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771.
772.
S. C. Wong 《Transportation Research Part B: Methodological》1999,33(8):123
In Bell M.G.H. (1995. Transportation Research B 29, 287–295), a new logit assignment formulation was developed, which considered all possible paths in the network while still retaining the absence of a need for path enumeration. In his formulation, it presumes that the sum of a geometric series of the weights matrix always converges and hence can be computed as the inversion of a matrix. In this paper, we investigate the convergence properties of this geometric series by means of an eigensystem interpretation which states that the series converges if and only if all the eigenvalues associated with the weights matrix fall into the unit circle in a complex plane. It is found that the geometric series converges unconditionally for acyclic networks, but not necessarily does so for general networks. 相似文献
773.
Traditionally, many economists have examined the models and economics of urban taxi services under various types of regulation such as entry restriction and price control in an aggregate way. Only recently have we modeled urban taxi services in a network context. A realistic method has been proposed to describe vacant and occupied taxi movements in a road network and taxi drivers' search behavior for customers. A few extensions have been made to deal with demand elasticity and congestion effects together with development of efficient solution algorithms. Calibration and validation of the network taxi service models have been conducted towards their practical applications. This paper presents an overview of the research that has been carried out by the authors to develop network equilibrium models and solution algorithms for urban taxi services, and offers perspectives for future researches. 相似文献
774.
Among disaggregate vehicle ownership models, which model the number and/or type of vehicles owned at the household level,
one can distinguish holdings models, which deal with the (optimal) household fleet at a single point in time, and transactions
models. The latter type of model explains changes to the household fleet, such as replacement and disposal. The paper describes
previous attempts at such dynamic models and sketches how a vehicle transactions model could look (as an example we discuss
an application to The Netherlands). This includes discussions of transaction probabilities, two-stage budgeting, introducing
vehicle quality in the utility functions, and the envisaged model structure and data it could use. 相似文献
775.
S. Bazin C. Beckerich C. Blanquart M. Delaplace L. Vandenbossche 《Recherche - Transports - Sécurité》2011,27(3):215-238
Many high-speed rail (HSR) projects exist in Europe and elsewhere in the world and generate many expectations: economic development, location of new firms and new population, development of tourism, effect on real estate. But these expectations are not always fulfilled. For academic researchers, the myth of the existence of a linear causality between transport infrastructures and spatial, social and economic transformations, according to which automatic effects will occur, has been challenged for a long time. But sometimes, new economic dynamism can be observed. The aim of this paper is to present a review of academic and non-academic literature in order to understand why there is a gap between the academic literature and the regional stakeholders’ expectations. 相似文献
776.
Pablo Jensen Jean-Baptiste Rouquier Nicolas Ovtracht Céline Robardet 《Transportation Research Part D: Transport and Environment》2010,15(8):522-524
Data gathered relating to the Lyon’s shared bicycling system, Vélo’v, is used to analyze 11.6 millions bicycle trips in the city. The data show that bicycles now compete with the car in terms of speed in downtown Lyon. It also provides information on cycle flows that can be of use in the planning of dedicated bicycle lanes and other facilities. 相似文献
777.
Jarir Dajani F. C. Flury David Bayliss John Friedmann Peter J. O'Keeffe 《Transportation》1973,1(4):461-474
778.
Among the general problematic of the HEV power trains, the most critical point is the determination of the power-split ratio
between the mechanical and the electrical paths, known as the energy management strategy (EMS). Many EMS are proposed in the
literature, and can be grouped in two categories: the local optimization EMS and the global optimization EMS. The local optimization
category corresponds to the EMS based on human expertise and the knowledge of the power train components efficiency maps.
Thus, the local optimization EMS manages the power train operations by referring to predefined rules. The drawback of such
strategies is that it brings an instantaneous fuel consumption optimization, and does not fully optimize the fuel consumption
over the whole trip. Therefore, additional fuel savings are still possible. This paper presents an overall optimized predictive
EMS for the Toyota Hybrid System (THS-II) power train of the Prius. The proposed EMS is based on Dynamic Programming (DP),
where the prior knowledge of the route is required in order to predetermine the power-split ratio and optimize the fuel consumption
for the whole predicted route. The DP EMS proposed for the THS-II power train is designed with a very short computation time,
intended to be implemented in real-time applications. The potential of this DP-controller in reducing fuel consumption on
regulatory cycles are computed and compared to a rule-based controller and to the Prius published fuel consumption results.
Finally, the fuel reduction enhancements of the DP-controller are computed for real road tests achieved on a MY06 Prius in
Ile-de-France, by comparing to the associated observed consumption measurements. 相似文献
779.
This paper considers the physical processes of corrosion that occur in bulk carriers. Three main types of corrosive environments are identified within a bulk carrier, namely, immersion in seawater, exposure to an enclosed atmosphere, and exposure to porous media. Fundamental variables influencing corrosion in each environment of the cargo hold region, ballast tanks and void spaces are identified. These serve to identify operational parameters that affect bulk carrier corrosion. It is proposed that such parameters can be used to obtain corrosion rate databases representative of vessel operation. 相似文献
780.
Inspite of the inherent weaknesses in aggregate demand models, they continue to be used in everyday applications, especially in developing countries. The largely data intensive disaggregate model preclude its application in many cases. This paper attempts the formulation and calibration of an aggregate total demand model for estimating inter-district passenger travel by public transport in Sri Lanka. In its process, an investigation is made of the common problems in the aggregate approach while examining possible remedial measures to improve the accuracy and (hence) the usability of the aggregate model. It is argued that commonly used variables and functional forms are inappropriate for making accurate estimates in developing countries. Consequently, the model calibration is shown to incorporate variables representing urbanisation, under-development, transfers, a mode-abstract cost function and intrinsic features. The necessity for functional form for each variable to be based on behavioral assumptions that are tested using the Box-Cox transformation for ensuring the best fit of the data is also observed. Although, the model form was calibrated for Sri Lanka, the model is generalised in order for its applications to other countries as well as, both, inter-district and intercity travel demand estimation. 相似文献