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171.
Trygve Hesthagen Bjørn Walseng Leif Roger Karlsen Roy M. Langåker 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):339-345
We studied the effects of liming on fish and crustaceans in a watershed which is in a region known to have one of the highest
diversity of aquatic biota in Norway. This watershed, Enningdal, is shared between Norway (1/3) and Sweden (2/3) and includes
61 lakes > 1.0 ha in Norway. Liming started on a large scale in the 1980s. Currently, a total of 26 of lakes (43%) are limed,
covering 93% of the total lake area. The mean value ± S.D. of pH and the concentration of inorganic labile Al in these lakes
is 6.62 ± 0.35 and 3 ± 4 μg l−1, respectively. Historical data of fish communities have been obtained from surveys, while test-fishing and sampling of crustaceans
were conducted in 24 lakes in recent years (2002–2004). The present study shows that crustaceans to a greater extent than
fish has responded to improved water quality after more than 20 years of liming. Of a total of 120 fish populations, 42 (35%)
have gone extinct. Only five of the lost fish populations (12%) have been re-established, all due to human re-introductions.
Physical barriers are considered to be the main factor preventing fish from invading limed lakes. In contrast, crustaceans
have been re-established in most limed lakes. This may be mainly due to their good spreading capacity. However, they might
also have survived in refuges within the watershed, or as resting-eggs in the sediment. 相似文献
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Guanabara Bay is a 384-km2 coastal bay with 70% of the population of the metropolitan area of Rio de Janeiro located within its drainage basin. The
water quality of the Bay is impacted by domestic and industrial runoff, of which only 15% has been adequately treated. However,
based on a 14-year monitoring program, the water quality for most of Guanabara Bay remains acceptable because of intense tidal
flushing, and we failed to find a worsening of conditions during the 14-year study. The inner shallow regions of the Bay,
the western and northwestern parts, receive most of the drainage from metropolitan Rio de Janeiro. It is here that the water
quality is alarmingly poor, characterized by hypertrophic conditions and occasional hypoxic events. Fecal coliform counts
in these inner reaches of the Bay are 4–100 times higher than the maximum acceptable count for recreational waters. Hypertrophic
conditions prevail in Guanabara Bay, which is characterized by low dissolved oxygen, high biochemical oxygen demand, peaks
in fecal coliform, and extremely high chlorophyll-a concentrations, which reflect high quantities of nutrients entering the system. These anthropogenic pressures are a threat
to planktonic and benthic communities and are reminiscent of San Francisco Bay 30 years ago. The Guanabara Bay water quality
could be returned to pre-1950 conditions, but it would require sufficient political will and economic investment to ensure
that at least 80–90% of the domestic and industrial sewage were treated adequately.
Electronic Publication 相似文献
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Cecilia H. Lalander Geoffrey B. Hill Björn Vinnerås 《Waste management (New York, N.Y.)》2013,33(11):2204-2210
On-site sanitation solutions have gained much interest in recent years. One such solution is the urine diverting vermicomposting toilet (UDVT). This study evaluated the hygienic quality of the composted material in six UDVTs in operation in France. Samples were taken from three sampling positions in each toilet, with increasing distance from the fresh material. The concentration of Salmonella spp., Enterococcus spp., thermotolarent coliforms and coliphages were analysed and plotted against a number of variables. The variables found to have the greatest impact was the pH (for Enterococcus spp. and thermotolarent coliforms (TTC)) and time since last maintenance (coliphages). The pH was found to correlate with the material maturity. The current practise of maintenance can cause recontamination of the stabilised material and increase the risk of regrowth of pathogenic microorganisms. A modification in the maintenance procedure, in which a fourth maturation point is introduced, would eliminate this risk. UDVTs were found to be a good on-site sanitation option as the maintenance requirement is small and the system effectively reduced odour and concentration of pathogen and indicator organisms in human waste while keeping the accumulation of material down to a minimum. If the vermicompost is to be used for crops consumed raw, an additional sanitisation step is recommended. 相似文献
177.
Lisa Leimar Price Astrid Björnsen Gurung 《Environment, Development and Sustainability》2006,8(4):507-517
The paper presents a methodology that guided several ethnoentomological research projects and goes on to examine and compare the results from two independent research locations in Asia. The first location is in the Philippines, a Green Revolution area that has been heavily impacted by extension messages and insecticide use. The second location is in Nepal which has a traditional subsistence orientation and has remained widely unaffected by agricultural modernization. The paper emphasizes the differences and similarities of the results from the two sites and discusses the role of the methodology and methods used in capturing ethnoentomological knowledge, particularly with regard to insect pests in rice. The results of both investigations share the importance of agronomic criteria among farmers in insect classification and sorting criteria, thus highlighting the relevance of functional criteria. Farmers at both research sites have difficulties in identifying the lifecycles of insects. We discuss the issues of tradition and change in farmer entomological knowledge and providing support to the knowledge base of farmers though programs like IPM-Farmer Field Schools as opposed to broad-based recommendations for crop pest management.Article type: MS-ENVI-SI ETHNOSCI MS04 Contribution to Environment, Development & Sustainability, special issue ‘Bridging the gap between natural resources and their human management for the future using ethnoscience’. 相似文献
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For remanufacturing to be successful, there is a need to gain information on future market needs of remanufactured products, and match this to information on the magnitude of return flows. One of the major issues impacting remanufacturing is in the difficulty of obtaining used products (cores) that are suitable for remanufacturing. The timing and quantity of product returns is dependent on the type of product. Factors such as the mean product lifetime, rate of technical innovation, and failure rate of components all influence the return rate of products from end-of-use and end-of-life. The balance between product returns and demand for remanufactured products is a function of many variables, where the rate of technological innovation and the expected life of a product are the major influencing characteristics. The main contribution of this paper is the support that is provided in different supply and demand situations. By using a product life-cycle perspective, the supply and demand situations can be foreseen, and support given regarding possible strategies in these situations. 相似文献