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801.
Spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in sediments from Daya Bay, South China 总被引:2,自引:0,他引:2
Wen Yan Jisong Chi Weixia Huang 《Environmental pollution (Barking, Essex : 1987)》2009,157(6):1823-1830
The spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) has been investigated in Daya Bay, China. The total concentration of the 16 USEPA priority PAHs in surface sediments ranged from 42.5 to 158.2 ng/g dry weight with a mean concentration of 126.2 ng/g. The spatial distribution of PAHs was site-specific and combustion processes were the main source of PAHs in the surface sediments. Total 16 priority PAH concentration in the cores 8 and 10 ranged from 77.4 to 305.7 ng/g and from 118.1 to 319.9 ng/g respectively. The variation of the 16 PAH concentrations in both cores followed the economic development in China very well and was also influenced by input pathways. Some of the PAHs were petrogenic in core 8 while pyrolytic source was dominant in core 10. In addition, pyrolytic PAHs in both cores were mainly from the coal and/or grass and wood combustion. 相似文献
802.
以眯唑类[PF6]^-型离子液体1-丁基-3-甲基咪唑六氟磷酸盐([Bmim][PF6])、1-己基-3-甲基咪唑六氟磷酸盐([Hmim][PF6])和1-辛基-3-甲基咪唑六氟磷酸盐([Omim][PF6])对苯胺、对氯苯胺等7种胺类化合物的萃取,考察了溶液初始浓度、相比、盐类、pH及离子液体眯唑基团上取代烷基对萃取平衡的影响,并研究了萃取过程的热效应。实验结果表明:溶液初始浓度对分配系数影响较小;相比10:1是离子液体对胺类化合物的溶解饱和临界点,当相比大于10:1时,分配系数降低;NaCl、K2SO4可以增大萃取分配系数,ZnSO4对分配系数几乎没有影响;pH增加,分配系数增大;离子液体对不同取代基的胺类萃取能力有较大的差异,咪唑基团上取代烷基的长度对不同胺类物质的分配系数影响较显著;萃取过程属于焓增大的吸热过程。 相似文献
803.
Baoning Zhang Fan Meng Chune Shi Fuquan Yang Deyong Wen Jonatan Aronsson Philip K. Gbor James J. Sloan 《Atmospheric environment (Oxford, England : 1994)》2009,43(13):2204-2212
The atmospheric fate of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) was simulated for the year 2000 in North America using a SMOKE/CMAQ-based chemical transport model that was modified for this purpose. The 1999 USEPA emission inventories of PCDD/Fs and criteria pollutants were used. The 1995 Canadian emission inventory of criteria pollutants and the 1995 Canadian area source emissions for PCDD/Fs were used with the 2000 Canadian point source emissions. Modifications to CMAQ involved coupling it with dual organic matter (OM) absorption and black carbon (BC) adsorption models to calculate PCDD/F gas–particle partitioning. The model satisfactorily reproduced the particle bound fractions at all rural sites for which there were measured data and across the whole domain, the modeled vs. measured differences in particle bound fractions were less than 20% for nearly all congeners. The model predicted ambient air PCDD/F concentrations were also consistent with measurements. Simulated deposition fluxes were within 58% of direct measurements. PCDD/F atmospheric depositions to each of the Great Lakes were estimated for the year 2000. The results indicate that approximately 76% of the total deposition of PCDD/Fs to the Great Lakes (in W-TEQ, or toxic equivalent units as defined by the World Health Organization) is attributed to PCDD/Fs absorbed into OM in aerosol. For all of the lakes, more than 92% of all deposition is particle phase wet deposition and only 5–8% is particle phase dry deposition. Wet deposition from the gas phase is negligible. Of the 17 toxic PCDD/F congeners, the Cl4–5DD/F compounds contribute approximately 70% to the total atmospheric deposition to the Great Lakes. The seasonal changes in the PCDD/F deposition flux track variations in ambient temperature. 相似文献
804.
Chang CS Yen JH Chen WC Wang YS 《Journal of environmental science and health. Part. B》2012,47(1):13-21
This investigation was undertaken to examine the dissipation rate of pyriproxyfen as well as the change in the soil bacterial community. Residues of pyriproxyfen were measured using high performance liquid chromatography (HPLC) and the changes in bacterial community were determined by comparing the 16S rDNA bands on patterns by denaturing gradient gel electrophoresis (DGGE). The dissipation of pyriproxyfen was affected by both the concentration applied and incubation temperature. Lower concentrations (1 mg Kg(-1)) and higher incubation temperatures (30 and 40°C) showed more rapid dissipation rates. The population of microbial community decreased rapidly after incubation with 10 mg Kg(-1) of pyriproxyfen for 91 days, indicating the toxicity of pyriproxyfen toward bacterial communities in a closed soil ecosystem. Lower concentrations of pyriproxyfen showed less toxicity toward the microbial community. From cluster analysis, the structure of the bacterial community showed roughly a 60 % similarity throughout the experiment period in the control experiment, indicating the stability within soil microbiota without chemical agitation. However, the similarity was lower than 50 % both in the one and 10 mg Kg(-1) of insecticide pyriproxyfen spiked experiment, indicating the soil bacterial community changed after the insecticide pyriproxyfen was applied. 相似文献
805.
806.
海洲香薷种群微量金属元素的累积分布特征 总被引:3,自引:0,他引:3
分析了大冶铜绿山铜矿区海洲香薷种群几种微量金属元素的吸收累积和分布特征、生殖分配( RA)特征及植物与土壤元素的关系 ,并就该植物对铜等金属元素的耐受性进行了初步探讨。结果显示 ,该植物生长的土壤重金属元素含量很高 ,其中 Cu的含量 (平均 5 843μg/ g)是背景值的 2 0 0多倍。 Cu、Mn、Zn、Cd、Pb几种微量金属元素的含量 ,以 Cu最高 ,Cd最低。几种元素的大小顺序表现为 :Cu>Mn>Zn>Pb>Cd。不同元素在植物不同构件的含量为 :Cu,根 >花 >叶 >茎 ;Mn,叶 >根 >花 >茎 ;Zn,叶 >花 >茎 >根 ;Cd,叶 >花 >根 >茎 ;Pb,根 >叶 >茎 >花。这几种元素的 RA范围为 10 %~ 40 % ,平均为 2 4.97% ;生物量 RA为 2 6.5 %。植物铜元素与土壤显著正相关。海洲香薷对铜等金属具有很强的耐受性。 相似文献
807.
Residential Preferences for River Network Improvement: An Exploration of Choice Experiments in Zhujiajiao,Shanghai, China 总被引:1,自引:0,他引:1
River networks have both ecological and social benefits for urban development. However, river networks have suffered extensive destruction as a result of urbanization and industrialization, especially in China. River restoration is a growth business but suffers poor efficiency due to a lack of social understanding. Assessing the benefits of river system restoration and recognizing public preferences are critical for effective river ecosystem restoration and sustainable river management. This study used a choice experiment with a multinomial logit model and a random parameter logit model to assess respondents’ cognitive preferences regarding attributes of river networks, and their possible sources of heterogeneity. Results showed that riverfront condition was the attribute most preferred by respondents, while stream morphology was the least preferred. Results also illustrated that the current status of each of three river network attributes was not desirable, and respondents would prefer a river network with a “branch pattern,” that is “limpid with no odor,” and “accessible with vegetation.” Estimated willingness to pay was mainly affected by household monthly income, residential location, and whether respondents had household members engaged in a water protection career. The assessment results can provide guidance and a reference for managers, sponsors, and researchers. 相似文献
808.
铁路工程建设可持续发展战略的研究 总被引:1,自引:2,他引:1
提出了铁路建设走可持续发展之路,论证了铁路工程建设、环境与地质灾害三者的相互关系,阐述了在铁路工程建设的各个环节树立环境保护和防灾减灾的重要性。 相似文献
809.
810.