全文获取类型
收费全文 | 164篇 |
免费 | 2篇 |
专业分类
公路运输 | 5篇 |
综合类 | 21篇 |
水路运输 | 64篇 |
铁路运输 | 3篇 |
综合运输 | 73篇 |
出版年
2022年 | 1篇 |
2021年 | 9篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 4篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 2篇 |
2013年 | 9篇 |
2012年 | 16篇 |
2011年 | 10篇 |
2010年 | 2篇 |
2009年 | 7篇 |
2008年 | 3篇 |
2006年 | 1篇 |
2005年 | 28篇 |
2004年 | 27篇 |
2003年 | 8篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有166条查询结果,搜索用时 406 毫秒
71.
Ülkü Alver ?ahin Burcu OnatBaktygul Stakeeva Tuba CeranP?nar Karim 《Transportation Research Part D: Transport and Environment》2012,17(1):48-53
In this study, PM10 concentrations, as well as the size distributions of Fe-containing and Cu-containing particles are measured in six subway stations in Istanbul. The average daily PM10 concentrations are found to vary considerably. They were also found to be significantly higher than the levels found at urban air quality stations. Further, the relative abundance of Fe-containing particles among the particles of size >2.1 μm collected in the metro stations is 3.5-8 times higher than in the in the Istanbul atmosphere. 相似文献
72.
This article presents the results of a study exploring travellers’ preferences for middle-distance travel using Q-methodology.
Respondents rank-ordered 42 opinion statements regarding travel choice and motivations for travel in general and for car and
public transport as alternative travel modes. By-person factor analysis revealed four distinct preference segments for middle-distance
travel: (1) choice travellers with a preference for public transport, (2) deliberate-choice travellers, (3) choice travellers
with car as dominant alternative, and (4) car-dependent travellers. These preference segments differ in terms of the levels
of involvement and cognitive effort in travel decision making, the travel consideration-set and underlying motivations. The
study showed that for most people there is more to travel than getting from point A to point B, and that there is considerable
heterogeneity in middle-distance travel preferences. Policy implications for reducing the need for travel and promoting a
modal shift from car to other travel modes are discussed. 相似文献
73.
74.
Submerged arc welding (SAW) is advantageous for joining high thickness materials in large structure due to high material deposition rate. The non-uniform heating and cooling generates the thermal stresses and subsequently the residual stresses and distortion. The longitudinal and transverse residual stresses and angular distortion are generally measured in large panel structure of submerged arc welded fillet joints. Hence, the objective of this present work is to quantify the amount of residual stress and distortion in and around the weld joint due to positioning of stiffeners tack. The tacking sequence influences the level of residual stress and proper controlling of tacking sequences is required to minimize the stress. In present study, an elasto-plastic material behavior is considered to develop the thermo mechanical model which predicts the residual stress and angular distortion with varying tacking sequences. The simulated result reveals that the tacking sequence heavily influences the residual stress and deformation pattern of the single sided fillet joint. The finite element based numerical model is calibrated by comparing the experimental data from published literature. Henceforth, the angular distortions are measured from an in-house developed experimental set-up. A fair agreement between the predicted and experimental results indicates the robustness of the developed numerical model. However, the most significant conclusion from present study states that tack weld position should be placed opposite to the fillet weld side to minimize the residual stress. 相似文献
75.
Subsea flowline jumper (FJ) is basic connection component for the wet oil tree, the subsea pipeline and the riser base, playing an irreplaceable role in the subsea production system. During the installation of FJ, collisions often happen between FJ and other equipment, which may cause serious damage. Besides, as the operating water depth increases, the demand for the installation equipments like the crane and winch will increase. The research of deepwater FJ installation in China is still in the primary stage, so an installation method for deepwater FJ is proposed in this paper. Finite element models of a typical M-shape FJ installation system were built to simulate the installation procedures. Analysis results showed that the installation steps designed for the FJ are feasible and valid for deepwater FJ. In order to ensure the safety of the installation process, the collision-sensitive analysis for the FJ was conducted, and results show that it is necessary to set the pick up speed at a proper value, in order to avoid collision in installation process. Besides, the mechanical characteristics of FJ during the installation were investigated under a range of environmental conditions and it was found that the maximum stress of the FJ always happens at its central position. The basic requirements for the installation equipment were also obtained through the analysis of the main installation steps. 相似文献
76.
Abstract This paper presents an examination of the empirical merits of a set of spatial interaction indices for measuring hierarchical differentiation (i.e. dominance and connectivity) in a spatial network. To allow for the comparison of the degree of hierarchical differentiation in networks with different numbers of nodes/links, we propose to normalize the ratio between the real measures and the corresponding values for a rank size distribution in order to obtain readily interpretable measures of hierarchical differentiation. When applied to data on air passenger flows within Europe, the normalized indices, interpreted together, appear to give a good idea of the tendency toward hierarchical differentiation. The potential usefulness of this analytical framework is discussed in the context of studies on (transnational) inter-city relations and empirical assessments of changes in the spatial configuration of airline networks. 相似文献
77.
2013年浙江省各市开展全面治堵工作,其中提高公共交通的服务水平是交通治堵的重点工作,也是城市交通可持续发展的必经之路。公交服务水平的提高不仅追求量的发展,还要保证质的提升,而对公交线路进行提速就是提升公交服务品质的途径之一。本文在城市交通治堵的大环境下,利用治堵的压力和动力,借机调动大量资源,从公交系统内和公交系统外全面、系统、科学地对温州运量最大的前20条线路进行提速。通过方案的逐步落实,3条提速线路效果明显,城市交通也得到进一步改善。 相似文献
78.
The importance of being early 总被引:1,自引:0,他引:1
Pavithra?ParthasarathiEmail author Anupam?Srivastava Nikolas?Geroliminis David?Levinson 《Transportation》2011,38(2):227-247
This research quantifies the relationship between the cost of earliness and lateness by empirically observing commute trips
from two different sources. The first empirical analysis uses individual level travel survey data from six metropolitan regions
while the second analysis uses traffic data from the Twin Cities freeway network. The analysis conducted in this research
provides a method to estimate the ratio of the costs of earliness to lateness for different datasets. This can be a useful
tool for traffic engineers and planners, to assist them in the development and implementation of improved control strategies
for congested cities. The results also corroborates the hypothesis of earliness being less expensive than lateness and show
that the finding holds steady over time and across different regions and levels. 相似文献
79.
80.
A serious interest in high speed train has been increasing all over the world. However, recent experiences in Asian countries
show that high speed rail projects are not financially viable even in areas seemingly favorable to rail operations. Considering
the existing intensive highway and airline network, putting public subsidies to high speed rail projects are barely justifiable
from a purely economic point of view. What is required of any government which contemplates high speed rail construction as
a policy option is to show taxpayers the cost/revenues difference between constructing a high speed rail line and expanding
a capacity of other means, before proceeding. 相似文献