首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   149篇
  免费   1篇
公路运输   30篇
综合类   41篇
水路运输   45篇
铁路运输   9篇
综合运输   25篇
  2022年   3篇
  2021年   3篇
  2020年   2篇
  2019年   5篇
  2018年   12篇
  2017年   12篇
  2016年   12篇
  2015年   5篇
  2014年   7篇
  2013年   16篇
  2012年   7篇
  2011年   5篇
  2010年   10篇
  2009年   9篇
  2008年   5篇
  2007年   2篇
  2006年   10篇
  2005年   11篇
  2004年   2篇
  2003年   1篇
  2002年   2篇
  2001年   3篇
  2000年   3篇
  1983年   1篇
  1981年   1篇
  1972年   1篇
排序方式: 共有150条查询结果,搜索用时 46 毫秒
81.
Skin detection has been considered as the principal step in many machine vision systems, such as face detection and adult image filtering. Among all these techniques, skin color is the most welcome cue because of its robustness. However, traditional color-based approaches poorly perform on the classification of skin-like pixels. In this paper, we propose a new skin detection method based on the cascaded adaptive boosting (AdaBoost) classifier, which consists of minimum-risk based Bayesian classifier and models in different color spaces such as HSV (hue-saturation-value), YCgCb (brightness-green-blue) and YCgCr (brightness-green-red). In addition, we have constructed our own database that is larger and more suitable for training and testing on filtering adult images than the Compaq data set. Experimental results show that our method behaves better than the state-of-the-art pixel-based skin detection techniques on processing images with skin-like background.  相似文献   
82.
泸州港口经济发展的SWOT分析   总被引:1,自引:0,他引:1  
"十一五"期间,是泸州长江"黄金水道"建设的黄金时期,也是泸州港口经济发展的重要战略机遇期.运用SWOT分析方法对泸州港经济发展的内部优势、劣势及外部的机会和挑战进行了全面、系统分析.以求提升泸州港口综合竞争力,探求泸州港口经济发展战略、实现泸州发展战略和打造川南港口经济中心.  相似文献   
83.
“Big data” which admittedly means many things to many people is no longer confined to the realm of technology. Today it is a business imperative and is providing solutions to long-standing business challenges for banking and financial markets companies around the world. Financial services firms are leveraging big data to transform their processes, their organizations and the entire industry. Since 2012, the term “big data” has frequently been mentioned and used to describe and define the huge amount of data in the information explosive era and to name related technological development and innovation. As to the police work, the coming of big data era is not only a challenge but also an opportunity. Police agencies should go with the tide of development to start with such aspects as work thinking, top design, public information sharing and application and talent provision so as to promote the new development and progress of police work. This paper expounds the practical effect and significance of police big data application by cases happened in some areas.  相似文献   
84.
Many mechanical systems have the characteristics of multiple failure modes and complex failure mechanisms. On the basis of stress-strength interference (SSI) model, this paper takes the mechanical system with common cause failure (CCF) as the research object. The relationship between the stress distribution and the strength distribution is studied, and the failures of components are independent of each other under the deterministic stress. Then, the concept of conditional reliability is introduced to build the system reliability models under the action of one-stress and multi-stress for both series and parallel systems. Finally, the corresponding properties of the proposed methods are discussed to show their advantages.  相似文献   
85.
随着汽车碰撞安全法规的不断完善和广大消费者对汽车安全的日益重视,在开发微型轿车时,汽车生产商不能仅局限于符合国家被动安全法规,而应进一步提高安全性能以满足消费者的需求,同时提高自身产品的市场竞争力。介绍了正面碰撞微型轿车乘员约束系统(配置安全气囊)设计开发的一般方法。  相似文献   
86.
87.
Range extender modules are one option to compensate for short drive ranges of electric vehicles. The close interaction of combustion engine and generator poses new challenges in development. A key requirement for range extender systems is to be light and virtually imperceptible in operation. High-speed electrical machines aim at increasing power density. However, their introduction in a range extender requires a gearbox. The combustion engine torque fluctuations can lead to rattle in the gearbox. The rattle can be overcome by a dual mass flywheel. An interdisciplinary model is developed and used to analyse three different range extender systems: one with a low speed generator without gearbox, one with a high-speed generator, and one with a high-speed generator and a dual mass flywheel. The efficiency was found to be higher for the system with a low speed generator, whereas the power density and the costs are beneficial for the high-speed concept. A dual mass flywheel eliminates the changes of torque direction in the gearbox. It reduces the speed fluctuations of the gearbox and generator by over 90 % compared to the low speed setup. But it increases rolling moment and subsequently chassis excitation compared to a setup with only a gearbox.  相似文献   
88.
基于任意欧拉拉格朗日(ALE)方法,忽略流体的粘性,建立水射流冲击刚性平板的数值模型。为了更为精确地捕捉流场中压力波,该文推导了在ALE框架下的间断有限元方法。该方法易于提高数值离散的空间精度,数值稳定性较
  好,利于精确模拟高速水射流冲击过程。对于自由液面的变形,采用径向基函数方法确定网格单元的速度。该方法采用边界网格节点的信息去推导出内部网格节点的信息,不需要单元信息。平头水柱射流冲击的数值结果与Autodyn的数值结果吻合较好。在验证方法合理性的基础上,文中对平头及圆头水柱中压力波的分布特性进行了分析。数值结果表明:当冲击在平板表面时,会在产生一个压力波之后向水域内传播,且使得平板受到较大压力的作用。此外,圆头水柱的射流冲击将会产生一个更大的压力峰值。  相似文献   
89.
Humaninterleukin 18(hIL 18)isanewlyiden tifiedcytokinemainly producedbymonocytesandmacrophages.ThecytokinecaninduceTh1cellstosecreteIFN γ ,IL 2andGM CSF .Itenhancesthecy totoxityofNKandCTLcell,andalsoreducesthelev elofIL 10 .Thus,thereispotentialtherapeuticvalueof…  相似文献   
90.
结合纵梁漏孔检测的具体情况对随机Hough变换加以改进和应用,实现对纵梁图像圆的检测,并减少了随机Hough变换中存在的无效积累问题。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号