全文获取类型
收费全文 | 417篇 |
免费 | 20篇 |
国内免费 | 103篇 |
专业分类
安全科学 | 71篇 |
废物处理 | 20篇 |
环保管理 | 69篇 |
综合类 | 209篇 |
基础理论 | 65篇 |
污染及防治 | 63篇 |
评价与监测 | 33篇 |
社会与环境 | 9篇 |
灾害及防治 | 1篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 16篇 |
2020年 | 13篇 |
2019年 | 4篇 |
2018年 | 7篇 |
2017年 | 3篇 |
2016年 | 11篇 |
2015年 | 16篇 |
2014年 | 9篇 |
2013年 | 22篇 |
2012年 | 19篇 |
2011年 | 18篇 |
2010年 | 15篇 |
2009年 | 15篇 |
2008年 | 19篇 |
2007年 | 41篇 |
2006年 | 28篇 |
2005年 | 31篇 |
2004年 | 23篇 |
2003年 | 31篇 |
2002年 | 29篇 |
2001年 | 18篇 |
2000年 | 27篇 |
1999年 | 18篇 |
1998年 | 19篇 |
1997年 | 15篇 |
1996年 | 6篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有540条查询结果,搜索用时 125 毫秒
481.
Ammonia in the environment: from ancient times to the present 总被引:3,自引:0,他引:3
Sutton MA Erisman JW Dentener F Möller D 《Environmental pollution (Barking, Essex : 1987)》2008,156(3):583-604
Recent research on atmospheric ammonia has made good progress in quantifying sources/sinks and environmental impacts. This paper reviews the achievements and places them in their historical context. It considers the role of ammonia in the development of agricultural science and air chemistry, showing how these arose out of foundations in 18th century chemistry and medieval alchemy, and then identifies the original environmental sources from which the ancients obtained ammonia. Ammonia is revealed as a compound of key human interest through the centuries, with a central role played by sal ammoniac in alchemy and the emergence of modern science. The review highlights how recent environmental research has emphasized volatilization sources of ammonia. Conversely, the historical records emphasize the role of high-temperature sources, including dung burning, coal burning, naturally burning coal seams and volcanoes. Present estimates of ammonia emissions from these sources are based on few measurements, which should be a future priority. 相似文献
482.
483.
484.
介绍了绿色化学的原理、研究现状,总结了绿色化学技术的应用进展.从大气污染、水污染和固体废物3方面论述了绿色化学技术在环境污染治理中的应用情况,并提出应用绿色化学技术来解决环境污染问题是环境保护的发展方向. 相似文献
485.
486.
Zhi‐Jun Liu Donald E. Weller David L. Correll Thomas E. Jordan 《Journal of the American Water Resources Association》2000,36(6):1349-1365
ABSTRACT: We measured the base‐flow stream chemistry in all the major physiographic provinces of the Chesapeake Bay drainage basin. The spatial variation of stream chemistry was closely related to differences in geology and land cover among the sampled watersheds. Some stream chemistry variables were strongly affected by geological settings in the watersheds while others were more influenced by land cover. The effects of land cover differed among chemical constituents and regions. Concentrations of Ca2+, Mg2+, pH, total alkalinity, and conductivity were mainly functions of carbonate bedrock, especially in the Great Valley. Nitrate‐N and total dissolved N were closely related to cropland and increased as the percentage of cropland increased. The rate of increase varied from region to region with the highest in the Piedmont. Na+ and Cl? were mainly affected by the percentage of developed area in a watershed, especially in the Coastal Plain and Piedmont. We observed no significant effects of region or land cover on species of phosphorus because samples were collected under base flow conditions and only dissolved forms were measured. Dissolved silicate (DSi) was not related to any other water chemistry variables. DSi increased as developed area decreased and cropland increased in the Coastal Plain, but these patterns were reversed in the Piedmont. There was no consistent pattern in the spatial variation of land cover effects on the reduced forms of N, dissolved organic P, dissolved organic matter, and K+. 相似文献
487.
电生成羟基自由基及其对染料降解脱色的研究 总被引:8,自引:0,他引:8
以电化学循环伏安法和红外光谱分析 (IR) ,研究了茜素红及酸性铬蓝在电解槽中处理前后的电化学行为的变化 ,进一步阐明Fenton试剂的作用机制。电解生成的过氧化氢与阳极溶解的Fe2+ 进行随后反应 ,生成羟基自由基 (Fenton试剂 ) ,进而对有机染料进行氧化反应 ,使其不饱和的—N=N—双键断裂 ,分解成萘胺与氨基苯酚磺酸两个部分 ,从而达到有机染料降解、脱色的效果。测试结果表明 ,电解处理15min内 ,脱色率和CODcr的去除率变化较大 ,电解处理 1h ,CODcr的去除率达 80 % ,脱色率达 98%. 相似文献
488.
ABSTRACT Mass budgets for chloride were estimated from 1975-1978 for the Mississippi River from headwaters to near the mouth to determine the magnitudes of natural and anthropogenic sources. Annual chloride input from precipitation ranged from about 200 kg mi-2yr-1 at Royalton, Minnesota, to about 350 kg mi-2yr-1 at Vicksburg, Mississippi. Mass export ranged from about 900 kg mi-2yr-1 at Royalton to about 8000 kg mi-2yr-1 at Vicksburg. As much as 80 percent of the residual, the difference between input and export, probably is contributed by anthropogenic sources. In particular, semi-logarithmic scatterplots of monthly total discharge against chloride concentration show that, during early spring, chloride elevations in the Mississippi River and Ohio River are elevated, possibly because of flushing of road salt and leaching of chloride from the accumulated snowpack. 相似文献
489.
Bahram Momen Larry W. Eichler Charles W. Boylen Jonathan P. Zehr 《Environmental management》1997,21(5):725-732
a (Chl a), silica (Si), and chloride (Cl) through the use of proper statistical techniques. Results indicate no statistically significant
changes in the concentrations of TP, Chl a, or Si in the spring or summer from 1981 to 1993. A significant temporal trend of increase in Cl concentration is, however,
detected. This is perhaps the strongest evidence that the development of the Lake George watershed has affected lakewater
chemistry. In spring, the concentrations of TP, Chl a, Si, and Cl, averaged over all 13 years, were higher in the south basin, but differences are not statistically significant
(i.e., P > 0.05). In summer, Si was slightly but significantly lower, and Cl was nonsignificantly higher in the south basin. Significant
interactions between temporal and spatial changes are detected based only on summer values of TP and Chl a, indicating differential trends of change for these two variables in the south and north basins during the last 13 years. 相似文献
490.
Robert L. Edmonds Roger D. Blew 《Journal of the American Water Resources Association》1997,33(4):781-793
ABSTRACT: Human induced long-term changes in precipitation and stream chemistry have been observed in eastern North America and Europe, but few long-term studies have been conducted in coastal western North America. The objectives of this research were to determine: (1) time trends in precipitation and stream chemistry in a pristine old-growth forest watershed, and (2) seasonal patterns in precipitation and stream chemistry. It was conducted in 58 ha West Twin Creek Watershed, Hoh River Valley, Olympic National Park, Washington from 1984 to 1993. Vegetation consists of old-growth forest, with western hemlock, Douglas-fir, western redcedar, Pacific silver fir, and Sitka spruce being the dominant tree species. Annual precipitation varied from 2336 to 4518 mm during the study period with the majority of the rain falling between October and May. Chemistry of precipitation was strongly dominated by oceanic influences with Na and Cl being the dominant ions. The chemistry of the stream was influenced by bedrock weathering and was dominated by Ca, HCO3, and SO4 and was not strongly related to precipitation chemistry. The pH of precipitation averaged 5.3 over time and ranged from 4.3 to 7.1, while the stream pH averaged 7.5 and ranged from 5.5 to 9.0. There were few long-term trends in the chemical constituents of bulk precipitation or stream water with the exception of a slight decrease in NO3 in precipitation and an increase of SO4 in stream water. A trend of decreasing concentrations of Ca, Mg and Na in precipitation also occurred. There were no significant seasonal patterns in precipitation although the highest SO4 concentrations usually occurred in late spring and summer perhaps due marine algal activity. Strong seasonal trends occurred in concentrations of HCO3, SO4, Ca, Mg, and Na in stream water resulting from weathering and stream flow patterns, with highest ion concentrations occurring just before the onset of the rainy season. Pulses of NO3 in the stream were observed during fall and early winter resulting from the release of NO3 which had accumulated in soils or sediments. 相似文献