全文获取类型
收费全文 | 289篇 |
免费 | 5篇 |
专业分类
公路运输 | 75篇 |
综合类 | 101篇 |
水路运输 | 77篇 |
铁路运输 | 29篇 |
综合运输 | 12篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 4篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 8篇 |
2014年 | 4篇 |
2013年 | 6篇 |
2012年 | 22篇 |
2011年 | 11篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 18篇 |
2003年 | 21篇 |
2002年 | 38篇 |
2001年 | 11篇 |
2000年 | 31篇 |
1999年 | 25篇 |
1998年 | 4篇 |
1997年 | 11篇 |
1995年 | 3篇 |
1994年 | 9篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有294条查询结果,搜索用时 15 毫秒
111.
本文针对已抽取海岸边缘特征并二值化的电子海图和已进行任意实数倍缩小变换至海图比累积误差代替门限序列的粗精搜索间隔采样快速实时匹配。通过计算机仿真,证明该算法简便易行、精度较高、实时性好。 相似文献
112.
本文结合上海市崇明县崇西水闸底板的施工 ,介绍大体积混凝土的施工方案及质量控制 ,包括 :生产设备的配置 ,原材料的选择、浇筑方案的制定以及施工现场管理和养护方法等 相似文献
113.
分析了8K型机车监控装置双主机和显示器的使用及存在的一些问题,并针对这些问题可能造成的隐患提出了解决的方案。指出了使用单片机智能化设计,以保证系统工作稳定可靠。同时给出了方案的整体试验结果和结论。 相似文献
114.
Simulation of the oil spill processes in the Sea of Japan with regional ocean circulation model 总被引:1,自引:0,他引:1
Sergey M. Varlamov Jong-Hwan Yoon Naoki Hirose Hideyuki Kawamura Ken Shiohara 《Journal of Marine Science and Technology》1999,4(3):94-107
A simulation of the movement of spilled oil after the incident of the Russian tanker Nakhodka in the Sea of Japan, in January 1997, was performed by a particle tracking model incorporating advection by currents, random
diffusion, the buoyancy effect, the parameterization of oil evaporation, biodegradation, and beaching. The currents advecting
spilled oil were defined by surface wind drift superposed on the three-dimensional ocean currents obtained by the Geophysical
Fluid Dynamics Laboratory modular ocean model (GFDL MOM), which was forced by the climatological monthly mean meteorological
data, or by the European Center for Medium Range Weather Forecasts (ECMWF) daily meteorological data, and assimilated sea
surface topography detected by satellite altimeter. A number of experiments with different parameters and situations showed
that the wide geographical spread of oil observed is not explained by wind drift alone, and that including the simulated climatological
currents gives better results. The combination of surface wind drift and daily ocean currents shows the best agreement between
the model and observations except in some coastal areas. The daily meteorological effect on the ocean circulation model results
in a stronger variability of currents that closely simulates some features of the nonlinear large-scale horizontal turbulent
diffusion of oil. The effect of different parameterizations for the size distribution of model oil particles is discussed.
Received for publication on July 26, 1999; accepted on Nov. 17, 1999 相似文献
115.
A finite difference method based on the Euler equations is developed for computing ship waves and wave resistances. Time
marching is carried out using a time-splitting fractional-step method. The second-order central difference is used to discretize
the spatial differentials, while the convection terms are discretized by the QUICK scheme. A body- and free-surface-fitted
grid system with a cell-centered stencil is used. A Poisson equation for the pressure increment at each time step is solved
to enforce mass conservation. The method is validated by comparing the numerical results with the experimental data for a
Wigley parabolic hull. The characteristics of ship waves, such as the wave profile along the hull, the wave pattern on the
free surface, the pressure distribution on the hull surface, and the wave-making resistance are reasonably predicted. The
calculated results are in good agreement with the experimental data.
Received for publication on Oct. 13, 1998; accepted on Jan. 20, 1999 相似文献
116.
During the installation operations of underwater structures, offshore structures such as semisubmersibles, the steady nonlinear
hydrodynamic force due to the ocean current, the tidal current, and the hydrodynamic interaction between structures are regarded
as major disturbances. Generally, it is difficult and very expensive to collect information about these disturbances in advance,
although such knowledge would be important and necessary for precise installation. Because of this situation, we have proposed
a learning tracking controller (LTC) for automated tracking/docking operations of offshore structures. The LTC can be operated
without any information about current, and can be applied to the installation problem of flexible structures whose flexibility
cannot be ignored. In order to confirm the effectiveness of the LTC, basin tests were carried out using experimental models
with an unknown current. Two types of basin experiment were executed using an ultrasound ranging system and thrusters. One
was trajectory tracking of a semisubmersible, and the other was the precise mating of flexible underwater structures. In both
cases the LTC showed good performance, and in the latter case in particular, two flexible models were successfully made to
track the given trajectory and dock to the docking targets with an accuracy of ±5 mm, after the trajectory had been tracked
six to seven times for learning purposes. No elastic responses were excited in the flexible model.
Received for publication on Dec. 1, 1999; accepted on March 13, 2000 相似文献
117.
A finite-volume method was applied to a simulation of the flow about the sail system of IACC sailing boats. The interface
boundary technique was employed to generate a proper grid system for the two-sails system, which is composed of head and main
sails. The turbulence model was carefully chosen by numerical test, and the most reliable simulation method was completed
and used to design the sails. The suitability of the method is demonstrated by some examples of design applications.
Received for publication on March 14, 2000; accepted on March 16, 2000 相似文献
118.
Hiroharu Kato Tomoaki Iwashina Masaru Miyanaga Hajime Yamaguchi 《Journal of Marine Science and Technology》1999,4(4):155-162
The time-averaged velocity and turbulence intensity distributions were measured by a laser Doppler velocimeter in a turbulent
boundary layer filled with microbubbles. The void fraction distribution was also measured using a fiber-optic probe. The velocity
decreased in the region below 100 wall units with an increase in bubble density. This led to a decrease in the velocity gradient
at the wall, which was consistent with a decrease in shearing stress on the wall. The turbulence intensity in the buffer layer
increased at a low microbubble density, and then began to decrease with an increasing microbubble density. Based on the present
measurements, the mechanism of turbulence reduction by microbubbles is discussed and a model is proposed.
Received for publication on Dec. 3, 1999; accepted on April 18, 2000 相似文献
119.
刘志永 《铁道标准设计通讯》2015,(4):41-44,48
乌鲁木齐集装箱中心站是《中长期铁路网规划》规划建设的18个铁路集装箱中心站之一,如何有效节约用地、减少土方工程,是平面布置的关键。根据三坪车站既有概况,结合乌鲁木齐铁路枢纽总图规划,从运营条件及运营管理、远期发展条件、与城市道路衔接条件和工程条件与投资等多方面,对提出的3个方案进行论证,最终推荐横列式布置方案。合理的平面布置形式,旨在为填方量较大的场站提供参考。 相似文献
120.
高粘着利用机车的系统设计 总被引:2,自引:0,他引:2
孙翔 《西南交通大学学报》1994,29(3):235-248
本文指出,机车的高粘着利用是一个系统工程问题,文中由粘着牵引力的基本概念出发,从机械系统、动力与传动系统、控制系统等不同的方面阐述了高粘着利用机车的设计要求及方法,并从系统工程的角度论证了各部分合理匹配与协调。希望能对提高我国机车的设计水平起到一定作用。 相似文献