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   203篇
  免费   60篇
  国内免费   49篇
安全科学   17篇
废物处理   1篇
环保管理   4篇
综合类   163篇
基础理论   9篇
污染及防治   81篇
评价与监测   12篇
社会与环境   22篇
灾害及防治   3篇
  2024年   4篇
  2023年   12篇
  2022年   28篇
  2021年   16篇
  2020年   20篇
  2019年   16篇
  2018年   9篇
  2017年   7篇
  2016年   7篇
  2015年   25篇
  2014年   24篇
  2013年   17篇
  2012年   25篇
  2011年   7篇
  2010年   18篇
  2009年   22篇
  2008年   3篇
  2007年   13篇
  2006年   5篇
  2005年   4篇
  2004年   1篇
  2002年   3篇
  2001年   7篇
  2000年   1篇
  1999年   6篇
  1997年   1篇
  1993年   1篇
  1990年   3篇
  1988年   2篇
  1987年   2篇
  1986年   3篇
排序方式: 共有312条查询结果,搜索用时 15 毫秒
261.
基于稀释通道原理自设固定源PM2.5稀释采集系统,应用该系统对陕西省关中地区某燃煤电厂湿式电除尘器(WESP)进出口烟气中的PM2.5、PM10和颗粒物开展了现场实测,并在实验室对采集样品进行了化学源组分分析。结果表明:WESP对PM2.5、PM10和颗粒物的脱除效率分别为67.85%、43.57%、40.88%;WESP前后质量浓度峰值均出现在积聚模态,但由双峰(1.764μm、0.649μm)变成单峰(1.764μm),峰值移至大粒径段,数浓度峰值出现在爱根核模态和积聚模态,但由多峰(0.017μm、0.129μm、0.384μm、1.764μm)变成双峰(0.017μm、0.073μm),峰值移至小粒径段;经WESP,PM2.5积聚模态大多粒径段颗粒物的质量浓度与数浓度均在下降,爱根核模态大多粒径段颗粒物的质量浓度与数浓度均在上升,无论是WESP前或后,PM2.5的主要质量浓度均集中在大粒径段、主要数浓度均集中在小粒径段;WESP对PM2.5中大粒径段颗粒物的去除效果要优于小粒径段颗粒物;WESP对PM2.5中全部已检出离子和大部分主要无机元素均具有去除作用,占离子总质量比重最高的SO42-和占元素总质量比重第5位的Mg去除率均最高(64.75%,接近100%);经WESP处理后,各检出离子的质量浓度大小排序未受任何影响(由大到小为SO4^2-、Na^+、Ca^2+、Cl^-、NO3^-、F^-、Mg^2+、NO2^-、NH4^+、K^+)。  相似文献   
262.
石油类污染物在陇东黄土塬区土壤中迁移的模拟试验研究   总被引:4,自引:1,他引:3  
采用一种新的土柱淋滤方法,在不同淋滤量、污染强度和柱长条件下模拟了陇东黄土塬区自然降水对石油污染物在土壤中纵向迁移的影响.结果表明,石油类污染物迁移的深度受污染强度、淋滤量、土层深度等因素的限制.污染物在土柱中峰值出现的深度均随污染强度、淋滤量和土层深度的增加呈增加的趋势,在0~10 cm的范围内,污染物均大量存在,且石油类污染物在土壤中的纵向迁移规律与污染强度、淋滤量、柱长等众多因素有关,即淋滤量越大污染物越容易发生迁移,污染强度越高迁移深度越大,土层越深迁移越容易实现.  相似文献   
263.
基于熵权物元可拓模型的城市大气质量评价   总被引:2,自引:0,他引:2  
本文分析城市大气环境的多耦合性与复杂动态性,识别城市环境质量中评价主体及环境要素的不确定性;确定城市大气污染评价因子及其评价等级的界定;实现可拓论经典集合中"属于"和"不属于"集合的定性描述扩展到精准定量描述,并将可拓工程方法与聚类分析相结合,依据大气质量等级标准和大气质量影响因子构造经典域物元和节域物元;实现关联函数逻辑域由(0,1)到(-∞,+∞)的扩展;并采用层次分析法(AHP)确定特征加权,建立变权可拓论的大气质量评价模型。新模型不仅可以体现大气质量整体等级水平,而且通过质量与等级的关联度可以辨识影响大气质量的主次要污染因子。以阜新市2010年大气环境质量为应用评价对象,将应用评价结果与上海大气质量指数法、模糊综合评判法的结果比较,给出新模型在大气质量评价应用中的适用性。  相似文献   
264.
本文分析了我国节能减排的困境与压力,研究提出了推动中国制造到中国设计的转变,实施名牌战略,开征碳转移税,完善指标体系,端正政绩观,全民总动员等节能减排措施。  相似文献   
265.
Introduction: Compared to other types of occupational training, safety training suffers from several unique challenges that potentially impair the engagement of learners and their subsequent application or “transfer” of knowledge and skills upon returning to the job. However, existing research on safety training tends to focus on specific factors in isolation, such as design features and social support. The aim of this research is to develop an overarching theoretical framework that integrates factors contributing to training engagement and transfer. Method: We conducted a comprehensive qualitative review of safety training research that was published between 2010 and 2020. We searched Web of Science, Scopus, and Google Scholar, yielding 147 articles, and 38 were included. We content analyzed article summaries to arrive at core themes and combined them with contemporary models of general occupational training to develop a rich model of safety training engagement and transfer. Results: We propose that training engagement is a combination of pre-training factors such as individual, organizational, and contextual factors, that interact with design and delivery factors. Safety training engagement is conceptualized as a three-component psychological state: affective, cognitive, and behavioral. Organizations should prioritize pre-training readiness modules to address existing attitudes and beliefs, optimize the safety training transfer climate, and critically reflect on their strategy to design and deliver safety training so that engagement is maximized. Conclusions: There are practical factors that organizations can use before training (e.g., tailoring training to employees’ characteristics), during training (e.g., ensuring trainer credibility and use of adult learning principles), and after training (e.g., integrating learned concepts into systems). Practical Applications: For safety training to ‘stick,’ workers should be affectively, cognitively, and behaviorally engaged in learning, which will result in new knowledge and skills, improvements in attitudes, and new safety behaviors in the workplace. To enable engagement, practitioners must apply adult learning principles, make the training relevant, and tailor the training to the job and individual needs. After training, ensure concepts are embedded and aligned with existing systems and routines to promote transfer.  相似文献   
266.
利用1963—2012年湖南省常德市逐日气温观测资料,运用线性拟合、主成分分析、Mann-Kendall突变检验和Morlet复数小波等方法对WMO发布的10种极端气温指数进行了计算和分析。结果表明常德地区近50年来,极端最高气温、极端最低气温都呈上升趋势,冰日、霜日、冷夜、冷日数量呈下降趋势,夏日、热夜、暖夜、暖日数量呈上升趋势。除冰日天数未出现突变外,各极端气温指标的突变基本发生在1980年代到1990年代末。极端最高气温、极端最低气温、夏日、热夜、霜目、暖夜、冷日、冷夜、暖日都存在27 a左右的周期,冰日存在29 a左右的周期。总体来说,近50年来,常德地区极端天气热指数呈上升趋势,极端天气冷指数呈下降趋势,发生极端天气现象的可能性增加。由此可能造成夏季高温干旱和暖冬等灾害,需要及时采取预防措施,防止高温干旱和暖冬等情况对工农业生产和居民生活带来负面影响。  相似文献   
267.
Eighty road dust-fall (DF) monitoring sites and 14 background monitoring sites were established in the Beijing metropolitan area, and monitoring was conducted from January 2006 to December 2008. The dust-fall attributable to roads (ΔDF) showed a clear decline from 2006 to 2008. Dust-fall levels decreased across different road types from freeway > major arterial roads > minor arterial roads > collector roads > background sites. The ΔDF showed declines of 65%, 55%, 65% and 84% respectively for freeways, major arterial, minor arterial and collector roads from August 2007 to August 2008, and declines of 77%, 76%, 82% and 82% between August 2006 and August 2008. The ΔDF declined by 80%, 79%, 82% and 69% for freeways, major arterial, minor arterial and collector roads respectively between September 2007 and September 2008, and declined by 84%, 88%, 80% and 81% between September 2006 and September 2008.Eighty samples were collected in August 2007 and August 2008 and analyzed for silt loading. PM10 emission factors and emission strengths were calculated using the AP-42 model. The silt loading reduced by 77%, 35%, 61%, 59% and 75% for freeways, major arterial, minor arterial, collector and local roads respectively. The PM10 emission factors were reduced by 57%, 15%, 36%, 51% and 61% and the PM10 emission strength declined by 70%, 40%, 55%, 65% and 72% for freeways, major arterial, minor arterial, collector and local roads respectively between August 2007 and August 2008. The decline is consistent with the reduction in road dust-fall.  相似文献   
268.
为探讨西安冬季不同大气污染状况(污染天和清洁天)大气细粒子(PM2.5)及其一次棕碳(BrCpri)和二次棕碳(BrCsec)的光学特征及辐射效应,开展了高分辨率多波段光学参数观测,获得PM2.5多波段光学吸收系数(babs),通过进一步数据分析得到BrCpri和BrCsec的光谱依赖指数(AAE)及其相对黑碳(BC)的辐射强迫.结果显示,污染天时段370nm光学吸收(babs(370))和880nm光学吸收(babs(880))均值分别为(733±311) Mm-1和(185±80) Mm-1,分别高出清洁天约5.9倍和6.2倍.清洁天PM2.5的AAE1.08~2.09,变化幅度大于污染天(1.28~1.79).清洁天棕碳光学吸收(babs(BrC))在370nm波长对总吸收占比高于污染天,均超过30%.一次棕碳光学吸收(babs(BrCpri))在清洁天和污染天均对babs(BrC)呈现高贡献,占比范围分别为76%~86%和82%~91%,说明一次排放仍然是造成西安冬季污染的重要原因.清洁天BrC、BrCpri和BrCsec的AAE均值分别为4.42、4.31和4.78,均高于污染天,说明清洁天粒子等效直径相对较小,老化程度较高导致BrC的高光谱依赖性.babs(BrCsec)日间变化表明污染天凌晨高湿条件下的液相反应可能是BrCsec形成的主要机制,比清洁天更为强烈,而污染天日间BrCsec受光漂白的影响较大.最后估算了BrCpri和BrCsec的辐射强迫效应,在紫外波段(300~400nm),污染天BrCpri和BrCsec相对BC的辐射强迫分别为62%和16%,而清洁天分别为59%和23%,表明BrCpri和BrCsec在西安冬季的辐射强迫效应不容忽视.  相似文献   
269.
Thirty six element signatures were compared in historical Parmelia sulcata samples from the Natural History Museum herbarium collected over the period 1797–1967 with those recorded in the same species and tree bark sampled in 2000 from Burnham Beeches, lying 40 km west of London. Nineteen elements reached highest concentrations in herbarium samples, consistent with a pollution legacy and dust contamination in the herbarium. Healthy Parmelia sampled east and down-wind of London at a farm during peak SO2 emissions in 1967 contained highest V, Ni, Zn, Cd, Se, Ge contents, supporting derivation from fuel combustion; the same sample was previously determined as having a low δ34S and high S and N contents. Lowest V, Co, Ni, Cu, Zn, Sn, Ba, Pb, Mo, Sb, Li, B, Cs, U, Th, Ga contents were recorded in a sample with a high δ34S and low S content collected in 1887 from a remote region from Ross-shire, Scotland. Se and Cd enrichment, never-the-less suggest a transboundary pollution influence. Lichen Pb concentrations from Burnham Beeches were amongst the lowest recorded in spite of lichens being collected close to roads. Herbarium samples help interpret changes in element deposition where few data exist, in spite of dust contamination.  相似文献   
270.
东北地区臭氧浓度空间格局演变规律及影响因素   总被引:2,自引:0,他引:2  
采用重心模型、空间自相关分析、地理探测器,研究了2016年东北地区O3浓度的空间分布格局及演变规律,揭示了气象因素和前体物对东北地区O3浓度空间分布格局及演变的影响.结果表明:东北地区O3-8 h-P90分布整体呈南高北低的态势,O3浓度的高值区及超标天数比例较高的地区都集中分布在环渤海地区的沿海城市;气温是影响O3年均浓度空间格局演变的主导因素,随着气温的变化,O3年均浓度空间分布格局呈现空间分异不明显-南高北低-空间分异不明显的演变特征;前体物是核心城市形成局部O3污染的主要原因,其影响力的大小受温度的影响,温度越高,光化学反应越强,前体物的正向影响力越大,温度越低,光化学反应越弱,化学性质活跃的前体物对O3可能起消耗作用.  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