共查询到17条相似文献,搜索用时 156 毫秒
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[目的]探讨THz技术在农药识别和残留量检测中的应用。[方法]利用太赫兹时域光谱(THz-TDS)技术对2种除草剂丁草胺和异丙甲草胺在室温氮气环境下的THz远红外光谱特性进行测定,并利用菲涅尔公式的数据处理模型求取了其在0.2~2.2 THz波段内的折射率和吸收系数。[结果]2种农药在0.2~2.2 THz波段内分别存在不同的特征吸收峰。尽管2种农药分子结构相似,但其吸收谱和折射率却存在很大差异。[结论]THz-TDS技术在农药微量残留检测方面是可行的,特别是在识别结构较为相似的物质上有较大优势。 相似文献
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太赫兹时域光谱检测农产品中2种酰胺类农药残留研究(摘要)(英文) 总被引:7,自引:0,他引:7
[目的]探讨THz技术在农药识别和残留量检测中的应用。[方法]利用太赫兹时域光谱(THz-TDS)技术对2种除草剂丁草胺和异丙甲草胺在室温氮气环境下的THz远红外光谱特性进行测定,并利用菲涅尔公式的数据处理模型得到其在0.2~2.2THz波段的折射率和吸收系数。[结果]2种农药在0.2~2.2THz波段内分别存在不同的特征吸收峰。尽管2种农药分子结构相似,但其吸收谱和折射率却存在很大差异。[结论]THz-TDS技术在农药微量残留检测方面是可行的,特别是在识别结构较为相似的物质上有较大优势。 相似文献
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针对液体样品在太赫兹光谱检测中遇到的比色皿吸收及频谱振荡问题,以豆油检测为例,在传统计算模型基础上,考虑石英比色皿对THz电磁波吸收,建立THz-TDS技术提取液体材料吸收系数和折射率的计算模型,并对得到的光谱数据利用小波变换进行时-频分析,找出频谱、吸收谱振荡的原因,采用主脉冲截取法,有效去除发射器、探测器以及石英比色皿等光学元件Etalon效应引起的频谱干涉,最后,结合实验得到的0.2~1.8THz波段豆油频谱对采用的主脉冲截取法的优缺点进行分析,并深入探讨1.0~1.8THz频段样品吸收谱、频谱残余振荡存在的原因.该测量分析方法对THz光谱技术在食用油品质检测应用方面进行了有益探索. 相似文献
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[目的]用太赫兹时域光谱技术(THz-TDS)研究三聚氰胺的渡谱特征,以鉴别乳品中是否添加三聚氰胺。[方法]采用THz—TDS技术测量了室温下三聚氰胺和三聚氰酸在0.3~2.5THz的吸收谱和折射率谱。[结果]2种样品在O.3~2.5THz波段各有明显的特征吸收峰,三聚氰胺在1.98和2.24THz,三聚氰酸在1.27和2.37THz,这是用THz—TDS技术进行鉴别的基础。密度泛函理论计算和晶体数据表明,2种样品的THz吸收光谱主要来源于分子间的与氢键相关的集体振动模式。三聚氰胺在该波段的吸收谱,可用于奶粉中不同含量三聚氰胺的定量分析,也可用于研究三聚氰胺和三聚氰酸形成的1:1网状结构。[结论]太赫兹光谱不仅是鉴别三聚氰胺与三聚氰酸的有效手段,而且为研究它们之间的复合物结构提供了新的思路。 相似文献
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我国杂交水稻种植面积十分广泛,种子纯度是种子质量核心指标之一,直接影响杂交水稻的产量.利用透射型太赫兹(Terahertz wave,THz)光谱仪采集16种杂交水稻种子光谱数据,分析其太赫兹光谱频率特征和吸收系数,研究杂交水稻粉末粒度和固定剂浓度对其光谱的影响,结果表明:样品粉末颗粒小于2μm能避免太赫兹波散射对THz光谱数据采集的影响,在样品中添加聚乙烯固定剂不会增加吸收杂波,但能改变吸收强度;在0.1~2THz范围内杂交水稻种子均有不同的特征吸收峰,但少部分品种吸收峰位置靠近,因此直接用杂交水稻种子的THz光谱特征吸收频率识别杂交水稻种子比较困难,需要进一步结合其它方法. 相似文献
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本文对^60Co-γ射线辐照灭菌在灵芝栽培上的应用进行了研究。试验结果表明:利用γ射线对灵芝栽培料进行辐照,可达到满意的灭菌效果,且对菌丝体的生长和提高子实体产量具有明显的促进作用。在本试验条件下,最适辐照剂量为2.8Mrad。 相似文献
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沈国舫 《农业工程技术:农产品加工》2002,(3):26
2.加强高新技术成果在农产品加工中的应用研究 现代高新技术发展日新月异,这些高新技术的研究成果很多可以移植到农产品加工领域,促进加工水平的升级。例如,χ射线检测技术,本来是为检测一些不易拆卸分解的大型构件或机械零件的内部缺陷而开发应用,近来已被成功地移植到农产品加工领域,像软χ射线被成功地运用于瓜果的自动化、无损伤检测分级。…… 相似文献
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Carter SG Birkedal V Wang CS Coldren LA Maslov AV Citrin DS Sherwin MS 《Science (New York, N.Y.)》2005,310(5748):651-653
Semiconductor quantum well electroabsorption modulators are widely used to modulate near-infrared (NIR) radiation at frequencies below 0.1 terahertz (THz). Here, the NIR absorption of undoped quantum wells was modulated by strong electric fields with frequencies between 1.5 and 3.9 THz. The THz field coupled two excited states (excitons) of the quantum wells, as manifested by a new THz frequency- and power-dependent NIR absorption line. Nonperturbative theory and experiment indicate that the THz field generated a coherent quantum superposition of an absorbing and a nonabsorbing exciton. This quantum coherence may yield new applications for quantum well modulators in optical communications. 相似文献
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Ozyuzer L Koshelev AE Kurter C Gopalsami N Li Q Tachiki M Kadowaki K Yamamoto T Minami H Yamaguchi H Tachiki T Gray KE Kwok WK Welp U 《Science (New York, N.Y.)》2007,318(5854):1291-1293
Compact solid-state sources of terahertz (THz) radiation are being sought for sensing, imaging, and spectroscopy applications across the physical and biological sciences. We demonstrate that coherent continuous-wave THz radiation of sizable power can be extracted from intrinsic Josephson junctions in the layered high-temperature superconductor Bi2Sr2CaCu2O8. In analogy to a laser cavity, the excitation of an electromagnetic cavity resonance inside the sample generates a macroscopic coherent state in which a large number of junctions are synchronized to oscillate in phase. The emission power is found to increase as the square of the number of junctions reaching values of 0.5 microwatt at frequencies up to 0.85 THz, and persists up to approximately 50 kelvin. These results should stimulate the development of superconducting compact sources of THz radiation. 相似文献
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Young JM Carruthers GR Holmes JC Johnson CY Patterson NP 《Science (New York, N.Y.)》1968,160(3831):990-991
A rocket-borne photometer has detected far ultraviolet night glow radiations that are identified as Lyman-beta (HI 1026 angstroms), and the helium lines at 304 or 584 angstroms, or at both. At an altitude of 227 kilometers the measured intensity for Lyman-beta was about 10 rayleighs. The discrimination characteristics of the broad-band helium radiation filter give helium line intensities, at 227 kilometers, of 4.8 and 12 rayleighs, respectively, pending identification of the wavelength of the radiation as 304 or 584 angstroms. These ultraviolet radiations appear sufficient to maintain the night E and F(1) regions of the ionosphere. 相似文献
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管振谦 《山西农业大学学报(自然科学版)》1984,(1)
本试验利用激光,r—射线,中子三种辐射类型,照射向日葵种子,从出苗日期,出苗率以及植物学性状的改变,了解这三种物理因素,对向日葵的辐射效应及诱发有益突变的适宜辐射剂量。三种辐射类型照射向日葵播前种子,均表现随剂量的增高,出苗延迟,出苗率降低。辐射对于生长的抑制作用,常随生育期的推移而逐渐消失。不同的品种对辐射的敏感性是有明显差异的,农家品种比墨葵抗辐射。当辐射剂量较高时(如r—射线四万伦,中子5×10~11~1×10~12)常出现顶端生长点破坏,多头,叶片的卷曲撕裂状,这均属于辐射引起的生理及结构的损伤,并不遗传。从各种辐射类型对不同品种,及同一辐射类型不同剂量的辐射效应看,植株生长基本正常的剂量,往往会出现一些性状优良的单株: 钕玻璃激光5次,氮分子激光5分、10分、 r—射线2万伦, 中子5×10~10~1×10~11,可作为向日葵的适宜诱变剂量,从中选出的A_2—38—6突变系,其特点为,早熟,产量超过对照29.7%。 相似文献
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Identification of general properties of evolutionary radiations has been hindered by the lack of a general statistical and phylogenetic approach applicable across diverse taxa. We present a comparative analytical framework for examining phylogenetic patterns of diversification and morphological disparity with data from four iguanian-lizard taxa that exhibit substantially different patterns of evolution. Taxa whose diversification occurred disproportionately early in their evolutionary history partition more of their morphological disparity among, rather than within, subclades. This inverse relationship between timing of diversification and morphological disparity within subclades may be a general feature that transcends the historically contingent properties of different evolutionary radiations. 相似文献
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以大蒜品种'二水早'花序轴离体培养形成的试管苗为材料,用不同剂量60Co-γ射线进行辐照处理,研究了辐照对试管苗增殖、生长及其超氧阴离子(O2- · )产生速率和超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性的影响.结果表明,试管苗在0~16 Gy的辐照剂量范围内均没有死亡,1 Gy以下的辐照剂量对大蒜试管苗生长和抗氧化特性没有显著影响,4 Gy以上的辐照剂量抑制试管苗增殖和生长,抑制程度随着辐照剂量的提高而加强.60Co-γ射线辐照不同程度地影响大蒜试管苗的O2- · 产生速率及SOD、POD和CAT的活性. 相似文献
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"Inordinate Fondness" explained: why are there So many beetles? 总被引:1,自引:0,他引:1
BD Farrell 《Science (New York, N.Y.)》1998,281(5376):555-559
The phylogeny of the Phytophaga, the largest and oldest radiation of herbivorous beetles, was reconstructed from 115 complete DNA sequences for the 18S nuclear ribosomal subunit and from 212 morphological characters. The results of these analyses were used to interpret the role of angiosperms in beetle diversification. Jurassic fossils represent basal lineages that are still associated with conifers and cycads. Repeated origins of angiosperm-feeding beetle lineages are associated with enhanced rates of beetle diversification, indicating a series of adaptive radiations. Collectively, these radiations represent nearly half of the species in the order Coleoptera and a similar proportion of herbivorous insect species. 相似文献