全文获取类型
收费全文 | 5592篇 |
免费 | 402篇 |
国内免费 | 1762篇 |
专业分类
安全科学 | 492篇 |
废物处理 | 263篇 |
环保管理 | 461篇 |
综合类 | 3316篇 |
基础理论 | 952篇 |
环境理论 | 1篇 |
污染及防治 | 1481篇 |
评价与监测 | 335篇 |
社会与环境 | 257篇 |
灾害及防治 | 198篇 |
出版年
2024年 | 31篇 |
2023年 | 91篇 |
2022年 | 300篇 |
2021年 | 289篇 |
2020年 | 289篇 |
2019年 | 202篇 |
2018年 | 230篇 |
2017年 | 280篇 |
2016年 | 281篇 |
2015年 | 314篇 |
2014年 | 425篇 |
2013年 | 561篇 |
2012年 | 526篇 |
2011年 | 561篇 |
2010年 | 424篇 |
2009年 | 407篇 |
2008年 | 384篇 |
2007年 | 370篇 |
2006年 | 308篇 |
2005年 | 222篇 |
2004年 | 170篇 |
2003年 | 175篇 |
2002年 | 154篇 |
2001年 | 132篇 |
2000年 | 119篇 |
1999年 | 88篇 |
1998年 | 74篇 |
1997年 | 75篇 |
1996年 | 50篇 |
1995年 | 42篇 |
1994年 | 43篇 |
1993年 | 28篇 |
1992年 | 34篇 |
1991年 | 12篇 |
1990年 | 23篇 |
1989年 | 16篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1958年 | 2篇 |
排序方式: 共有7756条查询结果,搜索用时 46 毫秒
961.
Cu,Cr and As distribution in soils adjacent to pressure-treated decks,fences and poles 总被引:1,自引:0,他引:1
Chirenje T Ma LQ Clark C Reeves M 《Environmental pollution (Barking, Essex : 1987)》2003,124(3):407-417
Chromated copper arsenate (CCA)-treated wood has been widely used in the Southeastern United States to protect wood products from microbial and fungal decay. The aims of this study were to (1). determine the distribution of arsenic (As), chromium (Cr), and copper (Cu), in soils surrounding CCA-treated wood structures such as decks, fences and poles; and (2). evaluate the impacts of these structures on As, Cr and Cu loading of the soils. Profile and lateral soil samples were collected under CCA-treated decks and adjacent to poles and fences. The results showed elevation of As, Cr and Cu concentrations close to and under the structures, with mean As concentrations as high as 23 mg x kg(-1) close to utility poles compared with less than 3 mg x kg (-1) at distances of about 1.5 m away. Concentrations of As, Cr, and Cu decreased with depth in areas close to CCA-treated poles. However, these results were only apparent in relatively new structures. A combination of weathering and leaching with time may have reduced the impact in older poles. Increased concentrations of As, Cu and Cr were also observed close to CCA-treated decks and fences, with age showing a similar impact. These results are helpful for CCA-treated wood product users to determine the safe use of these structures. 相似文献
962.
Studies on applying the photochemical UV/TiO2 oxidation process to treat the lignin-containing wastewater for dissolved organic carbon (DOC), color and reducing A254 (the absorption at the wavelength of 254 nm) have been carried out. The data obtained in this study demonstrate that the UV/TiO2 process is effective in oxidizing the lignin thus reducing the color and DOC of the wastewater treated. The combined UV/TiO2 treatment can achieve better removal of DOC and color than the UV treatment alone. Color removal, based on American Dye Manufacture Index (ADMI) measurement, is greater than 99% if the pH is maintained at 3.0 with the addition of 1 g l(-1) TiO2. When 10 g l(-1) TiO2 is applied, the oxidation reduction potential (ORP) value is reached to result in an 88% removal of both DOC and color. A model was developed based on the variation of ORP during the photochemical reaction to simulate the decoloring process. The proposed model can be used to predict the color removal efficiency of the UV/TiO2 process. 相似文献
963.
The influence of pH on the degradation of phenol and chlorophenols by potassium ferrate 总被引:16,自引:0,他引:16
This paper presents information concerning the influence of solution pH on the aqueous reaction between potassium ferrate and phenol and three chlorinated phenols: 4-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP). The redox potential and aqueous stability of the ferrate ion, and the reactivity of dissociating compounds, are known to be pH dependent. Laboratory tests have been undertaken over a wide range of pH (5.8-11) and reactant concentrations (ferrate:compound molar ratios of 1:1 to 8:1). The reactivity of trichloroethylene was also investigated as a reference compound owing to its non-dissociating nature. The extent of compound degradation by ferrate was found to be highly pH dependent, and the optimal pH (maximum degradation) decreased in the order: phenol/CP, DCP, TCP; at the optimal pH the degree of degradation of these compounds was similar. The results indicate that for the group of phenol and chlorophenols studied, the presence of an increasing number of chlorine substituent atoms corresponds to an increasing reactivity of the undissociated compound, and a decreasing reactivity of the dissociated compound. 相似文献
964.
Reactions of lead sorption onto soil are largely affected by properties and composition of soil and its solution. In this study, the lead sorption onto regosol eutric soil from Francisco I. Madero, Zacatecas, Mexico is evaluated at different pH values. Soil samples were suspended in lead solutions of 10, 25, 50, 100, 150, 200, 300, and 400 mg/l (as Pb(NO3)2). The pH was adjusted at 2, 3, 4, and 5.5 with nitric acid for each of the lead solution concentrations. In all the cases the ionic strength was I=0.09 M with calcium nitrate. The solid-liquid-ratios were fixed in 1:100 and 1:200 g/ml. The results show that lead sorption increases when pH increases. Experimental isotherms were adjusted by both Langmuir and Freundlich models. The Langmuir affinity parameter, K, indicates that the lead sorption capacity of Francisco I. Madero soils is largely perceptible to pH changes. 相似文献
965.
将计算机实时监测和控制技术引入到城市垃圾焚烧设备中,对回转炉床式焚烧炉的整个流程中各环节的生产数据,进行实时监测及控制,以提高焚烧炉的焚烧量和焚烧质量,使焚烧效率最佳,并且保证系统的安全可靠运行。 相似文献
966.
967.
968.
969.
970.
环境中手性污染物对映体选择性行为的研究历史不长 ,但由于手性化合物对映体生物活性的差异性 ,手性污染物在环境中的对映体选择性行为已愈来愈引起人们的关注。本文对近 10多年来手性污染物的环境行为研究进行全面评述 相似文献