全文获取类型
收费全文 | 355篇 |
免费 | 41篇 |
国内免费 | 280篇 |
专业分类
安全科学 | 28篇 |
废物处理 | 30篇 |
环保管理 | 16篇 |
综合类 | 327篇 |
基础理论 | 132篇 |
污染及防治 | 139篇 |
评价与监测 | 3篇 |
灾害及防治 | 1篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 16篇 |
2021年 | 14篇 |
2020年 | 12篇 |
2019年 | 14篇 |
2018年 | 17篇 |
2017年 | 20篇 |
2016年 | 24篇 |
2015年 | 37篇 |
2014年 | 24篇 |
2013年 | 57篇 |
2012年 | 42篇 |
2011年 | 54篇 |
2010年 | 33篇 |
2009年 | 40篇 |
2008年 | 25篇 |
2007年 | 45篇 |
2006年 | 35篇 |
2005年 | 32篇 |
2004年 | 29篇 |
2003年 | 26篇 |
2002年 | 13篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 9篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
排序方式: 共有676条查询结果,搜索用时 250 毫秒
571.
The waste gas evolved from biodegradation of animal urine contains ammonia causing environmental concerns. A new and effective method for removing ammonia from such waste gas using reactive adsorption is presented. In the process, activated carbon impregnated with H2SO4(H2SO4/C) is employed. Ammonia in the waste gas reacts with H2SO4 on the adsorbent instantaneously and completely to form (NIL)2SO4. The H2SO4/C adsorbent is high in NH3 adsorption capacity and regenerable. The NH3 removal capacity of this regenerable adsorbent is more than 30 times that of the adsorbents used normally in the industry. The spent H2SO4/C is regenerated by flowing low-pressure steam through the adsorbent bed to remove the (NH4)2SO4 from the adsorbent. The regeneration by-product is concentrated (NH4)2SO4 solution, which is a perfect liquid fertilizer for local use. Re-soaking the activated carbon with H2SO4 solution rejuvenates the activity of the adsorbent. Thus the H2SOJC can be reused repeatedly. In the mechanism of this reactive adsorption process, trace of H20 in the waste gas is a required, which lends itself to treating ammonia gas saturated with moisture from biodegradation of animal urine. 相似文献
572.
573.
574.
575.
Metabolic responses of weeping willows to selenate and selenite 总被引:2,自引:0,他引:2
Goal, Scope and Background Selenium (Se) is one of the most widely distributed elements of the earth’s crust at low concentrations. The extensive use
of Se-containing chemicals due to anthropogenic activities has increased the ecological risk to environmental compartments.
Plants, under unfavorable environmental conditions, often increase the formation of reactive oxygen species (ROS), and consequently
plant antioxidant enzymatic systems have been proposed to be important in plant stress tolerance. The goal of this study was
to find out the metabolic responses of plants to Se, to provide quantitative information whether exogenous Se has a beneficial
role in plants, and to investigate the potential of vegetation management of Se for potential phytoremediation.
Material and Methods Pre-rooted plants of weeping willows (Salix babylonica L.) were grown hydroponically in growth chambers and treated with Na2SeO4 or Na2SeO3 at 24.0 ± 1°C for 168 h. Five different treatment concentrations were used, ranging from 0.44 to 8.72 mg Se/L for the treatments
exposed to SeO42− and from 0.50 to 10.0 mg Se/L for the treatments exposed to SeO32−, respectively. Transpiration rates, soluble protein contents and antioxidative enzyme activities of the plants were monitored
to evaluate toxicity from exogenous Se exposure. At the end of the study, total Se in the hydroponic solution was analyzed
by hydride generation-atomic fluorescence spectrometry (HG-AFS).
Results Both chemical forms of Se at low concentrations showed growth-promoting effects on plants. A significant decrease of transpiration
rates and of soluble protein contents of plants was observed at higher Se concentrations after 168 h of exposure. Measurable
change of superoxide dismutases (SOD) activity in leaves was only detected under high Se treatments. Catalase (CAT) activity
was significantly affected by the Se application. Slight change of peroxidase (POD) activity was measured in all treatments,
whereas significant inhibition of POD activity was detected for the plants exposed to SeO32− of 10.0 mg Se/L. Se-induced stress appeared in all treatments, thus resulting in measurable increase of glutathione peroxidase
(GSH-Px) activity of the plants. Although both chemical forms of Se were taken up by weeping willows efficiently, their uptake
rates were different.
Discussion Of all measured parameters, POD and CAT activities in leaves were noted the most sensitive indicator for the plants exposed
to SeO42− and SeO32−, respectively. Deleterious effects on plant physiological functions due to Se application were not observed over 168 h of
exposure. This is largely due to the fact that well-established antioxidant enzymatic systems in plants and higher activities
of GSH-Px largely reduced the negative effects on plants; SeO32− caused much more severe stress to plants than SeO42− at higher Se application rates. The uptake mechanisms between the two chemical species were quite different.
Conclusions Neither visible toxic symptoms nor metabolic lesions were observed at low concentrations of Se, probably due to the effective
established enzymatic systems in weeping willows. All selected parameters for toxicity determination were significantly correlated
to Se application, but metabolic responses of plants to SeO42− and SeO32− were quite different. GSH-Px in leaves was probably the principle enzyme responsible for stress reduction from Se exposure.
Due to their different chemical properties, weeping willows showed a faster uptake rate for SeO42− than for SeO32−.
Recommendations Exogenous Se has a beneficial role in plants and vegetation management of Se is a potential remediation strategy in cleaning
up Se-contaminated sites. Further investigation on the biochemical mechanism of Se metabolism will provide insight to the
specific interactions between Se and plants on the molecular level.
Perspectives Weeping willow has a sound potential for phytoremediation of Se-contaminated sediment and groundwater because the tree is
not only tolerant to Se but also uptakes chemical species from the environment. 相似文献
576.
The urban landscape is comprised of many land uses, none more intensively managed than turfgrass; however, quantification of nutrient losses from specific land uses within urban watersheds, specifically golf courses is limited. Nitrate (NO(3)-N) and dissolved reactive phosphorus (DRP) were measured on a golf course in Austin, TX, USA from April 1, 1998 to March 31, 2003. NO(3)-N and DRP concentrations measured in storm flow were significantly greater exiting the course compared to those entering the course. Significant differences were also measured in baseflow NO(3)-N concentrations. The measured loading from the course was 4.0kg NO(3)-Nha(-1)yr(-1) (11% of applied) and 0.66kg DRPha(-1)yr(-1) (8% of applied). The resulting concentrations contributed by the course were 1.2mgL(-1) NO(3)-N and 0.2mgL(-1) DRP. At these levels, NO(3)-N poses minimal environmental risk. However, the DRP concentration is twice the recommended level to guard against eutrophication. 相似文献
577.
578.
Cardoso NF Lima EC Pinto IS Amavisca CV Royer B Pinto RB Alencar WS Pereira SF 《Journal of environmental management》2011,92(4):1237-1247
The cupuassu shell (Theobroma grandiflorum) which is a food residue was used in its natural form as biosorbent for the removal of C.I. Reactive Red 194 and C.I. Direct Blue 53 dyes from aqueous solutions. This biosorbent was characterized by infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption/desorption curves. The effects of pH, biosorbent dosage and shaking time on biosorption capacities were studied. In acidic pH region (pH 2.0) the biosorption of the dyes were favorable. The contact time required to obtain the equilibrium was 8 and 18 h at 298 K, for Reactive Red 194 and Direct Blue 53, respectively. The Avrami fractionary-order kinetic model provided the best fit to experimental data compared with pseudo-first-order, pseudo-second-order and chemisorption kinetic adsorption models. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Radke-Prausnitz isotherm models. For both dyes the equilibrium data were best fitted to the Sips isotherm model. 相似文献
579.
580.
傍河型水源井氨氮阻断与去除工程设计案例分析 总被引:1,自引:0,他引:1
针对沈阳市傍河型水源地的氨氮(NH+4-N)污染问题,通过野外研究区的水文地质调查,在查明研究区NH+4-N污染特征的基础上,结合室内批试验、柱实验和数值模拟,筛选出最佳的NH+4-N去除方案,提出了研究区渗透反应格栅(PRB)构建方案,并成功构建了示范工程尺度的PRB,用以去除地下水中的NH+4-N污染.室内批实验和柱实验表明,利用微生物硝化作用结合沸石的吸附作用去除地下水中NH+4-N是可行的.通过对研究区水质数值模拟,发现构建有一定弧度的PRB能最大限度的保护水源井.在PRB的构建过程中,利用高压旋喷技术和旋挖技术解决了大深度(30 m)PRB的构建问题,且PRB建成运行监测表明,示范工程尺度的PRB能有效阻断和去除地下水中NH+4-N. 相似文献