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961.
稀土Eu3+能与甲磺酸帕苏沙星形成络合物,并发出Eu3+的特征荧光.加入表面活性剂SDBS能大大增强体系的荧光强度,由此建立了表面活性剂敏化的Eu3+荧光探针测定甲磺酸帕苏沙星的方法.最佳测定条件为最大激发和发射波长分别是332和618 nm;pH=7.5;Eu3+浓度为1.2×10-5 mol/L,SDBS浓度为3.0×10-5 mol/L.甲磺酸帕苏沙星浓度在3.0×10-8~2.0×10-6 mol/L范围内与荧光强度线性关系良好,r=0.9993;检出限为1.0×10-9 mol/L.该方法用于甲磺酸帕苏沙星注射剂和人体血清以及尿样中的甲磺酸帕苏沙星的含量测定,结果令人满意. 相似文献
962.
the interaction of hemin with chloroquine,quinine and quinidine was investigated in 50% water-propylene glycol mixture at pH=9,8.1,7.4 and 6.8using a spectrophotometric method.The data could be well fitted into a model consistent with the formation of a 1:1 complex between the reacting partners.In addition,the results indicated that hemin complexed more strongly with quinidine than with chloroquine and quinine,and the binding constants were pH-dependent.Moreover,it was proved that the water-propylene glycol mixture is well suitable to the study of the systems containing hemin and quinolinebased drugs. 相似文献
963.
Ingo Hartenbach Falk Lissner Tanja Nikelski Steffen F. Meier Helge Müller‐Bunz Thomas Schleid 《无机化学与普通化学杂志》2005,631(12):2377-2382
About Lanthanide Oxotantalates with the Formula MTaO4 (M = La – Nd, Sm – Lu) Besides being a by‐product of solid state syntheses in tantalum ampoules the lanthanide(III) oxotantalates of the formula MTaO4 can be easily prepared by sintering lanthanide sesquioxide M2O3 and tantalum(V) oxide Ta2O5 with sodium chloride as flux. Under these conditions two structure types emerge depending upon the M3+ cationic radius. For M = La – Pr the MTaO4‐type tantalates crystallize in the space group P21/c with lattice constants of a = 762(±1), b = 553(±4), c = 777(±4) pm, β = 101(±1)° and four formula units per unit cell. With M = Nd, Sm – Lu, the monoclinic cell dimensions (space group P2/c) shrink to the lattice constants like a = 516(±9), b = 551(±9), c = 534(±9) pm, β = 96.5(±0.3)° and there are only two formula units present. Both structures show a coordination sphere of eight oxygen atoms for the lanthanide trications shaped as distorted square antiprism for the structure with the larger lanthanides (in the following referred to as A‐type) and as trigonal dodecahedron for the structure with the smaller ones (called as B‐type in the following). The coordination environment about the Ta5+ cations can be described as a slightly distorted octahedron (CN = 6) for the A‐type structure of MTaO4 and a heavily distorted one (CN = 6) for the B‐type. The difference between the two types results from the interconnection of these [TaO6]7? octahedra. Whereas they are connected via four vertices to form corrugated layers according to parallel the bc‐plane in the A‐type, the octahedra of the B‐type MTaO4 structure share edges to built up zig‐zag chains along the c axis. 相似文献
964.
“软平板印刷”微结构制备技术为微米和亚微米器件的制备提供了一条新的途径 [1] ,已被电子学家和材料学家所应用 ,近年来进入了生物学领域[2 ] .本实验室将这一方法与生物分子电子学相结合 ,提出了用于 DNA芯片在片合成的分子印章法 [3,4 ] .分子印章法的实质是接触压印与组合化学相结合的固相界面反应 .聚二甲氧基硅氧烷 ( PDMS)是一种软印刷的优良材料 [5] ,但是由于其疏水性和较差的机械性能 ,必须对其进行改性才能用来制备 DNA分子印章 [6 ] . 聚氨酯作为一种功能材料 ,由于分子中交替的软、硬链段及其不同的热动力学性能而形成… 相似文献
965.
B. Montanari B. Civalleri C. M. Zicovich‐Wilson R. Dovesi 《International journal of quantum chemistry》2006,106(7):1703-1714
The equilibrium structural parameters, high‐ and low‐frequency dielectric tensors, Born effective charges, and Γ‐point vibrational frequencies of bulk Al2O3 corundum are calculated by using the periodic, ab initio program CRYSTAL, which adopts an all‐electron Gaussian‐type basis set. The effect of basis set and the performance of three different functionals, i.e., LDA, PW91, and B3LYP, are discussed. The mean absolute deviation from the measured frequencies is as small as 7 cm?1 for both the LDA and B3LYP functionals, indicating that these functionals perform extremely well in this case. The mean absolute deviation increases to 18 cm?1 when the PW91 functional is used. All three functionals reproduce the equilibrium geometry of corundum to a high level of accuracy, with LDA and B3LYP outperforming PW91 slightly. The comparison of the current all‐electron calculations with previous plane‐wave, pseudo‐potential calculations shows an overall similar performance. The results of isotopic substitution for both Al and O are also presented. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 相似文献
966.
967.
[reaction: see text] Modulation of the fluorescein fluorescence in the presence of spiropyran and ferric ion by light was observed. Such fluorescence modulation was due to the low oxidation potential of complex MC.Fe(2+), which made the electron transfer from MC.Fe(2+) to Flu(+)()(*)() thermodynamically favorable. As a result, the communication between two molecular switches based on fluorescein and spiropyan, respectively, was realized via the reversible Fe(III)/Fe(II) redox couple. The communicating behavior corresponds well to the function of an INHIBIT logic gate. 相似文献
968.
Further studies on the bark of Taiwania cryptomerioides found four new podocarpane derivatives, 1beta,13-dihydroxy-8,11,13-podocarpatriene (1), 14,18-dihydroxy-13-methoxy-8,11,13-podocarpatriene (2), 1beta,14-dihydroxy-13-methoxy-8,11,13-podocarpatriene-2,7-dione (3), and 3beta,14-dihydroxy-13-methoxy-8,11,13-podocarpatrien-7-one (4), together with a known 1beta,13,14-trihydroxy-8,11,13-podocarpatrien-7-one (5). Those structures were elucidated principally from spectral evidence. 相似文献
969.
Superabsorbent hydrogel composites 总被引:1,自引:0,他引:1
A new cost‐effective approach to enhance gel strength of superabsorbent hydrogels was invented. Superabsorbent hydrogel composites (SHCs) were prepared through an optimized rapid solution polymerization of concentrated partially neutralized acrylic acid in the presence of a crosslinking agent under normal atmospheric conditions. Kaolin was used as an inorganic component in the polymerization process to strengthen the hydrogel products. FT‐IR spectroscopy was used to confirm grafting of acrylic chains on to the surface of kaolin particles. Morphology of the products was studied by scanning electron microscopy (SEM). Compared with the kaolin‐free hydrogel (control), kaolin caused a reduced equilibrium swelling and swelling rate as low as 17–31% and 19–29%, respectively. Kaolin, however, resulted in enhanced gel strength as high as 21–35% compared to the control. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to study thermal properties of the composites. The SHCs exhibited higher thermal stability than the control. Meanwhile, changes in certain thermal transitions reconfirmed the chemical interaction of the acrylic chain with kaolin. These thermostabilized strengthened superabsorbent hydrogels may be considered as good candidates for agricultural application to retain more water under soil pressure. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
970.
Fatehy M. Abdel‐Haleem Azza Salah Mahmoud S. Rizk Hussein Moustafa Mikhael Bechelany Ahmed Barhoum 《Electroanalysis》2019,31(4):778-789
Thiourea derivative‐based carbon paste electrode (TUD1‐CPE) was constructed as a potentiometric sensor for the determination of salicylate anion in pharmaceutical formulations, Aspocid® and Aspirin®. The optimized CPE contained 45.5 % graphite, 0.5 % reduced graphene oxide (rGO), 46.0 % nitrophenyl octyl ether (NPOE) plasticizer, 5.0 % TUD1 ionophore, and 3.0 % tridodecylmethyl ammonium chloride as additive. The incorporation of NPOE of high dielectric constant, and rGO in electrode caused better performance of the sensor; Nernstian response of 59.0 mV decade?1 in the concentration range of 10?1–10?5 mole L?1, a detection limit of 1×10?5 mole L?1 in a very short response time of 6 seconds. The prepared sensor showed high selectivity against similar anions (i. e. , benzoate, I?, SCN?). Selectivity was confirmed by calculating the formation constant (Kβ) using sandwich membrane method, where Kβ for TUD1‐salicylate is 100.43. Theoretical calculations at DFT‐B3LY/6‐31G** level of theory were performed to find interaction mechanism, Energies of HOMO and LUMO orbitals, non‐linear optical (NLO) properties (the electronic dipole moment (μ), first‐order hyperpolarizability (β), the hyper‐Rayleigh scattering (βHRS) and the depolarization ratio (DR)), and other global properties; these calculations showed lower values of β and DR, higher value of βHRS, and the shortest lengths of the four N?H bonds between TUD1 and salicylate which confirm their strong complexation and salicylate‐selectivity. Also, all the studied anion‐TUD1 exhibited relatively high NLO properties, and these results were considered as a preliminary study for investigating new types of NLO bearing materials. The sensors were applied successfully for the determination of salicylate anion in Aspocid® and Aspirin®. 相似文献