全文获取类型
收费全文 | 1421篇 |
免费 | 100篇 |
国内免费 | 85篇 |
专业分类
安全科学 | 61篇 |
废物处理 | 6篇 |
环保管理 | 388篇 |
综合类 | 480篇 |
基础理论 | 360篇 |
污染及防治 | 57篇 |
评价与监测 | 50篇 |
社会与环境 | 151篇 |
灾害及防治 | 53篇 |
出版年
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 16篇 |
2021年 | 32篇 |
2020年 | 38篇 |
2019年 | 26篇 |
2018年 | 21篇 |
2017年 | 32篇 |
2016年 | 31篇 |
2015年 | 36篇 |
2014年 | 40篇 |
2013年 | 64篇 |
2012年 | 52篇 |
2011年 | 82篇 |
2010年 | 91篇 |
2009年 | 99篇 |
2008年 | 91篇 |
2007年 | 99篇 |
2006年 | 104篇 |
2005年 | 93篇 |
2004年 | 69篇 |
2003年 | 72篇 |
2002年 | 65篇 |
2001年 | 63篇 |
2000年 | 60篇 |
1999年 | 27篇 |
1998年 | 24篇 |
1997年 | 28篇 |
1996年 | 12篇 |
1995年 | 26篇 |
1994年 | 12篇 |
1993年 | 19篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 11篇 |
1989年 | 3篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1606条查询结果,搜索用时 265 毫秒
741.
广东省天然气一期总长约466.5km,其中干线长度约369.1km,支干线长约97.4km。项目建设区域包括广州、佛山、肇庆、惠州、韶关、清远和东莞6市。天然气管道建设因其工程特性、施工方式,不可避免对土地利用类型、土壤、植被、动物、农业等方面带来影响,其表征为景观生态的直接影响,由此带来生态系统结构和功能的改变。以广东省天然气一期为例,采用遥感解译和GIS分析技术进行生态影响评价。通过地貌、植被、土地利用现状和现代地理过程等要素的组合,结合景观破碎度、多样性、优势度等指标,定量评价管道建设造成的景观生态影响。选取植被、土壤亮度、湿度、热度等指数,确立各指数权重分后,建立生态评价模型,对生态系统质量进行综合评价,分析管道建设可能造成的生态系统影响。评价区内景观生态类型可分为水域、旱地、水田、林地、草地、建设用地6种,各占6.5%、9.9%、51.2%、25.2%、2.8%和4.3%,破碎度为0.298,均匀度0.743,优势度0.594;生态环境质量可分为良好、中等、较差3类,各占39.8%、26.0%和34.2%。 相似文献
742.
介绍了开展矿山生态环境监察的内涵、特点,分析了矿山资源开发引起的环境问题,总结了河北省环境监察发展历程、矿山生态环境监察内容及取得的成果,存在的问题,提出了对策。 相似文献
743.
Surface disposal of human waste by the smear method, a suggested but heretofore unexamined technique, was tested in three environments and examined for reductions in fecal mass and fecal indicator bacteria. Substantial reduction in fecal mass was observed after six and fourteen weeks of exposure in all environments, but extensive reduction in fecal indicator bacteria was observed in only the arid and alpine environments. Although surface smears appear favorable to cathole techniques in terms of indicator bacteria reduction, the application of this method is limited by several other factors common to backcountry sanitation situations. It is therefore likely that surface disposal would only be applicable in very remote, low use, alpine and arid settings where lack of soil development precludes the use of catholes and carry-out techniques are otherwise impractical. 相似文献
744.
745.
This study measures the impact of fanya juu terraces on the net value of crop income in a high‐rainfall area in the Ethiopian highlands using cross‐sectional multiple plot observations. Using propensity score matching methods we find that the net value of crop income for plots with fanya juu terraces is lower than for plots without fanya juu terraces. This finding makes it difficult to avoid concluding that while the technologies might reduce soil erosion and associated off‐site effects, they do so at the expense of poor farmers in the Ethiopian highlands. Therefore, fanya juu terraces cannot be characterized as a “win‐win” measure to reduce soil erosion. New agricultural technologies need to be profitable to the farmer if they are to be adopted and sustained. 相似文献
746.
Jssica Luiza S. Silva Marcela Tomaz Pontes de Oliveira Oswaldo Cruz-Neto Marcelo Tabarelli Ariadna Valentina Lopes 《Ambio》2021,50(4):884
Urbanization has rapidly increased in recent decades and the negative effects on biodiversity have been widely reported. Urban green areas can contribute to improving human well-being, maintaining biodiversity, and ecosystem services (e.g. pollination). Here we examine the evolution of studies on plant–pollinator interactions in urban ecosystems worldwide, reviewing also research funding and policy actions. We documented a significant increase in the scientific production on the theme in recent years, especially in the temperate region; tropical urban ecosystems are still neglected. Plant–pollinator interactions are threatened by urbanization in complex ways, depending on the studied group (plant or pollinator [generalist or specialist]) and landscape characteristics. Several research opportunities emerge from our review. Research funding and policy actions to pollination/pollinator in urban ecosystems are still scarce and concentrated in developed countries/temperate regions. To make urban green spaces contribute to the maintenance of biodiversity and the provision of ecosystem services, transdisciplinary approaches (ecological–social–economic–cultural) are needed.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01410-z) contains supplementary material, which is available to authorized users. 相似文献
747.
748.
Marc C. Coles‐Ritchie David W. Roberts Jeffrey L. Kershner Richard C. Henderson 《Journal of the American Water Resources Association》2007,43(3):731-743
Abstract: A method was developed to characterize ecological integrity of riparian sites based on the abundance of hydric species. This wetland index can be calculated with species data, or with community type data as performed here. Classified riparian community types were used to describe vegetation at 14 livestock exclosures and adjacent grazed areas. Community type wetland index values were generated and used to calculate site wetland index values. It was hypothesized that removal of livestock would result in higher wetland index values because of release from herbivory and decreased physical disturbance of vegetation, streambanks, and soil. The wetland index for exclosures was about 12% higher than grazed sites; differences were statistically significant (p < 0.01) based on paired t‐tests. The increase in hydric vegetation after livestock exclusion may have contributed to the greater bank stability (p = 0.002) and smaller width‐to‐depth ratio (p = 0.005) in exclosures. Challenges were encountered in using community types to describe and compare site vegetation, which could be avoided with species data collection. The wetland index can be a tool to monitor sites over time, compare sites with similar environments, or compare sites for which environmental differences can be accounted. 相似文献
749.
TRAN THI MY DIEU 《Environment, Development and Sustainability》2006,8(2):229-249
The food processing sector in Vietnam plays a vital role in its economic development, but its rapid growth seems to go hand-in-hand with environmental deterioration. Several decades of applying the conventional end-of-pipe approach made clear that it only deals with treating the symptoms. It is necessary to combine technological (end-of-pipe) solutions to overcome urgent pollution problems with ways to prevent wastes from being generated or to reuse their valuable material. This article presents a methodology for analyzing the possibilities for waste prevention in food processing industry in Vietnam. 相似文献
750.
Simulation of Rabies Epizootic Process in Fox Populations at a Limited Carrying Capacity of Biotopes
To describe the epizootic process of rabies in fox populations, a model based on a cellular automata network (Toffoli and Margolus, 1991) was constructed. The cell state and the rules of transition from one state to another were determined in accordance with a modification of the previous model based on a differential equation system, which was proposed to describe the epizootics of fox rabies in Western Europe. The new model provides the possibility of simulating spatial heterogeneity and indices of animal mobility related, in particular, to the seasonal features of fox ecology. Calculations were made using population parameters characteristic of biotopes with a low carrying capacity (the steppe zone of Western Siberia). According to the model, the maintenance of rabies epizootics in these biotopes is possible on condition that the mobility of foxes in them is much higher than in the biotopes with a high carrying capacity. This model can be used for prognosis and epidemiological control in natural rabies foci. 相似文献