全文获取类型
收费全文 | 27633篇 |
免费 | 2489篇 |
专业分类
公路运输 | 6690篇 |
综合类 | 7099篇 |
水路运输 | 10852篇 |
铁路运输 | 4721篇 |
综合运输 | 760篇 |
出版年
2024年 | 18篇 |
2023年 | 69篇 |
2022年 | 490篇 |
2021年 | 661篇 |
2020年 | 913篇 |
2019年 | 961篇 |
2018年 | 846篇 |
2017年 | 805篇 |
2016年 | 886篇 |
2015年 | 1263篇 |
2014年 | 1381篇 |
2013年 | 1897篇 |
2012年 | 1891篇 |
2011年 | 1792篇 |
2010年 | 1865篇 |
2009年 | 1974篇 |
2008年 | 2041篇 |
2007年 | 2420篇 |
2006年 | 2299篇 |
2005年 | 1563篇 |
2004年 | 612篇 |
2003年 | 538篇 |
2002年 | 419篇 |
2001年 | 543篇 |
2000年 | 493篇 |
1999年 | 264篇 |
1998年 | 193篇 |
1997年 | 142篇 |
1996年 | 199篇 |
1995年 | 105篇 |
1994年 | 116篇 |
1993年 | 126篇 |
1992年 | 80篇 |
1991年 | 58篇 |
1990年 | 45篇 |
1989年 | 40篇 |
1988年 | 25篇 |
1987年 | 8篇 |
1986年 | 32篇 |
1985年 | 19篇 |
1984年 | 25篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
Travel to and from school can have social, economic, and environmental implications for students and their parents. Therefore, understanding school travel mode choice behavior is essential to find policy-oriented approaches to optimizing school travel mode share. Recent research suggests that psychological factors of parents play a significant role in school travel mode choice behavior and the Multiple Indicators and Multiple Causes (MIMIC) model has been used to test the effect of psychological constructs on mode choice behavior. However, little research has used a systematic framework of behavioral theory to organize these psychological factors and investigate their internal relationships. This paper proposes an extended theory of planned behavior (ETPB) to delve into the psychological factors caused by the effects of adults’ cognition and behavioral habits and explores the factors’ relationship paradigm. A theoretical framework of travel mode choice behavior for students in China is constructed. We established the MIMIC model that accommodates latent variables from ETPB. We found that not all the psychological latent variables have significant effects on school travel mode choice behavior, but habit can play an essential role. The results provide theoretical support for demand policies for school travel. 相似文献
912.
913.
914.
This paper investigates the effects of the provision of traffic information on toll road usage based on a stated preference survey conducted in central Texas. Although many researchers have studied congestion pricing and traffic information dissemination extensively, most of them focused on the effects that these instruments individually produce on transportation system performance. Few studies have been conducted to elaborate on the impacts of traffic information dissemination on toll road utilization. In this study, 716 individuals completed a survey to measure representative public opinions and preferences for toll road usage in support of various traffic information dissemination classified by different modes, contents, and timeliness categories. A nested logit model was developed and estimated to identify the significant attributes of traffic information dissemination, traveler commuting patterns, routing behavior, and demographic characteristics, and analyze their impacts on toll road utilization. The results revealed that the travelers using dynamic message sign systems as their primary mode of receiving traffic information are more likely to choose toll roads. The potential toll road users also indicated their desire to obtain traffic information via internet. Information regarding accident locations, road hazard warnings, and congested roads is frequently sought by travelers. Furthermore, high-quality congested road information dissemination can significantly enhance travelers’ preferences of toll road usage. Specifically the study found that travelers anticipated an average travel time saving of about 11.3 min from better information; this is about 30 % of travelers’ average one-way commuting time. The mean value of the time savings was found to be about $11.82 per hour, close to ½ of the average Austin wage rate. The model specifications and result analyses provide in-depth insights in interpreting travelers’ behavioral tendencies of toll road utilization in support of traffic information. The results are also helpful to shape and develop future transportation toll system and transportation policy. 相似文献
915.
916.
917.
This research is aimed at developing a model that maximizes system profit when determining the aircraft routes and flight frequencies in a network. The model employs network flow techniques to effectively collect or deliver passenger flows from all origins to all destinations using non‐stop and multi‐stop flights in multi‐fleet operations. The model was formulated as a multi‐commodity network flow problem. A Lagrangian‐based algorithm was developed to solve the problem. To test the model in practice, a case study is presented. 相似文献
918.
本文详细阐述了一般公路工程路基路面病害及产生病害原因,并针对路面常见病害,根据施工现场所处地质环境,结合已有经验,提出针对性解决方案。对突发性病害、预测难度大等病害,提前做出预防并提出最佳治理方案,降低病害对公路工程的破坏。 相似文献
919.
深圳中信地下商场位于城市繁华地段,地面交通繁忙、地下管线密布,工程地质、水文地质条件复杂,因此采用了以浅埋暗挖和洞内加固为主的施工技术.文章重点介绍了超大管棚预加固技术、开挖方法的研究及优化、二次衬砌的体系转换及监控量测,对其他城市地下空间的开发具有一定的借鉴价值. 相似文献
920.
盾构下穿建(构)筑物控制沉降注浆技术研究与应用 总被引:2,自引:0,他引:2
北京地铁黄村站-义和庄站区间隧道采用盾构法施工,由于下穿建(构)筑物群及12股轨道群,施工中在地面不具备加固条件的情况下采用了隧道内部超前注浆和径向注浆加固措施,即通过盾构机的8个超前注浆孔对刀盘前上方土体进行加固,在盾构机头过后利用管片上的预留注浆孔及时对隧道上方土体进行深孔注浆加固,有效地控制了地面建(构)筑物的最终沉降量.文章对本工程的概况、地层沉降机理、注浆措施及对沉降的控制效果进行了研究和分析. 相似文献