Compound determined methods
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The structure of the new acid and data of potentiometric titration were analyzed in detail before calculating and assigning the pKa values to suitable functional groups. These results will be applied to our further studies of this compound.
7p vimaryamnawaz 04-08-2022 7 1 Download
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Develop a rapid and simple method for analysis of multi-residue pesticides, including organophosphate, organochlorine, carbamate, and pyrethroid compounds in soil, with sample preparation based on QuEChERS technique and determination by GC-MS.
26p capheviahe26 25-01-2021 28 3 Download
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Building approximation formulas using equivalentinclusion method to determine the effective values of the conductivity, the elastic modulus of compound-inclusion composite materials and applying numerical methods using finite elements (FE) calculated for some specific material models.
27p capheviahe26 25-01-2021 14 3 Download
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The phytochemical analysis and antibacterial and antioxidant activity of Ardisia silvestris extracts were carried out. The bioactive compounds of Ardisia silvestris leaves were extracted with petroleum ether, ethyl acetate, ethanol and water by immersion and microwave method. The DPPH method was used to determine the antioxidant activity of Ardisia silvestris extracts.
8p larachdumlanat129 19-01-2021 17 3 Download
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From the methanol extract of dried powders of Hedyotis diffusa Willd. (Rubiaceae) plant growing in Tuyen Quang Province, three compounds were isolated and identified: B-sitosterol, daucosterol and ursolic acid. Their structures were confirmed by various spectral methods (IR, NMR, MS, 1H-NMR, 13C-NMR, etc.) and by comparison with those of references.
5p larachdumlanat127 20-12-2020 28 2 Download
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Study on the chemical constituents of methanol extract from leaves of Moringa oleifera Lam. (Moringaceae) has resulted in the isolation of four compounds: Vitexin, isoquercitrin, tricosanol and tetradecanoic acid. Their structures were determined by spectroscopic methods.
5p tamynhan9 02-12-2020 25 2 Download
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In this work, we investigated the adsorption mechanism of acetone and toluene on the surface of silicene by the quantum simulation method. The images of the potential energy surfaces for different positions of the adsorbate on the silicene surface were explored by Computational DFTbased Nanoscope tool for determination of the most stable configurations and diffusion possibilities.
8p tamynhan6 14-09-2020 21 2 Download
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An analytical procedure for the analysis of carotenoids in marine sediments rich in organic matter has been developed. Analysis of these compounds is difficult; the application of methods used by other authors required optimization for the samples studied here.
14p tocectocec 25-05-2020 23 1 Download
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The trap was then heated to release volatile compounds including ethylmethylmercury into a GC-AFS for separation and detection. The instrumental detection limit was 4.8 pg Hg/L. The method can therefore be applied for the determination of methylmercury in water samples at ultra – trace.
8p elandorr 03-12-2019 20 0 Download
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To extract, isolate, determine the structure of compounds from Huperzia serrata (Thunb.) Trevis. Subjects and methods: The samples were collected in Tamdao National Park. The structure of substances was determined by spectral methods. Results and conclusions: 2 compounds of terpenoid group were isolated, namely: 3β, 21β, 29-trihydroxyserrat-14-en-24-oic acid-3β-yl- (7’-hydroxycinnamate); 16-oxo-3α-hydroxyserrat-14-en-21β-ol, the substances were confirmed by the structure of NMR, MS, HMBC, HSQC.
5p chauchaungayxua1 02-12-2019 9 0 Download
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Research objectives of the thesis: Study the process of simultaneous determination and evaluation of the method of analyzing 7 chlorobenzene, including 1,2- 4 dichlorobenzene (1,2-DCB); 1,3-dichlorobenzene (1,3-DCB); 1,2,4- trichlorobenzene (1,2,4-TCB); 1,2,3,4-tetrachlorbenzene (1,2,3,4- TeCB), 1,2,4,5-tetraclobenzene (1,2,4,5-TeCB); pentaclobenzene (PeCB) and hexaclobenzene (HCB) in trace and superficial content in flue gas samples and industrial waste (fly ash, bottom ash, input materials).
26p xacxuoc4321 08-07-2019 49 9 Download
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Two limonoids limonin and limonexic acid have been isolated from the dichloromethane extract of leaves of Tetradium trichotomum, besides three indolopyridoquinazoline alkaloids, rutaecarpine, evodiamine, N13 -methyl rutaecarpine and -sitosterol. The structures of these compounds were determined by spectroscopic methods.
4p uocvong05 09-10-2015 33 2 Download
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Starting from 3-hydroxy-lup-20(29)-en-23,28-dioic acid, which is isolated with high yield from the plant Schefflera octophylla (Lour.) Harms (Araliaceae), a series of amide esters and amide acids with amino acids have been synthesized. All the synthesized compounds are new. Their structures were determined by IR, MS and NMR spectroscopic methods.
5p uocvong04 24-09-2015 52 2 Download
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The different components of the rihzomes of Alpinia laosensis Gagnep was extracted by petroleum ether, ethyl acetate and methanol. From residue of the extract of petroleum ether, 3- (p-acetylphenyl)-3-metylcacboxyl-1-propen was isolated fraction distillation. The structure of the compound determined methods.
4p uocvong04 24-09-2015 42 3 Download
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Starting from 3-hydroxy-lup-20(29)-ene-23,28-dioic acid, isolated with high yield from the plant Schefflera octophylla (Lour.) Harms (Araliaceae), a series of amide esters and amide acids have been synthetized. All the synthetized compounds are new. Their structures were determined by the IR, MS and NMR spectroscopic method.
5p uocvong04 24-09-2015 52 3 Download
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Two derivatives of 2-thioxoquinazolin-4(3H)-one including compounds 3 and 5 were synthesized by cyclization reaction of anthranilic acid with ethyl isothiocyanate and phenyl isothiocyanate, respectively. Eight novel derivatives of 2-thioxoquinazolin-4(3H)-one including compounds (7a-h) were synthesized by cyclization reaction of derivatives of anthranilic acid with aromatic amines and carbon disulfide in potassium hydroxide/methanol. The obtained compounds were structurally determined by IR, MS, 1 H NMR and 13 C NMR analysis method.
6p uocvong03 24-09-2015 44 3 Download
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Lead dioxide has been electrodeposited onto 304 stainless steel in three-solution with different compound and pH by ganvanostatic method. The X-Ray diffraction and scanning electron microscopy (SEM) techniques have been used to determine morphologic structure of lead dioxide. The obtained results have shown that lead dioxide has two forms crystal and, the faradic yield of electrodeposition process lead dioxide in the acid and alkali solution is more than in the neutral solution.
6p uocvong01 24-09-2015 42 4 Download
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Advanced glycation end-products (AGEs) of DNA are formed spontane-ously by the reaction of carbonyl compounds such as sugars, methylglyoxal or dihydroxyacetonein vitro andin vivo. Little is known, however, about the biological consequences of DNA AGEs. In this study, a method was developed to determine the parameters that promote DNA glycation in cultured cells.
12p media19 05-03-2013 26 3 Download
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Since the subject of nuclear magnetic resonance (NMR) was awarded its first Nobel Prize in 1952 due to its successful detection by Bloch and Purcell in 1945, the technology and its applications have developed tremendously. The first two decades were focused on technical developments of instrumentation and methodologies to apply to the structure determination of compounds. During the late 1970s, several research groups developed modifications of NMR probes to convert them to an online mode for the analysis of sample mixtures....
232p bachduong1311 12-12-2012 87 6 Download
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Introduction: Determination of methemoglobin (Met-Hb) in blood is important for the diagnosis of poisoning by oxidants, such as nitrite, nitrate, chlorate, chlorite, alkyl nitrites, nitroglycerin, aniline and other compounds. In 1938, Evelyn and Malloy [1] had devised a photoelectric method for determination of Met-Hb in blood. Minor modifications of this method were made by several researchers to increase sensitivity [2–4]. These methods are based on a phenomenon that the absorbance maximum of weakly acidic Met-Hb at 630 nm disappears by addition of cyanide.
17p bigbaby87 01-09-2010 159 14 Download