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   166篇
  免费   7篇
公路运输   39篇
综合类   45篇
水路运输   47篇
铁路运输   20篇
综合运输   22篇
  2023年   1篇
  2022年   8篇
  2021年   2篇
  2020年   5篇
  2019年   7篇
  2018年   5篇
  2017年   8篇
  2016年   9篇
  2015年   8篇
  2014年   10篇
  2013年   31篇
  2012年   10篇
  2011年   16篇
  2010年   5篇
  2009年   9篇
  2008年   4篇
  2007年   3篇
  2006年   12篇
  2005年   5篇
  2004年   5篇
  2003年   1篇
  2002年   4篇
  2001年   1篇
  2000年   1篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
排序方式: 共有173条查询结果,搜索用时 15 毫秒
101.
针对汽车乘员舱热环境测试方法过于复杂、热舒适性评价方法实用性不强的问题,提出了车内亚稳态热环境的简化测试方案和驾驶员热舒适性评价方法.使用热舒适度测试仪实测了各季节驾驶员头部、胸腹部和脚部的环境参数,并对驾驶员进行热感觉预测.招募45位受试者进行主观热感觉调查作为热感觉实际值,确定了整体热感觉的最佳测量代表点.比较整体...  相似文献   
102.
基于瞳孔面积变动的公路隧道明暗适应时间   总被引:1,自引:0,他引:1  
公路隧道进出口照度剧烈变化,容易造成驾驶员明暗视觉适应困难,也是导致交通事故的重要原因,因此驾驶员明暗适应时间的确定是解析隧道视觉安全的基础问题.以26条典型公路隧道为例,利用IViewX HED Laptop眼动仪系统,对公路隧道路段驾驶员的视觉适应性进行了试验研究.根据大量试验数据建立了隧道进出口瞳孔面积及面积变化临界速度定量关系.在此基础上利用瞳孔面积速度/瞳孔面积临界速度比率κ来评价隧道路段视觉负荷,并建立了基于λ值的视觉明暗适应时间指标,最终得到隧道长度与视觉明暗适应时间的定量关系.对于中长隧道,暗适应时间一般不超过23 s,明适应时间不超过13s.  相似文献   
103.
为了分析在气温升高的状况下冻土退化对东北多年冻土地区路基稳定性的影响,假设气温年增长率为0.05℃,通过ANSYS有限元软件计算了不同地表状况和不同含冰量情况下,多年冻土最大季节融化深度变化,根据不同土质、不同含冰量的融沉系数,计算得到不同含冰量冻土的沉降量.结果表明:在气温逐年升高的状况下,含冰量大的土层沉降量大于含...  相似文献   
104.
The objective of this study is to examine the effect of road pricing on people’s tendency to adapt their current travel behavior. To this end, the relationship between changes in activity-travel behavior on the one hand and public acceptability and its most important determinants on the other are investigated by means of a stated adaptation experiment. Using a two-stage hierarchical model, it was found that behavioral changes themselves are not dependent on the perceived acceptability of road pricing itself, and that only a small amount of the variability in the behavioral changes were explained by socio-cognitive factors. The lesson for policy makers is that road pricing charges must surpass a minimum threshold in order to entice changes in activity-travel behavior and that the benefits of road pricing should be clearly communicated, taking into account the needs and abilities of different types of travelers. Secondly, earlier findings concerning the acceptability of push measures were validated, supporting transferability of results. In line with other studies, effectiveness, fairness and personal norm all had a significant direct impact on perceived acceptability. Finally, the relevance of using latent factors rather than aggregate indicators was underlined.  相似文献   
105.
为研究隧道进出口路段驾驶员明暗适应的特性及遮阳棚对明暗适应过程的影响规律,文章依托紫荆隧道(无遮阳棚)及巴朗山隧道(有遮阳棚)进行驾驶试验,以驾驶员瞳孔直径及其变化速率为研究参数,分析遮阳棚对隧道进出口路段明暗适应的缓冲效果。研究结果表明:暗适应过程90%以上发生在洞内段,明适应过程54.61%以上发生在洞内段;在隧道进口段暗适应过程中,通过遮阳棚时间为2 s时,最大瞳孔直径变化速率下降4.84%,通过遮阳棚时间为5 s时,最大瞳孔直径变化速率下降33.58%;在隧道出口段明适应过程中,通过遮阳棚时间为2 s时,最大瞳孔直径变化速率下降38.75%,通过遮阳棚的时间为5 s时,最大瞳孔直径变化速率下降49.97%。  相似文献   
106.
Visual imagery of costal morphological change processes must be accompanied by supporting information to make change processes understandable. We explored the influence of supporting information (graphs and numeric values) on perceptions of coastal morphological change processes through an experiment delivered to coastal recreationists. Supporting information was presented alongside four imagery types: human perspective digital elevation models (DEMs), human perspective digital photographs, aerial views of DEMs and aerial photography. We found neither the use of graphs nor numeric values influenced respondents' perceptions of coastal environmental change. However, perceptions varied significantly across imagery type; human perspective digital photographs and aerial photographs yielded higher ratings compared to human perspective DEMs and aerial views of DEMs. The results suggest supporting information representing increasingly severe rates of beach erosion and shoreline movement does not translate into perceptions of increasingly dramatic geophysical processes; this is consistent with previous empirical findings. The results also suggest individuals perceive coastal change processes as more severe when those processes are presented through photographs, particularly aerial photographs. Scientists, educators and coastal land use managers struggling to communicate the magnitude and severity associated with coastal geophysical processes are advised to use comparative aerial photography when possible.  相似文献   
107.
Sovereignty claims over insular features and maritime jurisdiction in the South China Sea have been disputed for decades, and a governance regime to address ocean-related issues is urgently needed. This article first introduces the notion of a regime, and examines details of cooperation mechanisms in the Polar Regions. Lessons that can be applied to the South China Sea include that both soft and hard law regimes work to bring States concerned together to cooperate on the “commons” issues even when military conflicts or sovereignty disputes still exist. Consensus among bordering States would be necessary to make the South China Sea a “zone of peace.” Mechanisms that accommodate the various sovereignty claims and freeze existing and new claims to, as well as to prohibit military activities in, the South China Sea are recommended. Lastly, if a cooperative mechanism were to be established in the future, the Arctic regime would be more applicable to the South China Sea than the Antarctic regime due to their geographic nature. Thus, only States bordering the South China Sea should have voting and decision-making rights in the cooperative mechanism. As always, the political will of all parties is paramount to the success of such an endeavor.  相似文献   
108.
The purpose of this paper is to compare improvement actions for reducing transport’s impact on climate from the shipper’s perspective. To that end, it introduces an evaluation tool for comparing improvement actions in transport systems in terms of transport costs, impact on climate, and barriers to implementation. Within the context of five international flows involving a food producer, three actions—namely, engaging intermodal transport, increasing load factors by double-stacking pallets, and using high-capacity vehicles—were evaluated. Shipment data were collected to calculate reductions in transport costs and impact on climate, whereas interviews with the food producer were conducted to identify barriers. Results showed that reductions in transport costs and impact on climate attributed to the improvement actions differed among the five flows. Engaging intermodal transport reduced the system’s impact on climate by 27–53%, double-stacking pallets by 0–23%, and using high-capacity vehicles by 7–15%, with differences primarily due to different freight densities. Concerning barriers to implementation, the improvement actions also varied by flow. Altogether, unlike other papers, which have examined improvement actions separately, this paper offers an evaluation tool for comparing several improvement actions at once, as applied to a particular empirical case. Shippers with multiple flows and several possible improvement actions can use the evaluation tool to efficiently reduce their systems’ impact on climate.  相似文献   
109.
随着“十四五”期间城市更新规划的编制实施,结合城市功能完善,城市水系统如何进行有机更新和同步提标改造,已成为今后城市建设的重要任务之一。从宏观、中观、微观三个层面,提出城市水系统更新规划要点,可为相关专业人员提供参考。  相似文献   
110.
人工湿地因环境效益显著、经济效益好、应用范围广等特点,近年来在污水处理中得到广泛应用。植物作为生态系统的生产者,是湿地系统最为核心的要素。基于国内外人工湿地植物的研究和应用情况,阐述了植物在尾水人工湿地中的应用情况、影响植物净化能力的因素,以及湿地植物应用中存在的问题等,并对尾水人工湿地植物的研究和应用做出了展望。在参考大量文献基础上对湿地植物选择的原则方法、影响因素及主要问题进行了系统性的总结,为实际工程应用提供依据和参考。  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