全文获取类型
收费全文 | 251篇 |
免费 | 41篇 |
国内免费 | 42篇 |
专业分类
安全科学 | 78篇 |
废物处理 | 5篇 |
环保管理 | 69篇 |
综合类 | 89篇 |
基础理论 | 44篇 |
污染及防治 | 7篇 |
评价与监测 | 29篇 |
社会与环境 | 11篇 |
灾害及防治 | 2篇 |
出版年
2024年 | 1篇 |
2023年 | 8篇 |
2022年 | 10篇 |
2021年 | 14篇 |
2020年 | 12篇 |
2019年 | 23篇 |
2018年 | 18篇 |
2017年 | 14篇 |
2016年 | 22篇 |
2015年 | 15篇 |
2014年 | 17篇 |
2013年 | 22篇 |
2012年 | 19篇 |
2011年 | 12篇 |
2010年 | 15篇 |
2009年 | 11篇 |
2008年 | 17篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 10篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 3篇 |
1996年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有334条查询结果,搜索用时 15 毫秒
91.
Long-term changes of fish biotic integrity in the Sanmenxia Wetland,North China,since the 1950 s were assessed using the fish index of biological integrity(FIBI). The water and sediment quality was evaluated by the water quality index(WQI) and sediment pollution index(SPI). The results showed that FIBI continuously decreased from 46 to 20 during the past 5 decades,which indicated that the fish community state shifted from fair to very poor conditions,and damming by itself did not affect the fish biotic integrity. At the same time,WQI fell from 83 to 44.1,and SPI increased from 0.99 to 2.14 since the 1960 s,resulting from fast regional socio-economic development and insufficient wastewater treatment. Correlation analysis suggested that water quality significantly affected biotic integrity(r = 0.867,p 〈 0.05) through direct effects on the fish community. As a representative example of many wetlands in North China,our study clearly demonstrated that the biological integrity was degraded,induced both by water quality deterioration and sediment pollution,further driven by the contradiction between rapid development of regional economy and lagging development of sewage treatment facilities,which were thought to be the main factor responsible for the degradation of biological integrity. 相似文献
92.
The functional role of differentiation with respect to local population density, expression of responses to the presence of other individuals, and body weight has been analyzed from an ecoenergetic standpoint with consideration of known mathematical laws. The results indicate that increased variation in these parameters (i.e., their higher diversity) improves the efficiency of energy flow through the animal population: the input of energy increases, while its expenditures decrease. The greatest effect is achieved when the population is divided into alternative modal groups. 相似文献
93.
Relations of fish community composition to environmental variables in streams of central Nebraska,USA 总被引:1,自引:0,他引:1
Nine sites on streams in the Platte River Basin in central Nebraska were sampled as part of the US Geological Survey's National Water-Quality Assessment Program during 1993–1994. A combination of canonical correspondence analysis and an index of biotic integrity determined from fish community data produced complementary evaluations of water-quality conditions. Results of the canonical correspondence analysis were useful in showing which environmental variables were significant in differentiating fish communities at the nine sites. Five environmental variables were statistically significant in the analysis. Median specific conductance of water samples collected at a site accounted for the largest amount of variability in the species data. Although the percentage of the basin as cropland was not the first variable chosen in a forward selection process, it was the most strongly correlated with the first ordination axis. A rangeland-dominated site was distinguished from all others along that axis. Median orthophosphate concentration of samples collected in the year up to the time of fish sampling was most strongly correlated with the second ordination axis. The index of biotic integrity produced results that could be interpreted in terms of the relative water quality between sites. Sites draining nearly 100% cropland had the lowest scores for two individual metrics of the index of biotic integrity that were related to species tolerance. Effective monitoring of water quality could be achieved by coupling methods that address both the ecological components of fish communities and their statistical relationships to environmental factors. 相似文献
94.
95.
Derek B. Booth James R. Karr Sally Schauman Christopher P. Konrad Sarah A. Morley Marit G. Larson Stephen J. Burges 《Journal of the American Water Resources Association》2004,40(5):1351-1364
ABSTRACT: Successful stream rehabilitation requires a shift from narrow analysis and management to integrated understanding of the links between human actions and changing river health. At study sites in the Puget Sound lowlands of western Washington State, landscape, hydrological, and biological conditions were evaluated for streams flowing through watersheds with varying levels of urban development. At all spatial scales, stream biological condition measured by the benthic index of biological integrity (B‐IBI) declined as impervious area increased. Impervious area alone, however, is a flawed surrogate of river health. Hydrologic metrics that reflect chronic altered streamflows, for example, provide a direct mechanistic link between the changes associated with urban development and declines in stream biological condition. These measures provide a more sensitive understanding of stream basin response to urban development than do treatment of each increment of impervious area equally. Land use in residential backyards adjacent to streams also heavily influences stream condition. Successful stream rehabilitation thus requires coordinated diagnosis of the causes of degradation and integrative management to treat the range of ecological stressors within each urban area, and it depends on remedies appropriate at scales from backyards to regional storm water systems. 相似文献
96.
On Developing Bioindicators for Human and Ecological Health 总被引:5,自引:0,他引:5
Risk assessors and risk managersgenerally either examine ecological health (usingbioindicators) or human health (using biomarkers ofexposure or effect). In this paper we suggest thatit is possible and advantageous to developbioindicators that can be used to assess exposureand effect for both human and non-human receptors. We describe the characteristics of suitablebioindicators for both human and ecological health,using mourning doves (Zenaida macroura),raccoons (Procyon lotor), and bluefish (Pomatomus saltatrix) as examples, and list thegeneral characteristics of other species that wouldmake them useful indicators for assessing both humanand ecological health. Bioindicators can beused cross-sectionally to assess the status ofecosystems and risk as well as longitudinally formonitoring changes or evaluating remediation. Forboth human and ecological risk assessment, there arethree sets of characteristics to consider whenselecting bioindicators: biological relevance,methodological relevance, and societal relevance. An indicator which fails to fulfill these is notlikely to be considered cost-effective and is likelyto be abandoned. The indicator should be readilymeasured and must measure an important range ofimpacts. For long-term support of a bioindicator,the indicator should be easily understood, and becost effective. We suggest that bioindicators thatcan also be used for both ecological and humanhealth risk assessment are optimal. 相似文献
97.
Edith?T.?Lammerts?Van?Bueren Paul?C.?StruikEmail author 《Journal of Agricultural and Environmental Ethics》2005,18(5):479-493
In addition to obviating the use of synthetic agrochemicals and emphasizing farming in accordance with agro-ecological guidelines, organic farming acknowledges the integrity of plants as an essential element of its natural approaches to crop production. For cultivated plants, integrity refers to their inherent nature, wholeness, completeness, species-specific characteristics, and their being in balance with their (organically farmed) environment, while accomplishing their “natural aim.” We argue that this integrity of plants has ethical value, distinguishing integrity of life, plant-typic integrity, genotypic integrity, and phenotypic integrity. We have developed qualitative criteria to ethically evaluate existing practices and have applied these criteria to assess whether current plant breeding and propagation techniques violate the integrity of crop plants. This process has resulted in a design of a holistic, scientific approach of organic plant breeding and seed production. Our evaluation has met considerable criticism from mainstream (crop) scientists. We respond to the following questions: (1). Can ethics be incorporated into objective crop sciences? (2). What is the nature of the intrinsic value of plants in organic farming? We argue that criteria to take integrity into account can only be assessed from a holistic perspective and we show that a holistic approach is needed to design such ethical notions in a consistent way. The ethical notions have been further elaborated by formulating human responsibility and respect towards crop plants. Responsibility and respect can only be shown by providing crop plants the right to be nurtured and to express natural behavior at all levels of integrity. 相似文献
98.
Assessing Ecological Integrity of Ozark Rivers to Determine Suitability for Protective Status 总被引:3,自引:0,他引:3
Preservation of extraordinary natural resources, protection of water quality, and restoration of impaired waters require a strategy to identify and protect least-disturbed streams and rivers. We applied two objective, quantitative methods to determine stream ecological integrity of headwater reaches of 10 Ozark rivers, 5 with Wild and Scenic River federal protective status. Thirty-four variables representing macroinvertebrate and fish assemblage characteristics, in-stream habitat, riparian vegetation, water quality, and watershed attributes were quantified for each river and analyzed using two multivariate approaches. The first approach, cluster and discriminant analyses, identified two groups of river with only one variable (% forested watershed) reliably distinguishing groups. Our second approach employed ordinal scaling to compare variables for each river to conceptually ideal conditions that were developed as a composite of optimal attributes among the 10 rivers. The composite distance of each river from ideal was then calculated using a unidimensional ranking technique. Two rivers without Wild and Scenic River designation ranked highest relative to ideal (highest ecological integrity), and two others, also without designation, ranked most distant from ideal (lowest ecological integrity). Fish density, number of intolerant fish species, and invertebrate density were influential biotic variables for scaling. Contributing physical variables included riparian forest cover, water nitrate concentration, water turbidity, percentage of forested watershed, percentage of private land ownership, and road density. These methods provide a framework for refinement and application in other regions to facilitate the process of establishing least-disturbed reference conditions and identifying rivers for protection and restoration. 相似文献
99.
采用生物行为传感器监测青鳉鱼在重金属铜暴露下的行为数据,分析不同暴露浓度(20、10、5、1和0.1 TU)下青鳉鱼的行为响应。20、10、5、1和0.1 TU的暴露浓度下青鳉鱼对重金属污染的行为反应模式符合环境胁迫阈值模型,且不同浓度梯度重金属对青鳉鱼产生不同的行为毒性效应。利用重金属作用下青鳉鱼的行为变化来研究重金属环境胁迫导致的生物行为响应机制,从而得到重金属暴露下生物行为的实时变化过程和趋势,可对水环境生态系统质量进行综合评价。 相似文献
100.
Development of a Bird Integrity Index: Measuring Avian Response to Disturbance in the Blue Mountains of Oregon, USA 总被引:1,自引:0,他引:1
Bryce SA 《Environmental management》2006,38(3):470-486
The Bird Integrity Index (BII) presented here uses bird assemblage information to assess human impacts to 28 stream reaches
in the Blue Mountains of eastern Oregon. Eighty-one candidate metrics were extracted from bird survey data for testing. The
metrics represented aspects of bird taxonomic richness, tolerance or intolerance to human disturbance, dietary preferences,
foraging techniques, and nesting strategies that were expected to be positively or negatively affected by human activities
in the region. To evaluate the responsiveness of each metric, it was plotted against an index of reach and watershed disturbance
that included attributes of land use/land cover, road density, riparian cover, mining impacts, and percent area in clearcut
and partial-cut logging. Nine of the 81 candidate bird metrics remained after eliminating unresponsive and highly correlated
metrics. Individual metric scores ranged from 0 to 10, and BII scores varied between 0 and 100. BII scores varied from 78.6
for a minimally disturbed, reference stream reach to 30.4 for the most highly disturbed stream reach. The BII responded clearly
to varying riparian conditions and to the cumulative effects of disturbances, such as logging, grazing, and mining, which
are common in the mountains of eastern Oregon. This BII for eastern Oregon was compared to an earlier BII developed for the
agricultural and urban disturbance regime of the Willamette Valley in western Oregon. The BII presented here was sensitive
enough to distinguish differences in condition among stream riparian zones with disturbances that were not as obvious or irreversible
as those in the agricultural/urban conditions of western Oregon. 相似文献