全文获取类型
收费全文 | 55627篇 |
免费 | 6474篇 |
国内免费 | 3944篇 |
专业分类
电工技术 | 5753篇 |
技术理论 | 3篇 |
综合类 | 5074篇 |
化学工业 | 10939篇 |
金属工艺 | 2201篇 |
机械仪表 | 4179篇 |
建筑科学 | 2672篇 |
矿业工程 | 1617篇 |
能源动力 | 5531篇 |
轻工业 | 2161篇 |
水利工程 | 5210篇 |
石油天然气 | 4139篇 |
武器工业 | 620篇 |
无线电 | 1667篇 |
一般工业技术 | 4614篇 |
冶金工业 | 2950篇 |
原子能技术 | 1477篇 |
自动化技术 | 5238篇 |
出版年
2024年 | 273篇 |
2023年 | 806篇 |
2022年 | 1501篇 |
2021年 | 1789篇 |
2020年 | 1897篇 |
2019年 | 1647篇 |
2018年 | 1534篇 |
2017年 | 1926篇 |
2016年 | 2169篇 |
2015年 | 2225篇 |
2014年 | 3096篇 |
2013年 | 3666篇 |
2012年 | 3780篇 |
2011年 | 4352篇 |
2010年 | 3028篇 |
2009年 | 3286篇 |
2008年 | 3037篇 |
2007年 | 3660篇 |
2006年 | 3455篇 |
2005年 | 3065篇 |
2004年 | 2525篇 |
2003年 | 2250篇 |
2002年 | 1793篇 |
2001年 | 1519篇 |
2000年 | 1284篇 |
1999年 | 1092篇 |
1998年 | 899篇 |
1997年 | 760篇 |
1996年 | 720篇 |
1995年 | 640篇 |
1994年 | 534篇 |
1993年 | 412篇 |
1992年 | 347篇 |
1991年 | 218篇 |
1990年 | 221篇 |
1989年 | 159篇 |
1988年 | 113篇 |
1987年 | 85篇 |
1986年 | 60篇 |
1985年 | 30篇 |
1984年 | 46篇 |
1983年 | 32篇 |
1982年 | 19篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 15篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1959年 | 24篇 |
1951年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
One of the leading time of flight imaging technologies for depth sensing is based on Photonic Mixer Devices (PMD). In PMD sensors each pixel samples the correlation between emitted and received light signals. Current PMD cameras compute eight correlation samples per pixel in four sequential stages to obtain depth with invariance to signal amplitude and offset variations. With motion, PMD pixels capture different depths at each stage. As a result, correlation samples are not coherent with a single depth, producing artifacts. We propose to detect and remove motion artifacts from a single frame taken by a PMD camera. The algorithm we propose is very fast, simple and can be easily included in camera hardware. We recover depth of each pixel by exploiting consistency of the correlation samples and local neighbors of the pixel. In addition, our method obtains the motion flow of occluding contours in the image from a single frame. The system has been validated in real scenes using a commercial low-cost PMD camera and high speed dynamics. In all cases our method produces accurate results and it highly reduces motion artifacts. 相似文献
82.
Communication is a key success factor of distributed software projects. Poor communication has been identified as a main obstacle to successful collaboration. Global projects are especially endangered by information gaps between collaborating sites. Different communication styles, technical equipment, and missing awareness of each other can cause severe problems. Knowledge about actual and desired channels, paths, and modes of communication is required for improving communication in a globally distributed project. However, many project participants know little about communication and information flow in their projects. In this contribution, we focus on knowledge about communication and information flow. It is acquired by modelling on‐going and desired flows of information, including documented and non‐documented channels of information flow. We analyzed a distributed software project from the information flow perspective. Based on the findings, we developed specific techniques to improve information flow in distributed software development according to the FLOW Method. In a second distributed project, we evaluated one of the techniques. We found the FLOW mapping technique to be suitable for effectively spreading knowledge about communication and information flow in global software projects. 相似文献
83.
84.
Time-series primitive static states for detailing work state and flow of human-operated work machine
This paper proposes a quantification method for a comprehensive work flow in construction work for describing work states in more detail on the basis of analyzing state transitions of primitive static states (PSS), which consist of 16 symbolic work states defined by using on-off state of the lever operations and joint loads for the manipulator and end-effector. On the basis of the state transition rules derived from a transition-condition analysis, practical state transitions (PST), which are common and frequent transitions in arbitrary construction work, are defined. PST can be classified into essential state transition (EST) or nonessential state transitions (NST). EST extracts common phases of work progress and estimates positional relations between a manipulator and an object. NST reveals wasted movements that degrade the efficiency and quality of work. To evaluate comprehensive work flows modeled by combining EST and NST, work-analysis experiments using our instrumented setup were conducted. Results indicate that all the PSS definitely changes on the basis of PST under various work conditions, and work analysis using EST and NST easily reveals work characteristics and untrained tasks related to wasted movements. 相似文献
85.
86.
针对目前的网络仿真工具在对软件定义网络(SDN)的仿真过程中,未考虑交换机的处理时延的问题,提出一种处理时延的仿真方法,目的是为了使仿真结果更加真实和准确。该方法首先将交换机的转发处理过程分解为对流表的查询操作和执行不同的动作;然后,利用交换机的处理器频率和访存周期,将查询流表和执行动作转换为处理时间。实验中测量了真实环境中不同配置的交换机处理时延,并与利用该方法仿真出的处理时延进行对比。实验结果表明,利用该方法仿真出的处理时延和真实交换机的处理时延基本一致,该方法能够较准确地仿真交换机处理时延。 相似文献
87.
88.
针对边缘检测中阈值很难确定导致不能准确提取背景边缘信息的问题,提出一种改进的基于边缘信息车流量检测方法。该方法预先对路况边缘图像作削顶处理获取一个恰当的阈值,从而可以准确地提取背景边缘信息;且在车辆计数过程中,结合固定窗法和浮动窗法二者的优点,设计一种新的浮动窗法进行车辆计数。实验结果表明,该方法在实时性、检测速度、正确率等方面得到很大的改进,能够在不同环境下进行正确有效地车流量检测。 相似文献
89.
采用主监视窗扩展技术的增强现实三维注册方法 总被引:1,自引:0,他引:1
在增强现实三维注册中,采用重新检测策略时顿卡现象严重。提出一种采用主监视窗扩展技术的增强现实三维注册方法。在检测阶段,引入特征点可信度和主监视窗,并设计主监视窗的分割、扩展和调控策略,大幅提升了计算速度;在跟踪阶段,采用基于图像金字塔的光流算法进行特征点跟踪。实验证明,该方法不仅有效缓解了顿卡现象,也提升了系统整体的实时性。 相似文献
90.