半导体发光二极管(LED)的应用及发展前途     

夏继军  江仁杰 《湖南农机》2007,(5):11-12

半导体二极管(LED)是应用最为广泛的电子元件之一,本文介绍了半导体二极管(LED)的发光原理、特性、分类、检测、应用及发展前景。  相似文献   

信息审计的内容框架分析   总被引：1，自引：0，他引：1  

任玉珍 《农业网络信息》2009,(7):119-121

信息审计已经成为信息管理的一种重要手段,是制定组织战略前期的一个重要步骤.在对国外研究的基础上,首先对信息审计的内涵进行了界定,然后从信息图谱和信息管理流程两个角度分别对信息审计的内容进行了分析,提出了两个内容框架模式.最后,指出了目前信息审计所面临的问题和挑战.  相似文献   

激光光致发光光谱分析系统的设计及应用     

杨琴  田永红 《长江大学学报》2009,(4)

在微区紫外-可见阴极荧光分析系统成功研制的基础上,采用532nm固体激光器作为激发源研制了一套计算机自动控制的微区光致发光分析系统。该系统不仅可探测可见波段的激光光致荧光,并且将荧光的研究波段扩展至红外区域。对来自于不同地区金刚石样品的900～1010nm波段红外光致发光光谱进行探测,结果发现不同样品在946nm、957nm左右2个宽峰处呈现不同光谱特征,能有效地对样品的生长条件和受外界影响等因素进行分析和研究。该分析系统能在更宽的波段上获取更多更新的样品内在信息,为样品的测试提供了一种有效方法。  相似文献   

黄瓜等作物广谱营养液的遴选     

余允贵  杨玉爱 《浙江大学学报(农业与生命科学版)》1998,(2)

采用最适吸收范围内的离子组合、制成营养液为拟广谱营养液，与科威特Ａｔａｒ黄瓜营养液、欧洲茄子、甜椒营养液，日本园试配方营养液作互比试验．结果表明：该营养液栽培黄瓜，分别比科威特Ａｔａｒ黄瓜配方、日本园试配方增产１５％，旺收期分别提前１５天和２～３天；栽培茄子，产量与欧洲茄子配方相似，但旺收期提前７天；栽培甜椒比欧洲甜椒配方增产３０％，旺收期提前１２天．表现出明显的早熟、优质和高产的特征．在该配方中加１ｍｍｏｌ／Ｌ铵态氮也完全适合秋黄瓜的无土栽培．  相似文献   

Prediction of watermelon quality based on vibration spectrum     

《Postharvest Biology and Technology》2013

Judging watermelon quality based on its apparent properties such as size or skin color is difficult. A non-destructive method is employed here, based on vibrational response spectrum, to determine the quality indices of watermelon (Charleston gray). The responses of samples to vibration excitation were recorded by laser Doppler vibrometry (LDV). The phase shift between input and output signals were extracted over a wide frequency range. The total soluble solids (TSS), titratable acidity (TA) and TSS/TA ratio also measured as watermelon quality characters. Stepwise multiple linear regression (SMLR) as well as partial least square regression (PLS) was applied to extracted vibration spectrums to construct prediction models of watermelon quality. The results showed that performance of SMLR models were better than PLS. The determination coefficients (R²) of SMLR validation models were 0.9976, 0.9985 and 0.9542 for TSS, TA and TSS/TA respectively. It is likely that reduction of cell wall materials to soluble solids during ripening process changes viscoelastic properties of watermelon reflected by vibrational response. This study demonstrated the feasibility of mentioned method for predicting the quality of watermelons in an industrial grading system.  相似文献   

广东康禾自然保护区植物区系研究   总被引：1，自引：0，他引：1  

林中大 《广西林业科学》2007,36(2):75-77,81

根据对保护区的植被调查,分析了该保护区的植物区系、生活型谱和植被类型,结果显示该保护区植物区系组成以泛热带和热带亚洲成分最为丰富,各占30.5%和13.8%;生活型谱以高位芽植物占绝对优势,但比例略低于近纬度带的阴那山等地区;植被类型主要为亚热带常绿阔叶林,但因人为破坏较严重,现有植被主要为次生性较强的常绿阔叶林和针阔叶混交林。  相似文献   

红树植物地面反射光谱特征研究   总被引：1，自引：1，他引：1  

翁强  卢昌义 《福建林业科技》2006,33(3):14-19

结合使用野外便携式光谱仪对九龙江口红树林保护区白骨壤、秋茄、桐花树3种红树植物的叶冠表观光谱的测量结果,系统分析比较了红树植物叶冠反射光谱特征及其差异;并在一个潮间带底质遥感信息处理平台上对研究地点进行基于表观光谱特征的白骨壤和秋茄的SPOT卫星遥感图像分类;最后讨论了红树光谱研究中存在的问题。  相似文献   

三羟鹅膏毒肽的反相高效液相色谱分离纯化     

曹福祥  张志光  梁宋平 《中南林业科技大学学报(自然科学版)》2003,23(2):43-45

用反相高效液相色谱法,以0.02mol醋酸铵-乙腈为流动相和梯度洗脱模式,从灰花纹鹅膏菌中分离纯化出三羟鹅膏毒肽(amanin),产品纯度达96%以上,三羟鹅膏毒肽的分子量为903.3.  相似文献   

Power spectrum density and experimental modal analysis of wide belt sander applied in domestic wood industry     

Zheng Wang  Dianxiang Zhu 《Frontiers of Forestry in China》2007,2(3):350-354

This paper took the upper-lower wide belt sander B229 with four-feet wide belts, manufactured in China, as the study target. By means of framework dynamic design, we study its vibration characteristics by commencing from the place having horizontal defects and used experimental modal analysis (EMA) and power spectrum density (PSD) to observe the sanding parts and the whole machine, respectively. In the modal test, we mainly adopted the cross spots testing method to get the frequency response function of the fixed spots to every excitation vibration spot, then applied the SISO frequency response function and the frequency response function fitting method to identify and complete parameter recognition, respectively. The typical frequency response function chart of the whole machine and its sanding parts, as well as its second-order mode charts of contacting roller, were obtained. Through PSD analysis, we can get the amplitude-frequency spectrum and drive frequency. Translated from Scientia Silvae Sinicae, 2005, 41(6): 132–137 [译自: 林业科学]  相似文献   

Wood Moisture Content Measurement by X-Ray Exposure Method     

尚德库 《林业研究》1997,8(1):54-58

lNTRoDUCTIONTheon-sitcnon-dcstructit'cmcasurcl11cntofu.oodmoisbocontcntattTactsgrcatintcrcsts.Itpla3'simpor-tantpartsinthescicntificrcscarchsucl1asonthchcatandmasstransportproccssesint"ooddri'ing.thcim-pregnationofliquidinxt'ood.thcmoisturccontcntdistri-b…  相似文献