检索结果-南通市图书馆

Organocatalytically Enantioselective Approach to Polysubsti- tuted Tetrahydropyridines and Piperidines

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2011年第9期29卷 1873-1879页

作者： yu, fang Zhang, Xiaojing Jiang, Yongwen Shenyang Pharmaceutical University 103 Wenhua Lu Shenyang Liaoning 110016 China State Key Laboratory of Bioorganic and Natural Products Chemistry Shanghai Institute of Organic Chemistry Chinese Academy of Sciences Shanghai 200032 China

A convenient and highly enanfioselecfive method for assembly of functionalized 1,2,3,4,5-pentasubstituted tetrahydropyridines and piperidines was developed. This method relies on preparing the required enantiopure cyclic semi-acetals via an organocatalyzed Michael addition/cyclization cascade reaction of aldehydes and a-keto-α,β- unsaturated esters, and subsequent reductive amination/condensation with primary amines.

关键词： organocatalysis Michael addition reductive amination substituted piperidine tetrahydropyridine

Effects of the Spatial Coupling of Water and Fertilizer on the Chlorophyll Fluorescence Parameters of Winter Wheat Leaves

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Agricultural Sciences in China 2011年第12期10卷 1923-1931页

作者： SHEN yu-fang LI Shi-qing State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau/Northwest A＆F University Yangling 712100 P.R.China

Wheat is an important agricultural crop in the Loess region of China, where there is drought stress and low availability of soil nitrogen and phosphorus. Using a pulse modulation fluorometer, we studied the effects of water, nitrogen, and phosphorus on the kinetic parameters of chlorophyll fluorescence in winter wheat. The wheat was grown in layered columns of Eum-Orthic Anthrosol （Cinnamon soil）, with the water content and nutrient composition of each layer controlled. The results showed that the kinetic parameters of chlorophyll fluorescence were sensitive to water stress. The basic fluorescence （F0） of leaves was higher in the dry treatment （0-30 cm layer at 40-45% of field capacity, 30-90 cm at 75-80% of field capacity） compared to the wet treatment （entire soil column at 75-80% of field capacity）. The maximal fluorescence （Fm）, the variable fluorescence （Fv）, the photochemical efficiency （Fv/Fm） and potential activites （Fv/F0） of photosystem 2 （PS2） were significantly lower in the dry treatment. Although drought stress impaired PS2 function, this effect was significantly ameliorated by applying P or NP fertilizer, but not N alone. P application increased FJFm, both in well-watered and water stressed plants, especially when fertilizer was applied throughout the column or within the top 30 em of soil. A combined fertilizer improved photosynthesis in well watered plants, with Fm and F,fFm being the highest when fertilizer was applied throughout the columns. For drought stressed, plants FJFm was significantly greater when combined fertilizer was added within the top 30 cm of soil. We concluded that, when growing winter wheat in both arid and semi-arid parts of the Loess region of China, it is important to guarantee the nutrient supply in the top 30 cm of the soil.

关键词： water stress nutrient spatial coupling chlorophyll fluorescence column experiment

Recent progress in microRNA study:Benefits from technique advance

在线全文

学校读者我要写书评

暂无评论

Science China(Life Sciences) 2012年第7期55卷 649-650页

作者： yu Jia WANG fang Department of Biochemistry and Molecular Biology National Laboratory of Medical Molecular Biology Peking Union Medical College & Chinese Academy of Medical Sciences Beijing 100005 China

Over the last decade, sequencing of different genomes re- vealed that an increase in organismal complexity is not merely explained by a dramatic increase in the number of protein-coding genes. However, the gradual increase in protein diversity contributes a lot to the complexity of high- er organisms [1]. It is now widely accepted that non-coding RNAs （ncRNAs）, especially microRNAs （miRNAs） largely define eukaryotic cell functions and the impacts of a variety of gene regulation [2].

关键词：小分子RNA 技术进步蛋白编码基因非编码RNA 基因组测序 miRNA 细胞功能微RNA

A novel machine learning approach(svm Somatic) to distinguish somatic and germline mutations using next-generation sequencing data

在线全文

学校读者我要写书评

暂无评论

Zoological Research 2021年第2期42卷 246-249页

作者： yu-fang Mao Xi-Guo yuan yu-Peng Cun School of Computer Science and Technology Xidian UniversityXi'anShaanxi 710071China iFlora Bioinformatics Center Germplasm Bank of Wild SpeciesKunming Institute of BotanyChinese Academy of SciencesKunmingYunnan 650201China

DEAR EDITOR,Somatic mutations are a large category of genetic variations,which play an essential role in tumorigenesis. Detection of somatic single nucleotide variants(SNVs) could facilitate downstream analysis of tumorigenesis. Many computational methods have been developed to detect SNVs, but most require normal matched samples to differentiate somatic SNVs from the normal state, which can be difficult to obtain.

关键词： data A novel machine learning approach svm Somatic

Studying the Fermi GeV light curve of Vela with the two-pole caustic model

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2009年第12期9卷 1324-1330页

作者： Huan yu Jun fang Ze-Jun Jiang Department of Physics Yunnan University Kunming 650091 China

An observation of the Vela pulsar with the Fermi Large Area Telescope has been recently reported and the GeV light curve shows two main peaks with a phase separation of ～0.43. We study the GeV light curve using the two-pole caustic model in which the peaks of the light curves of the pulsar result from caustic effects. The results show that the two-pole caustic model can reproduce the observed emission pattern of the two peaks and the bridge emission between them well, but overestimates the flux outside the two peaks. After taking account of the pair production effect on the azimuthal angle, we find that the resulting light curve is more consistent with the observation. We excluded the emissions from the field lines for which the distance from the null charge surface, where the pairs can be significantly produced, is larger than the radius of the light cylinder.

关键词： gamma rays: theory -- pulsars: individual (PSR B0833-45)

Room-temperature ferromagnetism enhancement in Fe-doped VSe2nanosheets synthesized by a chemical method

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2021年第9期40卷 2501-2507页

作者： Li-Yan Hu Li-fang yu Huan Yang Xian Xu fang Wang Xiao-Hong Xu School of Chemistry and Materials Science Shanxi Normal UniversityLinfen 041004China Key Laboratory of Magnetic Molecules and Magnetic Information Materials Ministry of EducationLinfen 041004China Research Institute of Materials Science Shanxi Normal UniversityLinfen 041004China Collaborative Innovation Center for Shanxi Advanced Permanent Magnetic Materials and Technology Linfen 041004China

Two-dimensional(2 D)few-layerVSe_(2),V_(1-x)Fe_(x)Se_(2) nanosheets have been synthesized by a hightemperature organic solution-phase method. The thickness of VSe_(2) nanosheets can be tuned from 12 to 5 layers by decreasing the precursor concentrations. The few-layer VSe_(2) nanosheets show the room-temperature ferromagnetism. The coercivity and magnetization reach 0.024 T and 0.036 mA·m^(2)·g^(-1) at room temperature. The chargedensity wave behavior is also confirmed in VSe_(2) by the hysteresis loops and zero-field-cooling curve. V_(1-x)Fe_(x)Se_(2) nanosheets can be obtained by doping Fe(acac)3 in the reaction process. The room-temperature coercivity and magnetization of V_(0.8)Fe_(0.2)Se_(2) nanosheets are 5 times higher than those of the pure VSe_(2) nanosheets without destroying the structures. The enhancement of magnetization is due to the coupling interaction of 3 d orbits between V and Fe atoms. Higher Fe concentration is beneficial to improve the coercivity, which is attributed to the formation of the second phase Fe3 Se4. This simple chemical preparation method can be extended to prepare the other 2 D materials.

关键词： VSe2 Fe doping Two-dimensional nanosheets Room-temperature ferromagnetism Chemical method

The Death of an Auteur:Qiu Huadong’s Confessionat Noon and the Spiritual Crisis of Intellectuals

在线全文

学校读者我要写书评

暂无评论

Frontiers of Literary Studies in China-Selected Publications from Chinese Universities 2020年第1期14卷 76-98页

作者： fang-yu LI Division of Humanities New College of FloridaFL 34243USA

Written by Qiu Huadong in 2000,Confession at Noon(Zhengwu de gongci)is a novel about the life of a renowned auteur one year after his *** at the end of the twentieth century,the story highlights the social and political change of the 1990s and its impact on the spiritual condition of *** novel also addresses the changing role of writers as they confront new challenges presented by the rapid modernization and economic progress at the turn of the *** this paper,I illustrate the ways in which Qiu unravels the spiritual agony of intellectuals through the portrayal of a film director’s dramatic life.I focus particularly on how Qiu uses narrative devices such as intertexuality and pastiche to illuminate the spiritual crisis and changing social position of intellectuals in the 1990s,and how he inserts fictional selves in the storytelling process to rethink his role as a writer-intellectualin the new era.

关键词： Qiu Huadong intellectuals writers identity spiritual crisis

Resonant surface plasmons of a metal nanosphere treated as propagating surface plasmons

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2018年第6期27卷 406-409页

作者： yu-Rui fang Xiao-Rui Tian Key Laboratory of Materials Modification by Laser Electron and Ion Beams （Ministry of Education） School of Physics Dalian University of Technology Dalian 116024 China Bionanophotonics Department of Applied Physics Chalmers University of Technology SE-412 96 Goteborg Sweden Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link 637371 Singapore

On the assumption that the resonant surface plasmons on a spherical nanoparticle are formed by standing waves of two counter-propagating surface plasmon waves along the surface, by using Mie theory simulation, we find that the dispersions of surface plasmon resonant modes supported by silver nanospheres match with those of the surface plasmons on a semiinfinite medium-silver interface very well. This suggests that the resonant surface plasmons of a metal nanosphere can be treated as a propagating surface plasmon wave.

关键词： surface plasmons surface waves scattering of particles dispersion relations

Ab initio Study on Ionization Energies of 1-Methyl-hypoxanthine

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Physics 2012年第5期25卷 540-544,I0003页

作者： Ke-dong Wang Da-peng Yang yu-fang Liu College of Physics and information Engineering Henan Normal UniversityXinxianE 453007China College of Mathematics and Information Science North China University of Water Resources andElectric PowerZhengzhou 450011China

Six low-lying tautomers of 1-methyl-hypoxanthine have been studied at the B3LYP/aug-cc- pVDZ level. Two tautomers NTH and N9H with the comparable energies are far more stable than the others. The vertical ionization energies of the tautomers calculated with ab initio electron propagator theory in the P3/aug-cc-pVDZ approximation are in agreement with the experimental data from photoelectron spectroscopy. According to the calculated relative energies and the comparison between the simulated and the experimental photoelectron spectra, it demonstrates that there are at least two tautomers of 1-methyl-hypoxanthine in the gas-phase experiments.

关键词： Tautomer Ionization energy Relative energy Photoelectron spectrum