全文获取类型
收费全文 | 2791篇 |
免费 | 190篇 |
专业分类
公路运输 | 724篇 |
综合类 | 1268篇 |
水路运输 | 211篇 |
铁路运输 | 340篇 |
综合运输 | 438篇 |
出版年
2024年 | 24篇 |
2023年 | 32篇 |
2022年 | 52篇 |
2021年 | 123篇 |
2020年 | 133篇 |
2019年 | 85篇 |
2018年 | 81篇 |
2017年 | 88篇 |
2016年 | 108篇 |
2015年 | 113篇 |
2014年 | 267篇 |
2013年 | 232篇 |
2012年 | 252篇 |
2011年 | 237篇 |
2010年 | 178篇 |
2009年 | 182篇 |
2008年 | 146篇 |
2007年 | 197篇 |
2006年 | 132篇 |
2005年 | 72篇 |
2004年 | 47篇 |
2003年 | 43篇 |
2002年 | 26篇 |
2001年 | 36篇 |
2000年 | 22篇 |
1999年 | 7篇 |
1998年 | 10篇 |
1997年 | 11篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有2981条查询结果,搜索用时 78 毫秒
111.
山区旅游道路桥梁设计应遵循美观和有利环保的原则,考虑“因地制宜、就地取材、便于施工和养护”等因素,在桥梁结构选择、耐久性、抗震设计等方面应加强安全设计。 相似文献
112.
Travel demand forecasting is subject to great uncertainties. A systematic uncertainty analysis can provide insights into the level of confidence on the model outputs, and also identify critical sources of uncertainty for enhancing the robustness of the travel demand model. In this paper, we develop a systematic framework for quantitative uncertainty analysis of a combined travel demand model (CTDM) using the analytical sensitivity-based method. The CTDM overcomes limitations of the sequential four-step procedure since it is based on a single unifying rationale. The analytical sensitivity-based method requires less computational effort than the sampling-based method. Meanwhile, the uncertainties stemming from inputs and parameters can be treated separately so that the individual and collective effects of uncertainty on the outputs can be clearly assessed and quantified. Numerical examples are finally used to demonstrate the proposed sensitivity-based uncertainty analysis method for the CTDM. 相似文献
113.
This study investigated the contribution of psychological factors in explaining the choice of transportation mode in six Asian countries. Data were collected from 1118 respondents in Japan, Thailand, China, Vietnam, Indonesia, and the Philippines. The dependent variable was the intention to use one of three modes for work travel after getting a job: car, public transit, or other modes. The explanatory variables were three attitude factors taken from a previous study, including: 1/symbolic affective, reflecting affective motives of travel mode use; 2/instrumental, referring to functional attributes of travel modes; and 3/social orderliness which represents for environmental friendliness, safety, altruism, quietness et cetera. Several logit model estimates were made using the samples from the six countries separately and together. We obtained three main findings. First, attitude variables about the car were all significant determinants for the entire sample from Asian countries. Second, the social orderliness aspect of public transit was a common concern of respondents from developing countries in selecting this mode for work trips. Third, in countries in which the intent to use a car was not very high, attitude factors about the car were found to be significant determinants of the behavioral intention to commute by car but were less significant in countries in which the desire to use a car was high. 相似文献
114.
路基病害治理、路基加宽和路基防护是公路改建工程的重要组成部分,结合公路改建工程实例,就其原有路基病害加以分析,并提出了针对性的路基改建设计方案,为类似道路改建工程提供参考。 相似文献
115.
分析了旧水泥混凝土路面板产生裂缝的原因及破坏类型,对实体工程裂缝进行调查分析,介绍了在旧路加铺改造中采用的针对轻、中、重裂缝的处治方法与施工工艺,通过实体工程应用对其使用效果进行了评价。 相似文献
116.
The evacuation operations problem aims to avoid or mitigate the potential loss of life in a region threatened or affected by a disaster. It is shaped to a large extent by the evolution of evacuation traffic resulting from the demand–supply interactions of the associated transportation network. Information-based control is a strategic tool for evacuation traffic operations as it can enable greater access to the affected population and more effective response. However, comparatively few studies have focused on the implementation of information-based control in evacuation operations. This study develops a control module for evacuation operations centered on addressing the demand–supply interactions by using behavior-consistent information strategies. These strategies incorporate the likely responses of evacuees to the information provided in the determination of route guidance information. The control module works as an iterative computational process involving an evacuee route choice model and a control model of information strategies to determine the route guidance information to direct evacuation traffic so as to approach a desired network traffic flow pattern. The problem is formulated as a fuzzy logic based optimization framework to explicitly incorporate practical concerns related to information dissemination characteristics and social equity in evacuation operations. Numerical experiments highlight the importance of accounting for the demand–supply interactions, as the use of behavior-consistent information strategies can lead evacuee route choices to approach the operator-desired proportions corresponding to the desired traffic pattern. The results also indicate that while a behavior-consistent information strategy can be effective, gaps with the desired route proportions can exist due to the discrete nature of the linguistic messages and the real-world difficulty in accurately modeling evacuees’ actual route choice behavior. 相似文献
117.
118.
基于非参数回归的快速路行程速度短期预测算法 总被引:1,自引:0,他引:1
基于北京市快速路上的检测器所采集的历史数据,经过数据筛选,剔除判别,小波滤噪平稳处理,聚类分析等过程,建立了交通状态演变系列的历史样本数据库。基于所构建的历史数据库,通过数值试验,确定了状态向量、距离匹配原则,K近邻值等参量,构建了一种基于K近邻的非参数回归短时交通预测模型,实现了对路段行程速度的短时预测。最后,利用随机选取的历史数据系列对预测模型的精度进行了检验。结果表明,预测算法的精度可以达到90%以上,可以很好地满足ITS应用系统对于交通预测数据的精度要求。 相似文献
119.
120.