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41.
Few ecotoxicological studies have used life table analysis to evaluate the toxicity of pesticides on beneficial organisms. This study is the first report of the effect of the herbicide glyphosate on a predator insect, Chrysoperla externa, using a demographic approach. This predator is associated to soybean pests and has a potential role as a biological control agent in the Neotropical Region. The objective of this work was to evaluate the side-effects of glyphosate on the development, fertility and demography of C. externa, treated orally by ingestion of glyphosate-dipped eggs of Sitotroga cerealella in laboratory conditions. The data were analyzed using the age-stage, two-sex life table. Development from third larval instar to pupae and adult longevity were shorter in glyphosate-treatment than in the control. Adult pre-reproductive period was longer in glyphosate-treatment than in the control. Fecundity and fertility were deeply reduced, as well, being fertility greater affected. A high important reduction was registered in all population parameters. Most eggs from glyphosate-treated cohort looked abnormal, smaller than control, dehydrated and became black 2 d after oviposition. In addition, adults developed tumours in the abdomen region at 20 d after emergence, being the effect more drastic in females than males. It is beyond the scope of our study to speculate on the effects of this herbicide on C. externa field populations. However, it seems likely that populations under continuous use of glyphosate would be exposed at greater detrimental effects in the long term.  相似文献   
42.
Journal of Polymers and the Environment - This study was developed a novel nanostructured membrane by electrospinning process, from polyacrylonitrile (PAN) modify by hydroxypropyl methylcellulose...  相似文献   
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44.
Farmers in rural Africa use a number of adaptive strategies to cope with observed climatic changes and their impacts on agriculture. Most studies on adaptive capacity focus on socio-economic parameters (such as poverty or education), and few provide detailed analysis on the role played by different institutions at local level, and the effects of how these institutions are perceived on farmers’ adaptation. Semi-structured interviews were conducted among 46 households from seven villages in southern Benin (West Africa), and among representatives of several institutions at the local level. Half the participants were involved in Non Governmental Organizations (NGOs) development projects and half were independent farmers. Results indicate that independent farmers mostly use non-agricultural coping strategies (loans, work in town) while project farmers mainly use agricultural adaptive strategies (improved seed varieties). Lack of adaptive capacity of independent farmers is linked to weak State institutions at the local level. Due to their lack of efficiency and high corruption rates, local State representatives are mistrusted. NGOs are trusted and seek for help, even by independent farmers. Even if NGOs do not have climate change adaptation in their agendas, they promote activities, which help reduce farmers’ vulnerability. Although our results are limited to south-western Benin, they question the way adaptation is promoted today, for instance through the United Nations Framework Convention for Climate Change (through the National Adaptation Programmes of Action).  相似文献   
45.
To estimate the human health risk of inhaled diesel particles, it is necessary to know their deposition and retention in the respiratory tract and the rate of dissociation of mutagenic compounds associated with the particles. The deposition of a chain aggregate aerosol of 67Ga2O3 with size and shape characteristics similar to diesel exhaust particles has been evaluated using Beagle dogs. Approximately one-third of the inhaled activity is deposited in the respiratory tract with most of the particles deposited in the lung. The mutagenic activity present in dichloromethane, dog serum, dog lung lavage fluid, saline, dipalmitoyl lecithin (DPL) and albumin following incubation of these fluids with diesel exhaust particles was determined in the Ames Salmonella system. As observed by other investigators, large quantities of mutagenic activity were removed by dichloromethane. A very small amount of mutagenic activity was removed by the serum and lavage fluid over a 3-day incubation period. No activity was detected following elution with the other solvents. The finding that minimal mutagenic activity could be demonstrated in the biological media following incubation with diesel exhaust particles may be due to a lack of removal of mutagens from the particles or an inactivation of removed mutagens by protein binding or other processes.  相似文献   
46.
The significance of exchange sites on organic matter in the retention of radiocaesium in highly organic soils remains unclear. To quantify this retention, we measured the binding of 134Cs to a humic acid isolated from a British upland peat soil, under a range of chemical conditions. We interpreted our results using Humic Ion Binding Model V, a model of humic substance chemistry which simulates ion exchange by non-specific accumulation of cations adjacent to the humic molecules. Model V could simulate the humic acid-solution partitioning of Cs under all the solution conditions used. The model was used to estimate the contribution of organic matter to Cs sorption by the whole soil composite. An estimate of Cs sorption by illite frayed edge sites was also made. These simulations show that organic matter may play only a minor role in binding Cs. even in highly organic soils.  相似文献   
47.
With the ending of the Cold War, the Department of Energy (DOE) is evaluating mission, future land use and stewardship of departmental facilities. This paper compares the environmental concerns and future use preferences of 351 people interviewed at Lewiston, Idaho, about the Hanford Site and Idaho National Engineering and Environmental Laboratory (INEEL), two of DOE's largest sites. Although most subjects lived closer to Hanford than INEEL, most resided in the same state as INEEL. Therefore their economic interests might be more closely allied with INEEL, while their health concerns might be more related to Hanford. Few lived close enough to either site to be directly affected economically. We test the null hypotheses that there are no differences in environmental concerns and future land-use preferences as a function of DOE site, sex, age and education. When asked to list their major concerns about the sites, more people listed human health and safety, and environmental concerns about Hanford compared to INEEL. When asked to list their preferred future land uses, 49% of subjects did not have any for INEEL, whereas only 35% did not know for Hanford. The highest preferred land uses for both sites were as a National Environmental Research Park (NERP), and for camping, hunting, hiking, and fishing. Except for returning the land to the tribes and increased nuclear storage, subjects rated all future uses as more preferred at INEEL than Hanford. Taken together, these data suggest that the people interviewed know more about Hanford, are more concerned about Hanford, rate recreational uses and NERP as their highest preferred land use, and feel that INEEL is more suited for most land uses than Handford. Overall rankings for future land uses were remarkably similar between the sites, indicating that for these stakeholders, DOE lands should be preserved for research and recreation. These preferences should be taken into account when planning for long-term stewardship at these two DOE sites.  相似文献   
48.
Environmental psychology is a new discipline in Venezuela, which is developing together with, and in response to, the conditioning social and political background of the country. A review of this background and an analysis of the present status of scientific research in the field is presented. The most frequent, and the most neglected, research fields are considered in addition to the principal direction found presently in university education, which will help to determine the formation of future professionals. It is concluded that research in the field is increasing in terms of frequency and variety of themes despite its brief history in the country.  相似文献   
49.
Utilization of secondary materials in civil engineering applications (e.g. as substitutes for natural aggregates or binder constituents) requires assessment of the physical and environment properties of the product. Environmental assessment often necessitates evaluation of the potential for constituent release through leaching. Currently most leaching models used to estimate long-term field performance assume that the species of concern is uniformly dispersed in a homogeneous porous material. However, waste materials are often comprised of distinct components such as coarse or fine aggregates in a cement concrete or waste encapsulated in a stabilized matrix. The specific objectives of the research presented here were to (1) develop a one-dimensional, multi-regime transport model (i.e. MRT model) to describe the release of species from heterogeneous porous materials and, (2) evaluate simple limit cases using the model for species when release is not dependent on pH. Two different idealized model systems were considered: (1) a porous material contaminated with the species of interest and containing inert aggregates and, (2) a porous material containing the contaminant of interest only in the aggregates. The effect of three factors on constituent release were examined: (1) volume fraction of material occupied by the aggregates compared to a homogeneous porous material, (2) aggregate size and, (3) differences in mass transfer rates between the binder and the aggregates. Simulation results confirmed that assuming homogeneous materials to evaluate the release of contaminants from porous waste materials may result in erroneous long-term field performance assessment.  相似文献   
50.
Foreign-owned industry in the form of assembly plants, termed maquiladora, has become very important in Mexico to the extent that it represents the second largest source of foreign exchange and is a valuable source for employment and regional development. The economic prosperity gained from the rapid growth of the maquiladora industry has been accompanied by increased environmental and human health risks associated with generation of hazardous waste. Diversification of industry has resulted in the predomination of those sectors that likely use hazardous substances. The Mexicali-Calexico border region was selected to demonstrate the potential for environmental and health risks associated with the generation of hazardous waste. Estimates for the generation of hazardous waste were obtained from 34 maquiladora plants in Mexicali, represented by the electronic and electrical equipment and parts, mechanical and transportation equipment, and toys and sporting equipment sectors. Repeated detection of volatile organic compounds in the New River at the US-Mexico border suggests that hazardous waste from the printed circuit board industry in Mexicali is not being disposed of in a proper manner. Potential adverse health effects, such as carcinogenic and mutagenic responses associated with the detected volatiles, are discussed. US and Mexico national legislation and the Binational Environmental Agreement were examined for their adequacy to ensure proper management of hazardous waste generated by the maquiladora industry. Environmental policy options are presented that focus on: (1) increased environmental accountability of US parent companies for their maquiladora assembly plants in Mexico; and (2) more integration between US Customs and border states with the US Environmental Protection Agency to improve the binational management of hazardous waste generated by the maquiladora industry.  相似文献   
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