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221.
试论我国环境税的设立与完善 总被引:3,自引:0,他引:3
从西方各国的实践及可供我国借鉴的措施等诸方面对环境税的设立及完善加以探讨,就建立环境税逐步完善费改税、公平税负及建立完善的彼此协调的环境税费体系进行了思考,并提出了一些建议。 相似文献
222.
在湖泊沉积物表层存在着强烈的生物作用 ,使SO2 -4 转变成S2 -,然后和Fe2 + 结合而固定在沉积物中 ,这种SO2 -4 的清除机制具有重要的环境意义。本文论述了H2 S的产生和各种形态硫转变成SO2 -4 的酶促反应机制 ,并阐述了不同微生物电子传递载体、最终电子受体和电子进入传递链的部位的差异以及生成ATP的数目和环境效应的差异。 相似文献
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为研究唐山市大气PM2.5中元素组成特征及其来源,于2017年10月19日—2018年1月31日(秋冬季)在唐山市的超级站(典型城市站点)、开平站(工业站点)和古冶站(工业站点)开展了PM2.5的手工连续采样,定量分析测定了PM2.5中23种无机元素.结果表明:Si、Al、Ca和Na等地壳元素的质量浓度均在10月最高,在1月最低.10月,ρ(Cr)在开平站最高(0.020 0 μg/m3),随后逐月略微降低,其主要受钢铁冶炼工业的减产和限产影响.多数重金属元素质量浓度在11月或12月最高,包括Zn、Pb、Mn、Cu、Ni、Se、V、Cd和Co,其可能受燃煤取暖影响.Cd、Zn、Pb和Cu四种元素的富集因子值分别为2 677、616、422和77,均达到极强富集,且均受人为排放源影响最大.基于因子分析法得出,唐山市大气PM2.5中元素的主要来源有燃煤源、钢铁工业源与扬尘源的混合源、交通源以及土壤扬尘源,其方差贡献率分别为56.3%、21.6%、7.1%、5.4%.研究显示,秋冬季唐山市大气颗粒物PM2.5中元素最主要的污染来源为工业源、燃煤源和扬尘源. 相似文献
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统计分析2014~2017年北京城区霾污染发生情况,利用HYSPLIT模式对4年内气流来向进行聚类计算,识别区域内的主要污染传输通道和潜在污染源区分布及变化.结果显示,研究期间北京市城区空气质量状况整体呈改善趋势,灰霾时发生率从2014年的50.6%降至2017年33.7%,灰霾日数由165d降至78d,每年10月到次年采暖结束的3月灰霾发生较为集中.不同强度霾发生频率逐年下降,秋、冬季灰霾发生频率及污染强度均逐步降低.冀东南平原区、太行山东麓以及燕山南麓沿线为京津冀地区的3条主要污染传输通道,传输高度均在近地1000m内,期间通道轨迹对应北京城区PM2.5平均达124.1μg/m3,其出现频率在2014~2017年逐年减小,并且各年当中同类轨迹所对应的北京PM2.5均呈逐年下降趋势.北京城区PM2.5的主要潜在源区从华北平原和渤海天津港区域逐渐缩小至冀中南和鲁西北地区,且传输通道区域污染贡献率逐年降低,有利的天气形势和人为的区域减排是近年空气质量改善的2大主因. 相似文献
226.
Fatma Krichen Wafa Karaoud Nadhem Sayari Assaâd Sila Fatma Kallel Semia Ellouz-Chaabouni Ali Bougatef 《Journal of Polymers and the Environment》2016,24(2):166-175
Sulfated polysaccharides were isolated from two Tunisian fish skins grey triggerfish (Balistes capriscus) (GTSP) and smooth hound (Mustelus mustelus) (SHSP). Their chemical and physical characteristics were investigated. The Analysis of surface morphology by scanning electron microscopy of both sulfated polysaccharides displayed the same shape with netted structure. The antioxidant activities of GTSP and SHSP were evaluated using various in vitro antioxidant assays: 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, reducing power, β-carotene bleaching inhibition assay (IC50 GTSP = 0.5 mg mL?1 and IC50 SHSP = 0.6 mg mL?1) and DNA nicking assay. Both sulfated polysaccharides exhibited good antioxidant activities. The sulfated polysaccharides showed strong angiotensin I-converting enzyme inhibitory activities (IC50 GTSP = 0.16 mg mL?1 and IC50 SHSP = 0.18 mg mL?1). These results revealed that GTSP and SHSP exhibited significant antihypertensive activities. Overall, the results indicated that grey triggerfish and smooth hound skins can be used to generate high value-added products, thus offering a valuable source of bioactive sulfated polysaccharides for application in wide range of biotechnological applications. 相似文献
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M.A. Batiha A.A.H. Kadhum A.B. Mohamad M.S. Takriff Z. Fisal W.R. Wan Daud M.M. Batiha 《Process Safety and Environmental Protection》2009,87(2):121-134
Many pesticides used in agricultural activities are considered environmentally non-volatile. The main purpose of this paper is to develop multimedia model to be used as a tool to predict the overall fate and transport of non-volatile organic chemicals (NVOCs) dynamic in the agro-ecosystem. The model was developed based on the EQuilibrium Criterion (EQC) model for type 2 chemicals introduced by Mackay and colleagues in 1996. Mackay’s model only considered four environmental compartments, which are air, water, soil and sediment. The present model adds the vegetation compartment, in addition to previous compartments that shape the agro-ecosystem. The vegetation compartment is described by two sub-compartments consisting of the above ground plant (AGP) and roots. The model was parameterized for the Cameron Highlands region, Malaysia, and runs with an illustrative emission rate of 1 kg h?1 into the air for three selected pesticides, namely, mancozeb, spinosad and chlorosulfuron. The simulation results with and without vegetation compartment were compared. The estimated results indicating that the AGP captures 99.9% of introduced NVOCs (i.e., of 100% or 1 kg h?1) and transfers them to the ground below due to the slight degradation losses of 10?4% and the non-volatility property of the evaluated chemicals. Root uptake of chlorosulfuron accounted the highest removal process from soil while degradation of spinosad in the soil is the major loss mechanism. Leaching to groundwater loss for mancozeb is about 2-fold greater than that of degradation, which together accounted the major removal process from soil. Based on the estimated results of mass distribution on the overall system, vegetation compartment accumulates 0.04%, 0.5% and 2.02% of the mancozeb, spinosad and chlorosulfuron, respectively. 相似文献
230.
The optimization of sewage treatment by the combination of high rate biological treatment with chemical coagulation to remove both organic and inorganic pollutants with special reference to phosphorus has been investigated. In an attempt to study the minimum biological treatment which will not adversely affect the efficiency of the combined system, three different organic loads, namely, 9.48, 20.0 and 27.85 BOD5.m?2d?1, were examined. The coagulants used were ferric chloride and alum. Calcium oxide was used as a coagulant aid with ferric chloride. The results obtained showed that the efficiency of the combined system was found to be slightly affected by the organic load. The combined treatment technique used in this investigation proved to be very promising in removing both inorganic and organic pollutants. 相似文献