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181.
Elcia M.S. Brito Robert Duran Marisol Goñi-Urriza Miriam A.C. Crapez Julio C.A. Wasserman 《Marine pollution bulletin》2009,58(3):418-423
Mangroves are sensitive ecosystems of prominent ecological value that lamentably have lost much of their areas across the world. The vulnerability of mangroves grown in proximity to cities requires the development of new technologies for the remediation of acute oil spills and chronic contaminations. Studies on oil remediation are usually performed with in vitro microcosms whereas in situ experiments are rare. The aim of this work was to evaluate oil degradation on mangrove ecosystems using in situ microcosms seeded with an indigenous hydrocarbonoclastic bacterial consortium (HBC). Although the potential degradation of oil through HBC has been reported, their seeding directly on the sediment did not stimulate oil degradation during the experimental period. This is probably due to the availability of carbon sources that are easier to degrade than petroleum hydrocarbons. Our results emphasize the fragility of mangrove ecosystems during accidental oil spills and also the need for more efficient technologies for their remediation. 相似文献
182.
Joel B. Smith Kenneth M. Strzepek Julio Cardini Mario Castaneda Julie Holland Carlos Quiroz Tom M. L. Wigley Jose Herrero Peter Hearne John Furlow 《Climatic change》2011,108(3):457-470
La Ceiba, Honduras, a city of about 200,000 people, lies along the Caribbean Sea, nestled against a mountain range and the
Rio Cangrejal. The city faces three flooding risks: routine flooding of city streets due to the lack of a stormwater drainage
system; occasional major flooding of the Rio Cangrejal, which flows through the city; and flooding from heavy rainfall events
and storm surges associated with tropical cyclones. In this study, we applied a method developed for the U.S. Agency for International
Development and then worked with stakeholders in La Ceiba to understand climate change risks and evaluate adaptation alternatives.
We estimated the impacts of climate change on the current flooding risks and on efforts to mitigate the flooding problems.
The climate change scenarios, which addressed sea level rise and flooding, were based on the Intergovernmental Panel on Climate
Change estimates of sea level rise (Houghton et al. 2001) and published literature linking changes in temperature to more intense precipitation (Trenberth et al., Bull Am Meteorol
Soc, 84:1205–1217, 2003) and hurricanes (Knutson and Tuleya, J Clim, 17:3477–3495, 2004). Using information from Trenberth et al., Bull Am Meteorol Soc, 84:1205–1217, (2003) and Knutson and Tuleya, J Clim, 17:3477–3495, 2004, we scaled intense precipitation and hurricane wind speed based on projected temperature increases. We estimated the volume
of precipitation in intense events to increase by 2 to 4% in 2025 and by 6 to 14% by 2050. A 13% increase in intense precipitation,
the high scenario for 2050, could increase peak 5-year flood flows by about 60%. Building an enhanced urban drainage system
that could cope with the estimated increased flooding would cost one-third more than building a system to handle current climate
conditions, but would avoid costlier reconstruction in the future. The flow of the Rio Cangrejal would increase by one-third
from more intense hurricanes. The costs of raising levees to protect the population from increased risks from climate change
would be about $1 million. The coast west of downtown La Ceiba is the most vulnerable to sea level rise and storm surges.
It is relatively undeveloped, but is projected to have rapid development. Setbacks on coastal construction in that area may
limit risks. The downtown coastline is also at risk and may need to be protected with groins and sand pumping. Stakeholders
in La Ceiba concluded that addressing problems of urban drainage should be a top priority. They emphasized improved management
of the Rio Cangrejal watershed and improved storm warnings to cope with risks from extreme precipitation and cyclones. Adoption
of risk management principles and effective land use management could also help reduce risks from current climate and climate
change. 相似文献
183.
Mihaela I. Chidean Antonio J. Caamao Carlos Casanova-Mateo Julio Ramiro-Bargueo Sancho Salcedo-Sanz 《Theoretical and Applied Climatology》2020,140(3):927-949
The authors present a novel self-organized climate regionalization (CR) method that obtains a spatial clustering of regions, based on the explained variance of physical measurements in their coverage. This method enables a microscopic characterization of the probabilistic spatial extent of climate regions, using the statistics of the obtained clusters. It also allows for the study of the macroscopic behaviour of climate regions through time by using the dissimilarity among different cluster size probability histograms. The main advantages of the presented method, based on the Second-Order Data-Coupled Clustering (SODCC) algorithm, are that SODCC is robust to the selection of tunable parameters and that it does not require a regular or homogeneous grid to be applied. Moreover, the SODCC method has higher spatial resolution, lower computational complexity, and allows for a more direct physical interpretation of the outputs than other existing CR methods, such as Empirical Orthogonal Function (EOF) or Rotated Empirical Orthogonal Function (REOF). These facts are illustrated with an example of winter wind speed regionalization in the Iberian Peninsula through the period (1979 − 2014). This study also reveals that the North Atlantic Oscillation (NAO) has a high influence over the wind distribution in the Iberian Peninsula in a subset of years in the considered period. 相似文献
184.
We present measurements from 2006 of the marine wind speed profile at a site located 18 km from the west coast of Denmark
in the North Sea. Measurements from mast-mounted cup anemometers up to a height of 45 m are extended to 161 m using LiDAR
observations. Atmospheric turbulent flux measurements performed in 2004 with a sonic anemometer are compared to a bulk Richardson
number formulation of the atmospheric stability. This is used to classify the LiDAR/cup wind speed profiles into atmospheric
stability classes. The observations are compared to a simplified model for the wind speed profile that accounts for the effect
of the boundary-layer height. For unstable and neutral atmospheric conditions the boundary-layer height could be neglected,
whereas for stable conditions it is comparable to the measuring heights and therefore essential to include. It is interesting
to note that, although it is derived from a different physical approach, the simplified wind speed profile conforms to the
traditional expressions of the surface layer when the effect of the boundary-layer height is neglected. 相似文献
185.
We present an analysis of data from a nearly 1-year measurement campaign performed at Høvsøre, Denmark, a coastal farmland area where the terrain is flat. Within the easterly sector upstream of the site, the terrain is nearly homogenous. This topography and conditions provide a good basis for the analysis of vertical wind-speed profiles under a wide range of atmospheric stability, turbulence, and forcing conditions. One of the objectives of the campaign was to serve as a benchmark for flow over flat terrain models. The observations consist of combined wind lidar and sonic anemometer measurements at a meteorological mast. The sonic measurements cover the first 100 m and the wind lidar measures above 100 m every 50 m in the vertical. Results of the analysis of observations of the horizontal wind-speed components in the range 10–1200 m and surface turbulence fluxes are illustrated in detail, combined with forcing conditions derived from mesoscale model simulations. Ten different cases are presented. The observed wind profiles approach well the simulated gradient and geostrophic winds close to the simulated boundary-layer height during both barotropic and baroclinic conditions, respectively, except for a low-level jet case, as expected. The simulated winds are also presented for completeness and show good agreement with the measurements, generally underpredicting the turning of the wind in both barotropic and baroclinic cases. 相似文献
186.
Future climate trends for the Southwestern US, based on the climate models included in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report, project a more arid climate in the region during the 21st century. However, future climate variability associated with El Niño Southern Oscillation (ENSO)—an important driver for winter climate variability in the region—have not been addressed. In this work we evaluate future winter ENSO projections derived from two selected IPCC models, and their effect on Southwestern US climate. We first evaluate the ability of the IPCC coupled models to represent the climate of the Southwest, selecting the two models that best capture seasonal precipitation and temperature over the region and realistically represent ENSO variability (Max Planck Institute’s ECHAM5 and the UK Met Office HadCM3). Our work shows that the projected future aridity of the region will be dramatically amplified during La Niña conditions, as anomalies over a drier mean state, and will be characterized by higher temperatures (~0.5°C) and lower precipitation (~3 mm/mnt) than the projected trends. These results have important implications for water managers in the Southwest who must prepare for more intense winter aridity associated with future ENSO conditions. 相似文献
187.
Wim J. Kimmerer Nissa Ferm Mary Helen Nicolini Carolina Peñalva 《Estuaries and Coasts》2005,28(4):541-550
Egg production of planktonic copepods, is commonly measured as a proxy for secondary production in population dynamics studies
and for quantifying food limitation. Although limitation of copepod egg production by food quantity or quality is common in
natural waters, it appears less common or severe in estuaries where food concentrations are often high. San Francisco Estuary,
California, has unusually low concentrations of chlorophyll compared to other estuaries. We measured egg production rates
of three species ofAcartia, with dominate the zooplankton biomass at salinity above 15 psu, on 36 occasions during 1999–2002. Egg production was determined
by incubating up to 40 freshly collected individual copepods for 24 h in 140 ml of ambient water. Egg production was less
than 10 eggs female−1 d−1 most of the year, but as high as 52 eggs female−1 d−1 during month-long spring phytoplankton blooms. Egg production was a saturating function of total chlorophyll concentration
with a mean of 30 eggs female−1 d−1 above a chlorophyll concentration of 12±6 mg chl m−3. We take chlorophyll to be a proxy for total food ofAcartia, known to feed on microzooplankton as well as phytoplankton. These findings, together with long-term records of chlorophyll,
concentration and earlier studies of abundance of nauplius larvae in the estuary, imply chronic food limitation ofAcartia species, with sufficient food for maximum egg production <10% of the time over the last 25 yr. These results may show the
most extreme example of food limitation of copepod reproduction in any temperate estuary. They further support the idea that
estuaries may provide suitable habitat forAcartia species by virtue of other factors than high food concentration. 相似文献
188.
Soils at the hyperarid margin: The isotopic composition of soil carbonate from the Atacama Desert, Northern Chile 总被引:1,自引:0,他引:1
Jay Quade Jason A. Rech Julio L. Betancourt Mary T.K. Kalin 《Geochimica et cosmochimica acta》2007,71(15):3772-3795
We evaluate the impact of exceptionally sparse plant cover (0-20%) and rainfall (2-114 mm/yr) on the stable carbon and oxygen composition of soil carbonate along elevation transects in what is among the driest places on the planet, the Atacama Desert in northern Chile. δ13C and δ18O values of carbonates from the Atacama are the highest of any desert in the world. δ13C (VPDB) values from soil carbonate range from −8.2‰ at the wettest sites to +7.9‰ at the driest. We measured plant composition and modeled respiration rates required to form these carbonate isotopic values using a modified version of the soil diffusion model of [Cerling (1984) Earth Planet. Sci. Lett.71, 229-240], in which we assumed an exponential form of the soil CO2 production function, and relatively shallow (20-30 cm) average production depths. Overall, we find that respiration rates are the main predictor of the δ13C value of soil carbonate in the Atacama, whereas the fraction C3 to C4 biomass at individual sites has a subordinate influence. The high average δ13C value (+4.1‰) of carbonate from the driest study sites indicates it formed—perhaps abiotically—in the presence of pure atmospheric CO2.δ18O (VPDB) values from soil carbonate range from −5.9‰ at the wettest sites to +7.3‰ at the driest and show much less regular variation with elevation change than δ13C values. δ18O values for soil carbonate predicted from local temperature and δ18O values of rainfall values suggest that extreme (>80% in some cases) soil dewatering by evaporation occurs at most sites prior to carbonate formation. The effects of evaporation compromise the use of δ18O values from ancient soil carbonate to reconstruct paleoelevation in such arid settings. 相似文献
189.
190.
Katerina R. Donevska Pece V. Gorsevski Milorad Jovanovski Igor Pe?evski 《Environmental Earth Sciences》2012,67(1):121-131
This study presents a geographic information systems-based multi-criteria site selection of non-hazardous regional landfill in Polog Region, Macedonia. The multi-criteria decision framework integrates legal requirements and physical constraints that relate to environmental and economic concerns and builds a hierarchy model for landfill suitability. The methodology is used for preliminary assessment of the most suitable landfill sites by combining fuzzy set theory and analytic hierarchy process (AHP). The fuzzy set theory is used to standardize criteria using different fuzzy membership functions while the AHP is used to establish the relative importance of the criteria. The AHP makes pairwise comparisons of relative importance between hierarchy elements grouped by environmental and economic decision criteria. The landfill suitability is achieved by applying weighted linear combination that uses a comparison matrix to aggregate different importance scenarios associated with environmental and economic objectives. The results from the study suggested that a least suitable landfill area of 1.0% from the total is generated when environmental and economic objectives are valued equally while a most suitable landfill area of 1.8% area is generated when the economic objective is valued higher. Such results are aimed for enhancement of regional landfill site selection in the country that is compliant with modern EU standards. 相似文献