全文获取类型
收费全文 | 124篇 |
免费 | 3篇 |
专业分类
测绘学 | 10篇 |
大气科学 | 26篇 |
地球物理 | 23篇 |
地质学 | 33篇 |
海洋学 | 3篇 |
天文学 | 21篇 |
自然地理 | 11篇 |
出版年
2020年 | 1篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 9篇 |
2015年 | 2篇 |
2014年 | 11篇 |
2013年 | 4篇 |
2012年 | 8篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 4篇 |
2006年 | 8篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1986年 | 1篇 |
1983年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
1958年 | 1篇 |
1957年 | 1篇 |
1953年 | 1篇 |
排序方式: 共有127条查询结果,搜索用时 15 毫秒
1.
Nicolaj K. Larsen Laura B. Levy Astrid Strunk Anne Sofie Sndergaard Jesper Olsen Torben L. Lauridsen 《Boreas: An International Journal of Quaternary Research》2019,48(3):551-562
Local glaciers and ice caps (GICs) comprise only ~5.4% of the total ice volume, but account for ~14–20% of the current ice loss in Greenland. The glacial history of GICs is not well constrained, however, and little is known about how they reacted to Holocene climate changes. Specifically, in North Greenland, there is limited knowledge about past GIC fluctuations and whether they survived the Holocene Thermal Maximum (HTM, ~8 to 5 ka). In this study, we use proglacial lake records to constrain the ice‐marginal fluctuations of three local ice caps in North Greenland including Flade Isblink, the largest ice cap in Greenland. Additionally, we have radiocarbon dated reworked marine molluscs in Little Ice Age (LIA) moraines adjacent to the Flade Isblink, which reveal when the ice cap was smaller than present. We found that outlet glaciers from Flade Isblink retreated inland of their present extent from ~9.4 to 0.2 cal. ka BP. The proglacial lake records, however, demonstrate that the lakes continued to receive glacial meltwater throughout the entire Holocene. This implies that GICs in Finderup Land survived the HTM. Our results are consistent with other observations from North Greenland but differ from locations in southern Greenland where all records show that the local ice caps at low and intermediate elevations disappeared completely during the HTM. We explain the north–south gradient in glacier response as a result of sensitivity to increased temperature and precipitation. While the increased temperatures during the HTM led to a complete melting of GICs in southern Greenland, GICs remained in North Greenland probably because the melting was counterbalanced by increased precipitation due to a reduction in Arctic sea‐ice extent and/or increased poleward moisture transport. 相似文献
2.
Anita Enmark Thomas Berkefeld Oskar von der Lühe Torben Andersen 《Experimental Astronomy》2006,21(2):87-99
A simulation model of the adaptive optics of the German Vacuum Tower Telescope (VTT), Observatorio del Teide, Tenerife, is
presented. The model uses modules from the integrated model of the Euro50 extremely large telescope, and includes submodels
of a Shack-Hartmann wavefront sensor, a de-formable mirror, a tip-tilt mirror, high-voltage amplifier low-pass filters, a
reconstructor and a controller. We investigate the impact on the closed loop bandwidth of changes in controller configuration
and certain system parameters, such as low pass filter bandwidth and camera integration and readout time. Control strategies
were tested on simple models before implementation on the full VTT model. Using the models, different control strategies are
compared. 相似文献
3.
The passivation of calcite by acid mine water. Column experiments with ferric sulfate and ferric chloride solutions at pH 2 总被引:2,自引:1,他引:1
Josep M. Soler Marco Boi Jos Luis Mogolln Jordi Cama Carlos Ayora Peter S. Nico Nobumichi Tamura Martin Kunz 《Applied Geochemistry》2008,23(12):3579-3588
Column experiments, simulating the behavior of passive treatment systems for acid mine drainage, have been performed. Acid solutions (HCl or H2SO4, pH 2), with initial concentrations of Fe(III) ranging from 250 to 1500 mg L−1, were injected into column reactors packed with calcite grains at a constant flow rate. The composition of the solutions was monitored during the experiments. At the end of the experiments (passivation of the columns), the composition and structure of the solids were measured. The dissolution of calcite in the columns caused an increase in pH and the release of Ca into the solution, leading to the precipitation of gypsum and Fe–oxyhydroxysulfates (Fe(III)–SO4–H+ solutions) or Fe–oxyhydroxychlorides (Fe(III)–Cl–H+ solutions). The columns worked as an efficient barrier for some time, increasing the pH of the circulating solutions from 2 to 6–7 and removing its metal content. However, after some time (several weeks, depending on the conditions), the columns became chemically inert. The results showed that passivation time increased with decreasing anion and metal content of the solutions. Gypsum was the phase responsible for the passivation of calcite in the experiments with Fe(III)–SO4–H+ solutions. Schwertmannite and goethite appeared as the Fe(III) secondary phases in those experiments. Akaganeite was the phase responsible for the passivation of the system in the experiments with Fe(III)–Cl–H+ solutions. 相似文献
4.
A. R. Lupo I. I. Mokhov S. Dostoglou A. R. Kunz J. P. Burkhardt 《Izvestiya Atmospheric and Oceanic Physics》2007,43(1):45-51
It was shown that abrupt changes in the large-scale structure of atmospheric flows may lead to the rapid decay of blocking. Analysis of phase diagrams made it possible to identify when sharp changes occurred in the dynamics of the system. The connection of these changes to the decay of blocking was estimated for three blocking events in the Southern Hemisphere. In addition to phase diagrams, enstrophy was used as a diagnostic tool for the analysis of blocking events. From the results of this analysis, four scenarios for the decay mechanisms were determined: (i) decay with a lack of synoptic-scale support, (ii) decay with an active role for synoptic processes, and (iii–iv) either of these mechanisms in the interaction with an abrupt change in the character of the planetary-scale flow. 相似文献
5.
6.
Methodology for construction, calibration and validation of a national hydrological model for Denmark 总被引:13,自引:0,他引:13
Hans Jrgen Henriksen Lars Troldborg Per Nyegaard Torben Obel Sonnenborg Jens Christian Refsgaard Bjarne Madsen 《Journal of Hydrology》2003,280(1-4):52-71
An integrated groundwater/surface water hydrological model with a 1 km2 grid has been constructed for Denmark covering 43,000 km2. The model is composed of a relatively simple root zone component for estimating the net precipitation, a comprehensive three-dimensional groundwater component for estimating recharge to and hydraulic heads in different geological layers, and a river component for streamflow routing and calculating stream–aquifer interaction. The model was constructed on the basis of the MIKE SHE code and by utilising comprehensive national databases on geology, soil, topography, river systems, climate and hydrology. The present paper describes the modelling process for the 7330 km2 island of Sjælland with emphasis on the problems experienced in combining the classical paradigms of groundwater modelling, such as inverse modelling of steady-state conditions, and catchment modelling, focussing on dynamic conditions and discharge simulation. Three model versions with different assumptions on input data and parameter values were required until the performance of the final, according to pre-defined accuracy criteria, model was evaluated as being satisfactory. The paper highlights the methodological issues related to establishment of performance criteria, parameterisation and assessment of parameter values from field data, calibration and validation test schemes. Most of the parameter values were assessed directly from field data, while about 10 ‘free’ parameters were subject to calibration using a combination of inverse steady-state groundwater modelling and manual trial-and-error dynamic groundwater/surface water modelling. Emphasising the importance of tests against independent data, the validation schemes included combinations of split-sample tests (another period) and proxy-basin tests (another area). 相似文献
7.
8.
Nathalie van Vliet Ole Mertz Andreas Heinimann Tobias Langanke Unai Pascual Birgit Schmook Cristina Adams Dietrich Schmidt-Vogt Peter Messerli Stephen Leisz Jean-Christophe Castella Lars Jørgensen Torben Birch-Thomsen Cornelia Hett Thilde Bech-Bruun Amy Ickowitz Kim Chi Vu Kono Yasuyuki Jefferson Fox Christine Padoch Alan D. Ziegler 《Global Environmental Change》2012,22(2):418-429
This meta-analysis of land-cover transformations of the past 10–15 years in tropical forest-agriculture frontiers world-wide shows that swidden agriculture decreases in landscapes with access to local, national and international markets that encourage cattle production and cash cropping, including biofuels. Conservation policies and practices also accelerate changes in swidden by restricting forest clearing and encouraging commercial agriculture. However, swidden remains important in many frontier areas where farmers have unequal or insecure access to investment and market opportunities, or where multi-functionality of land uses has been preserved as a strategy to adapt to current ecological, economic and political circumstances. In some areas swidden remains important simply because intensification is not a viable choice, for example when population densities and/or food market demands are low. The transformation of swidden landscapes into more intensive land uses has generally increased household incomes, but has also led to negative effects on the social and human capital of local communities to varying degrees. From an environmental perspective, the transition from swidden to other land uses often contributes to permanent deforestation, loss of biodiversity, increased weed pressure, declines in soil fertility, and accelerated soil erosion. Our prognosis is that, despite the global trend towards land use intensification, in many areas swidden will remain part of rural landscapes as the safety component of diversified systems, particularly in response to risks and uncertainties associated with more intensive land use systems. 相似文献
9.
Variability of Fram Strait sea ice export: causes, impacts and feedbacks in a coupled climate model 总被引:1,自引:2,他引:1
Analyses of a 500-year control integration of the global coupled atmosphere–sea ice–ocean model ECHAM5.0/MPI-OM show a high
variability in the ice export through Fram Strait on interannual to decadal timescales. This variability is mainly determined
by variations in the sea level pressure gradient across Fram Strait and thus geostrophic wind stress. Ice thickness anomalies,
formed at the Siberian coast and in the Chukchi Sea, propagate across the Arctic to Fram Strait and contribute to the variability
of the ice export on a timescale of about 9 years. Large anomalies of the ice export through Fram Strait cause fresh water
signals, which reach the Labrador Sea after 1–2 years and lead to significant changes in the deep convection. The associated
anomalies in ice cover and ocean heat release have a significant impact on air temperature in the Labrador Sea and on the
large-scale atmospheric circulation. This affects the sea ice transport and distribution in the Arctic again. Sensitivity
studies, simulating the effect of large ice exports through Fram Strait, show that the isolated effect of a prescribed ice/fresh
water anomaly is very important for the climate variability in the Labrador Sea. Thus, the ice export through Fram Strait
can be used for predictability of Labrador Sea climate up to 2 years in advance. 相似文献
10.
Hartmut H. Hellmer Monika Rhein Günther Heinemann Janna Abalichin Wafa Abouchami Oliver Baars Ulrich Cubasch Klaus Dethloff Lars Ebner Eberhard Fahrbach Martin Frank Gereon Gollan Richard J. Greatbatch Jens Grieger Vladimir M. Gryanik Micha Gryschka Judith Hauck Mario Hoppema Oliver Huhn Torsten Kanzow Boris P. Koch Gert König-Langlo Ulrike Langematz Gregor C. Leckebusch Christof Lüpkes Stephan Paul Annette Rinke Bjoern Rost Michiel Rutgers van der Loeff Michael Schröder Gunther Seckmeyer Torben Stichel Volker Strass Ralph Timmermann Scarlett Trimborn Uwe Ulbrich Celia Venchiarutti Ulrike Wacker Sascha Willmes Dieter Wolf-Gladrow 《Ocean Dynamics》2016,66(11):1379-1413