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101.
城市水样中首次检出痕量硝基多环芳烃(NO2—PAH)   总被引:6,自引:0,他引:6  
马明生  康致泉 《环境化学》1994,13(6):543-549
本文利用还原衍生化高分辨GC-ECD法,采用双柱定性首次在城市地表水样中检出环境潜在致癌物-硝基多环芳烃(NO2-PAH),结果表明,在不同的水样中共检出包括动物致癌物2-硝基萘在内的八种NO2-PAH。河水和饮用水中均有ppt级NO2-PAH存在,其中溶解度较大的两环硝基多环芳烃的含量高于三环以上的。饮用水中NO2-PAH的浓度低于与其相邻的河水中相应硝基多环芳烃的含量,经煮沸处理后,饮用水中N  相似文献   
102.
微生物燃料电池(microbial fuel cell,MFC)利用微生物催化剂将其代谢能直接转化为电能,具有原料广泛、反应条件温和、清洁高效等优点.简述了MFC的工作原理及分类,总结了用于污水处理的MFC的性能及其影响因素.探讨了MFC在实际应用中的瓶颈,并展望其在污水处理中的应用前景.  相似文献   
103.
A biocathode with microbial catalyst in place of a noble metal was successfully developed for hydrogen evolution in a microbial electrolysis cell (MEC). The strategy for fast biocathode cultivation was demonstrated. An exoelectrogenic reaction was initially extended with an H2-full atmosphere to enrich Ha-utilizing bacteria in a MEC bioanode. This bioanode was then inversely polarized with an applied voltage in a half-cell to enrich the hydrogen-evolving biocathode. The electrocatalytic hydrogen evolution reaction (HER) kinetics of the biocathode MEC could be enhanced by increasing the bicarbonate buffer concentration from 0.05 mol·L-1 to 0.5 mol· L-1 and/or by decreasing the cathode potential from -0.9 V to - 1.3 V vs. a saturated calomel electrode (SCE). Within the tested potential region in this study, the HER rate of the biocathode MEC was primarily influenced by the microbial catalytic capability. In addition, increasing bicarbonate concentration enhances the electric migration rate of proton carriers. As a consequence, more mass H+ can be released to accelerate the biocathode-catalyzed HER rate. A hydrogen production rate of 8.44 m3. m 3. d1 with a current density of 951.6 A. m-3 was obtained using the biocathode MEC under a cathode potential of - 1.3 V vs. SCE and 0.4 mol· L-1 bicarbonate. This study provided information on the optimization of hydrogen production in biocathode MEC and expanded the practical applications thereof.  相似文献   
104.
River waters in China have dual contamination by nutrients and recalcitrant organic compounds. In principle, the organic compounds could be used to drive denitrification of nitrate, thus arresting eutrophication potential, if the recalcitrant organics could be made bioavailable. This study investigated the potential to make the recalcitrant organics bioavailable through photocatalysis. Batch denitrification tests in a biofilm reactor demonstrated that dual-contaminated river water was short of available electron donor, which resulted in low total nitrogen (TN) removal by denitrification. However, the denitrification rate was increased significantly by adding glucose or by making the organic matters of the river water more bioavailable through photocatalysis. Photocatalysis for 15 min increased the Chemical Oxygen Demand (COD) of the river water from 53 to 84 mg·L-1 and led to a 4-fold increase in TN removal. The increase in TN removal gave the same effect as adding 92 mg·L-1 of glucose. During the photocatalysis experiments, the COD increased because photocatalysis transformed organic molecules from those that are resistant to dichromate oxidation in the COD test to those that can be oxidized by dichromate. This phenomenon was verified by testing photocatalysis of pyridine added to the river water. These findings point to the potential for N removal via denitrification after photocatalysis, and they also suggest that the rivers in China may be far more polluted than indicated by COD assays.  相似文献   
105.
张帆  宋阳  胡春  吕来 《环境科学》2021,42(5):2360-2369
多相催化臭氧化技术因能有效去除水中有机污染物而受到广泛关注.然而,基于单一位点氧化还原的金属氧化物催化臭氧化过程存在速率限制步骤,使活性受到抑制,极大地限制了多相催化臭氧化技术的实际应用.为解决这一瓶颈,以过渡金属物种Fe和Ti对金属氧化物γ-Al2O3基底进行晶格掺杂制备出新型双反应中心催化剂FT-A-1 DRCs.通过XRD、TEM和XPS等技术对其形貌结构和化学组成进行了表征分析,证明Fe和Ti对于Al的晶格取代,形成表面贫富电子微区(富电子Fe微中心和缺电子Ti微中心).FT-A-1 DRCs被用于催化臭氧化过程,对布洛芬等一系列难降解有机污染物的去除表现出优异的活性和稳定性.利用EPR和电化学技术揭示了界面反应机制.发现在催化臭氧化过程中,O3/H2O在富电子微中心被定向还原产生·OH,而污染物可在缺电子微中心作为电子供体而被氧化,为反应体系持续提供电子.这一反应过程利用污染物自身的能量实现了污染物的双途径降解(·OH攻击和直接电子供体),突破了金属氧化物催化臭氧化过程存在速率限制步骤.  相似文献   
106.
A study was conducted to investigate the effects of metal mixtures on the Chironomus plumosus. Two methods of preparing the mixtures were used, the Toxic Unit (TU) method and the parts per million (PPM) + PPM method. A comparison was undertaken between the two methods to observe the ease with which (1) experiment could be conducted and (2) whether LC50 values could be obtained. In this study, it was noted that the PPM + PPM method was an easier method to conduct metal mixture experiments as the LC50 values could be easily calculated for individual metals and compared with the LC50 values of metals obtained from single metal experiments. The findings showed that the LC50 value for zinc (Zn) was more toxic for chromium (Cr) when it was reduced from 9.6 to 0.3 mg L?1, with silver the LC50 value became 3.6 mg L?1, 4.5 mg L?1 with nickel (Ni). In the PPM + PPM method, the LC50 value for Zn was observed to be 10.2 mg L?1 when in mixture with chromium, 23.8 mg L?1 with silver, and 13.4 mg L?1 with Ni. Changes in the 96 h LC50 value were found to be significant for all metals.  相似文献   
107.
A study was conducted on the Babylon snail (Babylonia areolata) to examine the effects of copper (Cu), cadmium (Cd), nickel (Ni), and zinc (Zn) on different life stages of this gastropod. Metal toxicity significantly varied according to the life stage of the snail. The different LC50 values obtained were 0.51, 5.49, 0.31, and 0.2 ppm for Cu, Zn, Cd, and Ni for the larval stage and 4.98, 15.19, 0.91, and 1.21 ppm at the juvenile stage and 8.54, 17.52, 1.14, and 1.44 ppm in the adult stage. Studies were also conducted on the effects of dual metal concentrations and experiments were repeated with temperature as a variable. Results demonstrated that metal toxicity values were altered depending on the metals involved in the combination as well as temperature under which the experiment was conducted.  相似文献   
108.
传统电Fenton反应通过电化学方法产生H2O2,需外加电源,能耗大,成本高。基于MFC持续产电并可驱动阴极电Fenton系统运行的特点,本研究以铁复合碳毡为阴极电极,构建了微生物燃料电池驱动的生物电Fenton系统,探讨了铁复合碳毡及阴极pH对偶氮染料(金橙I号)脱色的影响。结果发现,铁复合碳毡脱色效果均好于普通碳毡。当pH为3时,4 h后Fe@Fe2O3/CF阴极脱色率达91.7%,明显高于α-FeOOH/CF和FeAlSi/CF的83.4%和69.9%。扫描电镜发现,Fe@Fe2O3以微粒状结构附着于碳毡表面,比表面积增大,可能是Fe@Fe2O3/CF脱色性能改善的主要原因。研究表明,低pH有利于生物电Fenton反应的进行。当pH由3.0提高至5.0时,Fe@Fe2O3/CF阴极脱色率降低至47.1%。阴极室染料脱色与阳极室废水TOC削减呈线性相关,说明阳极生物氧化是驱动阴极生物电Fenton反应的原动力。本研究提供了一种能自我维持、无需外源电力的生物电Fenton系统,为印染废水脱色提供了崭新的途径。  相似文献   
109.
黄河三角洲二元结构与多元可持续发展初探   总被引:4,自引:1,他引:3  
黄河三角洲由石油资源的开发而兴起,其区位条件和油气资源条件都十分优越,但目前仍处于经济发达地区的低谷区。通过对二元结构系数的定量分析,发现该地区具有明显的复合二元结构特征,即“油地+城乡”,二元结构是制约三角洲持续发展的一个重要限制性因素。目前,石油产业的全面改组改制、优越的外部环境和自身基础条件、东营港扩建及其附属加工制造业基地的立项、综合性交通运输网络体系的形成等都是三角洲全面发展的难得机遇。要实现多元可持续发展的目标,必须转变观念,由“以油建城”到“以港兴城”、大力发展资源深加工工业和具有竞争优势的制造业;构建高效生态农业经济体系;推进城市的“内聚式”发展。  相似文献   
110.
A new system composed of a sequential flat plate and parabolic dish solar collector was applied to enhance the solar desalination productivity. Heated saline water was desalinated using the evaporation/condensation principle and an effort was made to achieve higher distillate production compared to previous studies. Desalination efficiency values were calculated between 23% and 57%. Maximum desalinated water productions were obtained as 1,038 mL/m2.h in autumn and 1,402 mL/m2.h in summer. The cost of solar desalination system was found as economically feasible with 3 years’ payback period and the produced water cost of 0.014 $/L. Physicochemical analyses revealed that as a result of the desalination process, salinity level decreased from 35.6‰ to 0.0–0.1‰, chloride concentration decreased from 21,407 mg/L to 10 mg/L, and electrical conductivity decreased from 53.1 mS/cm to 0.11 mS/cm.  相似文献   
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