全文获取类型
收费全文 | 2981篇 |
免费 | 158篇 |
专业分类
公路运输 | 802篇 |
综合类 | 845篇 |
水路运输 | 476篇 |
铁路运输 | 657篇 |
综合运输 | 359篇 |
出版年
2024年 | 10篇 |
2023年 | 17篇 |
2022年 | 70篇 |
2021年 | 102篇 |
2020年 | 125篇 |
2019年 | 67篇 |
2018年 | 79篇 |
2017年 | 95篇 |
2016年 | 102篇 |
2015年 | 123篇 |
2014年 | 251篇 |
2013年 | 164篇 |
2012年 | 316篇 |
2011年 | 300篇 |
2010年 | 199篇 |
2009年 | 181篇 |
2008年 | 168篇 |
2007年 | 227篇 |
2006年 | 211篇 |
2005年 | 121篇 |
2004年 | 52篇 |
2003年 | 49篇 |
2002年 | 34篇 |
2001年 | 22篇 |
2000年 | 8篇 |
1999年 | 11篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1990年 | 3篇 |
1988年 | 2篇 |
排序方式: 共有3139条查询结果,搜索用时 125 毫秒
91.
92.
文章采川三维有限元数值模拟研究了偏压连拱隧道不同施工顺序下拱顶下沉、中墙稳定性及初期支护受力特征.研究结果表明,先开挖浅埋侧时,拱顶沉降较小,中墙在施工中的稳定安全系数较大、弯矩较小,初期支护受力较大;对于浅埋偏压连拱隧道,围岩变形及中墙在施工中的稳定性控制更为重要.所以,从有利于围岩变形、中墙稳定性控制以及中墙受力的角度出发,宜采用先开挖浅埋侧的施工方法. 相似文献
93.
94.
95.
文章对岜肯隧道浅埋偏压段洞口施工中出现的塌方及初衬开裂情况进行客观分析,结合施工实际提出了地表加固及平衡土体偏压措施,有效地控制了地表变形及隧道沉降开裂,保证了隧道施工安全、顺利进行。 相似文献
96.
97.
文中介绍一种以磁应力为原理的检测技术,即磁力断层摄影检测技术.该技术是一种非接触式的被动检测技术,可以检测出长输管道管体各类型缺陷.首先简单阐述了检测原理,其次详细说明了执行一次检测的全流程工作步骤,以及各步骤的工作内容,然后简要介绍了其独特的经验性计算MAOP和剩余寿命的公式,接着以实际试点检测工作为例,说明了该技术的可行性,最后指明了该技术的优缺点. 相似文献
98.
Conflict detection (CD) is one of the key functions used to ensure air transport safety and efficiency. In trajectory-based operation (TBO), aircraft are provided with more flexibility in en route trajectory planning and more responsibility for self-separation. The high flexibility in trajectory planning enables random changes in pilot intent, thus increasing the uncertainty in trajectory prediction and CD. This study proposes a novel probabilistic CD approach for TBO in which the uncertainty of pilot intent is taken into account by quantifying the aircraft reachable domain constrained by the flight plan. First, a probabilistic model for aircraft trajectory prediction is developed using the truncated Brownian bridge method. Based on this model, a novel conflict probability estimation method is developed. Finally, the performance of the proposed probabilistic CD approach is demonstrated through an illustrative air traffic scenario. 相似文献
99.
For existing advanced geological forecasting, the forecast distance is short and the test frequency is high, increasing test and construction risks. Since various methods have different requirements for the test environ-ment, preparation work can be tedious and result in a long construction time thereby affecting normal construction.A new advanced geological forecast technique based on multi-source seismic interferometry for tunnels is proposed.This technique uses the blast at one end of tunnel as a centrum and receives the signal at the other end of the tun-nel, therefore allowing advanced geological forecasting of the unexcavated tunnel part by relative processing and im-aging. A numerical simulation of this kind of geological forecasting using the finite difference method to simulate two kinds of unfavorable geological bodies (karst and a fault) predicted them accurately and verified the effective-ness and accuracy of this geological forecasting method. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
100.
Water bursts during tunnel construction endanger construction, and it is therefore necessary to reserve a waterproof dike with the required thickness to avoid water bursts and to take reinforcement of the dike and treatment of the structure liable to trigger a water burst. Using the water burst at K5+398 of the Mingyueshan tunnel of the Shanghai-Chengdu expressway as an example, and considering the type of tunnel section and the upright mudstone of the dike, the waterproof dike at the work face is simplified as a round thin plate. A formula for the calculation of a minimum safety thickness for the critical waterproof dike is deduced by analyzing the force applied on the water-proof dike, and the minimum safety thickness for the water burst section at K5+398 of the Mingyueshan tunnel is cal-culated. The numerical simulation analysis demonstrates the critical thickness of waterproof dike at K5+398 of the Mingyueshan tunnel is 1.4-1.55 m, and the calculated water inflow and water burst basically agree with the actual condition. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献