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   261篇
  免费   50篇
  国内免费   42篇
安全科学   116篇
废物处理   8篇
环保管理   49篇
综合类   127篇
基础理论   13篇
污染及防治   12篇
评价与监测   20篇
社会与环境   7篇
灾害及防治   1篇
  2024年   4篇
  2023年   9篇
  2022年   12篇
  2021年   28篇
  2020年   26篇
  2019年   13篇
  2018年   10篇
  2017年   16篇
  2016年   15篇
  2015年   14篇
  2014年   18篇
  2013年   25篇
  2012年   23篇
  2011年   21篇
  2010年   16篇
  2009年   19篇
  2008年   15篇
  2007年   7篇
  2006年   12篇
  2005年   5篇
  2004年   5篇
  2003年   6篇
  2002年   10篇
  2001年   3篇
  2000年   2篇
  1999年   6篇
  1998年   1篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1994年   1篇
  1990年   1篇
  1989年   1篇
  1987年   1篇
  1978年   3篇
排序方式: 共有353条查询结果,搜索用时 31 毫秒
161.
以杭州市为研究区域,建立2010年机动车NOx排放清单,预测杭州市“十二五”期间新增机动车NOx排放量,并设定了“现行管理”、“改善方案”和“强化方案”3个机动车管理情景,对NOx的减排潜力进行分析.结果表明,2010年杭州市主城区NOx排放量为4.43万t,其中重型货车所占比例最大,为34.1%. “十二五”杭州市机动车将增加22万辆,新增NOx排放0.197万t.执行“改善方案”—机动车淘汰工程和油品替代工程,可减少NOx排放0.746万t,削减率为16.84%.增加混合动力公交车和新能源汽车的市场占有率可以提高NOx的减排潜力.  相似文献   
162.
基于布朗运动的自由飞行下碰撞风险研究   总被引:1,自引:0,他引:1  
自由飞行是解决空域拥挤的有效方式,为保证飞行安全,对自由飞行下的碰撞风险进行研究。首先,假设自由飞行下飞机的定位误差服从正态分布,在平面直角坐标系内,建立2架飞机水平投影面和垂直投影面的随机运动学模型;其次,当2架飞机在2个投影面上的相对运动距离同时小于最小安全间隔时认为碰撞发生,据此建立飞行碰撞风险模型,并利用欧拉(Euler)方法求解;最后,通过Matlab对一算例进行计算,得出碰撞风险概率。将计算结果与实际安全目标等级对比,验证该模型的合理性。  相似文献   
163.
为改善当前冲出跑道事故在风险辨识环节上存在的不足,提出运用寻因分析(WBA)法,对冲出跑道事故存在的风险进行更加严格、准确的辨识。首先简要介绍WBA方法的内容,然后运用WBA方法对具体事故进行危险源辨识,最后根据辨识出的危险源构建WBA结构图并进行分析。分析结果显示:实例事故的危险源共有14项,分别属于人、机、环,管4个方面。在此基础上,利用模糊层次分析法(FAHP)对辨识出的危险源进行权重排序,得出机组人员处置失误、飞行机组技术欠缺、天气原因、跑道表面积水、机组训练问题等5个最主要因素,并针对这5个因素提出改进对策。  相似文献   
164.
李义鹏    李亮亮    刘全桢    高鑫    孙立富   《中国安全生产科学技术》2017,13(12):157-161
为研究乙醇汽油使用过程中存在的静电风险及带电变化规律,基于自主研发的油品电荷密度表,试验研究了乙醇含量对管输汽油静电带电规律的影响,获得乙醇体积含量0~5%的管输油品静电数据;对油库内乙醇汽油装车作业及加油站加油作业乙醇汽油静电起电特性进行了试验研究。研究结果表明:随着乙醇含量的增加,油品静电呈现先增大后减小的趋势;乙醇体积含量在0.5%~1%时,油品静电起电量最高可达到-77.2 μC/m3,为此需注意乙醇汽油调配过程中可能存在的静电风险;高电导率的车用乙醇汽油在加油作业时,油品静电起电量较低。  相似文献   
165.
本研究分别利用2019年、2020年第一季度河北省国省道交通调查站监测数据,计算了两年国省道机动车逐日交通量及大气污染物排放量,分析了新冠肺炎疫情期间国省道机动车大气污染物排放的变化情况.与2019年相比,2020年第一季度河北省国省道交通量同比下降38.1%,单位公里CO、VOCs、NOx、PM2.5、PM10排放强度分别同比下降31.3%、32.7%、19.1%、20.2%、20.0%.从不同公路类型来看,2020年第一季度,普通公路交通量持续下降,国家高速和省级高速交通量在3月出现回升,分别同比增长5.6%、37.2%,且货车增速高于客车.2020年春运期间,客车、货车总交通量分别为去年同期的44.2%、51.0%,国省道CO、VOCs、NOx、PM2.5、PM10的排放强度分别是去年同期的51.4%、50.6%、52.6%、52.3%、52.3%.从2月14日开始,客车、货车交通量开始逐步回升,到3月底,国省道总交通量恢复到了去年同期的46.6%,其中,客车是去年同期的34.5%,货车是70.3%.  相似文献   
166.
Environmental effects of soil property changes with off-road vehicle use   总被引:1,自引:0,他引:1  
The effects of off-road vehicles (ORVs) on the physical and chemical properties of 6 soil series were measured at Hollister Hills State Vehicular Recreation Area in central California. Accelerated soil erosion and the alteration of surface strength, bulk density, soil moisture, temperature, and soil nutrients were quantified to gain an insight into the difficulty of revegetating altered, or modified, areas.Erosion is severe at Hollister Hills, particularly in coarse grained soils on steep slopes. Erosion displaced 0.5 and 3.0 metric tons per square meter on 2 trails on gravelly sandy loam, and 0.3 metric tons/m2 from a trail on sandy loam. The surface strength and bulk density increased while the soil moisture decreased in gravelly sandy loam, coarse sandy loam, sandy loam, and clay. Clay loam had an increased surface strength with variably increased bulk density and no decrease in soil moisture. Diurnal temperature fluctuations increased and organic material and soil nutrients decreased in soil modified by vehicles.These property changes increase the erosion potential of the soil, impede germination of seedlings, and slow natural revegetation. Management methods in ORV-use areas should include planning trails by prior application of the universal soil loss equation and soil surveys, trail closure before complete loss of the soil mantle, and revegetation of closed areas.  相似文献   
167.
ABSTRACT

Big data is gaining visibility and importance, and its use is attaining higher levels of influence within municipalities. Due to this proliferation smart cities are posed to deploy architectures toward managing energy for Electric Vehicles (EV) and orchestrate the production, consumption, and distributing of energy from renewable sources such as solar, wind etc. in communities also known as prosumption. In smart city domain, Enterprise Architecture (EA) can be employed to facilitate alignment between municipality goals and the direction of the city in relation to Information Technology (IT) that supports stakeholders within the city. Hence, the alignment between IT and goals of the city is a critical process to support the continued growth and improvement of city services and energy sustainability. However, despite several research effort focused on data architecture in smart city, there have been few studies aimed at exploring how EA can be applied in smart cities to support residential buildings and EV for energy prosumption in municipalities. Therefore, this study conducts an extensive review and develops an architecture that can be employed in smart city domain based on big data management for energy prosumption in residential buildings and EV. Furthermore, secondary data was employed to present a case study to show the applications of the developed architecture in promoting energy prosumption. Findings suggest that the architecture provides interoperable open real-time, online, and historical data in facilitating energy prosumption. Respectively, this study offers exchange of data for sharing energy resources and provides insights to improve energy prosumption services.  相似文献   
168.
PROBLEM: A number of studies have found that use of in-car phones by drivers can interfere with the cognitive processing necessary for making appropriate and timely vehicle control decisions. However, the specific linkage between communication-based distraction and unsafe decision-making has not been sufficiently explored. METHOD: In a closed-course driving experiment, 39 subjects were exposed to approximately 100 gaps each in a circulating traffic stream of eight vehicles on an instrumented test track that was wet about half the time. The subjects were at the controls of an instrumented car, which was oriented in a typical left-turn configuration (traffic-crossing situation in North America) and with parking brake on and the transmission in neutral. The subjects were instructed to press on the accelerator pedal when they felt that a gap was safe to accept. Their performances were monitored and incentives were provided for balancing safe decision-making with expeditious completion of the task. For half of the gap exposures (randomly assigned), each subject was required to listen and respond to a complex verbal message. RESULTS: When not distracted, the subjects' gap acceptance judgment was found to be significantly influenced by their age, the gap size, the speed of the trailing vehicle, the level of "indecision," and the condition of the track surface. However, when distracted, the subjects did not factor pavement surface condition into the decision process. On wet pavement, the subjects were judged to have initiated twice the level of potential collisions when distracted by the messages that they did when not distracted. DISCUSSION: Listening/responding to verbal messages may reduce the capacity of drivers to process adequately all the important information necessary for safe decision-making. The effects of the messages in our study seemed to cause the subjects to misjudge gap size and speed information when operating under the additional disadvantage of adverse pavement condition. SUMMARY: Attention to complex messages while making decisions about turning through gaps in an on-coming vehicle stream was associated with significantly increased unsafe decision making by subjects in our experiment when the additional complexity of wet surface condition was introduced. IMPACT ON INDUSTRY: While the results reflected a somewhat artificial situation where the measure was signaled intention to act rather than the act itself, nevertheless, they do strongly suggest a scenario in which mental distraction could contribute to crash risk. With the rapid proliferation of telematics in the vehicle market, even with the laudable objectives represented by the Intelligent Transportation Systems initiative, there is a danger of the primary task of the driver being subordinated to a perceived need to enhance information flow to/from the external "world." Industry and governments need to work together to ensure that apparently desirable in-vehicle communication improvements do not compromise safety.  相似文献   
169.
机组行为、时间余量与飞行安全间的关系探讨   总被引:2,自引:0,他引:2  
探讨机组行为、时间余量与飞行安全间的关系,为航空公司的机组训练和避免飞行事故及飞行事故征候的发生提供帮助。利用1996—2000年中国民用航空总局航空安全办公室下发的“飞行事故、航空地面事故和飞行事故征候统计的通知”中的资料,找出因机组行为错误导致的、与解决问题的时间余量关系密切的飞行事故和飞行事故征候案例。与飞行专家进行研讨和分析,探求飞行事故及其征候的发生与机组行为和时间余量间的关系。找出了因机组行为错误导致的、与解决问题的时间余量关系密切的飞行事故11起和飞行事故征候133起。其中因机组疏于监控飞机设备和状况、未发现问题存在或未明确所发生的问题的性质而无作为,使得解决问题的时间余量为零或接近零,从而无时间解决出现的问题,导致飞行事故3起和飞行事故征候96起;因机组发现问题存在并在明确所发生的问题的性质后,在一定时间余量内未能突破思维惯性的影响,做出了错误的决策,未能解决所发现的问题,导致飞行事故8起和飞行事故征候37起。飞行事故和飞行事故征候的发生与机组行为和时间余量的关系是,机组行为可以决定时间余量剩余的多少,时间余量的多少反过来决定机组采取何种措施解决当前的问题才能避免飞行事故和飞行事故征候的发生。  相似文献   
170.
In Europe targets have been laid down by EU legislation for the recycling rate of end-of-life vehicles to be achieved within the nearby future. It is illustrated in this paper that the definition of the recycling rate and the realisation of the imposed targets are very much dependent on different parameters such as the changing lifetime of the product and product design. It may seem obvious that the recycling rate is determined by various time-varying factors, however, this paper endeavours to describe and quantify the role of these factors on the recycling rate over time by the use of a dynamic systems model. This model permits the prediction of the recycling rate as a function of the numerous presented parameters, changing design scenarios etc. In addition, different definitions of the recycling rate will be presented and discussed. This will lead to a better understanding of the parameters affecting the recycling system and a more precise understanding of the recycling targets and their realisation as imposed by EU legislation. This paper focuses on cars, but the discussion and the definitions derived are equally valid for any end-of-life product.  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