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排序方式: 共有719条查询结果,搜索用时 359 毫秒
711.
712.
Yehia A. Ibrahim Ahmed H. M. Elwahy Hishmat R. Hanna Suzan K. Khella 《Supramolecular chemistry》2013,25(1):83-89
Abstract Four new compounds with 14-crown-4 attached to spirocyclopentane or spirocyclohexane were synthesized and tested for potentiometric selectivity for lithium ion in polyvinyl chloride membrane electrodes. Four plasticizers were studied and the addition of tri-octylphosphine oxide (TOPO) was investigated. One ionophore exhibited a sodium/lithium selectivity, Kpot Li,Na by the matched potential method of 0.0028 in the presence of 1% TOPO, using o-nitro-phenylphenyl ether as plasticizer. Selectivities are reported for sodium, potassium, nickel, cobalt, barium and calcium. 相似文献
713.
Suzan A. Khayyat 《Journal of Saudi Chemical Society》2013,17(1):61-65
It has been reported that trans-cinnamaldehyde, eugenol and safrole inhibited bacteria and fungi growth in vivo mode. In order to improve their biological activity, dimeric cinnamaldehyde, eugenol and safrole have been photosynthesized. The photosynthesis compounds were 4,6-diphenyl-1,2-dioxane-3,5-dicarboxaldehyde, 4,4-(cyclobutone-1,3-diyl bis(methylene))bis(2-methoxyphenal), and 3,6-bis(benzo[d][1,3]dioxol-5-ylmethyl)-1,2-dioxane. These new dimeric compounds strongly inhibited Candida albicans growth more than the monomers. 相似文献
714.
Mustafa Güler Derya Çelik 《International Journal of Mathematical Education in Science & Technology》2019,50(1):82-99
There is a growing emphasis in the teaching profession on pedagogical content knowledge (PCK) as an important knowledge component. The study reported in this article investigates Turkish prospective mathematics teachers’ mathematics teaching knowledge in the numbers content domain. A series of 10 open-ended scenario-type questions were adopted to challenge 83 prospective mathematics teachers’ knowledge of the learner and presentation of content in the context of PCK. The participants’ responses were analysed by means of rubrics and scoring guides developed by the researchers. The results showed that many of the future teachers performed well in determining what misconceptions students might express in the given scenarios. However, a majority of the participants performed poorly on presentation of content in terms of instructional strategies. In line with these results, the authors offer some suggestions for teacher training programmes. 相似文献
715.
The complete coding sequences of the polA genes from seven thermophilic Geobacillus species, isolated from hot springs of G?nen and Hisaralan in Turkey, were cloned and sequenced. The polA genes of these Geobacillus species contain a long open reading frame of 2,637 bp encoding DNA polymerase I with a calculated molecular mass of 99 kDa. Amino acid sequences of these Geobacillus DNA polymerases are closely related. The multiple sequence alignments show all include the conserved amino acids in the polymerase and 5'-3' exonuclease domains, but the catalytic residues varied in 3'-5' exonuclease domain of these Geobacillus DNA polymerases. One of them, DNA polymerase I from Geobacillus kaue strain NB (Gkaue polI) is purified to homogeneity and biochemically characterized in vitro. The optimum temperature for enzymatic activity of Gkaue polI is 70 °C at pH 7.5-8.5 in the presence of 8 mM Mg(2+) and 80-100 mM of monovalent ions. The addition of polyamines stimulates the polymerization activity of the enzyme. Three-dimensional structure of Gkaue polI predicted using homology modeling confirmed the conservation of all the functionally important regions in the polymerase active site. 相似文献
716.
In this paper, the graybody radiation phenomena has been handled with the help of fractional calculus. Fractional definition of graybody spectrum has been written in terms of Mittag‐Leffler function. The obtained data from fractional calculus approximation for nearly 2.87 × 107 K have been compared with literature values and standard blackbody radiation. 相似文献
717.
A general and convenient route for the synthesis of 2,5-di[1-methyl-1-arylcyclobutane-3-yl]- thiophenes 4a–c and bis[1-methyl-1-arylcyclobutane-3-yl]-2-(2-oxyethtylamido)thiazole sulfides 7a–c is reported. The characterization of these compounds was obtained by elemental analyses, IR, 13C, and 1H NMR techniques. © 2003 Wiley Periodicals, Inc. 15:26–31, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/.hc10207 相似文献
718.
In this study, Darcy Forchheimer flow paradigm, which is a useful paradigm in fields such as petroleum engineering where high flow velocity effects are common, has been analyzed with artificial intelligence approach. In this context, first of all, Darcy–Forchheimer flow of Ree–Eyring fluid along a permeable stretching surface with convective boundary conditions has been examined and heat and mass transfer mechanisms have been investigated by including the effect of chemical process, heat generation/absorption, and activation energy. Cattaneo–Christov heat flux model has been used to analyze heat transfer properties. Within the scope of optimizing Darcy–Forchheimer flow of Ree–Eyring fluid; three different artificial neural network models have been developed to predict Nusselt number, Sherwood number, and skin friction coefficient values. The developed artificial neural network model has been able to predict Nusselt number, Sherwood number, and skin friction coefficient values with high accuracy. The findings obtained as a result of the study showed that artificial neural networks are an ideal tool that can be used to model Darcy–Forchheimer Ree–Eyring fluid flow towards a permeable stretch layer with activation energy and a convective boundary condition. 相似文献
719.
Suzan I. Aziz Zaghloul E. Kandeel Mona M. Husein Salem El Gohary Eiman I. Abou El Maged 《Heteroatom Chemistry》1995,6(4):319-323
A new route for the synthesis of 3H-1,2,4-triazolo[1,5-a]pyridines 7a–j , 12a , b , and 17a , b utilizing the reaction of the hydrazones of cyanoethanoic acid hydrazide 3a , b with ylidene malononitriles 2a–e , malononitrile, and 3-aminocrotononitrile is described. 相似文献