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61.
El Houssine MABROUK Nadia ARROUSSE Adil KORCHI Mohammed LACHGAR Ahmad OUBAIR Abdelrhani ELACHQAR Mohamed JABHA Mohammed LACHKAR Fadoua El HAJJAJI Zakia RAIS Mustapha TALEB 《高等学校化学研究》2020,36(6):1183-1189
The α-amino acid derivatives constitute a class of compounds of particular medicinal and synthetic attention and considerable interest has been devoted to their synthesis in recent years. In the present work, we develop the computational study of the synthesis reaction of new pyrazolyl α-amino esters derivatives using the Gaussian 09 based on the DFT/B3LYP density functional theory method, with the base 6-31G(d, p) to ensure the possibility of carrying out these reactions within the laboratory of synthesis. Indeed, this research has encouraged us to establish an economical synthesis strategy of these products in overall yields of 73.5% to 87% to have access to new active biomolecule through the O-alkylation reaction between methyl α-azidoglycinate N-benzoylated and primary pyrazole alcohols[(3,5-dimethyl-1H-pyrazol-1-yl)methanol, (1H-pyrazol-1-yl)methanol and (3-ethoxy-5-methyl-1H-pyrazol-1-yl)methanol] under different operating conditions. The structure of the prepared heterocyclic systems was characterized by conventional spectroscopic techniques, like 1H NMR, 13C NMR, and MS. The results revealed that the experimental study is in good correlation with the computational one. 相似文献
62.
63.
JPC – Journal of Planar Chromatography – Modern TLC - A simple, rapid, and selective densitometric thin-layer chromatographic (TLC) method has been established and validated for... 相似文献
64.
A family of Hecke C*-algebras can be realised as crossed productsby semigroups of endomorphisms. It is shown by dilating representationsof the semigroup crossed product that the category of representationsof the Hecke algebra is equivalent to the category of continuousunitary representations of a totally disconnected locally compactgroup. 相似文献
65.
Most K Köpke S Dall'Antonia F Mösch-Zanetti NC 《Chemical communications (Cambridge, England)》2002,(16):1676-1677
Molybdenum dioxo compounds [MoO2Cl(eta 2-pz)] and [MoO2(eta 2-pz)2] with pz = eta (2)-3,5-di-tert-butylpyrazolate have been synthesized; crystallographic data, catalytic activity, and oxo transfer properties are described. 相似文献
66.
Poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) (PHBV) was covered with an hydrophobic layer from plasma polymerization of tetradecafluorohexane, octadecafluorooctane, 3,3,4,4,5,5,6,6,6-nonafluoro-hex-1-ene and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-oct-1-ene. The water contact angle increased from 74° for untreated films to 98° for the treated films and the surface energy decreased from 40.9 to 18.8 mJ m−2. XPS analysis showed the introduction of 54% fluorine and 3-7% oxygen, the binding energies were assigned to chemically differently bonded carbon atoms. CF2/CF3 molar ratio in plasma layers was lower than that in the monomers due to molecular fragmentation, however the extent of monomer structure retention in PFH, PFO saturated chains is higher than in NFH, TDFO unsaturated chains. Biodegradation tests under aerobic conditions showed that the fluorinated plasma layer inhibited the biodegradation of the PHBV film underneath. 相似文献
67.
Scalora M Syrchin MS Akozbek N Poliakov EY D'Aguanno G Mattiucci N Bloemer MJ Zheltikov AM 《Physical review letters》2005,95(1):013902
A new generalized nonlinear Schr?dinger equation describing the propagation of ultrashort pulses in bulk media exhibiting frequency dependent dielectric susceptibility and magnetic permeability is derived and used to characterize wave propagation in a negative index material. The equation has new features that are distinct from ordinary materials (mu=1): the linear and nonlinear coefficients can be tailored through the linear properties of the medium to attain any combination of signs unachievable in ordinary matter, with significant potential to realize a wide class of solitary waves. 相似文献
68.
69.
We analyze the role and influence of a tradition of research linked to the concept of
primary matter
in nineteenth-century studies on the nature of the elements.The suggestion of William Prout
(1785-1850) in 1816 that the atomic weights of pure chemical elements are whole numbers and
multiples of the atomic weight of hydrogen, taken as unity, was met with serious confutations,which
in turn prompted several attempts to save Prouts hypothesis.We discuss these attempts in detail
and the objections raised against them, for instance by Dmitry Ivanovich Mendeleev (1834-1907).
We pay particular attention to the use of spectroscopy as a method for proving the existence of
elementary forms of matter inside atoms. Leaders in this field of research were two English scientists,
the astrophysicist Norman Lockyer (1836-1920) and the chemist William Crookes (1832-
1919). Both of their approaches involved the idea of primary matter. However, while Crookess
approach proved to be incorrect, Lockyers ideas survived for several years and supported the discovery
of the electron by J.J.Thomson (1856-1940). 相似文献
70.
The longitudinal ultrasonic attenuation measurements have been made using pulse echo method at fundamental frequencies of 2, 4, 6 and 8 MHz in 20WO3–(80−x) TeO2–xPbO ternary tellurite glasses (x=10, 12.5, 15, 17.5 and 20 mol%) in the temperature range 160–280 K. The results showed the presence of a broad peak which shifts to higher temperature with increasing frequency. The ultrasonic attenuation peaks suggest that the experimental behavior is controlled by thermally activated structural relaxations. The internal friction, acoustic activation energy, deformation potential, relaxation strength, number of loss centers and density of state have been calculated both as a function of temperature and PbO content. The acoustic activation energy was found to decrease from 0.156 to 0.135 eV with the increase of PbO content. The results showed that both the number of loss centers and their activation energy decrease with the atomic ring size. An increase in the density of state is observed with addition of PbO content at the same frequency in the whole range of temperature which is associated with structural units formed when PbO is added. 相似文献