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131.
132.
M. E. Kassem E. F. El-Wahidy S. H. Kandil M. A. El-Gamal 《Journal of Thermal Analysis and Calorimetry》1984,29(2):325-331
Thermal analysis, DTA, TG, TMA and DSC were performed on LiKSO4 in the temperature range 300 to 800 K, using a Heraeus TA 500 thermal analyser. The thermal expansion coefficients measured along the three fundamental crystallogrpahic axes, together with the specific heatC p, show anomalous behaviour around the phase transition temperature of these crystals atT c=705 K. Anisotropy in the thermal expansion coefficient as well as endothermic peaks aroundT c were also observed, while no loss of weight was detected. The temperature-dependence of the thermal conductivity of LiKSO4 crystals has been estimated, using the temperature-variation of the thermal diffusivity. 相似文献
133.
Pashynska V Vermeylen R Vas G Maenhaut W Claeys M 《Journal of mass spectrometry : JMS》2002,37(12):1249-1257
We developed and validated a gas chromatographic/ion trap mass spectrometric method for the determination of levoglucosan and the related monosaccharide anhydrides, mannosan, galactosan and 1,6-anhydro-beta-D-glucofuranose in urban atmospheric aerosols collected on quartz fiber filters. The method is based on extraction with dichloromethane-methanol (80 : 20, v/v), trimethylsilylation, multiple reaction monitoring in the tandem mass spectrometric mode using the ion at m/z 217, and the use of an internal standard calibration procedure with the structurally related compound methyl beta-L-arabinopyranoside. In addition, the method allows the quantification of other saccharidic compounds, arabitol, mannitol, glucose, fructose, inositol and sucrose, which were found to be important in summer aerosols. The recovery of levoglucosan was estimated by spiking blank filters and was better than 90%. The precision evaluated by analyzing parts of the same filters was about 2% for the monosaccharide anhydrides and 7% for the other saccharidic compounds in the case of a winter aerosol sample, and the corresponding values for a summer aerosol sample were 5% and 8%. The method was applied to urban PM(10) (particulate matter of <10 microm aerodynamic diameter) aerosols collected at Ghent, Belgium, during a 2000-2001 winter and a 2001 summer episode and revealed interesting seasonal variations. While monosaccharide anhydrides were relatively more important during the winter season owing to wood burning, the other saccharidic compounds were more prevalent during the summer season, with some of them, if not all, originating from the vegetation. 相似文献
134.
Csaba Várhelyi Magda Somay Antal Koch Ernő Grünwald 《Monatshefte für Chemie / Chemical Monthly》1978,109(6):1311-1320
Some new ligand exchange reactions of [Co(diph·H)2Cl(H2O)] and [Co(diph·H)2(SO3)(H2O)]– complexes with N3
–, S2O3
2– and with aromatic and heterocyclic amines were carried out. A series of derivatives of the types [Co(diph·H)2(SO3)X]
n–
(X=N3
–, S2O3
2– oramine) and [Co(diph·H)2(S2O3)2]3– were described and characterized. Some structural problems are resolved and discussed on the basis of UV and IR spectral data. 相似文献
135.
Yolanda Pérez Isabel del Hierro Isabel Sierra Magda Monari Antonio Otero 《Journal of organometallic chemistry》2004,689(22):3492-3500
A variety of monocyclopentadienyl alkoxo titanium dichloride and bisalkoxo titanium dichloride complexes have been prepared and characterized by spectroscopic techniques. The titanium derivatives containing both cyclopentadienyl and various alkoxo ligands [Ti(η5-C5H5)(OR)Cl2] (1-5) have been synthesized from the reaction of [Ti(η5-C5H5)Cl3] with 1 equivalent of the corresponding alcohol in THF in the presence of triethylamine (ROH = Adamantanol, 1R,2S,5R-(−)-menthol, 1S-endo-(−)-borneol, cis-1,3-(−)-benzylideneglycerol, 1,2:3,4-di-O-isopropylidene-α-d-galactopyranose). The bisalkoxo titanium dichloride derivatives [TiCl2(OR)2] (6-10) have been prepared by a redistribution reaction between Ti(OR)4 and TiCl4 compounds 6-8 (OR = Adamantanoxy, (1R,2S,5R)-(−)menthoxy, (1S-endo)-(−)-borneoxy) and by reaction of [Ti(OR)2(OPri)2]2 with CH3COCl compounds 9 and 10 (OR = 1,2:3,4-di-O-isopropylidene-α-d-galactopyranoxy, and 1,2:5,6-di-O-isopropylidene-α-d-glucofuranoxy). The molecular structures of 2 and 3 have been determined by single crystal X-ray diffraction studies. 相似文献
136.
Abdou O. Abdehamid Cyril PÁrkÁnyi Ahmad S. Shawali Magda A. Abdalla 《Journal of heterocyclic chemistry》1984,21(4):1049-1054
Aminocyanopyrazole derivatives and pyrazolo[2,3-a]quinazolones were obtained in good yields from hydrazidoyl halides and malononitrile. Pyrazolo[3,4-d]pyridazine and pyridazo[4′,5′: 1,2]pyrazolo[1,5-a]quinazoline derivatives were synthesized in quantitative yields by reaction of hydrazine hydrate with 2 and 16 , respectively. A novel ring system, a 3-substituted tetrahydro derivative of 7-oxo-6H,8H-pyridazo[3′,4′,5′-c'd']-pyrazolo[3,4-d]pyrimidine was prepared by reaction of 6 with dimethyl carbonate. Pyrazolo[3,4-d]pyrimidine-4,6-dithiones were obtained in good yields by reaction of 2 with carbon disulfide. The structures of the products were assigned and confirmed on the basis of their elemental analyses, spectral data, and alternate synthesis wherever possible. The structures of the parent fused heterocyclic systems discussed in this work are summarized in Scheme 1 . 相似文献
137.
Kamal A. Idriss Magda S. Saleh Hassan Sedaira M. M. Seleim Elham Y. Hashem 《Monatshefte für Chemie / Chemical Monthly》1991,122(6-7):507-520
Summary The solution equilibria of 2-hydroxynicotinic acid (hyna) complexes with mercury(II) have been studied spectrophotometrically in 50% (v/v) ethanol at 20°C and an ionic strength of 0.1mol dm–3 (NaClO4). Three mercuric complexes are formed in solution in dependence on the acidity of the medium. The basic characteristics of the different complexes are determined and the analytical aspects of the complexation reaction are demonstrated. A critical investigation has also been presented of the solution equilibria and stability of the mixed complex of mercury(II) withhyna and thiosalicylic acid (tsa). The various complex transitions leading to the formation of the 1 : 1 : 1 Hg(tsa)(hyna) ternary complex in solution are investigated. The non-charged mono-ligand complex Hg(hyna) is used for UV-spectrophotometric determination of mercury atpH 4.5–5 (max=325nm, =0.8·104lmol–1cm–1). The system obeyed Beer's law up to 36.1 µg ml–1 of Hg(II). The optimum concentration range (Ringbom) is between 6 and 28.5µg ml–1. Interference caused by a number of ions was masked by the addition of fluoride ions.
Lösungsgleichgewichte und Stabilitätskonstanten von Komplexen der Pyridincarbonsäuren: Die Komplexierungsreaktion von Quecksilber(II) mit 2-Hydroxynikotinsäure
Zusammenfassung Die Lösungsgleichgewichte von 2-Hydroxynikotinsäure (hyna) mit Hg(II) wurde spektrophotometrisch in 50% (v/v) Ethanol bei 20°C und einer Ionenstärke von 0.1 mol dm–3 (NaClO4) untersucht. In Abhängigkeit von der Acidität des Mediums werden drei Quecksilberkomplexe gebildet. Die grundlegenden Charakteristika der Komplexe wurden bestimmt und die analytischen Aspekte aufgezeigt. Die gemischten Komplexe von Hg(II) mithyna und Thiosalicylsäure (tsa), insbesondere die verschiedenen Komplexübergänge zum ternären 1 : 1 : 1 Hg(tsa)(hyna)-Komplex, wurden ebenfalls untersucht. Der ungeladene Monoligandenkomplex Hg(hyna) kann beipH 4.5–5 zur UV-spektroskopischen Quecksilberbestimmung eingesetzt werden (max=325nm, =0.8·104lmol–1cm–1). Das System gehorcht bis zu einer Hg(II)-Konzentration von 36.1µgml–1 dem Beerschen Gesetz. Der optimale Konzentrationsbereich (Ringbom) liegt zwischen 6 und 28.5µgml–1. Interferenzen mit einer Reihe anderer Ionen konnten durch Maskierung mit Fluoridionen umgangen werden.相似文献
138.
M. E. Kassem A. E. Hamed M. El-Osairy A. M. Okaz 《Journal of Thermal Analysis and Calorimetry》1991,37(2):341-345
A specific heat study of (Li1–xKx)2SO4 — LKS — mixed crystals has been made in a wide concentration rangex covering the temperature range 300–800 K. The phase diagram was determined. It is shown that a variation of the Li+:K+ concentration changes the critical behaviour of the specific heat. The results are discussed in terms of scattering mechanisms of energy carriers.
Zusammenfassung Bei Temperaturen zwischen 300 und 800 K wurde für einen breiten Konzentrationsbereich für x die spezifische Wärme von (Li1–xKx)2SO4-Mischkristallen untersucht und das entsprechende Phasendiagramm erstellt. Es wurde gezeigt, daß eine Änderung des Verhältnisses Li+:K+ auch das kritische Verhalten der spezifischen Wärme verändert. Die Ergebnisse werden hinsichtlich von Sreuungsmechanismen der Energieträger diskutiert.相似文献
139.
Fatimah Y. Alomari Abeer A. Sharfalddin Magda H. Abdellattif Doaa Domyati Amal S. Basaleh Mostafa A. Hussien 《Molecules (Basel, Switzerland)》2022,27(3)
Four new drug-based oxidovanadium (IV) complexes were synthesized and characterized by various spectral techniques, including molar conductance, magnetic measurements, and thermogravimetric analysis. Moreover, optimal structures geometry for all syntheses was obtained by the Gaussian09 program via the DFT/B3LYP method and showed that all of the metal complexes adopted a square-pyramidal structure. The essential parameters, electrophilicity (ω) value and expression for the maximum charge that an electrophile molecule may accept (ΔNmax) showed the practical biological potency of [VO(CTZ)2] 2H2O. The complexes were also evaluated for their propensity to bind to DNA through UV–vis absorption titration. The result revealed a high binding ability of the [VO(CTZ)2] 2H2O complex with Kb = 1.40 × 10⁶ M−1. Furthermore, molecular docking was carried out to study the behavior of the VO (II) complexes towards colon cancer cell (3IG7) protein. A quantitative structure–activity relationship (QSAR) study was also implemented for the newly synthesized compounds. The results of validation indicate that the generated QSAR model possessed a high predictive power (R2 = 0.97). Within the investigated series, the [VO(CTZ)2] 2H2O complex showed the greatest potential the most selective compound comparing to the stander chemotherapy drug. 相似文献
140.
Magda A. Abdallah 《Monatshefte für Chemie / Chemical Monthly》2001,132(8):959-965
Summary. The reaction of 3-amino-2-thioxo-4(1H)-quinazolinone or its 2-methylthio derivative with hydrazonoyl halides in the presence of ethanol and triethylamine affords
6H-[1,2,4,5]tetrazino[3, 2-b]quinazolin-6-ones.
Received January 2, 2001. Accepted (revised) April 11, 2001 相似文献