全文获取类型
收费全文 | 2403篇 |
免费 | 153篇 |
专业分类
公路运输 | 688篇 |
综合类 | 766篇 |
水路运输 | 612篇 |
铁路运输 | 367篇 |
综合运输 | 123篇 |
出版年
2024年 | 10篇 |
2023年 | 18篇 |
2022年 | 75篇 |
2021年 | 136篇 |
2020年 | 75篇 |
2019年 | 50篇 |
2018年 | 39篇 |
2017年 | 39篇 |
2016年 | 42篇 |
2015年 | 98篇 |
2014年 | 121篇 |
2013年 | 140篇 |
2012年 | 156篇 |
2011年 | 203篇 |
2010年 | 211篇 |
2009年 | 204篇 |
2008年 | 200篇 |
2007年 | 240篇 |
2006年 | 184篇 |
2005年 | 135篇 |
2004年 | 54篇 |
2003年 | 32篇 |
2002年 | 17篇 |
2001年 | 22篇 |
2000年 | 25篇 |
1999年 | 13篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1991年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有2556条查询结果,搜索用时 171 毫秒
81.
82.
Users’ acceptability is considered one of the key drivers for the successful implementation of transport policy measures. This is especially crucial in the case of toll roads since they are financed through drivers’ contributions. Previous literature in this field has mainly focused on measuring users’ attitudes towards urban congestion pricing strategies. However limited research has been developed concerning interurban toll roads. Previous research shows that socioeconomic variables are not conclusive to explain users’ perceptions towards tolls. By contrast, other drivers such as regional differences seem to play a more important role, especially when charging conditions within the same nation greatly vary across regions. This paper analyzes regional differences in users’ attitudes within an asymmetrical distribution of the toll road network across regions. Based on a nationwide survey conducted to road users in interurban toll roads in Spain, we develop both a binomial logit and a censored regression (tobit) model to explore drivers’ perceptions and willingness to pay. The research concludes that users from regions with a more extensive tolled network generally show a more negative attitude towards charges, but not necessarily a lower willingness to pay. The paper also points out that an asymmetrical distribution of toll roads across regions may result in negative perceptions among those users perceiving to be unfairly treated when compared to citizens in other regions. 相似文献
83.
Users’ loyalty to public transit service is fundamental to promote its popularity in the transportation market. A four-step analytical framework is advanced to investigate the importance of service attributes that heterogeneous transit user segments place on their public transit service loyalty, measured in terms of overall satisfaction and re-use intention. Critical service attributes perceived by transit users that are relevant for loyalty enhancement are explicitly determined, which vary between user segments. It is suggested that the design of strategies aimed to promote the use of public transit by increasing user loyalty towards transit service be targeted at specific attributes that contribute most to loyalty and specific user segments whose original loyalty level is significantly different to others. 相似文献
84.
85.
86.
一种计算吊舱与螺旋桨相互干扰的新方法(英文) 总被引:1,自引:0,他引:1
为了计算吊舱推进器的非定常水动力性能,建立了用诱导速度势处理吊舱和螺旋桨非定常相互干扰的方法,并和用诱导速度处理两者相互干扰的方法作了对比分析.讨论了两种方法的数值计算中为了避免奇异性而对一些参数的设定方法.经过用两种方法对均匀来流和非均匀来流条件下水动力性能的计算比较,发现两种方法的计算结果很接近,并与模型试验结果吻合得很好,但用诱导速度势的方法编程工作量较诱导速度方法少,而且还可节省大量的计算时间和存储空间,是一种计算吊舱推进器和其他组合推进器水动力性能相对简单而且有效的方法. 相似文献
87.
文章对双桨船脉动压力进行了计算,计算时考虑了左右螺旋桨之间的相位差对脉动压力计算的影响,结果证明汁算双桨船的脉动压力时,相位差的影响不能忽略,不同的相位差得到的计算结果有明显差别,越靠近船体内侧,相位差引起的幅值变化越大.相位差的影响还同双桨的距离有关系,双桨的距离越近,相位差的影响越显著,随着双桨距离加大,相位差的影响减小.这可以部分解释脉动压力模型实验和实船测试中的一些现象,同时也提醒试验人员在进行双桨船脉动压力试验时,要注意双桨相位差的影响. 相似文献
88.
89.
90.