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951.
Munawar Ali Munawar Muhammad Azad Hamid Latif Siddiqui Faiz‐Ul‐Hassan Nasim 《中国化学会会志》2008,55(2):394-400
The quinolinylpyrimidine derivatives were prepared by the condensation of quinolinyl chalcones with urea (or thiourea) under basic conditions by using both conventional and microwave heating. Their IR, 1H NMR, 13C NMR, mass spectra and CHN analyses confirmed the prepared compounds. The newly prepared quinolinylpyrimidine derivatives were screened for antimicrobial activities against the bacterial strains viz. S. aureus, Shigella, Salmonela, P. aeroginosa, B. Subtilus and E. coli and found considerably active against S. aureus, P. aeroginosa and E. coli. 相似文献
952.
953.
Conductivity detection, which is universal in capillary electrophoresis (CE), has received considerable attention, since the introduction of the axial capacitively coupled contactless detector C4D in 1998. This detector is made of two electrodes which are placed cylindrically around the CE capillary and connected to the AC oscillator. The distance between the electrodes is the detection gap. In this review, applications of CE and MCE with C4D in pharmaceutical and biological analysis are presented. 相似文献
954.
Schneider BB Baranov VI Javaheri H Covey TR 《Journal of the American Society for Mass Spectrometry》2003,14(11):1236-1246
An atmosphere to vacuum interface was designed to exploit the different mobility and momentum characteristics of ions, and charged and neutral particles in electrospray ionization-mass spectrometry. The purpose of this device is to transmit with high efficiency the ions created at atmospheric pressure into the mass analyzer and to deflect the large charged and neutral particles prior to entrance into the vacuum system, thereby maintaining system cleanliness and stability. This interface is particularly suitable for low flow rate electrospray ionization-mass spectrometry where the close proximity of the electrospray emitters to the vacuum entrance, and near total consumption of the entire spray, leads to the production of large quantities of non-desolvated droplets and large charged and neutral particles. The improvement involves the application of potential gradients to a particle discriminator space located between the gas restricting ion entrance orifice of the mass spectrometer and the exit of a heated laminar flow chamber to divert large particles from the gas conductance limiting orifice. A counter-current flow of drying gas is used to deflect neutral particles and solvent vapor. Two stages of desolvation are achieved with the combined effects of the curtain gas and heated laminar flow chamber. This enhances the efficiency of desolvation and ion production, and stabilizes the resulting ion current under a wide variety of solvent compositions. In addition, this system eliminates the problems associated with the boiling of solution in nanospray tips when operated in close proximity to a heated mass spectrometer inlet. The particle discriminator interface gives approximately a 2-fold improvement in ion count rates, and a 3-fold improvement in stability (as measured by the signal relative standard deviation). 相似文献
955.
Summary Lanthanum nitrate is recommended as a new external absorbent eliminating fluorine interferences at room temperature in the analysis of various fluorinated materials by the Korshun-Klimova method yielding accurate carbon and hydrogen values.
Lanthannitrat als äueres Absorptionsmittel bei der C-H-Mikrobestimmung in Fluorund Perfluorverbindungen
Zusammenfassung Lanthannitrat wird als äußeres Absorptionsmittel für Fluor bei Raumtemperatur bei der C-H-Bestimmung nach Korshun-Klimova empfohlen.相似文献
956.
The construction and electrochemical response characteristics of poly (vinyl chloride) and poly (vinyl chloride) carboxylate membrane sensors for the determination of cyclophosphamide and ifosphamide are described. Based on the formation of an ion-pair complex between the drug cation and sodium tetraphenylborate, two poly (vinyl chloride) sensors, namely a cyclophosphamide membrane sensor and ifosphamide membrane sensor were fabricated. They show a linear response for both drugs over the concentration range 10−2–10−4 M with cationic slopes of 56 and 54.6 mV per concentration decade, for sensor 1 and sensor 2, respectively. Based on the interaction between the drug solution and the dissociated COOH groups in the poly (vinyl chloride) carboxylate, sensor 3 was fabricated. It shows a linear response for both drugs over the concentration range 10−3–10−5 M with a cationic slope of 49.7 mV per concentration decade. The direct potentiometric determination of cyclophosphamide and ifosphamide in their pharmaceutical preparations using the proposed sensors gave average recoveries of 101.3±0.6, 100.8±10.7 and 102.0±11.0% for the sensors 1, 2 and 3, respectively, which compares reasonably well with the data obtained using the British Pharmacopoeial method (1993). Sensors 1 and 2 were also used to follow up the stability of the drugs studied in the presence of their degradates. These degradation products have no diverse effect on the responses of sensors 1 and 2. 相似文献
957.
Pardi LA Hassan AK Hulsbergen FB Reedijk J Spek AL Brunel LC 《Inorganic chemistry》2000,39(2):159-164
The synthesis, X-ray structure, and EPR measurements of the integer-spin linear-chain antiferromagnet [Ni(ox)(dmiz)2] (where ox = C2O4(2-) and dmiz = 1,2-dimethylimidazole) are presented. The sign and size of the single-ion zero field splitting (Zfs) of the divalent Ni have been determined by high field/high-frequency EPR spectroscopy. The spectra of powder samples of the derivatives [NixZn1-x(C2O4)(dmiz)2] for x = 0.09 and 0.07, at frequencies ranging from 110 to 440 GHz allowed the accurate determination of the zfs parameters D and E, with D = 1.875(4) cm(-1) and E = 0.38 cm(-1). The X-ray structure has been determined from measurements on a single crystal with x = 0.07. Structural parameters are as follows: a = 14.5252(7) A, b = 12.1916(8) A, c = 8.6850(8) A,beta = 97.460(6)degrees in space group C2/c. The zigzag chain contains octahedrally coordinated metal ions with two cis-oriented N-coordinated dmiz ligands and two cis-oriented, tetradentate bridging oxalato(2-) ligands, together resulting in a MN2O4 donor set. The structure was refined to a conventional R value of 0.073 for 1,051 observed reflections. Zn-O distances are 2.167(5) A and Zn-N = 2.098 A. Coordination angles vary for cis angles from 78.4 to 100.7 degrees, with trans angles varying from 163.9 degrees to 165.5 degrees. 相似文献
958.
In this work, oximes are converted to their corresponding carbonyl compounds in good yields using N‐bromo‐N‐phenyl‐para‐toluenesulfonamide, under microwave irradiation. The simple work‐up procedure minimizes loss of product. 相似文献
959.
Line Lucry Ferdinand Enoma Franois Estour Sabine Mnager Olivier Lafont Hassan Oulyadi 《Journal of heterocyclic chemistry》2002,39(4):663-670
A series of 46 3‐phenyloctahydropyrimido[1,2‐a]‐s–triazine derivatives were synthesized. This synthesis was performed via iminodimethylation of dialkylated 2‐aminopyrimidinedione synthons by substituted primary arylamines. In vitro pharmacological evaluation of these compounds is reported. One of them exhibited antifungal activity against Microsporum canis (10?65010?5 mol/L), and another showed affinity for serotoninergic 5‐HT1A and 5‐HT2b receptors (10?85010?7 mol/L). 相似文献
960.
Inas El Hassan Robert Lauricella Béatrice. Tuccio 《Central European Journal of Chemistry》2006,4(2):338-350
The syntheses of seven N-aryl-C,C-dialkoxycarbonylnitrones 1–7, six of which were original, were achieved from the appropriate aryl-nitroso compounds. These ketonitrones were found to
trap efficiently carbon-centred free radicals in aqueous media, yielding stable aminoxyl radicals whose EPR spectra lasted
several days. The two penta-deuterated compounds 6 and 7 were also found to be efficient at trapping methoxyl radical. Their various spin adducts showed simple three line signals,
very sensitive to the polarity of the environment. This study represents the very first use of linear ketonitrones as spin
traps. 相似文献