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821.
Brack W Klamer HJ López de Alda M Barceló D 《Environmental science and pollution research international》2007,14(1):30-38
Background, Aim and Scope
Extensive monitoring programs on chemical contamination are run in many European river basins. With respect to the implementation
of the European Union (EU) Water Framework Directive (WFD), these programs are increasingly accompanied by monitoring the
ecological status of the river basins. Assuming an impact of chemical contamination on the ecological status, the assignment
of effects in aquatic ecosystems to those stressors that cause the effects is a prerequisite for taking political or technical
measures to achieve the goals of the WFD. Thus, one focus of present European research is on toxicant identification in European
river basins in order to allow for a reduction of toxic pressure on aquatic ecosystems according to the WFD.
Main Features:
An overview is presented on studies that were performed to link chemical pollution in European river basins to measurable
ecotoxic effects. This includes correlation-based approaches as well as investigations that apply effect-directed analysis
(EDA) integrating toxicity testing, fractionation and non-target chemical analysis. Effect-based key toxicants that were identified
in European surface waters are compiled and compared to EU priority pollutants. Further needs for research are identified.
Results:
Studies on the identification of effect-based key toxicants focused on mutagenicity, aryl hydrocarbon receptor-mediated effects,
endocrine disruption, green algae, and invertebrates. The identified pollutants include priority pollutants and other well-known
environmental pollutants such as polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins, furans, and biphenyls,
nonylphenol, some pesticides and tributyltin, but also other compounds that were neither considered as environmental pollutants
before nor regulated such as substituted phenols, natural or synthetic estrogens and androgens, dinaphthofurans, 2-(2-naphthalenyl)benzothiophene,
and N-phenyl-2-naphthylamine.
Discussion:
Individual studies at specific sites in a European river basin demonstrated the power of combined biological and chemical
analytical approaches and, particularly, of effect-directed analysis. However, the available information on effect-based key
toxicants is very limited with respect to the entirety of rivers possibly at risk due to chemical contamination and with respect
to toxicological endpoints considered at a specific site. A relatively broad basis of information exists only for estrogenicity
and aryl hydrocarbon, receptor-mediated effects.
Conclusions:
The development of tools and strategies for an identification of key toxicants on a broader scale are a challenging task for
the next years. Since investigations dealing with toxicant identification are too labor and cost-intensive for monitoring
purposes, they have to be focused on the key sites in a river basin. These should include hot spots of contamination, particularly
if there is evidence that they might pose a risk for downstream areas, but may also involve accumulation zones in the lower
reach of a river in order to get an integrated picture on the contamination of the basin.
Perspectives:
While EDA is almost exclusively based on measurable effects in in vitro and in vivo biotests to date, an increasing focus
in the future should be on the integration of EDA into Ecological Risk Assessment and on the development of tools to confirm
EDA-determined key toxicants as stressors in populations, communities and ecosystems. Considering these requirements and applied
in a focused way, toxicant identification may significantly help to implement the Water Framework Directive by providing evidence
on the main stressors and possible mitigation measures in order to improve the ecological status of a river ecosystem. 相似文献
822.
Exploratory study of suspended sediment concentrations downstream of harvested peat bogs 总被引:1,自引:0,他引:1
Pavey B Saint-Hilaire A Courtenay S Ouarda T Bobée B 《Environmental monitoring and assessment》2007,135(1-3):369-382
Peat bog harvesting is an important industry in many countries, including Canada. To harvest peat, bogs are drained and drainage
water is evacuated towards neighboring rivers, estuaries or coastal waters. High suspended sediment concentrations (SSC) were
found in the drainage water at one particular site during the 2001–2002 spring seasons in New Brunswick (Canada). The main
objective of this study was to verify this observation at other sites, compare SSC levels leaving harvested peat bogs with
those leaving an unharvested bog, and to determine if high SSC events happen only in Spring or all year round. Suspended sediment
concentrations were monitored downstream of three harvested peat bogs and an unharvested reference bog located in New Brunswick
during the ice free seasons of 2003–2004. On average, SSC at the harvested sites exceeded 25 mg/l, which is the recommended
daily maximum concentration, 72% of the time, while the same concentration was exceeded 30% of the time at the unharvested
sites. SSC were found to be significantly higher at harvested sites than at the reference sites for all seasons. The highest
SSC medians were recorded in the Fall but SSC was elevated in all seasons. High SSC levels in receiving waters may be caused
by field ditching activities and insufficient sediment controls. Findings suggest the NB Peat Harvesting 25 mg/l SSC guideline
should be reviewed. 相似文献
823.
浙江某农场土壤和沟渠沉积物对氨氮的吸附研究 总被引:13,自引:1,他引:12
通过静态吸附实验,研究农田土壤及沟渠沉积物对氨氮的吸附作用.实验表明,水相氨氮浓度为5~100 mg/L时,风干农田土壤、风干沟渠沉积物及新鲜沟渠沉积物3种吸附剂的吸附等温线均呈良好线性关系,并符合Freundlich吸附模式;农田土壤与沟渠沉积物的氨氮背景含量分别为12 mg·kg-1和92 mg·kg-1,并且农田土壤对氨氮的吸附系数为8.21,而风干沟渠沉积物与新鲜沟渠沉积物吸附系数分别为5.42与6.84,因此,土壤的吸附能力要大于沟渠沉积物,后两者的吸附能力相近.对3种吸附剂吸附机制的讨论表明,吸附特性与界面性质相关,实验氨氮浓度范围内吸附作用主要为离子交换.相同实验条件下,当初始氨氮浓度较大时,随温度升高,3种吸附剂对氨氮的平衡吸附量减小,对氨氮的吸附为弱放热过程. 相似文献
824.
825.
不同河流水体颗粒物对硝化过程的影响 总被引:1,自引:0,他引:1
采用模拟实验的方法对比研究了长江和黄河水体颗粒物对硝化过程的影响.结果表明:(1)当颗粒物含量分别为0g·l-1和2g·l-1时,长江水样的平均硝化速率在前10d分别为0.21mg·l-1·d-1和0.70mg·l-1·d-1,黄河水样分别为0.18mg·l-1·d-1和0.32mg·l-1·d-1.采用Logistic模型对氨氮的硝化作用进行拟合发现,颗粒物含量为2 g·l-1时的硝化速率常数均显著高于无颗粒物存在时的硝化速率常数,说明有颗粒物存在时的硝化过程较快.(2)有颗粒物存在时,水体氨化细菌、亚硝化细菌和硝化细菌的数量均显著高于无颗粒物存在的水体,而且长江水样中各种菌的数量明显高于黄河水样.(3)长江水样中氨氮的平均硝化速率和硝化速率常数明显大于黄河,这是由于长江水样较高的细菌浓度水平和两条河流颗粒物不同的理化性质所导致. 相似文献
826.
硝基苯能够被零价铁还原成为苯胺. 利用气相色谱分析方法,研究了泥浆体系中零价铁表面积对硝基苯污染底质降解行为的影响. 结果表明,在沉积物中初始w(硝基苯)为8.87 μg/g,按照3.27 g/L最佳比例投加还原铁粉,经2 h反应约有97%的硝基苯被降解;其还原机理为表面接触反应,铁粉总表面积是影响硝基苯降解的主要参数;沉积物中硝基苯降解速率常数(K)和残留量(y)与单位体积泥浆中零价铁总表面积(ρa)之间表现为线性和负指数相关性,其关系式分别为:K0.006 5+5.165 87×10-4ρa和y8.57exp(-ρa/7.66)+0.25;零价铁还原硝基苯的降解过程,其降解动力学符合准一级方程,并且通过SEM扫描电镜发现零价铁在反应过程中表面被严重腐蚀,颗粒组成发生明显改变. 相似文献
827.
828.
重污染感潮河道底泥释放特征及其控制技术研究 总被引:11,自引:1,他引:10
以珠江三角洲城市重污染感潮河道为对象,研究了底泥污染物(重金属、有机物和营养盐)在静态、潮汐作用影响及人工曝气扰动下的释放特征.在此基础上,采用曝气充氧、重金属化学固定、激活底泥土著微生物等联合技术对底泥释放进行控制,研究其控制效果.结果表明:①感潮作用加速了底泥污染物的释放,与静态释放相比,Cu、Zn、Pb、Cr、COD、NH 4-N和TP的平均释放速率提高了1~4倍,释放量增加了0.3~1.8倍;底泥平均耗氧速率提高了1.28倍.②人工曝气扰动使底泥污染物局部急剧释放,并使泥水界面由弱碱性变成弱酸性;在有氧环境,NH 4-N、TP的释放得到有效抑制.③投加石灰调节pH至8~9,上覆水体Cu、Zn、Pb、Cr的去除率达到85%~98%,同时还可去除92%的TP和86%的浊度;在微碱性好氧条件下,Cu、Zn、Pb和Cr的释放量稳定在300μg·L-1以下.④底泥土著微生物层对水体及底泥污染物有良好的降解作用,通过间歇曝气COD、NH 4-N、TP去除率分别可达到85%、92%和71%;但微生物层具有较高的耗氧速率,达到45g·m-2·d-1. 相似文献
829.
水体沉积物中有效砷的测试新方法研究 总被引:2,自引:1,他引:1
一种氧化铁/醋酸纤维素复合膜(FeO/CAM)被用于太湖沉积物中砷的生物有效性评估.结果发现,在水介质中,FeO/CAM对沉积物中砷的富集量随土水比增加而呈乘幂函数减少,在土水质量比为0.025(即1:40)之后趋于某一平台值;在土水比为0.025并得到充分振荡的条件下,沉积物中释放的有效砷被FeO/CAM富集至膜中,并随时间增加而增加,至24 h后逐渐趋于平衡,这一过程恰当地模拟了生物对砷的吸收.因此,FeO/CAM可以用于有效砷的体外测试.利用FeO/CAM对12个总砷含量为6.4~34.6 mg·kg-1的太湖沉积物样品中的有效砷进行了测定.结果发现,FeO/CAM提取的有效砷含量与磷酸盐缓冲液提取的有效砷含量之间显著相关.太湖沉积物中的有效砷含量与总砷、总磷、有机质和吸附磷含量以及磷吸附饱和度显著相关,说明沉积物理化属性对有效砷含量有重要影响.FeO/CAM克服了化学试剂提取过程中引起的非有效态砷释放的根本缺陷,因此,FeO/CAM方法在沉积物有效砷含量的测定时比化学试剂提取法可能更准确. 相似文献
830.
R. Peter Richards 《Journal of the American Water Resources Association》1989,25(4):891-904
ABSTRACT: Evaluation of the non-point source pollutant load entering a lake from multiple tributaries requires either that all tributaries be monitored or that some extrapolation method be used to estimate loads originating in areas not monitored. Unmonitored areas include not only watersheds of tributaries that are not monitored, but also portions of a monitored tributary's drainage basin downstream from the monitoring site and areas of direct drainage. Significant portions of large lake drainage basins are often not monitored, and loads for these areas are often estimated by extrapolation. Six simple extrapolation procedures were evaluated by using them to estimate loads for areas that had been monitored and comparing the estimated loads with the monitored loads. Three approaches were based on inter-basin ratios of area, C-factor, and discharge. The other approaches used regression relationships between concentration and flow to estimate concentrations for the unmonitored basin. The ratio approaches generally were more reliable than the regression approaches. However, extrapolation by any method tested was not very precise. Some methods also were biased when applied to watersheds of a size different than the monitored one. Extrapolation by any of these methods would compromise the precision of the lake-wide load estimate, if the unmonitored area were a significant part of the entire basin. 相似文献