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531.
A moving bio-film (MB), made from the inner tube of used tyres was applied in a conventional-aerobic-SBR for increasing the system efficiency and quality of bio-sludge due to good sedimentation (the density of 1.925+/-0.21 g/cm(3)), non-biodegradability and re-usability of the media without any regeneration. The total bio-sludge mass of the MB-aerobic-SBR was about 30% higher than that of the conventional-aerobic-SBR resulting in a reduction of the F/M value of the system and amount of suspended bio-sludge waste. The amount of suspended bio-sludge waste, SVI and SRT of the MB-aerobic-SBR under a low organic loading of 80+/-9.3g BOD(5)/m(3)-d were 1,485+/-146 mg/d, 51+/-3.7 ml/g and 10.1+/-5.1 days, respectively while they were 1,800+/-152 mg/d, 69+/-4.0 ml/g and 8.3+/-5.3 days, respectively in the conventional-aerobic-SBR. The BOD(5), TKN and TP removal efficiencies of the MB-aerobic-SBR were about 1-2, 2-3 and 10-12% higher, respectively, than that of the conventional-aerobic-SBR. Also, the BOD(5) and COD removal efficiencies of the MB-aerobic-SBR were higher than 95% even when the system was operated with synthetic wastewater containing 800 mg/l BOD(5) under a very low HRT of 1.5 days (organic loading of 528+/-50.8 g BOD(5)/m(3)-d). The effluent BOD(5), COD, total kjeldahl nitrogen, total phosphorus and suspended solids of the MB-aerobic-SBR under a high organic loading of 528+/-50.8 g BOD(5)/m(3)-d were 45+/-5.1, 37+/-3.6, 4.1+/-1.0, 1.5+/-0.80 and 41+/-2mg/l, respectively. 相似文献
532.
太湖氮磷大气干湿沉降时空特征 总被引:10,自引:0,他引:10
为了探索太湖氮磷营养盐干湿沉降特征及对太湖营养盐输入的贡献,于2011年不同季节采集太湖不同位点的大气干湿沉降样品,分析干湿沉降中氮(N)和磷(P)的形态和沉降量。研究结果表明,输入太湖的磷以干沉降为主,而氮以湿沉降为主。在太湖干沉降中总无机氮(TIN)占总氮(TN)的77.1%,溶解性磷(DIP)占总磷(TP)的77.9%。干沉降中TIN主要以NH+4-N为主。西太湖是TN与TP通过大气干湿沉降输入太湖的最高湖区。太湖全年大气TN沉降总量为20 978 t,TP沉降总量为1 268 t,因此,氮磷大气干湿沉降是太湖营养盐输入的重要来源之一。 相似文献
533.
This paper presents an air-quality surveillance system designed to detect the occurrence of air pollutant concentrations greater
than a reference level in an urban area. The system is integrated by an air-quality monitoring network and atmospheric dispersion
models simulations. An objective methodology to design an urban air-quality monitoring network is proposed. This methodology
is based on the analysis of air-quality modelling results. The procedure is applied to design an air-quality monitoring network
to control NO
x
concentration levels in Buenos Aires City. Results indicate that six monitors will detect the occurrence of concentration
greater than the air-quality guidelines with an efficiency of about 67%. Once a violation is detected, results of atmospheric
dispersion models will help in the determination of affected areas. Four possible examples are included to illustrate the
assistance that the results of atmospheric dispersion models can bring to a better estimation of possible affected areas in
the city. Combining these results with the last census data, an estimation of the inhabitants possibly exposed is obtained. 相似文献
534.
Thöni L Seitler E Meier M Zürcher F Hertz J 《Environmental monitoring and assessment》2008,138(1-3):207-218
This study presents the results of the analyses of Cd, Pb, cations and anions present in precipitation and dust at a pre-alpine
and a suburban site in Switzerland in the period from 1988 to 2003. The aim of these measurements was to monitor the success
of measures taken to diminish pollutant emissions. No change was found for Ca2+, K+, Na+ and Mg2+ loads – in line with expectations, as no reducing measures had been taken. Statistically significant and largely decreasing
values (50–90%) were found for Cl− and Cd (linked to the fitting of filters in incineration plants), Pb (unleaded petrol), (diminishing the use of mineral oil with high S content), and the proton (lower HCl and SO2 emissions). A smaller decrease (up to 30%) or none was registered for oxidised nitrogen components (fitting cars with catalytic
converters, but an increase in numbers of cars and trucks). No significant change was found for NH3 as farming techniques had undergone no major changes. The long-term measurements show that the measures taken to reduce emissions
were successful. A shorter monitoring period would have been misleading owing to data variability and temporary incidents
e.g. amount of precipitation. 相似文献
535.
536.
水暴露下氟在西伯利亚鲟稚鱼硬骨和软骨中的积累和消除 总被引:3,自引:1,他引:2
采用静态水暴露试验方法,设置0.26(对照)、3.1、7.8、18.7、51.8mg·L-1氟离子(F-)5个试验组暴露西伯利亚鲟稚鱼,暴露90d后转移至清水中培养30d,检测了这2个阶段鱼体硬骨和软骨中氟离子含量,探讨了氟离子在西伯利亚鲟稚鱼硬骨和软骨中的积累与消除规律,以及氟离子对鱼体生长的影响.结果表明,随着氟离子浓度的增加和暴露时间的延长,氟在西伯利亚鲟稚鱼硬骨和软骨中的含量显著增加,暴露90d时各暴露组硬骨和软骨中氟含量均显著高于对照组;西伯利亚鲟稚鱼暴露在较高浓度氟离子(7.8、18.7和51.8mg·L-1)中90d,生长速度(体重)显著下降;经过30d清水培养后,较高浓度暴露组(18.7和51.8mg·L-1)西伯利亚鲟稚鱼硬骨的氟含量显著下降.由此结论:氟在西伯利亚鲟稚鱼硬骨和软骨组织中具有较高的生物蓄积作用;转移至清水中饲养后,蓄积的高浓度的氟可从硬骨中排出. 相似文献
537.
This paper focused on the factors affecting the respiration rate of the digestate taken from a continuous anaerobic two-stage process treating the organic fraction of municipal solid waste (OFMSW). The process involved a hydrolytic reactor (HR) that produced a leachate fed to a submerged anaerobic membrane bioreactor (SAMBR). It was found that a volatile solids (VS) removal in the range 40-75% and an operating temperature in the HR between 21 and 35 °C resulted in digestates with similar respiration rates, with all digestates requiring 17 days of aeration before satisfying the British Standard Institution stability threshold of 16 mg CO2 g VS−1 day−1. Sanitization of the digestate at 65 °C for 7 days allowed a mature digestate to be obtained. At 4 g VS L−1 d−1 and Solid Retention Times (SRT) greater than 70 days, all the digestates emitted CO2 at a rate lower than 25 mg CO2 g VS−1 d−1 after 3 days of aeration, while at SRT lower than 20 days all the digestates displayed a respiration rate greater than 25 mg CO2 g VS−1 d−1. The compliance criteria for Class I digestate set by the European Commission (EC) and British Standard Institution (BSI) could not be met because of nickel and chromium contamination, which was probably due to attrition of the stainless steel stirrer in the HR. 相似文献
538.
Follador M Leip A Orlandini L 《Environmental pollution (Barking, Essex : 1987)》2011,159(11):3233-3242
We investigated the effects of the agricultural Cross Compliance measures for European cultivated lands, focusing on nitrogen (N) fluxes from corn fields. Four scenarios have been designed according to some conservation farming practices, namely no-till, max manure, catch crop and N splitting. Results indicated that (1) in the no-till scenario the N2O fluxes are decreased during the first simulated years, with a return to default fluxes in following years; no-till particularly decreased N2O emission in the dryer and colder simulation spatial units (HSMUs); (2) the no-till and the N splitting scenarios slightly increased the N surplus because of a decrease in plant uptake; (3) introducing a rotation with alfalfa decreased the N leaching in the corn crops following the catch crops; and (4) the application of fertilizer and manure during the cold and wet seasons led to an increase of N leaching. 相似文献
539.
We are fertilizing a thicket with 0, 10, 20 and 50 kg nitrogen (N) ha−1 yr−1 in central Spain. Here we report changes in cover, pigments, pigment ratios and FvFm of the N-tolerant, terricolous, lichen Cladonia foliacea after 1-2 y adding N in order to study its potential as biomarker of atmospheric pollution. Cover tended to increase. Pigments increased with fertilization independently of the dose supplied but only significantly with soil nitrate as covariate. β-carotene/chlorophylls increased with 20-50 kg N ha−1 yr−1 (over the background) and neoxanthin/chlorophylls also increased with N. (Neoxanthin+lutein)/carotene decreased with N when nitrate and pH seasonalities were used as covariates. FvFm showed a critical load above 40 kg N ha−1 yr−1. Water-stress, iron and copper also explained variables of lichen physiology. We conclude that this tolerant lichen could be used as biomarker and that responses to N are complex in heterogeneous Mediterranean-type landscapes. 相似文献
540.
Pleijel H 《Environmental pollution (Barking, Essex : 1987)》2011,159(4):897-902
This study considered effects of reduced [O3] on wheat yield. Open-top chamber charcoal filtered air treatments were compared with non-filtered treatments for field-grown wheat. 30 experiments meeting requirements were found, representing nine countries in North America, Europe and Asia. 26 experiments reported improved yield and 4 experiments reduced yield by filtration, a significant positive effect. Average yield improvement was 9%. Average daytime [O3] was reduced by filtration from 35 to 13 nmol mol−1. Filtration efficiency was 63% for O3 and 56% for SO2. For NOx it was observed that NO2 was reduced and NO increased by filtration. Thus, filters convert NO2 to NO. Most experiments reported low or very low [SO2] and [NOx]. Thus, O3 can be concluded to be the main phytotoxic component in the experiments. Elevated [NO2] was observed in one experiment. The conclusion is that current [O3] over large parts of the world adversely affect wheat yield. 相似文献