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   3203篇
  免费   481篇
  国内免费   582篇
电工技术   166篇
综合类   337篇
化学工业   166篇
金属工艺   91篇
机械仪表   672篇
建筑科学   73篇
矿业工程   52篇
能源动力   27篇
轻工业   115篇
水利工程   13篇
石油天然气   22篇
武器工业   47篇
无线电   830篇
一般工业技术   345篇
冶金工业   24篇
原子能技术   117篇
自动化技术   1169篇
  2024年   7篇
  2023年   34篇
  2022年   76篇
  2021年   70篇
  2020年   97篇
  2019年   75篇
  2018年   102篇
  2017年   143篇
  2016年   161篇
  2015年   190篇
  2014年   315篇
  2013年   283篇
  2012年   317篇
  2011年   318篇
  2010年   248篇
  2009年   242篇
  2008年   260篇
  2007年   256篇
  2006年   199篇
  2005年   166篇
  2004年   136篇
  2003年   104篇
  2002年   100篇
  2001年   78篇
  2000年   68篇
  1999年   41篇
  1998年   25篇
  1997年   34篇
  1996年   20篇
  1995年   18篇
  1994年   11篇
  1993年   16篇
  1992年   14篇
  1991年   11篇
  1990年   8篇
  1989年   5篇
  1988年   3篇
  1987年   3篇
  1986年   2篇
  1985年   2篇
  1984年   3篇
  1983年   1篇
  1982年   1篇
  1981年   2篇
  1964年   1篇
排序方式: 共有4266条查询结果,搜索用时 31 毫秒
141.
双目立体视觉传感器的现场标定技术   总被引:2,自引:0,他引:2  
王俊修  孔斌 《计算机工程与应用》2004,40(18):189-191,220
双目立体视觉传感器在机器视觉和三维测量中有着广泛的应用。其中测量精度是一个很重要的因素,尤其是在三维测量中,高测量精度的要求使得传感器的标定显得尤为重要。该文提出了一种双目立体视觉传感器的现场标定方法,不仅提高了标定精度,还避免了离线标定中大量的重复性劳动,同时也研究了摄像机镜头畸变的问题。实验结果表明,此方法能够得到满意的标定精度。  相似文献   
142.
In this paper, we propose a new method for estimating camera motion parameters based on optical flow models. Camera motion parameters are generated using linear combinations of optical flow models. The proposed method first creates these optical flow models, and then linear decompositions are performed on the input optical flows calculated from adjacent images in the video sequence, which are used to estimate the coefficients of each optical flow model. These coefficients are then applied to the parameters used to create each optical flow model, and the camera motion parameters implied in the adjacent images can be estimated through a linear composition of the weighted parameters.We demonstrated that the proposed method estimates the camera motion parameters accurately and at a low computational cost as well as robust to noise residing in the video sequence being analyzed.  相似文献   
143.
王颖  梁峰  李平 《质谱学报》2006,27(Z1):142-143
This application describes the use of LC/Ion Trap MS and LC/TOF for the identification of and quantization of terbutylazine in olive oil samples. The analysis by ion trap was achieved in MS/MS mode, monitoring the characteristic fragment ion at m/z 174. The identification by LC/TOF was accomplishment with accurate mass, along with the accurate mass of chlorine isotope cluster present in terbutylazine. The accuracy typically is better than 2 ppm. The method sensitivity, linearity precision accuracy matrix effect, and limit of detection were also studied.  相似文献   
144.
为解决航空遥感相机检焦系统故障分析、元器件选型及提高检焦精度的问题,本文深入研究了基于Ronchi光栅的光电自准直检焦法。首先,归纳总结了国内外航空相机常用的几种检焦方法,对比了每种检焦方法的优缺点。接着,重点介绍了基于Ronchi光栅的光电自准直检焦系统的构成和工作原理,建立了数学模型,模拟了检焦系统在不同像面位置处的输出波形。然后,为衡量离焦程度,提出了离焦评价因子的概念,接着分析了光学系统的衍射效应和像差大小、Ronchi光栅的周期选择及检焦光源的能量分布这三种因素对检焦精度的影响,给出了Ronchi光栅周期的选择方法。最后,通过实验的方法对本文的仿真结果加以验证。实验结果表明:合焦波形的峰峰值占比0.82,对应0.05 mm步长下的平均检焦分辨力约为10%。  相似文献   
145.
金延国 《衡器》2006,35(5):13-15,22
简要介绍了数字视频监控称重系统的构成、特点及工作原理,论述了利用常用开发工具Delphi、VB编程实现数字视频图像采集的方法。  相似文献   
146.
Optical machines with a vision system containing a video camera are designed to perform contact-less three-dimensional measurements. They are becoming more widely used in the industrial sector because of the many possibilities for automation they permit and because of the speed and economies in measurement tasks that can consequently be obtained. Within dimensional control these machines introduce significant characteristics of flexibility, savings and reliability. Therefore the purpose is to identify the principal metrological characteristics of such machines and so characterise the metrological traceability of the measurements obtained from them. The aim is to qualify each part of the optical machine as well as on the whole. Previously, no metrological traceability of this equipment has been provided in primary metrology, either at national (SIT—Sistema di Taratura in Italia—Calibration System in Italy) or at international level (EA–European co-operation for Accreditation). For this reason we develop a mathematical model that permits the evaluation of the measurement uncertainties in the use of such a device. The purpose is to obtain the certification of the measurement results furnished by the optical machine in as broad a context as possible. The experimental results of the tests are introduced for validating the proposed method. This paper provides the basis of the expression of the uncertainty of a measurement result obtained using the optical measurement machines and it shows the necessary requirements for the numerical evaluation of such uncertainty.  相似文献   
147.
This poem summarizes the fit‐first method of camera evaluation described in Jim Worthey's “Applications of vectorial color.” The algorithm works with the locus of unit monochromats (LUM) in camera and CIE color‐matching spaces. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011;  相似文献   
148.
航空相机是一种重要的机载光电设备,在航空对地测绘等领域有着较为广泛的应用,为方便、直观地对航空相机进行地面检测,设计和实现了一种配套某型航空相机的检测仪系统。根据航空相机地面保障设备任务书和相机与地保设备通讯协议,给出了检测仪系统的功能需求。根据相机的接口要求和系统计算能力的要求,设计了检测仪系统的硬件方案。根据软件部分的功能需求,提出了一种新的分层架构,同时详细论述了软件系统的关键技术,描述了程序的运行流程,给出了检测仪系统的软件设计方案,并在VC6.0环境下实现了检测仪软件系统。针对检测仪的工作方式,设计了测试流程,并根据流程对检测仪进行了详尽的测试,经多次测试,检测仪工作正常。测试结果表明,检测仪系统满足了对其功能的全部要求,运行稳定,操作简便,显示直观,可以应用于航空相机地面保障任务。  相似文献   
149.
The aim of this study was to calculate a reasonable correction factor that could be corrected when the sensitivity of each gamma camera is measured and a whole body bone scan is performed as a follow-up examination. Seven pieces of equipment were used to analyse the sensitivity measurements of each gamma camera based on the source sensitivity measurement method recommended by the IAEA. These were BRIGHTVIEW, PRECEDENCE, ECAM, ECAM signature, ECAM Plus, SYMBIA T2 and INFINIA. The 99mTc line source for the sensitivity measurement was generated in 4–7 kcps, which are the common values in a whole body bone scan. All the cameras were equipped with a low-energy and high-resolution parallel multi-hole collimator and set at a window width and photo peak of 15% and 140 keV, respectively. After placing the 99mTc source as closely as possible to the collimator, the count was measured for 60 and 120 seconds to calculate correction factor. To determine if the correction factor calculated using the 99mTc line source could be applied to a whole body bone scan of a real patient, a whole body bone scan was performed on 27 patients before applying the correction factor for comparative analysis. According to the experimental results using the 99mTc line source, the gamma camera sensitivity was the highest for ECAM plus, followed in order by the gamma cameras, ECAM signature, SYMBIA T2, ECAM, BRIGHTVIEW, INFINIA and PRECEDENCE. When the results were used to calculate the correction factor based on the ECAM gamma camera, which had a medium-degree of sensitivity, the respective correction factors were 1·07, 1·05, 1·03, 1·00, 0·90, 0·83 and 0·72. The correction factors calculated based on the experiment using a 99mTc line source were similar to those calculated based on the whole body bone scan. Clinical application of correction factor for measured sensitivity enables estimation of factor correction depending on difference in equipment when image is read, which improves accuracy and reliability of examination, and is expected to be used especially for continuous follow-up examination.  相似文献   
150.
韩卫萍 《城市建筑》2014,(2):228-228
本文主要讲述何为基于摄像机的交互技术以及如何在展演建筑中使用该交互技术,使展项更富有感染力和趣味性,使参观者更容易融入其中。  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