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Chemical Bond and Spectral Effect of Rare Earth Compound Crystals
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作者 高发明 张思远 《Journal of Rare Earths》 SCIE EI CAS CSCD 1993年第3期186-190,共5页
The chemical bond parameters and ionic polarizabilities in complex crystals are calculated.The mechanism of host influence on the nephelauxetic effect and hypersensitive transition is discussed.
关键词 Rare earths Chemical bond spectral effect
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Plasmonic gold nanoshell induced spectral effects and refractive index sensing properties of excessively tilted fiber grating 被引量:2
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作者 Binbin Luo Huafeng Lu +4 位作者 Shenghui Shi Mingfu Zhao Jiao Lu Yajie Wang Xin Wang 《Chinese Optics Letters》 SCIE EI CAS CSCD 2018年第10期9-13,共5页
We demonstrate a fiber refractive index(RI) sensor based on an excessively tilted fiber grating(ExTFG)immobilized by large-size plasmonic gold nanoshells(GNSs). The GNSs are covalently linked on ExTFG surface.Ex... We demonstrate a fiber refractive index(RI) sensor based on an excessively tilted fiber grating(ExTFG)immobilized by large-size plasmonic gold nanoshells(GNSs). The GNSs are covalently linked on ExTFG surface.Experimental results demonstrate that both the intensity of the transverse magnetic(TM) and transverse electric(TE) modes of ExTFG are significantly modulated by the localized surface plasmon resonance(LSPR) of GNSs due to the wide-range absorption band. The wavelength RI sensitivities of the TM and TE modes in the low RI range of 1.333–1.379 are improved by ~25% and ~14% after GNSs immobilization, respectively, and the intensity RI sensitivities are ~599%/RIU and ~486%/RIU, respectively. 展开更多
关键词 RIU TM TE Plasmonic gold nanoshell induced spectral effects and refractive index sensing properties of excessively tilted fiber grating
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Nonlinear spectral cleaning effect in cross-polarized wave generation
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作者 Linpeng Yu Yi Xu +5 位作者 Fenxiang Wu Xiaojun Yang Zongxin Zhang Yuanfeng Wu Yuxin Leng Zhizhan Xu 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第5期281-286,共6页
The underlying mechanism of the spectral cleaning effect of the cross-polarized wave(XPW) generation process was theoretically investigated. This study shows that the spectral noise of an input spectrum can be remov... The underlying mechanism of the spectral cleaning effect of the cross-polarized wave(XPW) generation process was theoretically investigated. This study shows that the spectral noise of an input spectrum can be removed in the XPW generation process and that the spectral cleaning effect depends on the characteristics of the input pulses, such as the chirp and Fourier-transform-limited duration of the initial pulse, and the modulation amplitude and frequency of the spectral noise. Though these factors codetermine the output spectrum of the XPW generation process, the spectral cleaning effect is mainly affected by the initial pulse chirp. The smoothing of the spectrum in the XPW generation process leads to a significant enhancement of the coherent contrast. 展开更多
关键词 nonlinear optics cross-polarized wave generation spectral cleaning effect
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Estimating the site effects in Luoyang basin using horizontal-to-vertical spectral ratio method from a short-period dense array 被引量:3
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作者 Yujuan Tan Yunhao Wei +1 位作者 Yonghong Duan Fuyun Wang 《Earthquake Science》 CSCD 2018年第5期272-280,共9页
The influence of local site effects on seismic ground motions is an important issue in seismic hazard assessment and earthquake resistant design. Determining site effects in densely populated cities built on basins ca... The influence of local site effects on seismic ground motions is an important issue in seismic hazard assessment and earthquake resistant design. Determining site effects in densely populated cities built on basins can help to reduce the earthquake hazard. Site effects of Luoyang basin are estimated by the horizontal-to-vertical spectral ratio(HVSR) method using ambient noise records from a short-period dense array. The sites in Luoyang basin are sorted into three types according to the pattern of the HVSR curves. There are cases with a single clear peak, two clear peaks, and an unclear low frequency peak or multiple peaks, which correspond to there being one large impedance contrast interface, two large interfaces, and a moderate one beneath the sites, respectively. The site effects characterized by fundamental frequency from HVSR curves are affected by underlying sedimentary layers and depth of sedimentary basement. According to our results, the existence of thick sediment layer obviously lowers the fundamental frequency to the period range from 2 to 4 s in the downtown area of Luoyang city. The ground motion will amplify when through the sites and the buildings with height of 20–50 floors can resonate at the similar frequency domain. Site effects estimation using HVSR method from a short-period dense array is an effective technique in areas of moderate seismic risk where strong motion recordings are lacking, such as the Luoyang basin. 展开更多
关键词 site effects horizontal to vertical spectral ratio dense array Luoyang basin
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EQUIVALENT CIRCUIT OF NONLINEAR EFFECT OF SPECTRAL IP
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作者 He, Jishan Li, Daqing Tang, Jingtian(Department of Geology, Central South University of Technology, Changsha 410083) 《中国有色金属学会会刊:英文版》 EI CSCD 1995年第3期1-7,共7页
EQUIVALENTCIRCUITOFNONLINEAREFFECTOFSPECTRALIP¥He,Jishan;Li,Daqing;Tang,Jingtian(DepartmentofGeology,Central... EQUIVALENTCIRCUITOFNONLINEAREFFECTOFSPECTRALIP¥He,Jishan;Li,Daqing;Tang,Jingtian(DepartmentofGeology,CentralSouthUniversityof... 展开更多
关键词 spectral IP nonlinear effect EQUIVALENT circuit ADMITTANCE anode/cathode polarizaTion
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Analytical Studies of the Cloud Droplet Spectral Dispersion Influence on the First Indirect Aerosol Effect 被引量:5
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作者 解小宁 刘晓东 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2013年第5期1313-1319,共7页
Atmospheric aerosols (acting as cloud condensation nuclei) can enhance the cloud droplet number concentration and reduce the cloud droplet size, and in turn affect the cloud optical depth, as well as the cloud albed... Atmospheric aerosols (acting as cloud condensation nuclei) can enhance the cloud droplet number concentration and reduce the cloud droplet size, and in turn affect the cloud optical depth, as well as the cloud albedo, and thereby exert a radiative influence on climate (the first indirect aerosol effect). In this paper, based on various relationships between cloud droplet spectral dispersion (c) and cloud droplet number concentration (Nc), we analytically derive the corresponding expressions of the cloud radiative forcing induced by changes in the cloud droplet number concentration. Further quantitative evaluation indicates that the cloud radiative forcing induced by aerosols for the different ^-Nc relationships varies from -29.1% to 25.2%, compared to the case without considering spectral dispersion (e = 0). Our results suggest that an accurate description of e - Nc relationships helps to reduce the uncertainty of the first indirect aerosol effect and advances our scientific understanding of aerosol-cloud-radiation interactions. 展开更多
关键词 spectral dispersion cloud radiative forcing the first indirect aerosol effect
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Degradation of effective carrier-power-to-noise densityratio based on code trackingspectral sensitivitycoefficient for GNSS radio frequencycompatibilityin C band
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作者 刘美红 战兴群 牛满仓 《Journal of Beijing Institute of Technology》 EI CAS 2014年第3期413-419,共7页
The frequency band between 5 010 MHz and 5 030 MHz allocated as C band has been used as a candidate in the global navigation satellite systems (GNSS) along with more and more naviga- tion services in L band. The pot... The frequency band between 5 010 MHz and 5 030 MHz allocated as C band has been used as a candidate in the global navigation satellite systems (GNSS) along with more and more naviga- tion services in L band. The potential benefits and technical requirements of C band for satellite navi- gation have been analyzed before. However the degradation of effective carrier-power-to-noise densi- ty ratio( A (C/No )eu) based on code tracking spectral sensitivity coefficient( CT_SSC ) as a compati- bility assessment methodology for potential GNSS radio frequency compatibility in C-Band has not been discussed clearly. So the compatibility of the signals in the C band between BeiDou (BD) B1 C and GPS L1C, L1C/A, Galileo E1Os as the interoperability or classical signals in L band is analyzed. Simulation results reveal the interference degree between BD III B1C and GPS L1C/A, L1C, Galileo E1OS. The results can also reveal that the multiplexed binary offset carrier (MBOC) and binary phase shift keying (BPSK) modulation is not appropriate for C band. 展开更多
关键词 degradation of effective carrier-power-to-noise density ratio code tracking spectral sen-sitivity coefficient compatibility
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Ripple-effect analysis for operational architecture of air defense systems with supernetwork modeling 被引量:5
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作者 Zhigang Zou Fuxian Liu +2 位作者 Shiman Sun Lu Xia Chengli Fan 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2014年第2期249-264,共16页
In order to solve the problem that the ripple-effect analy- sis for the operational architecture of air defense systems (OAADS) is hardly described in quantity with previous modeling approaches, a supernetwork model... In order to solve the problem that the ripple-effect analy- sis for the operational architecture of air defense systems (OAADS) is hardly described in quantity with previous modeling approaches, a supernetwork modeling approach for the OAADS is put for- ward by extending granular computing. Based on that operational units and links are equal to different information granularities, the supernetwork framework of the OAADS is constructed as a “four- network within two-layer” structure by forming dynamic operating coalitions, and measuring indexes of the ripple-effect analysis for the OAADS are given combining with Laplace spectral radius. In this framework, via analyzing multidimensional attributes which inherit relations between operational units in different granular scales, an extended granular computing is put forward integrating with a topological structure. Then the operation process within the supernetwork framework, including transformation relations be- tween two layers in the vertical view and mapping relations among functional networks in the horizontal view, is studied in quantity. As the application case shows, comparing with previous modeling approaches, the supernetwork model can validate and analyze the operation mechanism in the air defense architecture, and the ripple-effect analysis can be used to confirm the key operational unit with micro and macro viewpoints. 展开更多
关键词 operational architecture air defense system super-network model Laplace spectral radius ripple-effect analysis.
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NONLINEAR EFFECT OF THE DUALFREQUENCY IP SPECTRUM 被引量:2
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作者 He Jishan Li Daqing Tang Jingtian(Department of Geology,Central South University of Technology,Changsha 410083) 《中国有色金属学会会刊:英文版》 EI CSCD 1995年第4期1-7,共7页
NONLINEAREFFECTOFTHEDUALFREQUENCYIPSPECTRUMHeJishan;LiDaqing;TangJingtian(DepartmentofGeology,CentralSouthUn... NONLINEAREFFECTOFTHEDUALFREQUENCYIPSPECTRUMHeJishan;LiDaqing;TangJingtian(DepartmentofGeology,CentralSouthUniversityofTechnol... 展开更多
关键词 nonlinear effect spectral CURVES SAWTOOTH FEATURE dualfrequency IP method
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Spectral Structures of Eu^(2+) in ABF_4 and A_2SiF_6 (A=Na,K,Rb,Cs)
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作者 石春山 满石清 孙家跃 《Journal of Rare Earths》 SCIE EI CAS CSCD 1991年第1期35-38,共4页
The phosphors of ABF_4:Eu^(2+)and A_2SiF_6:Eu^(2+)(A=Na,K,Rb,Cs)have been synthesized,and the crystallographic data obtained accord with ASTM.In these materials,the f→f sharp lines emissions of Eu^(2+) were observed.... The phosphors of ABF_4:Eu^(2+)and A_2SiF_6:Eu^(2+)(A=Na,K,Rb,Cs)have been synthesized,and the crystallographic data obtained accord with ASTM.In these materials,the f→f sharp lines emissions of Eu^(2+) were observed.The coordination numbers of Eu^(2+)in both NaBF_4 and Na_2SiF_6 hosts are less than 8. 展开更多
关键词 spectral structure of Eu^(2+) Nephelauxetic effect Complex fluoride Coordination number PHOSPHOR
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核用锆合金管氧化过程中光谱发射率特性研究
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作者 张凯 桂康 +1 位作者 叶林 刘若语 《传感器与微系统》 CSCD 北大核心 2024年第10期66-70,共5页
发射率在锆合金管非接触测温的准确性和失水事故情况下的传热分析上具有重要意义。本文采集了SZA4、SZA6和ZIRLO 3种锆合金在400,500,600℃下氧化100min过程中4~12μm内的光谱发射率数据,分析了温度、氧化膜厚度和合金组分对材料光谱发... 发射率在锆合金管非接触测温的准确性和失水事故情况下的传热分析上具有重要意义。本文采集了SZA4、SZA6和ZIRLO 3种锆合金在400,500,600℃下氧化100min过程中4~12μm内的光谱发射率数据,分析了温度、氧化膜厚度和合金组分对材料光谱发射率特性的影响规律。结果表明,3种锆合金在氧化过程中发射率变化趋势基本相同,但组分差异导致在发射率的数值和振荡特性上略有差别。通过建立薄膜干涉模型,解释了光谱发射率在波长方向上的振荡现象,并结合振荡极值与干涉效应原理计算了合金表面氧化膜厚度,在0.6~8μm范围内测量精度达到±0.3μm。 展开更多
关键词 锆合金 光谱发射率 氧化膜 干涉效应
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藤黄属植物笼状呫吨酮类化学成分与抗肿瘤作用研究进展
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作者 张俊艳 张倩 金颖慧 《中国药业》 CAS 2024年第7期128-128,I0001-I0005,共6页
目的为藤黄属植物中笼状呫吨酮类化合物与抗肿瘤作用的研究提供参考。方法以“藤黄属”“笼状呫吨酮”“化学成分”“抗肿瘤作用”为关键词,采用计算机检索中国知网和PubMed数据库中1995年至2023年的相关文献,总结藤黄属植物中分离出的... 目的为藤黄属植物中笼状呫吨酮类化合物与抗肿瘤作用的研究提供参考。方法以“藤黄属”“笼状呫吨酮”“化学成分”“抗肿瘤作用”为关键词,采用计算机检索中国知网和PubMed数据库中1995年至2023年的相关文献,总结藤黄属植物中分离出的笼状呫吨酮类化合物的化学成分和抗肿瘤作用。结果笼状呫吨酮类化合物为藤黄属植物的特征性化学成分,取代基主要有异戊烯基、异戊二烯基、羧基、羟甲基、甲氧基、羟基等,具有抗肿瘤、抗菌、抗炎等作用,其中抗肿瘤活性研究最广泛。结论笼状呫吨酮类化合物的合理开发和利用可为天然抗肿瘤化合物的筛选提供参考。 展开更多
关键词 藤黄属 笼状呫吨酮 化学成分 波谱学特征 抗肿瘤作用
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Balmer H_α,H_β and H_γ Spectral Lines Intensities in High-Power RF Hydrogen Plasmas 被引量:1
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作者 王松柏 雷光玖 +1 位作者 刘东平 杨思泽 《Plasma Science and Technology》 SCIE EI CAS CSCD 2014年第3期219-222,共4页
Hα(Balmer-alpha), Hβ (Balmer-beta) and Hγ (Balmer-gamma) spectral line inten- sities in atomic hydrogen plasma are investigated by using a high-power RF source. The intensities of the Hα, Hβ and Hγ spectra... Hα(Balmer-alpha), Hβ (Balmer-beta) and Hγ (Balmer-gamma) spectral line inten- sities in atomic hydrogen plasma are investigated by using a high-power RF source. The intensities of the Hα, Hβ and Hγ spectral lines are detected by increasing the input power (0-6 kW) of ICPs (inductively coupled plasmas). With the increase of net input power, the intensity of Hα im- proves rapidly (0-2 kW), and then reaches its dynamic equilibrium; the intensities of Hβ can be divided into three processes: obvious increase (0-2 kW), rapid increase (2-4 kW), almost constant (4-6 kW); while the intensities of Hγ increase very slowly. The energy levels of the excited hydro- gen atoms and the splitting energy levels produced by an obvious Stark effect play an important role in the results. 展开更多
关键词 Keywords: high-power RF (radio frequency) source ICPs (inductively coupled plasmas) and spectral lines intensity Boltzmann distribution law Stark effect transitionprobability
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基于电子鼻技术的臭灵丹草指纹图谱建立及谱效关系研究
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作者 张逸婷 李争艳 +4 位作者 余晓玲 陆兔林 张欣蕊 赵景祎 谢辉 《中药材》 CAS 北大核心 2024年第2期383-389,共7页
目的:基于超快速气相电子鼻技术,建立15批臭灵丹草饮片的气味指纹图谱,结合谱效相关性分析,筛选与抗氧化活性相关的成分。方法:使用超快速气相电子鼻建立15批臭灵丹草饮片的气味指纹图谱,进行相似度评价。结合AroChemBase数据库进行定... 目的:基于超快速气相电子鼻技术,建立15批臭灵丹草饮片的气味指纹图谱,结合谱效相关性分析,筛选与抗氧化活性相关的成分。方法:使用超快速气相电子鼻建立15批臭灵丹草饮片的气味指纹图谱,进行相似度评价。结合AroChemBase数据库进行定性分析。以DPPH自由基、ABTS自由基清除能力为指标评价臭灵丹草饮片挥发性成分的抗氧化活性,结合多元统计分析评价谱效关系,筛选与抗氧化活性关联度较大的成分。结果:建立了15批臭灵丹草饮片的气味指纹图谱,结合AroChemBase数据库标定了14个共有峰,分别为异戊烷、乙叉降冰生烯、α-蒎烯、α-水芹烯、1,8-桉叶素、5-甲基-4-壬烯、柠檬烯、二溴氯丙烷、芳樟醇、甲基丁香酚、十一酸甲酯、β-石竹烯、醋酸十一酯、覆盆子酮。臭灵丹草饮片挥发油清除DPPH、ABTS自由基的IC50分别为6.56~21.26 mg/mL、3.89~18.34 mg/mL,灰色关联度分析及偏最小二乘回归分析结果表明柠檬烯、甲基丁香酚、覆盆子酮等与其抗氧化相关性较大。结论:臭灵丹草饮片超快速气相电子鼻气味指纹图谱结合谱效关系研究初步筛选了与抗氧化能力相关性较大的3个成分,可为臭灵丹草饮片质量控制提供依据。 展开更多
关键词 臭灵丹草 超快速气相电子鼻 抗氧化 指纹图谱 谱效关系
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多维度评价及优化黄芪瞬时高温灭菌工艺
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作者 时晓宇 焦连庆 +3 位作者 于敏 田义新 焦安妮 栾依琳 《中国农业科技导报》 CAS CSCD 北大核心 2024年第7期223-233,共11页
为优化黄芪瞬时高温灭菌(high temperature short time,HTST)工艺参数并多维度考察其对黄芪质量的影响,基于指标相关性的权重系数(criteria importance though intercrieria correlation,CRITIC)法采用正交设计优化黄芪灭菌工艺参数,以... 为优化黄芪瞬时高温灭菌(high temperature short time,HTST)工艺参数并多维度考察其对黄芪质量的影响,基于指标相关性的权重系数(criteria importance though intercrieria correlation,CRITIC)法采用正交设计优化黄芪灭菌工艺参数,以灭菌温度、灭菌时间、药材粉碎粒度为考察因素,以灭菌率、5种化合物含量及1,1-二苯基-2-苦基肼自由基(1,1-diphenyl-2-picrylhydrazyl,DPPH·)清除率为考察指标,通过直观及方差分析评价灭菌对3个考察指标的影响;并运用液质联用技术(liquid chromatography-mass spectrometry,LC-MS)确认指纹图谱共有峰的结构,以偏最小二乘回归分析法分析共有峰与抗氧化活性的谱效关系。结果显示,灭菌温度是具有显著影响的因素(P<0.05),最佳灭菌工艺参数为灭菌温度(170±2)℃,灭菌时间5 s,粉碎粒度50目;按优化工艺灭菌后的3批样品微生物水平均符合药典规定,5种化合物含量及DPPH·清除率与灭菌前比较无明显变化;灭菌前后指纹图谱相似度均大于0.900;谱效学分析相关性结果与化合物单体抗氧化的试验结果及其结构特点基本一致。综上所述,瞬时高温灭菌对黄芪中微生物具有明显杀灭作用且对其质量无明显影响,表明该方法适用于黄芪药材灭菌。 展开更多
关键词 黄芪 瞬时高温灭菌 指标相关性权重系数 正交设计 谱效关系
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不同灯光新型光谱反射诱虫设备诱杀黄曲条跳甲效果研究
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作者 孔令娟 俞艳 +1 位作者 王连华 黄俭 《长江蔬菜》 2024年第16期69-72,共4页
新型光谱反射诱虫设备利用昆虫视觉识别,可减少施药量及对环境的不良影响,延缓害虫产生抗药性,在生产中具有较高的推广价值。本研究比较了不同灯光(黑光和白光)新型光谱反射诱虫设备和单用黄色诱虫板对黄曲条跳甲的诱集效果。结果表明,... 新型光谱反射诱虫设备利用昆虫视觉识别,可减少施药量及对环境的不良影响,延缓害虫产生抗药性,在生产中具有较高的推广价值。本研究比较了不同灯光(黑光和白光)新型光谱反射诱虫设备和单用黄色诱虫板对黄曲条跳甲的诱集效果。结果表明,不同灯光(黑光和白光)新型光谱反射诱虫设备处理的诱虫量均高于单用黄色诱虫板处理,其中黑光光谱诱虫设备处理对黄曲条跳甲的诱集效果最好,较白光光谱诱虫设备处理的诱虫量提高18.7%,较单用黄色诱虫板处理的提高47.25%,较单用对照黄色诱虫板处理的提高145.2%。白光光谱诱虫设备处理的诱虫量较单用黄色诱虫板处理的提高24.1%,较单用对照黄色诱虫板提高106.6%。不同灯光(黑光和白光)新型光谱诱虫设备在田间放置10~16 d后进入黄曲条跳甲最佳诱捕期,可及早发现和控制黄曲条跳甲为害;诱杀有效期4周左右。 展开更多
关键词 黄曲条跳甲 新型光谱粘虫设备 诱集效果
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生、醋柴胡UPLC-DAD指纹图谱建立及抗肝纤维化作用的谱效关系研究 被引量:1
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作者 陈妮平 王燕 +4 位作者 董妍 肖扬鑫 涂济源 刘艳菊 周仲实 《中国药理学通报》 CAS CSCD 北大核心 2024年第6期1145-1152,共8页
目的建立生、醋柴胡的指纹图谱,比较生、醋柴胡化学成分差异,考察两者抗肝纤维化作用的差异,探究其与抗肝纤维化药效之间的关联性。方法采用UPLC法建立10批生柴胡和10批醋柴胡的指纹图谱,以TGF-β诱导肝星状细胞(LX-2)建立肝纤维化体外... 目的建立生、醋柴胡的指纹图谱,比较生、醋柴胡化学成分差异,考察两者抗肝纤维化作用的差异,探究其与抗肝纤维化药效之间的关联性。方法采用UPLC法建立10批生柴胡和10批醋柴胡的指纹图谱,以TGF-β诱导肝星状细胞(LX-2)建立肝纤维化体外细胞模型,以Ⅰ型胶原蛋白(collagenⅠ,col1a1)和α-平滑肌肌动蛋白(α-smooth muscle actin,α-SMA)蛋白表达情况为药效指标,利用MetaboAnalyst 5.0网站,以变量重要性投影(VIP)值>1为标准筛选影响生、醋柴胡质量的差异标志物,并采用正交偏最小二乘判别分析(OPLS-DA)研究生、醋柴胡差异化学成分及与抗肝纤维化作用的谱效关系,筛选生、醋柴胡抗肝纤维化作用的主要成分。结果生、醋柴胡样品的UPLC指纹图谱共有峰有18个,生、醋柴胡的主要差异成分有9个,其中峰9、7、6可以指认为柴胡皂苷d、柴胡皂苷a、柴胡皂苷f。药效结果发现,生、醋柴胡均有抗纤维化活性,且醋柴胡抗纤维化活性更强。通过谱效关联结果发现,柴胡抗肝纤维化作用的主要相关成分为11、12、14、15、18号峰。结论建立生、醋柴胡的指纹图谱方法简单可行,通过谱效关系筛选出抗肝纤维化活性的重要成分,为明确生、醋柴胡抗肝纤维化作用物质基础提供依据。 展开更多
关键词 生柴胡 醋柴胡 指纹图谱 肝纤维化 正交偏最小二乘 谱效关系
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Spectral Feature Analysis of Semiconductor Thin Disk Laser 被引量:1
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作者 (HE Chun-feng1, QIN Li2, LI Jun1, CHENG Li-wen1, LIANG Xue-mei1, NING Yong-qiang2, WANG Li-jun2 1. Key Laboratary of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences,Changchun 130033, China Graduate School of the Chinese Academy of Sciences, Beijing 100049, China 2. Key Laboratary of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033,China.) 《光机电信息》 2007年第12期19-25,共7页
The semiconductor thin disk laser is a new type of semiconductor laser. This work gives the basic operation function of the semiconductor disk laser, and analyses the heat effect by the experimentally measured photolu... The semiconductor thin disk laser is a new type of semiconductor laser. This work gives the basic operation function of the semiconductor disk laser, and analyses the heat effect by the experimentally measured photoluminescence spectrum of the laser chip at different pump power and different temperatures. We can see that: with increasing pump power, the thermal effect of the gain material becomes seriously and causes the saturation of carrier lifetime, so the electron-hole pair created in the absorbtion layer has no enough time to rate to one of the wells, and the non-radiative recombination happens in the barrier. When the thermal effect becomes stronger, the chip will be not lasing. This phenomenon is from the smaller energy offset between barrier and quantum well. We optimize the original structure design and experimental technology. A non-absorbing AlGaAs layer which is transparent to the pumping and laser wavelength is added to confine the carriers in the quantum wells. At the same time a DBR with double reflecting band is induced to improve the absorbing efficiency of the pumping light. The single QW is replaced by the three narrow QWs. This three QWs structure can add the quantum state of QW, increase the recombination probability of carriers in the QWs and reduce the heat effect. The chemical etching equipment is also improved to control the surface unevenness to be within 50 nm. 展开更多
关键词 thin disk laser heat effect PL spectrum active region heat removal GAIN BARRIER spectral shift
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SH波斜入射下水平成层场地地震动特性研究
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作者 陈三红 张郁山 郝明辉 《震灾防御技术》 CSCD 北大核心 2024年第1期88-95,共8页
基于位移场理论和传递矩阵法,建立SH波斜入射下水平成层场地非线性地震反应等效线性化求解方法,研究SH波不同角度入射下场地地表峰值加速度放大系数及反应谱谱比变化规律。研究结果表明,地震波入射角度对场地地表峰值加速度影响明显,在... 基于位移场理论和传递矩阵法,建立SH波斜入射下水平成层场地非线性地震反应等效线性化求解方法,研究SH波不同角度入射下场地地表峰值加速度放大系数及反应谱谱比变化规律。研究结果表明,地震波入射角度对场地地表峰值加速度影响明显,在大多数情况下,地震波斜入射下地表峰值加速度大于垂直入射;地震波斜入射下反应谱特性变化明显,入射角度对高频段反应谱的放大效应显著,且入射角度对不同类型场地的影响周期范围不同,入射角度对Ⅲ类场地周期影响范围明显宽于Ⅱ类场地。 展开更多
关键词 SH波 斜入射 反应谱谱比 放大效应
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能量色散X射线荧光光谱技术在土壤重金属分析中的应用研究现状
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作者 蒋奡松 吴龙华 李柱 《岩矿测试》 CAS CSCD 北大核心 2024年第4期659-675,共17页
伴随着城市化和工业化的进程,重金属通过各种途径进入生态环境并在土壤中大量富集,对土壤环境健康造成潜在风险。近年来随着能量色散X射线荧光光谱技术(ED-XRF)的发展,仪器的检出限明显降低,并能适用于土壤中各类重金属的检测,正逐渐成... 伴随着城市化和工业化的进程,重金属通过各种途径进入生态环境并在土壤中大量富集,对土壤环境健康造成潜在风险。近年来随着能量色散X射线荧光光谱技术(ED-XRF)的发展,仪器的检出限明显降低,并能适用于土壤中各类重金属的检测,正逐渐成为测定土壤环境中重金属浓度的有效设备。然而,土壤基质的复杂性和仪器自身的限制会导致利用ED-XRF在测定目标重金属时存在准确度和精密度较低等问题。譬如土壤样品的类型及粒径、仪器和环境中的噪声均会对检测造成一定影响,同时在定量分析模型方法的建立上也存在一定难度,仍不能很好地应用于实验室等数据质量要求较高的环境。本文总结了XRF在土壤重金属检测领域的应用与研究进展,探究了不同土壤样品状态及检测条件对ED-XRF仪器检测精确性的影响,梳理了ED-XRF光谱的主要预处理方法以及定量分析模型的建立过程,分析了ED-XRF在评估土壤重金属有效性上的应用潜力。当前,应用于ED-XRF检测的土壤样品制备程序已经相对成熟,在操作手段上如何减少土壤基体效应的影响,学者们的意见相对统一,即尽量使用干样、低粒径或压片土壤样品,而对检测数据的处理和分析还存在一定优化的空间。因此,目前主流的关注领域是结合不同算法的优点,进行ED-XRF光谱的预处理分析及建立定量分析模型来提高ED-XRF检测的精准度。但当下针对不同类型土壤的ED-XRF检测研究只点明了存在差异的现象,对其中的机理尚缺明晰的探究。未来需要继续探明不同基体效应存在于各类型土壤的原因及其影响大小,优化完善ED-XRF光谱定量分析模型,是ED-XRF定量分析研究的两个重要方向,通过多元回归分析对土壤中重金属有效性进行预测研究亦应是今后重点关注的领域。 展开更多
关键词 X射线荧光光谱 重金属 影响因素 光谱解析 定量模型 有效性
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