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61.
yvind Thiem Elisa Ravagnan Jan Helge Foss Jarle Berntsen 《Journal of Marine Systems》2006,60(3-4):207-219
In recent years it has been documented that deep-water coral reefs of the species Lophelia pertusa are a major benthic habitat in Norwegian waters. However, basic information about the biology and ecology of this species is still unknown. Lophelia live and thrive under special environmental conditions of which factors such as temperature, water depth, water movement and food supply are important. The present work explores the hypothesis that Lophelia forms reefs in places where the encounter rate of food particles is sufficiently high and stable over long periods of time for continuous growth. This is done by relating the distribution of reefs with the results of numerical ocean modelling.Numerical simulations have been performed with an idealized bottom topography similar to what is found outside parts of the Norwegian coast. In the simulations the model is first forced with an along slope jet and then with an idealized atmospheric low pressure. The model results show that the encounter rates between the particles and the water layer near the seabed are particularly high close to the shelf break. This may indicate that many Lophelia reefs are located along the shelf edges because the supply of food is particularly good in these areas.A sensitivity study of the particle supply in the area close to the seabed for increasing latitude has also been done. This shows that the Ekman transport in the benthic layer tends to create a steady supply of food for benthic organisms near the shelf edge away from the equator. 相似文献
62.
如果我们对比蒙大拿州冰河国家公园历史和当前的照片,我们就可以轻易地发现冰川正在消融,海平面正在上升。目前人们普遍认为全球变暖是碳排放造成的恶果。2007年2月2日,联合国环境规划署发布了迄今为止关于气候变化最权威的科学报导。有九成的把握认为,矿物燃料的使用及其他人类活动导致了气候变化。 相似文献
63.
Jan Hromádko Petr Miler Jiří Hromádko Vladimír Hönig Michal Schwarzkopf 《Transportation Research Part D: Transport and Environment》2010,15(2):103-107
This article deals with the influence of three-way catalysts on the production of basic emissions, such as carbon monoxide, unburned hydrocarbons and nitrogen oxides from spark-ignition engines. A virtual simulation of the new European driving cycle is used. Characteristics of components in emissions in the front and back of the catalyst are measured on the test bed to form the basis of the simulation. The results relate to emissions for 1 km travelled. 相似文献
64.
Jan A. Van Der Linden 《Maritime Policy and Management》2013,40(1):33-54
Input-output analysis basically provides an estimation of a sector's economic impact by taking into account the indirect effects on all other sectors. For purposes of policy making, however, this may produce rather rigid and inaccurate results. This paper, therefore, introduces some extensions to the basic impact analysis. These extensions secure flexibility, completeness and accurateness of the outcomes. First, an accurate cost structure is determined in a bottom-up approach, i.e. by using data from a sample of representative companies. This allows for reliable outcomes and a flexible definition of sub-sectors. Secondly, the analysis is made in an intercountry context. Thirdly, the expenditure effects of generated income are determined by a macroeconomic module. Fourthly, company-level responses to alternative policy scenarios are investigated and translated into changing model parameters. These four basic elements are applied in a case study concerning the shipping sector of Germany. The scenarios are a continuation of the present policy, a laissez-faire policy, and two framework policies in which the government creates a favourable environment for shipping companies. For each scenario, the effects on value added, employment, tax revenues and expenditures are analysed and evaluated. This paper, thus, shows the relevance of accordingly amplified input-output analysis for policy purposes. 相似文献
65.
丹麦可能是世界上最容易找到好车的地方:当然我们说的是自行车。理由之一:在丹麦有近1/3的人是骑车上班,理由之二同时丹麦又是一个以设计闻名的国家。下面就来说说我们这位来自丹麦的主角:Michael Ubbesen Jakobsen—— 相似文献
66.
Measuring the welfare effects of infrastructure: A simple spatial equilibrium evaluation of Dutch railway proposals 总被引:1,自引:0,他引:1
We specify a spatial computable general equilibrium model for the Netherlands based on the so-called New Economic Geography. The model distinguishes 14 sectors, two modes of transportation and over 500 municipalities. Key parameters are estimated by fitting predicted interregional trade flows to bi-regional input-output data. The model is then calibrated to a baseline scenario for 2020. From there, the transport grid is modified in line with six proposals for changes in rail infrastructure. The effects of these changes on employment and welfare are computed. We find that the most ambitious project leads to a redistribution of around 8000 jobs from regions further out to regions along the line and especially at the end of it. The net national welfare effect is equivalent to a 250 million euro (0.016%) increase in GDP. 相似文献
67.
This study seeks to identify factors that promote innovation in shipping companies. The study is based on an empirical investigation of 63 companies headquartered in Norway. The results imply that organizational and interorganizational variables are important to innovation. Three aspects of innovation are focused on: (1) service/product innovations, (2) market innovations, and (3) production method innovations. The explanatory variables that are applied in this study capture between 13–51% of the variability of the measures of innovation. The results indicate that an explicit strategy that promotes innovation is very important for the actual level of innovation within shipping companies. In management literature, it is often assumed that organic organizational features like decentralized decision-making promote innovation. The opposite features are assumed to restrain innovation. However, the results do not support these basic assumptions. For example, it seems to be important that managers make precise decisions in order to promote innovation. 相似文献
68.
Jan Horck 《Maritime Policy and Management》2013,40(1):15-29
This paper presents a simple formulation in the form of a pipe network for modelling the global container-shipping network. The cost-efficiency and movement-patterns of the current container-shipping network have been investigated using heuristic methods. The model is able to reproduce the overall incomes, costs, and container movement patterns for the industry as well as for the individual shipping lines and ports. It was found that the cost of repositioning empties is 27% of the total world fleet running cost and that overcapacity continues to be a problem. The model is computationally efficient. Implemented in the Java language, it takes one minute to run a full-scale network on a Pentium IV computer. 相似文献
69.
70.
新开发的安装在海底的永久性纤维光学地震监控系统,大大提高了近海石油行业海底建模精度,并加快了石油开采速度。 相似文献