全文获取类型
收费全文 | 373篇 |
免费 | 9篇 |
国内免费 | 3篇 |
专业分类
安全科学 | 13篇 |
废物处理 | 12篇 |
环保管理 | 91篇 |
综合类 | 42篇 |
基础理论 | 93篇 |
环境理论 | 1篇 |
污染及防治 | 78篇 |
评价与监测 | 36篇 |
社会与环境 | 11篇 |
灾害及防治 | 8篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 7篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 7篇 |
2015年 | 8篇 |
2014年 | 15篇 |
2013年 | 20篇 |
2012年 | 15篇 |
2011年 | 28篇 |
2010年 | 15篇 |
2009年 | 17篇 |
2008年 | 18篇 |
2007年 | 22篇 |
2006年 | 16篇 |
2005年 | 15篇 |
2004年 | 18篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有385条查询结果,搜索用时 15 毫秒
81.
This paper explores the implications of work schedule flexibility for family life. Based on data from the 1977 Quality of Employment Survey, it demonstrates that flexibility of work schedules moderates the effects of nonstandard work schedules on family life. That is, nonstandard work schedules tend to have a less negative association with the quality of family life when accompanied by a high level of schedule flexibility. The paper further demonstrates that this tendency of flexibility to act as a buffer against the negative effects of nonstandard work schedules on family life is more pronounced among working women than working men. 相似文献
82.
Graham A. Tobin Thomas G. Newton 《Journal of the American Water Resources Association》1986,22(1):67-71
ABSTRACT: By integrating literature from flood hazard research and urban economics a theoretical structure is developed to explain changes in residential land values following flood events. The negative aspects of the flood hazard are shown to be capitalized in the value of the property. It is further suggested that land values (i.e., capitalization) will vary both spatially across the floodplain and temporally depending on the frequency, severity and spatial characteristics of the flood event. Previous work in this area has not addressed the capitalization process explicitly and has not specifically examined the ability of the land market to recover. This may account for the contradictory findings in the published literature. 相似文献
83.
/ Land use/land cover classifications for 1973 and 1991, derived from the interpretation of satellite imagery, are quantified on the basis of biophysical land units in a study area in southeastern Australia. Nutrient export potentials are estimated for each land unit based on their composition of land use/land cover classes. Spatial and temporal comparisons are made of the land units based on the calculated pollution hazard indicators to provide an insight into changes in the state of the environment and the regional significance of land use changes. For example, one ecosystem, unique to the study, showed a large increase in pollution hazard over the study period as a manifestation of an 11-fold rise in cleared area and an expansion of cropping activities. The benefits to environmental management in general are discussed.KEY WORDS: Land cover change; Nutrient export; Environmental condition; Pollution hazard; Agricultural pollution; Nonpoint source pollution; Diffuse pollution; Environmental degradation 相似文献
84.
Charles T. Garten Deanne J. Brice Hector F. Castro Robin L. Graham Melanie A. Mayes Jana R. Phillips Wilfred M. Post Christopher W. Schadt Stan D. Wullschleger Donald D. Tyler Phillip M. Jardine Julie D. Jastrow Roser Matamala R. Michael Miller Kelly K. Moran Timothy W. Vugteveen R. Cesar Izaurralde Allison M. Thomson Tristram O. West James E. Amonette Jeffrey L. Smith 《Agriculture, ecosystems & environment》2011,140(1-2):289-297
Switchgrass (Panicum virgatum) is a perennial, warm-season grass that has been identified as a potential biofuel feedstock over a large part of North America. We examined above- and belowground responses to nitrogen fertilization in “Alamo” switchgrass grown in West Tennessee, USA. The fertilizer study included a spring and fall sampling of 5-year old switchgrass grown under annual applications of 0, 67, and 202 kg N ha?1 (as ammonium nitrate). Fertilization changed switchgrass biomass allocation as indicated by root:shoot ratios. End-of-growing season root:shoot ratios (mean ± SE) declined significantly (P ≤ 0.05) at the highest fertilizer nitrogen treatment (2.16 ± 0.08, 2.02 ± 0.18, and 0.88 ± 0.14, respectively, at 0, 67, and 202 kg N ha?1). Fertilization also significantly increased above- and belowground nitrogen concentrations and decreased plant C:N ratios. Data are presented for coarse live roots, fine live roots, coarse dead roots, fine dead roots, and rhizomes. At the end of the growing season, there was more carbon and nitrogen stored in belowground biomass than aboveground biomass. Fertilization impacted switchgrass tissue chemistry and biomass allocation in ways that potentially impact soil carbon cycle processes and soil carbon storage. 相似文献
85.
Semi-volatile and particulate emissions from the combustion of alternative diesel fuels 总被引:8,自引:0,他引:8
Motor vehicle emissions are a major anthropogenic source of air pollution and contribute to the deterioration of urban air quality. In this paper, we report results of a laboratory investigation of particle formation from four different alternative diesel fuels, namely, compressed natural gas (CNG), dimethyl ether (DME), biodiesel, and diesel, under fuel-rich conditions in the temperature range of 800-1200 degrees C at pressures of approximately 24 atm. A single pulse shock tube was used to simulate compression ignition (CI) combustion conditions. Gaseous fuels (CNG and DME) were exposed premixed in air while liquid fuels (diesel and biodiesel) were injected using a high-pressure liquid injector. The results of surface analysis using a scanning electron microscope showed that the particles formed from combustion of all four of the above-mentioned fuels had a mean diameter less than 0.1 microm. From results of gravimetric analysis and fuel injection size it was found that under the test conditions described above the relative particulate yields from CNG, DME, biodiesel, and diesel were 0.30%. 0.026%, 0.52%, and 0.51%, respectively. Chemical analysis of particles showed that DME combustion particles had the highest soluble organic fraction (SOF) at 71%, followed by biodiesel (66%), CNG (38%) and diesel (20%). This illustrates that in case of both gaseous and liquid fuels, oxygenated fuels have a higher SOF than non-oxygenated fuels. 相似文献
86.
Optimising the preparation of activated carbon from digested sewage sludge and coconut husk. 总被引:18,自引:0,他引:18
Preparation of activated carbon from sewage sludge is a promising way to dispose of sewage sludge as well as to produce a low-cost adsorbent for pollutant removal. This research work aimed to optimise the condition for activated carbon preparation from anaerobically digested sewage sludge with the additive coconut husk. The sewage sludge sample was mixed with the additive coconut husk. The preparation condition variables investigated involved the concentration of the ZnCl2 solutions, heating temperature, dwell time and heating rate in pyrolysis and the mixing ratio of coconut husk to sewage sludge. Surface area, pore size distribution, aqueous phenol adsorption capacity and the production yield of the final products were determined and compared. Experimental results revealed that low concentrations of ZnCl2 solution tended to improve the microporosity of the final product. Heating temperature had a considerable impact on the surface area, pore size distribution and phenol adsorption capacity of the final products, whereas dwell time and heating rate performed comparatively insignificantly. The effect of increasing the mixing ratio of coconut husk to sewage sludge was principally to increase the microporosity of the final products. The activated carbon with the highest BET surface area was produced with the activation of 5 M ZnCl2 solution and, thereafter, pyrolysis at a heating temperature of 500 degrees C for 2 h with a heating rate of 10 degrees C/min. The mixing ratio of 1:4 in terms of coconut husk to sewage sludge based on their dried weights was found to be most cost effective. 相似文献
87.
F. A. Hockley C. A. M. E. Wilson N. Graham J. Cable 《Behavioral ecology and sociobiology》2014,68(9):1513-1520
Group living in fish can provide benefits of protection from predators and some parasites, more efficient foraging for food, increased mating opportunities and enhanced energetic benefit when swimming. For riverine species, shoaling behaviour can be influenced by various environmental stressors, yet little is known how flow rate might influence the shoaling of diseased fish shoals. In view of the increasingly unpredictable flow rates in streams and rivers, this study aimed to assess the combined effect of flow condition and parasitism on the shoaling behaviour of a model fish species. Shoal size, shoal cohesion and time spent shoaling of female guppies Poecilia reticulata were compared when infected with the directly transmitted ectoparasite Gyrodactylus turnbulli under flow and static conditions. Flow condition was an important factor in influencing shoaling behaviour of guppies with the fish forming larger shoals in the absence of flow. When a shoal member was infected with G. turnbulli, shoal cohesion was reduced, but the magnitude of this effect was dependent on flow condition. In both flow and static conditions, bigger fish formed larger shoals than smaller counterparts. Future changes to stream hydrology with more frequent flooding and drought events will affect the shoaling tendency of fish. During high-flow events, diseased fish may not be able to keep up with shoal mates and therefore have a higher risk of predation. Additionally, these findings may be important for aquaria and farmed species where an increase in flow rate may reduce aggregation in fish. 相似文献
88.
Paula Méndez-Fernandez Graham J. Pierce Paco Bustamante Tiphaine Chouvelon Marisa Ferreira Angel F. González Alfredo López Fiona L. Read M. Begoña Santos Jérôme Spitz José V. Vingada Florence Caurant 《Marine Biology》2013,160(11):2825-2840
This study aims to assess niche segregation among the five main toothed whales that frequent the NW Iberian Peninsula waters: the common dolphin, the harbour porpoise, the bottlenose dolphin, the striped dolphin and the long-finned pilot whale. We used cadmium (Cd) and stable isotope ratios (δ13C and δ15N) as ecological tracers to assess degree of segregation in diet/trophic level and in foraging habitat, over various time-scales. δ13C values highlighted different habitats, while Cd concentrations highlighted feeding differences between oceanic and neritic species. Moreover, δ15N values suggest different trophic levels of prey targeted within oceanic and neritic species. Hence, results revealed long-term ecological segregation among five toothed whales that coexist in the NWIP and demonstrated the ability of ecological tracers to discriminate ecological niches among closely related species. 相似文献
89.
90.
Graham Bird Mark G. Macklin Paul A. Brewer Sorin Zaharia Dan Balteanu Basarab Driga Mihaela Serban 《Environmental geochemistry and health》2009,31(6):741-758
Groundwater, accessed using wells and municipal springs, represents the major source of potable water for the human population
outside of major urban areas in northwestern Romania, a region with a long history of metal mining and metallurgy. The magnitude
and spatial distribution of metal contamination in private-supply groundwater was investigated in four mining-affected river
catchments in Maramureş and Satu Mare Counties through the collection of 144 groundwater samples. Bedrock geology, pH and
Eh were found to be important controls on the solubility of metals in groundwater. Peak metal concentrations were found to
occur in the Lapuş catchment, where metal levels exceed Dutch target and intervention values in up to 49% and 14% of samples,
respectively. A 700 m wide corridor in the Lapuş catchment on either side of the main river channel was identified in which
peak Cd (31 μg l−1), Cu (50 μg l−1), Pb (50 μg l−1) and Zn (3,000 μg l−1) concentrations were found to occur. Given the generally similar bedrock geologies, lower metal levels in other catchments
are believed to reflect differences in the magnitude of metal loading to the local environment from both metal mining and
other industrial and municipal sources. Sampling of groundwater in northwestern Romania has indicated areas of potential concern
for human health, where heavy metal concentrations exceed accepted environmental quality guidelines. The presence of elevated
metal levels in groundwater also has implications for the implementation of the EU Water Framework Directive (WFD) and achieving
‘good’ status for groundwater in this part of the Danube River Basin District (RBD). 相似文献