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Extraction Condition Optimization and Identification of Phenols from Lonicerae flos
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作者 GAO Wei LI Lang +2 位作者 YU Lian-fang DING Hui-juan DING Sheng-hua 《Agricultural Science & Technology》 CAS 2024年第3期21-30,共10页
Polyphenols were obtained from the natural dried Lonicerae flos by ultrasound-assisted extraction with ethanol as the solvent.Single factor experiment and response surface methodology were employed to optimize the ext... Polyphenols were obtained from the natural dried Lonicerae flos by ultrasound-assisted extraction with ethanol as the solvent.Single factor experiment and response surface methodology were employed to optimize the extraction conditions.Ultra-performance liquid chromatrography(UPLC)-tandem mass spectrometry(MS/MS)was employed to identify polyphenols based on the plant widely targeted metabolomics database in a qualitative and quantitative manner.The results showed that the optimal extraction conditions for total phenols from Lonicerae flos were ultrasound-assisted extraction with a solid-to-liquid ratio of 10∶1 g/mL and 57%ethanol at 70 W and 60°C for 11 min.The yield of total phenols extracted under the optimal conditions reached 71.08 mg/g.The phenols in Lonicerae flos were mainly chlorogenic acid isomers,and the flavonoids were mainly nobiletin,galuteolin,and homoarbutin. 展开更多
关键词 Lonicera flos Total phenols Ultra-performance liquid chromatrography(UPLC)-tandem mass spectrometry(MS/MS) Response surface methodology PHENOLS
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Bi-normalized response spectra and scalar periods for developing uniform seismic design spectra 被引量:3
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作者 徐龙军 谢礼立 《Journal of Southeast University(English Edition)》 EI CAS 2007年第2期266-271,共6页
Aiming at the uniform features of acceleration response spectra, two scalar periods-the response spectral predominant period Tp and the smoothed spectral predominant period To are employed to normalize the abscissa of... Aiming at the uniform features of acceleration response spectra, two scalar periods-the response spectral predominant period Tp and the smoothed spectral predominant period To are employed to normalize the abscissa of the normalized response spectra (NRS) of ground motions, respectively. Engineering characteristics of 5% -damped NRS, and the bi-normalized response spectra (BNRS) are investigated accounting for the effects of soil condition and fault distance. Nearly 600 horizontal ground motion components during the Chi-Chi earthquake are included in the analysis. It shows that the NRS strongly depends on soil condition and fault distance. However, soil condition and distance have only a slight influence on two kinds of BNRS. Dispersion analysis indicates that such normalization can reduce scatter in the derivation of response spectral shapes. Finally, a parametric analysis of the scalar periods (Tp, To) is performed and then compared with those of previous studies. These special and particular aspects of earthquake response spectra and scalar periods need to be considered in developing earthquake-resistant design criteria. 展开更多
关键词 ground motion normalized response spectrum bi-normalized response spectra scalar period
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Generation of artificial earthquakes for matching target response unsmooth spectrum via wavelet package transform 被引量:2
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作者 彭康 王泽伟 孙晶晶 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第8期2612-2617,共6页
The seismic records of target response spectrum used in the time-history analysis should be allowed to meet the norms. However, the previous fitting methods of target spectrum are mostly for the situations that the ta... The seismic records of target response spectrum used in the time-history analysis should be allowed to meet the norms. However, the previous fitting methods of target spectrum are mostly for the situations that the target spectrum is a smooth curve. In many cases, it needs to match unsmooth target spectrum for single determined response spectrum. An adjustment of time history via wavelet packet transform was presented, which is able to fit unsmooth target spectrum. It was found that there is a certain bias between the band center frequency of the component of seismic record after wavelet packet decomposition and the peak frequency of response spectra of wavelet packet components. For this reason, five strategies were presented to select iteration points, and the effects of the five strategies were compared with two calculation examples. It was turned out that the peak frequency of the response spectrum of wavelet packet component can lead to good fitting effect when it is selected as the iteration point. In the iteration process, it shows great promise in fitting non-smooth target spectrum and has a trend of converge. 展开更多
关键词 time history acceleration wavelet packet transform spectral matching peak frequency of response spectrum
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High-level Stark Effect and Spectrum of Spherical Nanometer System 被引量:1
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作者 吴强 龙晓霞 郑瑞伦 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2010年第5期608-614,622,共8页
In the electric field and layer-to-layer interaction energy, the law of split-level of high-level Stark effect of spherical nanometer system is explored as well as the frequency of spectrum, intensity and size effect ... In the electric field and layer-to-layer interaction energy, the law of split-level of high-level Stark effect of spherical nanometer system is explored as well as the frequency of spectrum, intensity and size effect of coefficient of spontaneous radiation. Taking three layers CdS/HgS spherical nanometer system as an example, the influence of the electric field and layer-to- layer interaction energy is explored on Stark effect and spectrum. The results show that in the Stark effect system, the energy level is split based on 1, 3, ..., (2n-1), when it is in the electric field only, similar to the hydrogen atoms; and in the electric field and layer-to-layer interaction, it is split based on 1, 4, ~ -., n2; with the quantum transition, the frequency of the spectrum decreases with the increasing size of the system; apart from a few spectral lines, the intensity of most spectral lines will decreased as the size increases; while the coefficient of spontaneous radiation will increase with the increasing size; the electric field will cause the changes of spectrum frequency; its spectrum frequency shift is proportional to the square of the electric field intensity; apart from a few spectral lines, the frequency shift of spectral lines that is caused by the electric field and layer-to-layer interaction will decrease as the size increases; the interaction will make the level of electronic energy level lower slightly (the order of magnitude is between 10-7-10-9 eV), the slightly increased spectrum intensity and the slightly increased value of coefficient of spontaneous radiation, but it will not influence the frequency of spectrum, intensity, and the trend that coefficient of spontaneous radiation changes with the size; when the size is smaller, the layer-to-layer interaction effect will be significant. 展开更多
关键词 Layer-to-layer interaction energy CdS/HgS/CdS spherical nanometer system Stark effect Frequency shift of spectral line Coefficient of spontaneous radiation
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ANALYSIS FOR AIRCRAFT TAXIING AT VARIABLE VELOCITY ON UNEVENNESS RUNWAY BY THE POWER SPECTRAL DENSITY METHOD 被引量:2
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作者 聂宏 W.Kortuüm 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2000年第1期64-70,共7页
In this paper a novel approach for the analysis of non stationary response of aircraft landing gear taxiing over an unevenness runway at variable velocity is explored, which is based on the power spectral density met... In this paper a novel approach for the analysis of non stationary response of aircraft landing gear taxiing over an unevenness runway at variable velocity is explored, which is based on the power spectral density method. A concerned analytical landing gear model for simulating actual aircraft taxiing is formulated. The equivalent linearization results obtained by probabilistic method are inducted to treat landing gear non linear parameters such as shock absorber air spring force, hydraulic damping and Coulomb friction, tire stiffness and damping. The power spectral density for non stationary analysis is obtained via variable substitution and then Fourier transform. A representative response quantity, the overload of the aircraft gravity center, is analyzed. The frequency response function of the gravity overload is derived. The case study demonstrates that under the same reached velocity the root mean square of the gravity acceleration response from constant acceleration taxiing is smaller than that from constant velocity taxiing and the root mean square of the gravity acceleration response from lower acceleration taxiing is greater than that from higher acceleration. 展开更多
关键词 aircraft landing gear random vibration non stationary response power spectral density equivalent linearization
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Stress verification of a TLP under extreme wave environment
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作者 闫发锁 张大刚 +1 位作者 孙丽萍 戴仰山 《Journal of Marine Science and Application》 2009年第2期132-136,共5页
Stress response of a tension leg platform (TLP) in extreme environments was investigated in this paper. A location on one of the gussets was selected as the object point, where directional stresses were numerically ... Stress response of a tension leg platform (TLP) in extreme environments was investigated in this paper. A location on one of the gussets was selected as the object point, where directional stresses were numerically simulated and also experimentally verified by a strain gage. Environmental loading and the platform's structural strength were analyzed in accordance with industrial standards, utilizing linear wave theory and the finite element method (FEM). The fast Fourier transform technique was used to calculate the stress response amplitude operators (RAO) from the records of measurements. A comparison was performed between the stress RAO of the numerical simulation and that of the actual measurements. The results indicated that the stress RAO of the numerical simulation fitted well with measured data at specified wave headings with different periods. 展开更多
关键词 TLP stress RAO extreme environment numerical simulation monitoring measurement
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Growth of 0.55eV-GaInAsSb Quaternary Alloy Films for a Thermophotovoltaic Device by Liquid Phase Epitaxy
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作者 刘磊 陈诺夫 +2 位作者 杨晓丽 汪宇 高福宝 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第7期1258-1262,共5页
Lattice matched Ga1-x Inx Asy Sb1-y quaternary alloy films for thermophotovoltaic cells were successfully grown on n-type GaSb substrates by liquid phase epitaxy. Mirror-like surfaces for the epitaxial layers were ach... Lattice matched Ga1-x Inx Asy Sb1-y quaternary alloy films for thermophotovoltaic cells were successfully grown on n-type GaSb substrates by liquid phase epitaxy. Mirror-like surfaces for the epitaxial layers were achieved and evaluated by atomic force microscopy. The composition of the Ga1-x Inx Asy Sb1-y layer was characterized by energy dispersive X-ray analysis with the result that x- 0.2, y = 0.17. The absorption edges of the Ga1-x InxAsy Sb1-y films were determined to be 2. 256μm at room temperature by Fourier transform infrared transmission spectrum analysis, corresponding to an energy gap of 0.55eV. Hall measurements show that the highest obtained electron mobility in the undoped p-type samples is 512cm^2/(V · s) and the carrier density is 6.1 × 10^16 cm^-3 at room temperature. Finally,GaInAsSb based thermophotovol- taic cells in different structures with quantum efficiency values of around 60% were fabricated and the spectrum response characteristics of the cells are discussed. 展开更多
关键词 GAINASSB LPE THERMOPHOTOVOLTAIC spectrum response
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PIEZOSPECTROSCOPIC STUDY OF RESIDUAL STRESSES AROUND INDENTATIONS IN SiC/Al_O_3 NANOCOMPOSITE
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作者 陶杰 崔益华 杨斌鹏 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2003年第1期85-90,共6页
A new experimental measurement of residual stresses around Vickers′ indentations on the surface of the SiC/Al 2O 3 nanocomposites is proposed with the aid of a Raman microprobe. Results s how that the shifts of R... A new experimental measurement of residual stresses around Vickers′ indentations on the surface of the SiC/Al 2O 3 nanocomposites is proposed with the aid of a Raman microprobe. Results s how that the shifts of R lines in the fluorescence spectra va ry with the distance from the centre of indentation. The magnitude of load appli ed on the surface of the materials through the indenter influences the shifts of R lines to great extent. The luminescence of R lines of the materials before indenting is used to determine the residual stresses around the indentation in the materials, assuming that the stress tensor is transversely isotropic. Final ly, the term of hydrostatic stress is adopted to explain and compare different residual stresses around indentations with the increase of the indenting load an d the distance from the centre of indentations. < 展开更多
关键词 residual stress NANOCOMPOSITE piezospec troscopi c method INDENTATION SiC/Al 2O 3
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Quantum Effects on Global Structure of Liquid Water
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作者 林珂 胡乃银 +2 位作者 周晓国 刘世林 罗毅 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2013年第2期127-132,I0003,共7页
The structure difference between light and heavy liquid water has been systematically in- vestigated by high precision Raman spectroscopy over the temperature range of 5-85℃. Distinct difference between the Raman spe... The structure difference between light and heavy liquid water has been systematically in- vestigated by high precision Raman spectroscopy over the temperature range of 5-85℃. Distinct difference between the Raman spectral profiles of two different liquid waters is clearly observed. By analyzing the temperature-dependent Raman spectral contour using global fitting procedure, it is found that the micro-structure of heavy water is more ordered than that of light water at the same temperature, and the structure difference between the light and heavy water decreases with the increase of the temperature. The temperature off- set, an indicator for the structure difference, is determined to vary from 28 ℃ to 18 ℃ for the low-to-high temperature. It indicates that quantum effect is significantly not only at low temperature, but also at room temperature. The interaction energy among water molecules has also been estimated from van't Hoff's relationship. The detailed structural information should help to develop reliable force fields for molecular modeling of liquid water. 展开更多
关键词 Light and heavy water Quantum effect Raman spectra STRUCTURE Temperature offset
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RTD’s Relaxation Oscillation Characteristics with Applied Pressure 被引量:1
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作者 仝召民 薛晨阳 +2 位作者 张斌珍 刘俊 乔慧 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第1期39-44,共6页
The relaxation oscillation characteristics of a resonant tunneling diode (RTD) with applied pressure are reported. The oscillation circuit is simulated and designed by Pspice 8. 0, and the measured oscillation frequ... The relaxation oscillation characteristics of a resonant tunneling diode (RTD) with applied pressure are reported. The oscillation circuit is simulated and designed by Pspice 8. 0, and the measured oscillation frequency is up to 200kHz. Using molecular beam epitaxy (MBE) ,AIAs/lnx Ga1-x As/GaAs double barrier resonant tunneling structures (DBRTS) are grown on (100) semi-insulated (SI) GaAs substrate,and the RTD is processed by Au/Ge/Ni/Au metallization and an airbridge structure. Because of the piezoresistive effect of RTD,with Raman spectrum to measure the applied pressure, the relaxation oscillation characteristics have been studied, which show that the relaxation oscillation frequency has approxi- mately a - 17.9kHz/MPa change. 展开更多
关键词 resonant tunneling diode relaxation oscillation Raman spectrum piezoresistive effect
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The analysis of frequency-dependent characteristics for fluid detection: a physical model experiment 被引量:2
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作者 陈双全 李向阳 王尚旭 《Applied Geophysics》 SCIE CSCD 2012年第2期195-206,235,236,共14页
According to the Chapman multi-scale rock physical model, the seismic response characteristics vary for different fluid-saturated reservoirs. For class I AVO reservoirs and gas-saturation, the seismic response is a hi... According to the Chapman multi-scale rock physical model, the seismic response characteristics vary for different fluid-saturated reservoirs. For class I AVO reservoirs and gas-saturation, the seismic response is a high-frequency bright spot as the amplitude energy shifts. However, it is a low-frequency shadow for the Class III AVO reservoirs saturated with hydrocarbons. In this paper, we verified the high-frequency bright spot results of Chapman for the Class I AVO response using the frequency-dependent analysis of a physical model dataset. The physical model is designed as inter-bedded thin sand and shale based on real field geology parameters. We observed two datasets using fixed offset and 2D geometry with different fluid- saturated conditions. Spectral and time-frequency analyses methods are applied to the seismic datasets to describe the response characteristics for gas-, water-, and oil-saturation. The results of physical model dataset processing and analysis indicate that reflection wave tuning and fluid-related dispersion are the main seismic response characteristic mechanisms. Additionally, the gas saturation model can be distinguished from water and oil saturation for Class I AVO utilizing the frequency-dependent abnormal characteristic. The frequency-dependent characteristic analysis of the physical model dataset verified the different spectral response characteristics corresponding to the different fluid-saturated models. Therefore, by careful analysis of real field seismic data, we can obtain the abnormal spectral characteristics induced by the fluid variation and implement fluid detection using seismic data directly. 展开更多
关键词 Frequency-dependent characteristic fluid detection time-frequency analysis attenuation and dispersion physical model
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A Molecular Approach to Identification of the Chinese Drug“pu Gong Ying”(Herba Taraxaci)and Six Adulterants byDNA Fingerprinting Using Random Primed PolymeraseChain Resaction(PCR) 被引量:3
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作者 曹晖 毕培曦 邵鹏柱 《Journal of Chinese Pharmaceutical Sciences》 CAS 1996年第4期186-194,共9页
DNA fingerprinting among members of the Chinese drug Pu Gong Ying(Taraxacum mongolicum Hand,-Mazz.)and six adulterants of Tu Gong Ying were demonstrated with random-primed polymerase chain reaction(PCR)including arbit... DNA fingerprinting among members of the Chinese drug Pu Gong Ying(Taraxacum mongolicum Hand,-Mazz.)and six adulterants of Tu Gong Ying were demonstrated with random-primed polymerase chain reaction(PCR)including arbitrarily primed polymerase chain reaction(AP-PCR)and random amplified polymorphic DNA(RAPD).Distinctive,reproducible genomic fingerprints from DNA from 7 species belonged to Compositae were generated with two long(20 and 24 mer)and one short(10 mer)randomly chosen primers.The Pu Gong Ying can be differentiated from six species of Tu Gong Ying according to the banding pattems of their amplified DNA on agarose gels.The results showed that AP-PCR and RAPD methods can be used for identifying Chinese drugs.Moreover,the Similarity Indexes of the genomic DNA fingerprints showed that Pu Gong Ying and its adulterants are unrelated.Therefore,AP-PCR and RAPD methods can be used for identifying Chinese drugs. 展开更多
关键词 Chinese drug identification Taraxacum mongolicum DNA fingerprinting Polymerase chain reaction
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Analysis of the Antimicrobial Activity of Antimicrobial Peptides Extracted from Immunized Tenebrio molitor Induced by Different Microbial Treatments Against 26 Pathogens 被引量:3
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作者 谢咸升 董建臻 +4 位作者 李静 李永利 王圆圆 李小凤 张亚南 《Agricultural Science & Technology》 CAS 2010年第9期1-4,9,共5页
[Objective] The study was to explore whether antimicrobial activity of the antimicrobial peptides extracted from immunized Tenebrio molitor varied with different pathogens as inducers.[Method]By inducing T.molitor hun... [Objective] The study was to explore whether antimicrobial activity of the antimicrobial peptides extracted from immunized Tenebrio molitor varied with different pathogens as inducers.[Method]By inducing T.molitor hungry larvaes to generate immune response via feeding with bacteria and with fungi or actinomycete post to pricking,the antimicrobial peptides extracts were obtained by grinding and centrifuging the cultures.Its antimicrobial activity against 26 pathogens was measured by bacteriostatic ring,and evaluated by trisection to four types and inhibitory spectrum.[Result]Both the antimicrobial activity and antimicrobial spectrum of the antimicrobial peptides extracts varied remarkably among different pathogens as inducers.[Conclusion]Bio-control used strains have obvious advantage in inducing the insect to express body fluid immunity material-antimicrobial peptides. 展开更多
关键词 Tenebrio molitor Induced immune response Antimicrobial peptides Antimicrobial activity Antimicrobial spectrum
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Evaluation on residual stresses of silicon-doped CVD diamond films using X-ray diffraction and Raman spectroscopy 被引量:10
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作者 陈苏琳 沈彬 +2 位作者 张建国 王亮 孙方宏 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第12期3021-3026,共6页
The effect of silicon doping on the residual stress of CVD diamond films is examined using both X-ray diffraction (XRD) analysis and Raman spectroscopy measurements. The examined Si-doped diamond films are deposited o... The effect of silicon doping on the residual stress of CVD diamond films is examined using both X-ray diffraction (XRD) analysis and Raman spectroscopy measurements. The examined Si-doped diamond films are deposited on WC-Co substrates in a home-made bias-enhanced HFCVD apparatus. Ethyl silicate (Si(OC2H5)4) is dissolved in acetone to obtain various Si/C mole ratio ranging from 0.1% to 1.4% in the reaction gas. Characterizations with SEM and XRD indicate increasing silicon concentration may result in grain size decreasing and diamond [110] texture becoming dominant. The residual stress values of as-deposited Si-doped diamond films are evaluated by both sin2ψ method, which measures the (220) diamond Bragg diffraction peaks using XRD, with ψ-values ranging from 0° to 45°, and Raman spectroscopy, which detects the diamond Raman peak shift from the natural diamond line at 1332 cm-1. The residual stress evolution on the silicon doping level estimated from the above two methods presents rather good agreements, exhibiting that all deposited Si-doped diamond films present compressive stress and the sample with Si/C mole ratio of 0.1% possesses the largest residual stress of ~1.75 GPa (Raman) or ~2.3 GPa (XRD). As the silicon doping level is up further, the residual stress reduces to a relative stable value around 1.3 GPa. 展开更多
关键词 silicon-doped diamond films silicon doping residual stress X-ray diffraction Raman spectroscopy
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A Smog Chamber Facility for Qualitative and Quantitative Study on Atmospheric Chemistry and Secondary Organic Aerosol 被引量:5
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作者 胡长进 程跃 +9 位作者 潘刚 盖艳波 顾学军 赵卫雄 王振亚 张为俊 陈军 刘付轶 单晓斌 盛六四 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2014年第6期631-639,I0003,共10页
In order to investigate the atmospheric oxidation processes and the formation of secondary organic aerosol (SOA), an indoor environmental reaction smog chamber are constructed and characterized. The system consists ... In order to investigate the atmospheric oxidation processes and the formation of secondary organic aerosol (SOA), an indoor environmental reaction smog chamber are constructed and characterized. The system consists of the collapsible ~830 L FEP Teflon film main reactor, in which the atmospheric chemical reactions take place and the formation of SOA occurs under the simulated atmospheric conditions, and the diverse on-line gas- and particle-phase instrumentation, such as the proton transfer reaction mass spectrometer, the synchrotron radiation photoionization mass spectrometer, the aerosol laser time-of-flight mass spectrometer, and other traditional commercial instruments. The initial characterization experiments are described, concerning the temperature and ultraviolet light intensity, the reactivity of the pure air, the wall loss rates of gaseous compounds and particulate matter. And the initial evaluation experiments for SOA yields from the ozonolysis of α-pinene and for mass spectra of the products resulting from the photooxidation of OH initiated isoprene are also presented, which indicate the applicability of this facility on the studies of gas-phase chemical mechanisms as well as the formation of SOA expected in the atmosphere. 展开更多
关键词 Smog chamber Atmospheric chemical reactions Secondary organic aerosol Mass spectrum
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A Straightforward Method of Calculating Finely the Soft X-Ray Spectra of Hydrogenlike Highly Ionized-States
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作者 尹钊 张国营 张学龙 《Journal of Southeast University(English Edition)》 EI CAS 2001年第2期87-90,共4页
A new method of calculating finely the soft X ray spectra of hydrogenlike highly ionized states is presented. It is based on the relation of the ionicity and the ionization energies of hydrogenlike atoms and the new... A new method of calculating finely the soft X ray spectra of hydrogenlike highly ionized states is presented. It is based on the relation of the ionicity and the ionization energies of hydrogenlike atoms and the new model of potential function of hydrogenlike atoms. The relativistic revision and the spin orbit couping of excitation energy levels are taken into account. The calculated results are in good agreement with the experiments. 展开更多
关键词 hydrogenlike ions spectra of soft X ray effect of ionicity relativistic effect
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Interface Reaction of SiO_2/Ta and Its Influence on Cu Diffusion 被引量:1
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作者 龙世兵 马纪东 +4 位作者 于广华 赵洪辰 朱逢吾 张国海 夏洋 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2002年第10期1046-1050,共5页
Ta/NiFe film is deposited on Si substrate precoated with SiO_2 by magnetron sputtering.SiO_2/Ta interface and Ta_5Si_3 standard sample are investigated by using X-ray photoelectron spectroscopy (XPS) and peak decompos... Ta/NiFe film is deposited on Si substrate precoated with SiO_2 by magnetron sputtering.SiO_2/Ta interface and Ta_5Si_3 standard sample are investigated by using X-ray photoelectron spectroscopy (XPS) and peak decomposition technique.The results show that there is a thermodynamically favorable reaction at the SiO_2/Ta interface:37Ta+15SiO_2=5Ta_5Si_3+6Ta_2O_5.The more stable products Ta_5Si_3 and Ta_2O_5 may be beneficial to stop the diffusion of Cu into SiO_2. 展开更多
关键词 copper interconnection in ULSI diffusion barrier interface reaction X-ray photoelectron spectroscopy
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EIS studies the effect of Zinc to Al-Zn alloy used for cathodic protection in 3% NaCl solution 被引量:1
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作者 郝小军 雷英春 +2 位作者 侯华 赵宇宏 王一都 《Journal of Measurement Science and Instrumentation》 CAS CSCD 2017年第2期110-118,共9页
Electrochemical impendence spectroscopy (EIS) is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the ac... Electrochemical impendence spectroscopy (EIS) is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the activation mechanism of zinc in Al-Zn alloys is achieved. There are three intermediates in the dissolution process: Znad^+, Znad^2+ and Alad^+, ,of which only Zni can activate Al-Zn alloys. Most Znnd^+ is produced by β-phase,and the alloys with 2. 3% - 3. 8% (wt) Zn dissolve rapidly. The Al-Zn alloys of heart-shaped EIS are active in 3% NaCl solution, thus EIS characteristic can be used to distinguish the activa-tion of Al-Zn alloys. 展开更多
关键词 Al-Zn alloy sacrificial anode reaction model electrochemical impendence spectroscopy (EIS activation mecha-nism zinc enrichment phase (β-phase)
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Vertical-to-horizontal response spectral ratio for offshore ground motions:Analysis and simplified design equation 被引量:12
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作者 陈宝魁 王东升 +2 位作者 李宏男 孙治国 李超 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第1期203-216,共14页
In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(... In order to study the differences in vertical component between onshore and offshore motions,the vertical-to-horizontal peak ground acceleration ratio(V/H PGA ratio) and vertical-to-horizontal response spectral ratio(V/H) were investigated using the ground motion recordings from the K-NET network and the seafloor earthquake measuring system(SEMS).The results indicate that the vertical component of offshore motions is lower than that of onshore motions.The V/H PGA ratio of acceleration time histories at offshore stations is about 50%of the ratio at onshore stations.The V/H for offshore ground motions is lower than that for onshore motions,especially for periods less than 0.8 s.Furthermore,based on the results in statistical analysis for offshore recordings in the K-NET,the simplified V/H design equations for offshore motions in minor and moderate earthquakes are proposed for seismic analysis of offshore structures. 展开更多
关键词 offshore ground motion vertical component simplified design equation vertical-to-horizontal response spectral ratio (V/H) vertical-to-horizontal peak ground acceleration ratio (V/H PGA ratio) K-NET network seafloor earthquake measuring system (SEMS)
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Analysis of the Effects of Slope Geometry on the Dynamic Response of a Near-field Mountain from the Wenchuan Earthquake 被引量:7
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作者 XIAO Shiguo FENG Wenkai ZHANG Jianjing 《Journal of Mountain Science》 SCIE CSCD 2010年第4期353-360,共8页
Fourier spectra and acceleration response spectra of near-field acceleration records of the 2008 Wenchuan Earthquake have been calculated.Relative fundamental frequencies(or predominant periods) were characterized.The... Fourier spectra and acceleration response spectra of near-field acceleration records of the 2008 Wenchuan Earthquake have been calculated.Relative fundamental frequencies(or predominant periods) were characterized.Then,the natural frequencies of a range of slopes with different geometric characteristics,such as height,slope ratio,and pattern,were analyzed.The seismic responses of the slopes were compared,and the variability of seismic response with the above geometric elements was found.Results show that if slope height increases,and provided that other conditions are unchanged,the natural frequency of the first mode of a doublesurface slope will change as a power law.However,natural frequencies will diminish(based on a parabolic function) as the slope angle becomes large.Both the surface pattern and the number of surfaces on a slope can have a great impact on the seismic response of the slope.Moreover,within a certain range of slope heights or angles,either height or angle will also greatly influence the variability of the seismic response.The results of this research will be helpful to understanding seismic dynamic response features and explaining the ways that slope stability can be affected by earthquakes. 展开更多
关键词 Wenchuan Earthquake SLOPE Geometric features Dynamic response Naturalfrequency
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