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HETEROAROMATIC POLYMERS—HIGH TEMPERATURE POLYPYRROLONES DERIVED FROM 2,6-BIS(3',4'-DIAMINOPHENYL)-4-BIPHENYLPYRIDINE AND VARIOUS AROMATIC DIANHYDRIDES

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Chinese Journal of Polymer Science 2005年第5期23卷 521-529页

作者： Hai-xia Yang jin-gang liu Xiao-juan Zhao Yan-feng Li Lin Fan Shi-yong Yang School of Chemistry and Chemical Engineering Lanzhou University Lanzhou 730000 China Laboratory of Advanced Polymer Materials Institute of Chemistry Chinese Academy of Sciences Beijing 100080 China

A new type of aromatic tetraarnine containing biphenyl moiety in the side chain was synthesized via a modified Chichibabin＇s reaction. 3-Nitro-4-acetamidoacetophenone was reacted with 4-phenyl benzaldehyde in the presence of ammonium acetate to obtain 2,6-bis（3＇,4＇-diaminophenyl）-4-biphenyl pyridine （DPPA）. A series of polypyrrolones （PPys） were prepared using tetraamine and various aromatic dianhydrides via a two-step cyclization procedure. All the PPys show excellent high temperature stabilities with the initial decomposition temperatures of 530-549℃ and residual weight ratio of 49%-80% at 750℃ in nitrogen. The polymers exhibit no apparent glass transition temperatures （Tgs） except PPy-1 （Tg= 327℃）, which is derived from tetraamine DPPA and 2,2-bis[4-（3＇,4＇-dicarboxyphenoxy）-phenyl]propane dianhydride （BPADA）. In addition, the polymers have acceptable mechanical properties with the tensile strength of 65-94 MPa. The PPy films show excellent hydrolysis-resistance in alkaline aqueous medium and could maintain most of the properties even after boiling in 10% aqueous sodium hydroxide solution for a week.

关键词： Tetraamine Polypyrrolone Pyridine High temperature polymers Film Hydrolysis-resistance.

Assimilation of Chinese Fengyun-3B Microwave Temperature Sounder radiances into the Global GRAPES system with an improved cloud detection threshold

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Frontiers of Earth Science 2016年第1期10卷 145-158页

作者： juan LI Guiqing liu Numerical Weather Prediction Center China Meteorological Administration Beijing 100081 China National Meteorological Center China Meteorological Administration Beijing 100081 China

Fengyun-3B （FY-3B） is the second polar- orbiting satellite in the new Fengyun-three series. This paper describes the assimilation of the FY-3B Microwave Temperature Sounder （MWTS） radiances in the Chinese Numerical Weather prediction system - the Global and Regional Assimilation and PrEdiction System （GRAPES）. A quality control procedure for the assimilation of the FY- 3B MWTS radiance was proposed. Extensive monitoring before assimilation shows that the observations of channel 4 are notably contaminated. Channels 2 and 3 are used in this research. A cloud detection algorithm with an improved cloud-detection threshold is determined and incorporated into the impact experiments. The clear field- of-view （FOV） percentage increased from 42% to 57% with the new threshold. In addition, the newly added FOVs are located in the clear region, as demonstrated by the cloud liquid water path data from NOAA-18. The impact of the MWTS radiances on the prediction of GRAPES was researched. The observation biases ofFY-3B MWTS O-B （differences between satellite observations and model simulations） significantly decreased after an empirical bias correction procedure. After assimilation, the residual biases are small. The assimilation of the FY-3B MWTS radiances shows a positive impact in the Northern Hemisphere and a neutral impact in the Southern Hemisphere.

关键词： Fengyun-3B (FY-3B) MWTS quality control GRAPES

基于模糊层次综合分析的残损状态纯木结构安全评估方法

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土木与环境工程学报（中英文） 2025年第1期47卷 110-117页

作者：杨庆山赵剑波刘纲王娟重庆大学土木工程学院重庆400045 北京交通大学土木建筑工程学院北京100044

现存古建筑大多带伤服役,体内残损状态复杂多样,且对古建筑进行的加固维修与原有残损对结构本体的安全性能影响截然相反。为实现对古建筑的预防性保护,需要量化古建筑纯木结构中的残损状态及修缮措施对其安全状态的影响。基于山西万荣... 详细信息

现存古建筑大多带伤服役,体内残损状态复杂多样,且对古建筑进行的加固维修与原有残损对结构本体的安全性能影响截然相反。为实现对古建筑的预防性保护,需要量化古建筑纯木结构中的残损状态及修缮措施对其安全状态的影响。基于山西万荣飞云楼各构件残损状态普查统计数据,结合现有规范及工程经验对构件残损状态等级详细划分,建立4级模糊层次分析模型,确定结构体中承重构件及构件残损类型的权重值及判断矩阵,通过模糊层次分析方法对飞云楼进行安全状态评估。结果表明,建立的模糊层次安全评价模型能反映残损状态及修缮措施对飞云楼安全状态的影响,有效将结构评价与构件评价联系起来,验证了修缮措施能有效增强古建筑结构本体的安全性及稳定性,该模型及方法可以应用到多层古建木结构的安全等级评价中。

关键词：飞云楼纯木结构残损状态修缮加固模糊层次分析方法安全评估

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Spin-Orbit Components of Resonant Satellite Photoionization of Atomic Cu

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Chinese Physics Letters 1996年第12期13卷 899-901页

作者： liu jin-chao Institute of Physics Sichuan Union UniversityChengdu 610065 Department of Physics University of VirginiaCharlottesvilleVirginia 22901 U.S.A.

A new approach of the study on the spin-orbit components of resonant satellite photoionization has been carried out from many-body perturbation *** 3d^(8)4s^(2)(^(1)G,^(3)F,^(1)D)satellite lines of atomic Cu are resonantly enhanced and separated by the spin-orbit splitting at the energy of the 3p^(6)3d^(10)4s→3p^(5)(^(2)P_(1/2),^(2)P_(3/2))3d^(10)4s^(2) *** calculated results showing that the spin-orbit splitting leads to the separation of resonant peaks of satellite lines are in good agreement with experiment.

关键词： theory experiment resonant

Cholesterol metabolism and homeostasis in the brain

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Protein & Cell 2015年第4期6卷 254-264页

作者： juan Zhang Qiang liu Chinese Academy of Sciences Key Laboratory of Brain Function and Disease and School of Life Sciences University ofScience and Technoloqv of China. Hefei 230026. China

Cholesterol is an essential component for neuronal physiology not only during development stage but also in the adult life. Cholesterol metabolism in brain is in- dependent from that in peripheral tissues due to blood- brain barrier. The content of cholesterol in brain must be accurately maintained in order to keep brain function well. Defects in brain cholesterol metabolism has been shown to be implicated in neurodegenerative diseases, such as Alzheimer＇s disease （AD）, Huntington＇s disease （HD）, Parkinson＇s disease （PD）, and some cognitive deficits typical of the old age. The brain contains large amount of cholesterol, but the cholesterol metabolism and its complex homeostasis regulation are currently poorly understood. This review will seek to integrate current knowledge about the brain cholesterol metabo- lism with molecular mechanisms.

关键词： cholesterol metabolism homeostasis,apoE

Investigation of weak interlayer coupling in 2D layered GeS_(2) from theory to experiment

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Nano Research 2022年第2期15卷 1013-1019页

作者： Hui-juan Yan Zongbao Li Shun-Chang liu Xia Wang Xing Zhang Ding-Jiang Xue jin-Song Hu Beijing National Laboratory for Molecular Sciences(BNLMS) CAS Key Laboratory of Molecular Nanostructure and NanotechnologyInstitute of ChemistryChinese Academy of SciencesBeijing 100190China School of Material and Chemical Engineering Institute of Cultural and Technological Industry Innovation ofTongrenTongren UniversityTongren 554300China University of Chinese Academy of Sciences Beijing 100049China

Interlayer coupling as a unique feature for two-dimensional(2D)materials may influence their thickness-dependent physical properties,especially the bandgap due to quantum confinement ***-studied 2D materials usually possess strong interlayer coupling such as most of transition metal dichalcogenides(TMDs),PtS_(2) and so ***,2D materials with weak interlayer coupling are rarely referred that mainly focus on ReS_(2),as well as its counterpart ReSe_(2).Here we report a new member of weak interlayer coupling 2D materials,germanium disulfide(GeS_(2)).The interlayer interaction in GeS_(2) is investigated from theory to *** density functional theory calculations,we find that this extraordinarily weak interlayer coupling in GeS_(2) originates from the weak hybridization of interlayer S ***-dependent Raman spectra of GeS_(2) flakes exhibit that the Raman peaks remain unchanged when increasing the thickness;and a small first-order temperature coefficient of-0.00857 cm^(-1)·K^(-1) is obtained from the temperature-dependent Raman *** experimental results further confirm the weak interlayer coupling in GeS_(2).

关键词： interlayer coupling two-dimensional GeS_(2) temperature coefficient

Cytological Behavior of Hybridization Barriers Between Oryza sativa and Oryza officinalis

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Agricultural Sciences in China 2011年第10期10卷 1489-1500页

作者： FU Xue-lin LU Yong-gen liu Xiang-dong LI jin-quan ZHAO Xing-juan Key Laboratory of Plant Molecular Breeding Guangdong Province/College of Agriculture South China Agricultural University Guangzhou510642 P.R. China

Oryza officinalis is one of the important wild species in the tertiary gene pool of Oryza sativa. It has a number of elite genes for rice breeding in resistance or tolerance. However, breeding barriers are so serious that the gene transfer is much difficult by sexual cross method between O. sativa and O. officinalis. Characteristics of the breeding barriers were systemically studied in this paper. When both the diploid （AA, 2n=2x=24） and autotetraploid （AAAA, 2n=4x=48） cultivated rice were crossed as maternal parents with O. officinalis （CC, 2n=2x=24）, none F1 hybrid seeds were obtained. The young hybrid ovaries aborted at 13-16 d after pollinations （DAP）. By rescuing hybrid embryos, in vitro F1 plantlets were obtained in 2x×2x combinations with the crossabilities lower than 0.5%. Lower rates of double-fertilization and abnormal development of hybrid embryo and endosperm were mainly observed in both combinations of 2x×2x and 4x×2x. Free endosperm nuclei in hybrid degenerated early at 1 DAP in a large scale. Almost no normal endosperm cells formed at 3 DAP. Development of a lot of embryos ceased at globularor pear-shaped stage as well as some degenerated gradually. The hybrid plantlets were both male and female sterility. Due to the abnormal development, a diversity of abnormal embryo sacs formed in hybrids, and hybrid pollen grains were typically abortive. It showed that conflicts of genome A and C in hybrid induced abnormal meioses of meiocytes.

关键词： breeding barriers interspecific hybridization crossability hybrid sterility Oryza sativa Oryza officinalis

低温下玄武岩纤维混凝土劈拉强度尺寸效应试验

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哈尔滨工业大学学报 2025年第1期57卷 101-109页

作者：余文轩范美妤金浏杜修力清华大学土木水利学院北京100084 城市减灾与防灾防护教育部重点实验室(北京工业大学) 北京100124

为研究极端低温作用下结构尺寸和纤维体积分数对玄武岩纤维混凝土劈拉强度的定量影响规律和作用机制,设计了4种尺寸(边长分别为70、100、150和200 mm)、4种纤维体积分数(分数范围0%~0.5%)的玄武岩纤维混凝土立方体试块在常温和低温下(... 详细信息

为研究极端低温作用下结构尺寸和纤维体积分数对玄武岩纤维混凝土劈拉强度的定量影响规律和作用机制,设计了4种尺寸(边长分别为70、100、150和200 mm)、4种纤维体积分数(分数范围0%~0.5%)的玄武岩纤维混凝土立方体试块在常温和低温下(温度范围20~-90℃)进行了静态劈拉破坏试验。试验结果表明:不同类型混凝土的劈拉强度均随温度降低而线性增大(最大增幅接近130%),呈现出显著的低温增强效应;玄武岩纤维的掺入能略微强化混凝土劈拉强度的低温增强效应。不同纤维体积分数玄武岩纤维混凝土的劈拉强度均呈现出一定的纤维增强效应,并且随体积分数增加而增强;极端低温作用下玄武岩纤维的主导破坏模式由拔出破坏转变为拉断破坏,导致纤维增强效应随温度下降而变强。劈拉强度的尺寸效应随温度下降而更明显,但玄武岩纤维的掺入能减弱尺寸效应(最大削弱程度达25.8%)。本文研究能为玄武岩纤维混凝土材料在极端低温环境下的大规模工程结构应用提供有效参考。

关键词：玄武岩纤维混凝土极端低温纤维含量劈裂拉伸尺寸效应

Analysis of the decrease of two-dimensional electron gas concentration in GaN-based HEMT caused by proton irradiation

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Chinese Physics B 2021年第2期30卷 467-471页

作者： jin-jin Tang Gui-Peng liu Jia-Yu Song Gui-juan Zhao Jian-Hong Yang School of Physical Science and Technology Lanzhou UniversityLanzhou 730000China National&Local Joint Engineering Laboratory of Light-conversion Materials and Technology School of Physical Science and TechnologyLanzhou UniversityLanzhou 730000China

Gallium nitride(Ga N)-based high electron mobility transistors(HEMTs)that work in aerospace are exposed to particles radiation,which can cause the degradation in electrical *** investigate the effect of proton irradiation on the concentration of two-dimensional electron gas(2 DEG)in Ga N-based *** Schr¨odinger’s and Poisson’s equations are solved to calculate the band structure and the concentration of 2 DEG by the self-consistency method,in which the vacancies caused by proton irradiation are taken into *** irradiation simulation for Ga N-based HEMT is carried out using the stopping and range of ions in matter(SRIM)simulation software,after which a theoretical model is established to analyze how proton irradiation affects the concentration of 2 *** by protons with high fluence and low energy,a large number of Ga vacancies appear inside the *** results indicate that the ionized Ga vacancies in the Ga N cap layer and the Al Ga N layer will affect the Fermi level,while the Ga vacancies in the Ga N layer will trap the two-dimensional electrons in the potential *** irradiation significantly reduced the concentration of 2 DEG by the combined effect of these two mechanisms.

关键词： proton irradiation GaN-based HEMT two-dimensional electron concentration