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排序方式: 共有69条查询结果,搜索用时 62 毫秒
41.
42.
P.T. ChurchJ.G. Timourian 《Journal of Differential Equations》2002,181(2):463-510
There is an increasing literature devoted to the study of boundary value problems using singularity theory. The resulting differential operators are typically Fredholm with index 0, defined on infinite-dimensional spaces, and they have often led to folds, cusps, and even higher-order Morin singularities. In this paper we develop some of the local algebras of germs of such differential Fredholm operators, extending the theory of the finite-dimensional case. We apply this work to nonlinear elliptic boundary value problems: in particular, we make further progress on a question proposed and initially studied by Ruf [1999, J. Differential Equations 151, 111-133]. We also make comments on several problems raised by others. 相似文献
43.
A concise and efficient total synthesis of sanggenol F (1) in racemic form has been completed via a sequence of 15 steps with an overall yield of 3.1%, starting from commercially available 2,4,6-trihydroxyacetophenone. Meanwhile, a semisynthesis of sanggenol F racemate has also been achieved in 11.1% overall yield via 7 steps with naturally-occurring morin (2) as the starting material. One step and a stepwise approach were employed to construct the two prenyl side chains at 2- and 6-positions by Claisen rearrangement reaction. 相似文献
44.
采用水相硅烷化方法,将γ-氨基丙基三乙氧基硅烷[H2N(CH2)3Si(OC2H5)3](APES)组装在石英表面,在基底表面修饰上氨基为末端的单层膜,并进一步在这种功能化的单层膜基底上组装金纳米粒子得到金纳米粒子/APES/石英的纳米复合结构。以制备的金纳米粒子自组装膜修饰石英为基底及DL-半胱胺酸为中介,利用桑色素(Morin)和DL-半胱胺酸的化学吸附作用,将桑色素间接组装在金纳米粒子自组装膜修饰石英基底表面,所构建的桑色素修饰金纳米粒子自组装膜对三苯基锡有灵敏的荧光识别作用。文章着重研究了桑色素修饰金纳米粒子自组装膜的制备以及组装条件对其荧光行为的影响,探讨了膜的响应特性及响应机理。 相似文献
45.
In this work, the complex cadmium(II)-morin was synthesized and its interaction with double-stranded salmon sperm DNA was studied by electrochemical methods on glassy carbon electrode (GCE). It was shown that Cd(II)-Morin with high electrochemical activity can intercalate into the double-helix DNA, and the binding stoichiometry and equilibrium dissociation constant according to the Hill model for cooperative binding were calculated to be 1.761 and 2.5 x 10(-5) M, respectively. Using Cd(II)-Morin as a novel hybridization indicator, the hybridization between the probe and its complementary and mismatched sequence was investigated by differential pulse voltammetry (DPV), which was to access the selectivity of the developed electrochemical DNA biosensor. The complementary target ssDNA could be quantified over the range from 2.69 x 10(-8) M to 9.16 x 10(-7) M with a linear correlation of 0.9971 and a detection limit of 9.30 x 10(-9) M. These results demonstrated that the Cd(II)-Morin indicator provides great promise for the rapid and selective measurement of the target DNA. 相似文献
46.
Summary Butyltin and phenyltin species have been separated by ion-exchange chromatography using silica-based and polymer-based columns.
Mobile phases consisted of methanol-water mixtures containing polyfunctional carboxylic acids, which can act as complexing
agents for organotin species. The best results were achieved with a system based on a methanol mobile phase containing malic
and oxalic acids and a polymer-based column, which allowed the separation of tri- and diorganotin compounds and some resolution
between monobutyltin and monophenyltin. 相似文献
47.
Sanchaita Mondal Sujata Das Pradip Kumar Mahapatra Krishna Das Saha 《Molecules (Basel, Switzerland)》2022,27(18)
The special features of cyclodextrins (CDs), hydrophilic outer surfaces and hydrophobic inner surfaces, allow for development of inclusion complexes. The two bioactive strong antioxidant hepatoprotective compounds, Morin and vitamin E, are water insoluble. The present study aimed to prepare Morin-vitamin E-β-cyclodextrin inclusion complex loaded chitosan nanoparticles (M-Vit.E-CD-CS NPs) and to examine their hepatoprotective efficacy against arsenic-induced toxicity in a murine model. The NPs were characterized by FTIR, DLS, NMR, DSC, XRD, AFM, and a TEM study. The NPs were spherical in shape, 178 ± 1.5 nm in size with a polydispersity index (PDI) value of 0.18 and a zeta potential value of −22.4 ± 0.31 mV, with >50% encapsulation and drug loading efficacy. Mice were exposed to arsenic via drinking water, followed by treatment without or with the NPs on every alternate day up to 30 days by oral gavaging. Administration of NPs inhibited the arsenic-induced elevation of liver function markers, inflammatory and proapoptotic factors, reactive oxygen species (ROS) production, alteration in the level of blood parameters and antioxidant factors, and liver damage, which was measured by different biochemical assays, ELISA, Western blot, and histological study. Organ distribution of nanoparticles was measured by HPLC. M-Vit.E-CD-CS NPs showing potent hepatoprotective activity may be therapeutically beneficial. 相似文献
48.
Effects of milling-induced disorder on the lattice parameters and magnetic properties of hematite 总被引:1,自引:0,他引:1
S. J. Stewart R. A. Borzi E. D. Cabanillas G. Punte R. C. Mercader 《Journal of magnetism and magnetic materials》2003,260(3):447-454
A ball-milling treatment in air for 30 min is enough to reduce anhydrous bulk hematite (-Fe2O3) grains to nanometric sizes. For milling times, tm, of 15, 30 min, 1 and 2 h, the crystals suffer an anisotropic lattice dilation, which is more pronounced for the smaller average grain sizes attained. Mössbauer and susceptibility results show that the process alters the effective Morin temperatures, TM. The transition occurs less sharply than for the non-milled material and spreads over a maximum extent of 50 K for tm=30 min. The susceptibility data indicate that the TM for the fraction of material undergoes the transition shifts toward values not lower than 235 K. For tm=10 h the transition is suppressed down to 12 K. Our results do not allow distinguishing bulk from surface regions of the grains. In addition, the disorder brought about by the milling reduces the magnetic response in the weak ferromagnetic state of -Fe2O3. The modification of TM seems to depend mainly on the anisotropic dilation of the unit cell that affects the whole grain and it is related to the nanometric grain sizes achieved. 相似文献
49.
桑色素荧光法测定痕量锗的反应机理研究 总被引:1,自引:0,他引:1
本文对桑色素荧光法测定痕量锗的反应机理进行了较为详细的研究。确定了该反应的络合比,用荧光法,紫外吸收法和红外吸收法确定了反应的位置,从而得到了桑色素荧光法测痕量锗的理论根据。 相似文献
50.
Subarna Mitra Soumen Basu Puspendu Sahu 《Journal of magnetism and magnetic materials》2009,321(18):2925-2931
We report shape- and field-dependent magnetic properties of ellipsoid-, spindle-, flattened- and rhombohedra-shaped α-Fe2O3 samples prepared by solvothermal technique. We observed that a magnetic spin-flip mechanism, mostly known as Morin transition (TM), depends on the shape of α-Fe2O3 as well as on the applied magnetic field. In each of these structures the obtained value of TM was less than its bulk value of 263 K. We observed that TM shifted from highest 251.4 K for ellipsoid to lowest 220.8 K for rhombohedra structure, with intermediate values of TM for the other two structures. However, for rhombohedra structure TM shifted from 220.8 to 177.5 K under the external magnetic field of 100 Oe-30 kOe, respectively. The observed lowering of TM in the structured sample was analyzed in terms of elementary size, shape of the nanocrystallites, lattice parameters and occupancy of Fe+3 ions as well. These parameters were determined from the Rietveld refinement process using MAUD software. 相似文献