全文获取类型
收费全文 | 14571篇 |
免费 | 987篇 |
国内免费 | 3091篇 |
专业分类
安全科学 | 878篇 |
废物处理 | 254篇 |
环保管理 | 4182篇 |
综合类 | 8299篇 |
基础理论 | 1491篇 |
环境理论 | 1篇 |
污染及防治 | 1124篇 |
评价与监测 | 1219篇 |
社会与环境 | 978篇 |
灾害及防治 | 223篇 |
出版年
2024年 | 48篇 |
2023年 | 193篇 |
2022年 | 333篇 |
2021年 | 352篇 |
2020年 | 426篇 |
2019年 | 352篇 |
2018年 | 330篇 |
2017年 | 500篇 |
2016年 | 624篇 |
2015年 | 708篇 |
2014年 | 688篇 |
2013年 | 1041篇 |
2012年 | 1059篇 |
2011年 | 1173篇 |
2010年 | 816篇 |
2009年 | 817篇 |
2008年 | 618篇 |
2007年 | 1024篇 |
2006年 | 977篇 |
2005年 | 752篇 |
2004年 | 659篇 |
2003年 | 654篇 |
2002年 | 580篇 |
2001年 | 464篇 |
2000年 | 450篇 |
1999年 | 385篇 |
1998年 | 262篇 |
1997年 | 255篇 |
1996年 | 235篇 |
1995年 | 204篇 |
1994年 | 183篇 |
1993年 | 169篇 |
1992年 | 123篇 |
1991年 | 97篇 |
1990年 | 81篇 |
1989年 | 81篇 |
1988年 | 73篇 |
1987年 | 68篇 |
1986年 | 43篇 |
1984年 | 46篇 |
1983年 | 56篇 |
1982年 | 58篇 |
1981年 | 73篇 |
1980年 | 79篇 |
1979年 | 72篇 |
1978年 | 50篇 |
1977年 | 47篇 |
1973年 | 44篇 |
1972年 | 38篇 |
1971年 | 58篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
81.
Thomas W. May Michael J. Walther Jimmie D. Petty James F. Fairchild Jeff Lucero Mike Delvaux Jill Manring Mike Armbruster David Hartman 《Environmental monitoring and assessment》2001,72(2):179-206
The Republican River Basin of Colorado,Nebraska, and Kansas lies in a valley which contains PierreShale as part of its geological substrata. Selenium is anindigenous constituent in the shale and is readily leached intosurrounding groundwater. The Basin is heavily irrigated throughthe pumping of groundwater, some of which is selenium-contaminated, onto fields in agricultural production. Water,sediment, benthic invertebrates, and/or fish were collected from46 sites in the Basin and were analyzed for selenium to determinethe potential for food-chain bioaccumulation, dietary toxicity,and reproductive effects of selenium in biota. Resultingselenium concentrations were compared to published guidelines orbiological effects thresholds. Water from 38% of the sites (n = 18) contained selenium concentrations exceeding 5 g L-1, which is reported to be a high hazard for selenium accumulation into the planktonic food chain. An additional 12 sites (26% of the sites) contained selenium in water between 3–5 g L-1, constituting a moderate hazard. Selenium concentrations in sedimentindicated little to no hazard for selenium accumulation fromsediments into the benthic food chain. Ninety-five percent ofbenthic invertebrates collected exhibited selenium concentrationsexceeding 3 g g-1, a level reported as potentially lethal to fish and birds that consume them. Seventy-five percent of fish collected in 1997, 90% in 1998, and 64% in 1999 exceeded 4 g g-1selenium, indicating a high potential for toxicity andreproductive effects. However, examination of weight profilesof various species of collected individual fish suggestedsuccessful recruitment in spite of selenium concentrations thatexceeded published biological effects thresholds for health andreproductive success. This finding suggested that universalapplication of published guidelines for selenium may beinappropriate or at least may need refinement for systems similarto the Republican River Basin. Additional research is needed todetermine the true impact of selenium on fish and wildliferesources in the Basin. 相似文献
82.
Osowski SL Swick JD Carney GR Pena HB Danielson JE Parrish DA 《Environmental monitoring and assessment》2001,66(2):159-185
Swine Concentrated Animal Feeding Operations (CAFOs) have received much attention in recent years. As a result, a watershed-based screening tool, the Cumulative Risk Index Analysis (CRIA), was developed to assess the cumulative impacts of multiple CAFO facilities in a watershedsubunit. The CRIA formula calculates an index number based on: 1) the area of one or more facilities compared to the area of the watershed subunit, 2) the average of the environmental vulnerability criteria, and 3) the average of the industry-specific impact criteria. Each vulnerability or impact criterion is ranked on a 1 to 5 scale, with a low rank indicating low environmental vulnerability or impact and a high rank indicating high environmental vulnerability or impact. The individual criterion ranks, as well as the total CRIA score, can be used to focus the environmental analysis and facilitate discussions with industry, public, and other stakeholders in the Agency decision-making process. 相似文献
83.
Paul Pinsky Matthew Lorber Kent Johnson Burton Kross Leon Burmeister Amina Wilkins George Hallberg 《Environmental monitoring and assessment》1997,47(2):197-221
In 1988, the Iowa Department of Natural Resources, along withthe University of Iowa, conducted the Statewide Rural WellWater Survey, commonly known as SWRL. A total of 686private rural drinking water wells was selected by use of aprobability sample and tested for pesticides and nitrate. A subsetof these wells, the 10% repeat wells, were additionally sampledin October, 1990 and June, 1991. Starting in November, 1991,the University of Iowa, with sponsorship from the United StatesEnvironmental Protection Agency, revisited the 10% repeat wellsto begin a study of the temporal variability of atrazine and nitratein wells. Other wells, which had originally tested positive foratrazine in SWRL but were not in the 10% population, wereadded to the study population. Temporal sampling for a year-long period began in February of 1992 and concluded in Januaryof 1993. All wells were sampled monthly, a subset was sampledweekly, and a second subset was sampled for 14 day consecutiveperiods. Of the 67 wells in the 10% population tested monthly,7 (10.4%) tested positive for atrazine at least once during theyear, and 3 (4%) were positive each of the 12 months. Theaverage concentration in the 7 wells was 0.10 µg/L. Fornitrate, 15 (22%) wells in the 10% repeat population monthlysampling were above the Maximum Contaminant Level of 10 mg/L at least once. This paper, the second of two papers on thisstudy, describes the analysis of data from the survey. The firstpaper (Lorber et al., 1997) reviews the study design, theanalytical methodologies, and development of the data base. 相似文献
84.
85.
86.
北京市地表水环境面临的主要问题及防治对策 总被引:6,自引:2,他引:6
针对北京市地表水水质污染现状、污染特点及其变化趋势,深入剖析了目前地表水环境及其治理过程中存在的主要问题,提出进一步改善北京市地表水环境的措施与建议。 相似文献
87.
88.
博斯腾湖水质矿化度模型及预测研究 总被引:6,自引:0,他引:6
根据博斯腾湖1985~1995年水质监测数据和出入湖水量等水文数据观测值,采用水质扩散模型和盐量平衡关系推导出博斯腾湖大湖区(简称博湖)水质矿化度模型,并预测了几种情况下博湖水质矿化度及近几年变化趋势,分析了影响博湖水质矿化度的主要因素,为博湖的近期和远期环境保护规划、环境管理等提供科学依据. 相似文献
89.
以邢台市环境保护监测站10年来的监测资料为依据,运用单因子比值法,环比发展速率外推法和直线回归法,对地下水环境质量现状及10年的动态变化进行了分析,研究和评述,并对发展趋势做了预测性评价。 相似文献
90.
对色泽较深,含杂质量较高的废水加硅油I以抑制测定中蒸馏产生的泡沫.结果表明,在250ml水样中加硅油IO.10~1.25ml,即可收到理想效果.硅油I性质稳定,不随水蒸汽蒸出,对测定无干扰. 相似文献