全文获取类型
收费全文 | 710篇 |
免费 | 35篇 |
国内免费 | 55篇 |
专业分类
安全科学 | 15篇 |
废物处理 | 4篇 |
环保管理 | 242篇 |
综合类 | 238篇 |
基础理论 | 147篇 |
污染及防治 | 45篇 |
评价与监测 | 40篇 |
社会与环境 | 56篇 |
灾害及防治 | 13篇 |
出版年
2024年 | 3篇 |
2023年 | 7篇 |
2022年 | 15篇 |
2021年 | 17篇 |
2020年 | 14篇 |
2019年 | 18篇 |
2018年 | 19篇 |
2017年 | 23篇 |
2016年 | 28篇 |
2015年 | 33篇 |
2014年 | 29篇 |
2013年 | 33篇 |
2012年 | 28篇 |
2011年 | 57篇 |
2010年 | 36篇 |
2009年 | 58篇 |
2008年 | 52篇 |
2007年 | 54篇 |
2006年 | 44篇 |
2005年 | 34篇 |
2004年 | 26篇 |
2003年 | 22篇 |
2002年 | 23篇 |
2001年 | 24篇 |
2000年 | 12篇 |
1999年 | 21篇 |
1998年 | 3篇 |
1997年 | 10篇 |
1996年 | 3篇 |
1995年 | 8篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 7篇 |
1988年 | 3篇 |
1986年 | 4篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 2篇 |
排序方式: 共有800条查询结果,搜索用时 15 毫秒
541.
Supplementing Land-Use Statistics with Landscape Metrics: Some Methodological Considerations 总被引:6,自引:0,他引:6
Landscape monitoring usually relies on land-use statistics whichreflect the share of land-sue/land cover types. In order tounderstand the functioning of landscapes, landscape pattern mustbe considered as well. Indicators which address the spatialconfiguration of landscapes are therefore needed. Thesuitability of landscape metrics, which are computed from thetype, geometry and arrangement of patches, is examined. Two casestudies in a surface mining region show that landscape metricscapture landscape structure but are highly dependent on the datamodel and on the methods of data analysis. For landscape metricsto become part of policy-relevant sets of environmentalindicators, standardised procedures for their computation fromremote sensing images must be developed. 相似文献
542.
土地利用/覆被变化(LUCC)环境效应研究综述 总被引:9,自引:0,他引:9
土地利用/覆被变化能直接反映当今全球环境变化的主导因子--人类活动,为此土地利用/覆被变化产生的环境问题已引起人类社会的广泛关注,深入研究这些问题具有重要的理论意义和实践价值.针对土地利用/覆被变化引起的环境效应的复杂性、累积性,本文在总结国内外LUCC环境效应的研究成果的同时,把LUCC环境效应分为:土壤环境效应、大气环境效应、水环境效应以及生态效应四类进行阐述,并结合目前研究在内容和方法方面存在缺乏统一的指标体系、研究区域时空尺度单一、以单要素静态研究为主、实验研究相对薄弱以及动态模拟不够等问题对其发展趋势进行了探讨. 相似文献
543.
川中丘陵区荒坡利用方式对水土流失影响的研究 总被引:3,自引:0,他引:3
川中丘陵区荒坡面积占据一定比重,防治水土流失,合理利用荒坡水土资源,对发展本区经济起着重要作用。本文通过网点观测来探求合理利用方式,为荒坡开发利用提供决策依据。 相似文献
544.
A. Heil B. Langmann E. Aldrian 《Mitigation and Adaptation Strategies for Global Change》2007,12(1):113-133
Numerical modelling of fire-related smoke haze episodes in Southeast Asia is important for both prediction and assessment of atmospheric impacts, especially when observational data are fragmentary, as is the case in Indonesia. This work describes the atmospheric fate of smoke particles emitted during the 1997 Indonesian fires modelled with a regional atmospheric chemistry model. We established a new fire emission inventory and calculate that 55 teragram (Tg) of particulate matter and 1098 Tg of carbon were released during this fire episode. Our emission estimate is an intermediate value compared with other studies. Utilising different scenarios, we demonstrate the variable atmospheric impacts of surface vegetation fires and peat soil fires separately and also investigate the sensitivity of smoke dispersion to the differing meteorological conditions of an El Niño and a normal year. When peat fires are included in the emission inventory, modelled ambient particle concentrations exceed the ambient air quality standard across transboundary scales. In a scenario including only surface vegetation fires, ambient air quality standards are exceeded only in areas close to the main fires. This scenario demonstrates the prominent role of fires in peat areas in causing regional air pollution episodes. In years with normal meteorological conditions, intermittent precipitation and associated wet deposition during the dry season are predicted to remove most of the particulate emissions close to the sources. Strongly reduced rainfall and generally stronger southeasterly winds during El Niño years provide favourable conditions for larger scale smoke haze pollution. 相似文献
545.
晋西南黄土高原区植被覆盖度变化及其生态效应评估 总被引:2,自引:0,他引:2
水土流失和生态退化是黄土高原区面临的严峻问题,已经严重制约了经济发展。基于TM和OLI数据,分别估算晋西南黄土高原区的植被覆盖度(FVC)和遥感生态指数(RSEI),定量分析了晋西南黄土高原区的植被和生态恢复效果,并提出需要重点治理的区域。研究结果表明:(1)15年间晋西南黄土高原区的植被覆盖度和遥感生态指数都呈现增加的趋势,FVC指数从2002年的42.69%增加至2017年的47.67%,RSEI指数由2002年的45%增加至2017年的52.5%,反映出研究区生态质量有了明显提高;(2)除研究区内芝河流域、汾河谷地和沁河流域的生态质量出现严重退化外,研究区大部分区域的FVC指数和RSEI指数都呈改善趋势,因此需对芝河流域、汾河谷地和沁河流域加大生态治理力度;(3)除研究区汾河谷地外,其余地区植被覆盖度和遥感生态指数的变化趋势基本吻合,汾河谷地由于冬小麦大面积种植,植被覆盖度得到一定程度改善,但遥感生态指数并没有明显改善。 相似文献
546.
铅电解阳极板制作之前 ,需对粗铅或残极进行熔化 ,在这个过程中会产生很多铅烟尘 ,如不对铅烟尘进行回收 ,就会污染周围的空气。有必要采用收尘装置 ,解决这一污染问题 相似文献
547.
548.
549.
--Hainan
Island, located at the southern end of China, hasless than 0.4% of land area but contains
13% of plant and animalspecies in China. During the last four decades many primary
forestshave been converted to shrub land, grassland, and tree planation(e.g., eucalyptus
forest). As a result, area of primary tropicalforest has been reduced from 25.8% in the
1950s to 4% in the 1990s.To assess impacts of land conversion on plant and bird
speciesdiversity, a series of samples in primary forest and four types ofconverted lands
were took. The land conversion had tremendouslyreduced both plant and bird species
diversity. Specifically, plantspecies richness per site was 83.7 in primary forest, 28.3
in shrubland, 12.5 in grassland, 14.4 in eucalyptus forest, and 21.4 inAcacia forest. Bird
species richness showed a similar trend 22.0in primary forest, 14.5 in shrub land, 2.5 in
grassland, 4.9 ineucalyptus forest, and 9.0 in Acacia forest. The Shannon speciesdiversity
indices for plants in the five types of land cover were3.69, 1.99, 0.97, 1.47 and 2.07,
respectively. Similarly, the Shannon indices for bird species diversity were the highest
in primary forest, and lowest in grassland, and intermediate in shrubland and eucalyptus
forest. 相似文献
550.