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431.
This paper presents a case study of land-use/land-cover (LULC) changes from 1975 to 2014 in the central highlands of Ethiopia and traces out its impact on socioeconomic conditions of the local community in the study area. We used four time series Landsat satellite images, that is, Landsat MSS (1975), Landsat Thematic Mapper (1986), Enhanced Thematic Mapper (2000), and Landsat 8 OLI scenes (2014), to investigate the changes in LULC. In addition, individual interviews with 51 randomly selected households, discussions with focus group and key informants, and field observations were also incorporated for the study. The image classification indicated four categories of LULC classes: Natural forest, eucalyptus plantations, cropland/settlements, and grasslands. Between 1975 and 2014, cropland/settlements and eucalyptus plantations considerably increased, whereas grassland cover drastically decreased. According to the results, the area under cropland/settlements and eucalyptus plantations increased by 62 and 335%, respectively, with 74% concomitant decrease in the area of grasslands in the same period. Survey results showed that deterioration of soil fertility (41.2%) followed by shortage of land (35.3%) is the major constraint for crop production for poor farmers in the study area. However, better-off farmers ranked deterioration of soil fertility (64.7%) followed by lack of credit (17.6%) as priority constraints for crop production. Interviews mainly focused on selected women group revealed that the expansion of eucalyptus in the area greatly curbed the burdens of collecting fuel woods from long distances in the past. The availability of too many religious holidays (on average 16 days/month) directly or indirectly contributes to the current seasonal food shortages of the community. Generally, our results show that the community in the study area is beset with a host of social, economic, and institutional challenges. As a result, majority of the farming households are destitute, unable to make a livelihood from their small plot of land and live in absolute poverty. Therefore, in light of these finding, it is imperative that timely interventions by government and other development stakeholders are needed to come to grips with problems of soil fertility, land-use change, and food insecurity in the study area.  相似文献   
432.
We proposed and tested a moderated mediation model that jointly examines affect‐based and cognition‐based trust as the mediators and prosocial motivation as the moderator in relationships between transformational leadership and followers’ helping behavior towards coworkers. Data were collected from 348 sales and servicing employees and their supervisors in four private retail companies and five private manufacturing companies located in Southeast China. The results showed that both affect‐based trust and cognition‐based trust mediated the relationship between transformational leadership and followers’ helping behavior towards coworkers. Furthermore, moderated mediation analyses showed that affect‐based trust mediated the relationship between transformational leadership and followers’ helping behavior towards coworkers only among employees with high prosocial motivation, whereas cognition‐based trust mediated this relationship among only those with low prosocial motivation. Implications for the theory and practice of leadership are then discussed. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
433.
Surface soil and sediment samples were collected from the surroundings of Lila stream, which passes through the obsolete pesticides dumping area Kalashah Kaku near Lahore city, to evaluate the residual levels of 19 organochlorine pesticides (OCPs), their distribution and potential sources. OCPs followed the order: ∑ DDT>∑ HCH>dicofol>endrin>heptachlor>dieldrin. Ratios of β to γ-HCH highlighted an old source of technical HCH in the study area, whereas the predominance of p, p′-DDT and p, p′-DDE indicated presence of technical DDT in surface soils. Factor analysis based on principal component analysis identified the origin of OCPs from industrial activities in Kalashah Kaku and waste dumping from Ittehad Chemical Industries via open drains into Lila stream. Greater levels of DDTs and HCHs above quality guideline pose potential exposure risk to biological organisms, safety of agricultural products and human health in the surrounding of Lila stream.  相似文献   
434.
Heavy metal concentrations (Pb, Cd, and Cu) in classroom indoor dust were measured. The health risk (non-carcinogenic) of these heavy metals in classroom indoor dust to children was assessed based on United States Environmental Protection Agency health risk model. Indoor classroom dust samples were collected from 21 locations including windows, fans, and floors at a primary school in Sri Serdang, Malaysia. Classroom dust samples were processed using aqua regia method and analyzed for Pb, Cd, and Cu concentrations. The highest average heavy metal concentrations were found in windows, followed by floor and fan. Pb concentrations ranged from 34.17 μg/g to 101.87 μg/g, Cd concentrations ranged from 1.73 μg/g to 7.5 μg/g, and Cu concentrations ranged from 20.27 μg/g to 82.13 μg/g. Ventilation and cleaning process were found as the possible factors that contributed to heavy metal concentration in window, floor, and fan. Moreover, the hazard index (HI) and hazard quotient (HQ) values for heavy metals Cd and Cu were less than one. By contrast, the HI and HQ values for Pb (maximum values) were more than one, indicating potential non-carcinogenic risk to children. Long-term persistence of leaded petrol, building materials, interior paint, school located near industrial areas and major roads, as well as vehicle emission are the factors attributed to the presence of heavy metals in classroom dust. Further research under a long-term monitoring plan and actual values in a health risk model is crucial before a final decision on heavy metal exposure and its relationship to young children health risks can be made. Nevertheless, the findings of this study provide crucial evidence to include indoor dust quality in school assessment because the environmental processes and impacts of surrounding school area have health risk implications on young children.  相似文献   
435.
Toxicity,degradation and analysis of the herbicide atrazine   总被引:3,自引:0,他引:3  
Excessive use of pesticides and herbicides is a major environmental and health concern worldwide. Atrazine, a synthetic triazine herbicide commonly used to control grassy and broadleaf weeds in crops, is a major pollutant of soil and water ecosystems. Atrazine modifies the growth, enzymatic processes and photosynthesis in plants. Atrazine exerts mutagenicity, genotoxicity, defective cell division, erroneous lipid synthesis and hormonal imbalance in aquatic fauna and nontarget animals. It has threatened the sustainability of agricultural soils due to detrimental effects on resident soil microbial communities. The detection of atrazine in soil and reservoir sites is usually made by IR spectroscopy, ELISA, HPLC, UPLC, LC–MS and GC–MS techniques. HPLC/LC–MS and GC–MS techniques are considered the most effective tools, having detection limits up to ppb levels in different matrices. Biodegradation of atrazine by microbial species is increasingly being recognized as an eco-friendly, economically feasible and sustainable bioremediation strategy. This review presents the toxicity, analytical techniques, abiotic degradation and microbial metabolism of atrazine.  相似文献   
436.
Prenatal and early-life exposure to lead (Pb) is hypothesized to have adverse effects on childhood health. The aim of this study was to evaluate the prenatal exposure to Pb and its adverse effects on mothers and their infants who are residents of industrial (exposed) and domestic areas (referents) in Karachi, Pakistan. The biological samples (scalp hair and blood) of mother–infants pairs were analyzed for Pb levels by atomic absorption spectrometry after microwave-assisted acid digestion method. The Pb levels in scalp hair and blood samples of exposed mothers were found in the range of 7.52–8.70 μg/g and 115–270 μg/L, respectively, which were significantly higher than those values obtained for referent mothers (p?<?0.001). The Pb levels in the blood (umbilical cord) and hair of neonates of exposed mother that were found in the range of 83–178 μg/L and 4.95–7.23 μg/g, respectively, were significantly higher than the obtained values of referent neonates (p?>?0.001). The correlation between maternal and cord blood of both groups was found in the range of 0.708–0.724 (p?<?0.01). It was observed that there were higher Pb burdens in exposed mothers and their infants as compared to referent mothers–neonates.  相似文献   
437.
Journal of Material Cycles and Waste Management - Currently, most countries are burdened with the high generation of plastic wastes and the proper disposal of plastic wastes is a major challenge....  相似文献   
438.
Environmental Science and Pollution Research - The livelihoods of poor people living in rural areas of Indus Basin Irrigation System (IBIS) of Pakistan depend largely on irrigated agriculture....  相似文献   
439.
Environmental Science and Pollution Research - Modeling three-dimensional contaminant transport released from arbitrary shape source geometries is useful in hydrological and environmental sciences....  相似文献   
440.
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