全文获取类型
收费全文 | 1100篇 |
免费 | 30篇 |
国内免费 | 24篇 |
专业分类
安全科学 | 52篇 |
环保管理 | 263篇 |
综合类 | 460篇 |
基础理论 | 147篇 |
环境理论 | 1篇 |
污染及防治 | 57篇 |
评价与监测 | 115篇 |
社会与环境 | 46篇 |
灾害及防治 | 13篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 12篇 |
2021年 | 24篇 |
2020年 | 54篇 |
2019年 | 12篇 |
2018年 | 14篇 |
2017年 | 31篇 |
2016年 | 37篇 |
2015年 | 25篇 |
2014年 | 49篇 |
2013年 | 41篇 |
2012年 | 38篇 |
2011年 | 74篇 |
2010年 | 41篇 |
2009年 | 86篇 |
2008年 | 60篇 |
2007年 | 64篇 |
2006年 | 60篇 |
2005年 | 37篇 |
2004年 | 33篇 |
2003年 | 52篇 |
2002年 | 47篇 |
2001年 | 29篇 |
2000年 | 41篇 |
1999年 | 35篇 |
1998年 | 25篇 |
1997年 | 13篇 |
1996年 | 13篇 |
1995年 | 21篇 |
1994年 | 8篇 |
1993年 | 19篇 |
1992年 | 13篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1977年 | 1篇 |
排序方式: 共有1154条查询结果,搜索用时 78 毫秒
971.
首先概括了城市垃圾生态工程处理的基本方法与技术,然后通过对我同垃圾现状剖析,分析了垃圾生态工程处理在我国的应用前景。 相似文献
972.
973.
Conservation planning aims to protect biodiversity by sustainng the natural physical, chemical, and biological processes within
representative ecosystems. Often data to measure these components are inadequate or unavailable. The impact of human activities
on ecosystem processes complicates integrity assessments and might alter ecosystem organization at multiple spatial scales.
Freshwater conservation targets, such as populations and communities, are influenced by both intrinsic aquatic properties
and the surrounding landscape, and locally collected data might not accurately reflect potential impacts. We suggest that
changes in five major biotic drivers—energy sources, physical habitat, flow regime, water quality, and biotic interactions—might
be used as surrogates to inform conservation planners of the ecological integrity of freshwater ecosystems. Threats to freshwater
systems might be evaluated based on their impact to these drivers to provide an overview of potential risk to conservation
targets. We developed a risk-based protocol, the Ecological Risk Index (ERI), to identify watersheds with least/most risk
to conservation targets. Our protocol combines risk-based components, specifically the frequency and severity of human-induced
stressors, with biotic drivers and mappable land- and water-use data to provide a summary of relative risk to watersheds.
We illustrate application of our protocol with a case study of the upper Tennessee River basin, USA. Differences in risk patterns
among the major drainages in the basin reflect dominant land uses, such as mining and agriculture. A principal components
analysis showed that localized, moderately severe threats accounted for most of the threat composition differences among our
watersheds. We also found that the relative importance of threats is sensitive to the spatial grain of the analysis. Our case
study demonstrates that the ERI is useful for evaluating the frequency and severity of ecosystemwide risk, which can inform
local and regional conservation planning. 相似文献
974.
975.
Brett A. Bryan John Kandulu Daniel A. Deere Monique White Jacqueline Frizenschaf Neville D. Crossman 《Journal of environmental management》2009,90(10):3122-3134
Water-borne pathogens such as Cryptosporidium pose a significant human health risk and catchments provide the first critical pollution ‘barrier’ in mitigating risk in drinking water supply. In this paper we apply an adaptive management framework to mitigating Cryptosporidium risk in source water using a case study of the Myponga catchment in South Australia. Firstly, we evaluated the effectiveness of past water quality management programs in relation to the adoption of practices by landholders using a socio-economic survey of land use and management in the catchment. The impact of past management on the mitigation of Cryptosporidium risk in source water was also evaluated based on analysis of water quality monitoring data. Quantitative risk assessment was used in planning the next round of management in the adaptive cycle. Specifically, a pathogen budget model was used to identify the major remaining sources of Cryptosporidium in the catchment and estimate the mitigation impact of 30 alternative catchment management scenarios. Survey results show that earlier programs have resulted in the comprehensive adoption of best management practices by dairy farmers including exclusion of stock from watercourses and effluent management from 2000 to 2007. Whilst median Cryptosporidium concentrations in source water have decreased since 2004 they remain above target levels and put pressure on other barriers to mitigate risk, particularly the treatment plant. Non-dairy calves were identified as the major remaining source of Cryptosporidium in the Myponga catchment. The restriction of watercourse access of non-dairy calves could achieve a further reduction in Cryptosporidium export to the Myponga reservoir of around 90% from current levels. The adaptive management framework applied in this study was useful in guiding learning from past management, and in analysing, planning and refocussing the next round of catchment management strategies to achieve water quality targets. 相似文献
976.
We integrated basic concepts from fisheries science and toxicological risk assessment to form a potential method for setting
screening-level, risk-based, site-specific water quality objectives for temperature. In summary, the proposed approach: (a)
uses temperature impacts upon specific growth as a measure of chronic (cumulative) temperature effects; (b) explicitly incorporates
the consequences of both magnitude and cumulative duration of exposures; (c) adjusts the result for local watershed conditions,
reducing the likelihood that naturally warm systems are identified as thermally polluted while helping to ensure that naturally
cool systems are closely monitored for ecologically harmful changes in thermal regime; and (d) expresses the net result both
graphically and as a risk quotient, RQ, closely analogous to that used in toxicological risk assessments. The latter yields a site-specific, risk-based water quality
objective and may serve as a straightforward decision rule for environmental managers. The method was applied to historical
data from a small British Columbia stream subject to increasing urban development pressures. We also illustrate how the technique
might be used to explore potential climatic change impacts, using coupled general circulation model predictions in conjunction
with empirical downscaling. Overall, the method and results are presented as an introduction and illustration of concept,
intended as a step toward the development of a logistically feasible risk-based approach to establishing screening-level,
site-specific water temperature objectives, and monitoring compliance, in the context of large-scale, many-site, environmental
monitoring networks. With further work, the technique offers potential to fill the gap between the temperature threshold-based
targets typically specified in regulatory guidelines, which may be hydroecologically unrealistic, and detailed biophysical
modelling, which typically is logistically infeasible in a day-to-day environmental monitoring and management context. 相似文献
977.
中国科学院农业科技领域发展路线图研究组 《生态环境》2010,19(8):1765-1770
2010年6月7日,国家主席胡锦涛在两院(中国科学院、中国工程院)院士大会上针对农业科技明确指出:构建我国生态高值农业和生物产业体系,建成农业高值转化的产业体系。本文对"生态高值农业"进行论述。所谓生态,就是要体现农业既能为社会提供安全优质的农产品又能实现农业资源的永续利用,将农业纳入可持续发展的道路;所谓高值,就是要体现农业有很高的土地产出率、投入产出率、劳动生产率。因此,"生态高值农业"是集约化经营与生态化生产有机结合的现代农业。它以健康消费需求为导向,以提高农业市场竞争力和可持续发展能力为核心,兼有高投入、高产出、高效益与可持续发展的双重特性,是转变农业增长方式、提高农业综合生产能力的集中体现。 相似文献
978.
Although many aspects of environmental accounting methodologies in food production have already been investigated, the application of environmental indicators in the fruit sector is still rare and no consensus can be found on the preferred method. On the contrary, widely diverging approaches have been taken to several aspects of the analyses, such as data collection, handling of scaling issues, and goal and scope definition. This paper reviews studies assessing the sustainability or environmental impacts of fruit production under different conditions and identifies aspects of fruit production that are of environmental importance. Four environmental assessment methods which may be applied to assess fruit production systems are evaluated, namely Life Cycle Assessment, Ecological Footprint Analysis, Emergy Analysis and Energy Balance. In the 22 peer-reviewed journal articles and two conference articles applying one of these methods in the fruit sector that were included in this review, a total of 26 applications of environmental impact assessment methods are described. These applications differ concerning e.g. overall objective, set of environmental issues considered, definition of system boundaries and calculation algorithms. Due to the relatively high variability in study cases and approaches, it was not possible to identify any one method as being better than the others. However, remarks on methodologies and suggestions for standardisation are given and the environmental burdens of fruit systems are highlighted. 相似文献
979.
Stefan Giljum Eva BurgerFriedrich Hinterberger Stephan LutterMartin Bruckner 《Resources, Conservation and Recycling》2011,55(3):300-308
Many of today's most urgent environmental problems arise from increasing volumes of worldwide production and consumption and the associated use of natural resources, including renewable and non-renewable raw materials, energy, water and land. Solid indicators to measure different dimensions of anthropogenic resource use are essential for designing appropriate policy measures for a sustainable management of these resources. Based on a brief review of the current state of the art of resource use indicators, this paper suggests a new set of complementary resource use indicators, combining existing measures for resource use. The suggested indicator set covers the core resource input categories of materials, water and land area and includes the output category of greenhouse gas emissions. This set can be applied consistently from the micro level of products and companies up to the macro level of countries and world regions. All suggested indicators take a life-cycle wide perspective on production and consumption activities. This set of indicators deals with the issue of the overall scale of the human production and consumption system. It can be regarded as the general indicator framework, based on which more specific indicators, for example, on different environmental impacts related to natural resource use, can be calculated. 相似文献
980.
Many different models can be built to explain the distributions of species. Often there is no single model that is clearly better than the alternatives, and this leads to uncertainty over which environmental factors are limiting species’ distributions. We investigated the support for different environmental factors by determining the drop in model performance when selected predictors were excluded from the model building process. We used a paired t-test over 37 plant species so that an environmental factor was only deemed significant if it consistently improved the results for multiple species. Geology and winter minimum temperatures were found to be the environmental factors with the most support, with a significant drop in model performance when either of these factors was excluded. However, there was less support for summer maximum temperature, as other environmental factors could combine to produce similar model performance. Our method of evaluating environmental factors using multiple species will not be capable of detecting predictors that are only important for one or two species, but it is difficult to distinguish these from spurious correlations. The strength of the method is that it increases inference for factors that consistently affect the distributions of many species. We discourage the assessment of models against predefined benchmarks, such as an area under the curve (AUC) of more than 0.7, as many alternative models for the same species produce similar results. Therefore, the benchmarks do not provide any indication of how the performance of the selected model compares to alternative models, and they provide weak inference to accept any selected model. 相似文献