全文获取类型
收费全文 | 954篇 |
免费 | 15篇 |
专业分类
公路运输 | 324篇 |
综合类 | 198篇 |
水路运输 | 37篇 |
铁路运输 | 31篇 |
综合运输 | 379篇 |
出版年
2024年 | 3篇 |
2023年 | 1篇 |
2022年 | 7篇 |
2021年 | 11篇 |
2020年 | 26篇 |
2019年 | 9篇 |
2018年 | 38篇 |
2017年 | 20篇 |
2016年 | 39篇 |
2015年 | 41篇 |
2014年 | 43篇 |
2013年 | 57篇 |
2012年 | 74篇 |
2011年 | 90篇 |
2010年 | 74篇 |
2009年 | 90篇 |
2008年 | 47篇 |
2007年 | 94篇 |
2006年 | 62篇 |
2005年 | 51篇 |
2004年 | 24篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 11篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 5篇 |
排序方式: 共有969条查询结果,搜索用时 31 毫秒
101.
Multi-objective optimization of a road diet network design 总被引:1,自引:0,他引:1
Keemin Sohn 《Transportation Research Part A: Policy and Practice》2011,45(6):499-511
The present study focuses on the development of a model for the optimal design of a road diet plan within a transportation network, and is based on rigorous mathematical models. In most metropolitan areas, there is insufficient road space to dedicate a portion exclusively for cyclists without negatively affecting existing motorists. Thus, it is crucial to find an efficient way to implement a road diet plan that both maximizes the utility for cyclists and minimizes the negative effect on motorists. A network design problem (NDP), which is usually used to find the best option for providing extra road capacity, is adapted here to derive the best solution for limiting road capacity. The resultant NDP for a road diet (NDPRD) takes a bi-level form. The upper-level problem of the NDPRD is established as one of multi-objective optimization. The lower-level problem accommodates user equilibrium (UE) trip assignment with fixed and variable mode-shares. For the fixed mode-share model, the upper-level problem minimizes the total travel time of both cyclists and motorists. For the variable mode-share model, the upper-level problem includes minimization of both the automobile travel share and the average travel time per unit distance for motorists who keep using automobiles after the implementation of a road diet. A multi-objective genetic algorithm (MOGA) is mobilized to solve the proposed problem. The results of a case study, based on a test network, guarantee a robust approximate Pareto optimal front. The possibility that the proposed methodology could be adopted in the design of a road diet plan in a real transportation network is confirmed. 相似文献
102.
103.
针对二灰砂砾在实际使用中存在离析、早期强度较低、耐冲刷性一般等缺点,通过合理级配设计使得二灰砂砾具有良好的路用性能是保障其应用的关键。通过K法对二灰砂砾配合比优化,经过室内测试分析,提出了基于性能设计原则的二灰砂砾混合料合理的配合比。 相似文献
104.
采用裂缝率、车辙、横向力系数和功能性破损率四个指标衡量沥青路面是否达到预防性养护标准。结合选取的锦阜、锦朝高速公路代表性路段检测数据分析评价,负指数函数y=a.e-bx能够很好地表征路面单值指标性能变化规律。通过分析预测,得到了锦阜、锦朝高速公路最佳的预防性养护年限。 相似文献
105.
106.
文章结合广西路网工程建设背景、路网工程建设程序、路线设计步骤,介绍了以公路运行安全、新征用土地数量、工程造价、地形地物、方便施工等为原则控制路线的设计方法,同时针对当前路网工程路线设计中存在的主要问题,提出了相关的处理措施。 相似文献
107.
108.
109.
基于我国道路货物运输的发展现状,以探索推行道路货物运输网络化的发展模式为主线,以提高道路货物运输组织效率和行业发展水平为最终目标,阐述道路货物网络化运输的概念及内涵,对网络化运输服务进行了划分,构建了我国推行道路货物网络化运输的两类发展模式,并利用图示和文字结合的方式对其进行了分析评价。 相似文献
110.
First and second generation biofuels are among few low-carbon alternatives for road transport that currently are commercially available or in an early commercialization phase. They are thus potential options for meeting climate targets in the medium term. For the case of Sweden, we investigate cost-efficient use of biofuels in road transport under system-wide CO2 reduction targets to 2050, and the effects of implementation of targets for an almost fossil-free road transport sector to 2030. We apply the bottom-up, optimization MARKAL_Sweden model, which covers the entire Swedish energy system including the transport sector. For CO2 reductions of 80% to 2050 in the Swedish energy system as a whole, the results of the main scenario show an annual growth rate for road transport biofuels of about 6% from 2010 to 2050, with biofuels accounting for 78% of road transport final energy use in 2050. The preferred biofuel choices are methanol and biomethane. When introducing additional fossil fuel phase-out policies in road transport (−80% to 2030), a doubling of the growth rate to 2030 is required and system CO2 abatement costs increases by 6% for the main scenario. Results imply that second generation biofuels, along with energy-efficient vehicle technologies such as plug-in hybrids, can be an important part of optimized system solutions meeting stringent medium-term climate targets. 相似文献