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   241篇
  免费   2篇
安全科学   1篇
废物处理   11篇
环保管理   19篇
综合类   30篇
基础理论   38篇
污染及防治   88篇
评价与监测   29篇
社会与环境   22篇
灾害及防治   5篇
  2023年   2篇
  2022年   3篇
  2021年   5篇
  2020年   8篇
  2019年   2篇
  2018年   10篇
  2017年   6篇
  2016年   5篇
  2015年   7篇
  2014年   13篇
  2013年   19篇
  2012年   20篇
  2011年   18篇
  2010年   10篇
  2009年   18篇
  2008年   14篇
  2007年   18篇
  2006年   19篇
  2005年   6篇
  2004年   11篇
  2003年   9篇
  2002年   5篇
  2001年   2篇
  2000年   1篇
  1999年   2篇
  1998年   2篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1991年   1篇
  1990年   1篇
  1987年   1篇
  1985年   2篇
排序方式: 共有243条查询结果,搜索用时 15 毫秒
61.
Tire debris (TD) and its organic components were identified as a main source of PM10 atmospheric and water pollution. Because few data are available on the embryotoxic effects of TD organic components, the lethal and teratogenic potential of tire debris organic extract (TDOE) was evaluated using the frog embryo teratogenesis assay-Xenopus (FETAX), coupled with a histopathological screening of the survived larvae. From stage 8 to stage 47, Xenopus laevis embryos were exposed to TDOE at concentrations of 50, 80, 100, 120 and 140 mg/L. The results showed 50 mg/L TDOE to be the non-observable effect concentration (NOEC). TDOE mortality at 80 mg/L was significantly higher than the control, but did not increase further with higher concentrations. A good concentration-response was observed for percentages of malformed larva and from 80 mg/L on these percentages were significantly higher than the control. Therefore, probit analysis gave a 144.6 mg/L TC50. At 120 and 140 mg/L, many larvae were plurimalformed. The most frequent alterations observed were abnormal gut coiling, microphthalmia, monolateral anophthalmia, and narrowing eyes. The histological screening mainly revealed ocular malformations such as double retina, retina nervous cell layer coiling, and altered lens. Moreover severe vacuolisation and necrosis were scored in liver and axial musculature. These results strongly support the assumption that TDOE is a powerful teratogen for X. laevis.  相似文献   
62.
In recent years, Amazonian deforestation has become a question of global concern. Deforestation in Amazon is a complex phenomenon in nature and has been related to traditional agriculture expansion. In this work, land use, socioeconomic and conservation indicators, combined with statistical analysis, were used to understand forces associated with patterns of deforestation. This approach was applied in Southern Brazilian Pre-Amazon in Mato Grosso State, which represents an extensive rain forest-savanna ecotone, located in the south border of Amazon biome. Based on data from the last two agricultural censuses (1995/1996–2006), we compared agricultural expansion in this area and Mato Grosso state. Results have shown that 85 % of state deforestation was concentrated in Southern Pre-Amazon and was closely related to increase in number of cattle and pasture area. PCA results pointed that population (92 %), number of cattle (86.5 %), pastures (84.2 %) and tractors (78.4 %) were variables with highest positive correlation to deforestation. It showed that GDP contributes to an individual axis and has a low correlation to deforestation (37.8 %). Conservation units and indigenous reserves also contribute to a single axis and were negatively correlated to temporary crops area. Results revealed a significant reduction in production and commercialization of extractive products in the region, revealing that the main, almost only conservation policy in Mato Grosso remains the creation of Special Areas. We suggest that further studies are necessary to screen development alternatives to simple cutting trees down. It is important to diversify strategies for deforestation control, and development aspects must be more seriously considered to reach a sustainable deforestation control policy.  相似文献   
63.
This study examines stress and mood outcomes in community volunteers who undertook one week's worth of post‐disaster relief work in L'Aquila, Italy, which had been hit by an earthquake four months earlier. The study team obtained pre‐ and post‐relief work data from 130 volunteers involved in activities such as preparing food for the displaced, cleaning the camps and distributing clean linen. The Perceived Stress Scale, the State‐Trait Anxiety Inventory and the Profile of Mood States were administered at the start and at the end of the aid activities. Psychopathological symptoms and empathy were assessed in the beginning, using the Symptom Checklist 90 Revised and the Interpersonal Reactivity Index, respectively. The results show that, following the assistance work, volunteers displayed decreases in perceived stress, general distress, anxiety and anger, as well as increases in positive emotions. The empathy facets empathic concern and personal distress showed different patterns in modulating the post‐disaster relief work adaptation for some of the mood outcomes.  相似文献   
64.
The Amazon region represents approximately 35% of the Brazilian coastline and includes the states of Amapá, Pará, and Maranh?o. After several years, the Amazon coastal zone has not made clear progress and has failed to show important results in terms of management plans based on the weak societal and local community support, the absence of a strong institutional coordination, and the scarcity of resources. This study aims to present and discuss the existence of others important factors that have obstructed the development of these plans, specifically, describing and analyzing the uncertainties regarding the redefinition of coastal zone boundaries, integrated management concepts, stake-holders responsibility, and governmental disinterest associated with the area by the government and society. Finally, it is considered the possibility of the emergence of new driving forces for the implementation and development of the State Coastal Zone Management Plan in the Amazon region among which the following stand out: the territorial fragmentation of the states in the Amazon coastal zone, the increased exploitation pressure for coastal zone resources, and the role of global climatic change on coastal areas.  相似文献   
65.
Feeding ecology of juvenile green turtles (Chelonia mydas) was studied from 2008 to 2011 at Samborombón Bay (35°30′–36°30′S, Argentina), combining data on digestive tract examination and stable isotope analysis through a Bayesian mixing model. We found that animal matter, in particular gelatinous plankton, was consumed in large proportions compared to herbivorous food items such as terrestrial plants and macroalgae. This diet is facilitated by the high abundance of gelatinous plankton in the region, thus confirming the adaptive foraging behaviour of the juveniles according to prey abundance in the SW Atlantic. To our knowledge, this is the first study to employ this combination of techniques and to conclusively demonstrate that animal matter, in particular gelatinous plankton, is important in the diet of the neritic green sea turtles.  相似文献   
66.
Knowing the trophic ecology of marine predators is essential to develop an understanding of their ecological role in ecosystems. Research conducted on deep-sea and threatened shark species is limited. Here, by combining analyses of individual stomach contents and stable isotope values, we examined the trophic ecology (dietary composition and trophic position) of the kitefin shark Dalatias licha, a deep-sea shark considered as near threatened globally and as data deficient in the Mediterranean Sea. Results revealed the importance of small sharks in the diet of the kitefin shark at short- and long-term scales, although fin-fish, crustaceans and cephalopods were also found. Predation on sharks reveals the high trophic position of the kitefin shark within the food web of the western Mediterranean Sea. Stable isotope values from liver and muscle tissues confirmed our results from stomach content analysis and the high trophic position.  相似文献   
67.

The aim of this study was to obtain information on the presence and levels of hazardous organic pollutants in groundwater located close to solid waste landfills. Eighty-two environmental contaminants, including 16 polycyclic aromatic hydrocarbons (PAHs), 20 volatile organic compounds (VOCs), 29 polychlorinated biphenyls (PCBs), 7 dioxins (polychlorinated dibenzo-p-dioxins, PCDDs) and 10 furans (polychlorinated dibenzofurans, PCDFs) were monitored in areas characterised by different geological environments surrounding three municipal solid waste landfills (Palermo, Siculiana and Ragusa) in Sicily (Italy) in three sampling campaigns. The total concentrations of the 16 PAHs were always below the legal threshold. Overall, the Fl/Fl + Py diagnostic ratio revealed that PAHs had a petrogenic origin. VOC levels, except for two notable exceptions near Palermo landfill, were always below the legal limit. As concerns PCB levels, several samples were found positive with levels exceeding the legal limits. It is worth noting that the % PCB distribution differs from that of commercial compositions. In parallel, some samples of groundwater containing PCDDs and PCDFs exceeding the legal threshold were also found. Among the 17 congeners monitored, the most abundant were the highest molecular weight ones.

  相似文献   
68.
Nitrogen removal in wetlands is achieved through two pathways: (a) N cycling and (b) storage. N cycling is a permanent removal pathway. There has been an increasing interest in the development of technologies to alleviate permanent nitrogen removal limitation in constructed wetlands by ensuring prevalence of conditions enhancing N cycling. The purpose of this study is to review an emerging technology of vegetated submerged bed constructed wetland system aimed at improving nitrogen removal in wetlands through rational system design. The design and performance of this system type is evaluated. The oxygen transfer capacity and nitrogen removal mechanisms on system performance are evaluated. Constructed wetland combinations most commonly consist of vertical flow (VF) and horizontal flow (HF) beds where VF and HF are aimed at nitrification and denitrification, respectively. Nitrate nitrogen accumulation is the most limiting factor in typical VF based systems.  相似文献   
69.
Chemical, electrochemical and flow variables were optimized to examine the effectiveness of the electrocoagulation process for the removal of copper, lead and cadmium. The electrochemical process, which uses electrodes of commercial laminate steel, was applied to simulated wastewater containing 12 mg dm(-3) of copper, 4 mg dm(-3) of lead and 4 mg dm(-3) of cadmium. The optimum conditions for the process were identified as pH=7, flow rate=6.3 cm(3) min(-1) and a current density between 31 and 54 A m(-2). When the electrode geometric area and time of electrolysis reached critical values, the copper removal reached a maximum value of 80%. A linear relationship was identified between the current density and the mass of generated sludge. In addition, a linear relationship was found between specific energy consumption and current density. The results of this investigation provide important data for the development of an industrial-scale electrolytic reactor.  相似文献   
70.
Environmental and Ecological Statistics - Estimating bird and bat mortality at wind facilities typically involves searching for carcasses on the ground near turbines. Some fraction of carcasses...  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