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 125 毫秒
821.
人工湿地组合工艺在风景区污水处理中的应用 总被引:1,自引:0,他引:1
文章从污水生态处理、中水回用以及污水处理与景观建设相结合等几方面,详细介绍了人工湿地组合工艺这一领先技术在风景区污水处理工程中的应用。重点阐述了世博园污水的排放特性、组合工艺的组成及工程建设内容,并提出人工湿地组合工艺的几大特点及技术应用时需注意的问题。 相似文献
822.
823.
Ecological literacy is founded upon knowledge and understanding about how the ecological systems of the Earth function and support life. A widespread concern that levels of ecological literacy within many contemporary human communities are inadequate to enable effective decision-making about sustainable ways of living led to a rigorous and carefully designed assessment of over 1000 South Australian adults from diverse sectors including industry, government, nongovernment, business and community organisations. This assessment tested for local and global knowledge, including an understanding of the interconnection of natural systems with human society. Quantitative analyses revealed significant relationships between scores and a range of socio-demographic characteristics. Scores varied significantly with gender, age, education, employment, place of growing up and time spent in South Australia (SA). Highest average scores were found in males, middle-age groups, the most highly educated, those with science-related educational backgrounds, those working in environment-related fields, those who grew up in small town environments rather than in large towns or cities and in those who had spent more than 10 years in SA. These findings contribute to a broader study of factors associated with ecologically literate individuals and groups within the western and industrialised adult community of SA. They form a valuable foundation on which to build efforts to further understand and develop ecological literacy within our citizenry and governing bodies. 相似文献
824.
Contamination of soils by heavy metals is of rising concern in many cities in China undergoing rapid urbanization. Here, we evaluate the severity of soil contamination by four heavy metals (arsenic, chromium, copper, and lead) at 146 urban and suburban sites within the city of Xiamen, Fujian, China. A multivariate regression model was proposed and developed to simulate heavy metals accumulation in urban and suburban soils, to identify the concentration and spatial distribution of heavy metals in soils, and to assess ecological risks by 2020. Results showed that, overall, Xiamen soils should be subject to low ecological risks due to heavy metals contamination by 2020, the ecological risks for urban soils were greater than suburban soils, nearly half of Xiamen soils are at moderate ecological risks, and many suburban soils experience low ecological risks. The methods demonstrate the potential to predict future ecological risks from heavy metals contamination which could inform pollution prevention and control measures. 相似文献
825.
In the ecological network analysis (ENA) of complex flow food webs the assumption is often made that the models characterizing the flows and stocks of ecosystems occur in a steady state where inflows equals outflows. An assessment of the system indices derived from ENA of six balanced and unbalanced system models, respectively, indicate to differences between indices. The aggregation of highly articulated flow models into models with fewer compartments also has drastic effects on the system metrics, particularly on the information indices. 相似文献
826.
Based on the thermodynamic concept of exergy as a unified measure for environmental resources and economic products, a framework for systems assessment is presented for ecological economies. With a typical systems diagram devised for a general ecological economy with four arm fluxes for free local natural resources, purchased economic investment, environmental impact and economic yield, system indices of the renewability index, exergy yield ratio, exergy investment ratio, environmental resource to yield ratio, system transformity and environmental stress index are defined for a congregated systems ecological assessment with essential implications to sustainability. As a detailed case study to the Chinese agriculture from 1980 to 2000 with cropping, forestry, stockbreeding and fishery sectors, extensive exergy account and systems assessment are carried out with emphasis on annual and structural variations against social political transitions. For the overall agriculture as a congregated ecological stage, the value of the system transformity is found around 10, the typical value for the general ecological hierarchy as well devised by Odum associated with Lindeman's Tenth Law. 相似文献
827.
Missing covariate values in linear regression models can be an important problem facing environmental researchers. Existing
missing value treatment methods such as Multiple Imputation (MI), the EM algorithm and Data Augmentation (DA) have the assumption that both observed and unobserved data come from the same distribution,
most commonly a multivariate normal or a conditionally multivariate normal family. These methods do try to incorporate the
missing data mechanism and rely on the assumption of Missing At Random (MAR). We present a DA method which does not rely on
the MAR assumption and can model missing data mechanisms and covariate structure. This method utilizes the Gibbs Sampler as
a tool for incorporating these structures and mechanisms. We apply this method to an ecological data set that relates fish
condition to environmental variables. Notice that the presented DA method detects relationships that are not detected when
other missing data methods are employed.
相似文献
Edward L. BooneEmail: |
828.
Ingrid Hillmer Penelope van Reenen Jrg Imberger Tamar Zohary 《Ecological modelling》2008,218(1-2):49-59
Phytoplankton concentration in Lake Kinneret (Israel) has varied up to 10-fold in space and time, with horizontal patches ranging from a couple of kilometres to a basin scale. Previous studies have used a 1D model to reproduce the temporal evolution of physical and biogeochemical variables in this lake. The question that arises then is how appropriate is a 1D approach to represent the dynamic of a spatially heterogeneous system, where there are non-linear dependencies between variables. Field data, a N-P-Z model coupled to both a 1D and a 3D hydrodynamic model, a 1D diffusion-reaction equation and scaling analysis are used to understand the role of spatial variability, expressed as phytoplankton patchiness, in the modelling of primary production. The analysis and results are used to investigate the effect of horizontal variability in the forcing and in the free mechanisms that affect the growth of patterns. The study shows that the use of averaged properties in a 1D approach may produce misleading results in the presence of localised patches, in terms of both concentration and composition of phytoplankton. The reason lies in the fact that the calibration process of ecological parameters in the 1D model appears to be site and process specific. That is, it depends on the pattern's characteristics and the underlying physical processes causing them. And this is a critical point for the success of numerical simulations under spatial variability. In this study, it is also shown that a length scale based on diffusion and growth rate of phytoplankton could be used as a criterion to assess the appropriateness of the 1D assumption. 相似文献
829.
Increasing dietary specialization is an inherently risky strategy because it increases a species’ vulnerability to resource
depletion. However, risks associated with dietary specialization may be offset by increased performance when feeding on preferred
prey. Although rarely demonstrated, highly specialized species are expected to outperform generalists when feeding on their
preferred prey, whereas generalists are predicted to have more similar performance across a range of different prey. To test
this theory, we compared the growth rates of two obligate coral-feeding butterflyfishes (Chaetodon trifascialis and Chaetodon plebeius) maintained on exclusive diets of preferred vs nonpreferred prey. In the field, C. trifascialis was the most specialized species, feeding almost exclusively on just one coral species, Acropora hyacinthus. C. plebeius meanwhile, was much less specialized, but fed predominantly on Pocillopora damicornis. During growth experiments, C. trifascialis grew fastest when feeding on A. hyacinthus and did not grow at all when feeding on less preferred prey (P. damicornis and Porites cylindrica). C. plebeius performed equally well on both A. hyacinthus and P. damicornis (its preferred prey), but performed poorly when feeding on P. cylindrica. Both butterflyfishes select coral species that maximize juvenile growth, but contrary to expectations, the more specialized
species (C. trifascialis) did not outperform the generalist species (C. plebeius) when both consumed their preferred prey. Increased dietary specialization, therefore, appears to be a questionable strategy,
as there was no evidence of any increased benefits to offset increases in susceptibility to disturbance. 相似文献
830.
Terraces are traditional engineered ecosystems that affect the hydro-geological equilibrium, slope stability, and local communities. The aims of this paper are (i) identifying environmental factors that affect terrace stability in the Amalfi Coast, (ii) defining agriculturalists’ observations on environmental changes within that system and (iii) exploring potentiality of these observations to better define conservation strategies. All available data on physical and ecological factors recognized to affect the terrace system were collected and analyzed. Interviews were conducted with agriculturalists to obtain long-term observations on environmental factors that interact with this system. Landslides are more frequent where rainfall is high and during winter. Fires have an uneven annual distribution, with higher frequency during summers. Agriculturalists detailed complex interactions among environmental factors, economic elements, and terraces. These observations represent a valuable resource for defining causes and effects of abandonment and for better addressing conservation strategies.