全文获取类型
收费全文 | 1426篇 |
免费 | 22篇 |
专业分类
公路运输 | 568篇 |
综合类 | 45篇 |
水路运输 | 372篇 |
铁路运输 | 48篇 |
综合运输 | 415篇 |
出版年
2023年 | 14篇 |
2022年 | 38篇 |
2021年 | 13篇 |
2020年 | 6篇 |
2019年 | 14篇 |
2018年 | 29篇 |
2017年 | 38篇 |
2016年 | 64篇 |
2015年 | 21篇 |
2014年 | 72篇 |
2013年 | 193篇 |
2012年 | 78篇 |
2011年 | 75篇 |
2010年 | 82篇 |
2009年 | 98篇 |
2008年 | 72篇 |
2007年 | 41篇 |
2006年 | 32篇 |
2005年 | 35篇 |
2004年 | 24篇 |
2003年 | 23篇 |
2002年 | 26篇 |
2001年 | 20篇 |
2000年 | 21篇 |
1999年 | 19篇 |
1998年 | 14篇 |
1997年 | 17篇 |
1996年 | 20篇 |
1995年 | 25篇 |
1994年 | 12篇 |
1993年 | 19篇 |
1992年 | 10篇 |
1991年 | 11篇 |
1988年 | 6篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 12篇 |
1982年 | 8篇 |
1981年 | 15篇 |
1980年 | 9篇 |
1979年 | 13篇 |
1978年 | 5篇 |
1977年 | 12篇 |
1976年 | 15篇 |
1975年 | 18篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1972年 | 4篇 |
排序方式: 共有1448条查询结果,搜索用时 0 毫秒
211.
212.
213.
This study was designed to examine the relationship between actual and perceived values of cost and time for the work trip and to examine how perceptions have changed over a period of dramatically increased travel costs. Variations in the relationship between perceived and actual values were examined as a function of situational and attitudinal variables. Two telephone surveys were conducted one year apart (Fall 1978 and Fall 1979). On the next working day following a survey, a research assistant recreated the respondent's work trip, recorded time values and used distance measures, car type information and parking costs to compute travel cost. The first survey revealed that most auto users were unable to articulate dollars-and-cents driving costs for the work trip, but auto users in the second survey were able to provide fairly accurate cost estimates. Dramatic changes in fuel prices between surveys is probably the main reason for the change in driving cost awareness. Auto users were also asked to rate relative costs of driving a car compared to using the bus for the work trip. These ratings showed that auto users tended to underestimate driving costs relative to bus costs, but this tendency decreased from the first to the second time period. Commuters in all modal groups at both time periods tended to overestimate travel times. Perception of travel time varied as a function of mode, perceived comfort (for car users), and perceived convenience and number of transfers (for bus users).To whom correspondence should be addressed. 相似文献
214.
Robert H. Robimson 《Maritime Policy and Management》1976,4(1):21-31
The United States Congress reasserted the desire for continued financial support to domestic merchant-ship construction when in 1970 it amended the Merchant Marine Act of 1936 [1]. With regard to the shipbuilding industry, the most significant changes contained in the Merchant Marine Act of 1970 [2] are those designed to reduce the construction differential subsidy and to increase the variety of vessels that might be subsidized. Sections 501(a), 502(a), and 502(b) of the 1936 Act were amended to facilitate the reduction in subsidies; Section 905(a) was modified to encourage the subsidized construction of liquid and dry bulk cargo vessels. After a cursory review of the 1970 amendments to the 1936 Act, this paper is directed to ascertaining the results, in general, of the changes and whether they have generated increased domestic shipyard productivity and lower subsidy rates. 相似文献
215.
I. H. McNicoll 《Maritime Policy and Management》1982,9(4):259-272
This paper analyses the contribution of the fishing industry (catching and processing) to economic activity in the Shetland Islands. Using a Shetland input-output table, the economic characteristics of the industry itselfare discussed. The impact of fishing activities on other local sectors is measured in terms of output, income and employment. Appropriate fisheries multipliers are derived. Changes in fisheries impact over the period 1971-76 are analysed. Finally, a number of scenarios relating to hypothetical changes in fishing activity are examined. 相似文献
216.
217.
218.
219.
H. D. Smith 《Maritime Policy and Management》1977,4(6):351-376
The problems associated with hydrocarbon extraction in the EEZ are discussed under the headings of resources and environment, technology and the industrial structure, government management, decision-making, and policy formulation. Policy areas identified include boundary delimitation relative to resources, environment and technology, co-ordination and decision-making machinery, relationships with UK and EEC energy policies, and regional planning of the sea and coastal areas used by the off-shore industry. 相似文献
220.
Non-Contact Suspension and Propulsion Technology 总被引:3,自引:0,他引:3
H. Alscher M. Iguchi A. R. Eastham I. Boldea 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1983,12(4):259-289
As a result of extensive research and development in several countries, the technologies of magnetic suspension and linear electric drives are becoming available for transportation applications. The successful demonstration and operation of prototype vehicles has established the technical viability of these systems. Several urban transit or shuttle services, with magnetic suspension and/or linear motor propulsion are likely to be operational within 3-4 years. After the final stages ofdevelopment and rigorous testing, high speed systems are likely to be an option for intercity implementation by the end of the decade. This paper presents a report on the worldwide status of R&D and test programs of non-contact suspension and propulsion technology for guided ground transport. 相似文献