全文获取类型
收费全文 | 13026篇 |
免费 | 600篇 |
专业分类
公路运输 | 4439篇 |
综合类 | 3462篇 |
水路运输 | 2794篇 |
铁路运输 | 2524篇 |
综合运输 | 407篇 |
出版年
2024年 | 48篇 |
2023年 | 112篇 |
2022年 | 186篇 |
2021年 | 413篇 |
2020年 | 420篇 |
2019年 | 213篇 |
2018年 | 138篇 |
2017年 | 204篇 |
2016年 | 230篇 |
2015年 | 374篇 |
2014年 | 967篇 |
2013年 | 804篇 |
2012年 | 1304篇 |
2011年 | 1313篇 |
2010年 | 882篇 |
2009年 | 862篇 |
2008年 | 866篇 |
2007年 | 1143篇 |
2006年 | 1088篇 |
2005年 | 654篇 |
2004年 | 373篇 |
2003年 | 244篇 |
2002年 | 195篇 |
2001年 | 156篇 |
2000年 | 77篇 |
1999年 | 75篇 |
1998年 | 40篇 |
1997年 | 50篇 |
1996年 | 44篇 |
1995年 | 23篇 |
1994年 | 20篇 |
1993年 | 21篇 |
1992年 | 16篇 |
1991年 | 23篇 |
1990年 | 10篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
This paper presents a general formulation for optimization of horizontal road alignment, composed of tangential segments and circular curves suitably connected with transition curves (clothoids). It consists of a constrained optimization problem where the objective function is given by a line integral along the layout. The integrand is a function representing the cost of the road going through each point and, by considering different costs, a wide range of problems can be included in this formulation. To show it, we apply this methodology to three different situations. The two first cases are related with the design of a new road layout and used to solve a pair of academic examples. The third problem deals with the improvement of a road adapting the old path to current legislation, and it is solved taking as case study the reconstruction project for a regional road (NA-601) in the north of Spain. 相似文献
103.
104.
Building safe and effective roundabouts requires optimizing traffic (operational) efficiency (TE) and traffic safety (TS) while taking into account geometric factors, traffic characteristics and local constraints. Most existing simulation-based optimization models do not simultaneously optimize all these factors. To capture the relationship among geometry, efficiency and safety, we put forward a model formulation in this paper. We present a new multi-criteria and simultaneous multi-objective optimization (MOO) model approach to optimize geometry, TE and TS of urban unsignalized single-lane roundabouts. To the best of our knowledge, this is the first model that uses the multi-criteria decision-making method known as analytic hierarchy process to evaluate and rank traffic parameters and geometric elements of urban single-lane roundabouts. The model was built based on comprehensive review of the research literature and existing roundabout simulation software, a field survey of 61 civil and traffic expert engineers in Croatia, and field studies of roundabouts in the Croatian capital city of Zagreb. We started from the basis of Kimber’s capacity model, HCM2010 serviceability model, and Maycock and Hall's accident prediction model, which we extended by adding sensitivity analysis and powerful MOO procedures of the bounded objective function method and interactive optimization. Preliminary validation of the model was achieved by identifying the optimal and most robust of three geometric alternatives (V.1-V.3) for an unsignalized single-lane roundabout in Zagreb, Croatia. The geometric parameters in variant V.1 had significantly higher values than in the existing design V.0, while approaches 1 and 3 in variant V.2 were enlarged as much as possible within allowed spatial limits and Croatian guidelines, reflecting their higher traffic demand. Sensitivity analysis indicated that variant V.2 showed the overall highest TE and TS across the entire range of traffic flow demand and pedestrian crossing flow demand at approaches. At the same time, the number of predicted traffic accidents was similar for all three variants, although it was lowest overall for V.2. The similarity in predicted accident frequency for the three variants suggests that V.2 provides the greatest safety within the predefined constraints and parameter ranges explored in our study. These preliminary results suggest that the proposed model can optimize geometry, TE and TS of urban single-lane roundabouts. 相似文献
105.
介绍连续配筋混凝土路面的基本概念,说明我国CRCP的结构设计理论和设计方法,可为该技术在我国的推广应用提供理论支撑. 相似文献
106.
文章结合高速公路U型桥台开裂的典型工程实例,分析了U型桥台裂缝产生的原因,提出了相应的加固处治方案,并阐述了加固方案的实施要点与处治效果。 相似文献
107.
108.
109.
美国施工区交通管理的关键技术和策略 总被引:1,自引:0,他引:1
王忠仁 《重庆交通大学学报(自然科学版)》2012,31(3):425-431,464
施工期间的交通组织管理是项目成功的基本保证。通过对施工区基本交通分析技术入手,深入阐述了美国施工区交通管理的量化指标、管理程序,及公众信息、旅行者信息、事件管理、施工策略和需求管理等5大基本管理策略。对全面了解美国施工区交通组织和管理实践,提高我国道路施工期间的交通组织和管理水平具有重要的借鉴意义。 相似文献
110.
随着我国高速铁路事业的发展,旅客对车内照明环境品质的要求越来越高,在我国高速列车照明设计中广泛采用LED灯具作为光源。通过对高速动车组车载灯具与25T型列车传统车载灯具的测试对比,总结出LED灯具在发光效率等方面相对于传统灯具的优势,为高速动车组室内照明设计提供依据。 相似文献