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131.
Jochen Schanze Johanna Trümper Cornelia Burmeister Dirk Pavlik Ivan Kruhlov 《Environmental Earth Sciences》2012,65(5):1405-1414
The paper presents a methodology on how to consistently deal with the future change and management options in integrated water
resources management (IWRM). It is based on a conceptual framework with a five step procedure for the formulation and analysis
of a so-called ‘parameterised regional futures’. Developing and testing the approach for IWRM is realised for the upper part
of the Western Bug River catchment (Ukraine). Special attention is paid to scenarios of change covering climate and land use.
The future regional climate is downscaled with the model CCLM. Land cover is projected after retrospective change detection
and the derivation of prospective algorithms. Parameters of the interrelations between land use and the water cycle are tackled
through using the concept of the model PWF-LU. The methodology is currently being tested to analyse the impacts of mid-term
regional change and management options on the water cycle of the catchment. 相似文献
132.
Stefan Lang Stefan Kienberger Dirk Tiede Michael Hagenlocher Lena Pernkopf 《制图学和地理信息科学》2014,41(3):214-226
The design of methods and tools to build adequate representations of complex geographical phenomena in a way that spatial patterns are emphasized is one of the core objectives of GIScience. In this paper, we build on the concept of geons as a strategy to represent and analyze latent spatial phenomena across different geographical scales (local, national, regional) incorporating domain-specific expert knowledge. Focusing on two types, we illustrate and exemplify how geons are generated and explored. So-called composite geons represent functional land-use classes, required for regional planning purposes. They are created via class modeling to translate interpretation schemes from mapping keys. Integrated geons, on the other hand, address abstract, yet policy-relevant phenomena such as societal vulnerability to hazards. They are delineated by regionalizing continuous geospatial data sets representing relevant indicators in a multidimensional variable space. Using the geon approach, we create spatially exhaustive sets of units, scalable to the level of policy intervention, homogenous in their domain-specific response, and independent from any predefined boundaries. From a GIScience perspective, we discuss either type of geons in a semantic hierarchy of geographic information constructs. Despite its validity for decision-making and its transferability across scales and application fields, the delineation of geons requires further methodological research to assess their statistical and conceptual robustness. 相似文献
133.
Geosimulation of urban growth and demographic decline in the Ruhr: a case study for 2025 using the artificial intelligence of cells and agents 总被引:1,自引:0,他引:1
The Ruhr is an “old acquaintance” in the discourse of urban decline in old industrialized cities. The agglomeration has to struggle with archetypical problems of former monofunctional manufacturing cities. Surprisingly, the image of a shrinking city has to be refuted if you shift the focus from socioeconomic wealth to its morphological extension. Thus, it is the objective of this study to meet the challenge of modeling urban sprawl and demographic decline by combining two artificial intelligent solutions: The popular urban cellular automaton SLEUTH simulates urban growth using four simple but effective growth rules. In order to improve its performance, SLEUTH has been modified among others by combining it with a robust probability map based on support vector machines. Additionally, a complex multi-agent system is developed to simulate residential mobility in a shrinking city agglomeration: residential mobility and the housing market of shrinking city systems focuses on the dynamic of interregional housing markets implying the development of potential dwelling areas. The multi-agent system comprises the simulation of population patterns, housing prices, and housing demand in shrinking city agglomerations. Both models are calibrated and validated regarding their localization and quantification performance. Subsequently, the urban landscape configuration and composition of the Ruhr 2025 are simulated. A simple spatial join is used to combine the results serving as valuable inputs for future regional planning in the context of multifarious demographic change and preceding urban growth. 相似文献
134.
Abstract The ultraviolet (UV) sensitivity of five species of freshwater zooplankton (three Cladocera, two Copepoda) were investigated. The animals were exposed to varying levels of UV‐radiation in a sunshine‐simulator and the UV doses for 10 and 50% mortality (LD10, LD50) were estimated using a dose‐response model. To place these doses in context they were compared with modelled clear‐sky surface UV irradiances in New Zealand. The cladocerans Daphnia carinata and Ceriodaphnia dubia were sensitive to levels of UVB irradiance of LD10 = 18–25 kJ m?2 and LD50 = 35–37 kJ m?2. These sensitivities are consistent with published values for other cladocera. In contrast a third cladoceran, Bosmina meridionalis, exhibited no higher mortality over the full range of the cumulative UVB‐doses used (3–40 kJ m?2) than controls receiving no UV exposure. The copepod Boeckella delicata showed the highest UV‐sensitivity of all organisms tested (LD10 = 7 kJ m?2, LD50 = 33 kJ m?2) whereas for Boeckella triarticulata, which was more heavily pigmented than B. delicata, no UV‐induced mortality was observed. Under natural conditions UV irradiances of up to 100 kJ m?2 day?1 can fall on the surface of New Zealand lakes. Although this is attenuated in natural waters, these data suggest that UVB irradiance may be a significant ecological variable to some zooplankton species. 相似文献
135.
Computer-controlled scanning electron microscopy is introduced as a faster, reliably and cost-reducing alternative to conventional electron microprobe analyses on kimberlite indicator minerals. The method is based on conventional scanning electron microscopy and energy dispersive X-ray spectrometry, but due to extended counting times, optimised settings and computer-controlled particle recognition valid data can be obtained on a low amount of operator and machine time. A comparison of the results between both methods yields that computer-controlled scanning electron microscopy is able to investigate major and minor element concentrations in indicator minerals with almost the same precision as the electron microprobe. 相似文献
136.
Susan A. Welch Andrew G. Christy Lloyd Isaacson Dirk Kirste 《Geochimica et cosmochimica acta》2009,73(1):44-177
Major, trace and rare earth element concentrations were measured in porewater, surface water and sediments at an acid sulfate soil site. The concentrations of La and Ce in porewater are up to 1-3 ppm. There is a strong correlation between REE concentration and acidity, except that the maximum concentrations were consistently found below the horizon of maximum acidity, associated with an increase in pH (to ca. 4) and change in mineralogy from jarosite-dominated to goethite-dominated mottles. Jarosite replacement by goethite is as expected with the rise in pH, which in turn is due to the occurrence of a fossil shell bed just below. The rare earth element patterns in the porewaters are enriched in the MREE with respect to Post-Archaean Australian Shale (PAAS). Measurements and calculations show that this is in accord with experiments on low-degree partial dissolution of jarosite, even when the jarosite itself is highly enriched in LREE. There is a clear fractionation in the patterns between the clay-rich soil matrix, which is slightly depleted in the LREE when normalized to PAAS (La/YbPAAS ∼0.5), and the secondary mineral phase jarosite, which is enriched in the LREE (La/YbPAAS = 15-50). The REE pattern in the porewater changes with the transition from jarosite- to goethite-rich mottles, becoming relatively more enriched in the LREE compared to the HREE, which is consistent with the incongruent dissolution of jarosite to form goethite and the release of greater amounts of jarosite REE to solution, including proportionately more of the jarosite-compatible LREE.Maximum surface water REE concentrations in acidic water were 100-200 ppb La and Ce. REE patterns in surface water were very similar to the porewater transition zone, enriched in the MREE, but asymmetric, relatively enriched in the LREE compared to the HREE. 相似文献
137.
Hadi Hajibeygi Jan Dirk Jansen Olwijn Leeuwenburgh Denis Voskov 《Computational Geosciences》2017,21(5-6):833-833
138.
Hilde Eggermont Oliver Heiri James Russell Mathias Vuille Leen Audenaert Dirk Verschuren 《Journal of Paleolimnology》2010,43(3):413-435
Fossil assemblages of chironomid larvae (non-biting midges) preserved in lake sediments are well-established paleothermometers
in north-temperate and boreal regions, but their potential for temperature reconstruction in tropical regions has never before
been assessed. In this study, we surveyed sub-fossil chironomid assemblages in the surface sediments of 65 lakes and permanent
pools in southwestern Uganda (including the Rwenzori Mountains) and central and southern Kenya (including Mount Kenya) to
document the modern distribution of African chironomid communities along the regional temperature gradient covered by lakes
situated between 489 and 4,575 m above sea level (a.s.l). We then combined these faunal data with linked Surface-Water Temperature
(SWTemp: range 2.1–28.1°C) and Mean Annual Air Temperature (MATemp: range 1.1–24.9°C) data to develop inference models for
quantitative paleotemperature reconstruction. Here we compare and discuss the performance of models based on different numerical
techniques [weighted-averaging (WA), weighted-averaging partial-least-squares (WA-PLS) and a weighted modern analogue technique
(WMAT)], and on subsets of lakes with varying gradient lengths of temperature and other environmental variables. All inference
models calibrated against MATemp have a high coefficient of determination (
r\textjack2 r_{\text{jack}}^{2} = 0.81–0.97), low maximum bias (0.84–2.59°C), and low root-mean-squared error of prediction (RMSEP = 0.61–1.50°C). The statistical
power of SWTemp models is generally weaker (
r\textjack2 r_{\text{jack}}^{2} = 0.77–0.95; maximum bias 1.55–3.73°C; RMSEP = 1.39–1.98°C), likely because the surface-water temperature data are spot measurements
failing to catch significant daily and seasonal variation. Models based on calibration over the full temperature gradient
suffer slightly from the limited number of study sites at intermediate elevation (2,000–3,000 m), and from the presence of
morphologically indistinguishable but ecologically distinct taxa. Calibration confined to high-elevation sites (>3,000 m)
has poorer error statistics, but is less susceptible to biogeographical and taxonomic complexities. Our results compare favourably
with chironomid-based temperature inferences in temperate regions, indicating that chironomid-based temperature reconstruction
in tropical Africa can be achieved. 相似文献
139.
Charline Giguet-Covex Fabien Arnaud Jérôme Poulenard Dirk Enters Jean-Louis Reyss Laurent Millet Jérome Lazzaroto Olivier Vidal 《Journal of Paleolimnology》2010,43(1):171-190
Sedimentological, geochemical and particle-size analyses were used to reconstruct the evolution of both trophic state and
hypolimnetic anoxia in Lake Bourget (French Alps) during the last century. Radionuclide dating (210Pb, 137Cs and 241Am) confirmed the annual rhythm of laminations in the upper sediment profile. In Lake Bourget, biochemical varves are triplets
composed of a diatom layer (spring lamina), a bio-precipitated calcite-rich layer (spring/summer lamina), and a layer rich
in organic matter and detrital particles (winter lamina). The onset of eutrophication and the first appearance of an anoxic
facies occurred simultaneously and were dated by laminae counting to AD 1943±1 year. Persistent anoxic conditions began in
AD 1960. Eutrophication is characterised by drastic increases in the flux of biogenic silica (mostly diatoms), lacustrine
organic matter, and larger calcite crystals (15–30 μm). The increase of organic matter also represents a marker of the onset
of anoxic conditions in the hypolimnion. Our results show that eutrophication was the main factor controlling anoxia in the
hypolimnion. This eutrophication was caused mostly by the inflow of untreated sewage effluents, and to a lesser extent, by
input of fertilizer-derived phosphorus during floods of the Rhone River and run-off from the lake catchment. The Rhone River,
however, can also be a source of re-oxygenation via underflows that originate during flood events. Oxygenation of the hypolimnion
is also controlled by low winter temperatures, which enable turnover of the lake. Thus, global warming, associated with a
forecasted reduction in precipitation, might reduce the efficiency of hypolimnetic re-oxygenation in Lake Bourget. 相似文献
140.
A simple box model of the circulation into and inside the ocean cavern beneath an ice shelf is used to estimate the melt rates
of Antarctic glaciers and ice shelves. The model uses simplified cavern geometries and includes a coarse parameterization
of the overturning circulation and vertical mixing. The melting/freezing physics at the ice shelf/ocean interface are those
usually implemented in high-resolution circulation models of ice shelf caverns. The model is driven by the thermohaline inflow
conditions and coupling to the heat and freshwater exchanges at the sea surface in front of the cavern. We tune the model
for Pine Island Glacier and then apply it to six other major caverns. The dependence of the melting rate on thermohaline conditions
at the ice shelf front is investigated for this set of caverns, including sensitivity studies, alternative parameterizations,
and warming scenarios. An analytical relation between the melting rate and the inflow temperature is derived for a particular
model version, showing a quadratic dependence of basal melting on small values of the temperature of the inflow, which changes
to a linear dependence for larger values. The model predicts melting at all ice shelf bases in agreement with observations,
ranging from below a meter per year for Ronne Ice Shelf to about 25 m/year for the Pine Island Glacier. In a warming scenario
with a one-degree increase of the inflow temperature, the latter glacier responds with a 1.4-fold increase of the melting
rate. Other caverns respond by more than a tenfold increase, as, e.g., Ronne Ice Shelf. The model is suitable for use as a
simple fast module izn coarse large-scale ocean models. 相似文献