检索结果-南通市图书馆

Preparation and characterization of hexadecane microcapsule with polyurea-melamine formaldehyde resin shell materials

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2010年第5期21卷 533-537页

作者： Gao, Gui Bo qian, chun Xiang Gao, Min Jie Southeast Univ Sch Mat Sci & Engn Nanjing 211189 Peoples R China

This paper gives a brief report of the preparation of hexadecane microcapsule with polyurea-melamine formaldehyde resin shell materials(HMPM).The sealing performance and thermal stability of HMPM was enhanced much more effectively than that of microcapsule with polyurea shell material(HPM).The results of microscopical imaging analysis system,DSC,TG,and laser particle analyzer were briefly introduced.

关键词： Hexadecane Polyurea Melamine formaldehyde resin Microcapsule Phase change properties

Effect of Maturity Stage on the Gene Expression of Antioxidative Enzymes in Cucumber (Cucumis sativus L.) Fruits Under Chilling Stress

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2013年第8期12卷 1495-1500页

作者： qian chun-lu MI Hong-bo ZHAO Yu-ying HE Zhi-ping MAO Lin-chun College of Biosystem Engineering and Food Science Zhejiang University College of Horticulture and Gardening Yangtze University School of Agriculture and Food Science Zhejiang A&F University

The gene expression pattems of antioxidative enzymes in cucumber （Cucumis sativus L.） fruits at four different maturity stages, immature （3-8 d after anthesis （DAA）, mature （9-16 DAA）, breaker （17-22 DAA）, and yellow （35-40 DAA）, were determined before and after cold storage at 2℃ for 9 d and after subsequent rewarming at 20℃ for 2 d. The electrolyte leakage and malondialdehyde content in cucumber fruits were increased after cold storage and subsequent rewarming. Increased expressions of peroxidase, ascorbate peroxidase （APX）, and monodehydroascorbate reductase after cold storage played an important role in cucumber fruits to cope with chilling injury. The elevated cyt-superoxide dismutase, catalase, APX and dehydroascorbate reductase after subsequent rewarming in cucumber fruits facilitated the recovery from chilling stress. The highest expression levels of all the seven antioxidative enzyme genes in yellow fruits might be responsible for the enhanced chilling tolerance. Cucumber fruits at earlier developmental stages was more susceptible to chilling stress than those at later stages. The relative higher gene expressions of antioxidative enzymes genes at earlier developmental stages may be the responses to the sever oxidative stress caused by chilling injury.

关键词： cucumber fruit maturity postharvest chilling injury antioxidative enzyme

Spot and Facula Activity Variations of the Eccentric Detached Eclipsing Binary KIC 8098300 Based on the Time-series Orbital Solutions

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第1期22卷 174-188页

作者： Hu-Biao Niu Jian-Ning Fu Jia-Xin Wang chun-qian Li Department of Astronomy Beijing Normal UniversityBeijing 100875China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

The LAMOST spectra and Kepler light curves are combined to investigate the detached eclipsing binary KIC 8098300,which shows the O’Connell effect caused by spot/facula *** radial velocity(RV)measurements are derived by using the tomographic spectra disentangling *** mass ratio q=K1/K2=0.812±0.007,and the orbital semimajor axis a sin i=14.984±0.048 R_(⊙)are obtained by fitting the RV *** optimize the binary model concerning the spot/facula activity with the code PHOEBE and obtain precise parameters of the orbit including the eccentricity e=0.0217±0.0008,the inclination i=87°.71±0°.04,and the angle of periastronω=284°.1±0°.*** masses and radii of the primary and secondary star are determined as M_(1)=1.3467±0.0001 M_(⊙),R_(1)=1.569±0.003 R_(⊙),and M_(2)=1.0940±0.0001 M_(⊙),R_(2)=1.078±0.002 R_(⊙),*** ratio of temperatures of the two component stars is r_(teff)=0.924±*** also obtain the periastron precession speed of 0.000024±0.000001 day *** residuals of out-of-eclipse are analyzed using the auto-correlation function and the discrete Fourier *** spot/facula activity is relatively weaker,but the lifetime is longer than that of most single main sequence stars in the same temperature *** average rotation period of the spots P_(rot)=4.32 days is slightly longer than the orbital period,which may be caused by either the migration of spots/faculae along the longitude or the latitudinal differential *** activity may be spot-dominated for the secondary star and facula-dominated for the primary *** method of this work can be used to analyze more eclipsing binaries with the O’Connell effect in the Kepler field to obtain the precise parameters and investigate the difference of spot behavior between binaries and single *** is helpful for a deeper understanding of the stellar magnetic activity and dynamo theory.

关键词： (stars:)binaries:eclipsing (stars:)starspots stars:individual(KIC 8098300)

Relationship between Hydrogen Diffusion and Blistering Nucleation and Growth

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2016年第11期23卷 1188-1194页

作者： Jin-xu LI Hang YIN Xi-na YANG qian LI Ping ZHANG chun-qian XIE Yan-jing SU Li-jie QIAO Corrosion and Protection Center Environment Sensitive Fracture Laboratory(MOE)University of Science and Technology Beijing

The formation condition of hydrogen blister in 18Ni maraging steel without any inner or external stress was investigated. The results show that the critical diffusible hydrogen concentration of a blister forming is about 1.4×10^-5 , which is corresponding to the current density of 30 mA/cm^2 during cathodic charging in a sodium hydroxide solution. For a 0.1 cm thick sample, no matter the current density is equal to or much larger than the critical value, it spends at least about 132 h to form a hydrogen blister when hydrogen charging in single direction. It is approxi- mately equal to the time for hydrogen atom to diffuse throughout the sample, which exactly depends on the hydrogen diffusion coefficient and the penetration depth. The very first clear suggestion was reported that the incubation period for hydrogen blister nucleation was necessary. According to the Fick＇s laws, calculations show that the normalized hydrogen concentration in the escaping surface almost reaches 0.96 times of the charging surface, which means that the diffusion almost reaches a dynamic balance. A model was illustrated to describe the competitive relationship between hydrogen diffusion and blister formation.

关键词： hydrogen blister trap maraging steel hydrogen diffusion incubation time

Optically Modulated Bistability in Quantum Dot Resonant Tunneling Diodes

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2013年第4期30卷 221-224页

作者： WENG qian-chun AN Zheng-Hua HOU Ying ZHU Zi-qiang Key Laboratory of Polar Materials and Devices(Ministry of Education East China Normal UniversityShanghai 200241 Institute of Advanced Materials and State Key Laboratory of Surface Physics Fudan UniversityShanghai 200433 Shanghai Advanced Research Institute Chinese Academy of SciencesShanghai 201210

InAs quantum dots are introduced into resonant tunneling diodes to study the electronic transport behavior,and a wide bistability(ΔV~0.8 V)is observed in the negative differential resistance *** on an analytic model,we attribute the observed distinct bistability of a resonant tunneling diodes with quantum dots to the feedback dependence of energy of the electron-storing quantum dots on the tunneling current ***,we find that this wide bistable region can be modulated sensitively by light illumination and becomes narrower with increasing light *** results suggest that the present devices can be potentially used as sensitive photodetectors in optoelectronic fields.

关键词： tunneling quantum resonant

Porous boronate affinity monolith for on-line extraction coupled to high-performance liquid chromatography for sensitive analysis of heterocyclic aromatic amines in food samples

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2015年第12期26卷 1470-1477页

作者： qian-chun Zhang Ying-Yi Cheng Gong-Ke Li Xiao-Hua Xiao School of Chemistry and Chemical Engineering Sun Yat-sen University School of Biology and Chemistry Xingyi Normal University for Nationalities

A novel on-line solid-phase microextraction–high-performance liquid chromatography（SPME–HPLC）system was developed for the determination of heterocyclic aromatic amines（HAAs） in food samples. A poly（vinylphenylboronic acid-co-ethylene glycol dimethacrylate） polymer monolith was prepared for on-line efficient extraction and large-volume injection was used to increase the sensitivity of *** polymermonolith, based on a ternary porogen, was prepared by in situ polymerization of vinylphenylboronic acid（VPBA） and ethylene glycol dimethacrylate（EGDMA） in a fused-silica capillary column. It showed good permeability, high extraction capacity, and high selectivity. The column-tocolumn reproducibility was satisfactory, and the enrichment factors for HAAs were 3746–*** influencing the on-line extraction efficiency, including p H of sample solutions, flow rate of extraction and desorption, and desorption volume, were investigated. The proposed method had low limit of detection（0.10–0.15 ng/L） and good linearity. Trace HAAs in roast beef and lamb samples were determined, and the amounts of 2-amino-3-methylimidazo[4,5-f]quinoline, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, and 2-amino-3,4,7,8-tetramethyl-3H-imidazo[4,5-f]quinoxaline in these samples were 0.235–2.08 ng/g. The recoveries for the five HAAs ranged from74.3% to 119%, and the relative standard deviation（RSDs） were less than 8.2%. The results showed that the proposed on-line method was highly sensitive for monitoring HAAs in different food samples.

关键词： heterocyclic aromatic amines polymerization glycol tetramethyl selectivity desorption permeability silica

The Physical Properties and Starspot Activity of the Triple System KIC 6525196

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第7期22卷 214-223页

作者： Yang Pan Jian-Ning Fu Xiao-Bin Zhang Jia-Xin Wang chun-qian Li School of Physics and Astronomy China West Normal UniversityNanchong 637002China Department of Astronomy Beijing Normal UniversityBeijing 100875China Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100012China School of Science Chongqing University of Posts and TelecommunicationsChongqing 400065China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

We present the results of photometric and spectroscopic analyses for the triple-lined system KIC 6525196,an eclipsing binary accompanied by a third *** modeling the Kepler light curves and radial velocities from LAMOST and HIDES observations,absolute parameters of the system are *** components of the eclipsing binary are found to be solar-like stars with masses and radii of M= 1.0286 ± 0.0026 M,R= 1.127 ± 0.008 *** M=0.9667 ± 0.0024 M,R=0.963 ± 0.007 *** mass of the third star is determined to be M= 0.772 ± 0.010 *** the out-of-eclipse light residuals,we measure rotation period and decay timescale of an active region by using the autocorrelation *** comparison to the Sun,the activity level of the system is significantly *** addition,a possible short photometric activity cycle of~244 days is detected.

关键词： stars:activity (stars:)binaries:eclipsing (stars:)binaries:spectroscopic

Characterization and Expression Analysis of Four Glycine-Rich RNA-Binding Proteins Involved in Osmotic Response in Tobacco (Nicotiana tabacum cv. Xanthi)

在线全文

学校读者我要写书评

暂无评论

Agricultural Sciences in China 2010年第11期9卷 1577-1587页

作者： CHEN Xuan ZENG qian-chun LU Xiu-ping YU Di-qiu LI Wen-zheng Industrial Crop Research Institute Yunnan Academy of Agricultural Sciences Kunming 650205 P.R. China College of Agronomy and Biotechnology Yunnan Agricultural University Kunming 650201 P.R. China Yunnan Tobacco Research Institute Yuxi 653100 P.R.China Xishuangbanna Tropical Botanic Garden Chinese Academy of Sciences Kunming 650223 P.R. China

Plants have developed many signals and specific genes＇ regulations at both transcriptional and post-transcriptional levels in order to tolerate and adapt to various environmental stresses. RNA-binding proteins （RBPs） play crucial roles in the post- transcriptional regulation via mRNA splicing, polyadenylation, sequence editing, transport, mRNA stability, mRNA localization, and translation. In this paper, four cDNAs of glycine-rich RNA-binding proteins （GR-RBPs）, named NtRGP-la, -lb, -2, and -3, were isolated from Nicotiana tabacum by RT-PCR analysis, and special emphases were given to the sequences alignment, phylogenetic analysis and gene expression. Sequences alignment revealed minor difference of cDNA sequences, but no difference of deduced proteins between N. sylvestris and N. tabacum. Phylogenetic alignment revealed that four cDNAs in tobacco were clustered into two different groups. NtRGP-2 and -3 were evolutionarily closest to Arabidopsis GR-RBPs genes and related to animal GR-RBPs genes, while NtRGP-la and -lb were closest to Gramineae GR-RBPs genes. The expression analyses of these four NtRGPs in response to different abiotic stresses revealed the similar expression pattern. Moreover, the four NtRGPs, especially NtRGP-la and NtRGP-3, were strongly induced by stresses including water, wound, cold, and high temperature, weakly induced by PEG, drought and SA, while reduced by NaC1 and unaffected by ABA treatment. The fact that all of these abiotic stresses included in our experiments affected the water balance and resulted in osmotic stress on cellular level, suggests that NtRGPs in tobacco should be a family of crucial osmosis-related proteins, and may play a key role in signal transduction with ABA-independent pathway under abiotic stresses.

关键词： glycine-rich RNA-binding proteins abiotic stresses phylogenesis expression pattern osmotic stress

Exploring the spectral information content in the LAMOST medium-resolution survey(MRS)

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2020年第4期20卷 57-68页

作者： Bo Zhang Chao Liu chun-qian Li Li-Cai Deng Tai-Sheng Yan Jian-Rong Shi Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Although high-resolution stellar spectra allow us to derive precise stellar labels(effective temperature,metallicity,surface gravity,elemental abundances,etc.)based on resolved atomic lines and molecular bands,low-resolution spectra have been proved to be competitive in determining many stellar labels at comparable *** is useful to consider the spectral information content when assessing the capability of a stellar spectrum in deriving precise stellar *** this work,we quantify the information content brought by the LAMOST-II medium-resolution spectroscopic survey(MRS)using the gradient spectra as well as the coefficients-of-dependence(CODs).In general,the wavelength coverage of the MRS well constrains the stellar labels but the sensitivities of different stellar labels vary with spectral types and metallicity of the stars of ***,this affects the performance of the stellar label determination from the MRS *** applying the SLAM method to the synthetic spectra which mimic the MRS data,we find that the precision of the fundamental stellar parameters Teff,log g and[M/H]are better when combining both the blue and red bands of the *** is especially important for warm stars because the Hαline located in the red part plays a more important role in determining the effective temperature for warm *** blue and red parts together,we are able to reach similar performance to the low-resolution spectra except for warm ***,at[M/H]-2.0 dex,the uncertainties of fundamental stellar labels estimated from MRS are substantially larger than that from low-resolution *** also tested the uncertainties of Teff,log g and[M/H]from MRS data induced from the radial velocity mismatch and find that a mismatch of about 1 km s-1,which is typical for LAMOST MRS data,would not significantly affect the stellar label ***,reference precision limits are calculated using synthetic gradient spectra,according to which we expect a

关键词： methods:data analysis methods:statistical stars:fundamental parameters stars:abundances