排序方式: 共有65条查询结果,搜索用时 78 毫秒
31.
动力学荧光法测定溴离子的研究 总被引:9,自引:0,他引:9
利用溴离子对溴酸钾氧化荧光素的催化作用,建立了动力学荧光法测定微量Br^-的新方法,方法的检出限为1.94×10^-2μg/mL,线性范围为6.0~12.0μg/25mL,将方法用于溴吡斯的明药片中Br^-含量的测定,结果满意。 相似文献
32.
观测到一种以Tb3+-Er3+进行光谱转换的量子剪裁现象。一个高能紫外光子(Tb3+的7F6→5L1)被量子剪裁成两个低能光子:一个是近红外光子(Er3+的4I9/2→4I15/2),另一个是蓝色光子(Tb3+的5D4→7F6),它们两个 都可以被GaAs太阳能电池有效地吸收。量子剪裁效率高达188%,接近理论极限的200%。从Tb3+(5L1→ 5D4) 到Er3+(4I15/2→4I9/2)的能量传递的能量失配是237 cm-1,比NaYF4中的声子能400 cm-1小,能量传递是近共振的。Tb3+施主间的能量迁移可以近似地用扩散模型处理, 从Tb3+-Er3+对之间能量传递的初始过程发现,偶极-偶极相互作用占主导地位。 相似文献
33.
S. Prince Makarios Paul D. Parimala devi G. Praveena R. Jeba Beula M. Haris A. Abiram 《印度化学会志》2022,99(3):100368
We have theoretically studied the interaction of a commonly used drug, Metformin, with the herb, Ferulic acid, applying density functional theory (DFT). The complex was optimized at various positions and confirmed to be in their local minima through vibrational analysis at B3LYP/6–311++G7 level. Study on the molecular geometry along with the interaction energy of the complexes confirmed the presence of interaction between the hydroxyl and amine group of the herb and drug respectively. The calculation of Gibbs free energy and entropy exhibited the stability of the interacting structures along with the vibrational assignment which showed significant red and blue shifts in the complexes. Additionally, NBO analysis and molecular electrostatic potential (MEP) revealed the charge transfer between the complexes identifying an electrostatic interaction prevailing between the herb and drug. 相似文献
34.
朱砂有凉性、解热、收敛作用,一般以粉末状入药于中药或蒙药中。然而朱砂具有一定的毒性,因此有必要对药品中朱砂的含量进行检测分析。利用便携式拉曼光谱仪对朱砂进行了鉴别分析,获得了朱砂较为全面的分子结构振动信息。实验结果显示朱砂的拉曼光谱在253,290和343 cm-1等处出现了较强的拉曼特征峰,文中确定以此三处特征峰作为研究对象。同时,检测了蒙药八味止血红花散、朝伦-雄胡-5、外用溃疡散以及中药口腔溃疡散的拉曼光谱。结果在含有朱砂的几种蒙药八味止血红花散、朝伦-雄胡-5和外用溃疡散均检测到了朱砂的特征峰,而在不含有朱砂的中药口腔溃疡散中未检测到拉曼特征峰。此外,对口腔溃疡散中的朱砂进行半定量分析,检测极限可达到质量分数的10%左右。拟合得到了中药口腔溃疡散的拉曼光谱特征峰强度与其中朱砂的掺杂量之间的关系,获得曲线的相关系数r=0.995 9,验证了拟合结果的准确性。该拉曼光谱检测方法具有快速、简便、准确等优点,值得在中蒙药成分鉴定方面得到广泛的应用。 相似文献
35.
研究任意广义Bethe树指标马尔可夫链场二元泛函关于广义随机选择系统的一类局部极限定理.作为推论得到了广义随机选择系统中任意Cayley树上状态频率和状态序偶的一类极限定理.证明中采用了一种研究马尔可夫链场的较新颖的分析方法. 相似文献
36.
HPLC法同时测定石蒜中加兰他敏和石蒜碱 总被引:3,自引:0,他引:3
建立了高效液相色谱同时测定石蒜中加兰他敏和石蒜碱含量的方法。 采用phenomenex-C18色谱柱,以乙腈(A)-0.1%TFA水溶液(B)为流动相梯度洗脱,检测波长289 nm。 结果表明,加兰他敏和石蒜碱均在0.5~10 mg/L(r=0.9999)呈现良好的线性关系,最低检测限(S/N=3)分别为0.09和0.15 mg/L,平均加样回收率分别为99.53%和96.82%。 该方法简单、快速、准确,适合于石蒜中加兰他敏和石蒜碱的测定。 相似文献
37.
Six ent-kaurene type diterpenoids were isolated from the leaves of Rabdosia nerwsa. Among them.ganer-vosin A and B are new compounds, the structures of which were elucidated as 1 and 2 respectively by spectral and chemical methods. The other four were identified as odonicin (3), novelrabdosin (4), nodosin (5) and shikokianal acetate (8). Compounds (1), (2), (5) and (8) have not been found in this herb previously. 相似文献
38.
Formation of amorphous phase by solid state reaction has been observed in bulk copper-zirconium couples. Transmission electron
microscopy (TEM), Auger electron spectroscopy (AES) and differential scanning calorimetry (DSC) techniques have been employed
to detect and study the amorphous phase. The experimental observations have been explained with a model, which considers the
breakdown of the a-zirconium lattice due to the solute enrichment beyond a certain limit where the nucleation of the amorphous
phase becomes thermodynamically possible. The present-experiments convincingly show that amorphous phase can form in bulk
diffusion couples made from large-grained well-annealed material and conclusively establish that the presence of crystal defects
in high concentrations is not a pre-requisite for the formation of amorphous phase. 相似文献
39.
The spatial decay behavior of solutions of a coupled system of second-order quasilinear partial differential equations, in
divergence form, defined on a two-dimensional semi-infinite strip, is investigated. Such equations arise in the theory of
anti-plane shear deformations for isotropic nonlinearly thermoelastic solids. Differential inequality techniques are employed
to obtain exponential decay estimates. The results are illustrated by several examples. The results are relevant to Saint-Venant
principles for nonlinear thermoelasticity as well as to theorems of Phragmen-Lindelof type.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
40.