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   179篇
  免费   4篇
  国内免费   4篇
安全科学   5篇
废物处理   4篇
环保管理   14篇
综合类   29篇
基础理论   47篇
环境理论   1篇
污染及防治   55篇
评价与监测   20篇
社会与环境   12篇
  2023年   3篇
  2022年   6篇
  2021年   9篇
  2020年   1篇
  2019年   5篇
  2018年   13篇
  2017年   8篇
  2016年   15篇
  2015年   6篇
  2014年   10篇
  2013年   14篇
  2012年   10篇
  2011年   11篇
  2010年   4篇
  2009年   10篇
  2008年   2篇
  2007年   8篇
  2006年   9篇
  2005年   5篇
  2004年   6篇
  2003年   7篇
  2002年   5篇
  2001年   4篇
  2000年   1篇
  1999年   1篇
  1995年   1篇
  1994年   3篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1986年   1篇
  1985年   1篇
  1967年   1篇
  1966年   1篇
  1964年   1篇
排序方式: 共有187条查询结果,搜索用时 0 毫秒
131.
Real-time simultaneous studies on chemical characteristics of rainwater and PM10 aerosols were carried out to understand the scavenging of major chemical components in Indian region. The concentrations of Ca2+, NH4+, SO42− and NO3 were observed to be lower in the aerosol samples collected during rain as compared to before and after rain events. The most significant reduction was noticed for Ca2+ (74%) during rain which showed highest scavenging ratio (SR) and indicated that below-cloud scavenging is an effective removal process for Ca2+ in Indian region. Among non-sea salt components, Ca2+ had highest SR at Hyderabad indicating typical characteristics of crustal influence as abundance of calcium carbonate in soil dust has been reported in India. However, the levels of these major chemical components gradually got build-up in due course of time. After rain events, the levels of SO42− aerosols were noticed to be substantially higher (more than double) within 24 h. In general, scavenging ratios for all components (except Ca2+, NH4+ and K+) were higher over BOB as compared to Hyderabad. The maximum fall in aerosol levels (BR minus AR) was observed during continuous and low intensity rain events that did not allow building up of aerosol concentrations.  相似文献   
132.
EDTA was percolated in laboratory columns through a soil polluted by heavy metals to investigate the efficiency of and processes involved in soil decontamination by chemical extraction. At high EDTA concentration (10−2 M), elution of Pb and Cd was very efficient for one pore volume, after which it decreased to almost zero due to depletion of available Pb and Cd and to competition with Ca and Fe slowly solubilized during the passage of the EDTA front. Clogging occurred after the end of the EDTA plateau. At lower EDTA concentrations (10−3 and 10−4 M), elution was less efficient, but extraction decreased little with the volume percolated; moreover no Ca above background values was dissolved. The optimum EDTA concentration for heavy metal extraction ranges between 10−2 and 10−3 M. The higher the concentration, the greater the extraction efficiency, but as the EDTA concentration is increased there is an optimum point at which clogging takes place and permeability decreases.  相似文献   
133.
Environmental Science and Pollution Research - Modern lifestyle and alleviated anthropogenic activities have increased the pollutant load, ultimately causing stress on the environment. In...  相似文献   
134.
135.
Poland is undergoing a major systemic shift from a centrally-planned toward a market economy. All dimensions of societal life are involved in the change. The paper discusses the current role of Polish managers against the background of what it used to be like under communism from a social constructivist perspective. The role is considered from the point of view of the actors; how they construct their role.  相似文献   
136.
137.
138.
Slow growth in herbivores may lead to higher mortality, due to prolonged exposure to natural enemies. A number of studies has tested the 'slow-growth, high-mortality' hypothesis using predators or parasitoids as natural enemies of the herbivore, but the possible role of pathogens is poorly documented. We provide evidence that phytopathogenic infection of a plant enhances the susceptibility of herbivore larvae to a generalist entomopathogen. Larvae of the mustard leaf beetle Phaedon cochleariae grow more slowly when feeding on Chinese cabbage leaves infected by the phytopathogenic fungus Alternaria brassicae than larvae feeding on healthy leaves. Treatment of such larvae feeding on diseased plants with an LD50 of the entomopathogenic fungus Metarhizium anisopliae resulted in 100% mortality, compared with a mortality rate of 54% in the control larvae feeding on uninfected leaves. This is the first demonstration of an interaction between a phyto- and an entomopathogenic fungus.  相似文献   
139.
Although shell colour polymorphism of the land snail Cepaea nemoralis is a well-known phenomenon, proximate and ultimate factors driving its evolution remain uncertain. Polymorphic species show variation in behavioural responses to selective forces. Therefore, we estimated effects of various environmental factors (temperature, humidity, food availability, (micro)habitat structure and predatory pressure) on behavioural response (frequency of locomotion, climbing and hiding) of C. nemoralis morphs, in experimental and natural conditions. In the experimental part of study, the frequency of locomotion was negatively affected by temperature and the presence of food and positively influenced by the presence of light. Morphs significantly differed in behavioural responses to environmental variability. Pink mid-banded and yellow five-banded morphs climbed less often and hide in shelter more often than yellow and pink unbanded individuals when temperature was low and food was absent. Snails fed most often at moderate temperature compared to low and high temperatures. Field investigations partially confirmed differences among morphs in frequency of climbing, but not in terms of probability of hiding in sheltered sites. In natural colonies, temperature and (micro)habitat structure significantly affected frequency of climbing as well as hiding in shelter. Snails more often hid in sheltered sites where thrushes preyed on Cepaea. Tendency of unbanded morphs to climb trees may have evolved under avian predatory pressure as thrushes forage on a ground. Tendency of banded morphs to hide in sheltered sites may reflect prey preferences for cryptic background. The results implicate that differential behaviour of C. nemoralis morphs compensate for their morphological and physiological limitations of adaptation to habitat.  相似文献   
140.
Motivated by a lack of scholarly attention to the substance of interpretive messages and materials, this study examines discursive aspects of interpretative brochures available at forest recreation and tourism sites in Vermont, United States. Directive statements that instruct and guide visitor experiences—and the discourses to which they contribute—were analyzed for content, form, and meaning. Across the interpretive brochures, four broad discourses were identified: the natural forest, the recreational forest, the productive forest, and the dependent forest. Consideration of intertextuality revealed a fifth, hybrid discourse that linked forests to meanings of Vermont as a distinctive place. The convergence of these discourses across the set of brochures gives insight into the ways interpretation serves to both direct individual visitor experiences at particular sites, and to influence the development of larger-scale place meanings.  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