全文获取类型
收费全文 | 1223篇 |
免费 | 14篇 |
专业分类
公路运输 | 638篇 |
综合类 | 25篇 |
水路运输 | 251篇 |
铁路运输 | 29篇 |
综合运输 | 294篇 |
出版年
2024年 | 2篇 |
2023年 | 19篇 |
2022年 | 46篇 |
2021年 | 7篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 99篇 |
2017年 | 72篇 |
2016年 | 156篇 |
2015年 | 11篇 |
2014年 | 59篇 |
2013年 | 46篇 |
2012年 | 84篇 |
2011年 | 163篇 |
2010年 | 152篇 |
2009年 | 64篇 |
2008年 | 100篇 |
2007年 | 52篇 |
2006年 | 11篇 |
2005年 | 12篇 |
2004年 | 15篇 |
2003年 | 10篇 |
2002年 | 5篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有1237条查询结果,搜索用时 886 毫秒
141.
Konstantinos G. Zografos Konstantinos N. Androutsopoulos Teemu Sihvola 《Transportation》2008,35(6):777-795
Flexible transport services include a wide range of demand responsive transport systems that provide non-conventional passenger
and freight transportation services. Several alternative business models varying according to the local market conditions,
the socio-economic, legal, and institutional framework may be developed for the provision of Flexible Transport Systems (FTS).
The objective of this paper is twofold: first to present an integrated methodological framework for developing and assessing
alternative FTS business models and second to demonstrate its applicability to a case study regarding the prioritization of
alternative FTS business models for the provision of flexible passenger transport services in Helsinki.
相似文献
Teemu SihvolaEmail: |
142.
Athanasios A. Pallis 《WMU Journal of Maritime Affairs》2007,6(1):3-20
Throughout Europe, a number of maritime interests have re-targeted their lobbying structures and strategies aiming to influence
the development of the maritime related European Union (EU) policies. The paper examines these maritime interests’ mobilisation
in the making of the Common EU Maritime Transport Policy (CMTP). First, it provides a review of the role of these interest
groups and the implications of the observed collective interests’ representation. Then, with the contribution a data-set of
replies to a questionnaire distributed to all the interest groups that are involved in EU maritime affairs, the paper analyses
the variety of interest groups representing the maritime sector in EU affairs. The focus is on the structures (i.e. membership
numbers and types, location, internal structures, budget) and the lobbying practices of the 37 identified EU level maritime
related organisations. The paper also presents an evaluation of the most positive and most negative parameters of the ‘EU
environment’ and the ‘economic environment’ that assist, or undermine, the governability cohesiveness of this collective action.
This study provides information on whether and under what conditions maritime interests are able to form comprehensive EU-level
organisations capable of representing their members and their interests in the EU policy making process 相似文献
143.
144.
145.
Chang Doo Jang Jong Jin Jung Alexander A. Korobkin 《Journal of Marine Science and Technology》2007,12(2):95-101
This article describes an estimation method for the hull girder response of a ship due to springing. The linear and nonlinear
springing effects on the hull girder are evaluated. Previous studies on the springing response focused mainly on the symmetric
response, or vertical response. In this article, however, the springing analysis is extended to asymmetric responses, or horizontal
and torsional responses. The Timoshenko beam model was used to calculate the hull girder response and the quadratic strip
method was employed to calculate hydrodynamic forces and moments on the hull. To remove irregular frequencies, a rigid lid
was adopted on the hull free surface level and hydrodynamic coefficients were interpolated for asymptotic values. Applications
to two ships for the symmetric and asymmetric responses were carried out and the effect of springing responses is also discussed. 相似文献
146.
147.
This paper presents a system dynamics approach to simultaneous land use/transportation system performance modeling. A model is designed based on the causality functions and feedback loop structure between a large number of physical, socioeconomic, and policy variables. The model consists of 7 sub‐models: population, migration of population, household, job growth‐employment‐land availability, housing development, travel demand, and traffic congestion level. The model is formulated in DYNAMO simulation language, and tested on a data set from Montgomery County, MD. In Part I: Methodology, the overall approach and the structure of the model system is discussed and the causal‐loop diagrams and major equations are presented. In Part II: Application, the model is calibrated and tested with data from Montgomery County, MD. Least square method and overall system behavior are used to estimate the model parameters. The model is fitted with the 1970–80 data and validated with the 1980–1990 data. Robustness and sensitivities with respect to input parameters such as birth rate or regional economy growth are analyzed. The model performance as a policy analysis tool is examined by predicting the year by year impacts of highway capacity expansion on land use and transportation system performance. While this is a first attempt in using dynamic system simulation modeling in simultaneous treatment of land use and transportation system interactions, and model development and application are limited due to data availability, the results indicate that the proposed method is a promising approach in dealing with complex urban land use/transportation modeling. 相似文献
148.
J. Y. Wong R. R. Guntur 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1978,7(1):25-47
It is known that loss of directional stability during braking occurs in many road accidents involving tractor-semitrailers. To minimize the undesired directional response, the correct order of locking of the wheels is of importance and should receive greater attention. This paper examines the effects of operational and design parameters on the sequence of locking of the wheels of tractor-semitrailers. The way in which the correct locking sequence may be achieved is also discussed in detail. 相似文献
149.
H. P. Y. Hitch 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1981,10(4):319-332
The state-of-the-art in analysing a number of ground manoeuvring processes on aircraft is described. The mathematical models are as good as the data supplied to them. 相似文献
150.
G. S. Jung Y. H. Sung B. C. Choi C. W. Lee M. T. Lim 《International Journal of Automotive Technology》2012,13(3):347-353
Although premixed charge compression ignition (PCCI) combustion engines are praised for potentially high efficiency and clean
exhaust, experimental engines built to date emit more hydrocarbons (HCs) and carbon monoxide (CO) than the conventional machines.
These compounds are not only strictly controlled components of the exhaust gas of road vehicles but are also an energy loss
indicator. The prime objective of this study was to investigate the major sources of the HCs formed in the combustion chamber
of an experimental PCCI engine in order to suggest some effective technologies for HC reduction. In this study, to explore
the dominant sources of HC emissions in both operation modes, a single cylinder engine was prepared such that it could operate
using either conventional diesel combustion or PCCI combustion. Specifically, the contributions of the top-ring crevice volume
in the combustion chamber and the bulk quenching of the lean mixture were investigated. To understand the influence of the
shape and magnitude of the crevice on HC emissions, the engine was operated with 12 specially prepared pistons with different
top-ring crevices installed one after another. The engine emitted proportionally more HCs as the depth of the crevice increased
as long as the width remained narrower than the prevailing quench distance. The top-ring-crevice-originated exhaust HCs comprised
approximately 31% of the total HC emissions in the baseline condition. In a series of tests to estimate the effects of bulk
quench on exhaust HC emissions, intake air was heated from 300K to 400K in steps of 25K. With the intake air heated, HC and
CO emissions decreased with a gradually diminishing rate to zero at 375K. In conclusion, the most dominant sources of HC emissions
in PCCI engines were the crevice volumes in the combustion chamber and the bulk quenching of the lean mixtures. The key methods
for reducing HC emissions in PCCI engines are minimizing crevice volume in the combustion chamber and maximizing intake air
temperature allowed based on the permissible NOx level. 相似文献