全文获取类型
收费全文 | 1538篇 |
免费 | 125篇 |
专业分类
公路运输 | 297篇 |
综合类 | 709篇 |
水路运输 | 245篇 |
铁路运输 | 273篇 |
综合运输 | 139篇 |
出版年
2024年 | 5篇 |
2023年 | 9篇 |
2022年 | 30篇 |
2021年 | 59篇 |
2020年 | 49篇 |
2019年 | 40篇 |
2018年 | 32篇 |
2017年 | 39篇 |
2016年 | 68篇 |
2015年 | 56篇 |
2014年 | 135篇 |
2013年 | 121篇 |
2012年 | 137篇 |
2011年 | 133篇 |
2010年 | 102篇 |
2009年 | 94篇 |
2008年 | 106篇 |
2007年 | 145篇 |
2006年 | 106篇 |
2005年 | 54篇 |
2004年 | 52篇 |
2003年 | 29篇 |
2002年 | 18篇 |
2001年 | 17篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1989年 | 2篇 |
排序方式: 共有1663条查询结果,搜索用时 78 毫秒
81.
Elasticities for taxicab fares and service availability 总被引:1,自引:0,他引:1
This study utilizes a unique dataset from New York City to examine the effects of taxi fare increases on trip demand and the availability of taxi service. The elasticity of trip demand with respect to fares is estimated to be –0.22; the elasticity of service availability with respect to the taxi fare is 0.28; and the elasticity of service availability with respect to total supply of service is near 1.0. These results have important implications for taxi regulatory decisions. First, fare increases do substantially increase industry revenues but at a lesser rate than the percentage increase in the fare. The implication for policy-makers is that fare elasticities must be carefully considered to obtain desired improvements in drivers' earnings. Second, service availability -- an important aspect of service quality that is generally overlooked during fare policy debates -- should be a central consideration in fare setting, given the considerable impact of fares on availability. Finally, where the supply of cabs needs to be expanded, the number of cabs can be significantly increased without harming the revenue stream of existing operators. This finding alleviates a major industry objection to issuing additional taxicab licenses. 相似文献
82.
This paper analyzes the effect of universal service policies on the airline markets of five European Union countries (France, Germany, Italy, Spain and the United Kingdom) in the period 2002–2010. Results show that airfare discount schemes for island residents raise demand and positively affect competition and the number of flights at the route level. These effects are evident in France and Italy, but are particularly marked in Spain. By contrast, public service obligations (PSOs) reduce competition on the protected routes, while their effect on the number of flights differs depending on national regulations. In Spain, routes protected with PSOs have greater flight frequencies than those on unprotected routes of similar characteristics, but in France, Italy and the UK the opposite result is found. The empirical model also finds that on routes with low-cost airlines market concentration is smaller and there is a larger number of flights. This result is relevant for the design of universal service policy, since in recent years low-cost airlines have entered a number of thin routes and have increased access to air transportation. 相似文献
83.
Downs (1962) and Thomson (1977) suggested that highway capacity expansion may produce counterproductive effects on the two-mode (auto and transit) transport system (Downs–Thomson Paradox). This paper investigates the occurrence of this paradox when transit authority can have different economic objectives (profit-maximizing or breakeven) and operating schemes (frequency, fare, or both frequency and fare). For various combinations of economic objectives and operating schemes, the interaction between highway expansion and transit service is explored, as well as its impact on travelers’ mode choices and travel utilities. Further, for each combination, the conditions for occurrence of the Downs–Thomson Paradox are established. We show that the paradox never occurs when transit authority is profit-maximizing, but it is inevitable when the transit authority is running to maximize travelers’ utility while maintaining breakeven. This is because the former transit authority tends to enhance transit service (e.g., raise frequency or reduce fare) when facing an expanded highway; and on the contrary, the latter tends to compromise transit service (e.g., reduce frequency or raise fare). Both analytical and numerical examples are provided to verify the theoretical results. 相似文献
84.
85.
86.
对北京地铁新线100 km/h车辆热容量问题进行了分析,对4种基础制动装置的配置方案进行了探讨。 相似文献
87.
88.
89.
90.