首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2499篇
  免费   226篇
  国内免费   909篇
安全科学   321篇
废物处理   101篇
环保管理   216篇
综合类   1783篇
基础理论   347篇
污染及防治   490篇
评价与监测   124篇
社会与环境   129篇
灾害及防治   123篇
  2024年   16篇
  2023年   43篇
  2022年   121篇
  2021年   130篇
  2020年   117篇
  2019年   82篇
  2018年   105篇
  2017年   140篇
  2016年   117篇
  2015年   127篇
  2014年   158篇
  2013年   212篇
  2012年   208篇
  2011年   216篇
  2010年   183篇
  2009年   203篇
  2008年   195篇
  2007年   202篇
  2006年   212篇
  2005年   165篇
  2004年   123篇
  2003年   94篇
  2002年   87篇
  2001年   79篇
  2000年   70篇
  1999年   59篇
  1998年   32篇
  1997年   29篇
  1996年   33篇
  1995年   28篇
  1994年   12篇
  1993年   9篇
  1992年   8篇
  1991年   4篇
  1990年   4篇
  1989年   3篇
  1988年   6篇
  1984年   1篇
  1964年   1篇
排序方式: 共有3634条查询结果,搜索用时 15 毫秒
991.
选取于桥水库上游控制断面——天津果河桥断面1999-2007年的水质监测资料为研究对象,统计该断面6项主要污染项目的超标情况,采用Kendall趋势检验方法对此6项监测指标的月序列进行趋势分析,研究这6项指标在丰水期、平水期、枯水期及年均值的变化趋势.通过分析果河桥断面水质超标情况及该断面主要污染物的变化趋势,得到于桥水库的富营养化特征,结合污染源调查,提出富营养化控制措施.结果表明:于桥水库富营养化的限制因子是磷元素,7-9月蓝藻暴发事件主要是由库区底泥中磷元素的释放所引起的,并且底泥中磷元素的释放受铁氧化-还原控制,上游来水中的铁元素对于桥水库蓝藻暴发有着重要的影响作用.为了防止于桥水库出现藻类暴发的水质恶化事故,需要采取两种关键措施,一是严格控制上游选矿企业富含铁元素尾水的排放,以降低入库水流中铁元素的含量,二是采取底泥氧化或人工曝气等原位技术抑制底泥中磷的释放.  相似文献   
992.
将褐煤样品加入含染料酸性红B的模拟废水中并加碱,褐煤中的腐殖酸溶解,而后加盐酸使腐殖酸絮凝.利用溶解的腐殖酸结合与褐煤颗粒表面的吸附作用,达到去除废水中该染料的目的.结果显示,褐煤对酸性红B具有很好地去除效果,但受到作用时间、溶液pH值、离子强度等因素的影响.要达到最佳去除效果,结合过程最少需要120 min,吸附过程需要480 min.初始质量浓度越高,废水中酸性红B的去除率越低,但当初始质量浓度在250 ~ 500 mg/L时,去除率最小,但变化不大.结合过程pH值升高与吸附过程pH值降低均有利于该染料的去除.褐煤投加量增加,去除率提高,当初始质量浓度为250mg/L,褐煤投加量达到4mg/mL时的去除率达99%.离子强度的增加有利于褐煤对酸性红B的去除作用.  相似文献   
993.
994.
Concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were measured in 28 surface soils samples collected from Urumqi, northwest China, for examination of distributions, source contributions, and potential health effects. The results indicated that the sum of 16 PAHs concentration ranged from 331 to 15,799 μg?kg?1 (dw) in soils, with a mean of 5,018?±?4,896 μg?kg?1 (n?=?28). The sum of seven carPAHs concentration ranged from 4 to 1,879 μg?kg?1 (dw; n?=?28). The highest ∑PAHs concentrations were found at roadsides and industrial sites, followed by those at parks, rural areas, and business/residential areas. Coal combustion, emission of diesel and gasoline from vehicles, and petroleum source were four sources of PAHs as determined by PMF analysis, which contributed 51.19, 19.02, 18.35, and 11.42 % to the PAH sources, respectively. Excellent coefficients of correlation between the measured and predicted PAHs concentrations suggested that the PMF model was very effective to estimate sources of PAHs in soils. Incremental lifetime cancer risk values at the 95th percentile due to human exposure to surface soils PAHs in Urumqi were 2.02?×?10?6 for children and 2.72?×?10?5 for adults. The results suggested that the current PAHs levels in soils from Urumqi were pervasive and moderately carcinogenic to children and adults.  相似文献   
995.
高等水生植物中镉的富集分配规律及危害   总被引:6,自引:1,他引:6  
本文报道了四种水生植物——狐尾藻、水葫芦、紫背萍、荇菜对水体镉污染的反应和它们的净化作用。其结果是:植物的不同种类、不同器官、不同生态习性的不同镉富集量;水体镉浓度与植物的富集量之间有显著相关;富集系数因植物种和器官不同而异;随镉浓度的上升,叶细胞膜受损,叶绿素含量和叶绿素a/b比率下降;植物内部的破坏先于外部;植物的抗性顺序为水葫芦>狐尾藻>荇菜>紫背萍。作者认为水葫芦对水体镉污染具有较理想的净化作用,紫背萍则是较好的监测植物。  相似文献   
996.
为了提高高校优质中水的处理与回用率,提出了适用于高校优质中水的处理与回用系统,设计了中水原位处理设备,并进行了试验验证.结果表明,沉淀-SOBMR-过滤设备能够实现无动力、自动化运行,尤其适合于盥洗和洗浴废水的处理.沉淀单元对盥洗废水COD和SS去除率分别为23.8%和55.7%;SOBMR单元对盥洗废水COD和SS去除率分别为35.8%和27.9%;过滤单元能有效去除废水中绝大部分SS,且能耐受SS冲击负荷,对废水COD去除率先增后降,受水力负荷的影响,负荷越小,处理效果越好.整个系统出水水质满足杂用水对COD、SS和色度等要求,可用于冲厕和杂用.每套处理装置可节约水资源151.2 m3/a,设备投资回收期为2.01年,具有巨大的经济效益.  相似文献   
997.
处理啤酒废水的厌氧流化床操作特性的研究   总被引:1,自引:0,他引:1  
试验表明,自制厌氧流化床(AFB)反应器对温度的变化、上升流速等环境的变化都具备良好的稳定性.它的处理温度控制在30±2℃范围,上升表观流速控制为19.1 m/h左右,回流比控制为8:1,水力停留时间在6.9 h左右,废水COD去除率可达80%以上.该AFB反应器能够承受高达30.65 kg COD/m3·d的有机容积负荷,其COD去除率也达到了73%~81%,产气速率系数为0.55~0.612 m2/kg COD.同时,也对实验中出现的偏析现象进行了分析.  相似文献   
998.
Zeng P  Zhuang WQ  Tay ST  Tay JH 《Chemosphere》2007,69(11):1751-1757
The precultured aerobic granules with special degradabilities could be used as a feasible bioseed for enhancement of aerobic granulation systems. In practice, the storage stability, physicochemical characteristics, and recovering efficiency of granules are crucial for a long-distance transportation and successful application. In this study, phthalic acid (PA)-degrading aerobic granules were cultivated and stored for 8 wk at 4 °C. The granular size, settling ability as well as structure integrity was found stable during the storage period. It was observed that the upper 1/3 part of granules stored in the reagent bottle turned to black color, while the lower 2/3 part granules did not significantly change color (brown–yellow) after the 8-wk storage. The black and brown–yellow color PA-degrading granules were manually separated and re-inoculated into two identical sequencing batch reactors for reviving the PA degradation capability. After a 7 d operation, both black and yellow granules restored their activities to the levels before storage, in terms of total organic carbon removal efficiency (100%), specific oxygen uptake rate (59 mg g VSS−1 h−1), and adenosine triphosphate content (0.016 mg g VSS−1). This study demonstrated that aerobic granules grown on a complex substrate could tolerate storage conditions and rapidly restored their bioactivities toward the target pollutant. The results also shed the light on the future application of precultured aerobic granules with unique functions for biodegradation and bioremediation purpose.  相似文献   
999.
Xu J  Yu Y  Wang P  Guo W  Dai S  Sun H 《Chemosphere》2007,67(7):1408-1414
Fourteen surface sediment samples were collected from Lanzhou Reach of Yellow River, China in July 2005. The concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) were determined by gas chromatography equipped with a mass spectrometry detector (GC-MS). Total concentrations of the PAHs ranged from 464 to 2621 ng/g dry weight. Sediment samples with the highest PAH concentrations appeared at the downstream of Lanzhou City, where there was the biggest wastewater discharge pipeline from Lanzhou Oil Refinery Factory and Lanzhou Chemical Industry Company. Municipal sewage also contributed to the PAH contamination in the sediments. A correlation existed between the sediment organic carbon content (f(oc)) and the total PAH concentrations (r(2)=0.57), suggesting that sediment organic carbon content played an important role in controlling the PAHs levels in the sediments. According to the observed molecular indices, PAHs contamination in Lanzhou Reach of Yellow River originated both from the high-temperature pyrolytic processes and from the petrogenic source, showing a mixed PAH input pattern, which was also confirmed by the results of a principal component analysis (PCA). According to the numerical effect-based sediment quality guidelines (SQGs) of the United States, the levels of PAHs at most studied sites in Lanzhou Reach of Yellow River should not exert adverse biological effects. Although at some sites (such as S10, S12, etc.) one PAH may exceed the effects range low (ERL), individual PAH did not exceed the effects range median (ERM). The results indicated that sediments in all sites should have potential biological impact, but should have no impairment.  相似文献   
1000.
近年来,流感常用药盐酸金刚烷胺的产量不断增大,然而,其生产过程中产生的废水由于得不到有效处理,引起较大污染。以盐酸金刚烷胺生产过程中产生的胺化废水和溴化废水为原水,利用Fenton-超声联合工艺进行处理,主要研究反应时间、初始pH、H2O2投加量和H2O2/Fe2+的投加比和声能密度等操作条件对于金刚烷胺制药废水处理效果的影响。实验结果表明,优化处理条件下,Fenton-超声联合工艺对金刚烷胺制药废水中TOC去除效果最高达到65.6%。超声和Fenton的联合产生了良好的协同效果,Fenton-超声联合工艺对金刚烷胺制药废水的处理效果比单独超声和单独Fenton处理效果之和高18%,大大提高了废水中有机物的去除效果。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号