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221.
222.
The abolition of the national Dock Labour Scheme presented with the oppurtunity radically to transform their cargo handling operations. Port employers have seized this oppurtunity and introduced radical changes to workforce compositions, their skills, work practices, and employee relations. The main factor behind these changes has been the desire of operation to minimize labour costs and maximize labour utilization in order to amintain traffic volume and competitive advantage. The short-term effect has been to improve productivity and profitablity(at least for the major port authorities), but it has also produced iinstablity in employee relations ans may in the long term prove counter productive>  相似文献   
223.
Onboard decision support systems (DSS) are used to increase the operational safety of ships. Ideally, DSS can estimate future ship responses within a time scale of the order of 1–3 h taking into account speed and course changes, assuming stationary sea states. In principle, the calculations depend on a large amount of operational and environmental parameters, which will be known only in the statistical sense. The present paper suggests a procedure to incorporate random variables and associated uncertainties in the calculations of the outcrossing rates that are the basis for risk-based DSS. The procedure is based on parallel system analysis, and the paper derives and describes the main ideas. The concept is illustrated by an example, where the limit state of a non-linear ship response is considered. The results from the parallel system analysis are in agreement with corresponding Monte Carlo simulations. However, the computational speed of the parallel system analysis proved slower than expected.  相似文献   
224.
Travel demand models implicitly assume that people respond to changes in a continuous way. This is in contrast to the physical sciences, where discontinuous response is a common phenomenon and is embodied in such concepts as sub-critical and supercritical states.Recent studies have shown that responses to transport policies differ in degree and kind according to the nature and severity of the stimulus and the types of people affected. Response patterns may be categorised by the extent to which they involve adjustments to spatio-temporal or inter-personal linkages. This paper identifies four response domains, with a further distinction between permissive and forced changes.Most travel demand models are designed to operate within an independent, forced (and to a less extent independent permissive) domain and their forecasts become unreliable when responses lie outside that domain. Conversely, a model designed for a more complex domain is unnecessarily cumbersome where simpler responses apply. This paper describes the types of model which are appropriate for each domain and discusses how the effects of a policy may be assigned to the correct domain(s).  相似文献   
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226.
Traffic incidents are a principal cause of congestion on urban freeways, reducing capacity and creating risks for both involved motorists and incident response personnel. As incident durations increase, the risk of secondary incidents or crashes also becomes problematic. In response to these issues, many road agencies in metropolitan areas have initiated incident management programs aimed at detecting, responding to, and clearing incidents to restore freeways to full capacity as quickly and safely as possible. This study examined those factors that impact the time required by the Michigan Department of Transportation Freeway Courtesy Patrol to clear incidents that occurred on the southeastern Michigan freeway network. These models were developed using traffic flow data, roadway geometry information, and an extensive incident inventory database. A series of parametric hazard duration models were developed, each assuming a different underlying probability distribution for the hazard function. Although each modeling framework provided results that were similar in terms of the direction of factor effects, there was significant variability in terms of the estimated magnitude of these impacts. The generalized F distribution was shown to provide the best fit to the incident clearance time data, and the use of poorer fitting distributions was shown to result in severe over‐estimation or under‐estimation of factor effects. Those factors that were found to impact incident clearance times included the time of day and month when the incident occurred, the geometric and traffic characteristics of the freeway segment, and the characteristics of each incident. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
227.
This paper analyses the past, present and future of the maritime transportation industry in the Kingdom of Saudi Arabia. Saudi Arabian seaborne trade and the shipping capacity are analysed for the past 15 years. Relationships between the declining Saudi shipping capacity and other economic measures are identified. Analysis of the Saudi Arabian maritime transportation is performed with respect to the world carrier fleets and models are developed to determine the theoretical shipping capacity required for transportation of the national seaborne cargo. Forecasts of the future shipping capacity requirement for the Kingdom are also presented. This paper illustrates the general approach for analysing a country's maritime industry and thus could help other researchers in that respect.  相似文献   
228.
International shipping is a significant contributor to Global Greenhouse Gas (GHG) emissions, responsible for approximately 3% of global CO2 emissions. The International Maritime Organization is currently working to establish GHG regulations for international shipping and a cost effectiveness approach has been suggested to determine the required emission reductions from shipping. To achieve emission reductions in a cost effective manner, this study has assessed the cost and reduction potential for present and future abatement measures based on new and unpublished data. The model used captures the world fleet up to 2030, and the analysis includes 25 separate measures. A new integrated modelling approach has been used combining fleet projections with activity-based CO2 emission modelling and projected development of measures for CO2 emission reduction. The world fleet projections up to 2030 are constructed using a fleet growth model that takes into account assumed ship type specific scrapping and new building rates. A baseline trajectory for CO2 emission is then established. The reduction potential from the baseline trajectory and the associated marginal cost levels are calculated for 25 different emission reduction measures. The results are given as marginal abatement cost curves, and as future cost scenarios for reduction of world fleet CO2 emissions. The results show that a scenario in which CO2 emissions are reduced by 33% from baseline in 2030 is achievable at a marginal cost of USD 0 per tonne reduced. At this cost level, emission in 2010 can be reduced by 19% and by 24% in 2020. A scenario with 49% reduction from baseline in 2030 can be achieved at a marginal cost of USD 100 per tonne (27% in 2010 and 35% in 2020). Furthermore, it is evident that further increasing the cost level beyond USD 100 per tonne yield very little in terms of further emission reduction. The results also indicate that stabilising fleet emissions at current levels is obtainable at moderate costs, compensating for fleet growth up to 2030. However, significant reductions beyond current levels seem difficult to achieve. Marginal abatement costs for the major ship types are also calculated, and the results are shown to be relatively homogenous for all major ship types. The presented data and methodology could be very useful for assisting the industry and policymakers in selecting cost effective solutions for reducing GHG emissions from the world fleet.  相似文献   
229.
Some South African cities have initiated public transport transformation projects which, in most cases, ultimately envisage the in toto replacement of paratransit operations with formalised BRT systems. There are two likely outcomes: (1) complex negotiations with existing operators and budget constraints will result in the in toto transformation occurring over an extended period of time; or (2) in toto transformation will simply not occur. In either case, cities will depend, for decades, on a ‘hybrid’ public transport system that combines both formal and paratransit operators. This paper presents a case for policy recognition of hybrid systems, and explores how such systems might best be managed. The following categories of hybrid public transport systems are explored through case studies: (1) transformative processes in which paratransit operators are to form or assimilate into companies to operate new services, but this incorporation has proved difficult to complete and the operational and regulatory frameworks remain unchanged; and (2) transformative processes that, from the outset, anticipated a hybrid system and designed the outcome accordingly. A third category of hybrid transport systems, defined as transformative processes that have been amended following a realisation that in toto transformation is unattainable, is also introduced and discussed. The paper concludes by tentatively drawing lessons for appropriate public transport regulation, particularly with respect to Cape Town's transformation project. It is argued that a review of the current national regulatory framework is required to enable possible project modifications that acknowledge system hybridity. It is suggested that regulatory frameworks that accommodate the likely hybrid nature of public transport system outcomes have greater prospects of success than frameworks that do not. Furthermore, it is argued that contextually appropriate and successful public transport transformation projects do not necessarily require the in toto substitution of incumbent paratransit operators, and that they can be integrated with, and complement, formal services.  相似文献   
230.
Book reviews     
Practice, Politics and Policies—"The Politics of Transport”. By Enid Wistrich. (Harlow, Essex: Longman Group Limited, 1983.) [Pp. 185, with index.] £4·25.

Econometric Analysis and Railway Costing. By W. G. Waters, II and A. D. Woodland. (North Oxford Academic, 1984.) [Pp.132.] £12·95.  相似文献   
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