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1.
用2D NMR技术研究了从银杏叶提取物中分离的一个黄酮双糖甙[槲皮素-3-鼠李糖-(6-对羟基反式桂皮酰)葡萄糖甙]的结构,对鼠李糖部分的^1H NMR,^13C NMR化学位移进行了归属。^13C化学位移和^1H NOE相关性都证明鼠李糖为1″-2″连接。  相似文献   

2.
川续断中新七糖三萜皂苷的核磁共振研究   总被引:2,自引:1,他引:1  
从中药川续断根部的乙醇提取物中分得一个新的三萜皂甙.经过测定,它为:3-O[α-L-吡喃鼠李糖(1→3)][-β-D吡喃葡萄糖(1→4)]-β-D吡喃葡萄糖(1→3)-α-L-吡喃鼠李糖(1→2)-β-L-吡喃阿拉伯糖-常春藤甙元-28-O-β-D-吡喃葡萄糖(1→6)-β-D-吡喃葡萄糖酯甙.本文采用一维SEMDY,旋转坐标NOE差谱和选择性远程DEPT新技术相结合测定该化合物的糖链结构.  相似文献   

3.
缪振春      周永新     《波谱学杂志》1999,16(4):1
从日本续断根部的乙醇提取物中分得一个新的三萜皂苷.经过测定,它为3-O-[βD-吡喃葡萄糖(1→4)][α-L-吡喃鼠李糖(1→3)]-β-D-吡喃葡萄糖(1→3)-α-L-吡喃鼠李糖(1→2)-α-L-吡喃阿拉伯糖-常春藤甙元.结果表明,采用一维SEMDY和旋转坐标NOE差谱核磁共振新技术相结合的方法测定这一类化合物的糖链结构不需要对化合物进行化学降解或衍生化,方法简便、快速,测定结果可靠,每个糖基的  相似文献   

4.
从日本续断根部的乙醇提取物中分得一个新的三萜皂苷.经过测定,它为:3-O-[β-D-吡喃葡萄糖(1→4)][α-L-吡喃鼠李糖(1→3)]-β-D-吡喃葡萄糖(1→3)-α-L-吡喃鼠李糖(1→2)-α-L-吡喃阿拉伯糖常春藤甙元.结果表明,采用一维SEMDY和旋转坐标NOE差谱核磁共振新技术相结合的方法测定这一类化合物的糖链结构不需要对化合物进行化学降解或衍生化,方法简便、快速,测定结果可靠,每个糖基的1H NMR信号可以分辨和明确归属.  相似文献   

5.
用1D及2DNMR技术(COSY,TOCSY,HMQC及HMBC)归属了合成抗孕酮新药RU-486中间体3,3乙撑二氧5α,10α及5β,10β环氧-Δ9(11),雌烯17α(1-丙炔基)17β羟基的1H和13CNMR谱线.  相似文献   

6.
本文采用法拉弟效应的激光磁共振光谱技术,研究了-氧化氮分子14N16OX2Π3/2R(1.5)v=0→1和同位素分子15N16OX2Π3/2Q(1.5)v=0→1跃迁的FLMR光谱,实验给出了样品浓度和信号强度之间的关系及调制磁场强度与FLMR信号强度之间的关系。  相似文献   

7.
本文采用法拉弟效应的激光磁共振光谱技术,研究了一氧化氮分子^14N^16OX^2П3/2R(1.5)v=0→1和同位素分子^15^16OX^2П3/2Q(1.5)v=0→跃迁的FLMR光谱,实验给出了样品浓度和信号强度之间的关系及调制磁场强度与FLMR信号强度之间的关系 。  相似文献   

8.
基于多体展式方法所导出的NO2(X2A1)的分析势能函数[1],用准经典的Monte-Carlo轨迹法研究了O(3Pg)+NO(X2II)和N(3Du)+O2(X3∑-g)的原子与分子反应动力学。研究结果指出,反应O(3Pg)+NO(X3II)→NO2(X2A1)的阈能值约为2kcal/mol,而反应N(2Du)+O2(X3∑-g)→NO(X3II)+O(3Pg)是无阈能的。对后者,随初始平动能的增加,反应产物的向前散射减少,在160kcal/mol时达到极小,之后又缓慢增加。  相似文献   

9.
采用1H-1HCOSY,HMQC、HMBC等2DNMR技术对化合物(Et4N)2[Pd2(mp)2(μ-mpH)2]进行1H、13CNMR谱数据分析与归属.表明它在DMSO溶液中仍保持原有固体状态的分子结构.  相似文献   

10.
雷公藤精(Wilforgine)的2D NMR研究   总被引:1,自引:1,他引:0  
用2D NMR(^1H-^1HCOSY,^1H-^13C COSY,TOCSY,NOESY和COLOC)技术研究了从雷公藤中分离到的雷公藤精,对^1H和^13C谱进行了归属。  相似文献   

11.
Results of radionuclide activity concentration measurements in deposition and ground-level air conducted at the station of the Institute of Physics situated 3.5 km from the Ignalina Nuclear Power Plant (Ignalina NPP) in 2005 are analyzed. Atmospheric depositional fluxes of 7Be, 60Co and 137Cs are estimated. Radionuclide particle deposition rates are calculated. The Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model of the global dispersion and deposition is used to explain variations in the 137Cs activity concentration in the ground-level air in the Ignalina NPP region in 2005. An increase in the 137Cs activity concentration of up to 17.4 μBq m−3 on 30 October-5 November is studied. Modelling results show that the Chernobyl NPP Unit 4 Sarcophagus and the radiocaesium resuspension from the Chernobyl NPP accident polluted regions are sources of 137Cs to the environment of the Ignalina NPP. Results on solubility in water of aerosols — carriers of 137Cs — are discussed.  相似文献   

12.
In this paper, we investigate the data of industries in China and find that the frequency distributions of fixed assets and fixed-assets’ investment of industries obey power laws. We show that these power-law modes can be explained by the rules of the Simon Model, rather than the existing investment theories such as the classical investment theory or acceleration principle. Moreover, the mechanism of the investment distribution may be similar to the forest-fire model of self-organizing criticality. By introducing the complex system methods, this research changes the traditional opinion of the investment and gains some meaningful understanding in the dynamics of industries and the economic cycle.  相似文献   

13.
The role of strong absorption of particles in intermediate and final states has been considered. The range of applicability of phenomenological models of absorption has been studied. This model is nonuniversal. Its applicability depends on the type of interaction Hamiltonian and matrix element used. We also demonstrate that the violation of the unitarity condition can produce a qualitative error in the results. The absorption (decay) in the final state does not tend to suppress the total process probability as well as the probability of the channel corresponding to absorption. This is true for the reactions, decays and nˉ conversion in the medium.  相似文献   

14.
室内声学中散射研究进展   总被引:1,自引:0,他引:1       下载免费PDF全文
刘海生  龚农斌 《应用声学》2005,24(2):126-132
近20年,界面散射研究在声场预测、定量测量和产品研发等方面取得了重要进展,加深了我 们对散射及其作用的认识。人们可以定量地评估、设计和优化散射产品,用更加丰富的手法进行室内 音质设计。  相似文献   

15.
Summary  The recently discovered plateau and rings in high-order multiphoton ionization apparently have their origin in rescattering. Similarly, rescattering is involved in higher-order harmonic generation. Using a simple one-dimensional model, it is shown that the phase-coherence in this rescattering process is of considerable importance. The authors of this paper have agreed to not receive the proofs for correction. This work has been supported by the East-West Program of the Austrian Academy of Sciences and by the Austrian Ministry of Science and Transportation under project no. 45.372/2-IV/6/97. One of us (JZK) acknowledges the support of the Polish Committee of Scientific Research (grant KBN 2 P03B 007 13).  相似文献   

16.
化学诱导动态电子极化(CIDEP)是检测瞬态顺磁粒子并表征其特征的强有力的手段,对于研究光化学和光物理瞬态过程的微观机理和规律有重要意义. 本文较为详细地总结了4种常见的CIDEP机理,讨论了各种极化谱及相应的极化条件;简要介绍了国内研究小组在CIDEP理论以及在均相溶液和微复相体系中光化学过程的CIDEP研究成果.   相似文献   

17.
IR spectra of acetonitrile embedded in an argon matrix and in a liquid are recorded. IR spectra of specimens obtained with different concentrations of acetonitrile in argon are analyzed. The spectral region of C≡N vibrations of 2200–2300 cm−1 with bands of monomers and possible associates is investigated. Overlap with the band of a hot transition on the low-frequency side is responsible for the pronounced asymmetry of the band ν(C≡N). To whom correspondence should be addressed. St. Petersburg State Institute of Precision Mechanics and Optics (Technical University), 14, Sablinskaya Str., St. Petersburg, 197101, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 5, pp. 627–631, September–October, 1999.  相似文献   

18.
19.
Efficient frequency-doubling is experimentally demonstrated in presence of beam self-trapping in congruent lithium niobate crystal. The self-trapping is induced by the generated second harmonic beam via photorefractive effect under an external applied field. The local space charge field distribution, formed by the second harmonic beam, is shown to efficiently trap both wavelengths. The dynamics of self-focusing is studied along with the power evolution of the second harmonic beam. Fast tuning of phase matching conditions in the written waveguide is realized by an externally applied voltage also used for the photorefractive confinement.  相似文献   

20.
R Pratap 《Pramana》1987,29(3):231-245
An electron gas in crossed electric and magnetic fields of arbitrary strength is considered in the framework of nonequilibrium statistical mechanics. It is known that more than one independent frequency existing in a system, which are of comparable magnitude, can generate coherent synergic radiation. In the present system three independent frequencies exist: viz the synchrotron frequency due to the magnetic field, the hopping frequency due to the electric field, and the plasma frequency. It is shown that all these can combine to generate a new synergic coherent radiation. The results also show the possibility of interpreting the quantum nature of Hall conductance as due to density function alone. Besides these, the solution admits the Schubnikov-de Haas oscillation of the electrical conductivity due to change in the fields.  相似文献   

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