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1.
Many composite parts, such as laminated panels and grid-like shells, operate under high mechanical loading. Evaluation of their structural integrity is crucial to ensure the long-lasting operation of critical components. Since testing a structure under full or “proof” load might be dangerous for personnel, it would be preferable to use a remote, rapid inspection technique. This paper describes a practical application of IR thermography to the inspection of large composite parts used in the aerospace industry. This work has used just one cycle of increasing load from zero load to failure, and this was done for both for tensile and compressive loads. It is shown that, during the formation of micro-defects in polymeric composites, about 40 % of the total dissipated energy is expended for material heating, while about 60 % is related to material damage accompanied by an increase in the defect concentration. Non-uniform composite deformation causes temperature anomalies, whose amplitude may reach 1.5–2.5 °C at a load of about 50–60 % of the limit load.  相似文献   
2.
Thermal and infrared imagery creates considerable developments in Non-Destructive Testing (NDT) area. Here, a thermography method for NDT specimens inspection is addressed by applying a technique for computation of eigen-decomposition which refers as Candid Covariance-Free Incremental Principal Component Thermography (CCIPCT). The proposed approach uses a shorter computational alternative to estimate covariance matrix and Singular Value Decomposition (SVD) to obtain the result of Principal Component Thermography (PCT) and ultimately segments the defects in the specimens applying color based K-medoids clustering approach. The problem of computational expenses for high-dimensional thermal image acquisition is also investigated. Three types of specimens (CFRP, Plexiglas and Aluminium) have been used for comparative benchmarking. The results conclusively indicate the promising performance and demonstrate a confirmation for the outlined properties.  相似文献   
3.
智能手机的主要叶类蔬菜品质和新鲜度指标的光谱检测   总被引:2,自引:0,他引:2  
蔬菜品质和新鲜度的高低不仅影响食用时的口感,而且营养程度也不一样。作为蔬菜品质和新鲜度重要参考指标之一的叶绿素和含水量的检测,已经越来越受到国内外学者的重视。相比于传统的肉眼目视判断的检验方法,可见-近红外光谱分析具有快速高效、无损、非接触等独特的优势,更加适合蔬菜的实时检测。目前相关研究主要集中在生长中植被叶绿素和含水量的反演,对市场上成品蔬菜的研究较少,或者研究对象单一,缺乏市场普适性。此外,光谱数据的获取需要专业的光谱仪采集,费时费力,各种生理生化指标的研究离实用化还有很长的距离。为了与实际相结合,基于智能手机光谱系统(SCSS)建立了快速、准确、普适性强的反演蔬菜叶绿素和含水量的模型,并通过地面光谱仪SVC数据验证了该系统的可靠性。选取市场典型的五种蔬菜(菠菜、小油菜、油麦菜、生菜和娃娃菜)作为实验样本,分别进行常温保存和冷藏保存来模拟现实中菜市场和超市的蔬菜储存环境。每隔24 h进行一次数据采集。对获取的原始光谱数据进行波段选择和小波变换去噪的预处理。构建蔬菜叶绿素反演指数(VCRIm, n)和蔬菜含水量反演指数(VWRI(i, j)),分别提取该两个指数与叶绿素和含水量实测值的相关系数R作为权重系数,最终建立了叶绿素和含水量的加权平均反演模型。实验结果表明,SVC仪器和SCSS两者数据针对蔬菜叶绿素和含水量的敏感波段基本一致,叶绿素反演的敏感波段在730~980 nm之间,反演精度R2分别为0.863和0.808 1,标准差为8.679 5和8.892 5;含水量反演的敏感波段在水汽吸收波段950~1 000 nm之间,反演精度R2分别为0.742 9和0.712 9,标准差为8.789 9%和8.861 4%。SVC实验数据跟SCSS实验数据结果十分接近,验证了新型智能手机光谱系统实时监测蔬菜叶绿素和含水量的有效性。智能手机光谱系统具有体积小、价格便宜的优势,结合网络云端服务和实时数据反馈的特点,能够实现蔬菜品质和新鲜度指标的智能检测,让光谱分析真正应用于人们日常生活中。  相似文献   
4.
In order to increase the understanding of soft tissues mechanical properties, 3D Digital Holographic Interferometry (3D-DHI) was used to quantify the strain-field on a cat tympanic membrane (TM) surface. The experiments were carried out applying a constant sound-stimuli pressure of 90 dB SPL (0.632 Pa) on the TM at 1.2 kHz. The technique allows the accurate acquisition of the micro-displacement data along the x, y and z directions, which is a must for a full characterization of the tissue mechanical behavior under load, and for the calculation of the strain-field in situ. The displacements repeatability in z direction shows a standard deviation of 0.062 µm at 95% confidence level. In order to realize the full 3D characterization correctly the contour of the TM surface was measured employing the optically non-contact two-illumination positions contouring method. The x, y and z displacements combined with the TM contour data allow the evaluation its strain-field by spatially differentiating the u(m,n), v(m,n), and w(m,n) deformation components. The accurate and correct determination of the TM strain-field leads to describing its elasticity, which is an important parameter needed to improve ear biomechanics studies, audition processes and TM mobility in both experimental measurements and theoretical analysis of ear functionality and its modeling.  相似文献   
5.
应用X射线显微CT(X-μCT)对正常及骨质疏松大鼠的骨小梁结构进行了分析,并与骨组织形态计量法的测量值进行了比较,探讨了X射线光谱技术在骨结构分析中的应用.实验对大鼠骨样晶进行X-μCT扫描,扫描条件为80 kVp,80 μA,360°旋转,帧平均4帧,角度增益0.4°,分辨率14 μm.三维重建并分析了骨小梁结构,结构参数包括骨体积分数(BV/TV)、骨小梁厚度(Tb.Th)、骨小梁数量(Tb.N)以及骨小梁问隔(Tb.Sp).结果表明,采用X-μCT分析不同组大鼠的骨小梁结构参数值之间存在显著差异(P<0.05),测定值与传统骨组织形态计量法的测定值显著相关,其中胫骨骨小梁BV/TV,Tb.Th,Tb.N,Tb.Sp的相关系数r分别为0.984,0.960,0.995,0.988,腰椎骨小梁各结构参数的相关系数分别为0.938,0.968,0.877,0.951.因此,X-μCT可以较好地呈现并区分正常骨组织、骨质疏松骨组织以及经雌激素治疗后骨组织的微观结构,可以实现对骨小梁结构参数的分析测定,与骨组织形态计量法相比是一种更精确、立体、快速日无损测量骨微结构和评价骨质量的方法.  相似文献   
6.
拉曼光谱技术在中国古玉、古玉器鉴定和研究中的应用   总被引:4,自引:0,他引:4  
激光拉曼光谱技术是应用于科技考古研究中的高技术之一,属于无损分析研究,但作为一种很好的无损分析方法它在中国古代玉器研究中的应用并不非常广泛.文章首先介绍了激光拉曼光谱技术的基本原理及近几年来国内外的最新进展,然后从矿物结构与拉曼特征峰之间的关系入手比较了目前国内外5种常见玉石的激光拉曼研究结果.然后分别通过对浙江良渚遗址和河南安阳殷墟遗址出土的4件中国古代玉器与新疆和田地区出产的软玉样品进行对比研究,成功地利用激光拉曼光谱技术对一批中国古代玉器进行了无损鉴定,从而阐明该项技术在中国古代玉器结构测试和材质鉴定中是一种很好的无损分析研究方法.最后,讨论了目前激光拉曼光谱技术在中国古玉和古代玉器研究中存在的局限性并对其发展前景进行了展望.  相似文献   
7.
利用“管道式合成”方法合成了5种成分相同、结构不同的Ni(OH)2样品.采用X射线衍射(XRD)、场发射扫描电镜表征材料的微观结构及参数.测试了材料的电化学性能,考察了I101/I001比值与Ni(OH)2材料电化学性能的关系.研究结果表明,随I101/I001比值的增大,样品的电化学性能呈下降的趋势.说明XRD峰强比...  相似文献   
8.
为了提高食品的样品检验效率,采用高通量研磨制备样品,利用X射线荧光光谱法对食品中硒含量进行检测。重点研究了样品含水率、样品颗粒粒径、研磨条件、检测条件等因素对检测结果的影响。结果表明:样品干基含水量小于20%,样品颗粒粒径小于100μm;高通量研磨条件为装样量3 g,频率30 Hz,研磨3 min;高精度X射线荧光光谱仪检测条件为检装样量0.2 g,PP膜压紧,检测90 s时的情况下,硒的检出限0.01 mg/kg,仪器的精密度小于5%,与粉碎法进行对比,相对偏差在-10.37%~8.05%。说明高通量研磨-X射线荧光光谱法检测食品中硒含量的方法快速、准确,可以满足批量样品现场检测分析需求。  相似文献   
9.
Consumer-grade digital cameras with or without external filters are recognized as a cost-effective method of vegetation monitoring. These cameras could produce time series information related to biophysical properties of vegetation. This paper evaluates the use of low-cost external filters with digital cameras for assessing vegetation indices (VIs). The system was implemented for ground-based (handheld) remote sensing in assessing biophysical properties of vegetation like plant phenology and Chlorophyll content. It also has high potential for above-canopy measurement using low-altitude remote sensing (LARS). In this study the modified cameras were used to capture near-infrared (NIR), red-edge (RE), and red (R) bands using proposed external filters. We use the low-cost NIR-R and NIR-RE external filters with modified cameras and tested the cameras performance using custom chamber under different illumination. Based on our findings, a method was proposed for enhancing the value of VI, which comprised the extracted DN of two broadbands like NIR and R. New ranges of broadband in red edge area (REhigh and RElow) are proposed as alternative bands in estimating Chlorophyll content. In addition, evaluation and implementation for assessing VIs are detailed in this study.  相似文献   
10.
The performance of a series of 1-amino-2,6-dicyano-3,5-diphenylbenzene derivatives (i.e., meta-terphenyls) as fluorescent molecular probes for monitoring cationic photopolymerization of monomers by the Fluorescence Probe Technique (FPT) was studied. It was found that the m-terphenyls accelerate the cationic photopolymerization initiated with diphenyliodonium photoinitiators at the wavelength where the photoinitiator alone does not work. Consequently, application of the m-terphenyls in a dual role: (a) as fluorescent probes for monitoring the cationic polymerization progress, and (b) as long-wavelength sensitizers for diphenyliodonium photoinitiators is proposed. Next, a precise method for determination of relative sensitization efficiency of the sensitizers has been devised and applied for evaluation of the performance of the m-terphenyl sensitizers in comparison to that of a commercial sensitizer: 2,4-diethyl-9H-thioxanthen-9-one.  相似文献   
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