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   93篇
  免费   1篇
安全科学   7篇
废物处理   12篇
环保管理   21篇
综合类   9篇
基础理论   12篇
污染及防治   24篇
评价与监测   9篇
  2021年   2篇
  2020年   1篇
  2019年   3篇
  2018年   1篇
  2017年   9篇
  2016年   2篇
  2014年   2篇
  2013年   4篇
  2012年   1篇
  2011年   6篇
  2010年   2篇
  2009年   5篇
  2008年   7篇
  2007年   5篇
  2006年   12篇
  2005年   2篇
  2004年   3篇
  2003年   8篇
  2001年   2篇
  2000年   3篇
  1999年   3篇
  1998年   3篇
  1992年   1篇
  1991年   1篇
  1989年   1篇
  1988年   1篇
  1986年   2篇
  1969年   1篇
  1968年   1篇
排序方式: 共有94条查询结果,搜索用时 234 毫秒
31.
We investigated air temperature and pressure gradients and their trends for the period 1996–2014 in Greenland and compared these to other periods since 1958. Both latitudinal temperature and pressure gradients were strongest during winter. An overall temperature increase up to 0.15 °C year?1 was observed for 1996–2014. The strongest warming happened during February at the West coast (up to 0.6 °C year?1), weaker but consistent and significant warming occurred during summer months (up to 0.3 °C year?1) both in West and East Greenland. Pressure trends on a monthly basis were mainly negative, but largely statistically non-significant. Compared with other time windows in the past six decades, the period 1996–2014 yielded an above-average warming trend. Northeast Greenland and the area around Zackenberg follow the general pattern but are on the lower boundary of observed significant trends in Greenland. We conclude that temperature-driven ecosystem changes as observed in Zackenberg may well be exceeded in other areas of Greenland.  相似文献   
32.
In organic philosophy, the concept of “naturalness” is of major importance. According to the organic interpretation of animal welfare, natural living is considered a precondition for accomplishing welfare and the principal aims of organic production include the provision of natural living conditions for animals. However, respective regulations are lacking in organic legislation. In practice, the life of a calf in organic rearing systems can deviate from being natural, since common practices in dairy farms include early weaning, dehorning, or cow-calf separation soon after birth. This case study explores how calf welfare is approached in six different organic dairy farms and how far the concept of naturalness is implemented. The farms included in this study were located in Norway and Sweden. A semi-structured questionnaire was used for data collection. The interviewed farmers approach the concept of welfare in various ways and state that “naturalness” is an aspect of animal welfare. However, in practice in the calf rearing systems under study, only a few “naturalness” aspects were implemented. Reasons for the observed discrepancy might lie in differing understandings of “naturalness,” in economic restrictions, and in other trade-offs resulting from production system inherent characteristics and in limited regulation concerning provision of natural living aspects.  相似文献   
33.
A new robust method for determination of hydrocarbons in water without use of Freon or other halogenated solvents has been validated and subjected to an interlaboratory exercise. The method is based on extraction with a light hydrocarbon (boiling point in the 39–69°C range), followed by cleanup for removal of polar components and detection by gas chromatography (GC) with flame ionisation (FID) detection. The performance characteristics of the method are comparable with that of the previous Freon-IR method with recoveries in the 60–80% range and reproducibility (between laboratory variations) of about 30%.

A screening method for hydrocarbons in the range 5 ppm and above based on infrared spectroscopy (IR), and a promising method for detection of low levels based on solid phase extraction (SPE) has been tested and validated.  相似文献   

34.
Most species face multiple anthropogenic disruptions. Few studies have quantified the cumulative influence of multiple threats on species of conservation concern, and far fewer have quantified the potential relative value of multiple conservation interventions in light of these threats. We linked spatial distribution and population viability models to explore conservation interventions under projected climate change, urbanization, and changes in fire regime on a long‐lived obligate seeding plant species sensitive to high fire frequencies, a dominant plant functional type in many fire‐prone ecosystems, including the biodiversity hotspots of Mediterranean‐type ecosystems. First, we investigated the relative risk of population decline for plant populations in landscapes with and without land protection under an existing habitat conservation plan. Second, we modeled the effectiveness of relocating both seedlings and seeds from a large patch with predicted declines in habitat area to 2 unoccupied recipient patches with increasing habitat area under 2 projected climate change scenarios. Finally, we modeled 8 fire return intervals (FRIs) approximating the outcomes of different management strategies that effectively control fire frequency. Invariably, long‐lived obligate seeding populations remained viable only when FRIs were maintained at or above a minimum level. Land conservation and seedling relocation efforts lessened the impact of climate change and land‐use change on obligate seeding populations to differing degrees depending on the climate change scenario, but neither of these efforts was as generally effective as frequent translocation of seeds. While none of the modeled strategies fully compensated for the effects of land‐use and climate change, an integrative approach managing multiple threats may diminish population declines for species in complex landscapes. Conservation plans designed to mitigate the impacts of a single threat are likely to fail if additional threats are ignored. Manejo de Incendios, Reubicación Administrada y Opciones de Conservación de Suelo para Plantas de Vida Larga con Sembrado Obligado bajo los Cambios Globales en el Clima, la Urbanización y el Régimen de Incendios  相似文献   
35.
36.
P.O Darnerud     Bergman  B.O Lund  I Brandt 《Chemosphere》1989,18(9-10):1821-1827
Three 14C-labelled polychloroalkanes (C12 and C16), representing low (23% Cl by weight), medium (51%), and highly (68%) chlorinated paraffin (CP) mixtures, were presented to rainbow trout via the water. The uptake in fat-rich tissues was positively correlated to the degree of chlorination of the preparations. Notably, all preparations gave rise to a high and selective uptake of radioactivity in the olfactory organ and gills. This selective radiolabelling may reflect a general ability of these organs to enrich xenobiotics from the surrounding water. The olfactory organ may be a hitherto unforseen target for toxic environmental pollutants in fish.  相似文献   
37.
Meteorological dispersion modeling and pine trees used as "integrating monitors" were used to consider the probable source of a phytotoxic pollutant producing symptoms previously un-reported in the literature. Two sources, a chemical plant (A) and a fabric finishing plant (B) north of Raleigh, NC, were considered using the Air Quality Display Model (AQDM). Using the ability of this model to accommodate extra receptors corresponding to "monitoring" sites, we found good correlation between observed injury and predicted relative concentrations due to assumed emissions from source A. The poor agreement between predicted and observed injury if source B alone were modeled (or both sources together) suggested that source A alone emitted the causal agent.  相似文献   
38.
Triclosan is an antimicrobial agent which is widely used in household and personal care products. Widespread use of this compound has led to the elevated concentrations of triclosan in wastewater, wastewater treatment plants (WWTPs) and receiving waters. Removal of triclosan and formation of triclosan-methyl was investigated in activated sludge from a standard activated sludge WWTP equipped with enhanced biological phosphorus removal. The removal was found to occur mainly under aerobic conditions while under anoxic (nitrate reducing) and anaerobic conditions rather low removal rates were determined. In a laboratory-scale activated sludge reactor 75% of the triclosan was removed under aerobic conditions within 150 h, while no removal was observed under anaerobic or anoxic conditions. One percent of the triclosan was converted to triclosan-methyl under aerobic conditions, less under anoxic (nitrate reducing) and none under anaerobic conditions.  相似文献   
39.
40.
A microbial consortia consisting of three bacteria isolated from tanning and textile wastewaters revealed high capacity to simultaneously bioaccumulate dye and Cr(VI). The identity of the bacteria were determined by 16S rRNA gene analysis to be closely related to Ochrobactrium sp., Salmonella enterica and Pseudomonas aeruginosa. Dependence of initial pH values and range of concentrations of the dye Reactive Black B (33.2-103.1 mg l(-1)) and Cr(VI) (19.9-127.6 mg l(-1)) were examined to find the effect of pH on the dye and Cr(VI) bioaccumulation. Optimal pH for growth of the consortia in media containing 35 mg l(-1) dye and 50 mg l(-1) Cr(VI) was determined to be around 8. The Cr(VI) bioaccumulation by the consortia was rapid in media containing molasses with or without reactive dye with a maximum Cr(VI) bioaccumulation yield ranging from 90% to 99% within a 2-4d period. A slightly lower yield for the dye bioaccumulation was measured with a maximum dye bioaccumulation of 80% at 59.3 mg l(-1) dye and 69.8 mg l(-1) Cr(VI). The highest specific Cr uptake value was obtained as 76.7 mg g(-1) at 117.1 mg l(-1) Cr(VI) and 50.8 mg l(-1) dye concentration. This ability to bioaccumulate dye and Cr(VI) was more efficient than the enriched sludge from which they were isolated.  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