全文获取类型
收费全文 | 1234篇 |
免费 | 16篇 |
专业分类
公路运输 | 563篇 |
综合类 | 45篇 |
水路运输 | 309篇 |
铁路运输 | 25篇 |
综合运输 | 308篇 |
出版年
2023年 | 9篇 |
2022年 | 20篇 |
2021年 | 9篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 31篇 |
2017年 | 39篇 |
2016年 | 78篇 |
2015年 | 17篇 |
2014年 | 67篇 |
2013年 | 190篇 |
2012年 | 66篇 |
2011年 | 77篇 |
2010年 | 73篇 |
2009年 | 57篇 |
2008年 | 77篇 |
2007年 | 35篇 |
2006年 | 30篇 |
2005年 | 24篇 |
2004年 | 20篇 |
2003年 | 10篇 |
2002年 | 13篇 |
2001年 | 17篇 |
2000年 | 29篇 |
1999年 | 15篇 |
1998年 | 14篇 |
1997年 | 17篇 |
1996年 | 22篇 |
1995年 | 24篇 |
1994年 | 9篇 |
1993年 | 16篇 |
1992年 | 13篇 |
1991年 | 11篇 |
1990年 | 4篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 10篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1973年 | 4篇 |
排序方式: 共有1250条查询结果,搜索用时 15 毫秒
91.
This papers examines the different choices of High Speed Craft (HSC) hull design available and briefly looks at the advantages and disadvantages of each hull form. The trends in various design aspects of HSC such as speed, capacity and size are studied. An investigation on the HSC development is conducted and the future of HSC in the UK is studied. A study onboard an HSC with the aim of trying to determine what passengers think of HSC and why they travel by them is also conducted. Finally, an analysis of the possible market for HSC is carried out. 相似文献
92.
S. R. C. Wanhill 《Maritime Policy and Management》2013,40(1):48-55
The correct number of berths that a port should provide is solved by a model which minimizes the total port usage cost in terms of the costs of berth provision and the costs accruing to ships from time spent in the port. This model is then applied to Mina Zayed in the Arabian Gulf as an aid to future planning, and from different sets of cargo forecasts an optimal stategy is derived using a game-theoretic approach. 相似文献
93.
Compression ratio (CR) is a design parameter with highest influence on efficiency, emission and engine characteristics. In conventional internal combustion (IC) engines, the compression ratio is fixed and their performance is, therefore, a compromise between conflicting requirements. One fundamental problem is that drive units in the vehicles must successfully operate at variable speed and loads and in different ambient conditions. If a diesel engine has a fixed CR, a minimal value must be chosen that can achieve a reliable self-ignition when starting the engine in cold start conditions. In diesel engines, variable compression ratio (VCR) provides control of peak cylinder pressure, improves cold start ability and low load operation, enabling the multi-fuel capability, increase of fuel economy and reduction of emissions. By application of VCR and other mechanisms, the optimal regime fields are extended to the prime requirements: consumption, power, emission, noise, etc., and/or the possibility of the engine to operate with different fuels is extended. An experimental Diesel engine has been developed at the Faculty of Engineering, University of Kragujevac. The changes of CR are realized by changing the piston chamber diameter. Detailed engine tests were performed at the Laboratory for IC engines. Special attention has been given to decrease of fuel consumption and exhaust emissions. An optimal field of CR variation has been determined depending on the given objectives: minimal fuel consumption, minimal nitric oxides, and particulate matter emissions, etc. 相似文献
94.
It is important to know the effect of the aerodynamic forces and moments on driving stability because it is responsible for the excitation and influences the response of the vehicle. The purpose of this paper is to study the effect of rear slant angle of a surface vehicle on crosswind sensitivity for stability analysis. The vehicle mathematical model used to conduct a dynamic simulation was based on a simple reduced order lateral dynamics of sideslip and yaw rate motion coupled with aerodynamics model. The intention here is to compare the effect of rear slant angles response to crosswind and to rank the crosswind sensitivity ratings. The aerodynamic loads are defined as the function of the aerodynamic derivatives from the static wind tunnel tests. Result shows a 20° rear slant angle demonstrates the highest rating of crosswind sensitivity, while zero degree slant exhibits the least. 相似文献
95.
96.
The purpose of this study is first to find out whether quarterly averages of non-OPEC (Organization of the Petroleum Exporting Countries) supply follow a seasonal pattern. If that is mathematically established, then, second, it is attempted to estimate the best seasonal factors to decompose the forecast yearly average into quarterly averages. A set of historical data consisting of quarterly supply averages of individual countries, regional subtotals and the aggregate non-OPEC supply for the period 1973-2002 forms the basis of the analysis. The study applies Fourier analysis to quarterly supply series to test for seasonality, and provides estimates of seasonal factors for the years 2000-2002 by applying the so-called X-11 decomposition method to the historical annual averages. The accuracy of the results of the application of X-11 is then tested. It is demonstrated that the combination of the Fourier and X-11 methods provides mostly acceptable and in some cases, such as that of China, impressively accurate forecast quarterly supply averages. 相似文献
97.
We report here on how we adapted Interactive Stated Response Methods to use in a self-completion survey of 454 California households to measure the market for electric vehicles in California. Electric vehicles are a novel product and have many features unfamiliar to consumers, in particular their home recharging capability and limited range. Reflexive techniques were designed to draw households into a deeper exploration of the lifestyle implications of electric vehicles than can be done in more typical self-completion surveys, and to stimulate key decision processes previously observed in detailed gaming interviews with 51 households. Reflexive self-completion techniques provide a middle course between typical large sample quantitative surveys and small sample, detailed gaming interviews. One of the benefits of the more intensive techniques was that participants reported finding the surveys interesting and return rates were high for a self-completion approach – over sixty percent. We review previous transportation and sociological methods which inspired our design, describe the design goals and features of our research, and summarize research results pertinent to testing the validity of our approach. 相似文献
98.
Validation of a schedule‐based capacity restraint transit assignment model for a large‐scale network
This paper describes the application of a capacity restraint trip assignment algorithm to a real, large‐scale transit network and the validation of the results. Unlike the conventional frequency‐based approach, the network formulation of the proposed model is dynamic and schedule‐based. Transit vehicles are assumed to operate to a set of pre‐determined schedules. Passengers are assumed to select paths based on a generalized cost function including in‐vehicle and out‐of‐vehicle time and line change penalty. The time‐varying passenger demand is loaded onto the network by a time increment simulation method, which ensures that the capacity restraint of each vehicle during passenger boarding is strictly observed. The optimal‐path and path‐loading algorithms are applied iteratively by the method of successive averages until the network converges to the predictive dynamic user equilibrium. The Hong Kong Mass Transit Railway network is used to validate the model results. The potential applications of the model are also discussed. 相似文献
99.
Container ports serve as important conduits to facilitate the efficient flow of containerized cargo. As part of value-driven chain systems that intersect between hinterlands, efficiency gains that are generated within the container port will have a direct impact on the competitive advantage of its users and affect the economic potential of both the origin and destination hinterlands. As such, the paper proposes the usage of indifference analysis propounded in microeconomic theory as a useful means to examine inter-container port competition and complementarity. The framework presented can also be combined with Porter's 'Diamond' model in order for inter-container port demand relationships to be quantified, measured and analysed in an holistic manner. Apart from analysing inter-port relationships from the standpoint of container ports, the framework can also be used to analyse inter-port relationships from the perspective of other key players in the value-driven chain system and modified accordingly to incorporate various indicators that are deemed to be relevant to these parties. 相似文献
100.
A chance-constrained based stochastic dynamic traffic assignment model: Analysis, formulation and solution algorithms 总被引:1,自引:0,他引:1
S. Travis Waller Athanasios K. Ziliaskopoulos 《Transportation Research Part C: Emerging Technologies》2006,14(6):418-427
This paper is concerned with the system optimum-dynamic traffic assignment (SO-DTA) problem when the time-dependent demands are random variables with known probability distributions. The model is a stochastic extension of a deterministic linear programming formulation for SO-DTA introduced by Ziliaskopoulos (Ziliaskopoulos, A.K., 2000. A linear programming model for the single destination system optimum dynamic traffic assignment problem, Transportation Science, 34, 1–12). The proposed formulation is chance-constrained based and we demonstrate that it provides a robust SO solution with a user specified level of reliability. The model provides numerous insights and can be a useful tool in producing robust control and management strategies that account for uncertainty in applications where SO-DTA is relevant (e.g. evacuation modeling, computing alternate routes around freeway incidents and establishing lower bounds on network performance). 相似文献