全文获取类型
收费全文 | 1613篇 |
免费 | 4篇 |
专业分类
公路运输 | 411篇 |
综合类 | 43篇 |
水路运输 | 555篇 |
铁路运输 | 47篇 |
综合运输 | 561篇 |
出版年
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 15篇 |
2019年 | 14篇 |
2018年 | 30篇 |
2017年 | 38篇 |
2016年 | 52篇 |
2015年 | 21篇 |
2014年 | 30篇 |
2013年 | 267篇 |
2012年 | 68篇 |
2011年 | 72篇 |
2010年 | 72篇 |
2009年 | 76篇 |
2008年 | 84篇 |
2007年 | 69篇 |
2006年 | 39篇 |
2005年 | 35篇 |
2004年 | 30篇 |
2003年 | 30篇 |
2002年 | 25篇 |
2001年 | 30篇 |
2000年 | 22篇 |
1999年 | 24篇 |
1998年 | 43篇 |
1997年 | 21篇 |
1996年 | 29篇 |
1995年 | 28篇 |
1994年 | 16篇 |
1993年 | 24篇 |
1992年 | 20篇 |
1991年 | 17篇 |
1990年 | 10篇 |
1989年 | 14篇 |
1988年 | 18篇 |
1987年 | 15篇 |
1986年 | 19篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 14篇 |
1981年 | 15篇 |
1980年 | 15篇 |
1979年 | 20篇 |
1978年 | 10篇 |
1977年 | 14篇 |
1976年 | 16篇 |
1975年 | 21篇 |
1974年 | 11篇 |
1973年 | 10篇 |
排序方式: 共有1617条查询结果,搜索用时 15 毫秒
131.
The coastal zone is attractive for human settlement because it tends to be resource rich, providing a good location to generate incomes and livelihoods. Equally, however, it is a complex and powerful natural environment, which means that the coastal zone often becomes a focus of conflict with multiple users competing for limited space and resources. Understanding the causes of, and determining solutions to, the ensuing problems requires inputs from a range of analyses across sectors and disciplines. However, different disciplinary and sectoral approaches frequently use different investigative methods, language, and means of presenting results. This article presents a framework that has been developed in collaboration with Indian institutions over the past three years in an effort to address some of these fundamental problems of analysis and translation into policy action. Key components addressed by the framework are strengthening the capacity to practice, knowing how to proceed and how to find out what needs to be known using experience-based problem solving. 相似文献
132.
133.
Tiago A. Santos 《Maritime Policy and Management》2017,44(7):859-881
A novel methodology is developed for determining the characteristics of a cargo roll-on/roll-off (ro-ro) ship and the fleet size required for a given short sea shipping route. The ship and required fleet size to satisfy the transportation demand (for each pair of speed and freight rate) are determined using a database of existing cargo ro-ro ships to obtain the main technical characteristics of the most suitable ship. The time charter, voyage costs and revenue are then calculated considering the technical characteristics of each ship. Fuel costs are corrected for the actual ship speed and loading condition. A number of restrictions in the transportation problem are considered leading to the exclusion of unfeasible solutions. The maximum profit over the period of a year is identified among the feasible pairs of speed and freight rate. This general methodology is applied in a case study that considers the route between Leixões (Portugal) and Rotterdam (Netherlands). The study allows the identification of the most suitable ship and fleet sizes for different market penetration levels and quantifies the impact on shipping company profit of changes in parameters such as fuel costs, time charter costs, emission control area, installed propulsion power and stacking factor. 相似文献
134.
An altimeter data assimilation scheme has been tested in the OCCAM (Ocean Circulation and Climate Advanced Modelling) global 1/4°, 36-level model using a twin experiment format. The Cooper and Haines displacement scheme is used. The method works well in most regions and depths. Currents and densities in the top 1000 m generally improve by over 50–70% after 5 months of sea level assimilation every 15 days. Below 1000 m, an error reduction of up to 50% is achieved. The errors remain low during a further 60-day run without assimilation. Diagnostics for the North Atlantic, the Tropical Pacific and the Antarctic Circumpolar Current are shown alongside the global averages.The main problems encountered were in weakly stratified regions of the Antarctic and Arctic seas. A scale selective filter is developed to avoid assimilating scales much larger than the local deformation radius, and this avoids the adverse assimilation effects in the southern oceans. A companion paper uses this scheme to assimilate TOPEX and ERS-1 altimeter maps. 相似文献
135.
Athanasios A. Pallis 《WMU Journal of Maritime Affairs》2007,6(1):3-20
Throughout Europe, a number of maritime interests have re-targeted their lobbying structures and strategies aiming to influence
the development of the maritime related European Union (EU) policies. The paper examines these maritime interests’ mobilisation
in the making of the Common EU Maritime Transport Policy (CMTP). First, it provides a review of the role of these interest
groups and the implications of the observed collective interests’ representation. Then, with the contribution a data-set of
replies to a questionnaire distributed to all the interest groups that are involved in EU maritime affairs, the paper analyses
the variety of interest groups representing the maritime sector in EU affairs. The focus is on the structures (i.e. membership
numbers and types, location, internal structures, budget) and the lobbying practices of the 37 identified EU level maritime
related organisations. The paper also presents an evaluation of the most positive and most negative parameters of the ‘EU
environment’ and the ‘economic environment’ that assist, or undermine, the governability cohesiveness of this collective action.
This study provides information on whether and under what conditions maritime interests are able to form comprehensive EU-level
organisations capable of representing their members and their interests in the EU policy making process 相似文献
136.
On November 30, 2006, USS Boone (FFG 28) lost all steering control in the Mediterranean Sea due to a lost rudder. Within hours of the casualty, numerous US Navy and contractor activities sprung into action to coordinate and complete an emergent voyage repair to return USS Boone to service to support the Global War on Terrorism. The Navy faced a large hurdle to identify and transport a replacement rudder to Rota, Spain, and prepare and carry out an extremely complex repair procedure. Pearl Harbor Naval Shipyard personnel removed the replacement rudder from USS Crommelin (FFG 37) in Pearl Harbor Naval Shipyard and transported the rudder to Rota, Spain. The Navy's Supervisor of Salvage and Diving developed the repair procedure and coordinated the repair operation, which involved over 30 US Navy and contractor divers. The repair team completed the rudder replacement on December 28, 2006 and returned USS Boone to underway operations. 相似文献
137.
138.
In this paper, the dynamic response of a scale model of a jacket offshore structure is investigated both theoretically and experimentally. The experiments were conducted both in air and in water. The in-water experiments were done in the towing tank of Memorial University to simulate the realistic operating conditions. The model was subjected to random wave loads. Froude's law of modeling was used to obtain the dimensions of the scale model based on the dimensions of an existing structure. The effects of varying the structure's weight, and the characteristics of the wave loading were investigated. The structure's weight was changed by adding weights to the structure's deck. A finite element model was designed to determine the dynamic response of the model. Excellent agreement between the experimental and theoretical results was obtained.The reaction force at the foundation was estimated from strain measurements and compared with the finite element calculations. Fair agreement was obtained.This work is the first stage of a project whose objective is to develop a method for structural damage detection using the free vibration response of the structure. The free vibration response will be obtained from the stationary random response of the structure using the random decrement method. Having an accurate model to describe the dynamic response of the structure is the first step in this study. 相似文献
139.
Tudor D. Bodea Laurie A. Garrow Michael D. Meyer Catherine L. Ross 《Transportation Research Part A: Policy and Practice》2009,43(4):430-444
This paper explores the association of socio-demographic and built environment characteristics on the odds of being overweight and obese using data from the Atlanta SMARTRAQ travel survey. A new methodological framework based on a multinomial logit (MNL) model and an enhanced odds ratio plot is presented. The use of an MNL model overcomes limitations of many prior studies that employ a sequence of binary logit models to examine multiple weight categories. The use of an enhanced odds ratio plot provides important information into the relative importance of socio-demographic and built environment characteristics. Several new findings for the Atlanta area result from this study. Socio-demographic variables, including age and educational attainment, exhibit a non-linear relationship with the odds of being overweight or obese. Gender, age, ethnicity, and educational attainment are strongly associated with the odds of being overweight or obese, while income and number of students between 5 and 16 years old in the household have smaller effects. Built environment characteristics such as increased net residential densities and enhanced street connectivity are associated with reductions in the odds of being overweight and/or obese. Relative to socio-demographic variables, however, such built environment characteristics have a much smaller impact on describing the odds of being overweight or obese. 相似文献
140.