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41.
Virginie Guemas Francisco J. Doblas-Reyes Kristian Mogensen Sarah Keeley Yongming Tang 《Climate Dynamics》2014,43(9-10):2813-2829
Polar climate studies are severely hampered by the sparseness of the sea ice observations. We aim at filling this critical gap by producing two 5-member sea ice historical simulations strongly constrained by ocean and atmosphere observational data and covering the 1958–2006 and 1979–2012 periods. This is the first multi-member sea ice reconstruction covering more than 50 years. The obtained sea ice conditions are in reasonable agreement with the few available observations. These best estimates of sea ice conditions serve subsequently as initial sea ice conditions for a set of 28 3-year-long retrospective climate predictions. We compare it to a set in which the sea ice initial conditions are taken from a single-member sea ice historical simulation constrained by atmosphere observations only. We find an improved skill in predicting the Arctic sea ice area and Arctic near surface temperature but a slightly degraded skill in predicting the Antarctic sea ice area. We also obtain a larger spread between the members for the sea ice variables, thus more representative of the forecast error. 相似文献
42.
Kristian McConville Claudia Halsband Elaine S. Fileman Paul J. Somerfield Helen S. Findlay John I. Spicer 《Marine pollution bulletin》2013
Some planktonic groups suffer negative effects from ocean acidification (OA), although copepods might be less sensitive. We investigated the effect of predicted CO2 levels (range 480–750 ppm), on egg production and hatching success of two copepod species, Centropages typicus and Temora longicornis. In these short-term incubations there was no significant effect of high CO2 on these parameters. Additionally a very high CO2 treatment, (CO2 = 9830 ppm), representative of carbon capture and storage scenarios, resulted in a reduction of egg production rate and hatching success of C. typicus, but not T. longicornis. In conclusion, reproduction of C. typicus was more sensitive to acute elevated seawater CO2 than that of T. longicornis, but neither species was affected by exposure to CO2 levels predicted for the year 2100. The duration and seasonal timing of exposures to high pCO2, however, might have a significant effect on the reproduction success of calanoid copepods. 相似文献
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44.
Karl Thomas Hjelmervik Jan Kristian Jensen Petter ?stenstad Atle Ommundsen 《Ocean Dynamics》2012,62(2):253-264
Sonar performance modeling is crucial for submarine and anti–submarine operations. The validity of sonar performance models
is generally limited by environmental uncertainty, and particularly uncertainty in the vertical sound speed profile (SSP).
Rapid environmental assessment (REA) products, such as oceanographic surveys and ocean models may be used to reduce this uncertainty
prior to sonar operations. Empirical orthogonal functions (EOF) applied on the SSPs inherently take into account the vertical
gradients and therefore the acoustic properties. We present a method that employs EOFs and a grouping algorithm to divide
a large group of SSPs from an ocean model simulation into smaller groups with similar SSP characteristics. Such groups are
henceforth called acoustically stable groups. Each group represents a subset in space and time within the ocean model domain.
Regions with low acoustic variability contain large and geographically contiguous acoustically stable groups. In contrast,
small or fragmented acoustically stable groups are found in regions with high acoustic variability. The main output is a map
of the group distribution. This is a REA product in itself, but the map may also be used as a planning aid for REA survey
missions. 相似文献
45.
46.
Christian Azar Kristian Lindgren Michael Obersteiner Keywan Riahi Detlef P. van Vuuren K. Michel G. J. den Elzen Kenneth M?llersten Eric D. Larson 《Climatic change》2010,100(1):195-202
The United Nations Framework Convention on Climate Change (UNFCCC 1992) calls for stabilization of atmospheric greenhouse gas (GHG) concentrations at a level that would prevent dangerous anthropogenic
interference with the climate system. We use three global energy system models to investigate the technological and economic
attainability of meeting CO2 concentration targets below current levels. Our scenario studies reveal that while energy portfolios from a broad range of
energy technologies are needed to attain low concentrations, negative emission technologies—e.g., biomass energy with carbon
capture and storage (BECCS)—significantly enhances the possibility to meet low concentration targets (at around 350 ppm CO2). 相似文献
47.
Climate change impacts on water management and irrigated agriculture in the Yakima River Basin, Washington, USA 总被引:1,自引:0,他引:1
Julie A. Vano Michael J. Scott Nathalie Voisin Claudio O. Stöckle Alan F. Hamlet Kristian E. B. Mickelson Marketa McGuire Elsner Dennis P. Lettenmaier 《Climatic change》2010,102(1-2):287-317
The Yakima River Reservoir system supplies water to ~180,000 irrigated hectares through the operation of five reservoirs with cumulative storage of ~30% mean annual river flow. Runoff is derived mostly from winter precipitation in the Cascade Mountains, much of which is stored as snowpack. Climate change is expected to result in earlier snowmelt runoff and reduced summer flows. Effects of these changes on irrigated agriculture were simulated using a reservoir system model coupled to a hydrological model driven by downscaled scenarios from 20 climate models archived by the 2007 Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report. We find earlier snowmelt results in increased water delivery curtailments. Historically, the basin experienced substantial water shortages in 14% of years. Without adaptations, for IPCC A1B global emission scenarios, water shortages increase to 27% (13% to 49% range) in the 2020s, to 33% in the 2040s, and 68% in the 2080s. For IPCC B1 emissions scenarios, shortages occur in 24% (7% to 54%) of years in the 2020s, 31% in the 2040s and 43% in the 2080s. Historically unprecedented conditions where senior water rights holders suffer shortfalls occur with increasing frequency in both A1B and B1 scenarios. Economic losses include expected annual production declines of 5%–16%, with greater probabilities of operating losses for junior water rights holders. 相似文献
48.
Coarse-scale data assimilation (DA) with large ensemble size is proposed as a robust alternative to standard DA with localization for reservoir history matching problems. With coarse-scale DA, the unknown property function associated with each ensemble member is upscaled to a grid significantly coarser than the original reservoir simulator grid. The grid coarsening is automatic, ensemble-specific and non-uniform. The selection of regions where the grid can be coarsened without introducing too large modelling errors is performed using a second-generation wavelet transform allowing for seamless handling of non-dyadic grids and inactive grid cells. An inexpensive local-local upscaling is performed on each ensemble member. A DA algorithm that restarts from initial time is utilized, which avoids the need for downscaling. Since the DA computational cost roughly equals the number of ensemble members times the cost of a single forward simulation, coarse-scale DA allows for a significant increase in the number of ensemble members at the same computational cost as standard DA with localization. Fixing the computational cost for both approaches, the quality of coarse-scale DA is compared to that of standard DA with localization (using state-of-the-art localization techniques) on examples spanning a large degree of variability. It is found that coarse-scale DA is more robust with respect to variation in example type than each of the localization techniques considered with standard DA. Although the paper is concerned with two spatial dimensions, coarse-scale DA is easily extendible to three spatial dimensions, where it is expected that its advantage with respect to standard DA with localization will increase. 相似文献
49.
50.
The on-going process of setting up a national system for identification, approval and implementation of CDM-projects in China illustrates the changes in the Chinese attitude towards the CDM after COP7. This is a very important process, and the outcome could strongly influence investors’ willingness to invest in Chinese CDM-projects. The massive interest and capacity building by international assistance organisations, bilateral and multilateral donors, for preparing the implementation of the CDM will provide China with information and experience. Nevertheless, potential factors that may negatively influence efficient implementation of CDM-projects are: the domestic implementation system is not yet finalised and may impact on China’s ability to compete for CDM-projects; the priorities of the Chinese authorities may not match those of foreign investors; the main expertise regarding CDM is found in a few ministries and research institutes in Beijing, and there is a need to increase capacity for CDM among local project developers and authorities; most research carried out concerned technical issues, and there is a need to include economists and market experts in order to increase understanding of the market. 相似文献