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排序方式: 共有159条查询结果,搜索用时 15 毫秒
41.
Zoghi Ali T. Shokouhi Mohammad Naderi Fahimeh Abbasghorbani Maryam Fatehi Azita Pouladi Babak Adhami Mohammad Amin 《Journal of solution chemistry》2022,51(1):84-96
Journal of Solution Chemistry - Hydrogen sulfide and carbonyl sulfide represent undesirable impurities in a variety of industrial gas streams such as natural gas, liquefied natural gas and... 相似文献
42.
Liquid phase microextraction with back extraction (LPME-BE) combined with liquid chromatography-ultra violet (LC-UV) was applied for the extraction and determination of methadone in biological fluids. At the optimized conditions, an enrichment factor of 386 and detection limit (LOD) of 0.2 μg L?1 were obtained. The calibration curve was linear (r 2 = 0.989) in the concentration range of 0.6–1,000 μg L?1. Within-day relative standard deviation RSD (S/N = 3) and between-day RSD were 2.7 and 5.9%, respectively. The feasibility of the proposed method was evaluated by extraction and determination of methadone in plasma and urine samples and satisfactory results were obtained. 相似文献
43.
Ahmad Shaabani Mozhdeh Seyyedhamzeh Ali Maleki Maryam Behnam Fahimeh Rezazadeh 《Tetrahedron letters》2009,50(24):2911-4167
A one-pot four-component reaction of an aliphatic or aromatic amine, diketene, an aromatic aldehyde and 1,3-diphenyl-1H-pyrazol-5-amine in the presence of p-toluenesulfonic acid as a catalyst has been developed. In this reaction, a new class of fully substituted pyrazolo[3,4-b]pyridine-5-carboxamide derivatives is produced under mild reaction conditions and in good yields at ambient temperature. 相似文献
44.
Dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) with simultaneous derivatization followed by high-performance liquid chromatography-diode array detection (HPLC-DAD) was applied for preconcentration and determination of primary and secondary aliphatic amines in environmental water samples. A ternary mixture consisting of a disperser, an extractant and a derivatization reagent was used for the simultaneous derivatization and extraction of aliphatic amines in different water samples. The effects of various experimental parameters on derivatization and extraction efficiency were studied simultaneously using experimental design. A Plackett-Burman design was performed for screening of variables in order to determine the significant variables affecting the extraction efficiency. Then, the significant factors were optimized by using a Box-Behnken design (BBD) and the response surface equations were derived. Under optimal conditions, the preconcentration factors were between 210 and 290. The limit of detections (LODs) ranged from 0.005 to 0.02 μg/L and dynamic linear ranges (DLRs) of 0.05-500 and 0.1-500 μg/L were obtained for most of analytes. The performance of the method was evaluated for extraction and determination of primary and secondary aliphatic amines in environmental water samples in micrograms per liter and satisfactory results were obtained (RSDs <12.5%). 相似文献
45.
Fahimeh Khosh-Ahang 《Archiv der Mathematik》2009,93(4):315-317
In this note, we provide a short argument which corrects flaws in the mentioned article. 相似文献
46.
A solid uncharged complex produced from 2‐aminocyclopentene‐1‐dithiocarboxylic acid (synthetic reagent) on naphthalene provides a very sensitive, selective and economical method for the preconcentration and determination of trace amounts of copper in drug and alloy samples. The 2‐aminocyclopentene‐1‐dithiocarboxylate of copper is retained quantitatively on microcrystalline naphthalene in the pH range 2.8–3.3. After filtration the solid mass consisting of copper complex‐naphthalene is dissolved with 4 mL of dimethylformamide (DMF). The absorbance is measured at 462 nm with a spectrophotometer against the reagent blank and molar absorptivity found to be 2.8 × 105 liter mol?1 cm?1. Beer's law is obeyed over the concentration range of 0.1–16.0 μg of copper in 4 mL of the dimethylformamide solution. Detection limit is 3 ng mL?1 [signal to noise ratio = 2]. Ten replicate determinations on a sample containing 1 μg of copper gave a relative standard deviation of 0.76%. The interference of a large number of anions and cations have been studied and the optimized conditions developed were utilized for determination of copper in various real samples. 相似文献
47.
Fahimeh Khosh-Ahang 《Archiv der Mathematik》2008,90(1):18-23
In this paper, we compare Krull dimension, Gorenstein injective dimension and injective dimension of a module in several cases.
In fact, we establish some generalizations of the Bass formula. To this end, we generalize the Grothendieck non-vanishing
theorem to a class of modules larger than finitely generated modules.
Received: 21 May 2007 相似文献
48.
49.
Hamid Reza Shaterian Asghar Hosseinian Majid Ghashang Fahimeh Khorami 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2490-2501
Carbonyl compounds have been successfully converted into their corresponding dithiolanes and dithianes derivatives with 1,2-ethanedithiol and 1,3-propanedithiol in excellent yield at room temperature and short reaction times using a catalytic amount of magnesium hydrogensulfate. The synthetic simple procedures reported in this paper constitute an exceptionally mild procedure for carbonyl protection in ambient conditions. 相似文献
50.
Amine‐Promoted One‐Pot,Multicomponent Route to Spiro‐Fused‐Pyran Derivatives in Aqueous Media 下载免费PDF全文
The primary amine‐promoted synthesis of spiro‐fused‐pyran derivatives via the three‐component reaction of ninhydrin, malononitrile, and cyclic 1,3‐diketo compounds is described. This new methodology affords the title compounds in high yields and short time, and with easy workup without chromatographic purification steps or extraction. All structures were confirmed by IR, 1H‐ and 13C‐NMR spectroscopy, and mass spectroscopy. A plausible mechanism for this type of reaction is proposed (Scheme 2). 相似文献