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   255篇
  免费   7篇
公路运输   33篇
综合类   14篇
水路运输   87篇
铁路运输   7篇
综合运输   121篇
  2022年   3篇
  2021年   5篇
  2020年   9篇
  2019年   7篇
  2018年   15篇
  2017年   9篇
  2016年   14篇
  2015年   9篇
  2014年   5篇
  2013年   48篇
  2012年   19篇
  2011年   17篇
  2010年   11篇
  2009年   21篇
  2008年   12篇
  2007年   9篇
  2006年   5篇
  2005年   8篇
  2004年   6篇
  2003年   8篇
  2002年   1篇
  2001年   5篇
  2000年   1篇
  1999年   2篇
  1998年   3篇
  1997年   2篇
  1995年   2篇
  1994年   2篇
  1991年   2篇
  1985年   1篇
  1982年   1篇
排序方式: 共有262条查询结果,搜索用时 0 毫秒
191.
Transportation - Considering the role of behavioral and environmental factors on road accidents and traffic intensities, the characterization of vehicle use and driver behavior opens new...  相似文献   
192.
Transportation - Hybrid discrete choice (HDC) modeling requires indicators to allow for the identification of latent variables. An indicator usually expresses the level of agreement of a respondent...  相似文献   
193.
Transportation - This article examines the differences in commuting length between native and immigrant employees in Spain, a relevant issue since immigrants' longer commuting times may, among...  相似文献   
194.
This contribution investigates the economic benefits of using weather ship routing on Short Sea Shipping (SSS) activities. The investigation is supported with the development of a ship routing system based on pathfinding algorithm, the parametrization of the wave effect on navigation, and the use of high-resolution meteo-oceanographic predictions. The optimal ship routing analysis is investigated in a European SSS system: the link between Spanish and Italian ports. The results show the economic benefits using ship routing in SSS during energetic wave episodes. The rate of cost savings may reach 18% of the total costs under particular bad weather conditions in the navigation area. The work establishes the basis of further developments in optimal route applied in relatively short distances and its systematic use in the SSS maritime industry.  相似文献   
195.
Studies that link human behaviour to the influence of weather have historically been conducted in such fields as tourism, marketing and leisure. In most studies that jointly examine weather and the mode of transport, only open-air transportation has been considered (for example, bicycle, motorcycle or walking). This focus, together with the habitual use of data collected with automatic devices and a lack of studies that analyse this issue using stated preference data, are the main reasons motivating this paper. This paper aims to analyse the influence of weather and the density of traffic on the choice of transport mode. A case study is conducted in an access/egress corridor located in the city of Barcelona (Spain). Two data sources were used: revealed preference and stated preference data. Modelling techniques using mixed data enabled the stronger features from both data sources to be captured. Finally, we discuss how the selection of different alternative specific constants in models estimated using mixed data could generate unrealistic forecasting results if environmental changes are expected in the actual market.  相似文献   
196.
Transport projects involve costs and benefits. Benefits to users appear in the form of more and/or better trips. Once the neoclassical idea of demand is accepted, the variation of utility levels underlie the measurement of benefits. In the evaluation process, benefits have to be compared with costs, and this can be done converting utility into monetary units. This paper deals with the treatment of this problem, starting with the general relation among utility, demand and the various forms of consumers’ surplus, to move further into the particular forms that these relations take in the transport field. The rule‐of‐a‐half is followed from the intuitive initial justification to a strict (and general) analytical derivation. More rigorous forms of users’ surplus variation are then presented for fairly general cases, including both aggregate and disaggregate transport demand models, emphasizing the manner in which welfare measures are derived in each case. Discussion is centred around the comparative advantages and limitations of available approaches, searching for improvements in demand formulation and benefits measurement.  相似文献   
197.
Transportation - The need to transition away from the current car-dominated transport system is well documented in sustainability, health and transportation literatures. Despite growing interest in...  相似文献   
198.
Transportation - Simulation studies suggest that pooled on-demand services (also referred to as Demand Responsive Transport, ridesharing, shared ride-hailing or shared ridesourcing services) have...  相似文献   
199.
200.
免疫抑制因子对宫颈癌患者来源的树突状细胞的体外作用   总被引:2,自引:0,他引:2  
目的 观察白细胞介素 10 (IL 10 )及血管内皮生长因子 (VEGF)对宫颈癌患者来源的树突状细胞 (DC)的体外抑制作用。方法 培养宫颈癌患者自体DC的小牛血清体系中加入粒 -巨噬细胞集落刺激因子 (GM CSF)、IL 4和肿瘤坏死因子 α(TNF α) ;流式细胞术检测免疫表型 ;甲基噻唑蓝法 (MTT)法检测异体混和淋巴细胞反应 (MLR)和细胞毒实验 ;酶联免疫吸附实验 (ELISA)法检测培养细胞上清液中IL 10和VEGF含量。结果  10例宫颈癌患者外周血单个核细胞培养 10d后 ,获得 (40± 2 0 ) %的DC ,此类DC共刺激分子的表达减低 ,刺激自体T细胞杀伤癌细胞能力不足 ,分泌IL 10及VEGF的含量却升高。结论 IL 10和VEGF抑制了宫颈癌患者自体DC的功能。  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