排序方式: 共有93条查询结果,搜索用时 41 毫秒
1.
Awadallah Adel M. El-Halabi Nabil M. Ferwanah Abdel-Rahman S. Awad Boshra M. 《Transition Metal Chemistry》2004,29(3):280-283
3-Acetyl-1,2,4-triazole hydrazones (3b,c) and methylhydrazone (4d) were prepared by reacting triazoles (1b–d) with an excess of hydrazines at room temperature. Square planar nickel(II) complexes (8b,c) of (3b,c) were obtained from their reaction with Ni(OAc)2 in a 2:1 mol ratio in EtOH at room temperature. The spectral data suggest structures (8b,c) for the obtained complexes, which result from ring opening of the triazole ring followed by recyclization to give the 5-arylhydrazono-2,3-dihydro-4H-1,2,4-triazine ligand (7b,c). The reaction of triazole methylhydrazone (4d) with Ni(OAc)2 in EtOH resulted, however, in the formation of the starting triazole (1d). All new compounds were characterized by elemental analysis, i.r., 1H-n.m.r. 13C-n.m.r. and hrms. 相似文献
2.
Sanaei-Rad Saleheh Saeidiroshan Hakimeh Mirhosseini-Eshkevari Boshra Ghasemzadeh Mohammad Ali 《Research on Chemical Intermediates》2021,47(5):2143-2159
Research on Chemical Intermediates - Regarding the significance of medicinal and pharmacological sciences, we explored one-pot multicomponent reaction of aromatic aldehydes, aryl amines,... 相似文献
3.
Azadi Mahboobeh Olya Mohammad Javad Vahedi Samaneh Sangani Neda Fazeli 《Russian Journal of Applied Chemistry》2017,90(7):1181-1187
Russian Journal of Applied Chemistry - Titanium dioxide (TiO2) is widely used in the paint industry as a white pigment. To reduce the high cost of TiO2, mineral fillers such as different calcites... 相似文献
4.
Mohammad Ali Ghasemzadeh Boshra Mirhosseini‐Eshkevari Mohammad Hossein Abdollahi‐Basir 《应用有机金属化学》2019,33(1)
A novel and simple approach for the efficient and rapid synthesis of pyrano[2,3‐c]‐pyrazoleshas been accomplished via the four‐component condensation reaction of malononitrile, hydrazine hydrate, ethyl acetoacetate, and substituted aldehydes using MIL‐53(Fe) metal–organic framework (MOF) as a catalyst in ethanol at room temperature. Recycling studies have shown that the MIL‐53(Fe) can be readily recovered and reused six times without significant loss of its activity. The present protocol offers the advantages including short reaction times, simple workup, high yields, elimination of toxic solvents, no chromatographic purification and recoverability of the catalyst. Also, the catalyst was fully characterized by SEM, EDX, FT‐IR, XRD, TGA and TEM analysis. 相似文献
5.
The efficient and one-pot synthesis of 4-substituted-1,2,4-triazolidin-3,5-dione derivatives(4-substituted urazoles) via combination of triphosgene, substituted anilines, and ethyl carbazate in the presence of cesium carbonate is presented. 相似文献
6.
Being the simplest element with just one electron and proton the electronic structure of a single Hydrogen atom is known exactly. However, this does not hold for the complex interplay between them in a solid and in particular not at high pressure that is known to alter the crystal as well as the electronic structure and eventually causes solid hydrogen to become metallic. In spite of intense research efforts the experimental realization of metallic hydrogen, as well as the theoretical determination of the crystal structure has remained elusive. Here we present a computational study showing that the distorted hexagonal P63/m structure is the most likely candidate for Phase III of solid hydrogen. We find that the pairing structure is very persistent and insulating over the whole pressure range, which suggests that metallization due to dissociation may precede eventual bandgap closure. Due to the fact that this not only resolve one of major disagreement between theory and experiment, but also excludes the conjectured existence of phonon-driven superconductivity in solid molecular hydrogen, our results involve a complete revision of the zero-temperature phase diagram of Phase III. 相似文献
7.
Systematic first principle calculations have been used to explain the dangling bonds behaviour in the rolling up of a boron nitride nanoribbon (BNNR) to construct a single-walled boron nitride nanotube (BNNT). We found in armchair BNNR two degenerate dangling bonds split and move up to higher energies due to symmetry breaking of system. While in zigzag BNNR changing the topology of system does not affect on metallic features of the band structure, but in unzipped BNNT case a metallic-semimetallic phase transition occurs. Considering the width dependent electronic properties of hydrogen passivated armchair BNNRs, exhibit zigzag behaviour of energy gap in agreement with previous results. 相似文献
8.
Recently the Hyers–Ulam stability of the quadratic functional equation $ f(kx+y)+f(kx+\sigma (y))- 2k^2 f(x)-2f(y)=0 $ where $\sigma $ is an involution of the normed space $E$ and $k$ is a fixed positive integer greater that 1, has been proved in the earlier work. In this paper, using fixed point and direct methods, we prove the Hyers–Ulam stability of the above functional equation in non-Archimedean normed spaces. 相似文献
9.
Hojjatollah Nazari Shohreh Azadi Shadie Hatamie Mahsa Soufi Zomorrod Khadijeh Ashtari Masoud Soleimani Simzar Hosseinzadeh 《先进技术聚合物》2019,30(8):2086-2099
The graphene‐based nanocomposites are considered as great candidates for enhancing electrical and mechanical properties of nonconductive scaffolds in cardiac tissue engineering. In this study, reduced graphene oxide‐silver (rGO‐Ag) nanocomposites (1 and 2 wt%) were synthesized and incorporated into polyurethane (PU) nanofibers via electrospinning technique. Next, the human cardiac progenitor cells (hCPCs) were seed on these scaffolds for in vitro studies. The rGO‐Ag nanocomposites were studied by X‐ray diffraction (XRD), Raman spectroscopy, and transmission electron microscope (TEM). After incorporation of rGO‐Ag into PU nanofibers, the related characterizations were carried out including scanning electron microscope (SEM), TEM, water contact angle, and mechanical properties. Furthermore, PU and PU/nanocomposites scaffolds were used for in vitro studies, wherein hCPCs showed good cytocompatibility via 3‐(4, 5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) assay and considerable attachment on the scaffold using SEM studies. Real‐time polymerase chain reaction (PCR) and immunostaining studies confirmed the upregulation of cardiac specific genes including GATA‐4, T‐box 18 (TBX 18), cardiac troponin T (cTnT), and alpha‐myosin heavy chain (α‐MHC) in the PU/rGO‐Ag scaffolds in comparison with neat PU ones. Therefore, these nanofibrous rGO‐Ag–reinforced PU scaffolds can be considered as suitable candidates in cardiac tissue engineering. 相似文献
10.
We apply a variational wave function capable of describing qualitatively and quantitatively the so-called "resonating valence bond" (RVB) in realistic materials, by improving standard ab initio calculations by means of quantum Monte Carlo methods. In this framework we clearly identify the Kekulé and Dewar contributions to the chemical bond of the benzene molecule and establish the corresponding RVB energy of these structures (?0.01 eV/atom). We apply this method to unveil the nature of the chemical bond in undoped graphene, providing an estimate of the RVB energy gain, and show that this picture remains only within a small "resonance length" of a few atomic units. 相似文献