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951.
952.
An assessment of endocrine disrupting activity changes during wastewater treatment through the use of bioassays and chemical measurements. 总被引:1,自引:0,他引:1
J?rg E Drewes Jocelyn Hemming Sarah J Ladenburger James Schauer William Sonzogni 《Water environment research》2005,77(1):12-23
The objective of this study was to assess the removal efficiencies of secondary wastewater treatment processes for compounds causing endocrine disrupting activity. The study used bioassays and chemical measurements, such as gas chromatography with mass spectrometry and enzyme immunosorbent assays. A total of seven full-scale water reclamation facilities using different unit operations and two pilot-scale membrane bioreactors were examined. Findings of this study imply that estrogenic disrupting activity in primary effluent is mainly caused by two steroidal hormones (17beta-estradiol and estriol) and, to a lesser extent, by synthetic chemicals, such as bisphenol A, 4-nonylphenol, and 4-tert-octylphenol. During secondary treatment, steroidal hormones were removed to a higher degree than nonylphenol and bisphenol A. The total estrogenic activity was removed by an average of 96%. The remaining concentrations of targeted steroids in secondary effluents, except for estriol, still had the potential to elicit a positive response in the human breast cell cancer assay. For the majority of facilities, the remaining activity was likely attributed to residual concentrations of two steroidal hormones (17beta-estradiol and estriol). 相似文献
953.
The global re-cycling of persistent organic pollutants is strongly retarded by soils 总被引:12,自引:0,他引:12
Ockende WA Breivik K Meijer SN Steinnes E Sweetman AJ Jones KC 《Environmental pollution (Barking, Essex : 1987)》2003,121(1):75-80
'Persistent organic pollutants' (POPs) are semi-volatile, mobile in the environment and bioaccumulate. Their toxicity and propensity for long-range atmospheric transport (LRAT) has led to international bans/restrictions on their use/release. LRAT of POPs may occur by a 'single hop' or repeated temperature-driven air-surface exchange. It has been hypothesised that this will result in global fractionation and distillation-with condensation and accumulation in polar regions. Polychlorinated biphenyls (PCBs)--industrial chemicals banned/restricted in the 1970s--provide a classic illustration of POP behaviour. A latitudinally-segmented global PCB inventory has been produced, which shows that approximately 86% of the 1.3 x 10(6) tonnes produced was used in the temperate industrial zone of the northern hemisphere. A global survey of background surface soils gives evidence for 'fractionation' of PCBs. More significantly, however, very little of the total inventory has 'made the journey' via primary emission and/or air-surface exchange and LRAT out of the heavily populated source regions, in the 70 years since PCBs were first produced. Soils generally occlude PCBs, especially soils with dynamic turnover of C/bioturbation/burial mechanisms. This limits the fraction of PCBs available for repeated air-soil exchange. The forested soils of the northern hemisphere, and other C-rich soils, appear to be playing an important role in 'protecting' the Arctic from the advective supply of POPs. Whilst investigations on POPs in remote environments are important, it is imperative that researchers also seek to better understand their release from sources, persistence in source regions, and the significant loss mechanisms/global sinks of these compounds, if they wish to predict future trends. 相似文献
954.
Jurvelin JA Edwards RD Vartiainen M Pasanen P Jantunen MJ 《Journal of the Air & Waste Management Association (1995)》2003,53(5):560-573
Personal 48-hr exposures of 15 randomly selected participants as well as microenvironment concentrations in each participant's residence and workplace were measured for 16 carbonyl compounds during summer-fall 1997 as a part of the Air Pollution Exposure Distributions within Adult Urban Populations in Europe (EXPOLIS) study in Helsinki, Finland. When formaldehyde and acetaldehyde were excluded, geometric mean ambient air concentrations outside each participant's residence were less than 1 ppb for all target compounds. Geometric mean residential indoor concentrations of carbonyls were systematically higher than geometric mean personal exposures and indoor workplace concentrations. Additionally, residential indoor/outdoor ratios indicated substantial indoor sources for most target compounds. Carbonyls in residential indoor air correlated significantly, suggesting similar mechanisms of entry into indoor environments. Overall, this study demonstrated the important role of non-traffic-related emissions in the personal exposures of participants in Helsinki and that comprehensive apportionment of population risk to air toxics should include exposure concentrations derived from product emissions and chemical formation in indoor air. 相似文献
955.
956.
为探讨污水深度处理和同步获取产油微藻的可行性,建立光生物反应器,应用微拟球藻去除污水和中水中的氮磷,并分析不同浓度的Fe3+和Zn2+离子对微藻的生长和油脂积累的影响,从而在净化污水的同时培养微藻获得富油生物质。结果表明,该藻对污水氮磷具有较强的去除能力,可在13 d内,去除水体中96%的氨氮和94%的磷,同时化学需要氧量(COD)的去除率可达72.9%。在生活污水中培养至第16天,微藻的细胞密度可达4.55×106 cell/mL。Fe3+浓度对微拟球藻的生长具有显著影响(P6 cell/mL。该研究以中水和生活污水为基质培养微拟球藻,同时获取微藻油脂,为污水中氮磷的去除和能源的同步获取提供了新途径。 相似文献
957.
958.
959.
The photocatalytic oxidation of phenanthrene was investigated in aqueous TiO2 suspensions under UV light irradiation. Chemical oxygen demand (COD) measurements, UV-Vis spectrophotometer, IR spectrometer and gas chromatography-mass spectrometry (GC-MS) analytical techniques were used to monitor the reaction process. Some factors affecting the photodegradation rate were studied and some aromatic intermediates were detected during the reaction process. Fast and complete mineralization of phenanthrene was achieved in this reaction system. 相似文献
960.
The storage of nitrate by phytoplankton cells during the early phases of upwelling was studied in coastal stations off northern
Spain (southern Bay of Biscay) between 1990 and 1994. In this region, a persistent upwelling during summer is characterised
by intermittent pulses of variable intensity, and increased nutrient concentrations in the surface layer. The main effect
of an upwelling pulse on phytoplankton distribution is the shifting of the chlorophyll a and primary production maxima to near the surface. When the upwelling relaxes, thermal stratification of the water column
occurs, and a distinct subsurface chlorophyll maximum develops below the production maximum. An accumulation of intracellular
nitrate characterized the early phases of upwelling (mean = 2.73 μmol N m−3), maximum concentrations being attained at depths where biomass and production values were moderate. In contrast, phytoplankton
cells from non-upwelling situations contained significantly lower concentrations of intracellular nitrate (mean = 0.17 μmol
N m−3). The variations in the intracellular pool of nitrate may result from the differential allocation of resources within the
cell as a result of variations in the energy available, since the uptake and assimilation of nitrate is a relatively expensive
process involving several enzymatic systems. We hypothesize that nitrate storage by phytoplankton cells is characteristic
of early phases of upwelling and is linked to patterns of carbon fixation. Average nitrogen budgets for upwelling and non-upwelling
situations indicate that intracellular nitrate reserves are not responsible for maintaining high phytoplankton growth rates,
since they only account for <2% of daily primary production during upwelling events.
Received: 28 August 1996 / Accepted 3 December 1996 相似文献