全文获取类型
收费全文 | 352篇 |
免费 | 6篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 13篇 |
废物处理 | 15篇 |
环保管理 | 67篇 |
综合类 | 50篇 |
基础理论 | 88篇 |
环境理论 | 2篇 |
污染及防治 | 88篇 |
评价与监测 | 21篇 |
社会与环境 | 9篇 |
灾害及防治 | 8篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 14篇 |
2016年 | 8篇 |
2015年 | 10篇 |
2014年 | 6篇 |
2013年 | 47篇 |
2012年 | 9篇 |
2011年 | 22篇 |
2010年 | 7篇 |
2009年 | 10篇 |
2008年 | 15篇 |
2007年 | 12篇 |
2006年 | 12篇 |
2005年 | 7篇 |
2004年 | 10篇 |
2003年 | 17篇 |
2002年 | 8篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1979年 | 7篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1968年 | 2篇 |
1961年 | 2篇 |
排序方式: 共有361条查询结果,搜索用时 15 毫秒
151.
Xinchuang Wang Guofan Shao Hua Chen Bernard J. Lewis Guang Qi Dapao Yu Li Zhou Limin Dai 《Environmental management》2013,52(3):612-620
Monitoring the dynamics of forest biomass at various spatial scales is important for better understanding the terrestrial carbon cycle as well as improving the effectiveness of forest policies and forest management activities. In this article, field data and Landsat image data acquired in 1999 and 2007 were utilized to quantify spatiotemporal changes of forest biomass for Dongsheng Forestry Farm in Changbai Mountain region of northeastern China. We found that Landsat TM band 4 and Difference Vegetation Index with a 3 × 3 window size were the best predictors associated with forest biomass estimations in the study area. The inverse regression model with Landsat TM band 4 predictor was found to be the best model. The total forest biomass in the study area decreased slightly from 2.77 × 106 Mg in 1999 to 2.73 × 106 Mg in 2007, which agreed closely with field-based model estimates. The area of forested land increased from 17.9 × 103 ha in 1999 to 18.1 × 103 ha in 2007. The stabilization of forest biomass and the slight increase of forested land occurred in the period following implementations of national forest policies in China in 1999. The pattern of changes in both forest biomass and biomass density was altered due to different management regimes adopted in light of those policies. This study reveals the usefulness of the remote sensing-based approach for detecting and monitoring quantitative changes in forest biomass at a landscape scale. 相似文献
152.
Management of microbial contamination in storm runoff from California coastal dairy pastures 总被引:1,自引:0,他引:1
Lewis DJ Atwill ER Lennox MS Pereira MD Miller WA Conrad PA Tate KW 《Journal of environmental quality》2010,39(5):1782-1789
A survey of storm runoff fecal coliform bacteria (FCB) from working farm and ranch pastures is presented in conjunction with a survey of FCB in manure management systems (MMS). The cross-sectional survey of pasture runoff was conducted on 34 pastures on five different dairies over 2 yr under varying conditions of precipitation, slope, manure management, and use of conservation practices such as vegetative filter strips. The MMS cross-sectional survey consisted of samples collected during 1 yr on nine different dairies from six loafing barns, nine primary lagoons, 12 secondary lagoons, and six irrigation sample points. Pasture runoff samples were additionally analyzed for Cryptosporidium sp. and Giardia duodenalis, whereby detectable concentrations occurred sporadically at higher FCB concentrations resulting in poor correlations with FCB. Prevalence of both parasites was lower relative to high-use areas studied simultaneously on these same farms. Application of manure to pastures more than 2 wk in advance of storm-associated runoff was related to a > or =80% reduction in FCB concentration and load compared to applications within 2 wk before a runoff event. For every 10 m of buffer length, a 24% reduction in FCB concentration was documented. A one-half (75%), one (90%), and two (99%) log10 reduction in manure FCB concentration was observed for manure holding times in MMS of approximately 20, 66, and 133 d, respectively. These results suggest that there are several management and conservation practices for working farms that may result in reduced FCB fluxes from agricultural operations. 相似文献
153.
Paul W. Mielke Charles F. Chappell Lewis O. Grant 《Journal of the American Water Resources Association》1972,8(6):1219-1224
Principal component analysis is used to investigate density requirements of wintertime orographic cloud seeding experiment precipitation sensor networks. Three passes in the vicinity of Climax, Colorado are studied. The eighteen or more evenly spaced precipitation sensors of each pass are almost completely described by three principal components. These three principal components appear to represent (i) mean precipitation, (ii) slope orientation to storm systems, and (iii) elevation. Evaluation of these principal components is implemented with two distribution-free tests, a proportionality test and the runs test. The results of this study suggest that the loss of experimental information caused by low density precipitation sensor networks may be of little consequence. 相似文献
154.
The Internet holds vast stores of information pertaining to pollution prevention and environmental issues, and with each day more is added. Yet, as this storehouse grows, the difficulty of finding specific information increases. This article details how EnviroDaemon was built to ease the task of finding this information and knowledge base. It automatically builds and updates a catalog of objects at pre-selected Internet sites that are related to pollution prevention. Users search for information by submitting keywords. Searches can be restricted to small subsets of the indexed sites by choosing one of five search criteria, or the entire catalog can be searched. The results are returned rapidly and are embedded in several lines of text to provide context. If the text looks promising, the user can click on a hyperlink to access the full article. Since its release in March, EnviroDaemon has seen increasing use, especially following its demonstration at the National Pollution Prevention Roundtable Conference. The authors also discuss the process of building this search engine to show interested readers how to create other environmental custom search engines. 相似文献
155.
The invertebrate benthic macrofauna of the northern part of the Gulf of St. Lawrence was sampled with a van Veen grab along a series of transects from 37 to 285 m in May, 1981. The pattern of spatial distribution was determined by classification and ordinastion techniques and by diversity and evenness statistics. Classification and ordination resulted in eleven station groups which could be divided into three broad faunal zones related to temperature, depth and sediment composition. The proportions of suspension feeders increased with sand content and nonselective deposit feeders increased with mud content. Faunal diversity decreased with depth. 相似文献
156.
K.?Donahoe L.?A.?Lewis S.?S.?SchneiderEmail author 《Behavioral ecology and sociobiology》2003,54(6):593-600
The function of the vibration signal of the honey bee (Apis mellifera) during house hunting was investigated by removing vibrating bees from swarms and examining the effects on waggle dancing for nest sites, liftoff preparations and swarm movement. We compared house hunting among three swarm types: (1) test swarms (from which vibrating bees were removed), (2) manipulated control (MC) swarms (from which randomly selected workers and some waggle dancers were removed), and (3) unmanipulated control (UC) swarms (from which no bees were removed). The removal of vibrating bees had pronounced effects on liftoff preparations and swarm movement. Compared to the MC and UC swarms, the test swarms had significantly greater liftoff-preparation periods, were more likely to abort liftoff attempts, and in some cases were unable to move to the chosen site after the swarm became airborne. However, the three swarm types did not differ in overall levels of waggle dance activity, the time required to achieve consensus for a nest site, the rate at which new waggle dancers were recruited for the chosen site, or the ability to maintain levels of worker piping necessary to prepare for flight. The removal of vibrating bees may therefore have altered liftoff behavior because of a direct effect on vibration signal activity. A primary function of the signal during house hunting may be to generate a level of activity in workers that enhances and coordinates responses to other signals that stimulate departure and movement to a new location.Communicated by R. Page 相似文献
157.
The operations of the heavy mineral sand mining industry in Australia are reviewed, with particular emphasis on the environmental aspects. Pre-mining environments, state and commonwealth legislative requirements, mining procedures and postmining rehabilitation and land use are described. The extraction of heavy minerals, principally rutile, zircon, ilmenite and monazite, is concentrated on the east coast between the Hawkesbury River in New South Wales and Rockhampton in Queensland; and on the west coast at Capel, south of Perth and at Eneabba, north of Perth. The industry, especially on the east coast, has suffered from conservationist and anti-mining movements during the 1970s because it operates on or near the coastline where the majority of Australians live or seek their recreation. This was less of a problem on the west coast because the deposits were inland. The future of the industry is good as long as a balance can be maintained between the interests of conservationists and the mining companies. 相似文献
158.
A method has been developed for concurrent analysis of C2-C7 hydrocarbons and C2-C5 oxygenated volatile organic compounds (o-VOCs) including alcohols, aldehydes, ketones and ethers. A multi-bed, Peltier-cooled adsorbent trap, consisting of Carboxen 1000 and Carbopack B, was used to acquire one sample per hour. Upon injection the sample was split in an approximately 50:50 ratio between a 50 m aluminium oxide (Al2O3) porous layer open tubular (PLOT) column and a 10 m LOWOX column. Eluents from each column were then analysed using flame ionisation detection (FID). Regular calibration of the system was performed using a standard cylinder mixture at the parts per billion by volume (ppbV) level for non-methane hydrocarbons (NMHCs) and a permeation tube method for the oxygenated species. The system is fully automated with NMHC detection limits between 1 and 10 parts per trillion by volume (pptV) and o-VOC detection limits between 10 and 40 pptV. 相似文献
159.
S.J. Moller J.D. Lee R. Commane P. Edwards D.E. Heard J. Hopkins T. Ingham A.S. Mahajan H. Oetjen J. Plane H. Roscoe A.C. Lewis L.J. Carpenter 《Atmospheric environment (Oxford, England : 1994)》2010,44(25):2971-2979
Measurements of NO and NO2 were made at a surface site (55.28 °N, 77.77 °W) near Kuujjuarapik, Canada during February and March 2008. NOx mixing ratios ranged from near zero to 350 pptv with emission from snow believed to be the dominant source. The amount of NOx was observed to be dependent on the terrain over which the airmass has passed before reaching the measurement site. The 24 h average NOx emission rates necessary to reproduce observations were calculated using a zero-dimensional box model giving rates ranging from 6.9 × 108 molecule cm?2 s?1 to 1.2 × 109 molecule cm?2 s?1 for trajectories over land and from 3.8 × 108 molecule cm?2 s?1 to 6.6 × 108 molecule cm?2 s?1 for trajectories over sea ice. These emissions are higher than those suggested by previous studies and indicate the importance of lower latitude snowpack emissions. The difference in emission rate for the two types of snow cover shows the importance of snow depth and underlying surface type for the emission potential of snow-covered areas. 相似文献
160.