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71.
    
Improving freight connectivity is increasingly a topic at the centre of the international trade and transport policy agendas. An examination of available documents and studies in both the policy-making and the academic fields shows that the concept of freight connectivity has often been defined in different ways, and thus has taken a variety of meanings. This poses the question on what connectivity is and what are its determinants in the context of international trade. We are not aware of any studies that have analysed, in a systematic way, the different perspectives and determinants of freight connectivity so as to increase access to international markets. This paper seeks to fill this gap by performing a systematic literature review that spans disciplines such as Transport Engineering, Transport and International Economics, and Supply Chain Management. The outcome of this examination is a multidisciplinary framework that hopefully will help stakeholders to understand freight connectivity to international markets better, as well as guide future research and analysis in policy-making.  相似文献   
72.
    
The average delay experienced by vehicles at a signalized intersection defines the level of service (LOS) at which the intersection operates. A major challenge in this regard is the ability to accurately estimate all the components underlying the overall control delay, including the uniform, incremental and initial queue delays. This paper tackles this challenging task by proposing a novel exact model of the uniform control delay component with a view to enhancing the accuracy of the existing approximate models, notably, the one reported in the Highway Capacity Manual 2010. Both graphical and analytical proofs are employed to derive exact closed‐form expressions for the uniform control delay at undersaturated signalized intersections. The high degree of accuracy of the proposed models is analysed through extensive simulations to demonstrate their abilities to exactly characterize the performance of real‐life intersections in terms of the resulting vehicle delay. Unlike the existing widely adopted uniform delay models, which tend to overestimate the LOS of real‐life intersections, the delay models introduced in this paper have the merit of exactly capturing such a LOS. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
73.
    
This article examines fundamental questions concerning the origins and evolution of academic transport studies and the dynamics of its historical development. These fundamental questions are generally little discussed, yet are vital in gaining a better understanding of how the subject is driven forward. This article therefore attempts to answer these questions by taking the UK as a case study, with the principal method being evidence from semi-structured interviews with 20 senior figures integrally involved in the development of the subject. The characterization of transport studies provided by Allsop is employed as an analytical framework, enabling the construction of a historical narrative that can provide salient insights. Thus, it is argued that for academic transport studies the degree of early cross-fertilization with public arenas has meant that subsequent developments have been shaped by the subject's contextual environment. Most prominent among these developments has been the trend towards wider disciplinary breadth. This article examines the evolution of these processes, while the concluding section discusses their implications for consequent strengths and limitations of the subject.  相似文献   
74.
In the rail industry worldwide, there has been a search for new solutions, including restructuring, corporatization, and outright privatization, but the complexity of the rail industry offers special problems. In the Workshop we looked in detail at the British, Swedish, German, Australian (New South Wales) and New Zealand experiences, as well as considering more general issues such as cost structures, vertical separation and competitive tendering. Whilst it was agreed that some developments, such as greater contracting out, were clearly beneficial, other developments such as the separation of infrastructure from operations remained of uncertain value until the issues of efficient pricing and slot allocation were resolved.  相似文献   
75.
    
Abstract

Short-term traffic prediction plays an important role in intelligent transport systems. This paper presents a novel two-stage prediction structure using the technique of Singular Spectrum Analysis (SSA) as a data smoothing stage to improve the prediction accuracy. Moreover, a novel prediction method named Grey System Model (GM) is introduced to reduce the dependency on method training and parameter optimisation. To demonstrate the effects of these improvements, this paper compares the prediction accuracies of SSA and non-SSA model structures using both a GM and a more conventional Seasonal Auto-Regressive Integrated Moving Average (SARIMA) prediction model. These methods were calibrated and evaluated using traffic flow data from a corridor in Central London under both normal and incident traffic conditions. The prediction accuracy comparisons show that the SSA method as a data smoothing step before the application of machine learning or statistical prediction methods can improve the final traffic prediction accuracy. In addition, the results indicate that the relatively novel GM method outperforms SARIMA under both normal and incident traffic conditions on urban roads.  相似文献   
76.
    
This paper develops the concept of standard pedestrian equivalent (SPE) factors for converting a mixed pedestrian flow into an equivalent commuter flow. After a comprehensive review of passenger car equivalent (PCE) methodologies, the equal total travel time method is utilised for SPE estimation. A micro-simulation approach is employed for the formulation of the total travel time–flow relationship. Field data collected on walking speed distributions for commuters and older adults in Australia are used as model inputs. An independent samples t-test confirms the significant difference between walking speeds of commuters and older adults. For this paper, a unidirectional flow on flat walkways is initially considered and evaluated across proportions of older people, different flows and different walkway widths. The introduction of older adults significantly increases total travel time especially under congested conditions. Results of this investigation can be used for evaluation or design of pedestrian facilities experiencing similar flow conditions.  相似文献   
77.
    
Valuation of travel time savings is a critical measure in transport infrastructure appraisal, traffic modelling and network performance. It has been recognised for some time that the travel times associated with repeated trips are subject to variation, and hence there is risk embedded in the treatment of expected travel time. In the context of the expected utility framework, we use a nonlinear probability weighting function to accommodate choice made under risk. Although the empirical findings suggest small differences between the value of expected travel time savings (VETTS) in the presence and absence of risk, the mean estimate does make a noticeable difference to time benefits when applied to real projects. By incorporating nonlinear probability weighting, our model reveals that the probabilities associated with specific travel times that are shown to respondents in the choice experiment are transformed, resulting in overweighting of outcomes with low probabilities and underweighting of outcomes with high probabilities. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
78.
    
A method for modeling air carrier departure delays at commercial‐service airports as autoregressive random processes is presented. This method employs the correlation of a priori demand data to significantly reduce prediction error in the optimal least‐squares estimator for additive white noise. The reduction factor of the prediction error is demonstrated to be on the order of 102 over that of the unbiased estimator. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   
79.
    
Abstract

Social capital (SC) describes the advantage individuals and communities can gain from social participation, mutual assistance and trust. The provision of travel options for those who are socially disadvantaged is a major rationale for providing public transport. While there has been recent work on how transport can address social exclusion, SC has been overlooked. This article describes the theoretical basis of SC and suggests ways in which the concept might relate to public transport planning, research and practice. Disadvantaged groups can lack SC, mobility and accessibility. Public transport can provide mobility for this group and, in doing so, provide a greater opportunity to create social networks, trust and reciprocity. Although these concepts are abstract, plausible links are identified between the concepts of enhanced positive social interaction associated with the ‘livable city’ concept and those engendered in SC theory. Public transport by definition involves travelling with others and hence provides opportunities for social interaction while travelling. While a series of possible links between SC and public transport are theorized, it is unlikely these are necessarily strong since other mobility options are available and a range of land‐use and non‐transport alternatives can address social needs. Aspects of the SC concept are already covered by the social mobility and accessibility literature, although it does offer a wider insight into the potential advantages of improving access and mobility for disadvantaged communities. The concept of SC is complex and suffers from a ‘fuzzy’ definition. There is a lack of quantitative primary research associated with measuring SC. Measuring the influence of improved mobility options on SC in disadvantaged communities would be a worthwhile research area. Despite the challenges associated with researching SC, the links between SC and travel present an opportunity to understand how public transport acts to address social disadvantage through the provision of mobility to disadvantaged communities.  相似文献   
80.
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   
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