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191.
192.
This study examined whether buried organic matter in the form of seagrass influenced colonization by the corophiid amphipod Paracorophium excavatum in an intertidal sandflat. Laboratory manipulations were compared to results from field studies to determine the role of hydrodynamics in mediating the effects of the organic matter. At levels of organic loading greater than 1% of sediment dry weight, size frequency effects and decreases in numbers of colonizers occurred in still water conditions. In the field, however, at levels of organics up to 2% of sediment dry weight, only size-frequency effects were observed. A change in hydrodynamic conditions and the influence of this on sediment geochemistry is suggested as the most reasonable explanation for the disparity in colonization both between sites in the field and between laboratory and field manipulations. Two effects of organics upon corophiid amphipod colonization are proposed: a lower level of organic loading that can lead to a greater proportion of juveniles in the colonizing population and a higher level of organics that can lead to a decrease in the numbers of amphipods colonizing. The threshold at which these effects take place is modulated by the hydrodynamics of the environment. The same organic addition can therefore have different effects upon colonization across a tidal flat, which is dependent upon the variation in hydrodynamics 相似文献
193.
Anjana Khatwa Ford 《Proceedings of the Geologists' Association. Geologists' Association》2019,130(3-4):507-521
World Heritage Sites have a duty, through educational and information programmes, to strengthen appreciation and respect by their peoples of the cultural and natural heritage of that site. The Jurassic Coast World Heritage Site (JCWHS) showcases nearly 185 million years of Earth’s history across 95 miles of coast and exemplifies some of the most spectacular rocks, fossils and landforms in the world. However, imparting these values to non-specialist audiences of all ages, abilities and needs provides unique challenges and opportunities. A critical factor for success in addressing such a wide audience is ensuring that content is relevant, meaningful and focused on the expectations of the end user. In this paper we present our learning framework that is based around two approaches. Firstly, we map out the needs and expectations of each of our four core audience groups and set out guidelines for who we should aim our content at and how that should be delivered. Secondly, we set out three pathways (Inspire, Curious and Motivated) through which a person may choose to engage with the Jurassic Coast. We argue that if our tailored content and experiences can resonate with a person at an emotional and intellectual level, they will ultimately become devoted to the Jurassic Coast. Through empowering a community of people who understand and appreciate the geoheritage of the Jurassic Coast, they can become advocates and champions for its protection and conservation in the future. 相似文献
194.
Gerrit J. Meijer David Muir Wood Jonathan A. Knappett Glyn A. Bengough Teng Liang 《国际地质力学数值与分析法杂志》2019,43(3):684-707
Plant roots can help to stabilise slopes. Existing analytical models to predict their mechanical contribution are however limited: they typically focus on the ultimate limit state, employ various empirical factors, and ignore much of the underlying root-soil interaction. A new model was developed based on large deflection Euler-Bernoulli elastic beam theory that can be used to study the mobilisation of root strength under various loading conditions (direct shear and pull-out). Both lateral and axial loading of the root by the soil were incorporated, based on existing methodologies for foundation piles (p-y and t-z curves). The model is able to take the key parameters into account (root biomechanical properties, root architectural properties, and soil properties) while remaining quick to solve using a numerical boundary value problem solver. The model was compared with experimental direct shear test data using various root analogues (rubber, plastic, and wood) in dry sand with various densities and effective stress levels and was able to accurately predict the measured shear force-displacement behaviour. Comparison with experimentally measured pull-out force-displacement curves using rubber and wooden root analogues with various architectures in dry and partially saturated sands was also satisfactory. In the future, this model can aid with addressing long-standing problems in the root-reinforcement community: quantifying the effect of (sequential) mobilisation of root strength in direct shear, the effect of the angle at which the root crosses a shear plane, the effect of root topology on root-reinforcement or the effect of root bending, and root shear shear forces on root-reinforcement. 相似文献
195.
Michele Ford 《Singapore journal of tropical geography》2008,29(2):130-132
196.
Donna J. Shillington Nicky White Timothy A. Minshull Glyn R.H. Edwards Stephen M. Jones Rosemary A. Edwards Caroline L. Scott 《Earth and Planetary Science Letters》2008,265(3-4):360-378
Subsidence analysis of the eastern Black Sea basin suggests that the stratigraphy of this deep, extensional basin can be explained by a predominantly pure-shear stretching history. A strain-rate inversion method that assumes pure-shear extension obtains good fits between observed and predicted stratigraphy. A relatively pure-shear strain distribution is also obtained when a strain-rate inversion algorithm is applied that allows extension to vary with depth without assuming its existence or form. The timing of opening of the eastern Black Sea, which occupied a back-arc position during the closure of the Tethys Ocean, has also been a subject of intense debate; competing theories called for basin opening during the Jurassic, Cretaceous or Paleocene/Eocene. Our work suggests that extension likely continued into the early Cenozoic, in agreement with stratigraphic relationships onshore and with estimates for the timing of arc magmatism. Further basin deepening also appears to have occurred in the last ~ 20 myr. This anomalous subsidence event is focused in the northern part of the basin and reaches its peak at ~ 15–10 Ma. We suggest that this comparatively localized shortening is associated with the northward movement of the Arabian plate. We also explore the effects of paleowater depth and elastic thickness on the results. These parameters are controversial, particularly for deep-water basins and margins, but their estimation is a necessary step in any analysis of the tectonic subsidence record stored in stratigraphy. 相似文献
197.
Foreword to the special issue: climate change impacts, adaptation and vulnerability in the Arctic 总被引:1,自引:0,他引:1
The Arctic climate is changing, carrying wide-ranging implications for indigenous and non-indigenous inhabitants, businesses, industry and government across the circumpolar region. The latest scientific assessments indicate that change is happening faster than previously thought, and that the Arctic will continue to experience dramatic climate change in the future. This special edition of Polar Research brings together nine papers on climate change impacts, adaptation and vulnerability in the Arctic, providing important insights on the nature of the risks and opportunities posed by climate change in the circumpolar region, highlighting opportunities for policy response and providing insights on how to conduct effective climate change research with Arctic communities. 相似文献
198.
A series of 707 measurements at Masaya in 2005, 2006, and 2007 reveals that SO2 emissions 15km downwind of the active vent appear to be ~33% to ~50% less than those measured only 5km from the vent. Measurements
from this and previous studies indicate that dry deposition of sulfur from the plume and conversion of SO2 to sulfate aerosols within the plume each may amount to a maximum of 10% loss, and are not sufficient to account for the
larger apparent loss measured. However, the SO2 measurement site 15km downwind is located on a ridge over which local trade winds, and the entrained plume, accelerate. Greater
wind speeds cause localized dilution of the plume along the axis of propagation. The lower concentrations of SO2 measured on the ridge therefore lead to calculations of lower fluxes when calculated at the same plume speed as measurements
from only 5km downwind, and is responsible for the apparent loss of SO2. Due to the importance of SO2 emission rates with respect to hazard mitigation, petrologic studies, and sulfur budget calculations, measured fluxes of
SO2 must be as accurate as possible. Future campaigns to measure SO2 flux at Masaya and similar volcanoes will require individual plume speed measurements to be taken at each flux measurement
site to compensate for dilution and subsequent calculation of lower fluxes. This study highlights the importance of a comprehensive
understanding of a volcano’s interaction with its surroundings, especially for low, boundary layer volcanoes. 相似文献
199.
Attenuation Tomography of the Yellow Sea/Korean Peninsula from Coda-source normalized and direct Lg Amplitudes 总被引:1,自引:0,他引:1
Sean R. Ford William S. Phillips William R. Walter Michael E. Pasyanos Kevin Mayeda Douglas S. Dreger 《Pure and Applied Geophysics》2010,167(10):1163-1170
We invert for regional attenuation of the crustal phase Lg in the Yellow Sea/Korean Peninsula (YSKP) using three different amplitude attenuation tomography methods. The first method solves for source, site, and path attenuation. The second method uses a scaling relationship to set the initial source amplitude and interpret the source term after inversion. The third method implements a coda-derived source spectral correction. By comparing methods with slightly different assumptions we are able to make a more realistic assessment of the uncertainties in the resulting attenuation maps than is obtainable through formal error analysis alone. We compare the site, source and path-terms produced by each method and comment on attenuation, which correlates well with tectonic and topographic features in the region. Source terms correlate well with each other and with magnitude. Site terms are similar except for two stations that are located in a region that has the greatest difference in path term, which demonstrates the site/path trade-off. Another region of path term difference has the fewest crossing paths, where the tomography method employing the coda-derived spectral correction may perform more accurately since it is not as susceptible to the source/path trade-off. The Bohai Bay basin, an area of extension, is a region of high attenuation, and regions of low attenuation occur along topographic highs located in the Da-xin-an-ling and Changbai Mountains and Mount Taishan. 相似文献
200.