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111.
This study compared three forecasting models based on the mean absolute percentage errors (MAPE) of their accuracy in forecasting
air pollution in a traffic tunnel: the Grey model (GM), the combination model used four sample point and five sample point
prediction with GM (1,1)(GM(1,1)4 + 5), and the modified grey model (MGM). An MGM was combined using the four points of the original sequence using the original
grey prediction GM (1,1) for short-term forecasting. The proposed method cannot only enhance the prediction accuracy of the
original grey model, but can also solve the jump data forecasting problem something for which the original grey model is inappropriate.
The MAPE was applied to the models, and the MGM found the proposed method to be simple and efficient. The MAPE of MGM, calculated
over 3 h of forecasts, were as follows: 10.12 (Upwind), 10.07 (Middle) and 7.68 (Downwind) for CO; 10.79 (Upwind), 6.05 (Middle)
and 5.98 (Downwind) for NO
x
, and 11.67 (Upwind), 7.32 (Middle) and 4.56 (Downwind) for NMHC. The MGM model results reveal that the combined forecasts
can significantly decrease the overall forecasting error. Results of this demonstrate that MGM can accurately forecast air
pollution in the Kaohsiung Chung–Cheng Tunnel. 相似文献
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An Aquifer Vulnerability Assessment of the Paluxy Aquifer, Central Texas, USA, Using GIS and a Modified DRASTIC Approach 总被引:9,自引:1,他引:8
D epth to water, net Recharge, Aquifer media, Soil media,
Topography, Impact of the vadose zone, and
Conductivity of the aquifer). Using such an approach allows one to investigate the potential for groundwater contamination
on a regional, rather than site-specific, scale. Based upon data from variables such as soil permeability, depth to water,
aquifer hydraulic conductivity, and topography, subjective numerical weightings have been assigned according to the variable's
relative importance in regional groundwater quality. The weights for each variable comprise a GIS map layer. These map layers
are combined to formulate the final groundwater pollution potential map. Using this method of investigation, the pollution
potential map for the study area classifies 47% of the area as having low pollution potential, 26% as having moderate pollution
potential, 22% as having high pollution potential, and 5% as having very high pollution potential. 相似文献
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Forecasting relative impacts of land use on anadromous fish habitat to guide conservation planning. 总被引:1,自引:0,他引:1
Kathleen A Lohse David A Newburn Jeff J Opperman Adina M Merenlender 《Ecological applications》2008,18(2):467-482
Land use change can adversely affect water quality and freshwater ecosystems, yet our ability to predict how systems will respond to different land uses, particularly rural-residential development, is limited by data availability and our understanding of biophysical thresholds. In this study, we use spatially explicit parcel-level data to examine the influence of land use (including urban, rural-residential, and vineyard) on salmon spawning substrate quality in tributaries of the Russian River in California. We develop a land use change model to forecast the probability of losses in high-quality spawning habitat and recommend priority areas for incentive-based land conservation efforts. Ordinal logistic regression results indicate that all three land use types were negatively associated with spawning substrate quality, with urban development having the largest marginal impact. For two reasons, however, forecasted rural-residential and vineyard development have much larger influences on decreasing spawning substrate quality relative to urban development. First, the land use change model estimates 10 times greater land use conversion to both rural-residential and vineyard compared to urban. Second, forecasted urban development is concentrated in the most developed watersheds, which already have poor spawning substrate quality, such that the marginal response to future urban development is less significant. To meet the goals of protecting salmonid spawning habitat and optimizing investments in salmon recovery, we suggest investing in watersheds where future rural-residential development and vineyards threaten high-quality fish habitat, rather than the most developed watersheds, where land values are higher. 相似文献
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