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61.
David F. Preusser William A. Leaf Karen B. DeBartolo Richard D. Blomberg Marvin M. Levy 《Journal of Safety Research》1982,13(2):45-55
Right-Turn-on-Red (RTOR), in its “Western” version allows motorists to turn right on a red signal after stopping and yielding, unless specifically prohibited by a sign. The objective of this study was to determine the effect of Western RTOR on pedestrian and bicycle accidents in selected jurisdictions adopting the rule in the mid-1970s. The results showed significant increases in pedestrian and bicyclist accidents involving right-turning vehicles at signalized locations following the introduction of Western RTOR. These increases were: 40 % for pedestrians and 82 % for bicycles in New York State; 107 % for pedestrians and 72 % for bicycles in Wisconsin; 57 % for pedestrians and 80 % for bicycles in Ohio; and 82 % for pedestrians in New Orleans. Analysis of police accident reports suggested that drivers stopped for a red light are looking left for a gap in traffic and do not see pedestrians and bicyclists coming from their right. Countermeasure research and development was recommended to deal with this well defined problem which involves between 1 % and 3 % of all pedestrian and bicycle accidents. 相似文献
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Shaun K. Wilson Nicholas A. J. Graham Rebecca Fisher Jan Robinson Kirsty Nash Karen Chong‐Seng Nicholas V. C. Polunin Riaz Aumeeruddy Rodney Quatre 《Conservation biology》2012,26(6):995-1004
Disturbance plays an important role in structuring marine ecosystems, and there is a need to understand how conservation practices, such as the designation of Marine Protected Areas (MPAs), facilitate postdisturbance recovery. We evaluated the association of MPAs, herbivorous fish biomass, substrate type, postdisturbance coral cover, and change in macroalgal cover with coral recovery on the fringing reefs of the inner Seychelle islands, where coral mortality after a 1998 bleaching event was extensive. We visually estimated benthic cover and fish biomass at 9 sites in MPAs where fishing is banned and at 12 sites where fishing is permitted in 1994, 2005, 2008, and 2011. We used analysis of variance to examine spatial and temporal variations in coral cover and generalized additive models to identify relations between coral recovery and the aforementioned factors that may promote recovery. Coral recovery occurred on all substrate types, but it was highly variable among sites and times. Between 2005 and 2011 the increase in coral cover averaged 1%/year across 21 sites, and the maximum increase was 4%/year. However, mean coral cover across the study area (14%) remained at half of 1994 levels (28%). Sites within MPAs had faster rates of coral recovery than sites in fished areas only where cover of macroalgae was low and had not increased over time. In MPAs where macroalgae cover expanded since 1998 there was no recovery. Where coral was recovering on granite reefs there was a shift in relative prevalence of colony life‐form from branching to encrusting species. This simplification of reef structure may affect associated reef fauna even if predisturbance levels of coral cover are attained. Efecto de la Expansión de Macroalgas y Áreas Marinas Protegidas sobre la Recuperación de Coral Después de una Perturbación Climática 相似文献
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Boundaries and Corridors as a Continuum of Ecological Flow Control: Lessons from Rivers and Streams 总被引:4,自引:0,他引:4
Abstract: Landscape boundaries and corridors are areas of small spatial extent relative to their large effects on ecological flows. The trend in ecological literature is to treat corridors and boundaries as separate phenomena on the landscape. This approach, however, misses a fundamental aspect they have in common: their strong influence on ecological flows. Corridors and boundaries exist at opposite ends of a permeability gradient, differing in their effects on rates and direction of flow. The position of landscape structures along this permeability gradient depends on attributes of both the flow and of the structure itself. We discuss boundaries and corridors in terms of mover specificity, scale, and effects on different levels of ecological organization, using rivers and streams to illustrate our points. We predict which structures will act as boundaries or corridors and at what spatial and temporal scales they are likely to be relevant. Considering the function of landscape structures across the boundary-corridor continuum will provide researchers and managers with a more complete, holistic viewpoint and will allow better strategies to attain conservation goals. 相似文献
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MarÍA JOSÉ Ruiz‐López Natalia Gañan José Antonio Godoy Ana Del Olmo Julian Garde Gerardo Espeso Astrid Vargas Fernando Martinez Eduardo R. S. Roldán Montserrat Gomendio 《Conservation biology》2012,26(6):1121-1129
The relation among inbreeding, heterozygosity, and fitness has been studied primarily among outbred populations, and little is known about these phenomena in endangered populations. Most researchers conclude that the relation between coefficient of inbreeding estimated from pedigrees and fitness traits (inbreeding‐fitness correlations) better reflects inbreeding depression than the relation between marker heterozygosity and fitness traits (heterozygosity‐fitness correlations). However, it has been suggested recently that heterozygosity‐fitness correlations should only be expected when inbreeding generates extensive identity disequilibrium (correlations in heterozygosity and homozygosity across loci throughout the genome). We tested this hypothesis in Mohor gazelle (Gazella dama mhorr) and Iberian lynx (Lynx pardinus). For Mohor gazelle, we calculated the inbreeding coefficient and measured heterozygosity at 17 microsatellite loci. For Iberian lynx, we measured heterozygosity at 36 microsatellite loci. In both species we estimated semen quality, a phenotypic trait directly related to fitness that is controlled by many loci and is affected by inbreeding depression. Both species showed evidence of extensive identity disequilibrium, and in both species heterozygosity was associated with semen quality. In the Iberian lynx the low proportion of normal sperm associated with low levels of heterozygosity was so extreme that it is likely to limit the fertility of males. In Mohor gazelle, although heterozygosity was associated with semen quality, inbreeding coefficient was not. This result suggests that when coefficient of inbreeding is calculated on the basis of a genealogy that begins after a long history of inbreeding, the coefficient of inbreeding fails to capture previous demographic information because it is a poor estimator of accumulated individual inbreeding. We conclude that among highly endangered species with extensive identity disequilibrium, examination of heterozygosity‐fitness correlations may be an effective way to detect inbreeding depression, whereas inbreeding‐fitness correlations may be poor indicators of inbreeding depression if the pedigree does not accurately reflect the history of inbreeding. Correlaciones Heterocigosidad‐ Adaptabilidad y Depresión Endogámica en Dos Especies de Mamíferos Críticamente en Peligro 相似文献
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Karen Pennesi Jadah Arokium Gordon McBean 《Mitigation and Adaptation Strategies for Global Change》2012,17(8):897-922
As the climate warms, stressors are developing that challenge the adaptive capabilities of Arctic peoples. In Nunavut, one of Canada??s Arctic territories, increased weather variability and changes in physical and climatic conditions are having profound effects on residents. One problem is that while these changes have magnified risks associated with travel and land-based activities, individuals lack sufficiently reliable and useful information on which to base decisions. In this paper, we argue that weather-related risk assessment can be improved by integrating local and scientific weather knowledge and making this information accessible to residents through the creation of weather hazards impact advisory groups. We present a qualitative case study of Iqaluit, the capital of Nunavut, using data from participant observation and semi-structured interviews conducted with indigenous and non-indigenous long-term residents in summer 2009. We examine how long-term residents of Iqaluit acquire, perceive, and use both local and scientific weather knowledge. We find that various barriers, such as a lack of land-based experience, cultural and linguistic differences, and an absence of social networks, prevent most people from obtaining all the information required to make fully informed decisions about the risks associated with land-based activities at different locations. Experienced hunters are perceived to be a reliable source of weather-related information, while scientific weather knowledge is not as accessible or informative as it could be. Increasing the potential use of traditional and scientific hazardous weather knowledge, by making both more universally accessible, can enhance strategies for adapting to climate change in the Arctic. 相似文献
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