全文获取类型
收费全文 | 213篇 |
免费 | 4篇 |
国内免费 | 4篇 |
专业分类
安全科学 | 10篇 |
废物处理 | 4篇 |
环保管理 | 33篇 |
综合类 | 55篇 |
基础理论 | 54篇 |
污染及防治 | 35篇 |
评价与监测 | 12篇 |
社会与环境 | 11篇 |
灾害及防治 | 7篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 2篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 13篇 |
2015年 | 9篇 |
2014年 | 5篇 |
2013年 | 12篇 |
2012年 | 9篇 |
2011年 | 12篇 |
2010年 | 5篇 |
2009年 | 11篇 |
2008年 | 19篇 |
2007年 | 8篇 |
2006年 | 12篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 7篇 |
2002年 | 13篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1996年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有221条查询结果,搜索用时 31 毫秒
161.
Ella Louise Bell 《组织行为杂志》1990,11(6):415-415
162.
Ella Louise Bell 《组织行为杂志》1990,11(6):459-477
This study explores the bicultural life experience of black career-oriented women. Seventy-one women participated in a larger study on the life experiences of black women. Of this sample, 21 (29 per cent) of the women were identified as being career-oriented. Findings reveal that the women perceive themselves as living in two distinct cultural contexts, one black the other one white. The women compartmentalize the various components of their lives in order to manage the bicultural dimensions. In addition, they tend to have highly complex life structures to embrace both cultural contexts. 相似文献
163.
Sandy?Burden Subharup?GuhaEmail author Geoff?Morgan Louise?Ryan Ross?Sparks Linda?Young 《Environmental and Ecological Statistics》2005,12(4):427-448
The recently funded Spatial Environmental Epidemiology in New South Wales (SEE NSW) project aims to use routinely collected
data in NSW Australia to investigate risk factors for various chronic diseases. In this paper, we present a case study focused
on the relationship between social disadvantage and ischemic heart disease to highlight some of the methodological challenges
that are likely to arise. 相似文献
164.
Carlson PR Yarbro LA Madley K Arnold H Merello M Vanderbloemen L McRae G Durako MJ 《Environmental monitoring and assessment》2003,81(1-3):393-408
We examined the response of demographic, morphological, and chemical parameters of turtle grass (Thalassia testudinum), to much-higher-than-normal rainfall associated with an El Niño event in the winter of 1997–1998. Up to 20 inches of added rain fell between December 1997 and March 1998, triggering widespread and persistent phytoplankton blooms along the west coast of Florida. Water-column chlorophyll concentrations estimated from serial SeaWiFS imagery were much higher during the El Niño event than in the previous or following years, although the timing and magnitude of phytoplankton blooms varied among sites. Seagrass samples collected in 1997, 1998, and 1999 provided an excellent opportunity to test the responsiveness of Thalassia to decline and subsequent improvement of water quality and clarity in four estuaries. Using a scoring technique based on temporal responsiveness, spatial consistency, and statistical strength of indicators, we found that several morphological parameters (Thalassia shoot density, blade width, blade number, and shoot-specific leaf area) were responsive and consistent measures of light stress. Some morphological parameters, such as rhizome apex density, responded to declines and subsequent improvement in water clarity, but lacked the statistical discriminating power necessary to be useful indicators. However, rhizome sugar, starch, and the total carbohydrate concentrations also exhibited spatially and temporally consistent variation as well as statistical strength. Because changes in shoot density, as well as water clarity, affect rhizome carbohydrate levels, a composite metric based on Thalassia shoot density and rhizome carbohydrate levels together is probably more useful than either parameter alone as an indicator of seagrass health. 相似文献
165.
The Canary Islands are home to a guild of endemic, threatened bird-pollinated plants. Previous work has suggested that these
plants evolved floral traits as adaptations to pollination by flower specialist sunbirds, but subsequently, they appear to
have co-opted generalist passerine birds as sub-optimal pollinators. To test this idea, we carried out a quantitative study
of the pollination biology of three of the bird-pollinated plants, Canarina canariensis (Campanulaceae), Isoplexis canariensis (Veronicaceae) and Lotus berthelotii (Fabaceae), on the island of Tenerife. Using colour vision models, we predicted the detectability of flowers to bird and
bee pollinators. We measured pollinator visitation rates, nectar standing crops as well as seed-set and pollen removal and
deposition. These data showed that the plants are effectively pollinated by non-flower specialist passerine birds that only
occasionally visit flowers. The large nectar standing crops and extended flower longevities (>10 days) of Canarina and Isoplexis suggests that they have evolved a bird pollination system that effectively exploits these low frequency non-specialist pollen
vectors and is in no way sub-optimal. Seed set in two of the three species was high and was significantly reduced or zero
in flowers where pollinator access was restricted. In L. berthelotii, however, no fruit set was observed, probably because the plants were self-incompatible horticultural clones of a single
genet. We also show that, while all three species are easily detectable for birds, the orange Canarina and the red Lotus (but less so the yellow-orange Isoplexis) should be difficult to detect for insect pollinators without specialised red receptors, such as bumblebees. Contrary to
expectations if we accept that the flowers are primarily adapted to sunbird pollination, the chiffchaff (Phylloscopus canariensis) was an effective pollinator of these species. 相似文献
166.
Olivier Le Curieux-Belfond Louise Vandelac Joseph Caron Gilles-Éric Séralini 《Environmental Science & Policy》2009,12(2):170-189
Many genetically modified plants have been developed, and four of them (soya, maize, cotton, and colza) representing more than 99% of commercial crops, are widely distributed, mainly in the United States and in America [ISAAA, 2006. Report on global status on biotech/GM crops, Brief 35. International Service for the Acquisition of Agri-biotech Applications organization, US]. Yet all over the world policy is still in development in regard to authorization of modified plants and modified and/or cloned animals for food or feed and for their environmental release. The most advanced animal commercial projects concern various fish species, more easy to genetically transform, notably because conception and development take place in water and easy access to numerous eggs. A request for authorization to introduce genetically modified (GM) salmon onto the market has been presented to the Food and Drug Administration (FDA) of the US. In the interim, questions have been raised concerning the impacts of transgenic salmon, modified for productivity, on aquaculture, wildlife, ecosystems and on human health. Herein we review these scientific studies and sanitary, environmental, social and economic arguments. This paper analyses current gaps in the knowledge of the impacts of transgenic fish and proposes legislation orientations necessary for environmental and sanitary protection, should the marketing of animal genetically modified organisms (GMOs) be authorized. 相似文献
167.
Robert Fish Michael Winter David M. Oliver David Chadwick Theresa Selfa A. Louise Heathwaite Chris Hodgson 《Environmental Science & Policy》2009,12(3):281-296
This paper examines some of the theoretical and methodological issues arising from the process of conceptualising and eliciting values for environmental risk in the context of heterogeneous expert knowledge. Drawing on the experience of a recent research project examining the relationship between livestock farming systems and microbial watercourse pollution the paper reflects critically upon efforts to develop an interdisciplinary assessment of the factors that may affect the loss of potential pathogens from agricultural land to water courses as the basis for targeting high risk fields and farms. The paper describes the procedures for designing the natural and cultural parameters that surround microbial risks and the issues that are raised for making whole system assessments workable based on contrasting and unstable systems of disciplinary insight. Situated within claims about the need for generating reliable and widely applicable assessments of environmental risk the paper suggests that interdisciplinary working raises important issues about the role of ‘uncertain’ knowledge in the management of ‘known’ risks. 相似文献
168.
During early development, oviparous fish species must use finite lipid and fatty acid (FA) reserves for both catabolism and structural components. In cold environments, developing fish have the additional constraint of maintaining membrane fluidity for metabolic efficiency (homeoviscous adaptation), resulting in further demand on lower melting point FAs like n-3 polyunsaturated fatty acids (PUFAs). To examine whether marine fish embryos physiologically adapt to changing temperature environments, we incubated Pacific cod (Gadus macrocephalus) eggs at 5 temperatures (0, 2, 4, 6, and 8 °C) in the laboratory and sampled them repeatedly during development to measure changes in lipid/FA composition. Pacific cod embryos increased n-3 PUFA content during the egg stage in all temperature treatments, with the possible exception of 0 °C, where poor survival and hatch success limited our ability for continued sampling. At the beginning of the hatch cycle, free-swimming embryos shifted from lipogenesis to lipid catabolism. The rates of lipogenesis and catabolism were temperature dependent, and the distinct increase in unsaturated fatty acids at temperatures <8 °C was consistent with homeoviscous adaptation theory. However, with the possible exception of embryos at 0 °C, the relative amounts of essential fatty acids (e.g., EPA, DHA, AA) were conserved in a similar manner across incubation temperatures. Collectively, these data suggest Pacific cod are capable of homeoviscous adaptation but cannot tolerate temperatures approaching 0 °C despite their possible ability to biosynthesize PUFAs from other energetic sources. 相似文献
169.
Colonization studies may function as natural experiments and have the potential of addressing important questions about community assembly. We studied colonization for a guild of epiphytic lichens in a former treeless heathland area of 170 km2 in southwest Norway. We investigated if epiphytic lichen species richness and composition on aspen (Populus tremula) trees corresponded to a random draw of lichen individuals from the regional species pool. We compared lichen communities of isolated young (55-120 yr) and old (140-200 yr) forest patches in the heathland area to those of aspen forest in an adjacent reference area that has been forested for a long time. All thalli (lichen bodies) of 32 selected lichen species on trunks of aspen were recorded in 35 aspen sites. When data for each site category (young, old, and reference) were pooled, we found the species richness by rarefaction to be similar for reference sites and old sites, but significantly lower for young sites. The depauperated species richness of young sites was accompanied by a skew in species composition and absence of several species that were common in the reference sites. In contrast, genetic variation screened with neutral microsatellite markers in the lichen species Lobaria pulmonaria showed no significant differences between site categories. Our null hypothesis of a neutral species assembly in young sites corresponding to a random draw from the regional species pool was rejected, whereas an alternative hypothesis based on differences in colonization capacity among species was supported. The results indicate that for the habitat configuration in the heathland area (isolated patches constituting < 0.4% of the area) lichen communities may need a colonization time of 100-150 yr for species richness to level off, but given enough time, isolation will not affect species richness. We suggest that this contradiction to expectations from classical island equilibrium theory results from low extinction rates. 相似文献
170.
Using circuit theory to model connectivity in ecology, evolution, and conservation 总被引:13,自引:0,他引:13
Connectivity among populations and habitats is important for a wide range of ecological processes. Understanding, preserving, and restoring connectivity in complex landscapes requires connectivity models and metrics that are reliable, efficient, and process based. We introduce a new class of ecological connectivity models based in electrical circuit theory. Although they have been applied in other disciplines, circuit-theoretic connectivity models are new to ecology. They offer distinct advantages over common analytic connectivity models, including a theoretical basis in random walk theory and an ability to evaluate contributions of multiple dispersal pathways. Resistance, current, and voltage calculated across graphs or raster grids can be related to ecological processes (such as individual movement and gene flow) that occur across large population networks or landscapes. Efficient algorithms can quickly solve networks with millions of nodes, or landscapes with millions of raster cells. Here we review basic circuit theory, discuss relationships between circuit and random walk theories, and describe applications in ecology, evolution, and conservation. We provide examples of how circuit models can be used to predict movement patterns and fates of random walkers in complex landscapes and to identify important habitat patches and movement corridors for conservation planning. 相似文献