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   235篇
  免费   7篇
  国内免费   5篇
安全科学   6篇
废物处理   11篇
环保管理   24篇
综合类   62篇
基础理论   55篇
污染及防治   62篇
评价与监测   14篇
社会与环境   10篇
灾害及防治   3篇
  2023年   4篇
  2022年   8篇
  2021年   17篇
  2020年   10篇
  2019年   6篇
  2018年   16篇
  2017年   11篇
  2016年   18篇
  2015年   9篇
  2014年   10篇
  2013年   15篇
  2012年   15篇
  2011年   18篇
  2010年   6篇
  2009年   15篇
  2008年   14篇
  2007年   9篇
  2006年   5篇
  2005年   2篇
  2004年   4篇
  2003年   2篇
  2002年   6篇
  2001年   4篇
  2000年   5篇
  1999年   6篇
  1997年   1篇
  1996年   3篇
  1994年   1篇
  1992年   1篇
  1991年   1篇
  1982年   1篇
  1981年   1篇
  1979年   1篇
  1968年   2篇
排序方式: 共有247条查询结果,搜索用时 15 毫秒
81.
82.
Understanding the processes leading to population declines in fragmented landscapes is essential for successful conservation management. However, isolating the influence of disparate processes, and dispersal in particular, is challenging. The Grey Shrike-thrush, Colluricincla harmonica, is a sedentary woodland-dependent songbird, with learned vocalizations whose incidence in suitable habitat patches falls disproportionally with decline in tree cover in the landscape. Although it has been suggested that gaps in tree cover might act as barriers to its dispersal, the species remains in many remnants of native vegetation in agricultural landscapes, suggesting that it may have responded to habitat removal and fragmentation by maintaining or even increasing dispersal distances. We quantified population connectivity of the Grey Shrike-thrush in a system fragmented over more than 120 years using genetic (microsatellites) and acoustic (song types) data. First, we tested for population genetic and acoustic structure at regional and local scales in search of barriers to dispersal or gene flow and signals of local spatial structuring indicative of restricted dispersal or localized acoustic similarity. Then we tested for effects of habitat loss and fragmentation on genetic and acoustic connectivity by fitting alternative models of mobility (isolation-by-distance [the null model] and reduced and increased movement models) across treeless vs. treed areas. Birds within -5 km of each other had more similar genotypes and song types than those farther away, suggesting that dispersal and song matching are limited in the region. Despite restricted dispersal detected for females (but not males), populations appeared to be connected by gene flow and displayed some cultural (acoustic) connectivity across the region. Fragmentation did not appear to impact greatly the dispersal of the Grey Shrike-thrush: none of the mobility models fit the genetic distances of males, whereas for females, an isolation-by-distance model could not be rejected in favor of the models of reduced or increased movement through treeless gaps. However, dissimilarities of the song types were more consistent with the model of reduced cultural connectivity through treeless areas, suggesting that fragmentation impedes song type sharing in the Grey Shrike-thrush. Our paper demonstrates that habitat fragmentation hinders important population processes in an Australian woodland bird even though its dispersal is not detectably impacted.  相似文献   
83.
Journal of Material Cycles and Waste Management - This study aimed to carry out the Life Cycle Analysis (LCA) targeting to decide the better management system for sludge from both Activated Sludge...  相似文献   
84.
ABSTRACT: Australia's ‘Landcare’ program is a community-based participatory program established by government to tackle the problem of land degradation. Landcare involves thousands of Australians working together in locally based groups, tackling problems of common concern. Government and community are now looking to ‘scale up’ the Landcare idea to a regional level. State and territory governments have moved to create regional (often watershed-based) frameworks for land management planning and resource conservation, in accordance with the concept of integrated watershed management. Growing out of the success of community involvement in Landcare, many of these approaches involve the community. However scaling up of the Landcare idea introduces problems of both time and space. There have been a number of problems experienced in the implementation of Landcare and integrated watershed management. These problems include the equitable delineation of membership on decision-making bodies; the raising of sufficient funds for program implementation; and the coordination of a diversity of governmental layers, planning processes and management programs. This paper reviews how the State of Victoria has responded to these challenges and suggests what challenges remain.  相似文献   
85.
Europe has a long history of human pressure on freshwater ecosystems. As pressure continues to grow and new threats emerge, there is an urgent need for conservation of freshwater biodiversity and its ecosystem services. However, whilst some taxonomic groups, mainly vertebrates, have received a disproportionate amount of attention and funds, other groups remain largely off the public and scientific radar. Freshwater mussels (Bivalvia, Unionida) are an alarming example of this conservation bias and here we point out six conceptual areas that need immediate and long-term attention: knowledge, threats, socioeconomics, conservation, governance and education. The proposed roadmap aims to advance research, policy and education by identifying the most pressing priorities for the short- and long-term conservation of freshwater mussels across Europe.  相似文献   
86.
Despite a significant decrease in the metallic waste emissions from an industrial site and a remediation process initiated in 2007, the Riou-Mort watershed (southwest France) still exhibits high Cd and Zn concentrations. Metal wastes have long been proven to significantly disturb aquatic communities. In this study, bioaccumulation capacities and responses to the chemical improvement of the hydrosystem were assessed for a year along the contamination gradient through the comparison of two biological models: Corbicula fluminea and periphytic biofilms, both considered as good bioindicators. Bioaccumulation results confirmed the persistence of water contamination in Corbicula fluminea and biofilms with, respectively, maximum Cd concentrations reaching 80.6 and 861.2 μg gDW(-1), and Zn concentrations 2.0 and 21.3 mg gDW(-1). Biofilms exhibited bioaccumulation in close correlation with water contamination, while Corbicula fluminea presented Cd bioaccumulation clearly regulated by water temperature and metal concentrations, affecting the ventilatory activity, as revealed by condition indices measurements. Also, a linear regression using Cd bioaccumulation and temperature () showed that below approximately 6 °C Corbicula fluminea did not appear to accumulate metals. Bioconcentration factors (BCFs) were higher in biofilms in comparison with Corbicula fluminea and showed the great accumulation capacity of suspended particulate matter in biofilms. However, bioaccumulation capacities are known to be influenced by many factors other than metal concentrations, such as temperature, water oxygenation or plankton and nutrient concentrations. Thus, this study demonstrates the power of a combined assessment using both Corbicula fluminea and biofilms as bioindicators to give a more integrated view of water quality assessment. Finally, when comparing our results with previous studies, the start of hydrosystem restoration could be shown by decreasing bioaccumulation in organisms.  相似文献   
87.
An apparently mutualistic association between Metastrongylus apri and M. pudendotectus, described on the basis of field and experimental infections of swine, is analyzed using a compartment model. Exploration of the model suggests that M. apri may be facultative mutualist and M. pudendotectus, and obligate mutualist.  相似文献   
88.
89.
人口迁徙、汇款、生活轨迹及社会应变能力   总被引:7,自引:0,他引:7  
我们认为,人口变化的方方面面,包括迁徙,都影响个人和团体的社会应变能力以及基本资源基础的可持续性.社会应变能力是应对和适应通过适当的制度调节的环境和社会变化的能力.我们调查了当今越南沿海地区人口变化、社会应变能力以及可持续发展之间关系的一个侧面:迁徙和汇款对依赖于资源的人口源区居民群的影响.利用有关生活来源的纵向运动数据,我们发现移民出境和汇款对一个逐渐形成的社会和政治范围内的应变能力有抵消作用.移民出境是与不可持续的沿海养殖业的发展同时并存的,而不是起推动作用.日益增加的经济不平等削弱了社会应变能力.同时,多种经营和收入水平的不断提高有助于应变能力的增强.  相似文献   
90.
旅游者们越来越意识到交通的负面影响(包括噪音和其他类型的污染).繁重的交通会影响旅游目的地的娱乐或其他价值.对于旅游胜地以赢利为目的的管理者来说,交通方式和参观者的满意程度及再访愿望之间的关系正越来越重要.  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