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   876篇
  免费   54篇
公路运输   202篇
综合类   329篇
水路运输   142篇
铁路运输   149篇
综合运输   108篇
  2024年   1篇
  2023年   1篇
  2022年   14篇
  2021年   17篇
  2020年   20篇
  2019年   13篇
  2018年   12篇
  2017年   17篇
  2016年   28篇
  2015年   28篇
  2014年   85篇
  2013年   67篇
  2012年   82篇
  2011年   82篇
  2010年   55篇
  2009年   53篇
  2008年   50篇
  2007年   94篇
  2006年   68篇
  2005年   40篇
  2004年   20篇
  2003年   16篇
  2002年   15篇
  2001年   9篇
  2000年   11篇
  1999年   6篇
  1998年   9篇
  1997年   3篇
  1996年   2篇
  1995年   2篇
  1994年   1篇
  1993年   2篇
  1992年   3篇
  1991年   2篇
  1989年   1篇
  1987年   1篇
排序方式: 共有930条查询结果,搜索用时 156 毫秒
41.
本文运用文献资料法、专家访谈法、问卷调查法、数理统计法对兰州市五人制足球运动的开展规模、教练员情况、场地设施、社会参与人群状况等问题进行调查分析,提出了针对性建议,旨在为进一步推动兰州市五人制足球的健康快速发展,同时促进兰州市足球运动的普及与提高尽一份力。  相似文献   
42.
In today’s world of volatile fuel prices and climate concerns, there is little study on the relationship between vehicle ownership patterns and attitudes toward vehicle cost (including fuel prices and feebates) and vehicle technologies. This work provides new data on ownership decisions and owner preferences under various scenarios, coupled with calibrated models to microsimulate Austin’s personal-fleet evolution.Opinion survey results suggest that most Austinites (63%, population-corrected share) support a feebate policy to favor more fuel efficient vehicles. Top purchase criteria are price, type/class, and fuel economy. Most (56%) respondents also indicated that they would consider purchasing a Plug-in Hybrid Electric Vehicle (PHEV) if it were to cost $6000 more than its conventional, gasoline-powered counterpart. And many respond strongly to signals on the external (health and climate) costs of a vehicle’s emissions, more strongly than they respond to information on fuel cost savings.Twenty five-year simulations of Austin’s household vehicle fleet suggest that, under all scenarios modeled, Austin’s vehicle usage levels (measured in total vehicle miles traveled or VMT) are predicted to increase overall, along with average vehicle ownership levels (both per household and per capita). Under a feebate, HEVs, PHEVs and Smart Cars are estimated to represent 25% of the fleet’s VMT by simulation year 25; this scenario is predicted to raise total regional VMT slightly (just 2.32%, by simulation year 25), relative to the trend scenario, while reducing CO2 emissions only slightly (by 5.62%, relative to trend). Doubling the trend-case gas price to $5/gallon is simulated to reduce the year-25 vehicle use levels by 24% and CO2 emissions by 30% (relative to trend).Two- and three-vehicle households are simulated to be the highest adopters of HEVs and PHEVs across all scenarios. The combined share of vans, pickup trucks, sport utility vehicles (SUVs), and cross-over utility vehicles (CUVs) is lowest under the feebate scenario, at 35% (versus 47% in Austin’s current household fleet). Feebate-policy receipts are forecasted to exceed rebates in each simulation year.In the longer term, gas price dynamics, tax incentives, feebates and purchase prices along with new technologies, government-industry partnerships, and more accurate information on range and recharging times (which increase customer confidence in EV technologies) should have added effects on energy dependence and greenhouse gas emissions.  相似文献   
43.
ATR技术在杭州湾跨海大桥跨海三角高程测量中的应用   总被引:1,自引:0,他引:1  
跨海高程控制测量是现代大型桥梁工程测量的难点,结合杭州湾跨海大桥施工高程测量控制网的建立,以ATR技术为硬件基础,介绍ATR三角高程测量的具体实施方法。经实测数据分析,采用ATR三角高程测量,在多项精度指标上均达到了国家三等水准测量的要求。  相似文献   
44.
润扬大桥悬索桥全站仪法挠度变形观测   总被引:2,自引:0,他引:2  
为科学评价桥梁结构体系的实际使用性能,大型桥梁竣工验收时必须进行静载试验。针对润扬大桥悬索桥静载试验工程项目,研究了利用全站仪进行桥梁挠度变形观测的方法。论文介绍了全站仪法测量桥梁挠度的原理和计算公式,并对全站仪法观测桥梁挠度变形值的测量精度进行了分析。通过到润扬大桥实地踏勘,制订了全站仪法挠度变形观测的具体方案。通过对全站仪实测数据和理论计算数据的比较和分析,证明了全站仪法大型桥梁挠度变形测量结果可靠,观测效率高。  相似文献   
45.
文章在分析铁路勘测设计现状的基础上,阐述了解决勘测设计一体化的中间环节,即站前专业间接口系统的重要性,提出了该系统的运行模式、实现方案,探讨了必须解决的技术难点,经实际运作证明该系统是可行的。  相似文献   
46.
Observing the rhythms of daily life: A six-week travel diary   总被引:2,自引:0,他引:2  
  相似文献   
47.
48.
城市综合交通调查在中国已有30余年的广泛实践,当前的信息化和大数据背景下正历经发展与变革.在分析城市综合交通调查现状问题的基础上,提出制定《城市综合交通体系规划交通调查导则》(以下简称《导则》)的必要性.从目标与总体框架、调查项目分类、术语定义、调查内容与问题选项分类、调查流程规范几个层面对《导则》的主要思想与关键内容进行解析.提出城市综合交通调查未来发展方向应是将信息化技术与传统调查手段结合,提高调查效率与质量,关注信息化手段未能涵盖的交通特征.  相似文献   
49.
Characteristics of the built environment (BE) have been associated with walk, transit, and bicycle travel. These BE characteristics can be used by transportation researchers to oversample households from areas where walk, transit, or bicycle travel is more likely, resulting in more observations of these uncommon travel behaviors. Little guidance, however, is available on the effectiveness of such built environment oversampling strategies. This article presents measures that can be used to assess the effectiveness of BE oversampling strategies and inform future efforts to oversample households with uncommon travel behaviors. The measures are sensitivity and specificity, positive likelihood ratio (LR+), and positive predictive value (PPV). To illustrate these measures, they were calculated for 10 BE-defined oversampling strata applied post-hoc to a Seattle area household travel survey. Strata with an average block size of <10 acres within a ¼ mile of household residences held the single greatest potential for oversampling households that walk, use transit, and/or bicycle.  相似文献   
50.
传统的航道水深测量方式,测量成本较高,而且,很多情况下,由于水浅等原因,较大的常规测量船不能到达,而难以测量.文中介绍了航道水深测量遥控测量船的设计原理和应用情况.遥控船上安装有测量系统,能够实现远程手动遥控测量和按预定航线自动导航测量.该船吃水浅、航速快、稳性好、遥控距离远,有2套动力系统,可远程自由切换,安全性高.2011年投入使用以来,取得了较好的效果.  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