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   259篇
  免费   11篇
  国内免费   5篇
安全科学   108篇
废物处理   3篇
环保管理   40篇
综合类   58篇
基础理论   8篇
污染及防治   25篇
评价与监测   15篇
社会与环境   15篇
灾害及防治   3篇
  2025年   1篇
  2024年   3篇
  2023年   7篇
  2022年   7篇
  2021年   20篇
  2020年   23篇
  2019年   19篇
  2018年   7篇
  2017年   9篇
  2016年   10篇
  2015年   3篇
  2014年   5篇
  2013年   8篇
  2012年   14篇
  2011年   22篇
  2010年   9篇
  2009年   15篇
  2008年   16篇
  2007年   4篇
  2006年   8篇
  2005年   16篇
  2004年   14篇
  2003年   9篇
  2002年   3篇
  2001年   5篇
  2000年   2篇
  1999年   3篇
  1998年   2篇
  1997年   3篇
  1996年   2篇
  1995年   1篇
  1994年   4篇
  1985年   1篇
排序方式: 共有275条查询结果,搜索用时 0 毫秒
131.
    
Abstract

Objective: Road departures are one of the most severe crash modes in the United States. To help reduce this risk, vehicles are being introduced in the United States with lane departure warning (LDW) systems, which warn the driver of a departure, and lane departure prevention (LDP) systems, which assist the driver in steering back to the roadway. Previous studies have estimated that LDW/LDP systems may prevent one third of drift-out-of-lane road departure crashes. This study investigates the crashes that were not prevented, to potentially set research priorities for next-generation road departure prevention systems.

Methods: The event data recorder (EDR) data from 128 road departure crashes in the National Automotive Sampling System Crashworthiness Data System (NASS-CDS) from 2011 to 2015 were mapped onto the vehicle trajectory and simulated with LDW/LDP to assess the potential for crash avoidance. The model predicted that 63–83% of single-vehicle road departure crashes may not be prevented by an LDW system and 49% may not be prevented by an LDP system.

Results and Conclusions: For LDP systems, which were assumed to have zero latency, no crashes were avoided if the time-to-collision (TTC) from lane crossing to impact was less than 0.55?s. Obstacles such as guardrails and traffic barriers, which tend to be very close to the road, were more common among the remaining crashes. The study shows that LDW/LDP systems are limited by two factors, driver reaction time and TTC to the roadside object. Thus, earlier driver response and longer TTC may help in these situations.  相似文献   
132.
汽车驾驶员驾驶疲劳监测技术研究进展   总被引:23,自引:5,他引:23  
当今驾驶疲劳已成为引发交通事故的主要原因,但由于其形成原因复杂,监测技术和手段都还不成熟.驾驶疲劳客观监测技术是目前研究的热点,主要包括对驾驶员脑电图、心电图、眼睑眨动、头部运动轨迹、方向盘的运动、车辆行驶方向等的监测技术.由于上述监测技术都存在一定的局限性,因此,笔者认为,今后的研究应该从以下4个方面着手进行:①研制非接触性高灵敏度传感器;②寻求新的监测指标和方法;③将多传感器信息融合技术应用于监测技术中;④研制高性价比的监测装置.  相似文献   
133.
    
Introduction: Safety of pedestrians depends, among other factors, on their behavior while crossing the road. This study aims to assess behaviors of pedestrians at signalized crosswalks. Method: Following a literature review and a pilot study, 25 vital pedestrian crossing factors and behaviors were determined. Then data was randomly collected for 708 pedestrians at 10 lighted crossings in Sharjah (UAE), five at road intersections and five mid-block crossings. Results: Results indicated that 17.4% of pedestrians observed crossed partly or fully on red and that crossing speed was 1.22 m/s, on the average, which is slightly faster than most speeds recorded in the literature. Moreover, female pedestrians were more likely to cross while chatting with others, less likely to cross on red, and more likely to walk slower than male pedestrians. Results also showed that pedestrians who crossed at road intersections walked slower than those who crossed at mid-block crossings. It was also found that longer red pedestrian times and narrower roads tended to encourage pedestrians to cross on red and that the majority of pedestrians did not look around before crossing. Practical implications: Use of the Health Belief Model for pedestrian safety are discussed.  相似文献   
134.
    
An approach to transportation risk analysis for road and rail transport of dangerous goods is proposed, which is based on the use of geographic information systems (GIS) to manage territorial information, coupled with a product data bank in a risk evaluation tool. Such an approach enables to accurately take into account the local data affecting risk analysis, such as population, accident rate, and weather conditions along all the route, by means of a system which can be easily updated. The resulting risk evaluation tool assists in the step of route identification and allows to rapidly perform an accurate transportation risk analysis, for a single transportation event as well as for multiple substances, trips and itineraries.  相似文献   
135.
Current United States National Park Service (NPS) management is challenged to balance visitor use with the environmental and social consequences of automobile use. Wildlife populations in national parks are increasingly vulnerable to road impacts. Other than isolated reports on the incidence of road-related mortality, there is little knowledge of how roads might affect wildlife populations throughout the national park system. Researchers at the Western Transportation Institute synthesized information obtained from a system-wide survey of resource managers to assess the magnitude of their concerns on the impacts of roads on park wildlife. The results characterize current conditions and help identify wildlife-transportation conflicts. A total of 196 national park management units (NPS units) were contacted and 106 responded to our questionnaire. Park resource managers responded that over half of the NPS units’ existing transportation systems were at or above capacity, with traffic volumes currently high or very high in one quarter of them and traffic expected to increase in the majority of units. Data is not generally collected systematically on road-related mortality to wildlife, yet nearly half of the respondents believed road-caused mortality significantly affected wildlife populations. Over one-half believed habitat fragmentation was affecting wildlife populations. Despite these expressed concerns, only 36% of the NPS units used some form of mitigation method to reduce road impacts on wildlife. Nearly half of the respondents expect that these impacts would only worsen in the next five years. Our results underscore the importance for a more systematic approach to address wildlife-roadway conflicts for a situation that is expected to increase in the next five to ten years.  相似文献   
136.
中国特大城市的公路交通设施规模庞大而复杂,主要包括公路、城市道路、公路运输枢纽场站。本文实测了北京市有代表性公路交通设施场界噪声,分析了其不同道路等级(或不同客货公路运输枢纽)、不同车流量、不同时段情况下的噪声影响程度大小,为北京市公路交通设施的规划研究提供参考。  相似文献   
137.
通过对齐齐哈尔市城区"十一五"期间区域声环境质量、道路交通声环境质量、功能区噪声数据的分析,揭示我市5年间城区声环境质量的变化,并论述了其变化的原因,提出了"十二五"期间改善声环境质量的对策。  相似文献   
138.
    
The natural gas vehicle market is rapidly developing throughout the world, and the majority of such vehicles operate on compressed natural gas(CNG). However, most studies on the emission characteristics of CNG vehicles rely on laboratory chassis dynamometer measurements, which do not accurately represent actual road driving conditions. To further investigate the emission characteristics of CNG vehicles, two CNG city buses and two CNG coaches were tested on public urban roads and highway sections. Our results show that when speeds of 0–10 km/hr were increased to 10–20 km/hr, the CO_2, CO, nitrogen oxide(NO_x), and total hydrocarbon(THC) emission factors decreased by(71.6 ± 4.3)%,(65.6 ± 9.5)%,(64.9 ± 9.2)% and(67.8 ± 0.3)%, respectively. In this study, The Beijing city buses with stricter emission standards(Euro Ⅳ) did not have lower emission factors than the Chongqing coaches with Euro Ⅱ emission standards. Both the higher emission factors at 0–10 km/hr speeds and the higher percentage of driving in the low-speed regime during the entire road cycle may have contributed to the higher CO_2 and CO emission factors of these city buses. Additionally, compared with the emission factors produced in the urban road tests, the CO emission factors of the CNG buses in highway tests decreased the most(by 83.2%), followed by the THC emission factors, which decreased by 67.1%.  相似文献   
139.
公平、合理地分担外部性环境成本是实现道路交通资源最优配置的前提条件之一,而环境成本货币化评估是实现道路交通政策体现环境公平性的重要内容。介绍了在国内外对道路外部成本的研究成果,在已有研究的基础上,将我国道路交通发展的环境成本主要分解为生态影响、环境污染和温室气体排放三类,并以借助环境经济学理论基础,对给出的道路交通生态影响、环境污染和温室气体排放的货币化方法估算模型分别进行了探讨。随后,以安徽省某高速公路为例,计算出道路建设及运营的环境成本占工程总投资的7.31%,结果表明环境成本货币化有利于明确道路建设的环境影响,并纳入成本核算中。  相似文献   
140.
道路交通环境影响评价的物元模型   总被引:5,自引:0,他引:5  
分析了城市道路交通环境影响因素,提出了一套道路交通环境影响评价指标体系,并应用物元分析理论建立了相应的评价物元模型  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