全文获取类型
收费全文 | 517篇 |
免费 | 3篇 |
国内免费 | 79篇 |
专业分类
安全科学 | 18篇 |
废物处理 | 9篇 |
环保管理 | 58篇 |
综合类 | 233篇 |
基础理论 | 65篇 |
污染及防治 | 153篇 |
评价与监测 | 55篇 |
社会与环境 | 8篇 |
出版年
2023年 | 11篇 |
2022年 | 16篇 |
2021年 | 12篇 |
2020年 | 15篇 |
2019年 | 13篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 19篇 |
2015年 | 37篇 |
2014年 | 28篇 |
2013年 | 26篇 |
2012年 | 28篇 |
2011年 | 46篇 |
2010年 | 31篇 |
2009年 | 44篇 |
2008年 | 54篇 |
2007年 | 44篇 |
2006年 | 30篇 |
2005年 | 16篇 |
2004年 | 14篇 |
2003年 | 13篇 |
2002年 | 15篇 |
2001年 | 8篇 |
2000年 | 19篇 |
1999年 | 7篇 |
1998年 | 1篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有599条查询结果,搜索用时 31 毫秒
571.
572.
573.
Microbial nitrogen transformation potential in surface run-off leachate from a tropical landfill 总被引:1,自引:0,他引:1
Ammonium is one of the major toxic compounds and a critical long-term pollutant in landfill leachate. Leachate from the Jatibarang landfill in Semarang, Indonesia, contains ammonium in concentrations ranging from 376 to 929 mg N L−1. The objective of this study was to determine seasonal variation in the potential for organic nitrogen ammonification, aerobic nitrification, anaerobic nitrate reduction and anaerobic ammonium oxidation (anammox) at this landfilling site. Seasonal samples from leachate collection treatment ponds were used as an inoculum to feed synthetic media to determine potential rates of nitrogen transformations. Aerobic ammonium oxidation potential (<0.06 mg N L−1 h−1) was more than a hundred times lower than the anaerobic nitrogen transformation processes and organic nitrogen ammonification, which were of the same order of magnitude. Anaerobic nitrate oxidation did not proceed beyond nitrite; isolates grown with nitrate as electron acceptor did not degrade nitrite further. Effects of season were only observed for aerobic nitrification and anammox, and were relatively minor: rates were up to three times higher in the dry season. To completely remove the excess ammonium from the leachate, we propose a two-stage treatment system to be implemented. Aeration in the first leachate pond would strongly contribute to aerobic ammonium oxidation to nitrate by providing the currently missing oxygen in the anaerobic leachate and allowing for the growth of ammonium oxidisers. In the second pond the remaining ammonium and produced nitrate can be converted by a combination of nitrate reduction to nitrite and anammox. Such optimization of microbial nitrogen transformations can contribute to alleviating the ammonium discharge to surface water draining the landfill. 相似文献
574.
Microalgae are the most important primary productive forces in shrimp aquaculture systems. Microalgae not only provide oxygen and natural food for aquaculture objects, but they also absorb nitrogen (N) and phosphorus (P) to reduce water eutrophication. However, there are great differences in N and P absorption among different strains of microalgae. To maintain the sustainable development of shrimp aquaculture, the growth performances of eight microalgal strains in Penaeus vannamei sewage and N and P removal rates were investigated under laboratory conditions. The results indicated that the eight microalgal strains could reduce the N and P content in P. vannamei sewage to some extent. Microcystis aeruginosa, Chlamydomonas sp., and Chlorella pyrenoidosa grew very well, with average growth rates of 0.309 3, 0.246 9, and 0.215 5, respectively. There were significant differences in the removal efficiency among the different strains. The removal rates of total N by M. aeruginosa, Chlamydomonas sp., and C. pyrenoidosa were 74%, 69%, and 60%, respectively, at the end of the experiment, which were higher than the other species. M. aeruginosa and Chlamydomonas sp. had better total P removal efficiency than those of the other microalgal strains and removal rates were greater than 60%, and the second highest total P removal efficiency was by C. pyrenoidosa. Different types of microalgal strains had different absorption rates of different morphological nitrogen. M. aeruginosa and Chlamydomonas sp. had the highest nitrate nitrogen removal rate (approximately 70%). Chlamydomonas sp. had a fast and persistent removal rate of ammonia nitrogen, with the removal rate being as high as 100%. The removal efficiency of M. aeruginosa and C. pyrenoidosa were a little slower, and those of Scenedesmus obliquus, Synedra sp., and Navicula graciloides were the slowest. After 16 d, the removal rate reached more than 90%. Cryptomonas obovate and C. pyrenoidosa displayed the best removal rate of nitrite nitrogen, and the removal rate reached 80% on day 8, and the removal rate of C. obovata was more persistent. These results can provide scientific reference for the orientation and use of microalgae to remove pollutants in tailings water from shrimp aquaculture systems. © 2018 Science Press. All rights reserved. 相似文献
575.
Basic principles and ecological consequences of changing water regimes on nitrogen cycling in fluvial systems 总被引:8,自引:0,他引:8
Understanding the environmental consequences of changing water regimes is a daunting challenge for both resource managers
and ecologists. Balancing human demands for fresh water with the needs of the environment for water in appropriate amounts
and at the appropriate times are shaping the ways by which this natural resource will be used in the future. Based on past
decisions that have rendered many freshwater resources unsuitable for use, we argue that river systems have a fundamental
need for appropriate amounts and timing of water to maintain their biophysical integrity. Biophysical integrity is fundamental
for the formulation of future sustainable management strategies. This article addresses three basic ecological principles
driving the biogeochemical cycle of nitrogen in river systems. These are (1) how the mode of nitrogen delivery affects river
ecosystem functioning, (2) how increasing contact between water and soil or sediment increases nitrogen retention and processing,
and (3) the role of floods and droughts as important natural events that strongly influence pathways of nitrogen cycling in
fluvial systems. New challenges related to the cumulative impact of water regime change, the scale of appraisal of these impacts,
and the determination of the impacts due to natural and human changes are discussed. It is suggested that cost of long-term
and long-distance cumulative impacts of hydrological changes should be evaluated against short-term economic benefits to determine
the real environmental costs. 相似文献
576.
In this paper, the role of nutrient transports between marine basins is investigated for cost-effective solutions to predetermined marine basin targets. The interdependent advective nutrient transports as well as retentions among the seven major marine basins of the Baltic Sea are described by input-output analysis. This is in contrast to prior economic studies of transboundary water pollution that include only direct transport between the basins. The analytical results show that the difference in impacts between transport specifications depends mainly on the openness of the basins, that is, their transports with other basins. The application on Baltic Sea shows significant differences in costs and policy design between the nutrient transport specifications. The reason is that the Sea is characterized by long water and nutrient residence times, so relatively large part of nutrients are transported among basins. 相似文献
577.
Nitrogen and phosphorus cycling in a eutrophic Louisiana freshwater lake system (Lac des Allemands) was studied. Nutrients from runoff entering the lake, as well as sediment-interstitial and lake water nitrogen and phosphorus fractions, were measured seasonally. Sedimentation rates in the lake were determined using137Cs dating.Phosphorus levels in the lake were found to be largely dependent on concentrations in the incoming bayou water from upland drainage. Lake water concentrations appear to respond to fluctuations in incoming waters. Laboratory equilibrium studies showed bottom sediments in the lake are a major sink for the incoming dissolved orthophosphate phosphorus. Total nitrogen concentrations in the lake water generally exceeded incoming runoff concentrations, suggesting fixation by the large blue-green algae population in the lake as being the major source of nitrogen to the system.Sedimentation ranged from 0.44 cm/year to 0.81 cm/year, depending on the proximity to the inlet bayous. Even though the lake is eutrophic the sediment served as a buffer by removing large amounts of carbon, nitrogen, and phosphorus through sedimentation processes. Carbon, nitrogen, and phosphorus were accumulating in the sediment at rates of 60, 7.1, and 1.1 g/m2/year, respectively.The water quality of the lake is likely to continue to decline unless measures are taken to reduce municipal, industrial, and agricultural inputs of phosphorus into the lake. 相似文献
578.
被动式吸收采样监测空气中二氧化硫、二氧化氮主要影响因素探讨 总被引:3,自引:0,他引:3
论述了关于被动式吸收采样法用于监测环境空气中的二氧化硫、二氧化氮的影响因素,包括风向、风速、温度、湿度、吸收液种类及浓度、吸收液加入方式等;提出在四季温差较大地区,监测结果的计算中需引入温度校正系数;建议采样时间以2~3周为宜。 相似文献
579.
浅谈河套灌区农田氮磷流失量及对乌梁素海输入量的估算 总被引:1,自引:0,他引:1
内蒙古的乌梁素海近年来出现了严重的富营养化现象,入湖的营养源主要有工业污染源、农业面源、城市生活废水.由于该湖主要水源为农田退水,而且城市生活废水和工业污染源都是经过河套灌区的总排水渠流入乌梁素海,本文通过调查河套灌区农田氮磷的流失量及估算向乌梁素海的输入量,确定各污染源的入湖量,特别是农田面源的入湖量对乌梁素海的富营养化防治是非常重要的. 相似文献
580.