全文获取类型
收费全文 | 1106篇 |
免费 | 3篇 |
专业分类
公路运输 | 206篇 |
综合类 | 43篇 |
水路运输 | 342篇 |
铁路运输 | 32篇 |
综合运输 | 486篇 |
出版年
2022年 | 17篇 |
2021年 | 11篇 |
2020年 | 13篇 |
2019年 | 13篇 |
2018年 | 33篇 |
2017年 | 25篇 |
2016年 | 42篇 |
2015年 | 8篇 |
2014年 | 23篇 |
2013年 | 200篇 |
2012年 | 46篇 |
2011年 | 54篇 |
2010年 | 56篇 |
2009年 | 51篇 |
2008年 | 45篇 |
2007年 | 44篇 |
2006年 | 34篇 |
2005年 | 25篇 |
2004年 | 9篇 |
2003年 | 19篇 |
2002年 | 12篇 |
2001年 | 17篇 |
2000年 | 24篇 |
1999年 | 14篇 |
1998年 | 22篇 |
1997年 | 17篇 |
1996年 | 14篇 |
1995年 | 21篇 |
1994年 | 9篇 |
1993年 | 15篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 8篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1985年 | 15篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1980年 | 7篇 |
1979年 | 7篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1972年 | 6篇 |
排序方式: 共有1109条查询结果,搜索用时 15 毫秒
1.
2.
Standardized and free-format questionnaires on the state of coastal management were fielded to coastal management practitioners during three workshops and a national feedback and recommendation workshop. The most commonly cited responses were identified for each of 13 political regions and overall trends were identified. Management frameworks frequently included research, community organizing, education, livelihood, resource enhancement, resource protection, regulation, and networking components. Gender issues, documentation, and infrastructure investment were rare. The most commonly perceived environmental problem was illegal/ destructive fishing and its associated overfishing and low fish catch. The most commonly cited socioeconomic problem was the inadequacy of law enforcement. The best monitored variables were usually those related to environmental management: status and change of habitats, resources, and degree of enforcement/patrolling activities. The most common nonregulatory enhancement, aside from environmental education (which is the most popular), was mangrove reforestation. In terms of regulations, the majority of the respondents have reportedly formulated an integrated coastal management plan. In practice, regulating destructive and illegal fishing practices and then the establishment of fish sanctuaries are the next most implemented. The most popular quality-of-life enhancement strategies focused on the improvement of sustainable fishing as a livelihood and on a variety of supplementary livelihoods. The most usual institutional intervention being implemented was the setting up of local community people's organizations. Major factors which may influence success or failure of coastal management and recommendations on research, community organizing and livelihood, legislation and policies, implementation and coordination, and networking are also summarized. 相似文献
3.
克诺尔机车车辆制动公司开发了模块化的标准制动控制系统MBS,只需较少的费用就可适应欧洲铁路运输企业的各种不同要求.制动系统必须按用户的专门要求来开发.可适配的模块化MBS系统可用于欧洲各国的跨境运输,能满足欧洲不同的安全性规定.系统具有重量轻、所需安装位置小、寿命周期费用低、机车车辆使用率高的优点.Bombardier公司、德国铁路公司、瑞士和奥地利联邦铁路已从中获益. 相似文献
4.
通过理论分析和试验,对欧洲近几年的几种低噪声车轮的设计原理及试验效果做出了评价,对低噪声车轮在货运及高速运输中的应用前景做了分析。 相似文献
5.
我叫大卫·泽洛斯特里克,是斯泰勒工业有限公司的董事长.斯泰勒工业有限公司是美国第一家拉臂钩制造商,成立于1990年,座落于美国爱荷华州的加纳区. 相似文献
6.
W. B. Hou H. Z. Zhang R. F. Chi P. Hu 《International Journal of Automotive Technology》2009,10(2):175-180
The concept design phase is a critical step in auto-body design, as it has a great effect on later design work. This paper
describes the implementation of an auto-body structure design in the early stages of a new auto-body developing program. In
order to reduce the long design period and analysis error that plagues traditional auto-body concept design, an intelligent
CAE system has been successfully developed and implemented based on the UGS NX/API opening platform. This system, the so-called
ACD-ICAE (Auto-body concept design-intelligent computer aided engineering) System that means concept design-intelligent computer
aided engineering system, employs a fully parametrized template method to build the conceptual auto-body geometry model and
FEM model quickly and easily. It also integrates auto-body modeling, analysis and optimization on only one CAD platform via
a parametric variables database. Moreover, all parametric variables are shared and updated in different phases of the ACD-ICAE
System. A wizard User Interface (UI) based on knowledge of auto-body engineering was developed and used in this system. The
procedures implementing the functional diagram of the ACD-ICAE system are also provided. A typical example of a car body concept
design with four doors shows that the ACD-ICAE system is efficient and accurate. 相似文献
7.
P. F. Sweatman P. N. Joubert 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1976,5(3):155-170
Driver steering performance in a simple circular lane-keeping task, as dependent on the directional response characteristics of the vehicle, was measured. Response Surface Methodology models of steering performance are presented. Several canonical variables describe the drivers responses to vehicle changes. Clear-cut optimum vehicle characteristics cannot be determined, but certain combinations of vehicle characteristics are seen to be undesirable for various reasons related to theoretical mechanisms of driver steering control. 相似文献
8.
J. R. Ellis P. L. Read 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1976,5(4):205-219
The paper describes the development, operation and some of the results obtained from a simulation of the steering behaviour of the double bottom articulated vehicle, in particular the effects that arise when certain axles are locked. 相似文献
9.
H. P. Y. Hitch 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1981,10(4):319-332
The state-of-the-art in analysing a number of ground manoeuvring processes on aircraft is described. The mathematical models are as good as the data supplied to them. 相似文献
10.
Fault detection method for electric parking brake (EPB) systems with sensorless estimation using current ripples 总被引:1,自引:0,他引:1
C. W. Lee H. B. Chung Y. O. Lee C. C. Chung Y. S. Son P. Yoon 《International Journal of Automotive Technology》2010,11(3):387-394
A fault detection method with parity equations is proposed in this paper. Due to its low cost implementation, the velocity
of the motor is not measurable in electric parking brake (EPB) systems. Therefore, residuals are not reliable when estimating
the motor velocity with a low-resolution encoder. In this paper, we propose a fault detection method with sensorless estimation
using current ripples that estimates the position and velocity of the motor by detecting periodical oscillations of the armature
current caused by rotor slots. In addition, this method can estimate the position and velocity of the motor with less computational
effort than a state observer. Moreover, the method is less sensitive to motor parameters than model-based estimation methods.
The effectiveness of this method is validated with experimental data, and the simulation results show that various faults
have their own residual patterns. Therefore, we can detect the presence of faults by monitoring the residual signals. 相似文献