全文获取类型
收费全文 | 3518篇 |
免费 | 23篇 |
专业分类
公路运输 | 687篇 |
综合类 | 755篇 |
水路运输 | 1168篇 |
铁路运输 | 74篇 |
综合运输 | 857篇 |
出版年
2023年 | 18篇 |
2022年 | 43篇 |
2021年 | 25篇 |
2020年 | 15篇 |
2019年 | 15篇 |
2018年 | 382篇 |
2017年 | 322篇 |
2016年 | 301篇 |
2015年 | 27篇 |
2014年 | 80篇 |
2013年 | 233篇 |
2012年 | 136篇 |
2011年 | 282篇 |
2010年 | 295篇 |
2009年 | 138篇 |
2008年 | 256篇 |
2007年 | 161篇 |
2006年 | 60篇 |
2005年 | 94篇 |
2004年 | 67篇 |
2003年 | 86篇 |
2002年 | 46篇 |
2001年 | 25篇 |
2000年 | 24篇 |
1999年 | 29篇 |
1998年 | 35篇 |
1997年 | 27篇 |
1996年 | 23篇 |
1995年 | 20篇 |
1994年 | 8篇 |
1993年 | 14篇 |
1992年 | 19篇 |
1991年 | 19篇 |
1990年 | 11篇 |
1989年 | 16篇 |
1988年 | 12篇 |
1987年 | 9篇 |
1985年 | 20篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1976年 | 10篇 |
1975年 | 11篇 |
1974年 | 15篇 |
1972年 | 7篇 |
排序方式: 共有3541条查询结果,搜索用时 468 毫秒
671.
672.
The galvanic corrosion behaviour of aluminium 3004-∝brass with different area ratios was studied in the tropical marine atmosphere at Tuticorin harbour over a period of 426 days. The area ratios, viz. A Aluminium:A∝ brass, studied were 0.125, 0.25, 0.5, 1, 2, 4 and 8. The galvanic corrosion behaviour of the metals was studied in terms of the relative increase in the corrosion rate of aluminium due to galvanic coupling with ∝ brass, the relative decrease in the corrosion rate of ∝ brass due to galvanic coupling with aluminium, and the susceptibility of aluminium to pitting owing to galvanic coupling with ∝ brass. The galvanic potential and galvanic current of the system were monitored. Pits of different dimensions ranging from mild etchings to perforations were experienced on the borders and the surfaces of the interface of aluminium in contact with ∝ brass. The corrosion products resulting from galvanic corrosion were analysed using XRD and the pitting on aluminium as a result of galvanic corrosion was highlighted in terms of pit depth, size and density of pit, using a high resolution microscope. The most favourable area ratio of aluminium-∝ brass in marine atmosphere in terms of gravimetric corrosion rate is 8:1 and the most unfavourable area ratio of aluminium-∝ brass is 1:4. 相似文献
673.
Cycling is often promoted as a means of reducing urban congestion and improving health, social and environmental outcomes. However, the quantification of these potential benefits is not well established. This is due in part to practical difficulties in estimating cycling demand and a lack of sound methodologies to appraise cycling initiatives. In this paper we attempt to address this need by developing predictive models of cycle demand, relative to other transport modes, that capture not only the impacts of observed characteristics such as age and travel time but also the role of attitudes and perceptions. Using data from a stated preference survey, we estimate a hybrid choice model for cycle use that incorporates the role of attitudes towards cycling, perceptions of the image associated with cycling, and the stress arising from safety concerns. Model results indicate that the latent attitudes and perceptions explain an important part of the non-observable utility in a simple multinomial logit choice model. We also demonstrate policy analysis using the hybrid choice model, which allows comparisons of ‘hard’ policies such as the provision of parking facilities against ‘soft’ measures such as cycle promotion schemes. 相似文献
674.
Using Herfindahl–Hirschman Index and the Mobidrive and Thurgau six-week travel diary datasets this paper examines the degree of repetition of individuals’ choices of their daily activity–travel–location combinations. The results show that the repetitiveness of individual activity–travel–mode–location combinations is highly influenced by the individuals’ out-of-home commitments, the intra-household conditions and the availability and the accessibility of the activity locations. Different types of activity have different pattern of repetition. The level of repetition of individual’s daily activity–travel pattern is less correlated to travel mode choice, but more to the individuals’ commitments and obligations. The repetitiveness of mode choices is more related to the conditions or the accessibilities of the activity location, but not directly to the activity itself. 相似文献
675.
Junghwa Kim Jan-Dirk Schmöcker Cecilia Jakobsson Bergstad Satoshi Fujii Tommy Gärling 《Transportation》2014,41(4):855-872
Previous research has shown that fairness, infringement on freedom, and perceived effectiveness are determinants of transport pricing acceptability. In the present study we investigate determinants of acceptability of environmental (carbon) taxation for which trust in government and environmental concern are additional determinants. Carbon taxation is an extension of fuel taxes and may thus be viewed as transport pricing. Our main focus is on the role played by personality traits. Structural equation modeling reveals that acceptability is related to the personality traits extraversion, agreeableness, and conscientiousness. Extraverted individuals have higher levels of trust in government which leads to higher acceptability. Also correlations between agreeableness and conscientiousness as well as environmental problem awareness and personal norm are observed. We discuss strategies for effective marketing of transportation policies considering how acceptability is related to personality traits. 相似文献
676.
677.
678.
营运中的盾构隧道在邻近施工时周围地盘的应力可能因扰动而重新分布,使得盾构隧道暴露在因变形或位移衍生的结构损坏或营运中断等高风险下。为降低相关风险发生的可能性或后果的严重性,高雄计划将高雄车站段地下化工程捷运-R11永久站施工纳入风险管理,通过风险辨识、分析、评估以及以监测、巡检及沟通为基础的风险追踪查核等手段执行风险管理。依本计划执行成果,位于基地两侧营运中的盾构隧道在永久站主体工程开挖施工期间,各项风险均受到妥善的追踪、管控及处置。 相似文献
679.
贺江下游航道兼有山区河流和渠化河流的特点,枯水季节局部航道出浅,长期以来等级低下,水运发展缓慢,影响了航运效益的发挥。建立了一维数学模型,研究枢纽调度运行条件下贺江下游航道的水位衔接问题、碍航浅滩的长度;并考虑山区河流枢纽渠化河段以及河口入汇自然河段的航道整治宽度、航道疏浚条件下水位的降落程度,分析了贺江航道适宜提高航道等级的可行性与适用条件。最后将碍航浅滩的长度、航道整治宽度和水位的降落程度作为航道优化等级确定的参数,综合确定了贺江下游航道的优化开发等级为Ⅳ级。 相似文献
680.
This paper presents a detailed exploratory analysis of joint activity participation characteristics using the American Time
Use Survey (ATUS). As a very large nationwide survey that explicitly elicited information on both household and non-household
companions for each activity episode, the ATUS is ideally suited for this analysis. Several intuitive and interesting results
are obtained. Joint episodes are found to be of longer durations, significantly likely to take place at the residence of other
people, and often confined to certain time periods of the weekday. In addition, important differences in these characteristics
are also observed based on activity purpose, companion type, and the day of the week. These findings are intended to provide
the basis for the justification of detailed collection of joint activity–travel participation information in household activity–travel
surveys, and also as a stimulant for further empirical analysis and modeling of joint activity participation behavior.
相似文献
Chandra R. BhatEmail: |