全文获取类型
收费全文 | 321篇 |
免费 | 1篇 |
专业分类
公路运输 | 47篇 |
综合类 | 74篇 |
水路运输 | 72篇 |
铁路运输 | 56篇 |
综合运输 | 73篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 12篇 |
2017年 | 11篇 |
2016年 | 21篇 |
2015年 | 20篇 |
2014年 | 32篇 |
2013年 | 16篇 |
2012年 | 12篇 |
2011年 | 15篇 |
2010年 | 26篇 |
2009年 | 10篇 |
2008年 | 19篇 |
2007年 | 18篇 |
2006年 | 21篇 |
2005年 | 11篇 |
2004年 | 17篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 9篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1990年 | 2篇 |
排序方式: 共有322条查询结果,搜索用时 15 毫秒
261.
The accuracy and time scale invariance of value-at-risk (VaR) measurement methods for different stock indices and at different confidence levels are tested. Extreme value theory (EVT) is applied to model the extreme tail of standardized residual series of daily/weekly indices losses, and parametric and nonparametric methods are used to estimate parameters of the general Pareto distribution (GPD), and dynamic VaR for indices of three stock markets in China. The accuracy and time scale invariance of risk measurement methods through back-testing approach are also examined. Results show that not all the indices accept time scale invariance; there are some differences in accuracy between different indices at various confidence levels. The most powerful dynamic VaR estimation methods are EVT-GJR-Hill at 97.5% level for weekly loss to Shanghai stock market, and EVT-GARCH-MLE (Hill) at 99.0% level for weekly loss to Taiwan and Hong Kong stock markets, respectively. 相似文献
262.
文章以一汽大众2018款迈腾B8L2.0TSI轿车为例,分析电动车窗系统电路,并结合一起真实的故障案例,诊断分析出故障原因,为汽车类似的系统故障诊断分析提供一定的参考。 相似文献
263.
对船舶自动识别系统AIS(Automatic Identification System)消息类型及标准消息格式进行了简要介绍,提出了基于PC机环境下的信息处理模型,并在C Builder开发环境下用Winsock编程对AIS消息的传输进行了实现.这一信息处理模型可为AIS消息处理的研究提供一实验平台. 相似文献
264.
介绍了基于PDA平台的LY05型机车语音录音装置的地面分析软件的设计,以及机车语音录音文件的FTP下载、分析、回放、查询的设计与实现.重点分析比较了PDA与PC机上语音录音文件分析处理过程的异同.该软件的使用促进了机车故障分析的时校性. 相似文献
265.
文章以某连续刚构桥为例,利用结构分析软件MIDAS CIVIL建立了地震响应计算分析模型,并结合时程分析法对该桥的地震响应进行计算分析,所得结果可为大跨径连续刚构桥的抗震设计提供依据。 相似文献
266.
文章以在建的某斜拉桥为实例,结合ANSYS重启动功能及参量瞬变命令,编制了基于真实初始静平衡状态下及斜拉索Eep时效改变下的地震动几何非线性时程响应通用求解程序,并与以初始索力为计算依据的斜拉索Eep时效不变状态下的计算结果进行了对比分析,得出拉索弹性模量时效改变对斜拉桥抗震性能的影响规律,为大跨斜拉桥地震响应的合理计算分析和抗震设计提供参考。 相似文献
267.
268.
269.
Grahama Currie Tony Richardson Dianne Vella-Brodrick Karen Lucas Jenny Morris John Stanley 《Research in Transportation Economics》2010,29(1):287-295
This paper updates results of an international study aimed at quantifying the links between transport disadvantage (TD), social exclusion (SE) and well-being (WB) in Melbourne, Australia. The study extends knowledge associated with SE and transport by quantify social and behavioural implications of lack of public and private transport and the nature of the social WB benefits associated with improving services.Study aims and methodology are outlined. Recent findings covered relate to car ownership on the urban fringe, patterns of transport disadvantage, the analysis of time poverty related to transport disadvantage, measuring the economic value of additional mobility and use of a Structural Equation Model (SEM) to relate WB and SE to TD and a series of explanatory factors.Overall results suggest that those without a car on the urban fringe adjust well with their circumstances by living close to activity centres. They demonstrate sustainable choices, trading off budgets and home location to balance mobility and accessibility. Poorer households with high car ownership value mobility and cheaper more remote fringe dwellings but demonstrate numerous strategies to reduce high car costs which are acknowledged as a significant burden. Analysis identifies 4 key types of transport disadvantage including a ‘vulnerable/impaired’ group which should be of much greater concern for targeted policy than others due to poor scoring on SE and WB scales. The economic value of new mobility is also explored with results suggesting $AUD 20 per average new trip which is four times larger than conventional values for generated travel.Analysis has also suggested that transport disadvantage can relate to socially advantaged as well as socially disadvantaged groups through time poverty. This was found to be an important mitigating factor when relating TD to WB. A statistically reliable structural equation model is developed suggesting the SE-WB link is strong (−.87) with a modest link between TD-SE (.27).Areas for future research in the project are also summarised. 相似文献
270.