全文获取类型
收费全文 | 908篇 |
免费 | 22篇 |
国内免费 | 263篇 |
专业分类
安全科学 | 29篇 |
废物处理 | 25篇 |
环保管理 | 107篇 |
综合类 | 538篇 |
基础理论 | 219篇 |
污染及防治 | 184篇 |
评价与监测 | 66篇 |
社会与环境 | 24篇 |
灾害及防治 | 1篇 |
出版年
2024年 | 8篇 |
2023年 | 35篇 |
2022年 | 39篇 |
2021年 | 37篇 |
2020年 | 35篇 |
2019年 | 29篇 |
2018年 | 28篇 |
2017年 | 23篇 |
2016年 | 34篇 |
2015年 | 50篇 |
2014年 | 49篇 |
2013年 | 43篇 |
2012年 | 56篇 |
2011年 | 79篇 |
2010年 | 58篇 |
2009年 | 61篇 |
2008年 | 74篇 |
2007年 | 69篇 |
2006年 | 54篇 |
2005年 | 35篇 |
2004年 | 42篇 |
2003年 | 34篇 |
2002年 | 26篇 |
2001年 | 31篇 |
2000年 | 40篇 |
1999年 | 30篇 |
1998年 | 13篇 |
1997年 | 18篇 |
1996年 | 15篇 |
1995年 | 14篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 5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1193条查询结果,搜索用时 875 毫秒
881.
The main objective of this research was to estimate the total mass of nitrogen discharged from various sources in Korea using
the mass balance approach. Three different nitrogen mass balances were presented: (1) agricultural activities including raising
crops and animal husbandry; (2) domestic activities, and (3) activities in forest and urban areas. These nitrogen balances
were combined to estimate riverine discharge of nitrogen to the ocean in national scale. Nitrogen inputs include atmospheric
deposition, biological nitrogen fixation, application of inorganic fertilizers/manures, animal feed/imported foodstuffs, and
meat/fish. Nitrogen outputs include ammonia volatilization, denitrification, human/animal waste generation, crop/meat production,
and riverine discharge to the ocean. The estimated total nitrogen input in Korea was 1,194.5 × 103 tons N/year. Nitrogen discharged into rivers was estimated as 408–422 × 103 tons N/year, of which 66–71% was diffuse in origin. The estimated diffuse discharges for land uses were estimated as 82 × 103 tons N/year from agricultural areas, 7 × 103 tons N/year from forestry and 75 × 103 tons N/year from urban and industrial areas. 相似文献
882.
氮氧化物的污染控制对策 总被引:8,自引:0,他引:8
详细地介绍了日本针对不同的排放源--固定源和流动源--所采取的氮氧化物污染控制对策。对固定源,在实施全国统一的排放标准的基础上,对于一些工厂相对集中、污染问题严重的地区实施总量控制,同时积极促进技术革新以及降低氮氧化物的排放;对流动源所采取的措施有,确定不同车型汽车排放尾气递减的短期目标和长期目标,实施汽车氮氧化物法,积极推进低公害车的普及。通过采取上述措施,在日本,固定源排放的氮氧化物得到了较好 相似文献
883.
于2012年10月—2013年8月对中国北方地区2种典型水库:山区水库(卧虎山、锦绣川)和引黄水库(鹊山、玉清)进行了采样调查,对其水质特征和富营养化现状进行分析研究。结果表明:2类水库水质的最大差异在于山区水库的氮含量显著高于引黄水库,这主要与水源、氮素来源和水库的进水方式有关。山区水库中SD与藻类生物量、TP关系密切;而引黄水库中,影响SD的环境因素较复杂,除藻类生物量和氮、磷外,碱度和水温也与SD密切相关。全年水平上,卧虎山水库营养状态指数显著高于其他水库,属中-富营养水体,锦绣川水库、鹊山水库和玉清水库均属中营养水平。时间上,同类型水库的营养状态指数季节变化基本一致。参与营养状态计算的4个因子中,Chla和TN对营养状态指数的贡献最大,表明这两者是引起2类水库营养状态加重的重要原因。典型的水源及进水方式、流域人类活动类型和强度是影响山区水库和引黄水库营养状态的主要外部因素。 相似文献
884.
Menglei Guo Ying Jiang Junxiang Xie Qianfei Cao Qun Zhang Adams Mabruk Chongjun Chen 《环境科学学报(英文版)》2022,34(5):55-64
The effects of different chemical oxygen demand(COD) concentrations on the anammox granular sludge with Bamboo Charcoal(BC) addition were evaluated in UASB reactor. The results showed that the average total nitrogen(TN) removal efficiency was reduced from85.9% to 81.4% when COD concentration was increased from 50 to 150 mg/L. However, the TN removal efficiency of BC addition reactors was dramatically 3.1%–6.4% higher than that without BC under different COD concentrations. The average diameter o... 相似文献
885.
高浓度氨氮废水处理技术及其发展趋势 总被引:9,自引:0,他引:9
介绍了高浓度氨氮废水的主要来源及其危害性,对国内外主要的高浓度氨氮废水处理工艺进行了分析和对比,并阐述了其发展趋势,为处理高浓度氨氮废水工艺技术的选择提供了参考。 相似文献
886.
Elofsson K 《Environmental management》2006,37(1):54-68
Excess nutrient loads to coastal waters lead to increased production of algae, which when decaying cause oxygen depletion
in bottom sediments, which in turn leads to major changes in marine ecosystems. A cost-minimization model was investigated
in which nitrogen and phosphorus were assumed to interact with respect to algae production. It was investigated under what
conditions only a single nutrient should be decreased and when it is cost-effective to decrease both nutrients. The model
was applied to the Baltic Proper, which is the largest of the seven major basins in the Baltic Sea. Results showed that the
stringency of the environmental target, as well as assumptions regarding substitutability between nutrients, are important
factors to determine the nutrient on which to focus. Uniform decrease rates for emissions are often used in international
agreements, and the results of this model showed that the costs of making such proportional decreases could be substantial. 相似文献
887.
888.
Assessing the Effects of Nutrient Management in an Estuary Experiencing Climatic Change: The Neuse River Estuary, North Carolina 总被引:1,自引:0,他引:1
Eutrophication is a serious water quality problem in estuaries receiving increasing anthropogenic nutrient loads. Managers
undertaking nutrient-reduction strategies aimed at controlling estuarine eutrophication are faced with the challenge that
upstream freshwater segments often are phosphorus (P)-limited, whereas more saline downstream segments are nitrogen (N)-limited.
Management also must consider climatic (hydrologic) variability, which affects nutrient delivery and processing. The interactive
effects of selective nutrient input reductions and climatic perturbations were examined in the Neuse River Estuary (NRE),
North Carolina, a shallow estuary with more than a 30-year history of accelerated nutrient loading and water quality decline.
The NRE also has experienced a recent increase in Atlantic hurricanes and record flooding, which has affected hydrology and
nutrient loadings. The authors examined the water quality consequences of selective nutrient (P but not N) reductions in the
1980s, followed by N reductions in the 1990s and an increase in hurricane frequency since the mid-1990s. Selective P reductions
decreased upstream phytoplankton blooms, but increased downstream phytoplankton biomass. Storms modified these trends. In
particular, upstream annual N and P concentrations have decreased during the elevated hurricane period. Increased flushing
and scouring from storms and flooding appear to have enhanced nutrient retention capabilities of the NRE watershed. From a
management perspective, one cannot rely on largely unpredictable changes in storm frequency and intensity to negate anthropogenic
nutrient enrichment and eutrophication. To control eutrophication along the hydrologically variable freshwater–marine continuum,
N and P reductions should be applied adaptively to reflect point-source–dominated drought and non–point-source–dominated flood
conditions. 相似文献
889.
利用污水处理厂脱水后的污泥,经粉煤灰水分调节后进入动态堆肥装置,好氧发酵成为性状良好的腐殖颗粒,然后经过一定工艺制成一种有机-无机复合化肥,其N、P、K含量达到25%,有机质含量大于30%,含水量小于10%,pH值6~8.将化肥用在农田的水稻种植,水稻的亩产量增产11.4%,各项指标均符合国家标准. 相似文献
890.
为解决污水处理厂污泥成灾的问题,本文阐述了一种将城市污水厂的有机生污泥与干化污泥、辅料一次混拌配料,再经过特制的螺杆挤压造粒机造粒,经过烘干机快速烘干制肥的工艺。该工艺可生产出符合国家标准的颗粒状有机复合肥,该肥料已在公园、草坪绿化中获得应用,具备产业化推广前景。 相似文献