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焦化厂土壤中多环芳烃分布特征及淋洗粒级分割点确定 总被引:5,自引:1,他引:5
土壤粒径分布和污染物在不同粒级土壤中的分布特征是污染土壤淋洗可处理性的重要依据,淋洗粒级分割点则是淋洗工艺的重要参数.根据土壤异位淋洗的技术要求,在焦化厂污染场地进行了采样,测定了土样的粒径分布曲线及不同粒级土壤中美国EPA优控的16种多环芳烃(PAHs)的初始浓度,并采用Tween 80和Triton X-100溶液对不同粒级污染土样进行了振荡清洗实验.结果表明,16种PAHs在6个粒级中的总浓度在6.27~40.18 mg/kg范围,呈双峰分布模式,单个PAH污染物的最高浓度大多出现在250~500 μm的颗粒中, 50~75 μm的颗粒中污染物浓度最低;PAHs去除率与其初始浓度及土壤特性有关,初始浓度越低,去除率越高,粗颗粒中由于有机碳含量较高,PAHs去除效率反而低于细颗粒.根据清洗效果并从废物减量化角度出发,确定以50 μm作为土壤淋洗的粒级分割点,这样减容率可以达到82.95%. 相似文献
146.
采集某焦化厂废水处理系统的数据,选取当前常用的3种焦化废水处理技术和该焦化厂现用废水处理技术建立了较为完整的模糊综合评价数学模型,选择技术综合评价的评价因素集,利用判断矩阵分析法确定各评价因素的权重,建立了各定量因素指标的隶属函数,确定了各定性因素指标的模糊评语集,最后以模糊矩阵的合成运算完成模糊综合评价.4种焦化废水处理技术的综合性能优劣次序为:该焦化厂现用废水处理技术>普通活性污泥法>湿式催化氧化法>多相光催化氧化法. 相似文献
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采用内电解—Fenton氧化—絮凝沉淀的化学集成技术预处理焦化废水,优化了各工段的运行参数。实验结果表明:在钢铁铁屑与活性炭的体积比为1∶1的条件下,内电解工段的优化参数为进水pH 2.6~3.1、HRT=1.0 h;Fenton氧化工段的优化参数为Fe2+加入量200 mg/L、H2O2加入量1 000 mg/L、进水pH 3.0左右、反应时间1.0 h;絮凝沉淀工段的设定参数为进水pH 9.5~10.0、聚丙烯酰胺加入量1 mg/L、静置沉降0.5 h。在上述工艺条件下,该集成技术对废水的总COD去除率大于55%,处理后的废水BOD5/COD大于0.28,不添加稀释新水即可进入后续生化处理系统。该工艺占地面积小、系统结构简单、易于工业化,废水预处理成本为4~5元/t。 相似文献
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Mercury concentrations are usually significant in historic Hg mining districts all over the world, so the atmospheric environment is potentially affected. In Asturias, northern Spain, past mining operations have left a legacy of ruins and Hg-rich wastes, soils and sediments in abandoned sites. Total Hg concentrations in the ambient air of these abandoned mine sites have been investigated to evaluate the impact of the Hg emissions. This paper presents the synthesis of current knowledge about atmospheric Hg contents in the area of the abandoned Hg mining and smelting works at ‘La Peña–El Terronal’ and La Soterraña, located in Mieres and Pola de Lena districts, respectively, both within the Caudal River basin. It was found that average atmospheric Hg concentrations are higher than the background level in the area (0.1 μg Nm?3), reaching up to 203.7 μg Nm?3 at 0.2 m above the ground level, close to the old smelting chimney at El Terronal mine site. Data suggest that past Hg mining activities have big influences on the increased Hg concentrations around abandoned sites and that atmospheric transfer is a major pathway for Hg cycling in these environments. 相似文献
150.
Lu LT Chang IC Hsiao TY Yu YH Ma HW 《Environmental science and pollution research international》2007,14(1):49-59
Background Since the 1970s, at least 200 hectares (ha) of farmland has been polluted by the heavy metal cadmium (Cd).Consequently, the
Cd pollution has led to contaminate the rice production and caused acute social panic. According to the recent investigation
results performed by the Taiwan Environmental Protection Administration (TEPA), it is indicated that most of the Cd pollution
incidents in Taiwan resulted from the wastewater discharge of stearate Cd factories. To prevent the Cd pollution incidents
from spreading, the TEPA has either forced these factories to close down or assisted them in improving their production processes
since the 1980s. Unfortunately, accidental incidents of Cd pollution still emerge in an endless stream, despite the strict
governmental controls placed on these questionable factories. Whether this pollution has resulted from undetected or hidden
pollution sources stemming from two decades ago or comes from some new source, will be an outstanding issue. Therefore, this
study attempts to identify the pollution sources of Cd in soil in Taiwan as well as to find the solution to the above-mentioned,
outstanding issue by way of a methodology termed Material Flow Analysis (MFA).
Method logy. The MFA has proved to be a useful tool on providing quantitative information of the flow of substances through an economic
to an environmental system. Based upon the supply-and-demand theory of MFA, researchers have successfully conducted an overview
of the use of materials in many industries, the construction industry being one of these. Therefore, this study tries to establish
a set of analytical processes by way of MFA for identifying the pollution source of Cd in soil in Taiwan. In addition, the
spirit of Life Cycle Analysis (LCA) technique was also employed to identify the materials, and products should be ignored
as a crucial pollution source in this study.
Results and Discussion According to the MFA methodology applied in this study and on the basis of related studies performed by Taiwanese governmental
authorities, we arrive at the following analysis results: (1) the total amount of Cd from the economic perspective of material
and product flow was approximately 441.2 tons; (2) the wastewater directly discharged into irrigation water can be concluded
to be the major pollution route of Cd in farmland soil in Taiwan; (3) material plastic stabilizer (cadmium oxide, CdO), Zn-Pd
compounds and Cu compounds should be the crucial pollution sources to contaminate environment through the route of wastewater
in Cd flow analysis; (4) the crucial pollution sources to contaminate environment through the route of wastewater in Cd flow
analysis were five factories, Coin, Jili, Taiwan Dye, Guangzheng and Mingguan, and they were all categorized as stearate Cd
industries; (5) the typical source of the Cd pollution in soil in Changhua County through the pollution route of wastewater
should be the metal surfacing process industries.
Conclusions This study proved that MFA can be a good tool for identifying Cd flow as well as for recognizing the crux of the problem
concerning incidents of Cd pollution. This study led to the conclusion that the causal relationship between farmland pollution
caused by Cd and stearate Cd factories in Taiwan seemed quite close by way of MFA methodology. In addition, this study also
found that the wastewater discharged from a single metal surfacing process factory will not cause remarkable farmland pollution.
However, the wastewater simultaneously discharged from a group of pollution factories can result in a significant pollution
incident.
Recommendations and Outlook This case study is only a small contribution to the understanding of the toxic material flow related to Cd in the environment.
This study recommends that Taiwanese governmental authorities should not deal with problems on an ad hoc basis, but should
instead deal with Cd pollution problems overall employing control measures. Finally, the more accurate information or data
we can collect, the more reliable results we can identify. Therefore, the quality and quantity of related data used in this
MFA model should be closely scrutinized in order to ensure the most correct and comprehensive investigation on the toxic material
flow. 相似文献