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61.
Thermoplasticization of High Amylose Starch by Chemical Modification Using Reactive Extrusion 总被引:2,自引:0,他引:2
Jacqueline Stagner Vanessa Dias Alves Ramani Narayan Adelaide Beleia 《Journal of Polymers and the Environment》2011,19(3):589-597
Modified thermoplastic high amylose starch (MTPS) was synthesized by reactive extrusion in the presence of maleic anhydride
(MA) as an esterification agent in a twin-screw extruder. The objective of this work was the preparation of reactive thermoplastic
starch in the presence of glycerol and with different amounts of maleic anhydride (MA) and free-radical initiator, in order
to improve processability and reactivity. The concentration of MA added varied from 2 to 6 wt% (of starch + glycerol), and
the free-radical initiator, 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane, also called Luperox 101, varied from 0.1 to 0.5
wt% (of starch + glycerol). Characterization of maleated thermoplastic starch was performed using dynamic light scattering
and thermal analysis. Further, proof of chemically modified extrudate was determined by Fourier transform infrared spectroscopy
and by soxhlet extraction with acetone. The modified high amylose corn starch (20 or 30% glycerol) could be pelletized and
gave pellets that were more transparent than thermoplastic starches not modified with maleic anhydride. There was negligible
change in hydrodynamic radius as the percentage of maleic anhydride increased. However, as the percentage of Luperox 101 increased,
the hydrodynamic radius decreased. It could be inferred that the molecular weight decreased as the percentage of free-radical
initiator increased. Using the maximum temperature in the extrusion process of 165 °C instead of 135 °C caused a decrease
in the hydrodynamic radius, due to the high influence of the temperature profile on the molecular weight of the thermoplastic
starch. The MTPS samples presented higher melting temperatures compared to TPS samples. The soxhlet studies indicated that
the plasticizer, glycerol, was chemically linked to the starch. Using the maximum temperature of 165 °C versus 135 °C in the
extrusion temperature profile resulted in more interaction between glycerol and starch. 相似文献
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Cíntia Melazo Dias Kristina Stenström Igor Luiz Bacelar Leão Roberto Ventura Santos Iêda Gomes Nícoli Göran Skog Peter Ekström Rosangela da Silveira Corrêa 《Journal of environmental radioactivity》2009
Atmospheric air samples were taken within 3 km from power plants encompassing five different distances and wind directions. Samples were taken between 2002 and 2005 aiming to evaluate the environmental 14C enrichment due to the operation of Brazilian nuclear power plants. The sampling system consisted of a pump connected to a trapping column filled with a 3 M NaOH solution. The trapped CO2 was analyzed for 14C by using a single stage accelerator mass spectrometry (SSAMS). 相似文献
64.
A Systematic Framework for the Design and Implementation of a Quality Management Practice: The Case of a Consulting Engineering Company
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Herlander Mata‐Lima Fernando Morgado‐Dias Marina Carrato Galuzzi da Silva Kelly Alcântara José António Almeida 《环境质量管理》2016,25(4):49-61
Company productivity and competitiveness in today's marketplace requires creative design, innovation, and the reduction of nonconformances, which require costly rework and can damage a firm's reputation with its customers and potential customers. Using the International Organisation of Standardization's (ISO) 9000 and 14000 series of standards, the authors of this article walk readers through the rigorous process of obtaining upper management buy‐in and sponsorship and engaging workers in a bottom‐up approach to establish the procedures necessary to perform world‐class engineering services. 相似文献
65.
Herlander Mata‐Lima Andreilcy Alvino‐Borba Karen Akamatsu Bruno Incau Jakelline Jard Andreza Borba da Silva Fernando Morgado‐Dias 《环境质量管理》2016,26(2):89-104
This article proposes an integrated procedure to assess sustainability indicators that organizations can use to satisfy international requirements for sustainability. The indicators are related to key aspects of organizations, and their development includes comparing them to the results and policies of various other organizations that are seeking to achieve sustainability. The methodology we used is based on a bibliographic review, and it is intended to:
- Diagnose the state of the art of organizational sustainability,
- Provide organizations with tools to perform benchmarking based on the results, and
- Provide processes to identify best sustainability practices.
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Maria J. Lima M. Enis Leblebici Madalena M. Dias José Carlos B. Lopes Cláudia G. Silva Adrián M. T. Silva Joaquim L. Faria 《Environmental science and pollution research international》2014,21(19):11116-11125
The degradation of ciprofloxacin was studied in aqueous solutions by using a continuous flow homogeneous photo-Fenton process under simulated solar light. The effect of different operating conditions on the degradation of ciprofloxacin was investigated by changing the hydrogen peroxide (0–2.50 mM) and iron(II) sulphate (0–10 mg Fe L?1) concentrations, as well as the pH (2.8–10), irradiance (0–750 W m?2) and residence time (0.13–3.4 min) of the process. As expected, the highest catalytic activity in steady state conditions was achieved at acidic pH (2.8), namely 85 % of ciprofloxacin conversion, when maintaining the other variables constant (i.e. 2.0 mg L?1 of iron(II), 2.50 mM of hydrogen peroxide, 1.8 min of residence time and 500 W m?2 of irradiance). Additionally, magnetite magnetic nanoparticles (ca. 20 nm of average particle size) were synthesized, characterized and tested as a possible catalyst for this reaction. In this case, the highest catalytic activity was achieved at natural pH, namely a 55 % average conversion of ciprofloxacin in 1.8 min of residence time and under 500 W m?2. Some of the photocatalytic activity was attributed to Fe2+ leaching from the magnetic nanoparticles to the solution. 相似文献
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Analysis of organophosphorus pesticides in whole milk by solid phase microextraction gas chromatography method 总被引:3,自引:0,他引:3
Solid phase microextraction (SPME) was used for the extraction of residual coumaphos and dichlorvos in whole milk. The residues were analyzed by capillary gas chromatography equipped with nitrogen phosphorus detector (GC-NPD). A manual SPME holder with a 100-microm polyacrylate fiber was used. The optimized conditions for extraction by SPME method were: sample agitation, absorption temperature of 30 degrees C, absorption time of 40 min, desorption time of 10 min, and sample volume was 16.0 mL in the vial. Under these conditions, the calibration graphs were linear in the range of 0.17 microgL-1 to 1.75 microgL-1 for coumaphos and 0.69 microgL-1 to 6.90 microgL-1 for dichlorvos. Precision was good with RSD values of 13% for coumaphos and 14% for dichlorvos. The detection limits (LOD) were 0.060 microgL-1 for dichlorvos and 0.052 for coumaphos. The quantification limits (LOQ) were 0.086 microgL-1 for dichlorvos and 0.066 microgL-1 for coumaphos. The results obtained in this study suggest that SPME is a suitable technique for residual pesticide analysis of milk. The data demonstrate that particular OP pesticides used in dairy farming in the region of Minas Gerais were found to contaminate cow whole milk, and the residues are not removed by treating the milk by boiling. 相似文献
70.