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   286篇
  免费   7篇
  国内免费   1篇
安全科学   11篇
废物处理   11篇
环保管理   92篇
综合类   27篇
基础理论   81篇
环境理论   1篇
污染及防治   40篇
评价与监测   14篇
社会与环境   14篇
灾害及防治   3篇
  2022年   1篇
  2021年   4篇
  2020年   4篇
  2019年   6篇
  2018年   6篇
  2017年   4篇
  2016年   6篇
  2015年   5篇
  2014年   6篇
  2013年   18篇
  2012年   21篇
  2011年   19篇
  2010年   12篇
  2009年   8篇
  2008年   11篇
  2007年   12篇
  2006年   11篇
  2005年   10篇
  2004年   11篇
  2003年   17篇
  2002年   10篇
  2001年   13篇
  2000年   3篇
  1999年   2篇
  1998年   4篇
  1997年   3篇
  1996年   3篇
  1995年   4篇
  1994年   2篇
  1993年   3篇
  1992年   4篇
  1991年   3篇
  1990年   5篇
  1989年   4篇
  1988年   4篇
  1987年   4篇
  1986年   1篇
  1985年   6篇
  1984年   6篇
  1983年   4篇
  1982年   3篇
  1980年   1篇
  1978年   3篇
  1977年   1篇
  1975年   1篇
  1974年   3篇
  1973年   1篇
  1969年   1篇
排序方式: 共有294条查询结果,搜索用时 46 毫秒
261.
Rapid environmental change in vulnerable destinations has stimulated a new form of travel termed “last chance tourism” (LCT). Studies have examined the risks of LCT, while leaving potential opportunities within this new tourism market largely underexplored. Results of survey (n?=?399) research in Jasper National Park, Canada reveal that a LCT motivation influences decisions to visit this iconic Canadian destination, and suggest that this motivation is linked to a desire to learn about the impacts of climate change on the Athabasca Glacier. Findings suggest there may be short to medium term opportunities associated with LCT, including promoting climate change ambassadorship through management interventions. This paper discusses a range of possible education, interpretive, and outreach activities that might be employed at LCT destinations. It outlines the relative merits (or what we refer to as “uneasy benefits”) of promoting the glacier and other LCT destinations within a protected areas management and climate change adaptation context.  相似文献   
262.
Changes in Arctic vegetation can have important implications for trophic interactions and ecosystem functioning leading to climate feedbacks. Plot-based vegetation surveys provide detailed insight into vegetation changes at sites around the Arctic and improve our ability to predict the impacts of environmental change on tundra ecosystems. Here, we review studies of changes in plant community composition and phenology from both long-term monitoring and warming experiments in Arctic environments. We find that Arctic plant communities and species are generally sensitive to warming, but trends over a period of time are heterogeneous and complex and do not always mirror expectations based on responses to experimental manipulations. Our findings highlight the need for more geographically widespread, integrated, and comprehensive monitoring efforts that can better resolve the interacting effects of warming and other local and regional ecological factors.  相似文献   
263.
The suitability of the enterococci surface protein (esp) marker to detect human fecal pollution was evaluated by testing 197 fecal samples from 13 host groups in Southeast Queensland, Australia. Overall, this marker was detected in 90.5% of sewage and septic system samples and could not be detected in any fecal samples from 12 animal host groups. The sensitivity of the esp primer to detect the human-specific esp marker in sewage and septic samples was 100 and 67%, respectively. The overall specificity of this marker to distinguish between human and animal fecal pollution was 100%. Its prevalence in sewage was also determined by testing samples from the raw sewage, secondary effluent, and treated effluent of a sewage treatment plant (STP) over five consecutive days. Of the 15 samples tested, 12 (80%) were found to be positive for this marker. In contrast, it was not found in three samples from the treated effluent and these samples did not contain any culturable enterococci. The PCR limit of detection of this marker in freshwater samples was up to dilution 1 x 10(-4) and the number of culturable enterococci at this dilution was 4.8 x 10(1) +/- 7.0 x 10 degrees colony forming unit (CFU). The utility of this marker was evaluated by testing water samples from three non-sewered catchments in Pine Rivers in Southeast Queensland. Of the 13 samples tested, eight were positive for this marker with the number of enterococci ranging between 1.8 x 10(3) to 8.5 x 10(3) CFU per 100 mL of water. Based on the results, it can be concluded that the esp marker appears to be sewage specific and could be used as a reliable marker to detect human fecal pollution in surface waters in Southeast Queensland, Australia.  相似文献   
264.
This study tested a relational demography model of workgroup identification. We theorized that early in workgroup formation, (a) racial identification would moderate the influence of racial dissimilarity on member communication behavior (frequency and length of verbal participation) during a group task, (b) member communication behaviors would mediate the effect of racial dissimilarity on workgroup identification, and that (c) these effects would be affected non‐symmetrically by racial group membership (White, Black). This model was tested among a sample of 211 undergraduates (113 White and 98 Black), working in 43 temporary workgroups. Whites' racial identification moderated the relationship between racial dissimilarity and member communication behaviors, which in turn partially mediated the effect of racial dissimilarity on workgroup identification, generally consistent with our model. Among Black workgroup members support for our model was limited. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
265.
This paper examines strategies for improving recycling behaviour within the Cornwall National Health Service (NHS). Using quantitative (questionnaires and waste bin analyses) and qualitative (ethnography and interviews) methodologies, the study examined the waste management practices of staff from the Cornwall NHS. It was found that employee participation in waste recycling at work was low due to a range of factors including NHS focus and policies, group norms, and individual attitudes and beliefs about sustainable waste management. Recommendations for improving the sustainability of NHS, employee waste management practices, with a specific focus on recycling are included in the paper. These recommendations include measures focused towards both the NHS organization and individual staff members.  相似文献   
266.
The option of reusing greywater is proving to be increasingly attractive to address the water shortage issue in many arid and semiarid countries. Greywater represents a constant resource, since an approximately constant amount of greywater is generated from kitchen, laundries, bathroom in every household daily, independent of the weather. However, the use of greywater for irrigation in particular for household gardening may pose major hazards that have not been studied thoroughly. In this study, a 1-year monitoring was conducted in four selected households in Perth, Western Australia. The aim of the monitoring works is to investigate the variability in the greywater flow and quality, and to understand its impact in the surrounding environments. Case studies were selected based on different family structure including number, ages of the occupants, and greywater system they used. Samples of greywater effluent (showers, laundries, bathtub, and sinks), leachate, soil, and plants at each case study were collected between October 2008 and December 2009 which covered the high (spring/summer) and low (autumn/winter) production of greywater. Physical and chemical tests were based on the literature and expected components of laundry and bathroom greywater particularly on greywater components likely to have detrimental impacts on soils, plants, and other water bodies. Monitoring results showed the greywater quality values for BOD, TSS, and pH which sometimes fell outside the range as stipulated in the guidelines. The soil analyses results showed that salinity, SAR, and the organic content of the soil increased as a function of time and affected the plant growth. Nutrient leaching or losses from soil irrigated with greywater shows the movement of nutrients and the sole impact from greywater in uncontrolled plots in case studies is difficult to predicted due to the influence of land dynamics and activities. Investigative and research monitoring was used to understand greywater irrigation in households. Greywater quality is very site specific and difficult to predetermine or control except for the use of some recommended household products when using greywater. Investigative and research monitoring was indicated that greywater quality is very site specific and difficult to predetermine or control except for the use of some recommended household products when using greywater.  相似文献   
267.
ABSTRACT: Areas of low topographic relief have low water-table gradients and make the direction of movement of contaminants from land fills in the ground water difficult to predict from regional gradients alone. The landfill, nearby free-flowing ditches or canals, variations in hydraulic conductivity, and the influence of nearby pumping wells can all affect the direction of flow. In low-gradient areas the concepts of “upgradient” and “downgradient” are less useful in planning the location of monitoring wells than in areas of higher relief. Low-relief areas also may be affected by the discharge of mineralized water from deeper aquifers, naturally or through irrigation, which can mask geochemical surveys intended to detect landfill leachate. Examples of effects of low topographic relief are noted in southeast Florida where water-table gradients are 7×10?-4 to 5×10?-4 feet per foot. Water-table mounding beneath the landfill and the drainage effects of nearby ditches and well have created multiple leachate plumes in Stuart where one plume migrated in a direction opposite to the apparent regional gradient. In Coral Springs analysis suggests a bifurcating plume migrating along two narrow zones. In Fort Pierce it was difficult to detect leachate because of mineralized irrigation water and fertilizer runoff from an adjacent citrus grove.  相似文献   
268.
Ranunculus spp. are the dominant plants of lowland chalk stream habitats in England. The spatial variability of sediment characteristics (silt–clay, organic matter, total phosphorus and total nitrogen content) within stands of Ranunculus spp. was investigated in 12 rivers in lowland England. Variability was found to be high and there were no discernible differences between samples taken from within Ranunculus and a limited number of samples from bare substrate. For two of these rivers, comparisons were also made between reaches upstream and downstream of waste water treatment works outfalls in terms of the characteristics of the sediments within Ranunculus stands. In one river a clear increase in sediment nutrient, fine and organic material content was observed downstream but in the other there was no consistent difference. Temporal variability was considered for two rivers in the Frome catchment, Dorset, by analysing the monthly variability in sediment organic matter and silt–clay content beneath Ranunculus stands over an annual cycle of growth and die-back. Whilst a clear pattern of fine and organic material retention consistent with seasonal plant growth patterns was evident at one site, the three sites displayed different temporal patterns. This inconsistency is believed to reflect differences in sediment supply at the three sites.  相似文献   
269.
An extracellular fraction from the lignin degrading white-rot fungus, Coriolus versicolor, can biosolubilize leonardite and pretreated lignites in vitro. Leonardite is often found as an overburden to lignite deposits, and is related to humic acid, and is more oxidized than lignites. Extracts from certain fungi such as C. versicolor solubilize leonardite. The biosolubilization activity is at least in part enzymatic in nature. A protein which is at least partly responsible for the solubilization effect has been substantially purified and concentrated by ultrafiltration and ion-exchange chromatography from the broth of an agitated submerged culture of C. versicolor grown in a defined medium. An in vitro coal biosolubilization assay was used to establish the effects of various physical and chemical factors affecting enzyme activity, including temperature and the salt and buffer composition of the reaction mixture. Some initial studies on the mechanism of the enzymatic leonardite biosolubilization reaction are described.  相似文献   
270.
Otolith increment age estimates for a deepwater species, Allocyttus verrucosus, were validated by comparison with the results from 210Pb:226Ra radiometric analysis. Transverse sectioning and subsequent grinding of otoliths to a thickness of 0.2 mm revealed increments which provided age estimates for a range of fish sizes. Age estimates ranged from 7 yr for an immature fish of 15.2 cm total length (TL) to 130 yr for a female fish of 36.5 cm TL. Age at maturity was estimated as 28 yr for females and 24 yr for males. In comparison, radiometric analysis of whole otoliths, using a single linear otolith-mass growth-rate model suggested maximum ages of 130 to 170 yr for fish of 34 to 35 cm TL. Radiometric ages were also recalculated using a two-phase otolith-mass growth-rate model in which the growth rate was assumed to slow after maturity to 90% of the pre-maturity rate. This reduced the maximum age to 132±15 yr for a mean fish length of 34.5 cm. Age at maturity for females was estimated at 34 yr. The similarity between age estimates from otolith-increment counts and radiometric analysis strongly supports the accuracy of results from both methods, and encourages further use of such comparisons as an alternative to traditional validation techniques.  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