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591.
In 2007, a program was initiated to monitor air levels of volatile organic compounds (VOCs) and bioaerosols in the vicinity of a municipal solid waste incinerator (MSWI) (Tarragona, Catalonia, Spain). To investigate the temporal trends of chemical and microbiological pollutants, four 6-monthly campaigns were performed. Air samples were collected at different distances and directions from the facility, as well as in reference sites. In general terms, the concentrations of microbiological agents were very similar to those found in urban zones worldwide. The seasonal evaluation of the results showed higher levels of gram-negative bacteria in winter, contrasting with the increase of the airborne amount of total bacteria in summer. On the other hand, the concentrations of VOCs (mean range: 7.6-18.2 μgm−3) were typical of suburban zones. The current exposure to those compounds should not mean additional health risks for the population living nearby. 相似文献
592.
Organochlorine pesticides (OCPs) have been beneficial to man and environment but their inadvertent use has caused considerable harm to human health. Despite the proliferation of different types of pesticides, organochlorines such as HCH and DDT still account for two third of the total consumption in India because of their low cost and versatility in action again various pests. Since, Assam, a state in North-eastern part of India is an endemic area with perennial transmission where mosquito borne diseases are serious health problems; these pesticides are still being used in huge quantities in vector control as well as in agriculture. A total of 331 human blood samples were collected from district Nagaon and Dibrugarh of Assam to determine the residue levels of DDT and HCH in human blood. The concentrations of selected persistent organochlorine pollutants were measured with gas chromatography-electron capture detector. The results demonstrated that the mean levels of total DDT and HCH were 743 μg L(-1) and 627 μg L(-1) for district Nagaon while 417 μg L(-1) and 348 μg L(-1) for district Dibrugarh. The difference of total HCH and total DDT between these two districts was found to be highly significant (P<0.0001). Among DDT metabolites, the same trend was observed for both the districts as p,p-DDT was the principal component contributed 41% for Nagaon and 58% for Dibrugarh. In case of HCH residues, for Nagaon, β-HCH was the predominant contaminant comprised more than 34% while for Dibrugarh, it was α-HCH that was contributing 43% of total HCH concentration. 相似文献
593.
An overview of experimental results and dispersion modelling of nanoparticles in the wake of moving vehicles 总被引:1,自引:0,他引:1
Understanding the transformation of nanoparticles emitted from vehicles is essential for developing appropriate methods for treating fine scale particle dynamics in dispersion models. This article provides an overview of significant research work relevant to modelling the dispersion of pollutants, especially nanoparticles, in the wake of vehicles. Literature on vehicle wakes and nanoparticle dispersion is reviewed, taking into account field measurements, wind tunnel experiments and mathematical approaches.Field measurements and modelling studies highlighted the very short time scales associated with nanoparticle transformations in the first stages after the emission. These transformations strongly interact with the flow and turbulence fields immediately behind the vehicle, hence the need of characterising in detail the mixing processes in the vehicle wake. Very few studies have analysed this interaction and more research is needed to build a basis for model development. A possible approach is proposed and areas of further investigation identified. 相似文献
594.
Hettiarachchi VC Hettiaratchi PJ Mehrotra AK Kumar S 《Environmental pollution (Barking, Essex : 1987)》2011,159(6):1715-1720
Methane biofiltration (MBF) is a novel low-cost technique for reducing low volume point source emissions of methane (CH4). MBF uses a granular medium, such as soil or compost, to support the growth of methanotrophic bacteria responsible for converting CH4 to carbon dioxide (CO2) and water (H2O). A field research program was undertaken to evaluate the potential to treat low volume point source engineered CH4 emissions using an MBF at a natural gas monitoring station. A new comprehensive three-dimensional numerical model was developed incorporating advection-diffusive flow of gas, biological reactions and heat and moisture flow. The one-dimensional version of this model was used as a guiding tool for designing and operating the MBF. The long-term monitoring results of the field MBF are also presented. The field MBF operated with no control of precipitation, evaporation, and temperature, provided more than 80% of CH4 oxidation throughout spring, summer, and fall seasons. The numerical model was able to predict the CH4 oxidation behavior of the field MBF with high accuracy. The numerical model simulations are presented for estimating CH4 oxidation efficiencies under various operating conditions, including different filter bed depths and CH4 flux rates. The field observations as well as numerical model simulations indicated that the long-term performance of MBFs is strongly dependent on environmental factors, such as ambient temperature and precipitation. 相似文献
595.
Kumar V Nakada N Yamashita N Johnson AC Tanaka H 《Environmental pollution (Barking, Essex : 1987)》2011,159(10):2906-2912
A detailed study of the free and conjugated estrogen load discharged by the eight major sewage treatment plants into the Yodo River basin, Japan was carried out. Sampling campaigns were focused on the winter and autumn seasons from 2005 to 2008 and the free estrogens estrone(E1), 17β-estradiol(E2), estriol(E3), 17α-ethynylestradiol(EE2) as well as their conjugated (sulfate and glucuronide) forms. For both sewage effluent and river water E2 and E1 concentrations were greatest during the winter period (December-March). This coincides with the period of lowest rainfall and lowest temperatures in Japan. E1 was the dominant estrogenic component in effluent (means of 10-50 ng/L) followed by E2 (means of 0.5-3 ng/L). The estrogen sulfate conjugates were found intermittently in the 0.5-1.7 ng/L concentration range in the sewage effluents. The greatest estrogen exposure was found to be in the Katsura River tributary which exceeded 1 ng/L E2-equivalents during the winter period. 相似文献
596.
Stress-strain response of plastic waste mixed soil 总被引:1,自引:0,他引:1
Recycling plastic waste from water bottles has become one of the major challenges worldwide. The present study provides an approach for the use plastic waste as reinforcement material in soil. The experimental results in the form of stress-strain-pore water pressure response are presented. Based on experimental test results, it is observed that the strength of soil is improved and compressibility reduced significantly with addition of a small percentage of plastic waste to the soil. The use of the improvement in strength and compressibility response due to inclusion of plastic waste can be advantageously used in bearing capacity improvement and settlement reduction in the design of shallow foundations. 相似文献
597.
Post-closure care (PCC) activities at landfills include cap maintenance; water quality monitoring; maintenance and monitoring of the gas collection/control system, leachate collection system, groundwater monitoring wells, and surface water management system; and general site maintenance. The objective of this study was to develop an integrated data and knowledge based decision making tool for preliminary estimation of PCC needs at closed landfills. To develop the decision making tool, 11 categories of parameters were identified as critical areas which could affect future PCC needs. Each category was further analyzed by detailed questions which could be answered with limited data and knowledge about the site, its history, location, and site specific characteristics. Depending on the existing knowledge base, a score was assigned to each question (on a scale 1-10, as 1 being the best and 10 being the worst). Each category was also assigned a weight based on its relative importance on the site conditions and PCC needs. The overall landfill score was obtained from the total weighted sum attained. Based on the overall score, landfill conditions could be categorized as critical, acceptable, or good. Critical condition indicates that the landfill may be a threat to the human health and the environment and necessary steps should be taken. Acceptable condition indicates that the landfill is currently stable and the monitoring should be continued. Good condition indicates that the landfill is stable and the monitoring activities can be reduced in the future. The knowledge base algorithm was applied to two case study landfills for preliminary assessment of PCC performance. 相似文献
598.
Ocampo-Duque W Juraske R Kumar V Nadal M Domingo JL Schuhmacher M 《Environmental science and pollution research international》2012,19(4):983-999
Purpose
A conceptual model to assess water quality in river basins was developed here. The model was based on ecological risk assessment principles, and incorporated a novel ranking and scoring system, based on self-organizing maps, to account for the likely ecological hazards posed by the presence of chemical substances in freshwater. This approach was used to study the chemical pollution in the Ebro River basin (Spain), whose currently applied environmental indices must be revised in terms of scientific accuracy. 相似文献599.
Bhavya Balagurumurthy Thallada Bhaskar K. L. N. Shiva Kumar Hari Bhagwan Goyal Dilip Kumar Adhikari 《Journal of Material Cycles and Waste Management》2013,15(3):328-334
The necessity to move towards a sustainable economy is increasing day by day owing to various problems like climate change, increasing crude oil prices, etc. In this line, hydropyrolysis of Jatropha seed deoiled cake has been carried out at various pressures of hydrogen (1, 20, 40 and 52 bar) at 450 °C. With an increase in pressure under the experimental conditions of present study from 1 to 40 bar, the yield of bio-oil is found to have increased and beyond 40 bar the bio-oil yields have decreased. It has been observed that the liquid bio-oil yield is highest at 17 wt% at 40 bar. The FTIR spectrum of the bio-oil and char at 40 bar shows maximum functionality, indicating the clear opening of the macromolecular structure. The EDAX analysis of the hydropyrolysis char obtained at 40 bar pressure show a maximum of 85 wt% carbon and minimum of oxygen 13 wt%. 相似文献
600.
Bhavya Balagurumurthy Twinkle S. Oza Thallada Bhaskar Dilip Kumar Adhikari 《Journal of Material Cycles and Waste Management》2013,15(1):9-15
Considering the current issues of carbon control and the desire to become less dependent on imported oil, the utilization of renewable hydrocarbons for the reduction of CO2 emission and production of liquid synthetic fuels/chemicals has been proposed by researchers worldwide. Efforts to make chemicals/fuels from renewable resources have escalated over the past few years. Biomass-based renewable hydrocarbons are considered to be one of the sources with the highest potential to contribute to the energy needs of modern society for both developed and developing economies worldwide. Fast pyrolysis is becoming an important thermal route to convert biomass to liquid fuels; however, the raw bio-oils obtained have a number of negative properties such as high acidity, high water content, and variable viscosity over time. To overcome this problem and produce bio-oil of good quality, process of ‘hyropyrolysis’ has been developed. The scope for using pyrolysis under hydrogen pressure and also by process of hydropyrolysis followed by in situ hydroconversion of vapors to give oils with much lower oxygen contents has been reviewed. 相似文献