全文获取类型
收费全文 | 763篇 |
免费 | 27篇 |
国内免费 | 5篇 |
专业分类
安全科学 | 79篇 |
废物处理 | 52篇 |
环保管理 | 138篇 |
综合类 | 117篇 |
基础理论 | 149篇 |
环境理论 | 1篇 |
污染及防治 | 180篇 |
评价与监测 | 36篇 |
社会与环境 | 29篇 |
灾害及防治 | 14篇 |
出版年
2023年 | 4篇 |
2022年 | 14篇 |
2021年 | 11篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 22篇 |
2017年 | 28篇 |
2016年 | 25篇 |
2015年 | 21篇 |
2014年 | 24篇 |
2013年 | 67篇 |
2012年 | 41篇 |
2011年 | 55篇 |
2010年 | 36篇 |
2009年 | 28篇 |
2008年 | 37篇 |
2007年 | 42篇 |
2006年 | 43篇 |
2005年 | 35篇 |
2004年 | 26篇 |
2003年 | 28篇 |
2002年 | 26篇 |
2001年 | 15篇 |
2000年 | 8篇 |
1999年 | 11篇 |
1998年 | 4篇 |
1997年 | 10篇 |
1996年 | 10篇 |
1995年 | 12篇 |
1994年 | 21篇 |
1993年 | 10篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1968年 | 1篇 |
1960年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有795条查询结果,搜索用时 31 毫秒
761.
Modeling obsolete computer stock under regional data constraints: An Atlanta case study 总被引:1,自引:0,他引:1
Nancey Green Leigh Matthew J. Realff Ning Ai Steven P. French Catherine L. Ross Bert Bras 《Resources, Conservation and Recycling》2007,51(4):847-869
In this paper, we report on our efforts to develop a research framework that can be used to quantify waste flows for different geographical areas in the face of limited waste data availability. We demonstrate this framework in our case study of obsolete computers in the Atlanta metropolitan area. We develop computer obsolescence rates at the national metropolitan level, and couple this data with economic information at the census tract level to generate product inventory estimates (PIE) of the stock of obsolete computers from both business and household sectors in the Atlanta metropolitan area. We seek to improve the accuracy of waste flow estimates for specific geographic areas over those of previous studies, provide an easily replicable and cost effective methodology, highlight the ensuing spatial implications for collection and recycling systems using GIS, and demonstrate the potential economic benefits from diverting electronic wastes within a region. The modeling framework we have developed is intended to be applicable to other regions and to other medium range durable goods discarded by households, businesses, or obtained from buildings. 相似文献
762.
/ Regional resource use planning relies on key regional stakeholder groups using and having equitable access to appropriate social, economic, and environmental information and assessment tools. Decision support systems (DSS) can improve stakeholder access to such information and analysis tools. Regional resource use planning, however, is a complex process involving multiple issues, multiple assessment criteria, multiple stakeholders, and multiple values. There is a need for an approach to DSS development that can assist in understanding and modeling complex problem situations in regional resource use so that areas where DSSs could provide effective support can be identified, and the user requirements can be well established. This paper presents an approach based on the soft systems methodology for identifying DSS opportunities for regional resource use planning, taking the Central Highlands Region of Queensland, Australia, as a case study. 相似文献
763.
Bottom sediment and suspended sediment samples from Hamilton Harbour (western Lake Ontario) and from a major tributary were profiled using polycyclic aromatic hydrocarbons (PAH) and thia-arenes as source apportionment tracers. Ratios of selected PAH and ratios of monomethyl and dimethyl/ethyl dibenzothiophenes to the parent dibenzothiophenes were calculated. Thia-arene and PAH profiles of Standard Reference Material SRM 1649 (urban dust/organics), SRM 1650 (diesel), SRM 1597 (coal tar), Hamilton coal tar and a composite Hamilton air particulate sample provided source sample data. The gas chromatography-mass spectrometry (GC-MS) chromatograms of all sample extracts were dominated by homocyclic PAH but interpretation of PAH profiles with respect to source was difficult. In contrast, thia-arene analyses revealed more distinct differences in profiles of samples collected in different areas of the harbour, including the tributary. These results indicated that areas of coal tar-contaminated sediment are potential contributors to the overall contaminant burden of sediments and suspended sediments in Hamilton Harbour. These data also indicated that contaminants related to mobile combustion sources were entering the harbour via a major tributary. 相似文献
764.
Hydrology, roadway traffic conditions, and atmospheric deposition are three essential data categories for the planning and
implementation of highway-runoff monitoring and characterization programs. Causal variables pertaining to each data category
could be site specific but have been shown to correlate with runoff pollutant loads. These data categories were combined to
derive statistical relationships for characterization and prioritization of the respective pollutant loads at highway runoff
sites. Storm runoff data of total suspended solids (TSS), total dissolved solid (TDS), chemical oxygen demand (COD), total
Kjeldahl nitrogen (TKN) and total phosphorus (TP) collected from three highway sites in Charlotte, North Carolina, USA, were
used to illustrate the development of site-specific highway-runoff pollutant loading models. This unified methodology provides
a basis for initial assessment of the pollutant-constituent loads from highway runoff using hydrologic component variables.
Improved reliability is achievable when additional traffic and/or atmospheric component variables are incorporated into the
basic hydrologic regression model. In addition, operational guidance is suggested for implementing highway-runoff monitoring
programs that are subject to sampling and resources constraints. 相似文献
765.
766.
Landscape of fear influences the relative importance of consumptive and nonconsumptive predator effects 总被引:1,自引:0,他引:1
Predators can initiate trophic cascades by consuming and/or scaring their prey. Although both forms of predator effect can increase the overall abundance of prey's resources, nonconsumptive effects may be more important to the spatial and temporal distribution of resources because predation risk often determines where and when prey choose to forage. Our experiment characterized temporal and spatial variation in the strength of consumptive and nonconsumptive predator effects in a rocky intertidal food chain consisting of the predatory green crab (Carcinus maenas), an intermediate consumer (the dogwhelk, Nucella lapillus), and barnacles (Semibalanus balanoides) as a resource. We tracked the survival of individual barnacles through time to map the strength of predator effects in experimental communities. These maps revealed striking spatiotemporal patterns in Nucella foraging behavior in response to each predator effect. However, only the nonconsumptive effect of green crabs produced strong spatial patterns in barnacle survivorship. Predation risk may play a pivotal role in determining the small-scale distribution patterns of this important rocky intertidal foundation species. We suggest that the effects of predation risk on individual foraging behavior may scale up to shape community structure and dynamics at a landscape level. 相似文献
767.
Although birds and mammals play important roles in several mechanisms hypothesized to maintain plant diversity in species-rich habitats, there have been few long-term, community-level tests of their importance. We excluded terrestrial birds and mammals from fourteen 6 x 7.5 m plots in Australian primary tropical rain forest and compared recruitment and survival of tree seedlings annually over the subsequent seven years to that on nearby open plots. We re-censused a subset of the plots after 13 years of vertebrate exclusion to test for longer-term effects. After two years of exclusion, seedling abundance was significantly higher (74%) on exclosure plots and remained so at each subsequent census. Richness was significantly higher on exclosure plots from 1998 to 2003, but in 2009 richness no longer differed, and rarefied species richness was higher in the presence of vertebrates. Shannon's diversity and Pielou's evenness did not differ in any year. Vertebrates marginally increased density-dependent mortality and recruitment limitation, but neither effect was great enough to increase richness or diversity on open plots relative to exclosure plots. Terrestrial vertebrates significantly altered seedling community composition, having particularly strong impacts on members of the Lauraceae. Overall, our results highlight that interactions between terrestrial vertebrates and tropical tree recruitment may not translate into strong community-level effects on diversity, especially over the short-term, despite significant impacts on individual species that result in altered species composition. 相似文献
768.
Bénédicte Ritt Catherine Pierre Olivier Gauthier Frank Wenzhöfer Antje Boetius Jozée Sarrazin 《Marine Biology》2011,158(6):1187-1210
The Nile Deep-Sea Fan (NDSF) is located on the passive continental margin off Egypt and is characterized by the occurrence
of active fluid seepage such as brine lakes, pockmarks and mud volcanoes. This study characterizes the structure of faunal
assemblages of such active seepage systems of the NDSF. Benthic communities associated with reduced, sulphidic microhabitats
such as sediments and carbonate crusts were sampled by remotely operated vehicles during two cruises in 2006 (BIONIL) and
2007 (MEDECO). Environmental conditions and biological factors including family-level faunal composition, density and diversity
were measured at local and regional scales. Significant differences were detected at different spatial scales: (1) the fauna
of reduced habitats differed substantially in activity, diversity and biomass from the non-seep environment at similar water
depth, (2) cold seep microhabitats showed differences in community structure and composition related to substratum type as
well as to the intensity and location of fluid emissions. 相似文献
769.
Patricia Prado Catherine J. Collier Javier Romero Teresa Alcoverro 《Marine Biology》2011,158(7):1473-1482
Herbivory is now recognized as an important structuring agent in seagrass meadows but the attack pattern and tissue damage
of consumers are highly variable. Nutritional preferences of herbivores and/or easy access to resources may cause differences
in biomass loss among tissues that damage the plant in functionally distinctive ways. The two main Mediterranean herbivores,
the fish Sarpa salpa (L.) and the sea urchin Paracentrotus lividus (Lmk.), remove higher amounts of intermediate and external shoot leaves, respectively. To test whether this selective feeding
can have different consequences on the allocation patterns of nutrient within plants, we simulated the effect of both herbivores
by clipping external and intermediate leaves (plus unclipped controls) of Posidonia oceanica (L.) and we measured plant tolerance in terms of shoot growth and leaf nutrient supply to new tissue using isotopic markers.
As expected, control treatments displayed high carbon and nutrient supply from external leaves (83% of the total 15N and 84% of the total 13C incorporated by the shoot). When subjected to clipping, the remaining leaves enhanced carbon and nitrogen supply compared
with the control by 16% of N and 36% of C—in the intermediate clipping—and by over 100% of N and 200% of C—in the external
clipping—to compensate for the nutrient lost. However, only in the case of fish herbivory (intermediate clipping), enhanced
supply alone was able to fully compensate for the nutrient losses. In contrast, this mechanism is not completely effective
when external leaves are clipped (urchin herbivory). Yet, the consequences of this nutrient loss under sea urchin herbivory
are not apparent from the nutrient content of the new tissue, suggesting that there are other sources of nitrogen income (uptake
or reallocation from rhizomes). Our study does not only confirm the tolerance of P. oceanica to herbivory, but also constitutes the first evidence of leaf-specific, compensatory nutrient supply in seagrasses. 相似文献
770.
Katherine A. Margolis Catherine Y. Kingsley Westerman Kathleen M. Kowalski-Trakofler 《Safety Science》2011,49(3):522-530
Refuge chambers are new devices for underground coal mines that provide approximately 96 h of breathable air, water, food, and supplies in the event of an emergency where miners are unable to escape. Researchers at the National Institute for Occupational Safety and Health (NIOSH) developed a training program to prepare miners for what to expect psychologically and physiologically inside of a refuge chamber. The field tests of this training revealed that it was received very positively by miners and helped impart realistic views about the physical discomforts and psychological stresses of being inside a refuge chamber. 相似文献