level as an allogenic control. These models are tested herein using data from a large (ca 100 km long and 300 m thick), continuous outcrop belt (Upper Cretaceous Blackhawk Formation, central Utah, USA). Many channelized fluvial sandbodies in the Blackhawk Formation have a multilateral and multistorey internal character, and they generally increase in size and abundance (from ca 10% to ca 30% of the strata) from base to top of the formation. These regional, low‐resolution trends exhibit much local variation, but are interpreted to reflect progressively decreasing tectonic subsidence in the upper Blackhawk Formation and overlying Castlegate Sandstone. The trend may also incorporate progressively more frequent channel avulsion during deposition of the lower Blackhawk Formation. Laterally extensive coal zones formed on the coastal plain during shallow‐marine transgressions, and define the high‐resolution stratigraphic framework of the lower Blackhawk Formation. Large (up to 25 m thick and 1 to 6 km wide), multistorey, multilateral, fluvial channel‐complex sandbodies that overlie composite erosion surfaces occur at distinct stratigraphic levels, and are interpreted as fluvial incised valley fills. Low amplitude (<30 m) relative sea‐level variations are interpreted as the dominant control on stratigraphic architecture in the lower Blackhawk Formation, which was deposited up to 50 km inland from the coeval shoreline. In contrast, the high‐resolution stratigraphy of the upper Blackhawk Formation is poorly defined, and channelized fluvial sandbodies are poorly organized. Vertical and laterally offset stacking of a small proportion (<10%) of sandbodies produced ‘clusters’ that are not confined by ‘master’ erosion surfaces. Avulsion is interpreted to dominate the stratigraphic architecture of the upper Blackhawk Formation. This data‐driven analysis indicates that alluvial to coastal plain stratigraphic architecture reflects a combination of various allogenic controls and autogenic behaviours. The relative sea‐level control emphasized in sequence stratigraphic models is only rarely dominant. 相似文献
656.
657.
地下储层构型表征是近十几年发展起来的油气藏开发地质研究方向。与露头构型分析不同的是,地下储层构型表征主要依据地震信息和多井信息,相应地发展了两类方法,其一为地震沉积学(地貌学)方法,即通过三维地震资料地层切片等方式,利用地震成像特征研究沉积单元的分布;其二为多井模式预测方法,即通过将不同级次的定量构型模式与地下井资料(包括动态监测资料)进行拟合,分级约束并预测不同级次的构型单元的井间分布。论述了这两类方法的起源、基本原理、应用范畴及存在问题,并根据油田生产要求与技术发展提出了进一步深入研究的方向,包括三维定量构型模式的深化研究、储层构型地震响应及解释方法研究、多井模拟拟合方法的改进与创新等。 相似文献
658.
659.
《International Journal of Digital Earth》2013,6(2):185-195
Abstract Recent developments in space technology and exponential increase in demand of earth observation data from space have generated a requirement of a data processing environment, where users can discover the data and process, based on their requirements. Grid Services for Earth Observation Image Data Processing (GEOID) is proposed with a motivation to cater to future earth observation applications requirements of digital earth. This paper discusses the overview of the GEOID architecture, its deployment scenario, use-cases and simulation results. Core technologies used for implementation include Grid computing and Service Oriented Architecture. GEOID provides capability to address requirements of applications such as real-time monitoring, time series data processing and processing with user required quality to meet the requirements of end user applications. GEOID allows users to access the archive products or the raw satellite data stream and process their area of interest. Simulations show that applications such as time series analysis show considerable improvement in processing time by using GEOID. 相似文献
660.
《International Journal of Digital Earth》2013,6(11):901-917
Interpreting spatial data to derive information is a core task in the field of Geographic Information Science and Technology. A logical step following the collection of data in online repositories is to provide geoprocessing technology for analysing data online. Online geoprocessing technology can be employed for providing a specified set of tools in a theme-specific platform, documenting a model or workflow and making it widely available, automating recurring tasks or offering simple tools to a large user group. This systematic analysis of literature evaluates how much available online geoprocessing tools are being used for answering questions in specific application contexts. An initial set of articles is derived from a keyword-based search in the database Scopus. This set of articles is manually filtered to identify applications of online geoprocessing tools. The analysis of application-related articles shows that virtually all applications require further development of tools. Experts outside the spatial information science field are still underrepresented regarding the use of this technology. The required adaptation of technology for user tasks is identified as major barrier for the wide use of online geoprocessing. Further research needs to assess user tasks and how online geoprocessing can provide the required functions in a user-oriented manner. 相似文献