检索结果-南通市图书馆

Deciphering fungal metabolon coupling tandem inverse-electrondemand Diels-Alder reaction and semipinacol rearrangement for the biosynthesis of spiro polycyclic alkaloids

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2025年第1期68卷 288-296页

作者： Shuai Liu Wen-Qiang xu ying-Tong Di man-Cheng Tang Ding-Kang Chen Ming-Ming Cao yao-Wen Chang Hong-Yu Tang Chun-Mao Yuan Jun-Bo Yang Zhi-Li Zuo Han guo Zi-Fei xu ying Zeng Yun-dong Wu Xiao-Jiang Hao Key Laboratory of Phytochemistry and Natural Medicines (Chinese Academy of Sciences) Kunming Institute of Botany Chinese Academy of Sciences University of Chinese Academy of Sciences Lab of Computational Chemistry and Drug Design State Key Laboratory of Chemical Oncogenomics Peking University Shenzhen Graduate School Shenzhen Bay Laboratory State Key Laboratory of Microbial Metabolism School of Life Sciences & Biotechnology Shanghai Jiao Tong University State Key Laboratory of Functions and Applications of Medicinal Plants Guizhou Medical University Molecular Biology Experimental Center Germplasm Bank of Wild Species in Southwest China Kunming Institute of Botany Chinese Academy of Sciences Yunnan Key Laboratory for Wild Plant Resources Kunming Institute of Botany Chinese Academy of Sciences Research Unit of Chemical Biology of Natural Anti-Virus Products Chinese Academy of Medical Sciences

In the intricate process of natural product biosynthesis, a metabolon can enhance metabolic flux by associating sequential enzymes. A fungal metabolon, comprising of flavin-dependent monooxygenase Spe F and P450 monooxygenase Spe G, is identified in the biosynthesis of spiro polycyclic alkaloids(+)-notoamide B and its diastereomer(+)-versicolamide B. Using notoamide E as a substance, Spe F/Spe G metabolon can control the stereoselectivity of its 2,3-epoxidation, followed by hydrogen atom ion at C-17 to generate reactive epoxide tau-m A with dienyl iminium unit. Subsequently,(+)-notoamide B and(+)-versicolamide B are produced via tandem nonenzymatic inverse-electron-demand Diels-Alder reaction and semipinacol rearrangement. This provides the first example of metabolon in the biosynthesis of spiro-prenylated indole alkaloids.

关键词： metabolon Diels-Alder reaction semipinacol rearrangement biosynthesis notoamides spiro polycyclic alkaloids

Synthesis of O6-Corona[3]arene[3]pyridazines and Their Molecular Recognition Property in Organic and Aqueous Media

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2018年第7期36卷 630-634页

作者： yao Lu dong-dong liang zhan-Da Fu Qing-hui guo Mei-Xiang wang Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education) Department of Chemistry Tsinghua University Beijing 100084 China

O6-Corona[3]arene[3]pyridazines were synthesized from the one-pot macrocyclic condensation reaction of 3,6-dichlorotetrazine with 1,4-dihydroquinone derivatives followed by the inverse electron demand Diels-Alder reaction of the tetrazine rings with a cyclopentanone-derived enamine. Conversion of six ester groups within macrocycle into all sodium acetate moieties afforded a water soluble O6-corona[3]arene[3]pyridazine. The coronary macrocycle host formed complexes selectively with organic ammoniums and dinitrile guests in a 1 ： 1 stoichiometric ratio in organic solvents with association constants ranging from （2.96± 0.10）× 10^1 to （2.53±0.33）× 10^5 L·mol^-1. Water soluble O6-corona[3]arene[3]pyridazine was also able to complex strongly with organic ammoniums in water to give an association constant up to （2.67 ± 0.21） × 10^4 L·mol^-1. The pseudo-rotaxane and inclusion structures of the host-guest complexes were revealed by the X-ray crystallography.

关键词： coronarene O6-coronaarenepyridazine inverse electron demand Diels-Alder reaction molecular recognition organic ammonium dinitrile

Temperature distribution and dynamic control of secondary cooling in slab continuous casting

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2009年第6期16卷 626-631页

作者： liang-hang guo Yong Tian man yao Hou-fa Shen School of Materials Science and Engineering Dalian University of Technology Dalian 116023 China Anshan Iron and Steel Group Anshan 114021 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China

To predict and optimize the temperature distribution of slab continuous casting in steady operational state, a three-dimensional model （named ＂offline model＂） based on the heat transfer and solidification theories was developed. Both heat transfer and flux distribution characteristics of the nozzle sprays on the slab were considered, and the complicated boundary conditions, such as spray cooling, natural convection, thermal radiation as well as contact cooling of individual rolls were involved in the model. By using the calibrated caster dependent model factors, the calculated temperature and shell thickness accorded well with the measured. Furthermore, a dynamic secondary water cooling control system was also developed on the basis of a two-dimensional transient heat transfer model （named ＂online model＂） and incremental PID control algorithm to reduce slab surface temperature fluctuation in unsteady state. Compared with the traditional spray table control method, the present online model and dynamic PID control demonstrate a higher capability and flexibility to adjust cooling water flowrate and reduce slab surface temperature fluctuation when the casting speed is changed.

关键词： mathematical model slab temperature dynamic control continuous casting

Fine Mapping and Cloning of the Grain Number Per-Panicle Gene (Gnp4) on Chromosome 4 in Rice (Oryza sativa L.)

在线全文

学校读者我要写书评

暂无评论

Agricultural Sciences in China 2011年第12期10卷 1825-1833页

作者： zhanG zhan-ying LI Jin-jie yao guo-xin zhanG Hong-liang DOU hui-jing SHI Hong-li SUN Xing-ming LI Zi-chao Key Laboratory of Crop Heterosis and Utilization Ministry of Agriculture/Beijing Key Laboratory of Crop Genetic Improvement ChinaAgricultural University Beijing 100193 P.R.China

Grain number per-panicle is one of the most important components for rice yield. Spikelets on the primary and secondary branches determine the grain number per-panicle in rice. In this study, we identified a natural mutant, gnp4, lack of lateral spikelet on the secondary branches in the field condition. In addition, the Gnp4 and Lax1-1 double mutant showed dramatically reduced secondary branches and spikelets in panicle at reproductive stage, and tillers at vegetative stage. By map-based cloning approach, and using four F2 segregating populations, the Gnp4 gene was finally mapped to a 10.7-kb region on the long arm of chromosome 4 in rice. In this region, only one gene was predicted, and genomic DNA sequencing of the 10.7-kb region showed no nucleotide differences between the mutant and wild type. Interestingly, we found that the methylation level of several cytosines in the promoter CpG islands region of the predicted gene in gnp4 were different from the wild type. Thus, we propose that the DNA methylation changes at these sites may induce to decrease expression level of Gnp4, consequently, resulting in phenotypic variation.

关键词： rice gnp4 laxl-1 grain number per-panicle methylation

The acid dissolution characteristics of cadmium fixed by a novel Ca-Fe-Si composite material

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2023年第5期127卷 328-335页

作者： Aijun yao Xiang guo man Zhao Shizhong wang Yetao Tang Rongliang Qiu School of Geography and Planning Sun Yat-sen UniversityGuangzhou 510275China School of Environmental Science and Engineering Sun Yat-sen UniversityGuangzhou 510275China Guangdong Provincial Key Lab of Environmental Pollution Control and Remediation Technology Sun Yat-sen UniversityGuangzhou 510275China Guangdong Provincial Key Laboratory of Agricultural&Rural Pollution Abatement and Environmental Safety College of Natural Resources and EnvironmentSouth China Agricultural UniversityGuangzhou 510642China Guangdong Laboratory for Lingnan Modern Agriculture Guangzhou 510642China

Ca-Fe-Si material(CIS),a novel composite material rich in calcium,iron,manganese and silicon showed marvelous immobilization properties for heavy metal(loid)s in *** elucidate the acid stability of Cd fixed by CIS(CIS-Cd)and the underlying immobilizationmechanisms,the acid dissolution characteristics of CIS-Cdwere investigated by using acid titration method and X-ray diffraction(XRD)*** results showed that CIS-Cd had distinctive acid buffering capacity in different pH *** on the titration curve between dissolution rate of CIS-Cd and pH,CIS-Cd can be divided into non acid-stable Cd(9.4%),moderately acid-stable Cd(22.5%)and acid-stable Cd(68.1%).XRD analysis of CIS-Cd at different pH intervals and the correlation curves of dissolution rates of Cd and concomitant elements indicated that non acid-stable Cdwas mainly bound by carbonate,silicate and sulfate(CdCO_(3),Cd_(2)SiO_(4) and CdSO_(4))or co-precipitated with the corresponding calcium *** acid-stable Cd was mainly bound by magnesium-aluminum-silicon containing minerals or electrically bound bymanganese iron ***-stable Cd remaining undissolved at pHmanganese minerals strongly bound *** was by multilateral fixation mechanisms that Ca-Fe-Si material possessed marvelous immobilization capability for Cd and strong resilience to environmental acidification as *** findings implicated that proper combination of calcium-iron-silicon containing minerals could develop novel promising amendments with high efficiency in heavy metal(loid)s immobilization and strong resilience to environmental change.

关键词： Ca-Fe-Si composite material Acid stability Cadmium Immobilization mechanisms

Recent advances in perovskite/organic integrated solar cells

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第10期40卷 2763-2777页

作者： Qiang guo Chen-Yun wang Tasawar Hayat Ahmed Alsaedi Jian-Xi yao zhan-Ao Tan Henan Institute of Advanced Technology Zhengzhou UniversityZhengzhou 450002China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China NAAM Research Group Faculty of ScienceKing Abdulaziz UniversityJeddah 21589Saudi Arabia Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical TechnologyBeijing 100090China

The integrated perovskite/organic solar cell(IPOSC) is widely concerned as an effective approach to broaden the spectrum of perovskite solar cell(PerSC) by utilizing near-infrared light of lower bandgap organic semiconductor. Compared to tandem solar cells, the IPOSCs eliminate the preparation of the intermediate layer and simplify the manufacturing process, but retain the advantages of wide light harvesting. Meanwhile, the IPOSCs can maintain the open-circuit voltage as high as PerSCs. This review summarizes the recent developments of perovskite materials and low-bandgap organic conjugated materials applied in solar cells. Then, the working mechanism of IPOSCs and the recent developments of IPOSCs based on low-bandgap donor and acceptor materials are highlighted. Besides, the study of charge dynamic in IPOSC is summarized. Finally, the potential of IPOSCs and approach to improve device performance are also envisaged.

关键词： Organic solar cell Perovskite solar cell Perovskite/organic integrated solar cell Conjugated molecules

Growth and Photoluminescence of Epitaxial CeO_(2) Film on Si (111) Substrate

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2001年第3期18卷 443-444页

作者： GAO Fei LI guo-Hua zhanG Jian-hui QIN Fu-Guang yao Zhen-Yu LIU Zhi-Kai wang zhan-guo LIN Lan-ying Laboratory of Semiconductor Materials Science Institute of SemiconductorsChinese Academy of SciencesBeijing 100083 National Laboratory for Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083

CeO_(2) film with a thickness of about 80 nm was deposited by a mass-analyzed low-energy dual ion beams deposition technique on Si(111)*** high-energy electron diffraction and x-ray diffraction measurements showed that the film is a single *** tetravalent state of Ce in the film was confirmed by x-ray photoelectron spectroscopy measurement,indicating that stoichiometric CeO_(2) was ***/blue light emission(379.5 nm)was observed at room temperature,which may be tentatively explained by charge transitions from the 4f band to the valence band of CeO_(2).

关键词： film transitions tentative

Efficient Visual Recognition:A Survey on Recent Advances and Brain-inspired Methodologies

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Machine Intelligence Research 2022年第5期19卷 366-411页

作者： Yang Wu Ding-Heng wang Xiao-Tong Lu Fan Yang man yao Wei-Sheng dong Jian-Bo Shi guo-Qi Li Applied Research Center Laboratory Tencent Platform and Content Group Shenzhen 518057China School of Automation Science and Engineering Faculty of Electronic and Information EngineeringXi′an Jiaotong UniversityXian710049China School of Artificial Intelligence Xidian UniversityXi'an 710071China Division of Information Science Nara Institute of Science and TechnologyNara 6300192Japan Peng Cheng Laboratory Shenzhen 518000China Department of Computer and Information Science University of PennsylvaniaPhiladelphia PA19104-6389USA Institute of Automation Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100190China

Visual recognition is currently one of the most important and active research areas in computer vision,pattern recognition,and even the general field of artificial *** has great fundamental importance and strong industrial needs,particularly the modern deep neural networks(DNNs)and some brain-inspired methodologies,have largely boosted the recognition performance on many concrete tasks,with the help of large amounts of training data and new powerful computation *** recognition accuracy is usually the first concern for new progresses,efficiency is actually rather important and sometimes critical for both academic research and industrial ***,insightful views on the opportunities and challenges of efficiency are also highly required for the entire *** general surveys on the efficiency issue have been done from various perspectives,as far as we are aware,scarcely any of them focused on visual recognition systematically,and thus it is unclear which progresses are applicable to it and what else should be *** this survey,we present the review of recent advances with our suggestions on the new possible directions towards improving the efficiency of DNN-related and brain-inspired visual recognition approaches,including efficient network compression and dynamic brain-inspired *** investigate not only from the model but also from the data point of view(which is not the case in existing surveys)and focus on four typical data types(images,video,points,and events).This survey attempts to provide a systematic summary via a comprehensive survey that can serve as a valuable reference and inspire both researchers and practitioners working on visual recognition problems.

关键词： Visual recognition deep neural networks(DNNS) brain-inspired methodologies network compression dynamic inference survey

Examining the association between delay discounting,delay aversion and physical activity in Chinese adults with type-2 diabetes mellitus

在线全文

学校读者我要写书评

暂无评论

World Journal of Diabetes 2024年第4期15卷 675-685页

作者： Yong-dong An guo-Xia Ma Xing-Kui Cai ying Yang Fang wang zhan-Lin zhang Department of Endocrinology People's Hospital of Linxia Hui Autonomous PrefectureLinxia Hui Autonomous Prefecture 731100Gansu ProvinceChina Department of Gynecology People's Hospital of Linxia Hui Autonomous PrefectureLinxia Hui Autonomous Prefecture 731100Gansu ProvinceChina The First Clinical Medical College Lanzhou UniversityLanzhou 730013Gansu ProvinceChina Department of Internal Medicine People's Hospital of HezhengLinxia Hui Autonomous Prefecture 731200Gansu ProvinceChina Department of Geratology People's Hospital of Linxia Hui Autonomous PrefectureLinxia Hui Autonomous Prefecture 731100Gansu ProvinceChina Department of Medical People's Hospital of Linxia Hui Autonomous PrefectureLinxia Hui Autonomous Prefecture 731100Gansu ProvinceChina

BACKGROUND The role of physical activity in diabetes is critical,influencing this disease's development,man-agement,and overall *** China,22.3%of adults do not meet the minimum level of physical activity recommended by the World Health ***,it is imperative to identify the factors that contributing to lack of physical activity must be *** To investigate the relationship among delay discounting,delay aversion,glycated hemoglobin(HbA1c),and various levels of physical activity in Chinese adults diagnosed with type 2 diabetes mellitus(T2DM).METHODS In 2023,400 adults with T2DM were recruited from the People's Hospital of Linxia hui Autonomous Prefecture of Gansu Province.A face-to-face questionnaire was used to gather demographic data and details on physical activity,delay discounting,and delay *** addition,HbA1c levels were measured in all 400 *** primary independent variables considered were delay discounting and delay *** outcome variables included HbA1c levels and different intensity levels of physical activity,including walking,moderate physical activity,and vigorous physical *** linear regression models were utilized to assess the relationship between delay discounting,delay aversion,and HbA1c levels,along with the intensity of different physical activity measured in met-hours per *** After controlling for the sample characteristics,delay discounting was negatively associated with moderate physical activity(β=-2.386,95%CI:-4.370 to-0.401).Meanwhile,delay aversion was negatively associated with the level of moderate physical activity(β=-3.527,95%CI:-5.578 to-1.476)in the multiple linear regression model,with statistically significant *** Elevated delay discounting and increased delay aversion correlated with reduced levels of moderate physical *** suggests that delay discounting and aversion may influence engagement in moderate physical activity.

关键词： Type 2 diabetes mellitus Delay discounting Delay aversion Physical activity