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721.
This paper presents an application of shallow water theory to describe the motion of floodwater inside a rolling ship in damage
condition. The time domain theoretical approach to the coupled problems of ship and water inside compartment motions is briefly
described, including the method used to solve for the water motion characteristics and forces exerted on the ship. This approach
is applied to the study of the behaviour of a passenger Ro–Ro ship in regular beam seas and numerical results are given for
the intact and damaged conditions. Comparison is made with experimental results. For the damaged condition, the characteristics
of the floodwater motion are studied in the time domain for a number of different wave frequencies. The shape of the free-surface
and phase of water motion in relation to the ship roll motion are shown for several wave frequencies. The dynamic floodwater
roll moment is also shown and compared with the static roll moment (flat horizontal free surface), allowing the conclusion
that the dynamic roll moment is much larger than the static roll moment, for high wave frequencies, and is in phase opposition
in relation to the roll motion. 相似文献
722.
Margarida C. Coelho H. Christopher Frey Nagui M. Rouphail Haibo Zhai Luc Pelkmans 《Transportation Research Part D: Transport and Environment》2009,14(2):91-99
This paper assess whether a real-world second-by-second methodology that integrates vehicle activity and emissions rates for light-duty gasoline vehicles can be extended to diesel vehicles. Secondly it compares fuel use and emission rates between gasoline and diesel light-duty vehicles. To evaluate the methodology, real-world field data from two light-duty diesel vehicles are used. Vehicle specific power, a function of vehicle speed, acceleration, and road grade, is evaluated with respect to ability to explain variation in emissions rates. Vehicle specific power has been used previously to define activity-based modes and to quantify variation in fuel use and emission rates of gasoline vehicles taking into account idle, acceleration, cruise, and deceleration. The fuel use and emission rates for light-duty diesel vehicles can also be explained using vehicle specific power -based modes. Thus, the methodology enables direct comparisons for different vehicle fuels and technologies. Furthermore, the method can be used to estimate average fuel use and emission rates for a wide variety of driving cycles. 相似文献
723.
724.
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
725.
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
726.
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
727.
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
728.
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
729.
Jarir Dajani F. C. Flury David Bayliss John Friedmann Peter J. O'Keeffe 《Transportation》1973,1(4):461-474
730.
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