四氢β—咔啉类化合物的~(13)C NMR研究

测定了四对新合成的四氢β-咔啉化合物的~13C NMR谱,通过APT,HETCOR和HETCOLOC谱指认了所有碳的归属.所确定的化学位移规律可以用来确定它们的构型.     

三种胺羧配合物的113Cd NMR研究

该文对Cd-HEDTA(N-(2-羟基乙基)乙二胺-N',N',N'-三乙酸),Cd-PDTA(1,2丙二胺四乙酸)和Cd-DTPA(二乙三胺五乙酸)的¹¹³Cd NMR谱和自旋晶格弛豫时间T₁,及NOE因子进行了研究.结果表明,Cd-HEDTA和Cd-PDTA结构与Cd-EDTA类似,Cd-PDTA双线归因于其可能的两种异构体.Cd-DTPA大的化学位移表明其具有七配位的五角双锥结构.在这种结构中DTPA可用三个氮原子参加配位.对¹¹³Cd自旋晶格弛豫时间分析表明,Cd-DTPA配合物中质子偶极作用机理的贡献较大,这归因于Cd DTPA有更多的乙酸根亚甲基质子参与偶极作用.     

A Pair of Dimeric Stilbene Epimers from Gnetum Montanum

GnetummontanumofgnetaceaisdistributedinsouthernChina.AsaChinesefOlkmedicine,itslianasareusedtotreatbronchitisandarthritis'.Previousinvestigationofthisspeciesledtotheisolationofsomealkaloidsanddibenzyletherde,i.ati.es2.lnourstudies,tenknowncomponentsincludingresveratrol,isohapontigenin,daucosterol,6-sitosterol,stearicacid,gnetifolinE,gnetol,isorhapontigenin-3-O-6-glucopyra(-)E-viniferinandgnetifolinCwereisolatedfromthesameresource.Atthesametime,apairoftraceepimerswereobtained.Thisisthefirste…     

Mass Spectral Fragmentation of (S,S)-N,N′-Bis [1-(hydroxymethyl)alkyl]anthracene/Naphthalene-1,8-dicarboxamides under Electron Impact Ionization Conditions

IntroductionN,N′-Bis [1-( hydroxymethyl) alkyl] dicarboxa-mides are important intermediates for the syntheses ofbis-oxazolines, which are a class of the most importantand widely used ligands in catalytic asymmetric reac-tions[1,2]. On determining the str…     

Multiple doubly periodic solutions of semi-linear damped beam equations

The purpose of this work is to investigate the weakened Ambrosetti–Prodi type multiplicity results for weak doubly periodic solutions of damped beam equations. By using the topological degree theory, the author obtains a result which is similar to the result for damped wave equations in the literature.     

Yb:FAP和Yb:C3S2-FAP晶体光谱的温度特性和选择激发

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Frequency-stabilized semimonolithic frequency doubler with high output power

We present a semimonolithic frequency-doubler from 1080 to 540 nm with 80% doubling efficiency and up to 849-mW output power of green light.     

三种群食物链交错扩散模型的整体

本文应用能量估计方法和Gagliardo-Nirenberg型不等式证明了一类强耦合反应扩散系统整体解的存在性和一致有界性，该系统是带自扩散和交错扩散项的三种群Lotka-Volterra食物链模型．通过构造Lyapunov函数给出了该模型正平衡点全局渐近稳定的充分条件．     

光电倍增管脉冲性能研究

采用外腔式电光开光,调制主动照相探测光源,使光电倍增管处于脉冲工作状态下,以提高光电倍增管的输出幅度和动态范围,改善信号的信噪比,同时避免样品和探测器受长时间强激光照射.对滨松H6780光电倍增管进行了调试,使其线性输出电流由静态的0.1mA提升到脉冲状态的4.4mA,信噪比提高4.5倍.该技术对其他光敏探测有借鉴意义.