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1.
Summary Optically pure (+)-beta-eudesmol is a possible starting material for the synthesis of several termite defense compounds. A
two step procedure for the isolation of gram quantities of (+)-beta-eudesmol from commercially availableAmyris balsamifera oil (syn. West Indian sandalwood oil), containing 8% beta-eudesmol, was developed. Step one consisted of an efficient vacuum
distillation of the total oil. Step two was a medium pressure LC separation with an AgNO3 impregnated silica gel stationary phase. Several other separation procedures failed due to the presence of many closely related
sesquiterpene alcohols (75% of the oil). 相似文献
2.
Tarek M. Madkour Rasha A. Azzam 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2526-2536
Polyurethane elastomers of a controlled molecular architecture were synthesized using a two‐step polymerization technique. The building blocks of the elastomeric materials included urea–urethane prepolymers end‐capped with diisocyanate groups and had an exact number of urea groups at both ends. Two‐dimensional bifurcated hydrogen‐bonding networks incorporating the urea groups were, with differential scanning calorimetric and dynamic mechanical thermal analyzer techniques, responsible for the increase in the glass‐transition temperature (Tg) of the hard block and sharp interface morphology between the pure “hard” domains and pure “soft” domains. The higher extent of the phase separation between the two phases contributed to higher elastic moduli for the hard blocks and higher tensile strength for the elastomeric samples. Higher elongation values were attributed to the liberation of the elastomeric chain ends that otherwise would have been constrained in the interface region. The higher Tg values of the hard blocks corresponded to an increase in the hardness values and a decrease in the tear‐strength values. The increase in the amount of urea groups within the hard segments, as a result of the increased amount of water and blowing catalyst, resulted in elastomeric foams with higher open‐cell content. This resulted in lower resilience values as measured using the pendulum rebound test and was attributed to the ability of the open cells to absorb and dissipate energy. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2526–2536, 2002 相似文献
3.
The action of 2-mercaptoacetic acid, thiosemicarbazide and hydrazine hydrate on the titled compound 1 is studied. On the other hand, the behaviour of the titled compound towards thiourea, ethyl acetoacetate and malononitrile under Michael's conditions is reported. The structure of the new heterocycles 2 - 8 is discussed in the light of IR and 1HNMR spectra. 相似文献
4.
Loutfy H. Madkour Amera M. Hassanein Mohamed M. Ghoneim Safwat A. Eid 《Monatshefte für Chemie / Chemical Monthly》2001,132(2):245-258
Summary. The inhibition of corrosion of iron in 2 M nitric acid and 2 M sulfuric acid solutions by substituted phenylhydantoin, thiohydantoin, and dithiohydantoin compounds was measured using thermometric,
weight loss, and polarization methods. The three methods gave consistent results. The polarization curves indicated that the
hydantoin compounds act as mixed-type inhibitors. The adsorption of the inhibitors were found to obey the Temkin adsorption isotherm. The higher inhibition efficiency of the additives in nitric with respect to sulfuric acid solution may
be attributed to the reduced formation of soluble quaternary nitrogen salts in nitric acid medium, favouring adsorption of
the parent additive on the metal surface. The obtained results indicate that the corrosion rate of iron in both acids increases
with increasing temperature, both in absence and presence of the tested inhibitors. Kinetic-thermodynamic model functions
and Temkin isotherm data are compared and discussed. The synergistic effect of halide anions on the inhibition efficiency of the hydantoin
compounds was also investigated.
Received June 5, 2000. Accepted (revised) September 13, 2000 相似文献
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6.
Mohammed I. El-Gamal Nada H. Mewafi Nada E. Abdelmotteleb Minnatullah A. Emara Hamadeh Tarazi Rawan M. Sbenati Moustafa M. Madkour Seyed-Omar Zaraei Afnan I. Shahin Hanan S. Anbar 《Molecules (Basel, Switzerland)》2021,26(23)
HER4 is a receptor tyrosine kinase that is required for the evolution of normal body systems such as cardiovascular, nervous, and endocrine systems, especially the mammary glands. It is activated through ligand binding and activates MAPKs and PI3K/AKT pathways. HER4 is commonly expressed in many human tissues, both adult and fetal. It is important to understand the role of HER4 in the treatment of many disorders. Many studies were also conducted on the role of HER4 in tumors and its tumor suppressor function. Mostly, overexpression of HER4 kinase results in cancer development. In the present article, we reviewed the structure, location, ligands, physiological functions of HER4, and its relationship to different cancer types. HER4 inhibitors reported mainly from 2016 to the present were reviewed as well. 相似文献
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8.
S. A. El-Wakil M. A. Madkour A. Abu El-Ela A. M. El-Grayhy 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1993,44(2):282-289
A direct operational method is used to transform the collision integral in the Telford coagulation equation for aerosols to a polynomial in derivatives with respect to volume. This polynomial is approximated by the Padé approximation technique. This procedure reduces the integro-differential form to a partial differential equation which is solved by the similarity method. Exact as well as approximate expressions for the particle size distribution are obtained. 相似文献
9.
M. F. Madkour Hassan Mahamed A. E. Sayed A. Hamed Ashraf M. Gaber Adel A. Hataba Abd El-Khalik 《中国化学》1991,9(3):262-269
The title compound was subjected to react with some electrophiles and nucleophiles, such as alkyl halides, ethyl chloroacetate or amines, hydrazines etc. The resulting compounds were used in further syntheses for the purpose of obtaining some new types of heterocycles with possible biological and pharmaceutical activities. 相似文献
10.
M. A. I. Salem H. M. F. Madkour M. I. Marzouk M. E. Azab N. F. H. Mahmoud 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):2596-2614
The pyrimidinethiones have wide biological and pharmaceutical activities, that have attracted considerable interest in recent years especially as antiviral inhibiting production of hepatitis B virus (HBV), and in vitro insulin-mimetic. Activity of the complexes of pyrimidinone derivatives evaluated from 50% inhibitory concentration promoted us to study the transformation of the 2-thioxopyrimidin-6(1H) ones to fused bi- and tri-cyclic heterocyclic compounds having the pyrimidine moieties and screening their biological activity. The reactivity of 2-mercapto-4-aryl-5-cyanopyrimidin-6(1H)ones (1) towards alkylation by different mono and bifunctional halo-organic compounds has been investigated to give S-monoalkylated products 2, 7 and 9; S- and N-dialkylated products 3, 13 and 14. Treatment of 1 and/or 2 with hydrazine hydrate as a nitrogen nucleophile have been investigated to give 4, treatment of 4 with CS2 and sodium nitrite in the presence of acetic acid (0°C) produced 1,2,4-triazolopyrimidin-5(1H)one derivatives (5)and tetrazolo[1,5-a]pyrimidin-5(1H)ones (6), respectively. Also cyclization of 7 and 9 gave [1,3]thiazolo[3,2-a]pyrimidin-5(1H)one and [1,3]thiazolo[3,2-a]pyrimidin-3,5-dione derivatives 8 and 10 respectively, treatment of 10 with aromatic aldehyde produces 11 which reacted with guanidine HCl to give pyrimido[4,5-d]thiazolo[3,2-a]pyrimidin-6(1H)one derivative 12. Reaction of 14 with o-phenylenediamine was investigated and gave [1,4]quinoxalino[2,3-b][1,3]thiazolo[3,2-a]pyrimidin-9(1H)one derivative 15. 相似文献