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   215篇
  免费   6篇
  国内免费   11篇
安全科学   1篇
废物处理   3篇
环保管理   57篇
综合类   36篇
基础理论   48篇
污染及防治   39篇
评价与监测   33篇
社会与环境   5篇
灾害及防治   10篇
  2024年   1篇
  2022年   1篇
  2021年   5篇
  2020年   4篇
  2019年   7篇
  2018年   3篇
  2017年   2篇
  2016年   8篇
  2015年   6篇
  2014年   7篇
  2013年   27篇
  2012年   7篇
  2011年   12篇
  2010年   7篇
  2009年   18篇
  2008年   17篇
  2007年   19篇
  2006年   15篇
  2005年   10篇
  2004年   11篇
  2003年   10篇
  2001年   5篇
  2000年   6篇
  1999年   7篇
  1998年   1篇
  1996年   1篇
  1995年   3篇
  1993年   4篇
  1992年   1篇
  1991年   1篇
  1988年   1篇
  1987年   3篇
  1986年   1篇
  1981年   1篇
排序方式: 共有232条查询结果,搜索用时 46 毫秒
201.
Using the approach established by EPA's Environmental Monitoring and Assessment Program (EMAP), a shoreline monitoring survey was conducted in August and September 1999, encompassing the Florida Panhandle from Perdido Key, Florida to Port St. Joe, Florida. The objective of this survey was to demonstrate the use of a probabilistic survey for monitoring and estimating the condition of swimmable beach areas. Thirty stations were sampled using a probabilistic sampling design. Hydrographic data were collected in addition to samples for water chemistry. Bacterial indicators, enterococci and fecal coliforms, were enumerated from the water according to the EPA Beaches Environmental Assessment Closure and Health (BEACH) Program and Florida state guidelines. Additional criteria for site condition included the presence or absence of primary and secondary dunes, anthropogenic debris and vegetation. Based on EMAP evaluation guidelines and Florida state criteria, a baseline assessment of the condition of the Gulf of Mexico beach resources surveyed is presented.  相似文献   
202.
Understanding nature as an outcome of organising discourses generated through relative experiences of our surroundings has been the groundwork of a political ecology that deals with the distribution of environmental justice among people with different degrees of power. In this paper, we examine how the environmental legislation and the tourism industry have constructed the term Caiçara as a way to categorise the inhabitants of the Atlantic Forest Coast of Brazil, in ways that meet their goals, but in turn occludes the discourse of the Caiçara themselves. Ethnographic research conducted in Ponta Negra, a small coastal community located at the heart of the Juatinga Ecological Reserve (Paraty, Rio de Janeiro State), as well as a review of key legislation, management plans and tourism materials form the empirical basis of this research. First, we offer a critical examination of the historical origin of the term Caiçara. We then compare contradictory ideas of Caiçara produced by Brazilian environmental legislation and the tourism industry. While the environmental legislation has characterised the Caiçara as fallen angels who are no longer conservation allies, the tourism industry has profited by selling them as ecologically noble savages who still live in harmony with the environment. Our analysis shows how Ponta Negra people have become objects of powerful discourses of nature that hinder the recognition of their collective rights and weaken their position to negotiate for their own desires and aspirations related to their identity and livelihoods.  相似文献   
203.
Humpback whales (Megaptera novaeangliae) are managed by the International Whaling Commission as 7 primary populations that breed in the tropics and migrate to 6 feeding areas around the Antarctic. There is little information on individual movements within breeding areas or migratory connections to feeding grounds. We sought to better understand humpback whale habitat use and movements at breeding areas off West Africa, and during the annual migration to Antarctic feeding areas. We also assessed potential overlap between whale habitat and anthropogenic activities. We used Argos satellite‐monitored radio tags to collect data on 13 animals off Gabon, a primary humpback whale breeding area. We quantified habitat use for 3 cohorts of whales and used a state‐space model to determine transitions in the movement behavior of individuals. We developed a spatial metric of overlap between whale habitat and models of cumulative human activities, including oil platforms, toxicants, and shipping. We detected strong heterogeneity in movement behavior over time that is consistent with previous genetic evidence of multiple populations in the region. Breeding areas for humpback whales in the eastern Atlantic were extensive and extended north of Gabon late in the breeding season. We also observed, for the first time, direct migration between West Africa and sub‐Antarctic feeding areas. Potential overlap of whale habitat with human activities was the highest in exclusive economic zones close to shore, particularly in areas used by both individual whales and the hydrocarbon industry. Whales potentially overlapped with different activities during each stage of their migration, which makes it difficult to implement mitigation measures over their entire range. Our results and existing population‐level data may inform delimitation of populations and actions to mitigate potential threats to whales as part of local, regional, and international management of highly migratory marine species. Cuantificación de los Movimientos de Gran Amplitud y el Traslape Potencial con Actividad Antropogénica y las Ballenas Jorobadas en el Océano Atlántico Sur  相似文献   
204.
海峡西岸地区人为源大气污染物排放特征研究   总被引:2,自引:3,他引:2  
黄成 《环境科学学报》2012,32(8):1923-1933
采用以"自下而上"为主的方法建立了2007年海峡西岸地区的人为源大气污染物排放清单.计算结果显示,海西地区人为源SO2、NOx、CO、PM10、PM2.5、VOCs和NH3排放总量分别为69.5×104、96.1×104、413.1×104、93.9×104、40.6×104、85.0×104和28.5×104t.电厂和工业燃烧设施分别占SO2排放的48%和39%,以及NOx排放的51%和25%.水泥、砖瓦等制造过程贡献了约51%的PM10排放和36%的PM2.5排放.秸秆燃烧、加油站和涂料等VOCs面源分别占到其排放总量的27%、15%和4%.NH3的主要排放源为畜禽养殖和氮肥施用等农业部门,占到总排放量的89%.海西地区的单位面积大气污染物排放量仅相当于长三角地区的25%左右,略高于全国平均水平.该地区人为源和天然源VOCs排放比重分别占56%和44%,人为源VOCs排放比重低于全国大部分地区.海西大气污染高排放地区主要集中在沿海一带,以泉州、潮汕、福州和温州等地区为主,建议"十二五"发展过程中,重点关注上述高排放地区,限制重点排放源的发展,开发低耗能、低污染的发展模式.  相似文献   
205.
Ha Long Bay in North Vietnam is characterized by karst towers and bigger islands totalling more than 3000 isles. Karst processes carved hundreds of caves out of the limestone and contributed to the formation of many enclosed and semi-enclosed saltwater lakes. Here, we report the results of a general survey of several lakes and the first data on the Hang Du I lake, a small basin devoid of any apparent communication with the surrounding sea. Hang Du I is characterized by the presence of Rhizostomeae, genus Mastigias, suggesting strong similarities with the famous lakes described from the archipelago of Palau. Among the benthic organisms sponges are the most important group. Temperature and abundance of the monsoon rains are the main factors influencing remarkable seasonal variations in physical-chemical parameters and the community structure of the lake. A thermal crisis with water temperatures up to 36 °C was recorded in September 2003. In this period, usually abundant medusae and sea anemones totally disappeared. Sponge populations showed fast growth rates in winter and spring and a partial degeneration to face the harsh conditions of the summer season. When isolated from the surrounding marine environment, the saltwater lakes share the condition of oceanic islands, representing spots of habitats surrounded by a completely different environment. The Ha Long Bay marine lakes are not easy to access, being surrounded by tropical forest, but local people usually exploit them for both fishery and oyster harvesting. There is an urgent need to develop measures of protection for these endangered and unique environments, natural laboratories that facilitate the study of evolution of marine organisms, where biodiversity has been until now totally unexplored.  相似文献   
206.
2006年12月至2007年1月(冬季)期间,对北部湾海区的生物固氮作用进行了初步研究,结果表明:当培养时间为2 h时,水体浮游生物固氮速率最高,且固氮速率随着培养时间的延长而逐渐降低。北部湾冬季固氮速率存在周日变化,8∶10~11∶10时段内固氮速率达到最高值。10 m和30 m水深在夜间仍能检测到固氮活性,这可能是浮游生物昼夜垂直移动引起的。北部湾冬季固氮速率的范围为447.5~1447.2 pmol/(L.h),固氮速率呈现出从湾内往湾外不断增加的趋势,湾口海区(B06站)的积分固氮速率为319.5μmol/(m2.d)。B06站Fe加富实验表明,添加100 nmol/L Fe能够明显促进生物固氮作用,北部湾冬季湾口海区生物固氮作用可能受到Fe限制。  相似文献   
207.
The present study aims to analyse the chemical speciation of heavy metals in relation to aerobic and anaerobic conditions. Two sediment samples (from the Gulf of Aden, Yemen) were incubated under flooded conditions. In particular, the chemical forms of Fe, Mn, Zn, Cu and Cr under the experimental conditions were studied using a sequential chemical extraction method. The pH and Eh of the suspension were measured as critical parameters controlling the fate of the metals in the environment. The results showed that the metals concentration in the different forms varied with time incubation and affected by the variation of redox potential and pH value. Also, the changes in both redox potential (Eh) and pH values had evident effects on heavy metals transformation. It is obvious that the highest redox potential affected the amount of iron and manganese in the oxides form. When the redox potential decreased to-133 and-170 mV, it caused a significant transformation of the Fe-Mn oxide form to the water-soluble and exchangeable fractions. Under anaerobic conditions, the relative percentage of all five metals including the summation of four fractions (the water-soluble and exchangeable, carbonate, oxides and organic fractions) constituted 45-60% of the total amount of iron, 33-50% for manganese, 33-63% for Zn, 63-74% for Cu and 19-43% for Cr. Both zinc and copper among water-soluble and exchangeable fraction were high at the end of incubation period, this accompanied by a significant decrease in the content of the organically bound fraction. In general, the reducing conditions were more favorable for metal bound to water soluble and exchangeable fraction.  相似文献   
208.
This paper aims to elaborate new generic DRASTIC aquifer vulnerability maps of the coastal aquifer of Metline-Ras Jebel-Raf Raf (Northeast of Tunisia) using the GIS technique, making the data analyses easier to handle and providing better capabilities of dealing with large spatial data. A similar study was carried out in 1999 in the same aquifer using a method based on the soil water balance equation to determine the net recharge parameter. Unfortunately, the lack of data in the study area made the results unsatisfactory. By applying the Williams and Kissel equation and the Rao relationship, we intend to demonstrate that we could correctly evaluate the net recharge parameter. Moreover, new data related to the aquifer hydraulic conductivity, the soil cover and the vadose zone lithology have become available, and allowed us to elaborate suitable DRASTIC maps.  相似文献   
209.
中国沿海海水入侵机制和变化规律的初步研究   总被引:4,自引:1,他引:4  
海水入侵是沿海地带不可忽视的自然灾害之一,我国沿海大致以长江口为界,长江口以南沿海主要以海水入侵河口造成的危害为主,长江口以北沿海则以海水入侵地下含水层危害较大.本文综合分析了这两类海水入侵灾害的现状、成灾原因、时空变化规律以及今后的变化趋势,并提出减灾对策与建议.  相似文献   
210.
The area between the island of Capri and Punta Campanella was investigated from June to November 2003. Punta Campanella separates the Gulf of Naples from the Gulf of Salerno and has been declared a marine protected area in 1997. The study area has a particular interesting topography, due to the presence of a sill situated at a depth of 80 m. Samples were collected by instruments carried on a mooring array (sediment trap, current meters, and temperature sensors) and by CTD cast (along transects perpendicular to the coast). We observed most important fluctuations in the temperature spectra (corresponding to the inertial oscillations period), in August. The total mass flux was 585.67 mg m-2 d-1 in the summer, while in early autumn the flux exhibited values one order of magnitude higher than in summer (1539.97 mg m-2 d-1). The main focus of this study was to understand the influence of the internal waves on the particle flux. During the autumn, in the particle flux collected, there is a strong resuspension component, and the observation that the enhanced inertial oscillations and increased sedimentation occur at the same time allows us to presume that the inertial oscillations could be one of the reasons for the resuspension process during the sampling period.  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