三七中2个微量人参皂苷的NMR信号全归属

从三七根的80%乙醇提取物中,分离并鉴定了2个人参皂苷类化合物,分别为6-O-(β-D-glucopyranosyl)-20-O-(β-D-xylopyranosyl)-3β,6α,12β,20(S)-tetrahydroxydammar-24-ene(化合物1)和notoginsenoside U(化合物2).应用1D和2D NMR(1H-1H COSY、HSQC和HMBC)对这2种化合物的结构进行解析,对化合物1的13C NMR文献报道数据进行了修正与讨论,并对化合物1的1H NMR数据进行全归属.同时在2D NMR的基础上对化合物2在氘代吡啶溶液中的1H NMR和13C NMR数据进行全归属.     

Nonlinear acoustics: from research in physics to application (historical incidents)

The subject of nonlinear acoustics (NA) is the strong perturbations of medium, which doesn’t obey the princip of superposition. The manyfold interactions of sound with different perturbations of medium are developing in this case. Fast development of NA took place in the second part of the last centure due to ultrasonic technology progress, which provides high intensity ultrasound generation. Some incidents of NA development, connected with study of high intensity sound propagation and application of Parametric Arrays are presented in the present paper.     

Specific heat,cell parameters,phase T - p diagram,and permittivity of cryolite (NH 4 ) 3 Nb(O 2 ) 2 F 4

The temperature dependences of the specific heat, unit cell parameters, susceptibility to hydrostatic pressure, and permittivity of cryolite (NH₄)₃Nb(O₂)₂F₄ have been studied. Phase transitions of nonferroelectric nature have been detected. Entropy parameters point to the relation of structure distortions to ordering processes.