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281.
Modeling biodiversity benefits and external costs from a keystone predator reintroduction policy 总被引:1,自引:1,他引:0
In this paper, an economic model was constructed to determine the optimal wolf population and distribution across the Northern Rocky Mountains. Both ecological and economic concepts were incorporated in an implicitly spatial social welfare maximization problem. This interdisciplinary model relies on multiple data sources, including current wolf population and distribution information, opportunity cost to local landowners, and contingent valuation studies to determine willingness-to-pay for wolves. Economic models tend to externalize ecological concerns and ecological models often omit the complex human dimensions of conservation policy. Accordingly, this model can serve as a guide for integrating best practices from both fields. The model presented here is sufficiently general to apply to wolves in other ecosystems and to other highly interacting species such as beavers and bison. The Northern Rocky Mountain wolf was used as an example of how this economic model works, but this model can be applied far more broadly. 相似文献
282.
During long-lived basaltic eruptions, overflows from lava channels and breaching of channel levées are important processes
in the development of extensive 'a'ā lava flow-fields. Short-lived breaches result in inundation of areas adjacent to the
main channel. However, if a breach remains open, lava supply to the original flow front is significantly reduced, and flow-field
widening is favoured over lengthening. The development of channel breaches and overflows can therefore exert strong control
over the overall flow-field development, but the processes that determine their location and frequency are currently poorly
understood. During the final month of the 2008–2009 eruption of Mt. Etna, Sicily, a remote time-lapse camera was deployed
to monitor events in a proximal region of a small ephemeral lava flow. For over a period of ~10 h, the flow underwent changes
in surface elevation and velocity, repeated overflows of varying vigour and the construction of a channel roof (a required
prelude to lava tube formation). Quantitative interpretation of the image sequence was facilitated by a 3D model of the scene
constructed using structure-from-motion computer vision techniques. As surface activity waned during the roofing process,
overflow sites retreated up the flow towards the vent, and eventually, a new flow was initiated. Our observations and measurements
indicate that flow surface stagnation and flow inflation propagated up-flow at an effective rate of ~6 m h−1, and that these processes, rather than effusion rate variations, were ultimately responsible for the most vigorous overflow
events. We discuss evidence for similar controls during levée breaching and channel switching events on much larger flows
on Etna, such as during the 2001 eruption. 相似文献
283.
Involvement in scientifically structured habitat monitoring is a relatively new concept to the peoples of Torres Strait. The approach we used was to focus on awareness, and to build the capacity of groups to participate using Seagrass-Watch as the vehicle to provide education and training in monitoring marine ecosystems. The project successfully delivered quality scientifically rigorous baseline information on the seasonality of seagrasses in the Torres Strait—a first for this region. 相似文献
284.
Andrea E. Gaughan Michael W. Binford Jane Southworth 《Applied geography (Sevenoaks, England)》2009,29(2):212-223
The Angkor basin of Cambodia, the site of the great Angkor temple complex, has experienced explosive tourism growth since the 1993 onset of national political stability and renewed international investment, which in turn has driven increasing demand for water, wood, and biomass fuel, and rapid and extensive land-use and land-cover change. We use multi-temporal Landsat imagery (1989–2005) to describe the rate and extent of land-cover change throughout the Angkor basin. While 50% of the landscape remained in rice agriculture it is notable that a larger proportion of the area was deforested (23.4%) than experienced forest regrowth (4.9%). Most forest loss occurred between the Angkor temple complex and Phnom Kulen National Park, and was due in part to charcoal production to serve the tourist industry, and also conversion to permanent agriculture. The small area of forest increase was concentrated along the eastern boundary of the main Angkor complex. The interplay among global (tourism, climate), regional (national policies, large-river management), and local (construction and agriculture, energy and water sources to support the tourism industry) factors drives a distinctive but complex pattern of land-use and land-cover change. 相似文献
285.
286.
Ricketts Hein J Watts D 《Irish geography : bulletin of the Geographical Society of Ireland》2010,43(2):135-147
Recent changes in local food supply systems have attracted substantial research interest, but little consideration has been paid to exactly where they occur. This article combines data from three studies to compare local food system development in England, Wales, Scotland and Ireland using a single index of food relocalisation, thereby exploring the usefulness of the Index across different social and political contexts. Four diagnostic indicators suggest that local food systems in the south west of Ireland and Britain are particularly well developed. The Index itself is a useful tool for making international comparisons, being easy to replicate and allowing the integration of different data sets. Perhaps its greatest utility is that it opens up new avenues for further research. 相似文献
287.
Page B McKenzie J McIntosh R Baylis A Morrissey A Calvert N Haase T Berris M Dowie D Shaughnessy PD Goldsworthy SD 《Marine pollution bulletin》2004,49(1-2):33-42
In recent years, Australian governments and fishing industry associations have developed guiding principles aimed at reducing the impact of fishing on non-target species and the benthos and increasing community awareness of their efforts. To determine whether they reduced seal entanglement in lost fishing gear and other marine debris, we analysed Australian sea lion and New Zealand fur seal entanglement data collected from Kangaroo Island, South Australia. Contrary to our expectations, we found that entanglement rates did not decrease in recent years. The Australian sea lion entanglement rate (1.3% in 2002) and the New Zealand fur seal entanglement rate (0.9% in 2002) are the third and fourth highest reported for any seal species. Australian sea lions were most frequently entangled in monofilament gillnet that most likely originated from the shark fishery, which operates in the region where sea lions forage--south and east of Kangaroo Island. In contrast, New Zealand fur seals were most commonly entangled in loops of packing tape and trawl net fragments suspected to be from regional rock lobster and trawl fisheries. Based on recent entanglement studies, we estimate that 1478 seals die from entanglement each year in Australia. We discuss remedies such as education programs and government incentives that may reduce entanglements. 相似文献
288.
289.
Carbonate Assimilation at Merapi Volcano, Java, Indonesia: Insights from Crystal Isotope Stratigraphy 总被引:2,自引:0,他引:2
Chadwick Jane P.; Troll Valentin R.; Ginibre Catherine; Morgan Daniel; Gertisser Ralf; Waight Tod E.; Davidson Jon P. 《Journal of Petrology》2007,48(9):1793-1812
Recent basaltic andesite lavas from Merapi volcano contain abundant,complexly zoned, plagioclase phenocrysts, analysed here fortheir petrographic textures, major element composition and Srisotope composition. Anorthite (An) content in individual crystalscan vary by as much as 55 mol% (An40–95) across internalresorption surfaces with a negative correlation between highAn mol% (>70), MgO wt% and FeO wt%. In situ Sr isotope analysesof zoned plagioclase phenocrysts show that the 87Sr/86Sr ratiosof individual zones range from 0·70568 to 0·70627.The upper end of this range is notably more radiogenic thanthe host basaltic andesite whole-rocks (< 0·70574).Crystal zones with the highest An content have the highest 87Sr/86Srvalues, requiring a source or melt with elevated radiogenicSr, rich in Ca and with lower Mg and Fe. Recent Merapi eruptiverocks contain abundant xenoliths, including metamorphosed volcanoclasticsediment and carbonate country rock (calc-silicate skarns) analysedhere for petrographic textures, mineralogy, major element compositionand Sr isotope composition. The xenoliths contain extremelycalcic plagioclase (up to An100) and have whole-rock 87Sr/86Srratios of 0·70584 to 0·70786. The presence ofthese xenoliths and their mineralogy and geochemistry, coupledwith the 87Sr/86Sr ratios observed in different zones of individualphenocrysts, indicate that magma–crust interaction atMerapi is potentially more significant than previously thought,as numerous crystal cores in the phenocrysts appear to be inheritedfrom a metamorphosed sedimentary crustal source. This has potentiallysignificant consequences for geochemical mass-balance calculations,volatile saturation and flux and eruptive behaviour at Merapiand similar island arc volcanic systems elsewhere. KEY WORDS: assimilation; isotopes; Merapi; xenolith; calc-silicate 相似文献
290.
Local policies can play an important role in establishing a context that shapes vulnerability and influences subsequent recovery
of lifelines under the natural hazards of extreme wind and seismic events. External factors, such as access availability,
have long been known to influence the rate of restoration of utility systems following blackouts. Thus, since system performance
takes place within a socio-technical-political context, it can be anticipated that selected local policies may also influence
either the geographic extent of damage or the rate of restoration or both. This project empirically validates the assumption
that selected local non-design policies establish a context that significantly (measurably) influences system functionality
in terms of spatial extent and duration of outage. 相似文献