全文获取类型
收费全文 | 1256篇 |
免费 | 27篇 |
国内免费 | 9篇 |
专业分类
安全科学 | 51篇 |
废物处理 | 47篇 |
环保管理 | 323篇 |
综合类 | 132篇 |
基础理论 | 381篇 |
污染及防治 | 192篇 |
评价与监测 | 106篇 |
社会与环境 | 45篇 |
灾害及防治 | 15篇 |
出版年
2023年 | 6篇 |
2022年 | 12篇 |
2021年 | 22篇 |
2020年 | 14篇 |
2019年 | 16篇 |
2018年 | 25篇 |
2017年 | 27篇 |
2016年 | 43篇 |
2015年 | 31篇 |
2014年 | 29篇 |
2013年 | 75篇 |
2012年 | 73篇 |
2011年 | 72篇 |
2010年 | 53篇 |
2009年 | 45篇 |
2008年 | 58篇 |
2007年 | 68篇 |
2006年 | 75篇 |
2005年 | 52篇 |
2004年 | 48篇 |
2003年 | 55篇 |
2002年 | 37篇 |
2001年 | 19篇 |
2000年 | 26篇 |
1999年 | 19篇 |
1998年 | 23篇 |
1997年 | 24篇 |
1996年 | 22篇 |
1995年 | 18篇 |
1994年 | 12篇 |
1993年 | 15篇 |
1992年 | 16篇 |
1991年 | 8篇 |
1990年 | 13篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 7篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 16篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 2篇 |
排序方式: 共有1292条查询结果,搜索用时 15 毫秒
531.
Moreno Di Marco Thomas Brooks Annabelle Cuttelod Lincoln D.C. Fishpool Carlo Rondinini Robert J. Smith Leon Bennun Stuart H.M. Butchart Simon Ferrier Ruud P.B. Foppen Lucas Joppa Diego Juffe‐Bignoli Andrew T. Knight John F. Lamoreux Penny F. Langhammer Ian May Hugh P. Possingham Piero Visconti James E.M. Watson Stephen Woodley 《Conservation biology》2016,30(2):392-402
World governments have committed to increase the global protected areas coverage by 2020, but the effectiveness of this commitment for protecting biodiversity depends on where new protected areas are located. Threshold‐ and complementarity‐based approaches have been independently used to identify important sites for biodiversity. We brought together these approaches by performing a complementarity‐based analysis of irreplaceability in important bird and biodiversity areas (IBAs), which are sites identified using a threshold‐based approach. We determined whether irreplaceability values are higher inside than outside IBAs and whether any observed difference depends on known characteristics of the IBAs. We focused on 3 regions with comprehensive IBA inventories and bird distribution atlases: Australia, southern Africa, and Europe. Irreplaceability values were significantly higher inside than outside IBAs, although differences were much smaller in Europe than elsewhere. Higher irreplaceability values in IBAs were associated with the presence and number of restricted‐range species; number of criteria under which the site was identified; and mean geographic range size of the species for which the site was identified (trigger species). In addition, IBAs were characterized by higher irreplaceability values when using proportional species representation targets, rather than fixed targets. There were broadly comparable results when measuring irreplaceability for trigger species and when considering all bird species, which indicates a good surrogacy effect of the former. Recently, the International Union for Conservation of Nature has convened a consultation to consolidate global standards for the identification of key biodiversity areas (KBAs), building from existing approaches such as IBAs. Our results informed this consultation, and in particular a proposed irreplaceability criterion that will allow the new KBA standard to draw on the strengths of both threshold‐ and complementarity‐based approaches. 相似文献
532.
Portrayal of sustainability principles in the mission statements and on home pages of the world's largest organizations
下载免费PDF全文
![点击此处可从《Conservation biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Stephen T. Garnett Michael J. Lawes Robyn James Kristen Bigland Kerstin K. Zander 《Conservation biology》2016,30(2):297-307
Conservation can be achieved only if sustainability is embraced as core to organizational cultures. To test the extent to which the related concepts of sustainability, conservation, response to climate change, poverty alleviation, and gender equity have been incorporated into organizational culture, we compared mission statements published from 1990 to 2000 with those published in 2014 for 150 organzations, including conservation nongovernmental organizations (NGOs), aid NGOs, government development agencies, resource extraction companies, and retailers (30 in each category). We also analyzed the 2014 home web pages of each organization. Relative to the earlier period, the frequency with which mission statements mentioned poverty alleviation, biodiversity conservation, and a range of sustainable practices increased only slightly by 2014, particularly among resource extractors and retail companies. Few organizations in any sector had embedded either climate change or gender equity into their mission statements. In addition, the proportional intensity with which any of the aspirations were expressed did not change between periods. For current home pages, conservation NGOs, resource extractors, and government agencies were significantly more likely to acknowledge the importance of matters that were not part of their core business, but few aid agencies or retail companies promoted goals beyond alleviation of crises and profit maximization, respectively. Overall, there has been some progress in recognizing poverty alleviation, biodiversity conservation, and sustainable practices, but gender equity and a determination to reduce impacts on climate change are still rarely promoted as central institutional concerns. Sustainability in general, and biodiversity conservation in particular, will not be achieved unless their importance is more widely apparent in core communication products of organizations. 相似文献
533.
An Object-Based Image Analysis of Pinyon and Juniper Woodlands Treated to Reduce Fuels 总被引:1,自引:0,他引:1
April Hulet Bruce A. Roundy Steven L. Petersen Ryan R. Jensen Stephen C. Bunting 《Environmental management》2014,53(3):660-671
Mechanical and prescribed fire treatments are commonly used to reduce fuel loads and maintain or restore sagebrush steppe rangelands across the Great Basin where pinyon (Pinus) and juniper (Juniperus) trees are encroaching and infilling. Geospatial technologies, particularly remote sensing, could potentially be used in these ecosystems to (1) evaluate the longevity of fuel reduction treatments, (2) provide data for planning and designing future fuel-reduction treatments, and (3) assess the spatial distribution of horizontal fuel structure following fuel-reduction treatments. High-spatial resolution color-infrared imagery (0.06-m pixels) was acquired for pinyon and juniper woodland plots where fuels were reduced by either prescribed fire, tree cutting, or mastication at five sites in Oregon, California, Nevada, and Utah. Imagery was taken with a Vexcel UltraCam X digital camera in June 2009. Within each treatment plot, ground cover was measured as part of the Sagebrush Steppe Treatment Evaluation Project. Trimble eCognition Developer was used to classify land cover classes using object-based image analysis (OBIA) techniques. Differences between cover estimates using OBIA and ground-measurements were not consistently higher or lower for any land cover class and when evaluated for individual sites, were within ±5 % of each other. The overall accuracy and the K hat statistic for classified thematic maps for each treatment were: prescribed burn 85 % and 0.81; cut and fell 82 % and 0.77, and mastication 84 % and 0.80. Although cover assessments from OBIA differed somewhat from ground measurements, they are sufficiently accurate to evaluate treatment success and for supporting a broad range of management concerns. 相似文献
534.
535.
536.
537.
Stephen D. Preston Richard B. Alexander David M. Wolock 《Journal of the American Water Resources Association》2011,47(5):887-890
Preston, Stephen D., Richard B. Alexander, and David M. Wolock, 2011. SPARROW Modeling to Understand Water‐Quality Conditions in Major Regions of the United States: A Featured Collection Introduction. Journal of the American Water Resources Association (JAWRA) 47(5):887‐890. DOI: 10.1111/j.1752‐1688.2011.00585.x 相似文献
538.
539.
540.
Cap and trade programs have considerable heterogeneity in permit validity and compliance timing. For example, permits have different validities across time (e.g., banking, borrowing, and seasons) and space (e.g., zonal restrictions), and compliance timing can be annual, in overlapping cycles, or in multi-year periods. We discuss nine prominent cap and trade programs along these dimensions and construct a general model of permit validity and compliance timing. We derive sufficient conditions under which abatement is invariant to compliance timing, i.e., compliance timing cannot smooth abatement cost shocks. Under these conditions, (i) expected compliance costs are invariant, (ii) the variance of compliance costs increases with the delayed compliance, (iii) equilibrium prices may not be unique, and (iv) the delayed compliance equilibrium may rely on “degenerate” prices not determined by marginal abatement costs. We demonstrate the model's broad applicability by illustrating different types of temporal permit validity. 相似文献