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71.
Andrew J. Collins Kasi Bharath Vegesana Michael J. Seiler Patrick O’Shea Prasanna Hettiarachchi Frederic McKenzie 《The Environmentalist》2013,33(3):427-439
Many mathematical programs have been developed over the past 50 years to aid agricultural experts and other farming decision-makers. The application of these mathematical programs has seen limited success because their development has focused on mathematical theory as opposed to the requirements needed for application. This paper describes the development of two mathematical programs that were designed to integrate with a visualization simulation that aids a nontraditional group of agricultural decision-makers: illiterate Sri Lankan subsistence farmers. The simulation was designed to help these illiterate farmers make business decisions about their crop selection choices which, in turn, will help them develop their business plans required for obtaining bank micro-loans. This paper’s focus is on the use of linear programming as a potential tool to demonstrate the benefits of crop diversification and rotation to the farmer based on various available crop types. It also highlights the issues using such an approach. 相似文献
72.
Lyndhurst Collins 《Journal of Environmental Planning and Management》1996,39(3):333-356
Social conscience and public opinion have promoted a popular belief that all recycling is good for the environment. Planning policies and environmental legislation have been and continue to be influenced in part by this belief. Economic and political factors have been important especially in terms of developing recovery programmes and systems for collecting waste material. This is particularly true for paper products, for which there is now a whole range of arbitrary set recycling targets in most western countries. Paper products are different from all other major recycled products in that they are made from a renewable resource and, as recovered waste, it has alternative uses such as energy recovery. In the framework of mounting empirical evidence the aim of the paper is to question the validity of social conscience as a raison d'etre for increasing the rate of recycling paper products. Forests, which are the primary renewable resource, have important implications for a whole range of economic, social and climatic issues, especially global warming. There is an urgent need to take stock of these issues for both planning and managing the environment. 相似文献
73.
74.
Woody encroachment decreases diversity across North American grasslands and savannas 总被引:2,自引:0,他引:2
Woody encroachment is a widespread and acute phenomenon affecting grasslands and savannas worldwide. We performed a meta-analysis of 29 studies from 13 different grassland/savanna communities in North America to determine the consequences of woody encroachment on plant species richness. In all 13 communities, species richness declined with woody plant encroachment (average decline = 45%). Species richness declined more in communities with higher precipitation (r2 = 0.81) and where encroachment was associated with a greater change in annual net primary productivity (ANPP; r2 = 0.69). Based on the strong positive correlation between precipitation and ANPP following encroachment (r2 = 0.87), we hypothesize that these relationships occur because water-limited woody plants experience a greater physiological and demographic release as precipitation increases. The observed relationship between species richness and ANPP provides support for the theoretical expectation that a trade-off occurs between richness and productivity in herbaceous communities. We conclude that woody plant encroachment leads to significant declines in species richness in North American grassland/savanna communities. 相似文献
75.
Hispanic residents suffer disproportionately from exposure to toxic pollution hazards, but little is known about why some Hispanic residents live in high-risk neighbourhoods while others are protected from similar risks. This study uses comparative interview-based methods to further understanding of Hispanic people’s residential decision-making and their associated exposures to hazardous air pollutants (HAPs) in the Miami Metropolitan Statistical Area (Florida), which is home to one of the most diverse Hispanic populations in the U.S. We use 22 in-depth interviews conducted with Hispanic householders living at high and low risk to HAPs, selected from a larger representative phone survey of 650 local residents. For Hispanic households at high risk, economic constraints, family ties, desiring a central location, a sense of community, and comfort in a shared culture contributed to their residences in high risk locations. In contrast, protective factors for Hispanic households living at low risk included the desire to live in an ethnically diverse setting, the ease of finding service work, and preferring environmental amenities and exclusivity. Findings demonstrate that there are considerable differences in factors shaping residential decision-making of low- and high-risk Hispanic residents, but that all were influenced by economic, socio-cultural, and environmental considerations to varying degrees. 相似文献
76.
Situating Hazard Vulnerability: People’s Negotiations with Wildfire Environments in the U.S. Southwest 总被引:1,自引:1,他引:0
This article is based on a multimethod study designed to clarify influences on wildfire hazard vulnerability in Arizona’s
White Mountains, USA. Findings reveal that multiple factors operating across scales generate socially unequal wildfire risks.
At the household scale, conflicting environmental values, reliance on fire insurance and firefighting institutions, a lack
of place dependency, and social vulnerability (e.g., a lack of financial, physical, and/or legal capacity to reduce risks)
were found to be important influences on wildfire risk. At the regional-scale, the shift from a resource extraction to environmental
amenity-based economy has transformed ecological communities, produced unequal social distributions of risks and resources,
and shaped people’s social and environmental interactions in everyday life. While working-class locals are more socially vulnerable
than amenity migrants to wildfire hazards, they have also been more active in attempting to reduce risks in the aftermath
of the disastrous 2002 Rodeo-Chediski fire. Social tensions between locals and amenity migrants temporarily dissolved immediately
following the disaster, only to be exacerbated by the heightened perception of risk and the differential commitment to hazard
mitigation displayed by these groups over a 2-year study period. Findings suggest that to enhance wildfire safety, environmental
managers should acknowledge the environmental benefits associated with hazardous landscapes, the incentives created by risk
management programs, and the specific constraints to action for relevant social groups in changing human-environmental context. 相似文献
77.
Metal transport in a stream polluted by acid mine drainage--The Afon Goch, Anglesey, UK 总被引:4,自引:0,他引:4
Boult S Collins DN White KN Curtis CD 《Environmental pollution (Barking, Essex : 1987)》1994,84(3):279-284
Sampling of the Afon Goch over a 14-month period revealed maximum dissolved Fe, Al, Mn, Cu and Zn concentrations of 259, 167, 49, 60 and 42 mg dm(-3), respectively, and pH as low as 2.3, making it one of the most metal- and acid-contaminated streams in the UK. The river produces particulates by precipitation of ferrihydrite, due to the entry of near-neutral tributary waters, under all discharge conditions. Consequently, metal transport in this stream is dominated by processes different from those in less contaminated streams. The stream acts as a sink for contaminants, except under high discharge, when accumulated metals are flushed from the system. The implications of these observations for the monitoring and management of streams polluted by acid mine drainage are discussed. 相似文献
78.
Making literature reviews more reliable through application of lessons from systematic reviews
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Review articles can provide valuable summaries of the ever‐increasing volume of primary research in conservation biology. Where findings may influence important resource‐allocation decisions in policy or practice, there is a need for a high degree of reliability when reviewing evidence. However, traditional literature reviews are susceptible to a number of biases during the identification, selection, and synthesis of included studies (e.g., publication bias, selection bias, and vote counting). Systematic reviews, pioneered in medicine and translated into conservation in 2006, address these issues through a strict methodology that aims to maximize transparency, objectivity, and repeatability. Systematic reviews will always be the gold standard for reliable synthesis of evidence. However, traditional literature reviews remain popular and will continue to be valuable where systematic reviews are not feasible. Where traditional reviews are used, lessons can be taken from systematic reviews and applied to traditional reviews in order to increase their reliability. Certain key aspects of systematic review methods that can be used in a context‐specific manner in traditional reviews include focusing on mitigating bias; increasing transparency, consistency, and objectivity, and critically appraising the evidence and avoiding vote counting. In situations where conducting a full systematic review is not feasible, the proposed approach to reviewing evidence in a more systematic way can substantially improve the reliability of review findings, providing a time‐ and resource‐efficient means of maximizing the value of traditional reviews. These methods are aimed particularly at those conducting literature reviews where systematic review is not feasible, for example, for graduate students, single reviewers, or small organizations. 相似文献
79.
The distribution and diet of juvenile (<750 mm) Patagonian toothfish are described from four annual trawl surveys (2003–2006)
around the island of South Georgia in the Atlantic sector of the Southern Ocean. Recruitment of toothfish varies inter-annually,
and a single large cohort dominated during the four years surveyed. Most juveniles were caught on the Shag Rocks shelf to
the NW of South Georgia, with fish subsequently dispersing to deeper water around both the South Georgia and Shag Rocks shelves.
Mean size of juvenile toothfish increased with depth of capture. Stomach contents analysis was conducted on 795 fish that
contained food remains and revealed that juvenile toothfish are essentially piscivorous, with the diet dominated by notothenid
fish. The yellow-finned notothen, Patagonotothen guntheri, was the dominant prey at Shag Rocks whilst at South Georgia, where P. guntheri is absent, the dominant prey were Antarctic krill and notothenid fish. The diet changed with size, with an increase in myctophid
fish and krill as toothfish grow and disperse. The size of prey also increased with fish size, with a greater range of prey
sizes consumed by larger fish. 相似文献
80.
The geographical distributions, seasonal variations in numerical abundance and biomass (mg C m-3) of the predators of the holoplankton of the Bristol Channel, between November 1973 and February 1975, are described. The predator numbers and biomass were dominated by the chaetognath Sagitta elegans Verrill. This species represented 96% of the holoplankton carnivore biomass in the outer, seaward region of the Channel and 60% in the inner region; the remainder being ctenophores. The maximum numerical abundance of S. elegans occurred in September at 129 individuals m-3 (18 mg C m-3). Juveniles (<5 mm) reached maximum numbers of 55 individuals m-3 during June, August and September, demonstrating the reproductive activity of the population. The peak numbers were probably the result of the development of two major generations over the 90 d period from mid-June to mid-September. The tentaculate ctenophores were represented by Pleurobrachia pileus (O. F. Müller). The highest abundance was 81 individuals m-3 (3.0 mg C m-3) at a single site in July in the South Central Channel. However, June was the only month when the ctenophores dominated the carnivore biomass in all regions of the Channel; thereafter, S. elegans was more abundant. Reproduction of the ctenophore occurred from April to September, with juveniles reaching maximum abundance in June at 12 individuals m-3. The estimated food demand of the population in May for the outer region of the Channel was approximately 31% of the daily production of copepods. When the population reached its peak abundance in June, the estimated food requirement outstripped the daily production of copepods and a decline in both the prey and predator standing stocks was observed. Similar estimations were derived for the inner region of the Channel. S. elegans increased from a standing stock of 0.038 mg C m-3 in March to 6.35 mg C m-3 in September. Estimates of the copepod production compared with the derived demand of the chaetognath population showed that the decline in the copepods in the late summer was the result of feeding by this predator. The holoplankton carnivore population was approximately 66% of the copepod standing stock for the 10 mo period November 1973 to September 1974 in the outer region of the Channel and 45% of that in the inner region. The carnivores formed the greater part of the total holoplankton biomass from September through the winter months to February, suggesting a predator-dominated community. 相似文献