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   640篇
  免费   18篇
  国内免费   9篇
安全科学   20篇
废物处理   34篇
环保管理   114篇
综合类   96篇
基础理论   143篇
环境理论   2篇
污染及防治   183篇
评价与监测   40篇
社会与环境   20篇
灾害及防治   15篇
  2023年   8篇
  2022年   13篇
  2021年   11篇
  2020年   14篇
  2019年   17篇
  2018年   22篇
  2017年   19篇
  2016年   37篇
  2015年   17篇
  2014年   22篇
  2013年   62篇
  2012年   29篇
  2011年   49篇
  2010年   30篇
  2009年   26篇
  2008年   42篇
  2007年   41篇
  2006年   29篇
  2005年   20篇
  2004年   13篇
  2003年   30篇
  2002年   21篇
  2001年   12篇
  2000年   9篇
  1999年   10篇
  1998年   3篇
  1997年   2篇
  1996年   6篇
  1995年   6篇
  1994年   2篇
  1992年   6篇
  1991年   4篇
  1990年   5篇
  1989年   2篇
  1988年   1篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1984年   3篇
  1983年   3篇
  1981年   1篇
  1979年   1篇
  1977年   1篇
  1976年   3篇
  1975年   1篇
  1974年   2篇
  1971年   1篇
  1967年   1篇
  1966年   1篇
  1964年   1篇
排序方式: 共有667条查询结果,搜索用时 234 毫秒
51.
In Hawaii, trace concentrations of pesticides used in the production of pineapple were found in the groundwater supplies of Mililani Town in the Pearl Harbor Basin on the island of Oahu. Groundwater serves as the major source of drinking water and residents pay for wellhead treatment of the contaminated water, via their monthly water bill. The agricultural chemical users within the Pearl Harbor Basin do not include these wellhead treatment costs in their production costs. The agricultural industry benefits from using pesticides but does not pay the entire societal cost of using these chemicals. In this study we evaluate the specific financial cost of wellhead treatment, and not the economic value of groundwater. While wellhead treatment costs could conceivably be shared by several parties, this study focuses on the financial impact of the pineapple industry alone. This study factors annual wellhead treatment costs into annual pineapple production costs to measure the effect on annual financial return from pineapple production. Wellhead treatment costs are calculated from the existing granulated activated carbon (GAC) water treatment facility for Millilani Wells I and II. Pineapple production costs are estimated from previous cost of production studies. The inclusion of wellhead treatment costs produces different production-cost results, depending on the scale of analysis. At the local scale, the Mililani wellhead treatment costs can be factored into the production costs of the pineapple fields, which were probably responsible for contamination of the Mililani Wells, without causing a deficit in economic return. At the larger regional scale, however, the return from all of the pineapple grown in the Pearl Harbor Basin can not sustain the cost of wellhead treatmentfor the entire water supply of the basin. Recommendations point to the prevention of groundwater contamination as more cost-effective measure than wellhead treatment.  相似文献   
52.
Abstract: Agricultural runoff, such as dissolved mineral salts and selenium, creates pronounced downstream impacts to agricultural producers and to wildlife. The ability to manage these problems efficiently depends critically on the institutional pricing structure of irrigation water delivery agencies. An important characteristic of irrigation water delivery is whether irrigators pay per unit of water received or make one payment regardless of the quantity of water received. In this study we compare the effectiveness of agricultural runoff reduction policies in two regions that employ these different water pricing structures. We find that reduction policy is more effective and can be achieved at a lower cost when water is priced on a per unit basis and that growers have greater incentive to act on their own to reduce runoff problems. Operating under a per unit pricing system encourages water conservation and runoff reduction, which creates public benefits that are not achieved under the single-payment, fixed allotment method of irrigation water delivery.  相似文献   
53.
This study develops and tests a leadership model that focuses on managers' motivation for attempting the leadership of change. The construct of leadership self‐efficacy (LSE) is defined, and a measure comprising three dimensions (direction‐setting, gaining followers' commitment, and overcoming obstacles to change) is developed. Based on Bandura's (1986) social cognitive theory, the primary hypothesis is that high LSE managers will be seen by direct reports as engaging in more leadership attempts. Relationships are also proposed between LSE and several factors that are expected to influence this confidence judgment. Managers' organizational commitment and crisis perceptions are modelled as potential moderators of the relationship between LSE and leadership attempts. The model was tested through surveys distributed to managers (n = 150) and their direct reports (n = 415) in a real estate management company and an industrial chemicals firm. Positive relationships (p < 0.05) were found between the first two dimensions of LSE and managers' leadership attempts. An interaction effect involving organizational commitment was discovered for the LSE/overcoming obstacles dimension (p < 0.05). Several positive relationships were found between LSE dimensions and proposed antecedents, including self‐esteem (p < 0.05), subordinates' performance abilities (p < 0.05), and managers' job autonomy (p < 0.05). Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
54.
Different strategies of multivariate analysis of metals concentrations (Mn, Fe, Ni, V, Co, Cu, Cd, Hg, Pb, Na, K) in mussel samples from different spanish markets are used to interpret a data base and identify differences between species and origin of the samples. Principal Component Analysis and Potential curves are applied to properly classify unknown samples from representative mussels samples (Mytilus edulis and Perna canaliculus). Also, Principal Components Analysis is used as display method to visualize the relation between the variables and objects of interest.  相似文献   
55.
Environmental changes in Sepetiba Bay,SE Brazil   总被引:2,自引:0,他引:2  
Sepetiba Bay is an example of an aquatic environment that has been severely impacted by human occupation and industrial activities in its basin. Some 400 industries including metallurgical, petrochemical and pyrometallurgical smelters, which emitted pollutants to air, soil and water, were established in Sepetiba Basin during the past 30 years. Apart from these point sources, changes in land use have also resulted in a large remobilization of pollutant deposition on Sepetiba Bay Basin. Studies have pointed out significant changes in sedimentation rates, concentrations of inorganic pollutants (Zn, Cd, Pb and Hg) and more recently, eutrophication, pointing to this area as an example of an impacted coastal zone. Notwithstanding local sources, Sepetiba Bay also suffers environmental impacts caused by diversion of river waters from adjacent basins, with some 30% of the total Hg flux to Sepetiba Bay and a 10-fold increase in water and sediment fluxes resulting from this. Decreasing environmental quality compromises both the large biodiversity and the potential economic uses of Sepetiba Bay, including fisheries and tourism. Monitoring of heavy metal levels in organisms (algae, mollusks, crustaceans and oysters) often shows concentrations well above the limits allowed following Brazilian legislation for food quality. Historical evolution of these concentrations suggests a worsening of the situation. Failure to monitor the effect of land-based activities, including those from other basins artificially associated with Sepetiba Bay has resulted in poor scenario construction and proper management planning.  相似文献   
56.
Most harvestmen are nocturnal, nonacoustical, and nonvisual arthropods. They have a pair of exocrine glands on the cephalothorax that produce defensive volatile secretions. We investigated in the field the possible alarm effect of these secretions in the gregarious harvestman Goniosoma aff. proximum. A cotton swab soaked with the species' own exudate (treatment), or with water (control), was held 1-2 cm from the center of harvestmen aggregations. The results showed that the gland secretion elicits an alarm response in Goniosoma: whereas 73.3% of the aggregations dispersed after being stimulated with the gland exudate, only 3.3% responded to the water control. Respondent groups are larger than nonrespondent groups, and the time of reaction to the secretion was inversely related to group size. This is the first demonstration of a chemically-mediated alarm effect in harvestmen. The alarm response in gregarious harvestmen has possibly evolved as a by-product of a primarily defensive reaction in the context of predator avoidance. The discovery of this novel function of scent-gland secretion is meaningful in view of the widespread occurrence of gregarious habit among species of the order Opiliones.  相似文献   
57.
Residents' perceptions of water quality change following remediation work in the upper Pymme's Brook catchment (north London) were elicited by questionnaire and compared with monitored changes in Escherichia coli count and BMWP (The Biological Monitoring Working Party (BMWP)) score. The wider usefulness of consumer perception surveys was then discussed. Monthly data collected between 1990 and 1996 shows that both E. coli count and BMWP score improved following flushing of the foul sewerage system in 1992, but that only E. coli count improved following the subsequent completion of large-scale remedial engineering works. Local residents were surveyed regarding their awareness of the scheme, and the causes of pollution, together with their perceptions as to the effects of the engineering works and of the resulting water quality improvements. Most respondents selected and ranked indicators in a way that suggested they had an awareness of the significance of various indicators of pollution severity. Following completion of the remediation scheme, residents perceived the watercourse to contain less rubbish and sewage fungus, and to have an improved colour and smell, which corresponds favourably to the monitored improvements. However, respondents' perceptions were found to vary when the study population was sub-divided using a range of parameters. For instance, frequent observers of the brook were most likely to correctly identify sewage as the main form of pollution. These divergent perceptions suggest that there may be considerable difficulties when perception surveys are used to quantify 'benefits' following environmental improvement programmes. Nevertheless, the survey was clearly beneficial in enhancing residents' awareness of their environment and the role of their voice in its management.  相似文献   
58.
UVONNE FU 《绿叶》2007,(11):60-61
葛玉修,山东人,现任青海银监局纪委书记,中国摄影家协会会员、中国金融摄影家协会副主席、中国艺术摄影学会会员、青海省摄影家协会理事,"青海青"网站站长,被誉为青海湖"鸟王"和"中华对角羚之父"。十年来他利用自己的节假日拍摄野生动物,捕捉了三万多个震撼人心的瞬间。  相似文献   
59.
ABSTRACT

It is the promise of smart grids – their anticipated role in meeting economic, social, environmental policy objectives – that is driving action on smart grids worldwide, while the reality is rather more messy. This paper is about the implementation of smart grids in Australia, and examines the degree to which environmental and social promises have materialised (or not) within two large energy smart grid initiatives undertaken in the period 2009–2014: the federal government-sponsored Smart Grid Smart City Program and the State of Victoria’s Advanced Metering Infrastructure Program. The analysis draws on a governmentality approach to examine how the promise of smart grids has not for the most part been delivered, concentrating in particular on how new digital technologies have not “behaved” in the way originally planned. Within a governmentality framework, it is generally assumed that technologies work to support government programmes, to accomplish governance. But growing evidence points to smart grid technologies undermining the promise of smart grids. Such a finding stands at odds with the assumption in governmentality about technologies doing work in consort with rationalities of government.  相似文献   
60.
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