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61.
Binbin Sheng Depeng Wang Xianrong Liu Guangxing Yang Wu Zeng Yiqing Yang Fangang Meng 《Frontiers of Environmental Science & Engineering》2020,14(6):93
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Carbon monoxide (CO) in the surface sea waters is produced predominantly by photochemical processes, oxidized by micro-organisms and outgassed to the atmosphere. to assess carbon monoxide flux from the oceans to the atmosphere, the photochemical production and microbial oxidation of carbon monoxide in the oceanic mixed-layer was investigated during several oeanographic cruises and in the laboratory. the photoproduction rate of carbon monoxide was found to be well correlated to the concentration of dissolved organic carbon (DOC) in coastal and open ocean surface waters. Taking a global average carbon monoxide production rate of 10 ± 2 nmole litre-1 (mg DOC hr)-1 in the surface open ocean water, and 25 ± 7 nmole litre-1 (mg DOC hr)-1 in coastal sea water, at cloud-free summer solar noon, the photochemical production of carbon monoxide in the global oceans is estimated to be at a rate of 1200 ± 200 Tg CO y-1. the microbial carbon monoxide turnover time in the mixed-layer was observed to range from hours in a coastal estuary to 16 days in the Pacific along 1057deg; W in dark incubations. Natural sunlight can largely inhibit the microbial consumption of carbon monoxide in surface water. On a global scale, microbial consumption is responsible for the loss of less than 10% of photochemical produced carbon monoxide in the surface ocean. Field measurements have shown that the net transport of carbon monoxide from the euphotic zone to the underlying deeper ocean water is limited and that the overall life time in surface sea waters is less than 3-4 hours. When combined, these field measurements with the photoproduction and microbial consumption rates obtained, we estimate the oceanic flux to the atmosphere is about 1000 ± 200 Tg CO y-1, which represents the largest single source of atmospheric carbon monoxide. 相似文献
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城市供水中藻类去除技术的研究进展 总被引:1,自引:0,他引:1
日趋严重的水体富营养化已成为全球性的环境问题,藻类及其副产物给传统净水工艺带来了诸多不利影响,增加了水处理难度。本文对饮用水中藻类各种去除技术进行了具体的论述,并系统分析各技术去除效果、局限性,展望了藻类去除技术发展前景。指出目前控制饮用水中藻类污染必须将水源污染综合治理、强化预氧化工艺、优化常规工艺结合起来。 相似文献
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杭州湾表层海水营养盐分布特征及富营养化状况研究 总被引:1,自引:0,他引:1
根据2015年3月和8月杭州湾的海水质量监测数据,分析了该海域的营养盐分布特征以及富营养化状况,结果表明:杭州湾表层海水无机氮变化范围为0.36~4.22 mg/L,活性磷酸盐的含量范围为0.014~1.51 mg/L,化学需氧量含量范围为0.56~3.18 mg/L.该海域无机氮和活性磷酸盐超标严重,表层海水已处于重度富营养化状态,调查站位EI均大于1.该海域表层海水无机氮、活性磷酸盐、化学需氧量和富营养化指数高值区均与陆源入海口、养殖区、排污口等人类活动影响较大的区域有关. 相似文献
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The chemical oxygen demand (COD) and NH3-N removal, membrane fouling, sludge characteristics and microbial community structure in a membrane bioreactor (MBR) coupled with worm reactors (SSBWR) were evaluated for 210 days. The obtained results were compared to those from a conventional MBR (C-MBR) operated in parallel. The results indicated that the combined MBR (S-MBR) achieved higher COD and NH3-N removal efficiency, slower increase in membrane fouling, better sludge settleability and higher activities of the related enzymes in the activated sludge. Denaturing gradient gel electrophoresis was used to analyze the microbial community structures in the C-MBR and the S-MBR. The microbial community structure in the S-MBR was more diverse than that in the C-MBR. Additionally, the slow-growing microbes such as Saprospiraceae, Actinomyces, Frankia, Clostridium, Comamonas, Pseudomonas, Dechloromonas and Flavobacterium were enriched in the S-MBR, further accounting for the sludge reduction, membrane fouling alleviation and wastewater treatment. 相似文献
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This study was conducted to assess the effects of difenoconazole (DFZ), a triazole fungicide, on the hepatic biotransformation system and its bioaccumulation in marine medaka (Oryzias melastigma). Fish were exposed to DFZ (1, 10, 100, 1000 ng/L) for 180 days. The results showed that: (1) The mRNA levels of hepatic CYP1A1, CYP1B, CYP1C1, CYP27B and CYP3A40 were up-regulated, but those of CYP3A38 and CYP27A1 were down-regulated. (2) The activity of ethoxyresorufin-O-deethylase (EROD) and the content of reduced glutathione (GSH) in the liver were increased in the DFZ-treated groups, and glutathione S-transferase (GST) activity was increased in the 100 and 1000 ng/L groups. (3) DFZ was accumulated in the muscle and the biological concentration factors in the 10, 100, and 1000 ng/L groups were respectively 149, 81 and 25. These results suggested that long-term exposure to DFZ at low concentrations would result in a bioaccumulation of this compound and disturb the biotransformation system. 相似文献
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In order to measure groundwater age and design nuclear waste disposal sites, it is important to understand the sorption behavior of tritium on soils. In this study, batch tests were carried out using four soils from China: silty clays from An County and Jiangyou County in Sichuan Province, both of which could be considered candidate sites for Very Low Level Waste disposal; silty sand from Beijing; and loess from Yuci County in Shanxi Province, a typical Chinese loess region. The experimental results indicated that in these soil media, the distribution coefficient of tritium is slightly influenced by adsorption time, water/solid ratio, initial tritium specific activity, pH, and the content of humic and fulvic acids. The average distribution coefficient from all of these influencing factors was about 0.1-0.2 mL/g for the four types of soil samples. This relatively modest sorption of tritium in soils needs to be considered in fate and transport studies of tritium in the environment. 相似文献