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排序方式: 共有273条查询结果,搜索用时 19 毫秒
101.
Kaleem Ahmad Walid Tawfik Wazirzada A. Farooq Jagdish P. Singh 《Applied Physics A: Materials Science & Processing》2014,117(3):1315-1322
In this work, alumina (Al2O3) containing different volume % of titanium carbide (TiC) ranging from 0 to 30 were consolidated by the novel spark plasma sintering. The spectroscopic analysis of the plasma generated by irradiation of laser Nd:YAG (λ = 1,064 nm) on different concentrations of the composites in air atmospheric pressure was performed. The qualitative examination of the composites confirms the presence of aluminum, titanium, and carbon as major elements, while magnesium and sodium have been found as minor trace elements. Plasma parameters were estimated by assuming the LTE conditions for optically thin plasma. The electron density and temperature were evaluated by using the Stark broadening and intensity of selected aluminum emission lines, respectively. The addition of TiC to Al2O3 shows a linear behavior with plasma temperature corroborated by the calibration curve of Ti in the composites. The results suggest that calibration curve between plasma temperature and the composites can be used to estimate different concentrations of TiC in Al2O3 without analyzing the whole elements in the composites and thus opens up new applications of LIBS in ceramic industry. 相似文献
102.
Kiran Singh Parvesh Puri Yogender Kumar Chetan Sharma 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):1462-1473
The Schiff bases (imines) HL1 and HL2 have been synthesized by the reaction of 5-bromothiophene-2-carboxaldehyde with 4-amino-5-mercapto-1,2,4-triazole and 4-amino-3-ethyl-5-mercapto-1,2,4-triazole, respectively. Organosilicon(IV) and organotin(IV) complexes having the general formulae R2MCl(L1), R2MCl(L2), R2M(L1)2, R2M(L2)2, (M = Si, Sn; R = CH3) were synthesized by the reaction of R2MCl2 with these Schiff bases in 1:1 and 1:2 molar ratio. The Schiff bases and their metal complexes have been characterized with the aid of elemental analyses, molar conductance, and spectroscopic studies, including UV, IR, 1H, 13C, MS, 29Si, and 119Sn NMR spectroscopy. On the basis of these studies, the resulting complexes have been proposed to have trigonal bipyramidal and octahedral geometries. In vitro activities of the Schiff bases and their metal complexes against some Gram positive and Gram negative bacteria and fungi have been carried out and described. 相似文献
103.
A new series of pyrido[1,2-α]benzimidazole derivatives bearing the aryloxypyrazole nucleus have been synthesized by base-catalyzed cyclocondensation reaction through multi-component reaction(MCR) approach.All the synthesized compounds were investigated against a representative panel of pathogenic strains using broth microdilution minimum inhibitory concentration(MIC) method for their in vitro antimicrobial activity.Reviewing the data,majority of the compounds were found to be active against employed pathogens.SAR study explores that antimicrobial activity is strongly depends on the nature of the substituents at the ether linked aryl ring attached to the pyrazole unit,together with the substituent present on the C5 of the benzimidazole unit. 相似文献
104.
Chetan C. Chintawar Amit K. Yadav Nitin T. Patil 《Angewandte Chemie (International ed. in English)》2020,59(29):11808-11813
Herein, we disclose the gold‐catalyzed 1,2‐diarylation of alkenes through the interplay of ligand‐enabled AuI/AuIII catalysis with the idiosyncratic π‐activation mode of gold complexes. Unlike the classical migratory‐insertion‐based approach to 1,2‐diarylation, the present approach not only circumvents the formation of direct Ar?Ar′ coupling and Heck‐type side products but more intriguingly demonstrates reactivity and selectivity complementary to those of previously known metal catalysis (Pd, Ni, or Cu). Detailed investigations to underpin the mechanistic scenario revealed oxidative addition of aryl iodides to an AuI complex to be the rate‐limiting step owing to the non‐innocent nature of the aryl alkene. 相似文献
105.
Chetan Kumar Arya Swati Yadav Jonathan Fine Ana Casanal Gaurav Chopra Gurunath Ramanathan Kutti R. Vinothkumar Ramaswamy Subramanian 《Angewandte Chemie (International ed. in English)》2020,59(39):16961-16966
N,N‐dimethyl formamide (DMF) is an extensively used organic solvent but is also a potent pollutant. Certain bacterial species from genera such as Paracoccus, Pseudomonas, and Alcaligenes have evolved to use DMF as a sole carbon and nitrogen source for growth via degradation by a dimethylformamidase (DMFase). We show that DMFase from Paracoccus sp. strain DMF is a halophilic and thermostable enzyme comprising a multimeric complex of the α2β2 or (α2β2)2 type. One of the three domains of the large subunit and the small subunit are hitherto undescribed protein folds of unknown evolutionary origin. The active site consists of a mononuclear iron coordinated by two Tyr side‐chain phenolates and one carboxylate from Glu. The Fe3+ ion in the active site catalyzes the hydrolytic cleavage of the amide bond in DMF. Kinetic characterization reveals that the enzyme shows cooperativity between subunits, and mutagenesis and structural data provide clues to the catalytic mechanism. 相似文献
106.
107.
Jagdish Mehra 《Foundations of Physics》1987,17(5):461-506
In this paper, the main outlines of the discussions between Niels Bohr with Albert Einstein, Werner Heisenberg, and Erwin Schrödinger during 1920–1927 are treated. From the formulation of quantum mechanics in 1925–1926 and wave mechanics in 1926, there emerged Born's statistical interpretation of the wave function in summer 1926, and on the basis of the quantum mechanical transformation theory—formulated in fall 1926 by Dirac, London, and Jordan—Heisenberg formulated the uncertainty principle in early 1927. At the Volta Conference in Como in September 1927 and at the fifth Solvay Conference in Brussels the following month, Bohr publicly enunciated his complementarity principle, which had been developing in his mind for several years. The Bohr-Einstein discussions about the consistency and completeness of qnautum mechanics and of physical theory as such—formally begun in October 1927 at the fifth Solvay Conference and carried on at the sixth Solvay Conference in October 1930—were continued during the next decades. All these aspects are briefly summarized. 相似文献
108.
Ajay K Bose Maghar S Manhas Shanti G Amin Jagdish C Kapur J Kreder L Mukkavilli Bhagat Ram John E Vincent 《Tetrahedron letters》1979,20(30):2771-2774
The reaction of a Schiff Base derived from veratrylamine and cinnamaldehyde with (α-methyl-β-alkoxycarbonyl)-vinylamino acetic acid (from glycine and an acetoacetate ester) in presence of a chloroformate ester and triethylamine constitutes a safe synthesis of α-vinylamino β-lactams that can be converted by literature methods to known intermediates for the synthesis of isocephalosporins and analogs. 相似文献
109.
Jagdish Kaur 《哲学杂志》2016,96(1):45-57
Thin films of Sn-doped CdSe were prepared by thermal evaporation onto glass substrates in an argon gas atmosphere and annealed at different temperatures. Structural evaluation of the films was carried out using X-ray diffraction and their stoichiometry studied by energy-dispersive X-ray analysis. The films exhibit a preferred orientation along the hexagonal direction of CdSe. The optical transmittance of the films shows a red shift of the absorption edge with annealing. The fundamental absorption edge corresponds to a direct energy gap with a temperature coefficient of 3.34 × 10?3 eV K?1. The refractive index, optical conductivity and real and imaginary parts of the dielectric constants were found to increase after annealing. The sub-band gap absorption coefficient was evaluated using the constant photocurrent method. It varies exponentially with photon energy. The Urbach energy, the density of defect states, and the steepness of the density of localized states were evaluated from the sub-band-gap absorption. 相似文献
110.
Ajay Sharma Harish Sharma Annapurna Bhargava Nirmala Sharma Jagdish Chand Bansal 《Memetic Computing》2017,9(4):311-331
The power system is a complex interconnected network which can be subdivided into three components: generation, distribution, and transmission. Capacitors of specific sizes are placed in the distribution network so that losses in transmission and distribution is minimum. But the decision of size and position of capacitors in this network is a complex optimization problem. In this paper, Limaçon curve inspired local search strategy (LLS) is proposed and incorporated into spider monkey optimization (SMO) algorithm to deal optimal placement and the sizing problem of capacitors. The proposed strategy is named as Limaçon inspired SMO (LSMO) algorithm. In the proposed local search strategy, the Limaçon curve equation is modified by incorporating the persistence and social learning components of SMO algorithm. The performance of LSMO is tested over 25 benchmark functions. Further, it is applied to solve optimal capacitor placement and sizing problem in IEEE-14, 30 and 33 test bus systems with the proper allocation of 3 and 5-capacitors. The reported results are compared with a network without a capacitor (un-capacitor) and other existing methods. 相似文献