全文获取类型
收费全文 | 470篇 |
免费 | 26篇 |
国内免费 | 36篇 |
专业分类
安全科学 | 25篇 |
废物处理 | 2篇 |
环保管理 | 131篇 |
综合类 | 114篇 |
基础理论 | 149篇 |
环境理论 | 1篇 |
污染及防治 | 22篇 |
评价与监测 | 13篇 |
社会与环境 | 40篇 |
灾害及防治 | 35篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 16篇 |
2020年 | 14篇 |
2019年 | 14篇 |
2018年 | 12篇 |
2017年 | 18篇 |
2016年 | 31篇 |
2015年 | 22篇 |
2014年 | 11篇 |
2013年 | 22篇 |
2012年 | 11篇 |
2011年 | 36篇 |
2010年 | 22篇 |
2009年 | 35篇 |
2008年 | 27篇 |
2007年 | 46篇 |
2006年 | 24篇 |
2005年 | 23篇 |
2004年 | 23篇 |
2003年 | 19篇 |
2002年 | 9篇 |
2001年 | 12篇 |
2000年 | 19篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有532条查询结果,搜索用时 15 毫秒
371.
372.
台湾集集地震近断层强震地面运动加速度时程的随机特性 总被引:7,自引:1,他引:7
将强震地面运动加速度时程看作随机过程,选取台湾集集地震的30组近断层加速度时程为样本,研究其相关特性。3方向集系上的自相关矩阵和互相关矩阵表明3方向的加速度时程均为非平稳随机过程,并且相关系数的分布是随机的,这种随机相关性是无法用确定性的数学模型来模拟的。为此,又研究了样本函数的相关特性,即随机过程样本函数的相关函数,结果发现在随机过程的相关函数中包含有明显的随机函数分量,即相关函数仍为一随机过程,我们称这样的随机过程为超随机过程,本文建立了超随机过程相关函数的数学模型。本文的研究表明近断层强地面运动为一复杂的随机过程,对其相关特性的研究应当包括相关系数(性)的大小和相关系数(性)的随机分布两个方面。 相似文献
373.
374.
金华市高山与平原无公害蔬菜生产的环境质量比较 总被引:3,自引:0,他引:3
对金华市高山、低山和平原无公害蔬菜基地的水、大气和土壤等环境质量的系统监测及对蔬菜生产现状的调查分析结果表明:三地环境优良,均适宜发展无公害蔬菜生产、高山区气候独特,昼夜温差大,蔬菜产量高,品质好,是发展经济途径之一,但山地环境脆弱,应加强环境保护。 相似文献
375.
There is a long history of fire management in African savannas, but knowledge of historical and current use of fire is scarce in savanna-woodland biomes. This study explores past and present fire management practices and perceptions of the Khwe (former hunter-gatherers) and Mbukushu (agropastoralists) communities as well as government and non-government stakeholders in Bwabwata National Park in north-east Namibia. Semi-structured interviews and focus groups were used in combination with satellite data (from 2000 to 2015), to investigate historical and current fire management dynamics. Results show that political dynamics in the region disrupted traditional fire practices, specifically a policy of fire suppression was initiated by colonial governments in 1888 and maintained during independence until 2005. Both the Khwe and Mbukushu communities use early season (i.e. between April and July) fires for diverse interrelated historical and current livelihood activities, and park management for managing late season fires. The Mbukushu community also use late season burns to prepare land for crops. In this study, we use a pyrogeographic framework to understand the human dimension of fires. This study reveals how today’s fire management practices and policies, specifically the resurgence of early season burning are entrenched in the past. Understanding and acknowledging the social and cultural dynamics of fire, alongside participatory stakeholder engagement is critical for managing fires in the future.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01351-7) contains supplementary material, which is available to authorized users. 相似文献
376.
Abstract: We explored the role of conservation biology in the planning of a natural-heritage system that includes long, wide conservation corridors situated primarily on private lands, and established to connect natural core areas in the Oak Ridges Moraine of Ontario, Canada. We based our review on government documents, semi-structured interviews with participants involved in this land-use planning process, and our involvement with the issue from 1990 through 2002. Conservation biology had a major influence on the outcome of the land-use planning process for this moraine. The landform was identified as an area of value by the environmental movement within the context of a number of ongoing government studies that began in the late 1980s and early 1990s. Conservation biologists and planners in government, the environmental movement, and the private sector carried out work related to conservation biology, including inventories and the development and application of criteria for the delineation of core areas and conservation corridors. Once the political timing was favorable (2001–2002), decision makers linked the science of conservation biology to planning policies and law in Ontario. The Oak Ridges Moraine land-use planning process was precedent setting in Canada, and possibly internationally. To our knowledge this is the first time long, wide conservation corridors on private lands were regulated through land-use-planning legislation and led to restrictions on urban development and aggregate resource extraction. 相似文献
377.
TOBY A. GARDNER‡ MARCO ANTÔNIO RIBEIRO-JÚNIOR† JOS BARLOW† TERESA CRISTINA SAUER ÁVILA-PIRES† MARINUS S. HOOGMOED† CARLOS A. PERES 《Conservation biology》2007,21(3):775-787
Abstract: Plantation forests and second-growth forests are becoming dominant components of many tropical forest landscapes. Yet there is little information available concerning the consequences of different forestry options for biodiversity conservation in the tropics. We sampled the leaf-litter herpetofauna of primary, secondary, and Eucalyptus plantation forests in the Jari River area of northeastern Brazilian Amazonia. We used four complementary sampling techniques, combined samples from 2 consecutive years, and collected 1739 leaf-litter amphibians (23 species) and 1937 lizards (30 species). We analyzed the data for differences among forest types regarding patterns of alpha and beta diversity, species-abundance distributions, and community structure. Primary rainforest harbored significantly more species, but supported a similar abundance of amphibians and lizards compared with adjacent areas of second-growth forest or plantations. Plantation forests were dominated by wide-ranging habitat generalists. Secondary forest faunas contained a number of species characteristic of primary forest habitat. Amphibian communities in secondary forests and Eucalyptus plantations formed a nested subset of primary forest species, whereas the species composition of the lizard community in plantations was distinct, and was dominated by open-area species. Although plantation forests are relatively impoverished, naturally regenerating forests can help mitigate some negative effects of deforestation for herpetofauna. Nevertheless, secondary forest does not provide a substitute for primary forest, and in the absence of further evidence from older successional stands, we caution against the optimistic claim that natural forest regeneration in abandoned lands will provide refuge for the many species that are currently threatened by deforestation . 相似文献
378.
379.
济南市土地利用现状与可持续发展研究 总被引:3,自引:0,他引:3
以济南市为研究对象,根据近几年来的土地详查数据,对各种地类的情况做出统计,总结出该区的土地利用情况,并分析了其现状特点,指出当前土地利用中存在的主要问题,提出相应的研究对策。 相似文献
380.