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61.
In order to assess the net effect and relative importance of geomorphic processes at two natural woodland sites in southeast Australia, 100 small tiles were placed on the soil surface in 1979 and their movement was monitored over the course of nearly three decades. Rates of tile burial and other tile displacement were considerable but also markedly random, being largely inconsistent with expected patterns of displacement by orthodox creep and rainwash processes. This included substantial upslope displacement and burial depths that ranged from zero to 5 cm. We suggest that such turbulent transport in the topsoil has mostly been caused by the direct and indirect transfer of soil and clasts by animals and plants (i.e. bioturbation). In addition to direct evidence of biota interacting with tiles, the effectiveness of bioturbation at our sites has been well established and the overall tile burial rate of 0·25 to 0·4 mm yr?1 is comparable to rates of surface mounding. Patterns of tile movement are generally consistent with soils‐geomorphic theory regarding the biomantle and bioturbation‐driven stonelayer formation, and provide further evidence that soil transfer and slope movement, in many situations, are markedly random and complex processes. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Effects of short-term exposure to sedimentation and diuron, separately and in combination, on the photophysiology and survival of crustose coralline algae (CCA) were examined in controlled time-course experiments, using pulse-amplitude modulation (PAM) chlorophyll fluorometry. These experiments indicated that the effects of sediments and diuron, when applied in isolation, were often reversible, with recovery time dependent upon sediment type and diuron concentration. Exposure to fine (<63 microm grain size), nutrient-rich estuarine sediments reduced effective quantum yields (Delta F/F(m')) of photosystem II in CCA species more than exposure to the same amount of fine (<63 microm grain size) calcareous sediments. Significant inhibition of photosynthesis (Delta F/F(m')) was also observed at diuron concentrations > or =2.9 microg L(-1). Fine estuarine sediments in combination with 0.79 microg L(-1) dissolved diuron, caused yields (Delta F/F(m')) to drop by 60% compared with controls after 24 h. The combined exposure to sediments and diuron also retarded recovery, thus Delta F/F(m') values were still only 60% of the controls after 9 days recovery in clean seawater. Mortality of CCA was observed in some fragments treated with combinations of sediment and diuron. Our results suggest that sediment deposition and exposure to diuron can negatively affect the photosynthetic activity of CCA, with sedimentation stress being significantly enhanced by the presence of trace concentrations of diuron. 相似文献
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The "bioeffect assessment index" (BAI) is based on the integration of several pathological endpoints measured in the liver of European flounder (Platichthys flesus (L.)) during a long term study of biological effects of pollution in the German Bight. The BAI represents a modification of the "health assessment index" since it includes solely validated biomarkers reflecting toxically induced alterations at different levels of biological organisation in order to quantify the effects of environmental pollution. The concept of the BAI is based on the observation of progressive deleterious effects from early responses to late effects. Specific "key events" were detected, representing progressive stages of functional deterioration. The biomarkers selected from a whole battery of cellular markers for the BAI calculation reflect deleterious effects of various classes of contaminants such as heavy metals, organochlorines, pesticides, PAHs, and therefore reflect general toxicity in an integrative manner. Selected biomarkers were: lysosomal perturbations (reduced membrane stability), storage disorders (lipid accumulation) as early markers for toxic effects of liver cells, and the size of macrophage aggregates and their acid phosphatase activity. The latter two markers are indicative for the modulation of non-specific immune response which represents longer time scale responses after chronic exposure. 相似文献
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Geoff Woolcock 《The Australian geographer》2013,44(1):23-39
Knowing where sports talent is produced is fundamental to identifying spatial factors in talent production and to assist with talent identification. This research develops spatial analysis methods—the ‘Talent Tracker’—to harness geographical information systems and identify regions that are over- and under-producing sports talent. The approach focuses on the professional Australian Football League (AFL), using data sourced from the AFL itself and other sources, to identify differences in regional ‘talent yield’ based on junior participation. Data from AFL draft records, informants and secondary sources identified the place of junior talent development for the 1290 players who were drafted and played at least one game of senior AFL football in the period 1997–2010. AFL national census data identified junior participation for 94 specified regions for the period 2002–09. AFL talent was assigned to these regions by using ArcGIS procedures, and the datasets synthesised to produce tables and maps of talent yield by participation for each of the 94 AFL regions. The results demonstrate the power of contemporary spatial analysis to open up new research methods for studies into sports talent production and identification. Clear spatial patterns emerge in talent yield at both the national and metropolitan scales. The results provide numerous avenues for further research to explore determining factors for the spatial patterns identified. 相似文献
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Pavel SPURNÝ Philip A. BLAND Lukáš SHRBENÝ Jiří BOROVIČKA Zdeněk CEPLECHA Andrew SINGELTON Alex W. R. BEVAN David VAUGHAN Martin C. TOWNER Terence P. McCLAFFERTY Ralf TOUMI Geoff DEACON 《Meteoritics & planetary science》2012,47(2):163-185
Abstract– We report an analysis of the first instrumentally observed meteorite fall in Australia, which was recorded photographically and photoelectrically by two eastern stations of the Desert Fireball Network (DFN) on July 20, 2007. The meteoroid with an initial mass of 22 kg entered the atmosphere with a low speed of 13.36 km s?1 and began a luminous trajectory at an altitude of 62.83 km. In maximum, it reached ?9.6 absolute magnitude and terminated after a 5.7 s and 64.7 km long flight at an altitude of 29.59 km with a speed of 5.8 km s?1. The angle of the atmospheric trajectory to the Earth’s surface was 30.9°. The first organized search took place in October 2008 and the first meteorite (150 g) was found 97 m southward from the predicted central line at the end of the first day of searching (October 3, 2008). The second stone (174 g) was recovered 39 m northward from the central line, both exactly in the predicted mass limits. During the second expedition in February 2009, a third fragment of 14.9 g was found again very close (~100 m) from the predicted position. Total recovered mass is 339 g. The meteorite was designated Bunburra Rockhole (BR) after a nearby landscape structure. This first DFN sample is an igneous achondrite. Initial petrography indicated that BR was a brecciated eucrite but detailed analyses proved that BR is not a typical eucrite, but an anomalous basaltic meteorite ( Bland et al. 2009 ). BR was delivered from an unusual, Aten type orbit (a < 1 AU) where virtually the entire orbit was contained within Earth’s orbit. BR is the first achondrite fall with a known orbit and it is one of the most precise orbits ever calculated for a meteorite dropping fireball. 相似文献