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   541篇
  免费   31篇
  国内免费   29篇
安全科学   32篇
废物处理   2篇
环保管理   249篇
综合类   129篇
基础理论   82篇
污染及防治   26篇
评价与监测   39篇
社会与环境   32篇
灾害及防治   10篇
  2024年   3篇
  2023年   4篇
  2022年   8篇
  2021年   14篇
  2020年   15篇
  2019年   12篇
  2018年   14篇
  2017年   18篇
  2016年   20篇
  2015年   13篇
  2014年   22篇
  2013年   30篇
  2012年   22篇
  2011年   39篇
  2010年   25篇
  2009年   39篇
  2008年   39篇
  2007年   41篇
  2006年   25篇
  2005年   11篇
  2004年   14篇
  2003年   13篇
  2002年   11篇
  2001年   7篇
  2000年   11篇
  1999年   9篇
  1998年   8篇
  1997年   6篇
  1996年   7篇
  1995年   7篇
  1994年   10篇
  1993年   4篇
  1992年   6篇
  1991年   7篇
  1989年   7篇
  1988年   4篇
  1987年   9篇
  1986年   8篇
  1985年   5篇
  1984年   4篇
  1983年   2篇
  1982年   5篇
  1981年   3篇
  1980年   8篇
  1979年   7篇
  1978年   4篇
  1973年   1篇
排序方式: 共有601条查询结果,搜索用时 718 毫秒
271.
Assessment of Climate Change Effects on Canada's National Park System   总被引:7,自引:0,他引:7  
To estimate the magnitude of climate change anticipated forCanada's 38 National Parks (NPs) and Park Reserves, seasonaltemperature and precipitation scenarios were constructed for 2050and 2090 using the Canadian Centre for Climate Modelling andAnalysis (CCCma) coupled model (CGCM1). For each park, we assessed impacts on physical systems, species, ecosystems andpeople. Important, widespread changes relate to marine andfreshwater hydrology, glacial balance, waning permafrost, increased natural disturbance, shorter ice season, northern andupward altitudinal species and biome shifts, and changed visitation patterns. Other changes are regional (e.g., combinedEast coast subsidence and sea level rise increase coastal erosionand deposition, whereas, on the Pacific coast, tectonic upliftnegates sea level rise). Further predictions concern individualparks (e.g., Unique fens of Bruce Peninsular NP will migratelakewards with lowered water levels, but structural regulation of Lake Huron for navigation and power generation would destroythe fens). Knowledge gaps are the most important findings. Forexample: we could not form conclusions about glacial massbalance, or its effects on rivers and fjords. Likewise, for theEast Coast Labrador Current we could neither estimate temperature and salinity effects of extra iceberg formation, nor the further effects on marine food chains, and breeding park seabirds. We recommend 1) Research on specific large knowledge gaps; 2) Climate change information exchange with protected area agencies in other northern countries; and 3) incorporating climate uncertainty into park plans and management. We discuss options for a new park management philosophy in the face of massive change and uncertainty.  相似文献   
272.
This article, a theoretical perspective based on a literature study, is a critical evaluation of SIA as part of the EIA process in South Africa against the background of international guidelines and best practices. It includes sections on the historical background of the development of SIA in South Africa, the legal status and requirements of SIA in the country, and a critical evaluation of SIA regulation in South Africa. The conclusion reached in the article is that the persistent problems of SIA practice, experienced in other parts of the world, are also evident in South Africa. Apart from institutional, financial and professional constraints, there are also serious problems associated with approach and methods. This conclusion confirms the findings of empirical studies that SIA in South Africa is neglected, that the practice of SIA in South Africa is not yet on a sound footing, and that it does not receive the professional attention it deserves in a country beset by enormous social challenges. To conclude the article recommendations are made to improve the level of SIA practice in South Africa, and the possible significance of this national case study for international practice is indicated.  相似文献   
273.
Detecting trends in biological attributes is central to many stream monitoring programs; however, understanding how natural variability in environmental factors affects trend results is not well understood. We evaluated the influence of antecedent streamflow and sample timing (covariates) on trend estimates for fish, invertebrate, and diatom taxa richness and biological condition from 2002 to 2012 at 51 sites distributed across the conterminous United States. A combination of linear regression and Kendall‐tau test for trends were used to evaluate covariate influence on trend estimates. Adjusting for covariates changed the magnitude of trend estimates in two‐thirds of cases on average by 21%, most often reducing the estimated magnitude of the trend. Additionally, covariates influenced the interpretation of over one‐third of trend estimates by either strengthening or weakening trends after adjustment. Our findings clearly indicate that antecedent streamflow and sample timing influences trend estimates and subsequent interpretation. Accounting for covariates during trend analysis will enhance stream monitoring programs by providing a better understanding and interpretation of estimated changes in biological endpoints at monitored sites. Failure to account for antecedent streamflow and sample timing may lead to mischaracterization of a trend and/or misunderstanding of potential causes.  相似文献   
274.
The National Flood Interoperability Experiment is a research collaboration among academia, National Oceanic and Atmospheric Administration National Weather Service, and government and commercial partners to advance the application of the National Water Model for flood forecasting. In preparation for a Summer Institute at the National Water Center in June‐July 2015, a demonstration version of a near real‐time, high spatial resolution flood forecasting model was developed for the continental United States. The river and stream network was divided into 2.7 million reaches using the National Hydrography Dataset Plus geospatial dataset and it was demonstrated that the runoff into these stream reaches and the discharge within them could be computed in 10 min at the Texas Advanced Computing Center. This study presents a conceptual framework to connect information from high‐resolution flood forecasting with real‐time observations and flood inundation mapping and planning for local flood emergency response.  相似文献   
275.
The paper describes a software system capable of formulating alternative optimal Municipal Solid Wastes (MSWs) management plans, each of which meets a set of constraints that may reflect selected objections and/or wishes of local communities. The objective function to be minimized in each plan is the sum of the annualized capital investment and annual operating cost of all transportation, treatment and final disposal operations involved, taking into consideration the possible income from the sale of products and any other financial incentives or disincentives that may exist. For each plan formulated, the system generates several reports that define the plan, analyze its cost elements and yield an indicative profile of selected types of installations, as well as data files that facilitate the geographic representation of the optimal solution in maps through the use of GIS. A number of these reports compare the technical and economic data from all scenarios considered at the study area, municipality and installation level constituting in effect sensitivity analysis. The generation of alternative plans offers local authorities the opportunity of choice and the results of the sensitivity analysis allow them to choose wisely and with consensus.The paper presents also an application of this software system in the capital Region of Attica in Greece, for the purpose of developing an optimal waste transportation system in line with its approved waste management plan. The formulated plan was able to: (a) serve 113 Municipalities and Communities that generate nearly 2 million t/y of comingled MSW with distinctly different waste collection patterns, (b) take into consideration several existing waste transfer stations (WTS) and optimize their use within the overall plan, (c) select the most appropriate sites among the potentially suitable (new and in use) ones, (d) generate the optimal profile of each WTS proposed, and (e) perform sensitivity analysis so as to define the impact of selected sets of constraints (limitations in the availability of sites and in the capacity of their installations) on the design and cost of the ensuing optimal waste transfer system. The results show that optimal planning offers significant economic savings to municipalities, while reducing at the same time the present levels of traffic, fuel consumptions and air emissions in the congested Athens basin.  相似文献   
276.
In light of the increasing mandate for greater efficiency in conservation of natural reserves such as national parks, the present study suggests educational approaches as a tool to achieve conservation purposes. Currently, the management of human–wildlife interactions is dominated by regulatory strategies, but considerable potential exists for environmental education to enhance knowledge in the short run and to prompt attitude change in the long run. A framework for conservation based on both traditional regulatory- and behavior-oriented strategies was proposed whereby the level of knowledge that park visitors have acquired comprises an obvious outcome and establishes a basis upon which the effectiveness of regulatory- and behavior-based regimes could be assessed. The perceptions regarding park-related issues of two distinct visitor groups (locals and nonlocals) are summarized from a survey undertaken in Vikos-Aoos national park. The findings suggest a superficial knowledge for certain concepts but little profound understanding of the content of such concepts, indicating that knowledge-raising efforts should go a long way towards establishing a positive attitude for the resource. Visitors' poor knowledge of the park's operation regulation contest the efficiency of the presently dominant regulatory management regime. While geographical distances did not appear to significantly differentiate knowledge between the two groups, wilderness experience (as certified by visits to other parks) was proved to be an impetus for generating substantial learner interest in critical park issues among nonlocal visitors. School education and media were found to be significant knowledge providers.  相似文献   
277.
The paper gives an account of the development and implementation of a stakeholder management framework at Ream National Park, Cambodia. Firstly, the concept of stakeholder is reviewed in management and in conservation literatures. Secondly, the context in which the stakeholder framework was implemented is described. Thirdly, a five-step methodological framework is suggested: (1) stakeholder analysis, (2) stakeholder mapping, (3) development of generic strategies and workplan, (4) presentation of the workplan to stakeholders, and (5) implementation of the workplan. This framework classifies stakeholders according to their level of influence on the project and their potential for the conservation of natural resources. In a situation characterized by conflicting claims on natural resources, park authorities were able to successfully develop specific strategies for the management of stakeholders. The conclusion discusses the implications of the Ream experience and the generalization of the framework to other protected areas.  相似文献   
278.
Globally, municipalities are tackling climate adaptation and resilience planning. Urban green space has crucial biophysical buffering capacities, but also affects social interactions and human well-being. This paper considers the social dimension of urban green space, through an assessment focused on park use, function, and meanings, and compares results to categories of cultural ecosystem services. We develop a mixed-method approach for assessment of uses and social meanings of parkland and pilot this method in 2140 acres of parkland in waterfront neighborhoods surrounding New York City’s Jamaica Bay, an area heavily affected by Hurricane Sandy. This method combines observation of human activities and signs of prior human use with structured interviews of park users. We find that urban parkland is a crucial form of ‘nearby nature’ that provides space for recreation, activities, socialization, and environmental engagement and supports place attachment and social ties. We show that parks, through their use by and interactions with humans, are producing vital cultural ecosystem services that may help to strengthen social resilience. Certain services were more easily detectable than others via our assessment technique, including recreation, social relations, and sense of place. The assessment method was designed to be spatially explicit, scalable, and replicable; natural resource managers engaged in park management and/or resilience planning could apply this method across individual sites, in particular districts—such as vulnerable waterfront areas, and citywide. This study demonstrates a way in which cultural ecosystem services and an understanding of social meaning could be incorporated into park management and resilience planning.  相似文献   
279.
Tourism is the way we understand the world: tourists travel in an increasingly mediated environment in which ubiquitous promotional material and other popular artifacts employ stunning images and romantic travel narratives to describe local environments. Tourist texts “sell” local landscapes to entice visitors, employing an environmental aesthetic that urges travel. With its mission to “explore the planet,” the National Geographic Society contributes to this tourist aesthetic. This essay examines three special issues on Africa simultaneously published by the National Geographic Society: its official journal, National Geographic, and its sister magazines, National Geographic Traveler, and National Geographic Adventure. The photographic images and travel narratives in these tourist texts produce an environmental aesthetic that positions the traveler at the center of these environments. This essay first analyzes how National Geographic constructs Africa's environmental landscapes. These magazines depict Africa as a vast desert plain, a wilderness theme park, and a part of the global scenery. The second part of the analysis examines how National Geographic locates the tourist in these environments. I discuss how National Geographic positions the tourist as protagonist, expert, and hero of Africa's environment. In the conclusions, I argue this environmental aesthetic renders Africa invisible through anthropocentric distance, and I discuss the need for more critical readings of tourist discourse.  相似文献   
280.
Multi-tenure reserve networks aim to connect areas managed for biodiversity conservation across public and private land and address the impacts of fragmentation on both biotic and social systems. The operation and function of Australian multi-tenure reserve networks as perceived by their land managers was investigated. Overall, the conservation of natural assets was the most frequently reported primary reason for involvement in a network. The perceived aims of the respective networks largely reflected the response identified for involvement and management. Over 88% of managers considered their involvement in multi-tenure reserve networks to be a positive or very positive experience. A lack of resources and time for management were considered major limitations of these networks. The majority (80%) of private land managers within networks were willing to be included in a national reserve system of conservation lands. As the Australian National Reserve System currently incorporates mostly public land, these findings have important and potentially positive implications for a greater role for protected private land.  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