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41.
A World that shrinks with progressive improvements in transportation and communications is a fact of 20th century life. The shrinking process can produce new patterns and perceptions of strategic location. In this paper we are looking specifically at nodes in transportaion system. In the ligth of transportation progress, we re-consider some of the time-worn ideas about centrality, accessibility, gateway locaations, junction, transit points, and the like. Do some of these notions become irrelevant in the modern transport age? Is it a questions f shifting geographical scale? Do we need more sophisticated concepts of strategic location? We suggest the answer 'yes' to all three questions. Our illustrations come from an examination of the world's top-ranked container ports. We give primary emphasis to the external geographical relationships of the ports, that is to situational aspects (not to say, however, that sitefeatures are inconsequetial). We are interested in the seaports users' —i.e., carriers and shippers—perceptions of strategic location. Readily available container throughput data provide and initial platform for empirical research but also give proof that some commercial interests find these ports strategically important to their system. 相似文献
42.
朱本章 《西安交通大学学报(医学版)》1996,(3)
报道了成功地亚克隆Zfhag的锌指结构和同结构域基因,并将其在细菌体内表达成麦芽糖结合蛋白的融合蛋白的方法和结果,使用这些表达蛋白进行了蛋白-DNA相互作用的研究。结果表明:MBP-ZD1和MBP-ZD2蛋白能与糖蛋白激素的α亚基基因、鼠生长激素(γ-GH)基因和促甲状腺激素β亚基(TSH-β)基因的甲状腺激素反应成分(TRE)结合,而不能结合含有天然TRE的MHC和F2H基因,及含有合成TRE的DR4和PAL寡核苷酸。 相似文献
43.
W.Bruce Allen Mohamed M. Mahmoud Douglas McNeil 《Transportation Research Part B: Methodological》1985,19(5):447-456
Reliability of transit time is reputed to be the most important variable influencing freight transport today, according to shipper surveys. Average transit time also plays a major role. A model is developed that shows how a cost-minimizing shipper will adjust its economic order quantity as reliability and/or time in transit changes. Such changes impact on average inventory costs, ordering costs, expected shortage costs and expected excess costs. The model is developed for both discrete and continuous transit time distributions. Reliability is defined as the variance of transit time. A matrix is prepared for some sample data, which shows the minimum cost attainable with each mean/variance of transit time distribution. Comparing across rows and columns of the matrix enables one to show the value (reduction in total cost) obtainable by improving reliability and/or mean transit time. In addition, value can be obtained by improving reliability while increasing average transit time. It is suggested that the model can be used for shippers in negotiating service improvements with carriers and by carriers in negotiating service improvements with shippers. In the former case, the carrier can determine how much they are willing to pay for the improvement, whereas in the latter case, the carriers can determine how much they are able to charge for the improvement. 相似文献
44.
Douglas O.A. Osula 《Transportation Research Part A: Policy and Practice》1998,32(8):599-606
The paper presents a procedure that has been developed for estimating subsidization requirements for urban transit services in developing countries. The procedure is based on a subsidization policy of reducing transport expenditure burden on the average commuter, by maintaining his transport expenditure-income ratio at a reasonable level. It is designed for both regulated and deregulated transport markets. It requires, as input, historical data (previous year) on fare, productivity, and load factor for the transport service or mode concerned, the transport expenditure-income ratio distribution of the commuters, and the current level of commuter personal transport allowance. It is based on the premise that transport expenditure-income ratio is inversely related to income. The subsidization formula developed in the paper yields a level of subsidy that is commensurate with the level of control a government is able to exercise over transit operations. 相似文献
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Douglas K. Fleming 《Maritime Policy and Management》1981,8(4):281-283
The University of Washington recently (1981) established a College of Ocean and Fishery Sciences which incorporates extant programmes in oceanography, fisheries and other marine resource fields. The Institute for Marine Studies (IMS), organized in 1972 and presently directed by Professor Warren Wooster, is one component of the new college. IMS, a multidisciplinary academic and research unit, focuses on the management and policy issues arising from the many different uses of marine and coastal resources. 相似文献
49.
To date only limited research has quantified differences between female and male activity patterns, and analyses at an individual activity level are scarce. Past research has focused on investigating gender differences in mobility levels based on observed travel patterns, especially those related to commuting. This article reports new evidence based on analyses of a household activity survey data-set collected from a Canadian city – Calgary – in 2001. Results show that contemporary females and males have a very similar activity participation pattern. On the other hand, analyses applied to activity starting times support the view that there are minor gender differences in time-of-day choices. In addition, duration and survival analyses through log-rank and Wilcoxon tests show that women and men tend to spend more or less time on some of the 10 weekend/weekday activities, and thus indicate that they share different domestic and societal responsibilities: males tend to spend longer time for out-of-home activities, such as work, school, social, and out-of-town; whereas females contribute more to domestic work, including shopping, eating, and religious activity. In general, this article contributes new evidence to gender differences in activity participation, time-of-day, and duration choices at the individual activity level. Such differences may influence travelers’ time, mode, and location choices and thus have important implications for the complexity of an activity-based modeling framework. These implications are discussed along with recommendations for incorporating gender differences in an activity-based modeling framework. 相似文献