全文获取类型
收费全文 | 4916篇 |
免费 | 451篇 |
国内免费 | 1491篇 |
专业分类
安全科学 | 523篇 |
废物处理 | 201篇 |
环保管理 | 358篇 |
综合类 | 3137篇 |
基础理论 | 754篇 |
环境理论 | 2篇 |
污染及防治 | 988篇 |
评价与监测 | 316篇 |
社会与环境 | 289篇 |
灾害及防治 | 290篇 |
出版年
2024年 | 22篇 |
2023年 | 96篇 |
2022年 | 287篇 |
2021年 | 242篇 |
2020年 | 242篇 |
2019年 | 192篇 |
2018年 | 211篇 |
2017年 | 205篇 |
2016年 | 226篇 |
2015年 | 267篇 |
2014年 | 351篇 |
2013年 | 464篇 |
2012年 | 467篇 |
2011年 | 457篇 |
2010年 | 369篇 |
2009年 | 337篇 |
2008年 | 325篇 |
2007年 | 327篇 |
2006年 | 333篇 |
2005年 | 217篇 |
2004年 | 150篇 |
2003年 | 141篇 |
2002年 | 165篇 |
2001年 | 138篇 |
2000年 | 143篇 |
1999年 | 87篇 |
1998年 | 63篇 |
1997年 | 76篇 |
1996年 | 65篇 |
1995年 | 51篇 |
1994年 | 38篇 |
1993年 | 23篇 |
1992年 | 27篇 |
1991年 | 17篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有6858条查询结果,搜索用时 421 毫秒
441.
442.
Biodiversity maintenance and soil improvement are key sustainable forestry objectives. Research on the effects of bamboo forest
management on plant diversity and soil properties are therefore necessary in bamboo-growing regions, such as southeastern
China’s Shunchang County, that have not been studied from this perspective. We analyzed the effects of different Phyllostachys pubescens proportions in managed forests on vegetation structure and soil properties using pure Cunninghamia lanceolata forests as a contrast, and analyzed the relation between understory plants and environmental variables (i.e., topography,
stand and soil characteristics) by canonical correspondence analysis (CCA). The forest with 80% P. pubescens and 20% hardwoods (such as Phoebe bournei, Jatropha curcas, Schima superba) maintained the highest plant diversity and best soil properties, with significantly higher plant diversity than the C. lanceolata forest, and better soil physicochemical and biological properties. The distribution of understory plants is highly related
to environmental factors. Silvicultural disturbance strongly influenced the ability of different bamboo forests to maintain
biodiversity and soil quality under extensive management, and the forest responses to management were consistent with the
intermediate-disturbance hypothesis (i.e., diversity and soil properties were best at intermediate disturbance levels). Our
results suggest that biodiversity maintenance and soil improvement are important management goals for sustainable bamboo management.
To achieve those objectives, managers should balance the inputs and outputs of nutrients and protect understory plants by
using appropriate fertilizer (e.g., organic fertilizer), adjusting stand structure, modifying utilization model and the harvest
time, and controlling the intensity of culms and shoots harvests. 相似文献
443.
444.
445.
446.
447.
Guan-yong Su Zi-shen Gao Yijun Yu Jia-chun Ge Si Wei Jian-fang Feng Feng-yan Liu John P. Giesy Hong-xia Yu 《Environmental science and pollution research international》2010,17(3):634-642
Background, aim, and scope
Polybrominated diphenyl ethers (PBDEs) and their metabolites are toxic to animals, and concentrations of the PBDEs metabolites can exceed those of the parent materials. But no information was available on concentrations of PBDEs metabolites in the lower Yangtze River in the region around Jiangsu Province of China, which is heavily urbanized and industrialized area. The aims of this study were to determine whether PBDEs and their methoxylated PBDEs (MeO-PBDEs) were accumulated in Coilia sp. in this area and to investigate the potential sources for these two kinds of brominated organic pollutants. 相似文献448.
Juan Huang Yanli Feng Jiamo Fu Guoying Sheng 《Environmental science and pollution research international》2010,17(5):1129-1136
Background, aim, and scope
Carbonyl compounds have been paid more and more attention because some carbonyl species have been proven to be carcinogenic or a risk for human health. Plant leaves are both an important emission source and an important sink of carbonyl compounds. But the research on carbonyl compounds from plant leaves is very scarce. In order to make an approach to the emission mechanism of plant leaves, a new method was established to extract carbonyl compounds from fresh plant leaves. 相似文献449.
Atmospheric deposition of phthalate esters in a subtropical city 总被引:1,自引:0,他引:1
Feng Zeng Yujun Lin Kunyan Cui Jiaxin Wen Yongqin Ma Hongli Chen Fang Zhu Zhiling Ma Zunxiang Zeng 《Atmospheric environment (Oxford, England : 1994)》2010,44(6):834-840
In Chinese cities, air pollution has become a serious and aggravating environmental problem undermining the sustainability of urban ecosystems and the quality of urban life. Bulk atmospheric deposition samples were collected two-weekly, from February 2007 to January 2008, at three representative areas, one suburban and two urbanized, in the subtropical city, Guangzhou, China, to assess the deposition fluxes and seasonal variations of phthalate esters (PAEs). Sixteen PAE congeners in bulk deposition samples were measured and the depositional fluxes of ∑16PAEs ranged from 3.41 to 190 μg m?2 day?1, and were highly affected by local anthropogenic activities. The significant relationship between PAEs and particulate depositional fluxes (correlation coefficient R2 = 0.72, P < 0.001) showed PAEs are associated primarily with particles. Temporal flux variations of PAEs were influenced by seasonal changes in meteorological parameters, and the deposition fluxes of PAEs were obviously higher in wet season than in dry season. Diisobutyl phthalate (DiBP), Di-n-butyl phthalate (DnBP), and Di(2-ethylhexyl) phthalate (DEHP) dominated the PAE pattern in bulk depositions, which is consistent with a high consumption of the plasticizer market in China. PAE profiles in bulk deposition showed similarities exhibited in both time and space, and a weak increase of high molecular weight PAE (HMW PAE) contribution in the wet season compared to those in the dry season. Average atmospheric deposition fluxes of PAEs in the present study were significantly higher than those from other studies, reflecting strong anthropogenic inputs as a consequence of rapid industrial and urban development in the region. 相似文献
450.