首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   269篇
  免费   0篇
  国内免费   19篇
安全科学   6篇
废物处理   25篇
环保管理   14篇
综合类   62篇
基础理论   45篇
环境理论   1篇
污染及防治   105篇
评价与监测   10篇
社会与环境   20篇
  2023年   3篇
  2022年   1篇
  2021年   2篇
  2020年   3篇
  2019年   2篇
  2018年   14篇
  2017年   4篇
  2016年   5篇
  2015年   7篇
  2014年   12篇
  2013年   34篇
  2012年   20篇
  2011年   20篇
  2010年   10篇
  2009年   22篇
  2008年   21篇
  2007年   29篇
  2006年   20篇
  2005年   16篇
  2004年   11篇
  2003年   5篇
  2002年   11篇
  2000年   2篇
  1999年   2篇
  1998年   3篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
  1988年   1篇
  1987年   1篇
  1983年   2篇
  1965年   1篇
  1963年   1篇
排序方式: 共有288条查询结果,搜索用时 15 毫秒
1.
The composting process of different organic wastes both in laboratory and on a large-scale was characterized using CIELAB color variables to evaluate compost stability for the better application in agriculture. The time courses of the CIELAB variables of composting materials were determined directly from the bottom of a glass petri dish filled with dried and ground samples using a Minolta Color Reader (CR-13) calibrated with clean empty petri dishes placed on a white tile. To compare the proposed method with conventional methods, the same materials were also evaluated using commonly used compost stability evaluation indices. Most of the CIELAB variables of a compost made from a mixture of green tea waste and rice bran reached a plateau after 84 days of composting and showed strong relationships with the commonly used compost stability evaluation indices. The time needed for CIELAB variables, especially the L*and b* values, to stabilize at large-scale composting plants of cattle litter, farmyard manure, kitchen garbage and bark compost, were more or less similar to the times of maturation evaluated by the respective compost producers. The CIELAB color variable offers a new, simple, rapid and inexpensive means of evaluating compost stability and its quality prior to agricultural use.  相似文献   
2.
Assessment of airborne organophosphorus pesticides in houses of young children (1-6 years old) and childcare facilities was conducted following pesticide applications in an agricultural community in Japan. Trichlorfon and fenitrothion, applied in two separate periods, were frequently detected from outdoor and indoor air. Dichlorvos, the primary degradation product of trichlorfon, was also detected after the application of trichlorfon. Both the outdoors and indoor concentration of applied pesticide were shown to increase with decreasing distance from the pesticide-applied farm. Indoor concentration of these pesticides significantly correlated with outdoor concentration (p=0.001 for trichlorfon and p=0.001 for fenitrothion), indicating infiltration of applied pesticide inside. Ratio of indoor to outdoor concentration (I/O ratio) of fenitrothion was higher for houses with windows open during the application than those with closed windows (median value: 0.74 vs. 0.16, p=0.003). However, a similar trend was not observed for trichlorfon as well as dichlorvos in the first period. Dichlorvos was found to have a higher I/O ratio than trichlorfon during the period, and clear correlation between indoor concentrations of dichlorvos and those of trichlorfon suggested increased decomposition of trichlorfon in the indoor environment. Daily inhalation exposure estimated by using the fixed measurement data and time-activity questionnaire ranged from 0 to 35 ng/kg/day for trichlorfon, from 0 to 26 ng/kg/day for dichlorvos, and from 0 to 44 ng/kg/day for fenitrothion. Median inhalation exposure from indoor air accounted for 74%, 86.3%, and 45% of the daily inhalation exposure, respectively. For kindergarteners or nursery school children, inhalation exposure at childcare facilities was comparable with or more than that at home, indicating that pollution level at childcare facilities had potential of high impact on children's exposure. Estimated daily inhalation exposures were inversely correlated to the proximity of their activity location to the pesticide-applied farm.  相似文献   
3.
This study focuses on analyses of greenhouse gas (GHG) emission reductions, from the perspective of interrelationships among time points and countries, in order to seek effective reductions. We assessed GHG emission reduction potentials and costs in 2020 and 2030 by country and sector, using a GHG emission reduction-assessment model of high resolution regarding region and technology, and of high consistency with intertemporal, interregional, and intersectoral relationships. Global GHG emission reduction potentials relative to baseline emissions in 2020 are 8.4, 14.7, and 18.9 GtCO2eq. at costs below 20, 50, and 100 $/tCO2eq., corresponding to +19, −2, and −7 %, respectively, relative to 2005. The emission reduction potential for 2030 is greater than that for 2020, mainly because many energy supply and energy-intensive technologies have long lifetimes and more of the current key facilities will be extant in 2020 than in 2030. The emission reduction potentials in 2030 are 12.6, 22.0, and 26.6 GtCO2eq. at costs below 20, 50, and 100 $/tCO2eq., corresponding to +19, −2, and −7 %, respectively, relative to 2005. The emission reduction potential for 2030 is greater than that for 2020, mainly because many energy supply and energy-intensive technologies have long lifetimes and more of the current key facilities will be extant in 2020 than in 2030. The emission reduction potentials in 2030 are 12.6, 22.0, and 26.6 GtCO2eq. at costs below 20, 50, and 100 /tCO2eq., corresponding to +33, +8, and −3 %, respectively, relative to 2005. Global emission reduction potentials at a cost below 50 $/tCO2eq. for nuclear power and carbon capture and storage are 2.3 and 2.2 GtCO2eq., respectively, relative to baseline emissions in 2030. Longer-term perspectives on GHG emission reductions toward 2030 will yield more cost-effective reduction scenarios for 2020 as well.  相似文献   
4.
IntroductionIncreasing public interests have been concerned onsafety foods and the environmental aspects recently,especially on the so-called organic foods , which are madefromcrops grown with organic fertilizers or compost but notchemical fertilizers .Pu…  相似文献   
5.
To explore neuro-endocrinal changes in the brain of European honeybee (Apis mellifera) queens before and after mating, we measured the amount of several biogenic amines, including dopamine and its metabolite in the brain of 6- and 12-day-old virgins and 12-day-old mated queens. Twelve-day-old mated queens showed significantly lower amounts of dopamine and its metabolite (N-acetyldopamine) than both 6- and 12-day-old virgin queens, whereas significant differences in the amounts of these amines were not detected between 6- and 12-day-old virgin queens. These results are explained by down-regulation of both synthesis and secretion of brain dopamine after mating. It is speculated that higher amounts of brain dopamine in virgin queens might be involved in activation of ovarian follicles arrested in previtellogenic stages, as well as regulation of their characteristic behaviors.  相似文献   
6.
Biofilm fermentation is a newly developed promising technique in fermentation technology. In this study no.3 and no.3S media have been used for the lipopeptide antibiotic iturin A production by Bacillus subtilis RB14. The main component of no.3 and no.3S media is Polypepton and Polypepton S, respectively. B. subtilis RB14 produces thick stable biofilm and high amount of iturin A in no.3S medium. Whereas, impaired biofilm formation and lower iturin A production was observed in no.3 medium. From the analytical information it was observed that the amounts of metal ions, such as K+, Ca2+ and Mn2+, cysteine and cellulose are lower in Polypepton compared to the Polypepton S. To investigate their effect on biofilm formation and iturin A production cysteine, cellulose, K+, Ca2+ and Mn2+ were added respectively into the no.3 medium at similar amount that Polypepton S contains. It was observed that individual addition of K+, Ca2+, cysteine and cellulose had no effect on biofilm formation, cellular growth induction or iturin A production. However, when Mn2+ was supplemented in no.3 medium, biofilm development was restored with an improved production of iturin A. Finally, combined addition of investigated substances into the no.3 medium resulted with highly folded, thick biofilm with high cellular growth and iturin A production compared to the original no.3 medium.  相似文献   
7.
We have successfully prepared a bead-type adsorbent from two materials with different adsorption characteristics. Heavy metals were removed by greatly swollen egg shell membrane-conjugated chitosan beads. The egg shell membrane accumulated and removed precious metal ions from a dilute aqueous solution with a high affinity in a short contact time. Experiments suggested that chitosan beads could take up gold ions with great capacity and selectivity by conjugation with egg shell membrane. Under certain conditions, the selective removal of gold and copper in a mixture of gold and copper ions by egg shell membrane-conjugated chitosan beads was 100% and 2%, respectively. Egg shell membrane-conjugated chitosan beads can be seen as a promising material to recover gold in wastewater from various industries, such as electroplating.  相似文献   
8.
Used lead–acid battery (ULAB) recycling has caused numerous health and environmental issues in developing countries. Surface soil pollution from ULAB recycling activities has been linked with elevated levels of lead in human blood. We measured surface soil lead in and surrounding the ULAB recycling village of Hung Yen in northern Vietnam in 2011, 2013, and 2014. The data were analyzed statistically and discussed with respect to distance from the contamination source, year of measurement, contamination pathway, and countermeasures against the contamination. Transportation routes from the smelter or collection site displayed the greatest concentration of surface soil lead (median 6400–10,000 mg/kg). Surface soil lead decreased significantly with distance along the road from the ULAB recycling site, although such a decrease was not observed for rice fields, agricultural roads, or garden soil. Re-suspension and adherence by traffic were identified as key pollution pathways. Distance from the source, covering of the surface of roads, construction of walls, and position relative to the source were shown to be the most effective factors in the reduction of surface soil lead pollution. Application of a combination of these measures should result in improvement in the health of residents.  相似文献   
9.
Inactivation of indigenous indicator micro-organisms such as faecal coliforms, coliphages, and faecal streptococci was investigated in a full-scale biogas plant that mainly digested cow manure. The biogas plant consisted principally of a feed reservoir, fermentation tank (37 degrees C), heat-inactivation process (70 degrees C), and five reservoirs for the heat-inactivated, digested manure that was used by a local livestock farmer as liquid fertilizer. Although all the indicators tended to exhibit stepwise decreases with each stage of treatment, coliphages were found to be more capable of surviving than faecal coliforms and faecal streptococci under mesophilic anaerobic conditions as well as high temperature conditions (heat-inactivation at 70 degrees C). Liquid fertilizer produced at the biogas plant had faecal coliform densities less than the stipulations of the US EPA 40 CFR 503 Class A limits. Heat-inactivation tests indicated that although coliphages exhibited more tolerance than other bacterial indicators between 37 and 70 degrees C, they were more sensitive to continuous temperature increase than faecal coliforms and faecal streptococci.  相似文献   
10.
End-of-life electrical and electronic equipment (EEE) has recently received attention as a secondary source of metals. This study examined characteristics of end-of-life EEE as secondary metal resources to consider efficient collection and metal recovery systems according to the specific metals and types of EEE. We constructed an analogy between natural resource development and metal recovery from end-of-life EEE and found that metal content and total annual amount of metal contained in each type of end-of-life EEE should be considered in secondary resource development, as well as the collectability of the end-of-life products. We then categorized 21 EEE types into five groups and discussed their potential as secondary metal resources. Refrigerators, washing machines, air conditioners, and CRT TVs were evaluated as the most important sources of common metals, and personal computers, mobile phones, and video games were evaluated as the most important sources of precious metals. Several types of small digital equipment were also identified as important sources of precious metals; however, mid-size information and communication technology (ICT) equipment (e.g., printers and fax machines) and audio/video equipment were shown to be more important as a source of a variety of less common metals. The physical collectability of each type of EEE was roughly characterized by unit size and number of end-of-life products generated annually. Current collection systems in Japan were examined and potentially appropriate collection methods were suggested for equipment types that currently have no specific collection systems in Japan, particularly for video games, notebook computers, and mid-size ICT and audio/video equipment.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号