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531.
532.
Andrzej Baran John Telting Roy Østensen Maciej Winiarski Marek Drożdż Dorota Kozieł Mike Reed Raquel Oreiro Roberto Silvotti Michał Siwak Uli Heber Peter Papics 《Astrophysics and Space Science》2010,329(1-2):199-203
We present early results of the application of a method which uses multicolor photometry and spectroscopy for ? discrimination. This method has been successfully applied to the pulsating hot subdwarf Balloon?090100001. Here we apply the method to QQ?Vir (PG1325+101). This star was observed spectroscopically and photometrically in 2008. Details on spectroscopy can be found in Telting et al. (Astrophys. Space Sci. 2010, this volume), while photometry and preliminary results on ? discrimination are provided here. The main aim of this work was to compare the value of the ? parameter derived for the main mode in QQ?Vir to previously published values derived by using different methods. 相似文献
533.
A COMPARISON OF EASTERN AND WESTERN HONG KONG PHYTOPLANKTON FROM WEEKLY SAMPLES (1997-1999) 总被引:3,自引:0,他引:3
Weekly phytoplankton samples were taken from western Hong Kong (Lamma) from Jan. 1997 to Dec. 1999 and from Port Shelter in
Eastern Hong Kong from January 1998 to December 1999. During that time diatom blooms occurred repeatedly at both sites but
never in synchrony. One species would bloom at one site and then weeks later it or another species would bloom at the other
site; while the 1998 red tide of the mucus producing dinoflagellateGymnodinium mikimotoi occurred at both sites. It first occurred at the Port Shelter site in March and did not appear at the Lamma site until April.
With the single exception of this species, no other dinoflagellate reached bloom concentrations at the Lamma site. In addition,
dinoflagellate abundance at the Lamma site was significantly lower (P<0.05) than that at the Port Shelter site. This was correlated
with a significantly higher turbidity (i. e. low Secchi transparency) and higher turbulence (stronger currents) at the Lamma
site.
Annual variation in surface temperature correlated with total surface phytoplankton abundance at both our sample sites. Phytoplankton
abundance increased in spring as water temperatures warmed. In fall, as surface water temperatures began to decline and the
monsoon rains became less frequent there was a reduction in phytoplankton abundance associated with the reduction in temperature
and light. Because so many variables co-occur with temperature (e. g. the amount of rainfall light intensity and light duration
etc.) it is not possible to cite temperature as the causal factor associated weth controlling phytoplankton abundance at our
two sample sites.
Our data support the rather controversial notion that percentage-wise, there are relatively more harmful bloom forming species
in nutrient-rich coastal waters than there are in the world's oceans. 16% of the dinoflagellate species and 10.3% of the diatom
species observed at our two sample sites were classed as harmful. These percentages were higher than those cited by Sournia
(1995) for the worlds oceans (9.6% and 6.8% respectively). This raises the possibility that there are relatively more toxic
species in the nutrient-rich coastal waters of the world than there are in the mid ocean nutrient-poor areas of the world.
Some reasons for this are briefly discussed. 相似文献
534.
This paper examines the spatial and social distribution of the fear of crime and the relationships of such fear with aspects of the environment. Through an analysis of a questionnaire survey conducted in a variety of areas in Stoke-on-Trent in the English Midlands, it considers both the causes of the fear of crime and the associations that have been identified with other dimensions shaping vulnerability. It concludes by offering some guidance on how to address the differences between those populations who fear crime most and those who are most vulnerable. 相似文献
535.
Imaging short period variations in lava flux 总被引:1,自引:1,他引:1
Short period (e.g. <1 h) variations in lava effusion rate have been detected previously on Mount Etna, Sicily, but the causes
and effects of such changes are poorly understood because of difficulties in obtaining suitably high frequency measurements
over long periods. Here, we report short period flux variations in active lava flows, recorded in dense time series imagery
over a 7-night period using modified remote trail cameras. The sequences of night-time images show significant pulses of enhanced
incandescence, interpreted as short period increases in lava flux, travelling down-channel at velocities of ∼10–20 m min−1. Pulse generation decreased from an average of one pulse per hour on the first night to approximately one per night within
a few nights. Effusion rate changes on these timescales are considered to reflect instabilities in magma ascent and, consequently,
could provide insight into subsurface flow processes. 相似文献
536.
Kathleen M. Swanson Judith Z. Drexler David H. Schoellhamer Karen M. Thorne Mike L. Casazza Cory T. Overton John C. Callaway John Y. Takekawa 《Estuaries and Coasts》2014,37(2):476-492
Salt marsh faunas are constrained by specific habitat requirements for marsh elevation relative to sea level and tidal range. As sea level rises, changes in relative elevation of the marsh plain will have differing impacts on the availability of habitat for marsh obligate species. The Wetland Accretion Rate Model for Ecosystem Resilience (WARMER) is a 1-D model of elevation that incorporates both biological and physical processes of vertical marsh accretion. Here, we use WARMER to evaluate changes in marsh surface elevation and the impact of these elevation changes on marsh habitat for specific species of concern. Model results were compared to elevation-based habitat criteria developed for marsh vegetation, the endangered California clapper rail (Rallus longirostris obsoletus), and the endangered salt marsh harvest mouse (Reithrodontomys raviventris) to determine the response of marsh habitat for each species to predicted >1-m sea-level rise by 2100. Feedback between vertical accretion mechanisms and elevation reduced the effect of initial elevation in the modeled scenarios. Elevation decreased nonlinearly with larger changes in elevation during the latter half of the century when the rate of sea-level rise increased. Model scenarios indicated that changes in elevation will degrade habitat quality within salt marshes in the San Francisco Estuary, and degradation will accelerate in the latter half of the century as the rate of sea-level rise accelerates. A sensitivity analysis of the model results showed that inorganic sediment accumulation and the rate of sea-level rise had the greatest influence over salt marsh sustainability. 相似文献
537.
Climate change is a global phenomenon, and its outcomes affect societies around the world. So far, however, studies on media representations of climate change have mostly concentrated on Western societies. This paper goes beyond this limited geographical scope by presenting a comparative analysis of issue attention in 27 countries. The sample includes, among others, countries that have committed themselves to greenhouse gas emission reductions under the Kyoto Protocol such as Germany as well as countries that are strongly affected by the consequences of climate change like India. In a first step, it describes the development of media attention for climate change in these countries from 1996 to 2010. Second, it compares the amount of media attention and explores whether it corresponds with indicators measuring the relevance of climate change and climate policies for a country. The analyses show that climate change coverage has increased in all countries. Still, overall media attention levels, as well as the extent of growth over time, differ strongly between countries. Media attention is especially high in carbon dependent countries with commitments under the Kyoto Protocol. 相似文献
538.
539.
Sandra McLaren Mike Sandiford† W. James Dunlap Ian Scrimgeour‡ Dorothy Close‡ Christine Edgoose‡ 《Basin Research》2009,21(3):315-334
The Centralian Superbasin in central Australia is one of the most extensive intracratonic basins known from a stable continental setting, but the factors controlling its formation and subsequent structural dismemberment continue to be debated. Argon thermochronology of K-feldspar, sensitive to a broad range of temperatures (∼150 to 350 °C), provides evidence for the former extent and thickness of the superbasin and points toward thickening of the superbasin succession over the now exhumed Arunta Region basement. These data suggest that before Palaeozoic tectonism, there was around 5–6 km of sediment present over what is now the northern margin of the Amadeus Basin, and, if the Centralian superbasin was continuous, between 6 and 8 km over the now exhumed basement. 40 Ar/39 Ar data from neoformed fine-grained muscovite suggests that Palaeozoic deformation and new mineral growth occurred during the earliest compressional phase of the Alice Springs Orogeny (ASO) (440–375 Ma) and was restricted to shear zones. Significantly, several shear zones active during the late Mesoproterozoic Teapot Orogeny were not reactivated at this time, suggesting that the presence of pre-existing structures was not the only controlling factor in localizing Palaeozoic deformation. A range of Palaeozoic ages of 440–300 Ma from samples within and external to shear zones points to thermal disturbance from at least the early Silurian through until the late Carboniferous and suggests final cooling and exhumation of the terrane in this interval. The absence of evidence for active deformation and/or new mineral growth in the late stages of the ASO (350–300 Ma) is consistent with a change in orogenic dynamics from thick-skinned regionally extensive deformation to a more restricted localized high-geothermal gradient event. 相似文献
540.
Mike Warner 《Geophysical Journal International》1987,89(1):21-26
Summary. Conventional migration of deep seismic reflection data often produces disappointingly poor results even when the original unmigrated data are of high quality and are relatively noise free. Surprisingly, deep data often subjectively appear to be best migrated at velocities which are up to 50% less than appropriate interval velocities derived from crustal refraction experiments or directly from stacking velocities. The explanation for this behaviour is that near surface features distort and attenuate the seismic wave field and produce apparent discontinuities in deep reflections. Since these discontinuities are spurious they are not associated with the appropriate large diffractions which real discontinuities at depth would produce. During the process of migration reflections are invented in order to cancel out the missing diffractions thereby producing a "smiley" section which appears overmigrated. Since the lateral extent of individual smiles increases with increasing migration velocity, increasing two-way-time, and increasing seismic wavelength, the effect" is almost unnoticeable on conventional shallow seismic data but is overwhelming for deep crustal data. 相似文献