首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2240篇
  免费   21篇
公路运输   664篇
综合类   74篇
水路运输   747篇
铁路运输   70篇
综合运输   706篇
  2022年   32篇
  2021年   18篇
  2020年   17篇
  2019年   20篇
  2018年   60篇
  2017年   55篇
  2016年   72篇
  2015年   23篇
  2014年   74篇
  2013年   352篇
  2012年   117篇
  2011年   123篇
  2010年   104篇
  2009年   100篇
  2008年   101篇
  2007年   72篇
  2006年   49篇
  2005年   52篇
  2004年   32篇
  2003年   45篇
  2002年   37篇
  2001年   43篇
  2000年   28篇
  1999年   34篇
  1998年   54篇
  1997年   35篇
  1996年   44篇
  1995年   35篇
  1994年   23篇
  1993年   27篇
  1992年   30篇
  1991年   18篇
  1990年   19篇
  1989年   21篇
  1988年   20篇
  1987年   17篇
  1986年   17篇
  1985年   16篇
  1984年   17篇
  1983年   11篇
  1982年   18篇
  1981年   23篇
  1980年   24篇
  1979年   24篇
  1978年   15篇
  1977年   17篇
  1976年   16篇
  1975年   25篇
  1974年   12篇
  1973年   12篇
排序方式: 共有2261条查询结果,搜索用时 390 毫秒
131.
Fuel consumption is calculated using a modelling procedure for automobiles travelling on three alternative street patterns designed for a subdivision in Kingston Township, Ontario. The modelling procedure is described. The results indicate that grid and solar superblock street patterns, compared to the existing street pattern, offer small fuel savings to a tripmaker in the portion of the work trip travelled in the subdivision.  相似文献   
132.
This paper discusses negotiations, relative to sea fisheries, in terms of international arrangements—arrangements between the European Economic Community (EEC) and Third Countries; and those between member states of the EEC.  相似文献   
133.
134.
This paper analyzes the energetic performance of the hybrid Lexus RX 400h, through on-board measurements. Several speed profiles were analyzed, for three driving types, successive stop and go cycles, three speed profiles, crossing an electronic toll collection booth, and a roundabout. In stop and go situations the internal combustion engine did not work (the torque needed to impulse the vehicle in the stop and go situations was only supported by the electric engines), as well as in the situations of constant low speeds (50 or 60 km h?1). The auxiliary support given by the electric engines in the accelerations, as well as the importance of the energy regeneration system on the batteries’ load recovery is also demonstrated. When compared with similar conventional vehicles, the Lexus RX 400h has lower combined energy consumption between 1.2% and 60%.  相似文献   
135.
State agencies responsible for ADA-eligible paratransit services are increasingly under pressure to contain costs and maximize service quality. Many do not operate vehicles themselves; instead, they contract out the provision of services. Contractors are paid for each hour of service. They are responsible for hiring crew, forming routes, dispatching, and operating and maintaining agency-owned vehicles. In the Twin Cities of Minneapolis and Saint Paul, Metro Mobility, the agency responsible for providing paratransit services, requires contractors to use agency-approved software for booking trips dynamically and sets parameters that guide contractors’ practices. Customer trips booked in this fashion may not utilize capacity in the most efficient manner. Therefore, beginning with the daily trip schedules generated by the software, this paper proposes two approaches for improving the efficiency of paratransit operations and estimates the benefit of using these approaches via experiments that utilize Metro Mobility data. The first approach re-optimizes routes developed at the end of each day. The second approach evaluates the benefit to state agencies of selectively using non-dedicated service providers such as taxis. Both approaches are tested on actual data obtained from Metro Mobility. The study shows that a conservative estimate of savings from re-optimization would be approximately 5% of Metro Mobility’s operating costs. Savings from the use of taxis are smaller and in the range of hundreds of dollars per day.  相似文献   
136.
This study assesses the effects of aircraft noise on residential satisfaction, an important indicator of subjective well-being. A structural equation model is specified that estimates the relationships between objective variables, noise annoyance variables and residential satisfaction. Secondary data-analysis is used to estimate the model. The survey was conducted in 1996/1997 among the population living within a 25-km radius of Amsterdam Schiphol, the largest airport in the Netherlands. The effect of aircraft noise annoyance is found to be relatively small. In addition, the objective level of aircraft noise exposure is found to be a better predictor of residential satisfaction than its subjective counterpart. The most important determinants of residential satisfaction are found to be road traffic noise annoyance, age and neighbor noise annoyance.  相似文献   
137.
138.
A regional railroad network is presented to evaluate the system's response to increased coal traffic. An optimal, multimodal, coal-shipping pattern is developed for the study region to minimize total costs and to efficiently use the existing network. A two-stage, general model allocates resources among demands and then assigns flows to the network according to efficiency criteria. The model is sufficiently general to permit modification for specific needs, assumptions and data. Government agencies and industries can apply the model in resource allocation decisions and transportation policy analysis.  相似文献   
139.
Hybrid vehicles of different configurations and utilizing different energy storage systems have existed in development for many decades and more recently in limited production. They can be grouped as parallel, series or complex hybrids. Another classification is micro, mild and full hybrids which makes the distinction on the basis of functionality. The common energy storage systems in hybrid vehicles are batteries, supercapacitors and high speed flywheels. This paper aims to review a specific type of hybrid vehicle which involves the internal combustion engine (ICE) as the prime mover and the high speed flywheel as an energy storage device. Such hybrids are now attracting considerable interest given their potential for low cost. It is hence timely to produce a review of research and development in this subject. The flywheel is coupled to the drive line with a continuous variable transmission (CVT). The CVT can be of various types such as electrical, hydraulic or mechanical but usually in this case it is a non-electrical one. Different configurations are possible and the paper provides a timeline of the development of such powertrains with various examples. These types of hybrid vehicles have existed as prototypes for many decades and the authors believe that their development has reached levels where they can be considered serious contenders for production vehicles.  相似文献   
140.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号