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   112篇
  免费   1篇
安全科学   4篇
废物处理   2篇
环保管理   24篇
综合类   22篇
基础理论   23篇
污染及防治   22篇
评价与监测   5篇
社会与环境   8篇
灾害及防治   3篇
  2022年   2篇
  2020年   3篇
  2019年   3篇
  2018年   8篇
  2017年   3篇
  2016年   8篇
  2015年   4篇
  2014年   3篇
  2013年   8篇
  2012年   2篇
  2011年   7篇
  2010年   1篇
  2009年   10篇
  2008年   3篇
  2007年   11篇
  2006年   6篇
  2005年   2篇
  2004年   2篇
  2003年   7篇
  2002年   2篇
  2001年   5篇
  2000年   1篇
  1998年   1篇
  1997年   3篇
  1995年   1篇
  1993年   2篇
  1992年   1篇
  1970年   1篇
  1962年   3篇
排序方式: 共有113条查询结果,搜索用时 14 毫秒
101.
Employment after retirement, known as bridge employment, is expected to occur more frequently because the baby boom generation will increase the number of retirees. Little is known about which employees will obtain which type of bridge employment when they retire, even though it has important implications. The present study examined work‐related attitudes, job characteristics, and work‐related accomplishments of 171 retirees in order to predict whether they would fully retire or take one of two types of bridge jobs after retirement: Career‐consistent bridge jobs or bridge jobs in fields different from their original career. Continuity theory of retirement helped predict post‐retirement employment type. Retirees who had skills specifically related to their career job were more likely to work in a career‐related bridge job than either to fully retire or to take a bridge job that was not related to their careers; retirees who formerly held career jobs with intrinsically motivating job characteristics were more likely to take a career‐related bridge job than to retire fully, and retirees who had experienced work strain in their career job were more likely to take a bridge job not related to their former career than to take a career bridge job. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
102.
The forest–grassland mosaics of southern Brazil have been subject to many land use and policy changes over the decades. Like many grasslands around the world, the Campos grasslands are declining with few conservation efforts underway. In contrast, forests receive much attention and many incentives. It is hypothesized that perception of land cover has the potential to shape ecosystems. Here we conduct a questionnaire to further our understanding of decision-making practices that alter landscapes (Campos grassland, Araucaria forest, agriculture and plantation) and direct land policies in the region. Our analysis reveals that plantations are significantly less desirable than the other landscape types. However, plantation land use has increased by 87 % over the past few decades, as a result of industry and government incentives. The proportions of other landscape types have remained consistent over the past two decades. Restoration of native vegetation is not a priority of landowners and restoration would require a financial incentive.  相似文献   
103.
The North Water is a recurrent polynya in the High Arctic situated between Northwest Greenland and Ellesmere Island of Canada. The North Water makes a dynamic space, where various processes may enhance or obstruct each other, accelerating or halting particular modes of human–animal relations in the region, where life itself depends on the North Water. This will be discussed in four steps. The first step posits the North Water as a perceived oasis for explorers and whalers hailing from Europe or America in the nineteenth century. The second step concentrates on the diverse rhythms inherent in the ice conditions, as affected by trends that are set in motion elsewhere. The third step highlights the implications of the dynamics of the ice and sea currents for animal life in the region. The fourth step gives an overview of human settlement patterns around the North Water across the ages. The article shows how natural and social features are deeply implicated in each other, even if they are not directly co-variant.  相似文献   
104.
Stable carbon and hydrogen isotopes can be an efficient means to validate biodegradation of organic contaminants in groundwater since it results in an isotopic fractionation. A prerequisite in applying this method in the field is the proof that other processes decreasing the contaminant concentration are conservative with respect to isotope effects. In this paper we show for carbon isotopes of halogenated hydrocarbon compounds [trichloroethene (TCE), cis-dichloroethene (c-DCE), vinylchloride (VC)] and carbon and hydrogen isotopes of BTEX compounds (benzene, toluene, p-xylene) that no significant fractionation occurs during equilibrium sorption onto activated carbon, lignite coke and lignite. In general, effects were in the range of the reproducibility limit of the analytical instrument (0.5 per thousand for delta13C, and 8 per thousand for delta2H). This observation was made for fractions sorbed of less than 5% to more than 95%. Also for rate-limited sorption of TCE onto activated carbon, no significant fractionation in carbon isotopes could be observed. These findings support the assumption that for these classes of compounds, sorption processes in aquifer systems are conservative with respect to isotope effects.  相似文献   
105.
106.
107.
Pyrocystis lunula is a unicellular, marine, photoautotrophic, bioluminescent dinoflagellate. This organism is used in the Lumitox bioassay with inhibition of bioluminescence re-establishment as the endpoint. Experiments determined if acute changes in pH, salinity, or temperature had an effect on the organisms' ability to re-establish bioluminescence, or on the bioassay's potential to detect sodium dodecyl sulfate (SDS) and copper toxicity. The re-establishment of bioluminescence itself was not very sensitive to changes in pH within the pH 6-10 range, though reducing pH from 8 to levels below 6 decreased this capacity. Increasing the pH had little effect on Cu or SDS toxicity, but decreasing the pH below 7 virtually eliminated the toxicity of either compound in the bioassay. Lowering the salinity from 33 to 27 per thousandth or less resulted in a substantial decrease in re-establishment of bioluminescence, while increasing the salinity to 43 or 48 per thousandth resulted in a small decline. Salinity had little influence on the bioassay's quantification of Cu toxicity, while the data showed a weak negative relationship between SDS toxicity and salinity. Re-establishment of bioluminescence showed a direct dependence on temperature, but only at 10 degrees C did temperature have an obvious effect on the toxicity of Cu in this bioassay.  相似文献   
108.
Does Autonomy Count in Favor of Labeling Genetically Modified Food?   总被引:1,自引:1,他引:1  
In this paper I argue that consumerautonomy does not count in favor of thelabeling of genetically modified foods (GMfoods) more than for the labeling of non-GMfoods. Further, reasonable considerationssupport the view that it is non-GM foods ratherthan GM foods that should be labeled.  相似文献   
109.
110.
Alloparental care poses an evolutionary dilemma because effort is expended on non-filial offspring. Thus, instances of alloparental care have been attributed to either mistaken identity, (i.e., recognition errors) or active cooperation. In greater spear-nosed bats (Phyllostomus hastatus), reproductive females roost together in stable long-term social groups in cave ceilings. Non-volant pups frequently fall from roost sites to the cave floor where they can die unless retrieved by an adult. In this study, we examined the function of adult female visits to non-filial young and tested whether visits were attributable to recognition errors or to cooperation. We found that females visited non-filial pups from their own social group more than expected. Females from different social groups attacked and sometimes killed pups, and male pups were attacked more frequently than female pups. Visits by group mates benefited fallen pups by reducing the likelihood of attack by females from other groups. In contrast to the mistaken identity hypothesis, we found that some females leave their own pups to approach and remain with group mates’ pups. We used microsatellite markers to estimate relatedness and test whether kinship could explain this alloparental care and found that females were unrelated to the pups they guard. We conclude that females who reside in highly stable social groups exhibit cooperative behavior that cannot be explained by kinship and is unlikely to be due to direct or generalized reciprocity. Instead, our data suggest that alloparental care likely involves a complex interplay between group membership and cooperative foraging.  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