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991.
A. Allen Bradley Forrest M. Holly William K. Walker Scott A. Wright 《Journal of the American Water Resources Association》1998,34(3):467-480
ABSTRACT: A continuous simulation approach is proposed for estimating water temperature exceedance probabilities using thermo-hydrodynamic modeling. The approach uses (1) a deterministic unsteady flow and heat transport model, (2) continuous hydrological and meteorological data for a long historical period, and (3) synthetic records of tributary water temperatures and other model inputs. Representative historical records of streamflow, air temperatures, and other hydrometeorological variables are obtained from nearby gages. Stochastic modeling methods are used to construct synthetic records for other model inputs, including inflow water temperatures. An application of this deterministic-stochastic approach is presented for a complex waterway in northeastern Illinois with heat discharges from several power plants and wastewater treatment plants. Statistical results from the continuous simulations are compared to results obtained from traditional event simulations. The application illustrates the information that engineers and biologists can obtain for (1) evaluating compliance with water temperature standards, and (2) assessing the effect of water temperatures on aquatic habitat. 相似文献
992.
993.
水产品加工废水生物处理现状与展望 总被引:1,自引:0,他引:1
介绍了几种较为典型的水产品加工废水生物处理工艺,以及利用生物处理工艺处理高含盐量废水实验室研究结果;展望了水产品加工废水处理技术的发展前景。 相似文献
994.
995.
对水解(酸化)反应器处理水产品加工废水进行了试验研究,研究结果表明,在水温为20℃左右、进水COD为1100mg/L左右、水力停留时间大于2h的条件下,无需曝气作用,水解(酸化)反应器对水产品加工废水中COD的去除率大于40%。水产品加工废水具有较好的可生化性,水解(酸化)反应器对该废水可生化性能的改善作用不明显。利用Eckenfelder生物滤池数学模式对水解(酸化)反应器进行了分析,得到了水解(酸化)反应器处理水产品加工废水的生物处理动力学方程:Sc/SD=e^-0.23D/L^0.24。 相似文献
996.
基于ARIMA模型的区域水生态足迹时间序列分析 总被引:20,自引:2,他引:20
20世纪末以来,生态足迹理论应用研究成为生态经济学的一个热点,而生态足迹指标的可预测性一直是研究中争论的一个焦点。通过分析1949—1998年广州市的水生态足迹变化,并对计算结果进行ARIMA模型时间序列预测分析,以揭示广州水资源利用和水产品消耗的发展变化规律,并根据其发展变化规律预测广州市未来水生态足迹的变动。结果表明,ARIMA(2,2,2)模型能较好的拟合广州市1949—1993年期间水生态足迹变化,经1994—1998年实际计算结果验证所建模型,误差在5%左右;应用ARIMA(2,2,2)预测广州市1999—2008年的人均水生态足迹,结果分别为:0.5935,0.656 2,0.714 7,0.779 0,0.840 2,0.901 55,0.964 11,1.025 57,1.087 44,1.149 43 hm2,预测结果表明广州市1999—2008年期间的人均水生态足迹仍呈较快上升趋势,居民对于水产品的需求提高以及城市发展、人口增加等社会经济因素是导致这种趋势产生的主要原因。 相似文献
997.
CarbondioxidereleaseduetochangeinlanduseinChinamainlandWangXiaoke;ZhuangYahui;FengZongwei(ResearchCenterforEco-EnvironmentalS... 相似文献
998.
Xinxian Zhang A. David McGuire Roger W. Ruess 《Mitigation and Adaptation Strategies for Global Change》2006,11(1):147-171
A major challenge confronting the scientific community is to understand both patterns of and controls over spatial and temporal
variability of carbon exchange between boreal forest ecosystems and the atmosphere. An understanding of the sources of variability
of carbon processes at fine scales and how these contribute to uncertainties in estimating carbon fluxes is relevant to representing
these processes at coarse scales. To explore some of the challenges and uncertainties in estimating carbon fluxes at fine
to coarse scales, we conducted a modeling analysis of canopy foliar maintenance respiration for black spruce ecosystems of
Alaska by scaling empirical hourly models of foliar maintenance respiration (Rm) to estimate canopy foliar Rm for individual stands. We used variation in foliar N concentration among stands to develop hourly stand-specific models and
then developed an hourly pooled model. An uncertainty analysis identified that the most important parameter affecting estimates
of canopy foliar Rm was one that describes Rm at 0 ∘C per g N, which explained more than 55% of variance in annual estimates of canopy foliar Rm. The comparison of simulated annual canopy foliar Rm identified significant differences between stand-specific and pooled models for each stand. This result indicates that control
over foliar N concentration should be considered in models that estimate canopy foliar Rm of black spruce stands across the landscape. In this study, we also temporally scaled the hourly stand-level models to estimate
canopy foliar Rm of black spruce stands using mean monthly temperature data. Comparisons of monthly Rm between the hourly and monthly versions of the models indicated that there was very little difference between the estimates
of hourly and monthly models, suggesting that hourly models can be aggregated to use monthly input data with little loss of
precision. We conclude that uncertainties in the use of a coarse-scale model for estimating canopy foliar Rm at regional scales depend on uncertainties in representing needle-level respiration and on uncertainties in representing
the spatial variability of canopy foliar N across a region. The development of spatial data sets of canopy foliar N represents
a major challenge in estimating canopy foliar maintenance respiration at regional scales. 相似文献
999.
城市发展与城市生态系统评价 总被引:3,自引:0,他引:3
陈尧华 《城市环境与城市生态》1994,7(3):27-30
本文从解决城市环境问题出发,根据城市发展与环境污染相互联系,指出了必须改变目前的单个建设项目评价方式,提出了对城市生态系统进行评价的观点,并对城市生态系统评价所涉及的若干问题做了初步探讨分析。 相似文献
1000.
We developed a time dynamic model to investigate the temporal dynamics of nematode community in the brackish zone of the Westerschelde Estuary. The biomass of four nematode feeding groups observed from March 1991 to February 1992 is used to calibrate the model. Using environmental data as the input, the model predicts the temporal modification and interrelation of four nematode feeding groups. Nematodes achieve a dominant position in the community because of their lower loss rate (in respiration, excretion and natural death). Predators which are deposit-feeding macrobenthos control the variations of dominant nematodes, such as omnivores and non-selective deposit feeders. Food availability causes modification only for rare nematodes such as epigrowth feeders and selective deposit feeders. Temperature is a factor affecting both predation death and a loss including respiration, excretion and natural death. Overall, the modification of nematode community by food availability is much lower than by predator. The macrobenthos in the Westerschelde Estuary decrease from upstream to the estuarine mouth. The stability and standing stock of nematode population follow the opposite gradient of their predators. They increase from upstream to the estuarine mouth. 相似文献