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   751篇
  免费   64篇
  国内免费   85篇
电工技术   11篇
综合类   34篇
化学工业   37篇
金属工艺   11篇
机械仪表   71篇
建筑科学   31篇
矿业工程   13篇
能源动力   24篇
轻工业   4篇
水利工程   4篇
武器工业   5篇
无线电   292篇
一般工业技术   39篇
冶金工业   5篇
自动化技术   319篇
  2024年   4篇
  2023年   11篇
  2022年   23篇
  2021年   29篇
  2020年   33篇
  2019年   27篇
  2018年   37篇
  2017年   28篇
  2016年   33篇
  2015年   49篇
  2014年   76篇
  2013年   65篇
  2012年   76篇
  2011年   66篇
  2010年   38篇
  2009年   35篇
  2008年   27篇
  2007年   29篇
  2006年   34篇
  2005年   28篇
  2004年   18篇
  2003年   17篇
  2002年   16篇
  2001年   12篇
  2000年   12篇
  1999年   15篇
  1998年   14篇
  1997年   8篇
  1996年   13篇
  1995年   3篇
  1994年   2篇
  1993年   3篇
  1992年   1篇
  1991年   4篇
  1990年   2篇
  1989年   5篇
  1988年   2篇
  1986年   4篇
  1983年   1篇
排序方式: 共有900条查询结果,搜索用时 15 毫秒
1.
Background/purposeMeasurements of strains in critical components are often required in addition to finite element calculations when evaluating a structure.MethodsThis paper describes how standard optical fibers, bonded to the surface or embedded in a laminate, can measure strain fields along the entire length of the fiber, using the optical backscatter reflectometer.ResultsA strain field measurement can be much better compared to simulations than the more common single point measurements with strain gauges or Bragg Gratings. Changes of the strain field can be related to damage development and can be used for structural health monitoring. Practical aspects of using the fibers are also discussed.ConclusionDistributed Fiber-Optic Sensing was successfully embedded and bonded to a composite joint. Adhesive damage was identified and the strain field agreed well with FE-Analysis.  相似文献   
2.
Sensing, modeling and control for laser-based additive manufacturing   总被引:1,自引:0,他引:1  
Laser-Based Additive Manufacturing (LBAM) is a promising manufacturing technology that can be widely applied to part preparation, surface modification, and Solid Freeform Fabrication (SFF). A large number of parameters govern the LBAM process. These parameters are sensitive to the environmental variations, and they also influence each other. This paper introduces the research work in RCAM on improving the performance of the LBAM process. Metal powder delivery real-time sensing and control is studied to achieve a controllable powder delivery for fabrication of functionally graded material. A closed-loop control system based on infrared image sensing is built for control of the heat input and size of the molten pool in the LBAM process. The closed-loop control results show a great improvement in the geometrical accuracy of the built features. A three-dimensional finite element model is also established to explore the thermal behavior of the molten pool in the closed-loop controlled LBAM process.  相似文献   
3.
通过对导电填料炭黑(CB)进行官能化,在CB表面引入羧基官能团,利用CB表面的羧基等活性官能团与端异氰酸酯基聚氨酯预聚物反应得炭黑接枝水性聚氨酯(CB-g-WPU),采用乳液共混法制备得CB—g-WPU/WPU气敏导电复合材料,并对CB—g-WPU/WPU复合材料的气敏响应行为进行了研究。X射线光电能谱(XPS)、傅立叶变换红外光谱(FTIR)、热重分析(TGA)等分析结果表明聚氨酯接枝到了炭黑表面;SEM分析表明,炭黑经过接枝改性后均匀分散在基体WPU中。该法制备的CB—g-WPU/WPU复合材料逾渗值低、气敏响应度大、响应范围广,是一种综合性能优异的气敏导电复合材料。  相似文献   
4.
周钦青  陈遵德 《计算机工程》2014,(3):258-261,265
为降低视觉传感网络中图像压缩感知算法的计算复杂度,提出一种基于二次规划的网络图像恢复算法。该算法将压缩感知重构中的欠定线性方程组求解问题,转化为有界约束二次规划问题,在此基础上结合阿米霍步长准则,设计一种压缩感知图像恢复算法,通过求解二次规划问题对网络图像数据进行恢复。理论分析和仿真结果表明,与传统图像压缩感知算法相比,该算法可减少约1/3的图像数据恢复运算时间,且图像重构质量提高3 dB~6 dB,有效提高了视觉传感器网络图像恢复算法的实时性。  相似文献   
5.
熊德兰 《现代计算机》2014,(6):61-63,73
全球剖分理论为全球海量遥感影像数据的组织管理和多尺度遥感影像的作物提取和识别提供新的解决思路.结合基于地图分幅扩展的全球剖分模型及其剖分面片的几何特征,阐述剖分遥感影像模板的概念模型和数据模型,提出利用剖分遥感影像模板来提取作物种植面积的处理流程.并给出不同尺度范围提取作物面积适宜选取的剖分级别和影像分辨率。采用高分辨率遥感影像初步尝试对河南省许昌地区小麦种植面积进行提取,通用遥感影像处理软件相比,其精度和速度都有一定的提高.  相似文献   
6.
M.  A.  N.  U. 《Sensors and actuators. B, Chemical》2008,134(1):266-272
The origin of work-function changes induced in polymer/metal structures (polyacrylic acid (PAA), ammonium and sodium polyacrylate) upon ammonia exposure is studied. To understand and explain the mechanism systematic measurements of uncoated and polymer coated metals are performed in Kelvin Probe (KP) setups. Additional data have been acquired through gravimetric and electrochemical experiments (cyclic voltammetry (CV)). The results obtained confirm that the field effect sensitive processes are taking place at the metal/polymer interface and allow their modelling. The intrinsic sensitivity of metallic samples upon ammonia exposure is influenced by the presence of coating polymers, by their ability to sorb water and to keep the metal surface wet or dry.  相似文献   
7.
The growing need for reliable, efficient, high temperature hydrogen and hydrocarbon monitoring has fueled research into novel structures for gas sensing. Metal oxide semiconductor (MOS) devices employing a catalytic metal layer have emerged as one of the leading sensing platforms for such applications, owing to their high sensitivity and inherent capability for signal amplification. The limited operating temperature of such devices employing silicon as the semiconductor has led research efforts to focus on replacing them with devices based on silicon carbide (SiC). More recently, MOS devices having different oxide layers exhibiting improved sensing performance have emerged. Considering the amount of research that has been carried out in this area in recent times, it is important to elucidate the new findings and the gas interaction mechanisms that have been ascribed to such devices, and bring together several theories proposed by different research groups. In this paper we first highlight the needs which have driven research into SiC based field effect hydrogen and hydrocarbon sensors, illustrate the various structures being investigated, and describe the device evolution and current status. We provide several sensing examples of devices that make use of different oxide layers and demonstrate how their electrical properties change in the presence of the gases, as well as presenting the hydrogen gas interaction mechanisms of these sensors.  相似文献   
8.
New energy storage devices such as batteries and supercapacitors are widely used in various felds because of their irreplaceable excellent characteristics. Because there are relatively few monitoring parameters and limited understanding of their operation, they present problems in accurately predicting their state and controlling operation, such as state of charge, state of health, and early failure indicators. Poor monitoring can seriously afect the performance of energy storage devices. Therefore, to maximize the efciency of new energy storage devices without damaging the equipment, it is important to make full use of sensing systems to accurately monitor important parameters such as voltage, current, temperature, and strain. These are highly related to their states. Hence, this paper reviews the sensing methods and divides them into two categories: embedded and non-embedded sensors. A variety of measurement methods used to measure the above parameters of various new energy storage devices such as batteries and supercapacitors are systematically summarized. The methods with diferent innovative points are listed, their advantages and disadvantages are summarized, and the application of optical fber sensors is emphasized. Finally, the challenges and prospects for these studies are described. The intent is to encourage researchers in relevant felds to study the early warning of safety accidents from the root causes.  相似文献   
9.
高光谱图像分类算法通常需要逐点对图像中的像素点进行迭代处理,计算复杂度及并行程度存在较大差异。随着高光谱遥感图像空间、光谱和辐射分辨率的不断提升,这些算法无法满足实时处理海量遥感图像数据的需求。通过分析NPU存储计算一体化模式与遥感图像分类算法的实现步骤,设计低功耗CPU+NPU异构资源计算架构的低秩稀疏子空间聚类(LRSSC)算法,将数据密集型计算转移至NPU,并利用NPU数据驱动并行计算和内置AI加速,对基于机器学习算法的海量遥感数据进行实时分类。受到big.LITTLE计算范式的启发,CPU+NPU异构资源计算架构由8 bit和低精度位宽NPU共同组成以提高整体吞吐量,同时减少图网络推理过程中的能量损耗。实验结果表明,与CPU计算架构和CPU+GPU异构计算架构的LRSSC算法相比,CPU+NPU异构计算架构的LRSSC算法在Pavia University遥感数据集下的计算速度提升了3~14倍。  相似文献   
10.
A series of multi-walled carbon nanotubes/polyurethane (MWNTs/PU) composite conducting dispersoids were prepared via an in situ coupling reaction among linear hydroxyl-terminated polymer diols, 1,6-hexamethylene diisocyanate (HDI) and various chain extenders. The composite conducting thin films were formed by spin-coating and depositing the dispersoids onto comb-like electrode substrates. The resulting structure and the dispersion quality of MWNTs in the dispersoids were examined by means of FTIR, XRD, TEM, SEM and UV-vis analyses. The response of the as-prepared films toward some volatile organic solvent vapors such as benzene, anhydrous ether, acetone and chloroform was evaluated. The experimental results indicated that the composite conducting films constructed by hydroxyl-terminated poly(butadiene-co-acrylonitrile), trimethylolpropane, and MWNTs-OH bear better vapor responsiveness. The dispersion behavior of MWNTs in the dispersoids, types of MWNTs and soft-hard segmental compositions are believed to be closely related with the sensing properties of the films. In particular, the chemical linkage of MWNT-OH with HDI in the PU matrix is expected to improve the dispersivity and further to enhance the sensing properties of the composite sensors. The vapor sensing properties well reveal that these materials have a possibility as a candidate of volatile organic solvent vapor sensors.  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