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   73篇
  免费   2篇
安全科学   6篇
环保管理   4篇
综合类   16篇
基础理论   27篇
污染及防治   13篇
评价与监测   6篇
社会与环境   2篇
灾害及防治   1篇
  2023年   3篇
  2022年   4篇
  2021年   1篇
  2020年   1篇
  2019年   2篇
  2017年   4篇
  2016年   1篇
  2015年   3篇
  2014年   3篇
  2013年   6篇
  2012年   4篇
  2011年   5篇
  2010年   3篇
  2009年   3篇
  2008年   1篇
  2007年   5篇
  2006年   7篇
  2005年   3篇
  2003年   2篇
  2002年   3篇
  2001年   2篇
  2000年   2篇
  1999年   1篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1990年   1篇
  1983年   2篇
排序方式: 共有75条查询结果,搜索用时 265 毫秒
41.
42.
This paper assesses the cost-effectiveness of, and the return on the investment in, the 2002 catch-up and the 2003 follow-up measles campaigns in Afghanistan from the perspective of the donor. The catch-up campaign targeted nearly 12 million children aged between six months and 12 years, while the follow-up campaign targeted over five million children aged between 9 and 59 months. Both campaigns successfully vaccinated approximately 96 per cent of the respective target populations, and are expected to avert an estimated 301,000 measles deaths over the next 10 years. The average cost per dose of measles vaccine delivered was USD 0.40. The cost per death prevented is USD 23.6, assuming a case fatality rate of 10 per cent and a discount rate of three per cent. With more than 42,000 measles deaths avoided for every one million US dollars spent, the campaigns are an excellent public health investment for precluding childhood mortality in a country affected by a complex emergency.  相似文献   
43.
A new index named Air Quality Balance Index (AQBI), which is able to characterise the amount of pollution level in a selected area, is proposed. This index is a function of the ratios between pollutant concentration values and their standards; it aims at identifying all situations in which there is a possible environmental risk even when several pollutants are below their limit values but air quality is reduced. AQBI is evaluated by using a high-resolution three-dimensional dispersion model: the air concentration for each substance is computed starting from detailed emissions sources: point, line and area emissions hourly modulated. This model is driven with accurate meteorological data from ground stations and remote sensing systems providing vertical profiles of temperature and wind; these data are integrated with wind and temperature profiles at higher altitudes obtained by a Local Area Model. The outputs of the dispersion model are compared with pollutant concentrations provided by measuring stations, in order to recalibrate emission data. A three-dimensional high resolution grid of AQBI data is evaluated for an industrial area close to Alessandria (Northern Italy), assessing air quality and environmental conditions. Performance of AQBI is compared with the Air Quality Index (AQI) developed by the U.S. Environmental Protection Agency. AQBI, computed taking into account all pollutants, is able to point out situations not evidenced by AQI, based on a preset limited number of substances; therefore, AQBI is a good tool for evaluating the air quality either in urban and in industrial areas. The AQBI values at ground level, in selected points, are in agreement with in situ observations.  相似文献   
44.
ABSTRACT

This study reports on the occupational inhalation exposure to VOCs of workers in the Kuwaiti printing industry. Using the evacuated canister methodology, we targeted 72 VOCs in three printeries and compared the concentrations to previous reports and relevant occupational exposure levels (OELs). We found that recent efforts in the printing industry to reduce VOC usage had been successful, as concentrations of key hazardous VOCs were substantially lower than anticipated. On the other hand, nearly all target VOCs were found. Non-production areas were sampled along with the offset printing areas, another strength of this study, and revealed exposures to hazardous VOCs among administers and digital printer and CTP operators. Exposure to ototoxic VOCs amounted to 1–3% of the OEL, consisting mostly of ethylbenzene, which was likely in use in two of the study printeries. Exposure to carcinogenic or probably carcinogenic VOCs was 15–20% of the OEL at four locations across the three printeries, consisting mostly of vinyl chloride and benzyl chloride. Vinyl chloride VOC was partially sourced from outdoors, but was also likely used inside the study printeries. Interestingly, concentrations of vinyl chloride were similar in most sampling locations to that of CFC-114, a CFC banned by the Montreal Protocol and not commonly used as a refrigerant. This unexpected finding suggests further study is warranted to identify the use of these VOCs in printeries. Exposure to hazardous VOCs up to nearly 50% of the OEL, consisting largely of bromoform and vinyl chloride. Bromoform was found in all the study printeries, sourced partially from outdoor air. The higher concentrations found inside the study printeries likely resulted from the use of the desalinated water for washing. This finding raises of emissions from sources other than blanket washes, and inks, etc. adding to the total VOC load in printery indoor air.

Implications: Results from this study indicate that efforts to reduce worker exposure to VOCs particularly dangerous to human health in recent years have been successful, but there is still much to be done to protect workers. Exposures to ototoxic and carcinogenic VOCs were identified, among both production and non-production workers. Unexpected findings included the apparent use in printing activities of the carcinogen vinyl chloride and CFC-114, banned under the Montreal Protocol. Observed lapses in safety procedures included failure to utilize ventilation systems and closing doors between work areas, indicating management and worker education should remain a priority.  相似文献   
45.
The performance of a new anion exchanger (AE) prepared from coconut coir pith (CP), for the removal of arsenic(V) [As(V)] from aqueous solutions was evaluated in this study. The adsorbent (CP-AE) carrying dimethylaminohydroxypropyl weak base functional group was synthesized by the reaction of CP with epichlorohydrin and dimethylamine followed by treatment of hydrochloric acid. IR spectroscopy results confirm the presence of -NH(+)(CH(3))(2)Cl(-) group in the adsorbent. XRD studies confirm the decrease of crystallinity in CP-AE compared to CP, and it favours the protrusion of the functional group into the aqueous medium. Batch experiments were conducted to examine the efficiency of the adsorbent on As(V) removal. Maximum removal of 99.2% was obtained for an initial concentration of 1 mgl(-1) As(V) at pH 7.0 and an adsorbent dose of 2 gl(-1). The kinetics of sorption of As(V) onto CP-AE was described using the pseudo-second-order model. The equilibrium isotherms were determined for different temperatures and the results were analysed using the Langmuir equation. The temperature dependence indicates an exothermic process. Utility of the adsorbent was tested by removing As(V) from simulated groundwater. Regeneration studies were performed using 0.1N HCl. Batch adsorption-desorption studies illustrate that CP-AE could be used to remove As(V) from ground water and other industrial effluents.  相似文献   
46.
The present work considers the section of the Mesta River on Bulgarian territory using the integral method for evaluation of climate and anthropogenic impact on the river flow. The level of this impact is determined by the index K i (flow module), the coefficient C i for the deviation of the average annual water volume Q i from the flow norm Q o and the index h i for the deviation of the average annual rainfall volume H i from the average multi-annual rainfall volume H o . The dynamics of the average annual flow Q i at two typical hydrometric stations – Yakoruda and Khadzhidimovo, as well as the dynamics of the average annual rainfall for the Yakoruda station was examined for the period 1955–2003. The data for the considered period 1955–2003 exhibit a decreasing trend of the average annual water volumes dynamics for both stations due to the impact of climate changes in the Mesta River catchment.  相似文献   
47.
48.
Proactive approaches that anticipate the long-term effects of current and future conservation threats could increase the effectiveness and efficiency of biodiversity conservation. However, such approaches can be obstructed by a lack of knowledge of habitat requirements for wildlife. To aggregate and assess the suitability of current information available on habitat requirements needed for proactive conservation, we conducted a systematic review of the literature on elephant and rhinoceros habitat requirements and synthesized data by combining a vote counting assessment with bibliometric and term maps. We contextualized these numeric and terminological results with a narrative review. We mapped current methods, results, terminology, and collaborations of 693 studies. Quantitative evidence for factors that influence the suitability of an area for elephants and rhinoceros was biased toward African savanna elephants and ecological variables. Less than one third of holistic approaches considered equal amounts of ecological and anthropogenic variables in their assessments. There was a general lack of quantitative evidence for direct proxies of anthropogenic variables that were expected to play an important role based on qualitative evidence and policy documents. However, there was evidence for a segregation in conceptual frameworks among countries and species and between science versus policy literature. There was also evidence of unused potential for collaborations among southern hemisphere researchers. Our results indicated that the success of proactive conservation interventions can be increased if ecological and anthropogenic dimensions are integrated into holistic habitat assessments and holistic carrying capacities and quantitative evidence for anthropogenic variables is improved. To avoid wasting limited resources, it is necessary to form inclusive collaborations within and across networks of researchers studying different species across regional and continental borders and in the science–policy realm.  相似文献   
49.
• Cellulose-based membrane separates oily wastewater mimicking the living things. • The three central surface mechanisms were reviewed. • Preparation, performance, and mechanism are critically evaluated. • First review of wettability based cellulose membrane as major material. • The current and future importance of the research are discussed. It is challenging to purify oily wastewater, which affects water-energy-food production. One promising method is membrane-based separation. This paper reviews the current research trend of applying cellulose as a membrane material that mimics one of three typical biostructures: superhydrophobic, underwater superoleophobic, and Janus surfaces. Nature has provided efficient and effective structures through the evolutionary process. This has inspired many researchers to create technologies that mimic nature’s structures or the fabrication process. Lotus leaves, fish scales, and Namib beetles are three representative structures with distinct functional and surface properties: superhydrophobic, underwater superoleophobic, and Janus surfaces. The characteristics of these structures have been widely studied and applied to membrane materials to improve their performance. One attractive membrane material is cellulose, which has been studied from the perspective of its biodegradability and sustainability. In this review, the principles, mechanisms, fabrication processes, and membrane performances are summarized and compared. The theory of wettability is also described to build a comprehensive understanding of the concept. Finally, future outlook is discussed to challenge the gap between laboratory and industrial applications.  相似文献   
50.
To determine the distribution and causes of extinction threat across functional groups of terrestrial vertebrates, we assembled an ecological trait data set for 18,016 species of terrestrial vertebrates and utilized phylogenetic comparative methods to test which categories of habitat association, mode of locomotion, and feeding mode best predicted extinction risk. We also examined the individual categories of the International Union for Conservation of Nature Red List extinction drivers (e.g., agriculture and logging) threatening each species and determined the greatest threats for each of the four terrestrial vertebrate groups. We then quantified the sum of extinction drivers threatening each species to provide a multistressor perspective on threat. Cave dwelling amphibians (p < 0.01), arboreal quadrupedal mammals (all of which are primates) (p < 0.01), aerial and scavenging birds (p < 0.01), and pedal (i.e., walking) squamates (p < 0.01) were all disproportionately threatened with extinction in comparison with the other assessed ecological traits. Across all threatened vertebrate species in the study, the most common risk factors were agriculture, threatening 4491 species, followed by logging, threatening 3187 species, and then invasive species and disease, threatening 2053 species. Species at higher risk of extinction were simultaneously at risk from a greater number of threat types. If left unabated, the disproportionate loss of species with certain functional traits and increasing anthropogenic pressures are likely to disrupt ecosystem functions globally. A shift in focus from species- to trait-centric conservation practices will allow for protection of at-risk functional diversity from regional to global scales.  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