全文获取类型
收费全文 | 424篇 |
免费 | 6篇 |
专业分类
公路运输 | 49篇 |
综合类 | 52篇 |
水路运输 | 256篇 |
铁路运输 | 39篇 |
综合运输 | 34篇 |
出版年
2023年 | 15篇 |
2022年 | 4篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 5篇 |
2018年 | 11篇 |
2017年 | 16篇 |
2016年 | 18篇 |
2015年 | 22篇 |
2014年 | 24篇 |
2013年 | 16篇 |
2012年 | 29篇 |
2011年 | 24篇 |
2010年 | 10篇 |
2009年 | 19篇 |
2008年 | 21篇 |
2007年 | 32篇 |
2006年 | 24篇 |
2005年 | 22篇 |
2004年 | 22篇 |
2003年 | 15篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 2篇 |
排序方式: 共有430条查询结果,搜索用时 843 毫秒
141.
142.
Nuno Fonseca Carlos Guedes Soares Ricardo Pascoal 《Journal of Marine Science and Technology》2006,11(4):245-259
An analysis is presented of the vertical bending moments induced in a containership by a set of abnormal waves measured at
different locations and on different occasions. A systematic investigation was carried out by using a large set of wave traces
that included abnormal waves. In this way it was possible to assess the influence of the height, length, and shape of the
abnormal waves on the wave-induced structural loads. The probability distributions of the ship responses to the sea states
that included the abnormal waves were also calculated and were compared to the responses induced by the abnormal waves and
to fitted distributions. Finally, the structural loads induced by the abnormal waves were compared with rule values and with
long-term predictions. 相似文献
143.
探地雷达在路基路面病害检测中亟待解决的问题 总被引:2,自引:0,他引:2
由于路基路面异常体病害探地雷达探测中存在的诸多问题,主要针对地下散射波进行讨论,认识了异常"点元"的电磁波响应特征,通过数值模拟和物理模拟结果来揭示电磁波的叠加原理,只有当异常体上的某个"点元"所形成的散射波被位于其正上方的雷达仪器以首波的形式记录时,该记录点所对应的水平位置才是该"点元"所在的实际位置。 相似文献
144.
To meet the increasing applications of the deepwater steel lazy-wave riser (SLWR), the riser abandonment and recovery (A&R) is a great challenge for SLWR installation and its mechanical analysis is necessary and significant. This paper is focused on the abandonment and recovery process which is of great importance to the installation feasibility and analysis. A comprehensive mechanical model based on the nonlinear large deformation beam theory for simulating the deepwater SLWR is proposed. And a simple and suitable model for analyzing the A&R cable is developed. The presented model with detailed boundary conditions is able to deal with three different A&R methods. Numerical analysis is conducted by the finite difference method to investigate the riser configurations and somev important mechanical parameters of the pipeline and cable which exert influences on the riser's performance and the A&R cable's requirement. Parametric comparison study is conducted to analyze the advantage of different method. The proposed model can help on development of deepwater SLWR A&R design and analysis. 相似文献
145.
通过引入摩擦力与速度关系的近似非线性数学表达式,推导制动工况下机车车辆转向架制动块颤振的分段非线性数学方程.利用Runge-Kutta-Fehlberg(RK45)法,定量分析与研究方程解的性质和制动块颤振的非线性响应,给出随初始速度变化的时间位移曲线、相图和动态分岔图;分析机车制动时振动特性与闸瓦的质量、摩擦特性以及支撑部件刚度等因素的关系.特性分析表明当速度小于0.218 9 m·s-1时系统会出现严重的自激振动,自激振动最大位移随着临界速度的增大而剧增;当速度增大到0.219 6 m·s-1时,系统出现Hopf分岔,从平衡点处分岔出稳定的极限环,振动的幅值较小;当速度大于0.219 6 m·s-1时临界速度对振动的最大位移影响较小,最大位移缓慢地增加. 相似文献
146.
A nonlinear time-domain procedure is presented which is used to calculate the vertical responses of a container ship advancing
in head waves. The method assumes linear radiation forces represented by time convolution of memory functions, infinite frequency
added masses, and radiation restoring coefficients. The nonlinear hydrostatic restoring and Froude–Krilov forces are computed
exactly over the instantaneous wetted surface of the ship's hull. Forces due to green water on deck are calculated using the
momentum method. Nonlinear effects are identified on different vertical ship responses, namely on the heave and pitch motions,
the vertical accelerations, and the vertical bending moment. These non-linear effects are expressed by the variation of the
transfer function with the wave amplitude, the higher-order harmonics of the time signals, the offset of the time series,
and the asymmetry of the peaks. The numerical results and the quantified nonlinear effects are compared with experimental
results showing an ability to reproduce the main nonlinear effects.
Received: December 17, 2001 / Accepted: January 31, 2002 相似文献
147.
This paper deals with stochastic wave models and their influence on wave load modelling of marine structures. The need for more refined theories is underlined for some applications and an entirely new quadratic model for the wave elevation is outlined. Finally, a number of physical phenomena relevant to waves are illustrated which are likely to be important for marine structures and could, in the near future, require ad hoc modelling. 相似文献
148.
船-桥碰撞力学问题研究现状及非线性有限元仿真 总被引:4,自引:0,他引:4
归纳研究了船舶与桥梁碰撞力学的几种典型计算方法,并对各自的特点进行了分析。文中借助DYTRAN非线性有限元程序,以一艘4万吨级的油船与长江上某一斜拉索桥发生正向碰撞为例,演示了有限元法仿真计算船-桥碰撞问题的一般过程。反映了船-桥碰撞过程中船艏、桥梁承合、桥面和拉索的力与变形的时间历程,得到了具有指导意义的结论。 相似文献
149.
150.
沿海内贸集装箱班轮航线优化研究 总被引:1,自引:0,他引:1
随着沿海内贸集装箱运输市场的快速发展,各大班轮公司如何把船舶安排到最佳航线上,使有限的船舶资源创造最大的经济利益,成为各大公司研究的课题。根据沿海几大干线港口之间的运量需求,建立非线性规划与整数规划相结合的混合模型,选择典型航线建立运输网络,并对其进行优化。该数学模型可应用于解决我国沿海内贸集装箱船舶运输航线配置问题,进而实现利润最大。 相似文献