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   951篇
  免费   121篇
  国内免费   401篇
安全科学   52篇
废物处理   11篇
环保管理   63篇
综合类   776篇
基础理论   204篇
污染及防治   87篇
评价与监测   164篇
社会与环境   43篇
灾害及防治   73篇
  2024年   6篇
  2023年   45篇
  2022年   56篇
  2021年   82篇
  2020年   73篇
  2019年   62篇
  2018年   64篇
  2017年   58篇
  2016年   81篇
  2015年   63篇
  2014年   61篇
  2013年   94篇
  2012年   72篇
  2011年   83篇
  2010年   58篇
  2009年   48篇
  2008年   38篇
  2007年   51篇
  2006年   47篇
  2005年   43篇
  2004年   37篇
  2003年   37篇
  2002年   35篇
  2001年   25篇
  2000年   26篇
  1999年   21篇
  1998年   23篇
  1997年   7篇
  1996年   15篇
  1995年   14篇
  1994年   12篇
  1993年   9篇
  1992年   7篇
  1991年   2篇
  1990年   7篇
  1989年   2篇
  1986年   3篇
  1984年   1篇
  1982年   2篇
  1976年   2篇
  1972年   1篇
排序方式: 共有1473条查询结果,搜索用时 15 毫秒
991.
In 2000, 63 (polished) white rice samples were collected in eight administrative areas all over South Korea and analyzed for 16 elements by inductively coupled plasma atomic emission spectrometry (ICP-AES). Potassium had the highest content, next to Mg, Ca, Si, Zn, Na, Al and Fe. Most of the samples contained worldwide average concentrations of essential and trace elements in rice grains reported by various researches. For inter-area differences in those elements in the rice, the statistical analysis showed no significant differences (p > 0.05) among the eight administrative areas, suggesting that inter-area differences were not substantial in most cases. Thus, the present data can be used as national background levels of elements in rice produced in South Korea. Using the published data on daily consumption of rice in South Korea, it was possible to estimate the daily intake of As, Cd, Cu, Pb and Zn via rice. The results showed that a regular consumption of rice produced in Korea plays an important role in accumulation of essential and trace elements in Korean, especially for farm-households consuming relatively large amounts of rice.  相似文献   
992.
This paper describes concentration amounts of arsenic (As), particulate mercury (Hg), nickel (Ni) and lead (Pb) in PM10 and PM2.5, collected since 1993 by the Technological and Nuclear Institute (ITN) at different locations in mainland Portugal, featuring urban, industrial and rural environments, and a control as well. Most results were obtained in the vicinity of coal- and oil-fired power plants. Airborne mass concentrations were determined by gravimetry. As and Hg concentrations were obtained through instrumental neutron activation analysis (INAA), and Ni and Pb concentrations through proton-induced X-ray emission (PIXE). Comparison with the EU (European Union) and the US EPA (United States Environmental Protection Agency) directives for Ambient Air has been carried out, even though the sampling protocols herein – set within the framework of ITN's R&D projects and/or monitoring contracts – were not consistent with the former regulations. Taking this into account, 1) the EU daily limit for PM10 was exceeded a few times in all sites except the control, even if the number of times was still inferior to the allowed one; 2) the EU annual mean for PM10 was exceeded at one site; 3) the EPA daily limit for PM2.5 was exceeded one time at three sites; 4) the EPA annual mean for PM2.5 was exceeded at most sites; 5) the inner-Lisboa site approached or exceeded the legislated PMs; 6) Pb levels stayed far below the EU limit value; and 7) concentrations of As, Ni and Hg were also far less than the reference values adopted by EU. In every location, Ni appeared more concentrated in PM2.5 than in coarser particles, and its levels were not that different from site to site, excluding the control. The highest As and Hg concentrations were found in the neighbourhood of the coal-fired, utility power plants. The results may be viewed as a “worst-case scenario” of atmospheric pollution, since they have been obtained in busy urban-industrial areas and/or near major power-generation and waste-incineration facilities.  相似文献   
993.
本文研究了不同土壤类型微量元素含量的差异,并对造成差异的因素进行了分析。 文中讨论了:1)京津唐地区土壤微量元素的背景含量;2)土壤微量元素含量与土壤类型的关系;3)土壤微量元素含量与水系的关系。  相似文献   
994.
稀土元素在水体食物链生物中迁移的摸拟研究   总被引:3,自引:1,他引:3  
王晓蓉  田笠卿 《环境化学》1993,12(3):212-218
本文用动态和静态摸拟系统分别研究了稀土元素在小球藻-大型溞-鲤鱼食物链生物上的迁移。结果表明:水生生物对稀土的生物积累作用有从水体直接摄取和从食物间接摄取两种方式,但稀土元素在该食物链上无生物放大作用,生物体中积累的稀土量和水环境中残余的稀土浓度从轻稀土向重稀土递减,稀土元素在水环境中迁移的最重要形式可能是物理-化学迁移。  相似文献   
995.
贵州省原煤中微量元素的组成特征   总被引:10,自引:0,他引:10  
倪建宇  冯新斌 《环境化学》1998,17(4):339-344
研究了贵州省各主要煤田中主要采煤层的As,B,Ba,Be,Cd,Co,Cr,C,Hg,Li,Ni,Pb,Sb,Se,Sr,Tl,V,Zn等微量元素的组成特征,贵州省原煤中微量元素的含量总体上的世界范围内的一致,但Sb,As,Hg等有害元素则明显富集,由于煤炭成因上的特殊性,其微量元素的组成除受煤植物的影响外,后期在煤作用对其有决定性的影响。  相似文献   
996.
采用盆栽方法研究了在镉、铅、锌污染土壤上,石灰和泥炭对小白菜生长状况及对污染元素(Cd,Pb,Zn)和养分元素(N,P,K,Cu,Mn,Fe)吸收的影响。结果表明,石灰消除了重金属的毒害症状.显著促进小白菜的生长、显著抑制小白菜对镉、铅、锌的吸收。石灰对氮、钾、铜、锰的吸收也有显著抑制作用。泥炭对小白菜生长的改善效果及对铜、铅、锌吸收的抑制效果较石灰差。提高酸性土壤pH值是减少作物对重金属吸收的有效方法。  相似文献   
997.
First results are presented from the Urban geochemistry of Tallinn, a project supported by the Scientific and Environmental Affairs Division of NATO. The distribution of chemical elements in 532 samples of the topsoils from the territory of the biggest industrial centre of Estonia (pop. 500,000) is interpreted. Statistical analysis and mapping of major and trace elements at the territory of the Tallinn region and of the city were performed and background values and local anomalies of chemical elements on the territory were determined. The investigation focussed on the determination of zones with anomalously high concentrations of elements and the relationships of soil contamination with different pollution sources. The increase of the element concentrations has natural as well as anthropogenic origins. A detailed comparative analysis of the element distributions and the results of a factor analysis showed that the distribution of the major chemical elements depended mainly on the composition of the underlying sedimentary rocks.The territory of Tallinn is characterised by relatively high and widespread concentrations of Ba, Cr, Ga, Ni, Ti and Zn. Especially intensive local concentrations were determined for As, Cr, Mn, Ni, Pb, S, V and Zn, which are typical for the local pollution of the soils by industrial sources. The levels of As, Cr, Mn and V are more than three times. Pb and Zn are more than five times higher in the geochemical anomalies than for background levels. For the Tallinn region two major associations of elements connected with industrial pollutions of the soil are typical: the first association includes Ba, Cr, Mn, Ni and partly Fe and the second one includes As, Pb and Zn. For the city of Tallinn an increase of Ag, Ba, Be, La, Pb, Sn and Zn concentration in the soil was detected. Ba, Cr, Mn and Ni occur in high concentrations in the soils around Maardu. Different types of contamination sources can be identified in Tallinn and its suburbs.  相似文献   
998.
Eight selected elements (As, Cd, Co, Cu, Pb, Zn, Cr and Ni) were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES) in five samples from the tailings pond (Zbiornik Gilow) and waste water stream (Zimmica) in the Kupferschiefer mining district in Southwest Poland. Waste water from mining and concentration plants was discharged into Zbiornik Gilow pond for 30 years before 1989. Below Zbiornik Gilow the water flows through Zimmica stream, and then discharges into the River Odra. The analytic results indicate that the contamination of As, Cd, Co, Cu, Pb and Zn has spread out over 5km, and the contamination by Ni and Cr extends for 1.5km along the Zimmica stream although the stream has been abandoned since 1989. These elements could still be toxic for plants, animals and humans. Polycyclic aromatic hydrocarbons (PAHs) were determined by GC and GC/MS. The results of the sediment samples show a contamination of PAHs only in trace contents.  相似文献   
999.
报道了乌鲁木齐市一年的内大气TSP中28种元素含量的监测结果,污染程度及变化规律,为进一步加强环境管理和大气污染治理,改善环境质量提供科学依据。  相似文献   
1000.
采用常规酸消化方法分解锑渣和铋渣固体废弃物试样.处理后的消解液直接用ICP—AES法同时测定了Cu、Ph、Mn、Cr、Ni、和Zn等多种重金属元素。方法的精密度和准确度较好,适合于常规固体环境样品的分析。  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