全文获取类型
收费全文 | 14311篇 |
免费 | 140篇 |
国内免费 | 422篇 |
专业分类
安全科学 | 194篇 |
废物处理 | 1032篇 |
环保管理 | 1586篇 |
综合类 | 2102篇 |
基础理论 | 4014篇 |
环境理论 | 6篇 |
污染及防治 | 3303篇 |
评价与监测 | 1403篇 |
社会与环境 | 1178篇 |
灾害及防治 | 55篇 |
出版年
2024年 | 4篇 |
2023年 | 70篇 |
2022年 | 169篇 |
2021年 | 211篇 |
2020年 | 121篇 |
2019年 | 120篇 |
2018年 | 1588篇 |
2017年 | 1521篇 |
2016年 | 1400篇 |
2015年 | 315篇 |
2014年 | 318篇 |
2013年 | 504篇 |
2012年 | 849篇 |
2011年 | 1688篇 |
2010年 | 995篇 |
2009年 | 852篇 |
2008年 | 1184篇 |
2007年 | 1546篇 |
2006年 | 295篇 |
2005年 | 218篇 |
2004年 | 168篇 |
2003年 | 162篇 |
2002年 | 199篇 |
2001年 | 76篇 |
2000年 | 60篇 |
1999年 | 33篇 |
1998年 | 26篇 |
1997年 | 19篇 |
1996年 | 10篇 |
1995年 | 21篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1988年 | 3篇 |
1985年 | 3篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1970年 | 2篇 |
1967年 | 4篇 |
1966年 | 4篇 |
1965年 | 2篇 |
1964年 | 6篇 |
1962年 | 3篇 |
1959年 | 4篇 |
1958年 | 15篇 |
1957年 | 5篇 |
1955年 | 2篇 |
1935年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
The bromination of five selected pharmaceuticals (metoprolol, naproxen, amoxicillin, phenacetin, and hydrochlorothiazide) was studied with these compounds individually dissolved in ultra-pure water. The apparent rate constants for the bromination reaction were determined as a function of the pH, obtaining the sequence amoxicillin > naproxen ? hydrochlorothiazide ≈ phenacetin ≈ metoprolol. A kinetic mechanism specifying the dissociation reactions and the species formed for each compound according to its pKa value and the pH allowed the intrinsic rate constants to be determined for each elementary reaction. There was fairly good agreement between the experimental and calculated values of the apparent rate constants, confirming the goodness of the proposed reaction mechanism.In a second stage, the bromination of the selected pharmaceuticals simultaneously dissolved in three water matrices (a groundwater, a surface water from a public reservoir, and a secondary effluent from a WWTP) was investigated. The pharmaceutical elimination trend agreed with the previously determined rate constants. The influence of the main operating conditions (pH, initial bromine dose, and characteristics of the water matrix) on the degradation of the pharmaceuticals was established. An elimination concentration profile for each pharmaceutical in the water matrices was proposed based on the use of the previously evaluated apparent rate constants, and the theoretical results agreed satisfactorily with experiment. Finally, chlorination experiments performed in the presence of bromide showed that low bromide concentrations slightly accelerate the oxidation of the selected pharmaceuticals during chlorine disinfection. 相似文献
992.
Taking into account current environmental concerns, the main objective of this work focused a national inventory aiming to estimate the amount of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) released in Portugal in 2006. The methodology used was based on the Standardized Toolkit for Identification and Quantification of Dioxins and Furan Releases, developed by UNEP Chemicals, in 2005. The method allows the assessment of the amount of PCDD/PCDF released into the environment along five vectors involving air, water, land, products and residues. Facing some difficulties mainly regarding to the availability of data for some activities known to produce PCDD/PCDF, three scenarios (Sc1 to Sc3) corresponding to lower, central and upper estimates were established. The Sc1 scenario (lower estimate) includes the situations where in case of doubt or scarce information, reduced or none emission values were assumed, Sc2 refers to a central estimate, which is believed to be the most realistic for the Portuguese situation, while Sc3 corresponds to the worst case (upper estimate). The results obtained pointed out that the total amount of PCDD/PCDF emitted in Portugal during the period under analysis was in the range of 51.2-217.9 g TEQ year−1, with the most likely value of 95.2 g TEQ year−1 achieved under the Sc2 scenario. This study also showed that the methodology developed by UNEP Chemicals is a very simple one, and the main difficulty is the availability of data. The main indicators calculated in this study were 8.98 μg TEQ/(year person) by taking into account the total amount of PCDD/PCDF released, and 3.63 μg TEQ/(year person) when only air emissions were considered. 相似文献
993.
Microcosm experiments to control anaerobic redox conditions when studying the fate of organic micropollutants in aquifer material 总被引:1,自引:0,他引:1
994.
Polybromodiphenyl ethers (PBDEs) are one of the many toxic chemicals present in the environment and in the food we eat every day, being fish one of the main sources of persistent organic pollutants in our diet; like other lipid-related contaminants, they are of concern since they can bioaccumulate and biomagnify through the trophic chain. We published a study focused on the dietary uptake of dioxins and furans (PCDD/Fs) and dioxin-like polychlorobiphenyls (dl-PCBs) in a set of samples of Spanish farmed turbot (Blanco et al., 2007). In the present paper, we extend the study to PBDEs to provide more information about the uptake and transfer from feed to fish of halogenated contaminants. PBDEs in the feeds (2.35-4.76 ng g(-1)) were reflected in turbot fillets (0.54-2.05 ng g(-1)): predominant congeners were tetra-BDE 47, penta-BDEs 99 and 100. It is remarkable that tetra-BDE 49, accounting for only 2% in the feed, contributed to 15% of total PBDEs in turbot fillets. Dietary net accumulation values, 30-45%, showed that tri-, tetra-, penta- and hexa-BDEs were as efficiently transferred into turbot as dl-PCBs and tetra- and penta-chlorinated PCDD/Fs. Lipid-normalized biomagnification factors relating concentration in fish and in feed, BMFs>1 were obtained, except for BDE 209. BDE 49 accumulation, 90%, was possibly contributed by metabolism of higher brominated BDEs. Implication in aquaculture management is a need for uncontaminated fish feed to offer safe products. 相似文献
995.
Biofilm responses to marine fish farm wastes 总被引:1,自引:0,他引:1
Sanz-Lázaro C Navarrete-Mier F Marín A 《Environmental pollution (Barking, Essex : 1987)》2011,159(3):825-832
The changes in the biofilm community due to organic matter enrichment, eutrophication and metal contamination derived from fish farming were studied. The biofilm biomass, polysaccharide content, trophic niche and element accumulation were quantified along an environmental gradient of fish farm wastes in two seasons. Biofilm structure and trophic diversity was influenced by seasonality as well as by the fish farm waste load. Fish farming enhanced the accumulation of organic carbon, nutrients, selenium and metals by the biofilm community. The accumulation pattern of these elements was similar regardless of the structure and trophic niche of the community. This suggests that the biofilm communities can be considered a reliable tool for assessing dissolved aquaculture wastes. Due to the ubiquity of biofilms and its wide range of consumers, its role as a sink of dissolved wastes may have important implications for the transfer of aquaculture wastes to higher trophic levels in coastal systems. 相似文献
996.
997.
González-Santiago O Badillo-Castañeda CT Kahl JD Ramírez-Lara E Balderas-Renteria I 《Journal of the Air & Waste Management Association (1995)》2011,61(5):573-579
The Monterrey Metropolitan Area (MMA) is the third largest city in Mexico. Few studies have been carried out regarding its air pollution. The aim of this study was to analyze the temporal behavior of PM10 (particulate matter < or =10 microm in aerodynamic diameter). Data reported by the "Sistema Integral de Monitoreo Ambiental" (Integrated Environmental Monitoring System) network from 2006 to 2008 were used. PM10 levels were compared among the stations by year, season, and day of week. A bootstrap technique was used to obtain subsamples to which Student's t test and ANOVA were applied. PM10 levels were high and exceeded the annual limit of 50 microg/m3 set up by the Mexican standard Norma Oficial Mexicana NOM-025-SSA1-1993. These levels could have serious health effects. The southwest zone of MMA had the highest levels of PM10 during the period studied. Winter was the most polluted season, and summer was the least polluted season. Thursday and Friday were the most polluted days, and Sunday was the least polluted day. The hours with the highest levels of PM10 were 8:00 to 10:00 a.m., whereas nighttime hours were the cleanest. 相似文献
998.
分析了石灰石—石膏湿法脱硫系统中烟气系统、吸收塔系统、石灰石系统、石膏脱水系统、废水处理系统等在运行中存在问题,并提出了相应的对策。 相似文献
999.
Mehmet Berkun Egemen Aras Tugce Anılan 《Journal of Material Cycles and Waste Management》2011,13(4):305-313
As an economically developing country, Turkey has very well operated integrated solid waste management applications structured
on modern facilities, besides over 2,000 scattered open dump areas in the country. Integrated waste management applications
seem eligible for the metropolitan cities like Istanbul and Izmit (Kocaeli). Attempts have not been encouraging for the scattered
regional settlements using central storage sites due to financial shortages and received rejections from nearby settlements.
Small-scale compact solid waste management systems with materials recycling and composting can be more suitable alternatives
in the small-scale regional settlements. The major constituents of municipal solid waste are organic in nature and approximately
a quarter of municipal solid waste is recyclable. Although paper, including cardboard, is the main constituent, the composition
of recyclable waste varies strongly by the source or the type of collection point. Solid wastes need primary treatment in
order to be suitable for incineration and composting. Turkey needs to give more emphasis on the usage of modern solid waste
removal technologies to overcome the overgrowing solid waste disposal problems. 相似文献
1000.
The circular economy has been developing rapidly in recent years in China. A legislative system has been created to provide
legal protection for the development of a circular economy, including a series of price and tax measures in the waste management
area. These measures form the basic foundation for promoting better waste management under the circular economic model. Many
challenges, however, remain. For instance, the legal system needs to incorporate more sophisticated science, and China lacks
key waste treatment technology that could support the further development of a circular economy. There is also a need to educate
the public about the concept of the circular economy and its benefits. Specific suggestions are made for the development and
implementation of the circular economic model. 相似文献