全文获取类型
收费全文 | 125篇 |
免费 | 0篇 |
专业分类
公路运输 | 15篇 |
综合类 | 33篇 |
水路运输 | 36篇 |
铁路运输 | 30篇 |
综合运输 | 11篇 |
出版年
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 9篇 |
2012年 | 9篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 8篇 |
2008年 | 8篇 |
2007年 | 8篇 |
2006年 | 14篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1994年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有125条查询结果,搜索用时 15 毫秒
101.
102.
Taxis provide essential transport services in urban areas. In the taxi industry, the income level remains a cause of concern for taxi drivers as well as regulators. Mining underlying factors affecting the income level will not only benefit the newcomers and low-income drivers but also assist in developing effective optimization algorithms for taxi operations. This paper intends to disclose the factors affecting incomes along with their quantitative influence by mining over 167 million GPS records from nearly 8000 taxis in Shanghai. We first identify a marked difference in drivers’ incomes and categorize drivers into three income levels accordingly. We next investigate the overall search-delivery process, thereby defining several factors that may affect the income level. We then develop a generalized multi-level ordered logit (GMOL) model to find the significant factors that influence incomes. Finally, we compute the elasticity for those significant factors and present their contributions, as well as challenge some preconceived ideas regarding how to earn high incomes. 相似文献
103.
The primary objective of this study was to evaluate the risks of crashes associated with the freeway traffic flow operating at various levels of service (LOS) and to identify crash-prone traffic conditions for each LOS. The results showed that the traffic flow operating at LOS E had the highest crash potential, followed by LOS F and D. The traffic flow operating at LOS B and A had the lowest crash potential. For LOS A and B, the vehicle platoon and abrupt change in vehicle speeds were major contributing factors to crash occurrences. For LOS C, crash risks were correlated with lane-change maneuvers, speed variation, and small headways in traffic. For LOS D, crash risks increased with an increase in the temporal change in traffic flow variables and the frequency of lane-change maneuvers. For LOS E, crash risks were mainly affected by high traffic volumes and oscillating traffic conditions. For LOS F, crash risks increased with an increase in the standard deviation of flow rate and the frequency of lane-change maneuvers. The findings suggested that the mechanism of crashes were quite different across various LOS. A Bayesian random-parameters logistic regression model was developed to identify crash-prone traffic conditions for various LOS. The proposed model significantly improved the prediction performance as compared to the conventional logistic regression model. 相似文献
104.
从桥梁护栏防撞等级、护栏结构设计、细节优化设计、护栏颜色四个方面入手,利用结构力学、材料力学、色彩心理学等基础学科,结合规范条文要求,提出一种比较实用的设计方法,供护栏设计参考。 相似文献
105.
本文考虑一类阻尼陀螺系统特征值反问题。在假定分析质量矩阵是精确的情况下,运用测量的不完全复模态数据给出了反问题有解的充分必要条件及解的显式表示。在此基础上研究了一个逼近问题,得到了Frobenius范数意义下的最优矩阵。 相似文献
106.
抗蛇行减振器在高速列车上的应用 总被引:3,自引:1,他引:2
讨论了抗蛇行减振器在高速列车上的应用,分析了抗蛇行减振器的特性,给出了减振器阻尼系数和卸荷的范围,特别提到了减振器的串联刚度问题。对抗蛇行减振器的安装位置也提出了建议,并阐述了抗蛇行减振器的安高度对车体结构弯曲振动的影响。 相似文献
107.
对高职院校进行科学定位,理清发展思路,确立办学指导思想、发展目标、人才培养模式、办学形式、服务面向等是一项十分重要的工作。本文以浙江交通职业技术学院为例,在定位及其相关概念的基础上,研究了学院的类型和层次定位、总体目标定位、人才培养和层次定位、专业定位、办学思路和发展目标定位、科研方向定位和服务面向定位。 相似文献
108.
芮国华 《辽宁省交通高等专科学校学报》2012,14(4):38-40
无论国产或进口液压履带式起重机在使用一段时间以后,均不同程度地出现行走不同步的故障,此故障加速了履带板、驱动轮的磨损。本文详述了行走不同步故障的现象、原因、以及快速诊断与排除方法。 相似文献
109.
110.
Numerical study of ice-induced loads on ship hulls 总被引:1,自引:0,他引:1
A numerical model is introduced in this paper to investigate both global and local ice loads on ship hulls. This model is partly based on empirical data, by which the observed phenomena of continuous icebreaking can be well reproduced. In the simulation of a full-scale icebreaking trial, the interdependence between the ice load and the ship’s motion is considered, and the three degree-of-freedom rigid body equations of surge, sway and yaw are solved by numerical integration. The variations in the level ice thickness and in the strength properties of ice can also be taken into account. The simulated ice loads on ship hulls are discussed through two case studies, in which the ship’s performance, the statistics of ice-induced frame loads, and the spatial distribution of ice loads around the hull are analyzed and compared with field measurements. As far as we know the present paper is the first to integrate all the features above. It is hoped that further studies on this numerical model can supplement the field and laboratory measurements in establishing a design basis for the ice-going ships especially for ships navigating in the first-year ice. 相似文献