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1.
A novel process for a simultaneous removal of ammonia and organics was developed on the basis of ion exchange and biological reactions. From batch experiments, it was found out that NH4+ could be removed effectively by combining cation exchange and biological nitrification showing 0.98 mg N/m2?s of a maximum flux. On the other hand, the removal of NO3− was 3.5 times faster than NH4+ and the maximum flux was calculated to be 3.4 mg N/m2?s. The systems for NH4+ and NO3− removal were combined for establishing the IEBR process. When the process was operated in a continuous mode, approximately 95.8% of NH4+ was removed showing an average flux of 0.22 mg N/m2·s. The removal efficiency of total nitrogen was calculated as 94.5% whereas that of organics was 99.5%. It was concluded that the IEBR process would be effectively used for a simultaneous removal of NH4+ and organics. 相似文献
2.
Kelly M. Cobourn Hannah J. Burrack Rachael E. Goodhue Jeffrey C. Williams Frank G. Zalom 《Journal of Environmental Economics and Management》2011,62(2):278-289
A modeler must often rely on highly simplified representations of complex physical systems when analyzing associated economic issues. Herein, we consider a management problem in which a bioeconomic system exhibits simultaneity in processes governing productivity and damage. In this case, it may benefit the producer to sacrifice productivity to reduce the costs associated with increased damage. We specify empirically a structural damage relationship that explains the biological process by which an invasive species damages a host and estimate the structural model and its reduced form with an exceptional dataset on infestation of olives by the olive fruit fly. We contrast the results of these models with the approach typically taken in the economic literature, which expresses damage as a function of pest density. The population-based approach introduces significantly greater bias into the individual grower's choice of damage-control inputs than estimates based on the structural model. 相似文献
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针对零星居民点的污水处理,开发了射流曝气周期活性污泥法工艺.它是一种连续进水、周期性间歇曝气的改良型SBR工艺,也是一种时间程序和空间程序相结合的污水处理工艺,具有良好的脱氮除磷效果.试验表明,在水力负荷4 m3/d,曝气周期为每2 h曝气15 min、静置105 min的条件下,出水COD为48.8~53.5 mg/L,去除率达79.4%~80.5%;出水TN为2.81~3.98 mg/L,去除率达82.4%~89.4%;出水NH3-N为0.36~0.78 mg/L,去除率高达96.4%~98.4%;出水TP为0.63~1.18 mg/L,去除率为67.2%~78.9%,均可达到《城镇污水处理厂污染物排放标准》(GB 18918-2002)中的一级B排放标准. 相似文献
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Brooke E. Buckley Walter W. Piegorsch R. Webster West 《Environmental and Ecological Statistics》2009,16(1):53-62
In modern environmental risk analysis, inferences are often desired on those low dose levels at which a fixed benchmark risk
is achieved. In this paper, we study the use of confidence limits on parameters from a simple one-stage model of risk historically
popular in benchmark analysis with quantal data. Based on these confidence bounds, we present methods for deriving upper confidence
limits on extra risk and lower bounds on the benchmark dose. The methods are seen to extend automatically to the case where
simultaneous inferences are desired at multiple doses. Monte Carlo evaluations explore characteristics of the parameter estimates
and the confidence limits under this setting.
相似文献
R. Webster WestEmail: |
7.
R. Webster West Daniela K. Nitcheva Walter W. Piegorsch 《Environmental and Ecological Statistics》2009,16(1):63-73
A primary objective in quantitative risk assessment is the characterization of risk which is defined to be the likelihood
of an adverse effect caused by an environmental toxin or chemcial agent. In modern risk-benchmark analysis, attention centers
on the “benchmark dose” at which a fixed benchmark level of risk is achieved, with a lower confidence limits on this dose
being of primary interest. In practice, a range of benchmark risks may be under study, so that the individual lower confidence
limits on benchmark dose must be corrected for simultaneity in order to maintain a specified overall level of confidence.
For the case of quantal data, simultaneous methods have been constructed that appeal to the large sample normality of parameter
estimates. The suitability of these methods for use with small sample sizes will be considered. A new bootstrap technique
is proposed as an alternative to the large sample methodology. This technique is evaluated via a simulation study and examples
from environmental toxicology.
相似文献
R. Webster WestEmail: |
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黄河北干流与渭河相遇洪水分析 总被引:2,自引:0,他引:2
黄河北干流与渭河位于黄土高原,暴雨是洪水的重要成因.本文分析了近2000年的历史资料,提出该地区的洪水具有周期性,19世纪洪水达到高峰,20世纪洪水规模有所降低,并分析了黄河北干流与渭河及其支流径、洛河洪水相遇问题:四河相遇的概率很小,多形成特大洪水,两河相遇是较常发生的事件,多形成中等以下洪水。三门峡水库的淤积使该地区洪水灾害加剧.同时还分析了该地区洪水对黄河下游洪水的影响。 相似文献
10.
Jing Li Haiqin Yu Xue Zhang Rixin Zhu Liangguo Yan 《Frontiers of Environmental Science & Engineering》2020,14(3):52