全文获取类型
收费全文 | 15540篇 |
免费 | 158篇 |
国内免费 | 126篇 |
专业分类
安全科学 | 374篇 |
废物处理 | 666篇 |
环保管理 | 1795篇 |
综合类 | 2542篇 |
基础理论 | 4309篇 |
环境理论 | 4篇 |
污染及防治 | 4023篇 |
评价与监测 | 1056篇 |
社会与环境 | 963篇 |
灾害及防治 | 92篇 |
出版年
2022年 | 125篇 |
2021年 | 104篇 |
2020年 | 100篇 |
2019年 | 106篇 |
2018年 | 196篇 |
2017年 | 234篇 |
2016年 | 326篇 |
2015年 | 266篇 |
2014年 | 453篇 |
2013年 | 1202篇 |
2012年 | 491篇 |
2011年 | 691篇 |
2010年 | 614篇 |
2009年 | 581篇 |
2008年 | 671篇 |
2007年 | 714篇 |
2006年 | 589篇 |
2005年 | 513篇 |
2004年 | 521篇 |
2003年 | 507篇 |
2002年 | 489篇 |
2001年 | 647篇 |
2000年 | 475篇 |
1999年 | 254篇 |
1998年 | 173篇 |
1997年 | 206篇 |
1996年 | 205篇 |
1995年 | 236篇 |
1994年 | 234篇 |
1993年 | 180篇 |
1992年 | 195篇 |
1991年 | 183篇 |
1990年 | 203篇 |
1989年 | 187篇 |
1988年 | 151篇 |
1987年 | 162篇 |
1986年 | 153篇 |
1985年 | 156篇 |
1984年 | 148篇 |
1983年 | 140篇 |
1982年 | 125篇 |
1981年 | 120篇 |
1980年 | 115篇 |
1979年 | 124篇 |
1978年 | 100篇 |
1977年 | 113篇 |
1975年 | 87篇 |
1974年 | 87篇 |
1973年 | 96篇 |
1972年 | 86篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
991.
Community-based coastal resource management has been widely applied within the Philippines. However, small-scale community-based reserves are often inefficient owing to management inadequacies arising because of a lack of local support or enforcement or poor design. Because there are many potential pitfalls during the establishment of even small community-based reserves, it is important for coastal managers, communities, and facilitating institutions to have access to a summary of the key factors for success. Reviewing relevant literature, we present a framework of lessons learned during the establishment of protected areas, mainly in the Philippines. The framework contains summary guidance on the importance of (1) an island location, (2) small community population size, (3) minimal effect of land-based development, (4) application of a bottom-up approach, (5) an external facilitating institution, (6) acquisition of title, (7) use of a scientific information database, (8) stakeholder involvement, (9) the establishment of legislation, (10) community empowerment, (11) alternative livelihood schemes, (12) surveillance, (13) tangible management results, (14) continued involvement of external groups after reserve establishment, and (15) small-scale project expansion.These framework components guided the establishment of a community-based protected area at Danjugan Island, Negros Occidental, Philippines. This case study showed that the framework was a useful guide that led to establishing and implementing a community-based marine reserve. Evaluation of the reserve using standard criteria developed for the Philippines shows that the Danjugan Island protected area can be considered successful and sustainable. At Danjugan Island, all of the lessons synthesized in the framework were important and should be considered elsewhere, even for relatively small projects. As shown in previous projects in the Philippines, local involvement and stewardship of the protected area appeared particularly important for its successful implementation. The involvement of external organizations also seemed to have a key role in the success of the Danjugan Island project by guiding local decision-makers in the sociobiological principles of establishing protected areas. However, the relative importance of each component of the framework will vary between coastal management initiatives both within the Philippines and across the wider Asian region.Published on line 相似文献
992.
Monitoring Forest Carbon Sequestration with Remote Sensing and Carbon Cycle Modeling 总被引:1,自引:0,他引:1
Sources and sinks of carbon associated with forests depend strongly on the management regime and spatial patterns in potential productivity. Satellite remote sensing can provide spatially explicit information on land cover, stand-age class, and harvesting. Carbon-cycle process models coupled to regional climate databases can provide information on potential rates of production and related rates of decomposition. The integration of remote sensing and modeling thus produces spatially explicit information on carbon storage and flux. This integrated approach was employed to compare carbon flux for the period 1992–1997 over two 165-km2 areas in western Oregon. The Coast Range study area was predominately private land managed for timber production, whereas the West Cascades study area was predominantly public land that was less productive but experienced little harvesting in the 1990s. In the Coast Range area, 17% of the land base was harvested between 1991 and 2000. Much of the area was in relatively young, productive-age classes that simulations indicate are a carbon sink. Mean annual harvest removals from the Coast Range were greater than mean annual net ecosystem production. On the West Cascades study area, a relatively small proportion (< 1%) of the land was harvested and the area as a whole was accumulating carbon. The spatially and temporally explicit nature of this approach permits identification of mechanisms underlying land base carbon flux.
Published online 相似文献
993.
K. Tybirk H. F. Alr?e P. Frederiksen 《Journal of Agricultural and Environmental Ethics》2004,17(3):221-222
Editorial Commentary
Editorial 相似文献994.
R. Goodland M. Ismail F. Strum David Walker Lupton Marc Jay Rogoff William Erich Cline David E. Goldenberg James C. Starbuck Lee S. Tesdell Anthony G. White John F. Schnell Richard S. Krannich Nan C. Burg Frederick Frankena Meredith Kirkpatrick U. G. Yermakov V. L. Mote C. ZumBrunnen T. B. Denisova V. L. Rauner P. P. Micklin G. L. Rutilevskiy 《Environmental management》1978,2(5):473-476
995.
996.
997.
998.
999.
1000.
Seventy-five samples of the crustacean fauna associated with the coral Madracis mirabilis (Duchassaing and Michelotti) were obtained at five sites along the west coast of Barbados in 1985. Samples were analyzed to determine whether any community response to eutrophication was evident. Ordination (multidimensional scaling) and classification (group average clustering) based on Bray-Curtis dissimilarity measures separated the fauna of highly eutrophied sites from those that were less eutrophied. Dominance plots based on relative abundance and log-normal plotting methods were ineffective in distinguishing the fauna of eutrophied sites. The crustacean fauna responded to eutrophication mainly by reduction of density of animals. No differences in species richness, number of site endemic species or rare species were observed between highly eutrophied and less eutrophied sites. Nine indicator species of eutrophy were identified on the basis of strong density differences between sites. 相似文献