全文获取类型
收费全文 | 596篇 |
免费 | 26篇 |
国内免费 | 8篇 |
专业分类
安全科学 | 18篇 |
废物处理 | 13篇 |
环保管理 | 129篇 |
综合类 | 116篇 |
基础理论 | 172篇 |
环境理论 | 3篇 |
污染及防治 | 110篇 |
评价与监测 | 33篇 |
社会与环境 | 24篇 |
灾害及防治 | 12篇 |
出版年
2023年 | 11篇 |
2022年 | 9篇 |
2021年 | 20篇 |
2020年 | 27篇 |
2019年 | 26篇 |
2018年 | 27篇 |
2017年 | 29篇 |
2016年 | 31篇 |
2015年 | 36篇 |
2014年 | 23篇 |
2013年 | 50篇 |
2012年 | 38篇 |
2011年 | 56篇 |
2010年 | 31篇 |
2009年 | 21篇 |
2008年 | 30篇 |
2007年 | 33篇 |
2006年 | 30篇 |
2005年 | 21篇 |
2004年 | 10篇 |
2003年 | 17篇 |
2002年 | 10篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有630条查询结果,搜索用时 31 毫秒
91.
Dóra B. Huszár Rasmus S. Larsen Sarah Carlsen Jacobus J. Boomsma Jes Søe Pedersen 《Behavioral ecology and sociobiology》2014,68(11):1859-1870
Ant supercolonies (large networks of interconnected nests) represent the most extreme form of multi-queen breeding (polygyny) and have been found across ant lineages, usually in specific long-term stable populations. Many studies on the genetic population structure and demography of ant supercolonies have been done in recent decades, but they have lacked multicolonial control patches with separated colonies headed by a single or few queens so the origin of the supercolonial trait syndrome has remained enigmatic. Here, we set out to compare sympatric supercolonial and multicolonial patches in two natural Danish populations of the common red ant Myrmica rubra. We used DNA microsatellites to reconstruct genetic colony/population structure and obtained morphological and density measurements to estimate life history and ecology covariates. We found that supercolonies in both populations completely dominated their patches whereas colonies in multicolonial patches coexisted with other ant species. Supercolony patches had very low genetic differentiation between nests, negligible relatedness within nests, and lower inbreeding than multicolonial patches, but there were no significant morphological differences. One population also had nests that approached true outbred monogyny with larger workers and males but smaller queens than in the two other social nest types. Our results suggest that once smaller colonies start to adopt additional queens, they also gain the potential to ultimately become supercolonial when the habitat allows rapid expansion through nest budding. This is relevant for understanding obligate polygyny in ants and for appreciating how and why introduced North American populations of M. rubra have recently become invasive. 相似文献
92.
93.
Social media and disasters: a functional framework for social media use in disaster planning,response, and research 总被引:1,自引:0,他引:1
J. Brian Houston Joshua Hawthorne Mildred F. Perreault Eun Hae Park Marlo Goldstein Hode Michael R. Halliwell Sarah E. Turner McGowen Rachel Davis Shivani Vaid Jonathan A. McElderry Stanford A. Griffith 《Disasters》2015,39(1):1-22
A comprehensive review of online, official, and scientific literature was carried out in 2012–13 to develop a framework of disaster social media. This framework can be used to facilitate the creation of disaster social media tools, the formulation of disaster social media implementation processes, and the scientific study of disaster social media effects. Disaster social media users in the framework include communities, government, individuals, organisations, and media outlets. Fifteen distinct disaster social media uses were identified, ranging from preparing and receiving disaster preparedness information and warnings and signalling and detecting disasters prior to an event to (re)connecting community members following a disaster. The framework illustrates that a variety of entities may utilise and produce disaster social media content. Consequently, disaster social media use can be conceptualised as occurring at a number of levels, even within the same disaster. Suggestions are provided on how the proposed framework can inform future disaster social media development and research. 相似文献
94.
Employing in-depth, elite interviews, this empirical research contributes to understanding the dynamics among policy windows,
policy change, and organizational learning. First, although much of the research on agenda setting—how issues attract enough
attention that action is taken to address them—has been conducted at the national scale, this work explores the subnational,
regional scale. With decentralization, regional-scale environmental decision-making has become increasingly important. Second,
this research highlights the role of policy windows and instances of related organizational learning identified by natural
resources managers. Having practitioners identify focusing events contrasts with the more typical approach of the researcher
identifying a particular focusing event or events to investigate. A focusing event is a sudden, exceptional experience that,
because of how it leads to harm or exposes the prospect for great devastation, is perceived as the impetus for policy change. 相似文献
95.
Swetnam RD Owen Mountford J Manchester SJ Broughton RK 《Journal of environmental management》2004,71(1):79-93
This paper explores whether the introduction of an agri-environmental scheme has altered the course of long-term trends in plant species abundance in the Somerset Levels and Moors Environmentally Sensitive Area (ESA), UK. A semi-quantitative approach has been taken which integrates disparate but important historical datasets relating to flora and land management with more contemporary digital information. Species datasets from four time periods throughout the 20th century have been collated within a Geographic Information System and analysed with respect to ancillary data relating to elevation, under-drainage and ESA designation. Qualitative reconstruction of the historical ecology of this internationally important area of lowland wet grassland showed that a steady decline in abundance and extent of key components of the flora had already started by 1900. Analysis of historical under-drainage records dating from 1940s to 1980s showed a clear link between the length of time an area had been under-drained and the subsequent diversity of flora recorded in later surveys. In addition, the relative persistence of the rarer components of the wetland flora between surveys in 1980 and 1997 was related to the spatial pattern of under-drainage on the site since 1940. When overall species diversity was compared before and after ESA designation (1980-1997) there was some evidence of an increase in the number of species present and their spatial extent. The historical dataset provided useful contextual information with respect to species trends and allowed the interpretation of contemporary datasets to be placed within a longer timeframe. This pilot study using 18 species gives some evidence that long-established trends in species decline in the Somerset Levels and Moors ESA are starting to be reversed. 相似文献
96.
97.
98.
Sarah Ewing 《Local Environment》1996,1(3):259-276
Australia's 'Landcare' programme is a community-based, participatory programme established by government, to tackle the problem of land degradation. It has been hailed by some as the world's most imaginative sustainable development policy. In light of the agreements reached at the Rio Earth Summit, particularly Agenda 21, the experience of established programmes such as Landcare may be useful to those beginning to grapple with the call for greater community involvement. This paper explores briefly the presentation and enactment of ideas of 'community' and 'ownership' in the Landcare programme and finds that, contrary to the rhetoric, community 'ownership' of Landcare is, in practice, ambiguous. 相似文献
99.
100.
This paper summarizes those factors that have contributed to the degradation of the mangroves in El Salvador, and examines the implications of proposed changes in property rights to the mangroves for poor coastal communities. Current patterns of extraction and conversion in the mangrove ecosystem in El Salvador can be viewed through an entitlement lens that confers property right upon some actors, for certain uses, and denies them to others. Unfortunately, the present system of laws and regulations that governs resource use in the mangroves is contradictory and confusing. A number of laws currently are active that give entirely different directives about the use and transformation of the ecosystem. The rational and sustainable management of the mangroves cannot be secured without a redefinition of entitlement rights. This redefinition of entitlements, however, should take into account the needs of those whose livelihoods are intimately connected to the health of the ecosystem. 相似文献