全文获取类型
收费全文 | 2137篇 |
免费 | 62篇 |
国内免费 | 24篇 |
专业分类
安全科学 | 137篇 |
废物处理 | 95篇 |
环保管理 | 492篇 |
综合类 | 227篇 |
基础理论 | 563篇 |
环境理论 | 3篇 |
污染及防治 | 452篇 |
评价与监测 | 134篇 |
社会与环境 | 86篇 |
灾害及防治 | 34篇 |
出版年
2023年 | 17篇 |
2022年 | 27篇 |
2021年 | 26篇 |
2020年 | 28篇 |
2019年 | 26篇 |
2018年 | 55篇 |
2017年 | 71篇 |
2016年 | 75篇 |
2015年 | 75篇 |
2014年 | 66篇 |
2013年 | 166篇 |
2012年 | 96篇 |
2011年 | 172篇 |
2010年 | 111篇 |
2009年 | 94篇 |
2008年 | 127篇 |
2007年 | 136篇 |
2006年 | 133篇 |
2005年 | 78篇 |
2004年 | 76篇 |
2003年 | 76篇 |
2002年 | 63篇 |
2001年 | 45篇 |
2000年 | 31篇 |
1999年 | 34篇 |
1998年 | 28篇 |
1997年 | 22篇 |
1996年 | 30篇 |
1995年 | 20篇 |
1994年 | 21篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 12篇 |
1990年 | 15篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1987年 | 18篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 13篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1969年 | 3篇 |
1966年 | 3篇 |
1936年 | 2篇 |
1935年 | 3篇 |
1926年 | 2篇 |
排序方式: 共有2223条查询结果,搜索用时 31 毫秒
101.
Santamaría J Brusseau ML Araujo J Orosz-Coghlan P Blanford WJ Gerba CP 《Journal of environmental quality》2012,41(4):1246-1252
A series of miscible-displacement experiments was conducted to examine the retention and transport behavior of oocysts in natural porous media. Three soils and a model sand were used that differed in physical and geochemical properties. Transport behavior was examined under various treatment conditions to help evaluate retention mechanisms. Significant retention of oocysts was observed for all media despite the fact that conditions were unfavorable for physicochemical interactions with respect to DLVO theory. The magnitude of retention was not influenced significantly by alterations in solution chemistry (reduction in ionic strength) or soil surface properties (removal of soil organic matter and metal oxides). On the basis of the observed results, it appears that retention by secondary energy minima or geochemical microdomains was minimal for these systems. The porous media used for the experiments exhibited large magnitudes of surface roughness, and it is suggested that this surface roughness contributed significantly to oocyst retention. 相似文献
102.
Rebecca L. Phillips Moffatt K. Ngugi John Hendrickson Aaron Smith Mark West 《Environmental management》2012,50(5):914-928
Managers of the nearly 0.5 million ha of public lands in North and South Dakota, USA rely heavily on manual measurements of canopy height in autumn to ensure conservation of grassland structure for wildlife and forage for livestock. However, more comprehensive assessment of vegetation structure could be achieved for mixed-grass prairie by integrating field survey, topographic position (summit, mid and toeslope) and spectral reflectance data. Thus, we examined the variation of mixed-grass prairie structural attributes (canopy leaf area, standing crop mass, canopy height, nitrogen, and water content) and spectral vegetation indices (VIs) with variation in topographic position at the Grand River National Grassland (GRNG), South Dakota. We conducted the study on a 36,000-ha herbaceous area within the GRNG, where randomly selected plots (1?km2 in size) were geolocated and included summit, mid and toeslope positions. We tested for effects of topographic position on measured vegetation attributes and VIs calculated from Landsat TM and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data collected in July 2010. Leaf area, standing crop mass, canopy height, nitrogen, and water content were lower at summits than at toeslopes. The simple ratio of Landsat Band 7/Band 1 (SR71) was the VI most highly correlated with canopy standing crop and height at plot and landscape scales. Results suggest field and remote sensing-based grassland assessment techniques could more comprehensively target low structure areas at minimal expense by layering modeled imagery over a landscape stratified into topographic position groups. 相似文献
103.
104.
Saini M Taggart MA Knopp D Upreti S Swarup D Das A Gupta PK Niessner R Prakash V Mateo R Cuthbert RJ 《Environmental pollution (Barking, Essex : 1987)》2012,160(1):11-16
Diclofenac, a non-steroidal anti-inflammatory drug (NSAID), has caused catastrophic vulture declines across the Indian sub-continent. Here, an indirect ELISA is used to detect and quantify diclofenac in 1251 liver samples from livestock carcasses collected across India between August 2007 and June 2008, one to two years after a ban on diclofenac manufacture and distribution for veterinary use was implemented. The ELISAs applicability was authenticated with independent data obtained using LC-ESI/MS. Of 1251 samples, 1150 (91.9%) were negative for diclofenac using both methods, and 60 (4.8%) were positive at 10-4348 and 10-4441 μg kg(-1) when analysed by ELISA and LC-ESI/MS, respectively. The residue level relationship in the 60 positive samples was highly significant (p < 0.001, r(2) = 0.644). Data suggest that this immunological assay could be used not only for cost effective sample screening, but also for residue level semi-quantification. 相似文献
105.
Occurrence of glyphosate and acidic herbicides in select urban rivers and streams in Canada, 2007 总被引:2,自引:1,他引:1
106.
Hixson M Mahmud A Hu J Kleeman MJ 《Journal of the Air & Waste Management Association (1995)》2012,62(5):566-575
The effectiveness of emissions control programs designed to reduce concentrations of airborne particulate matter with an aerodynamic diameter < 2.5 microm (PM2.5) in California's San Joaquin Valley was studied in the year 2030 under three growth scenarios: low, medium, and high population density. Base-case inventories for each choice of population density were created using a coupled emissions modeling system that simultaneously considered interactions between land use and transportation, area source, and point source emissions. The ambient PM2.5 response to each combination of population density and emissions control was evaluated using a regional chemical transport model over a 3-week winter stagnation episode. Comparisons between scenarios were based on regional average and population-weighted PM2.5 concentrations. In the absence of any emissions control program, population-weighted concentrations of PM2.5 in the future San Joaquin Valley are lowest undergrowth scenarios that emphasize low population density. A complete ban on wood burning and a 90% reduction in emissions from food cooking operations and diesel engines must occur before medium- to high-density growth scenarios result in lower population-weighted concentrations of PM2.5. These trends partly reflect the fact that existing downtown urban cores that naturally act as anchor points for new high-density growth in the San Joaquin Valley are located close to major transportation corridors for goods movement. Adding growth buffers around transportation corridors had little impact in the current analysis, since the 8-km resolution of the chemical transport model already provided an artificial buffer around major emissions sources. Assuming that future emissions controls will greatly reduce or eliminate emissions from residential wood burning, food cooking, and diesel engines, the 2030 growth scenario using "as-planned" (medium) population density achieves the lowest population-weighted average PM2.5 concentration in the future San Joaquin Valley during a severe winter stagnation event. Implications: The San Joaquin Valley is one of the most heavily polluted air basins in the United States that are projected to experience strong population growth in the coming decades. The best plan to improve air quality in the region combines medium- or high-density population growth with rigorous emissions controls. In the absences of controls, high-density growth leads to increased population exposure to PM2.5 compared with low-density growth scenarios (urban sprawl). 相似文献
107.
Electrical resistance heating (ERH) has become a common method of remediation for volatile organic compounds (VOCs) in unconsolidated soils, both above and below the water table. Recently, use of ERH has expanded to include treatment of contaminated sedimentary bedrock. This article describes the implementation issues for rock remediation and provides case studies of three sites remediated by ERH in Maryland, New Jersey, and Indiana. With proper design, remediation of bedrock can be as effectively completed as remediation of overburden materials. © 2010 Wiley Periodicals, Inc. 相似文献
108.
Humans can dive with critically endangered grey nurse sharks (Carcharias taurus) along the east coast of Australia. This study investigated both compliance of tourist divers to a code of conduct and legislation
and the behaviour of grey nurse sharks in the presence of divers. A total of 25 data collection dives were conducted from
December 2008 to January 2009. Grey nurse shark and diver behaviour were documented using 2-min scan samples and continuous
observation. The proportion of time spent observing human–shark interactions was 9.4% of total field time and mean human–shark
interaction time was 15.0 min. Results were used to gauge the effectiveness of current management practices for the grey nurse
shark dive industry at Fish Rock in New South Wales, Australia. Grey nurse shark dive tourists were compliant to stipulations
in the code of conduct and legislation (compliance ranged from 88 to 100%). The research detailed factors that may promote
compliance in wildlife tourism operations such as the clarity of the stipulations, locality of the target species and diver
perceptions of sharks. Results indicated that grey nurse sharks spent the majority of their time milling (85%) followed by
active swimming (15%). Milling behaviour significantly decreased in the presence of more than six divers. Distance between
sharks and divers, interaction time and number of sharks were not significantly correlated with grey nurse shark school behaviour.
Jaw gaping, rapid withdrawal and stiff or jerky movement were the specific behaviours of grey nurse sharks that occurred most
frequently and were associated with distance between divers and sharks and the presence of six or more divers. Revision of
the number of divers allowed per interaction with a school of grey nurse sharks and further research on the potential impacts
that shark-diving tourism may pose to grey nurse sharks is recommended. 相似文献
109.
Zhou X Helmers MJ Asbjornsen H Kolka R Tomer MD 《Journal of environmental quality》2010,39(6):2006-2015
Many croplands planted to perennial grasses under the Conservation Reserve Program are being returned to crop production, and with potential consequences for water quality. The objective of this study was to quantify the impact of grassland-to-cropland conversion on nitrate-nitrogen (NO3-N) concentrations in soil and shallow groundwater and to assess the potential for perennial filter strips (PFS) to mitigate increases in NO3-N levels. The study, conducted at the Neal Smith National Wildlife Refuge (NSNWR) in central Iowa, consisted of a balanced incomplete block design with 12 watersheds and four watershed-scale treatments having different proportions and topographic positions of PFS planted in native prairie grasses: 100% rowcrop, 10% PFS (toeslope position), 10% PFS (distributed on toe and as contour strips), and 20 PFS (distributed on toe and as contour strips). All treatments were established in fall 2006 on watersheds that were under bromegrass (Bromus L.) cover for at least 10 yr. Nonperennial areas were maintained under a no-till 2-yr corn (Zea mays L.)--soybean [Glycine max. (L.) Merr.] rotation since spring 2007. Suction lysimeter and shallow groundwater wells located at upslope and toeslope positions were sampled monthly during the growing season to determine NO3-N concentration from 2005 to 2008. The results indicated significant increases in NO3-N concentration in soil and groundwater following grassland-to-cropland conversion. Nitrate-nitrogen levels in the vadose zone and groundwater under PFS were lower compared with 100% cropland, with the most significant differences occurring at the toeslope position. During the years following conversion, PFS mitigated increases in subsurface nitrate, but long-term monitoring is needed to observe and understand the full response to land-use conversion. 相似文献
110.
Erica Donner Kris Broos Diane Heemsbergen Mike J. McLaughlin Mark E. Hodson 《Environmental pollution (Barking, Essex : 1987)》2010,158(1):339-345
As zinc (Zn) is both an essential trace element and potential toxicant, the effects of Zn fixation in soil are of practical significance. Soil samples from four field sites amended with ZnSO4 were used to investigate ageing of soluble Zn under field conditions over a 2-year period. Lability of Zn measured using 65Zn radioisotope dilution showed a significant decrease over time and hence evidence of Zn fixation in three of the four soils. However, 0.01 M CaCl2 extractions and toxicity measurements using a genetically modified lux-marked bacterial biosensor did not indicate a decrease in soluble/bioavailable Zn over time. This was attributed to the strong regulatory effect of abiotic properties such as pH on these latter measurements. These results also showed that Zn ageing occurred immediately after Zn spiking, emphasising the need to incubate freshly spiked soils before ecotoxicity assessments. 相似文献