首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
A new HPLC method was developed for the determination of amlodipine and perindopril in their binary mixture as a part of a routine control of combined formulations. For the first time an HPLC method was used for an in vitro dissolution study of tablets containing the above drugs. The presented method was validated to meet official requirements and this validation included specificity, stability, linearity, precision and accuracy. Chromatography was carried out using a LiChrospher RP-18 column, a mixture containing acetonitrile and phosphate buffer of pH 3.0 (50:50, v/v) as mobile phase and UV detection at 225 nm. The dissolution test was performed using 900 mL of phosphate buffer at pH 5.5 containing 1% cetylpyridini chloride (CPC) at 37°C and 75 rpm, using the paddle method. Robustness procedure was done according to the plan defined by the Plackett-Burman design. The effects of acetonitrile content, pH of the buffer and flow rate of the mobile phase, column temperature, pH and CPC content in the dissolution medium as well as rotation speed of the paddle were considered. After that, both graphical and statistical methods were used for identification of significant and non-significant effects.   相似文献   

3.
In this review an exhaustive crystallochemical analysis of copper(I) π-complexes with allyl derivatives of heterocyclic compounds has been performed. Structural genesis of inorganic constituents starting from the simplest units to the most complicated aggregates was considered taking into account the specific role of Cu-(C=C) interaction, the construction of the organic ligands, the basicity and nucleophilic activity of their heteroatoms, as well as olefin Cu(I) π-complex preparation route.   相似文献   

4.
The thermal decomposition of five double-base propellants modified with RDX was studied by dynamic pressure thermal analysis to determine the effect of RDX content (20–60 wt.%) on performance. All have good stability. Both stability and activation energy increase as RDX increases from 20% to 50% then decrease; 50% RDX performs best. The decomposition mechanism is affected by RDX content and temperature. Increasing temperature induces autocatalysis and accelerates decomposition.   相似文献   

5.
The optimal parameters for ultrasonic treatment (frequency 200–300 kHz, intensity 2–4 W cm?2) were obtained to intensify Pb(II) and Cd(II) sorption concentration by carbon sorbent from apricot pit. The combined action of ultrasonic frequency of 18 kHz and 1 MHz on concentrate slurry increases its sedimentation stability from 3 to 180 minutes and decreases Sr value up to 7% at Pb(II), Cd(II) hybrid sorption atomic absorption determination in natural waters, brines, common salt.   相似文献   

6.
The water-soluble sunscreen 2-phenylbenzimidazole-5-sulfonic acid (PBS) was quantified in a sun-care product and water samples by thin layer chromatography followed by densitometric scanning in fluorescence mode (cut-off filter 370 nm, wavelength of excitation — 300 nm). Normal phase TLC was performed on silica gel 60 as stationary phase. Mobile phase used was ethyl acetate-ethanol-water 70:35:30 (v/v/v). The limit of detection (LOD) was 0.0004 μg spot-1, and the limit of quantification (LOQ) was — 0.001 μg spot?1 without any sample pre-concentration.   相似文献   

7.
A novel QSAR approach based on correlation weighting and alignment over a hypermolecule that mimics the investigated correlational space was performed on a set of 40 caffeines downloaded from the PubChem database. The best models describing log P and LD50 values of this set of caffeine derivatives were validated against the external test set and in a new predictive model by using clusters of similarity.   相似文献   

8.
Protoescigenin, the main aglycone of horse chestnut saponin mixture known as escin, was selected as substrate for exploratory chemistry towards selective protection, followed by propargyl ether formation and subsequent condensation with azido-monosaccharides, to obtain novel triazole linked conjugates of the triterpene.   相似文献   

9.
Amination by organic azides has been carried out to provide aminobarbiturates by fusion of a triazole ring to the 5,6-positions of barbituric acid followed by cleavage and thermal elimination of nitrogen, whereas aza-Wittig reaction gave phosphoranylidene barbituric acid salts.   相似文献   

10.
The synthesis of 3-deoxyoripavine (7) was realized as a novel and promising intermediate towards the synthesis of the important class of dopaminergic and/or serotonergic 10-deoxyaporphines and the special pharmacological tool µ opioid antagonist cyprodime. Generally, the preparation of these valuable biologically active compounds was achieved in remarkable yields.   相似文献   

11.
The present paper deals with chemical and physicochemical characterization of seven glass fragments of medieval glass bracelets from South-East Bulgaria. Samples were investigated by Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and differential thermal analysis (DTA). Gravimetric chemical analysis was used for silica assessment. Flame photometry was applied to determine sodium and potassium content while aluminium, calcium and magnesium were determined by flame atomic absorption spectrometry after dissolution using a mixture of acids. All investigated artefacts are soda-lime-silica glasses and when produced two different recipe norms were used. Important technological parameters of glass manufacturing were determined and discussed. This investigation throws light on the technological development and production of glass during medieval times.   相似文献   

12.
The RS-stereoisomeric group $\mathbf{T}_{d\widetilde{\sigma }\widehat{I}}$ is examined to characterize quadruplets of RS-stereoisomers based on a tetrahedral skeleton and found to be isomorphic to the point group $\mathbf{O}_{h}$ of order 48. The non-redundant set of subgroups (SSG) of $\mathbf{T}_{d\widetilde{\sigma }\widehat{I}}$ is obtained by referring to the non-redundant SSG of $\mathbf{O}_{h}$ . The coset representation for characterizing the orbit of the four positions of the tetrahedral skeleton is clarified to be $\mathbf{T}_{d\widetilde{\sigma }\widehat{I}}(/\mathbf{C}_{3v\widetilde{\sigma }\widehat{I}})$ , which is closely related to the $\mathbf{O}_{h}(/\mathbf{D}_{3d})$ . According to the unit-subduced-cycle-index (USCI) approach (Fujita in Symmetry and combinatorial enumeration in chemistry. Springer, Berlin, 1991), the subdution of $\mathbf{T}_{d\widetilde{\sigma }\widehat{I}}(/\mathbf{C}_{3v\widetilde{\sigma }\widehat{I}})$ is examined so as to generate unit subduced cycle indices with chirality fittingness (USCI-CFs). The fixed-point matrix method of the USCI approach is applied to the USCI-CFs. Thereby, the numbers of quadruplets are calculated in an itemized fashion with respect to the subgroups of $\mathbf{T}_{d\widetilde{\sigma }\widehat{I}}$ . After the subgroups of $\mathbf{T}_{d\widetilde{\sigma }\widehat{I}}$ are categorized into types I–V, type-itemized enumeration of quadruplets is conducted to illustrate the versatility of the stereoisogram approach.  相似文献   

13.
After the RS-stereoisomeric group \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}\) of order 16 has been defined by starting point group \(\mathbf{D}_{2d}\) of order 8, the isomorphism between \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}\) and the point group \(\mathbf{D}_{4h}\) of order 16 is thoroughly discussed. The non-redundant set of subgroups (SSG) of \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}\) is obtained by referring to the non-redundant set of subgroups of \(\mathbf{D}_{4h}\) . The coset representation for characterizing the orbit of the four positions of an allene skeleton is clarified to be \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}(/\mathbf{C}_{s\widetilde{\sigma }\widehat{I}})\) , which is closely related to the \(\mathbf{D}_{4h}(/\mathbf{C}_{2v}^{\prime \prime \prime })\) . According to the unit-subduced-cycle-index (USCI) approach (Fujita, Symmetry and combinatorial enumeration of chemistry. Springer, Berlin 1991), the subduction of \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}(/\mathbf{C}_{s\widetilde{\sigma }\widehat{I}})\) is examined so as to generate unit subduced cycle indices with chirality fittingness (USCI-CFs). Then, the fixed-point matrix method of the USCI approach is applied to the USCI-CFs. Thereby, the numbers of quadruplets are calculated in an itemized fashion with respect to the subgroups of \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}\) . After the subgroups of \(\mathbf{D}_{2d\widetilde{\sigma }\widehat{I}}\) are categorized into types I–V, type-itemized enumeration of quadruplets is conducted to illustrate the versatility of the stereoisogram approach.  相似文献   

14.
Pure Polyaniline (EB) and Polyaniline doped with different protonic acids (ESs) were chemically synthesized using ammonium peroxydisulphate (APS) as an oxidant. Junctions have been prepared by evaporating chalcogenide materials (ZnSe, CdSe) on conducting polyaniline (EB & ESs) pellets using a vacuum evaporation technique. I–V characteristics of junctions have been studied at room temperature using the Keithley electrometer 6517A. I–V measurements show the rectification effect. A junction of ES[PO4 3?] may be preferred over the other junctions due to its low ideality factor and maximum rectification ratio.   相似文献   

15.
Enantioselective organocatalytic Michael additions affords useful building blocks for many biologically and medicinally relevant compounds. Ionically-tagged diphenylprolinol silyl ether efficiently catalyzes several Michael additions of aldehydes to nitroalkenes in ionic liquids. The Michael additions work well in ionic liquids; yields up to 95% and enantioselectivities up to 95% ee were achieved. Furthermore, in some cases, the catalytic system was reusable.   相似文献   

16.
A series of new ruthenium(II) complexes were synthesized with Schiff bases derived from salicylaldehyde / o-hydroxyacetophenone/ o-vanillin / 2-hydroxy-1-naphthaldehyde with thiosemicarbazide and acetyl furan. They are characterized by elemental analysis, IR, electronic, 1H NMR, 13C NMR and mass spectral studies. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). Four of these complexes were tested for its binding with CT-DNA using absorption spectroscopic studies and two of these complexes exhibit efficient DNA cleavage activity.   相似文献   

17.
New potentially biologically active compounds derived from 2-mercapto-benzoxazole were synthesized and coupled on polymeric support of poly (maleic anhydride-alt-vinyl acetate) for the preparation of polymer-drug conjugates with controlled drug release. All compounds were characterized by elemental and spectroscopy (FT-IR, 1H-NMR) analysis. The toxicological tests recommend the products for further laboratory screening.   相似文献   

18.
Nickel catalysts supported on Na-mordenite were used for paraffin LTP56-H hydroconversion into liquid material as a possible component for engine fuels. The effects of none-catalytic thermal treatment and catalytic conditions-zeolite type and reaction conditions (solvent) on the process of liquefaction of LTP56-H paraffin and physicochemical properties of catalysts were studied. The physicochemical properties of catalytic systems were investigated using XRD, TPR, TPD-NH3 and SEM-EDS methods.   相似文献   

19.
This article considers the possibility of applying the positron annihilation spectroscopy method for investigating the pore space of rocks from oil-gas and methane-coal deposits. The diagnostics of the structure was performed using the method of spectrometry of angular correlation of annihilation rays (ACAR). Using the samples of porous silicon, the authors have shown the applicability of the ACAR method for determination of the average dimensions of spherical and cylindrical nanosized objects and their concentration   相似文献   

20.
The corrosion properties of the passive layers formed on iron-nickel-chromium electrodeposits of Fe29Ni51Cr20 were investigated in 0.3 M borate solution at a‘ pH of 8.4. On the basis of measurements by cyclic voltammetry, chronopotentiometry and electrochemical impedance spectroscopy, a low passive dissolution/corrosion rate was identified for the electrodeposited Fe-Ni-Cr alloys due to the nature of the established corrosion layer. The stability of this passive layer was further enhanced after corrosion under oxidizing conditions. Mössbauer spectroscopic measurements confirmed the existence of a thin passive layer on the amorphous electrodeposits.   相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号