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排序方式: 共有321条查询结果,搜索用时 171 毫秒
171.
Government administered protected areas (PAs) have dominated conservation strategies, discourse, and research, yet private actors are increasingly managing land for conservation. Little is known about the social and environmental outcomes of these privately protected areas (PPAs). We searched the global literature in English on PPAs and their environmental and social outcomes and identified 412 articles suitable for inclusion. Research on PPAs was geographically skewed; more studies occurred in the United States. Environmental outcomes of PPAs were mostly positive (89%), but social outcomes of PPAs were reported less (12% of all studies), and these outcomes were more mixed (65% positive). Private protected areas increased the number or extent of ecosystems, ecoregions, or species covered by PAs (representativeness) and PA network connectivity and effectively reduced deforestation and restored degraded lands. Few PPA owners reported negative social outcomes, experienced improved social capital, increased property value, or a reduction in taxes. Local communities benefited from increased employment, training, and community-wide development (e.g., building of schools), but they reported reduced social capital and no significant difference to household income. The causal mechanisms through which PPAs influence social and environmental outcomes remain unclear, as does how political, economic, and social contexts shape these mechanisms. Future research should widen the geographical scope and diversify the types of PPAs studied and focus on determining the casual mechanisms through which PPA outcomes occur in different contexts. We propose an assessment framework that could be adopted to facilitate this process. 相似文献
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Barbara A. Doll Dani E. Wise‐Frederick Carolyn M. Buckner Shawn D. Wilkerson William A. Harman Rachel E. Smith Jean Spooner 《Journal of the American Water Resources Association》2002,38(3):641-651
ABSTRACT: Hydraulic geometry relationships, or regional curves, relate bankfull stream channel dimensions to watershed drainage area. Hydraulic geometry relationships for streams throughout North Carolina vary with hydrology, soils, and extent of development within a watershed. An urban curve that is the focus of this study shows the bankfull features of streams in urban and suburban watersheds throughout the North Carolina Piedmont. Seventeen streams were surveyed in watersheds that had greater than 10 percent impervious cover. The watersheds had been developed long enough for the streams to redevelop bankfull features, and they had no major impoundments. The drainage areas for the streams ranged from 0.4 to 110.3 square kilometers. Cross‐sectional and longitudinal surveys were conducted to determine the channel dimension, pattern, and profile of each stream and power functions were fitted to the data. Comparisons were made with regional curves developed previously for the rural Piedmont, and enlargement ratios were produced. These enlargement ratios indicated a substantial increase in the hydraulic geometry for the urban streams in comparison to the rural streams. A comparison of flood frequency indicates a slight decrease in the bankfull discharge return interval for the gaged urban streams as compared to the gaged rural streams. The study data were collected by North Carolina State University (NCSU), the University of North Carolina at Charlotte (UNC), and Charlotte Storm Water Services. Urban regional curves are useful tools for applying natural channel design in developed watersheds. They do not, however, replace the need for field calibration and verification of bankfull stream channel dimensions. 相似文献
176.
Understanding the role of negative affectivity (NA) in relations between job stressors and resultant strains has been a major source of research interest in the organizational literature for almost two decades. In this study, we propose a contingency approach, whereby the role of NA depends on the nature of the strain construct under investigation. Specifically, we predicted that perceived job stressors would fully mediate the relationship between NA and turnover intentions, while job stressors would only partially mediate the relationship between NA and job and life satisfaction, and job stressors would be unrelated to depression once NA was taken into account. The relative fit of these four models is tested utilizing data from two divergent samples (sales representatives and managers) employing both self‐ and informant reports of strain measures where feasible. Hypotheses regarding the specified nature of the NA → stressor → strain relationship generally were supported and replicated across samples. In addition, an alternate model specifying that NA moderates the relationship between stressors and strains was not supported for any strain variable. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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B. J. Wiley D. H. Ball S. M. Arcidiacono S. Sousa J. M. Mayer D. L. Kaplan 《Journal of Polymers and the Environment》1993,1(1):3-9
The influence of carbon, nitrogen, and phosphate source, along with concentration, was determined for effect on the weight average molecular weight, molecular weight distribution, and yield of pullulan produced byAureobasidium pullulans NRRL-Y 6220. Batch systems, scale-up batch, and continuous fermentations of 1 L and 10 L were also evaluated as were processing variables, including solvents, and extraction conditions. Products with weight average molecular weight from 1.0 × 105 to 4.0 × 106 were produced in 100-g quantities by varying fermentation conditions such as constituents of the culture medium, pH, and length of incubation. Three sets of culture conditions were defined for the formation of low (<5.0×105), medium (1.0–2.0×106), and high (>2.0×106) weight average molecular weight polymer. These defined molecular weight fractions of pullulan were used in further studies in producing films and fibers. 相似文献
178.
Overwhelming evidence demonstrates the benefits of positive affect for various life and work outcomes. However, the relevant organizational research almost exclusively has focused on general positive affect, thereby implying that all positive affect has consistent and equal relationships with other work variables. The purposes of this theoretical paper are to review and highlight research from basic psychology demonstrating the unique nature and correlates of specific positive emotions and to translate those ideas and findings into the organizational context. Specifically, we discuss three discrete positive emotions—pride, interest, and gratitude—and offer propositions regarding their differential effects on relevant workplace outcomes and regarding the differential antecedents of them. Our hope is that this paper stimulates future research on this topic, and we offer specific research strategies and ideas to facilitate those endeavors. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Nicholas D. Higgs Adam J. Reed Rachel Hooke David J. Honey Olaf Heilmayer Sven Thatje 《Marine Biology》2009,156(5):1073-1081
We present information on the reproductive biology, population structure, and growth of the brooding Antarctic bivalve Adacnarca nitens Pelseneer 1903, from the Ross Sea, Antarctica. Individuals ranging from 0.85 to 6.00 mm were found attached to a hydrozoan colony. This
species shows low fecundity and large egg size, common to other brooding species. The minimum size at which oogenesis was
detected was 2.3 mm and the minimum size at which brooding was evident was 3.9 mm. Embryos of a full range of developmental
stages were brooded simultaneously in females. The population showed a log–normal distribution and results suggest non-periodic
reproduction with continuous embryonic development. The reproductive traits of A. nitens are discussed in the context of circum-Antarctic species distribution and limitations to dispersal in brooding benthic invertebrates. 相似文献