全文获取类型
| 收费全文 | 969篇 |
| 免费 | 123篇 |
专业分类
| 公路运输 | 245篇 |
| 综合类 | 414篇 |
| 水路运输 | 214篇 |
| 铁路运输 | 128篇 |
| 综合运输 | 91篇 |
出版年
| 2025年 | 7篇 |
| 2024年 | 11篇 |
| 2023年 | 20篇 |
| 2022年 | 23篇 |
| 2021年 | 35篇 |
| 2020年 | 32篇 |
| 2019年 | 30篇 |
| 2018年 | 28篇 |
| 2017年 | 32篇 |
| 2016年 | 27篇 |
| 2015年 | 45篇 |
| 2014年 | 59篇 |
| 2013年 | 62篇 |
| 2012年 | 58篇 |
| 2011年 | 89篇 |
| 2010年 | 63篇 |
| 2009年 | 73篇 |
| 2008年 | 48篇 |
| 2007年 | 88篇 |
| 2006年 | 73篇 |
| 2005年 | 47篇 |
| 2004年 | 33篇 |
| 2003年 | 19篇 |
| 2002年 | 21篇 |
| 2001年 | 24篇 |
| 2000年 | 18篇 |
| 1999年 | 7篇 |
| 1998年 | 8篇 |
| 1997年 | 2篇 |
| 1996年 | 5篇 |
| 1994年 | 1篇 |
| 1992年 | 1篇 |
| 1991年 | 2篇 |
| 1990年 | 1篇 |
排序方式： 共有1092条查询结果，搜索用时 0 毫秒
161.
ABSTRACTPort activity plays an important role in facilitating international trade. Sufficient capacity is indispensable for a port to attract flows to a region and retain them. The capacity decision is the result of a trade-off between investment and waiting costs. Traditional methods to value expansion projects do not deal adequately with managerial flexibility in the face of uncertainty from different sources in the complex port environment. In this paper, real options (RO) models are identified as an alternative method to making project valuations and investment decisions, as they attribute the correct value to managerial flexibility under uncertainty. In order to be able to build and use such RO models for port capacity investment decisions, the sources and implications of uncertainty in the port and the different RO model specifications need to be understood. To this end, both the literature about uncertainty in the port context and the literature about real options models are reviewed in order to provide researchers who want to build their own decision-making models, with the necessary knowledge of both fields. The review makes clear that the complex interactions in and competition between the logistics chains and their actors coming together in ports have significant impacts on port capacity. Uncertainty is also caused by uncertain international trade flows and changes in legislation following new technologies and environmental impacts. An analysis of the components of some general RO models shows how the options of flexible output, investment size and timing are valued by RO models in a setting with demand uncertainty. Moreover, the review presents researchers with insights in how to deal with cooperative and competitive interactions in the chain, time to build, cyclical markets and legislation changes. It also shows how to value the expansion and the phased investment options. The new insights resulting from this review are subsequently combined in a framework that serves as a guideline to build RO models for port capacity investments. Finally, an exemplifying application of the framework is used to build an actual port capacity investment decision model. 相似文献
162.
Abstract Recent developments in the light rapid transit sector have introduced transit modes that are attempting to imitate the performance of others, e.g. buses with tram-like characteristics. The boundaries between existing definitions of what is a bus, tram or train are becoming blurred. For transport studies and practice this requires a review of how we define modes. This is not just a matter of semantics, but has safety and competition regulation implications for system operators. This paper proposes a structure to produce rail- and bus-based transit mode definitions and typology that are appropriate for modern use. A decision tree is used to classify and define the transit modes as guided-bus, trolley-bus, light rail and tram-train and is provided with example systems. The paper provides a robust definitional framework that allows transit system promoters, operators and other interested parties to have a consistent basis of reference when specifying and comparing rapid transit systems. 相似文献
163.
The development of behaviourally richer representations of the role of well-established and increasingly important influences on modal choice, such as trip time reliability and accounting for risk attitude and process rules, has moved forward at a fast pace in the context of automobile travel. In the public transport setting, such contributions have, with rare exception, not been considered. In this paper, we discuss and empirically illustrate the merits of advanced modelling developments aimed at improving our understanding of public transport choice, namely the inclusion of reliability in extended expected utility theoretic forms, to recognize risk attitude and perceptual conditioning, the consideration of passenger crowding and its inclusion in linear additive models, and the role of multiple heuristics in representing attribute processing as a way of conditioning modal choice. We illustrate the mechanics of introducing these behaviourally appealing extensions using a modal choice data set collected in Sydney. 相似文献
164.
This paper investigates the performance of a policy decision tool proposed for multi-objective decision under different policy interventions. This tool deals with the trade-off between mobility and equity maximization under environmental capacity constraints. Two system objectives, maximization of mobility and equity, are formulated in terms of the sum of total car ownership and number of trips, and the differences in accessibility between zones. Environmental capacities are based on production efficiency theory in which the frontier emission under maximum system efficiency is taken as environmental capacity. To examine the performance of the proposed model, three types of hypothetical policies (network improvement, population increase and urban sprawl) are formulated. Effects are simulated using data pertaining to Dalian City, China. Results show that the proposed model is capable of representing the trade-offs between mobility and equity based on different policy interventions. Compared with two extreme cases with the single objective of mobility maximization or equity maximization, the Pareto-optimal solutions provide more interesting practical options for decision makers. Taking the solution based on the maximum equity as an example, the policy of urban sprawl yields the most significant improvement in both emission and accessibility of the three scenarios. 相似文献
165.
166.
预防性养护是一种在路面状况尚处于良好情况下采取的对现有道路系统进行有计划的、基于费用效益的养护策略.养护措施的选择应针对不同路况采取不同的策略.以唐山市某国道工程为实例,介绍采用AHP -模糊综合评价法得到路面预防性养护的最佳措施. 相似文献
167.
针对艰险山区铁路建设中出现的长大坡道和线路方案决策时难以系统量化指标权重的问题,提出基于改进层次分析法（AHP）、改进熵权法和逼近理想解排序法（TOPSIS）的长大坡道线路方案评价方法,选取工程技术经济、工程地质、运营安全、生态保护4个方面12个评价指标,构建了山区铁路长大坡道线路方案综合优选评价体系,利用改进AHP-熵权法计算各指标的主观、客观权重,并进行组合赋权得到综合权重,结合TOPSIS法计算各线路方案与理想解的贴近度,并以渝昆高铁筠连至昭通段4个长大坡道线路方案对评价方法进行验证,计算各线路方案综合优越度,得出30‰坡度集中使用方案最优。结果表明：所提评价方法和评价体系具有较好的合理性和适用性,可为山区铁路长大坡道线路方案优选提供可靠的决策支持。 相似文献
168.
为了实现对整体浇筑梁预应力束的自动布置,提出预应力束自动布置的分步算法：第1步,基于桥梁弯矩内力包络图建立预应力束线形计算模型;第2步,基于线性规划原理,将弯曲能量最小作为目标函数,提出决策系数法计算预应力束数量,再以主梁应力作为控制条件对预应力束进行最终调整。与其他预应力优化算法相比,分步算法计及预应力束的构造要求,同时避免局部优化的缺陷。以柳州跨座式单轨桥梁为工程背景,基于分步算法在Matlab平台开发计算软件,计算柳州单轨3×30 m梁。研究结果表明：预应力束自动布置的分步算法能实现预应力束的合理布置,有较好的准确性,可在整体浇筑桥梁设计中推广应用。 相似文献
169.
为解决交叉口因BRT优先影响其他车辆通行问题,提出基于交叉口双站台的BRT 优先控制方法. 给出交叉口BRT双站台设置方法,对比分析BRT在交叉口单、双站台的平均延误. 根据BRT发车时刻、交叉口信号配时、BRT平均车速、交叉口间距及站台停靠时间等,制定 BRT站台预停靠方案和行车时刻表. 为确保BRT按照预停靠站台及时刻表运行,采用BRT车速引导与信号配时双重补偿修正BRT 实际离站时刻与时刻表的偏差. 以常州BRT 1 号线为例,对应用本文方法的5 个交叉口进行分析. 结果表明：BRT在每个站台实际离站时刻偏差范围为±5 s、±10 s、±20 s 时,本文优先控制方法显著减少BRT停车次数和延误,提高了BRT整体运营效率. 相似文献
170.
近年来全球新发重大传染病疫情不断出现,已成为人类社会必须防范应对的重大风险。公共交通在传染病疫情防控过程中承担着阻断病毒传播和保障复工复产的功能,疫情期间公共交通运行管理的决策需求和技术支撑体系与日常情况有显著差异。现有研究多针对公交日常运行决策需求展开,虽有少量针对突发公共事件的应急管理决策支持的研究,但多针对自然灾害和事故灾难场景,无法迁移应用于传染病疫情防控。基于此,以新型冠状病毒肺炎（COVID-19）疫情为例,综合考虑突发公共卫生事件应急管理流程和疫情防控实际情况,系统梳理疫情不同阶段的防控目标和决策需求,提出一种面向传染病疫情防控的公共交通运行管理决策支持系统框架,建立基于公共卫生事件案例库、多源数据融合库、公交数据分析技术库和公交防疫策略库的功能架构,并设计不同功能模块的算法模型。研究以厦门为例,对提出的决策支持系统的功能架构和算法模型进行验证。研究结果表明,构建公交乘客出行链的成功率为89.7%,并可应用于疫情不同阶段的关联客流分析、感染者同乘人员的追溯分析、医护人员等防疫人员的通勤出行识别、公交运行满载率监控等方面。研究成果不仅对传染病疫情防控有实用价值,而且对突发公共事件应急管理决策支持方法亦有理论贡献。 相似文献