全文获取类型
收费全文 | 507篇 |
免费 | 9篇 |
专业分类
公路运输 | 141篇 |
综合类 | 148篇 |
水路运输 | 109篇 |
铁路运输 | 101篇 |
综合运输 | 17篇 |
出版年
2022年 | 7篇 |
2021年 | 17篇 |
2020年 | 15篇 |
2019年 | 2篇 |
2018年 | 11篇 |
2017年 | 6篇 |
2016年 | 6篇 |
2015年 | 13篇 |
2014年 | 15篇 |
2013年 | 31篇 |
2012年 | 53篇 |
2011年 | 37篇 |
2010年 | 45篇 |
2009年 | 32篇 |
2008年 | 38篇 |
2007年 | 41篇 |
2006年 | 37篇 |
2005年 | 25篇 |
2004年 | 6篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有516条查询结果,搜索用时 31 毫秒
511.
A finite element formulation was presented for the nonlinear free vibration of thin-walled curved beams with non-symmetric open across section. The kinetic and potential energies were derived by the virtual principle. The energy function includes the effect of fiexural-torsional coupling, the torsion warping and the shear centre location. For finite element analysis, cubic polynomials were utilized as the shape functions of the two nodal thin-walled curved elements. Each node possesses seven degrees freedom including the warping degree of freedom. The nonlinear eigenvalue problem was solved by the direct iteration technique. The results are compared with those for straight beams as available in the literature. The results for nonlinear free vibration analysis of curved beams for various radii and subtended angle are presented. 相似文献
512.
Fuhao Mo Shuyong Duan Xiaoqing Jiang Sen Xiao Zhi Xiao Wei Shi Kai Wei 《International Journal of Automotive Technology》2018,19(2):301-312
Objective
With widely usage of restraint system, fatal injuries to occupants have been largely limited while non-fatal lower extremity injuries have not been effectively improved. The present study aims to investigate occupant lower extremity injuries under realistic impact environments.Methods
A biofidelic lower extremity model, a dummy model and a car cab model were combined to set up a realistic impact environment. Three typical frontal impact groups were simulated. Occupant global lower kinematics, long bone axial force and bending moment were presented to in-depth investigate lower extremity injury mechanism and tolerance.Results
Various overlap frontal impacts cause totally different lower extremity kinematics in the combination of structural invasion and restraint system effects. The femur fracture occurred at a small axial force of 7.57 kN combing a substantial bending moment peak of 172 Nm. Ankle joint injuries were found in 100 % and 25 % overlap impacts that present large tibial axial force and joint rotation angle.Conclusions
Overall results indicate that a coupling threshold of femur axial force and bending moment is of rationality to predict global femur fracture. The ankle joint injury occurrence is significantly related to the coupling effects of tibia axial force and excessive self-kinematics.513.
大跨度钢管混凝土拱桥拱肋吊装过程仿真分析 总被引:1,自引:0,他引:1
大跨度钢管混凝土拱桥的拱肋吊装是一个复杂的过程 ,为了保证最终的成桥线形和受力状态满足设计要求 ,需要采用施工控制仿真计算。本文给出了仿真计算的具体步骤 ,提出了基于迭代理论的前进分析方法 ,并通过实例验证了此方法的可行性 相似文献
514.
本文介绍了新开发的船舶防污仿真系统.该系统按照机电一体化的仿真思路,将电气控制界面和机械管路界面相结合,涵盖了船舶防污系统中主要的机械设备和电气设备控制电路,对于培养机电一体的新型船舶管理人员和航海类专业学生有重要意义.该系统已经应用在教学和船员培训中,并取得了良好的效果. 相似文献
515.
516.