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排序方式: 共有259条查询结果,搜索用时 78 毫秒
41.
Pushyamitra MishraHardesh K. Maurya Brijesh KumarVishnu K. Tandon Vishnu Ji Ram 《Tetrahedron letters》2012,53(9):1056-1059
An efficient and concise one pot synthesis of highly functionalized thiophenes and pyranone fused thiophenes has been delineated through base induced ring transformation of suitably functionalized 2H-pyran-2-ones by ethyl thioglycolate by inter and intramolecular C-S and C-C bond formation. 相似文献
42.
Vishnu K. Tandon Anoop K. Awasthi Hardesh K. Maurya Pushyamitra Mishra 《Journal of heterocyclic chemistry》2012,49(2):424-427
Beckmann rearrangement of (E)‐4‐chromanone oxime, (E)‐5‐oximino‐3,4‐dihydro‐1(2H)‐benzoxepines, and (E)‐5‐oximino‐3,4‐dihydro‐1(2H)‐benzothiepine are catalyzed by InBr3 and AgOTf in refluxing acetonitrile resulting in the formation of pharmaceutically active heterocycles benzoxazepin‐4‐one, 5‐oxo‐benzoxazocines, and 5‐oxo‐benzothiazocine derivative, respectively, in excellent yield. J. Heterocyclic Chem., (2012). 相似文献
43.
A single layer of the Li‐Al layered double hydroxide (LDH) can be considered to be a structural synthon that can be stacked in a number of ways to give rise to the polytypes of the Li‐Al LDH family. The topotactic imbibition of lithium into gibbsite and bayerite precursors gives rise to crystalline 2H and 1M1 polytypes respectively. In contrast the sample formed through a gel to crystallite route is found to be a 1M1 polytype with stacking disorders whose local symmetry corresponds to the 1M2 polytype. On heating, a solid‐solid 1M1→1H polytype transformation is observed. 相似文献
44.
Vishnu M Bannur 《Pramana》2001,57(4):755-761
We derive relativistic fluid set of equations for neutrinos and electrons from relativistic Vlasov equations with Fermi weak
interaction force. Using these fluid equations, we obtain a dispersion relation describing neutrino beam plasma instability,
which is little different from normal dispersion relation of streaming instability. It contains new, nonelectromagnetic, neutrino-plasma
(or electroweak) stable and unstable modes also. The growth of the instability is weak for the highly relativistic neutrino
flux, but becomes stronger for weakly relativistic neutrino flux in the case of parameters appropriate to the early universe
and supernova explosions. However, this mode is dominant only for the beam velocity greater than 0.25c and in the other limit electroweak unstable mode takes over. 相似文献
45.
AnilKumar V.Vishnu B. 《计算数学(英文版)》2004,22(3):403-406
In this paper a summation formula for finding the surface area of general ellipsoids is derived. 相似文献
46.
Kaviyarasi Renu Anirban Goutam Mukherjee Uddesh Ramesh Wanjari Sathishkumar Vinayagam Vishnu Priya Veeraraghavan Balachandar Vellingiri Alex George Ricardo Lagoa Kamaraj Sattu Abhijit Dey Abilash Valsala Gopalakrishnan 《Molecules (Basel, Switzerland)》2022,27(17)
Heavy metals and metalloids like cadmium, arsenic, mercury, and lead are frequently found in the soil, water, food, and atmosphere; trace amounts can cause serious health issues to the human organism. These toxic trace elements (TTE) affect almost all the organs, mainly the heart, kidney, liver, lungs, and the nervous system, through increased free radical formation, DNA damage, lipid peroxidation, and protein sulfhydryl depletion. This work aims to advance our understanding of the mechanisms behind lipid accumulation via increased free fatty acid levels in circulation due to TTEs. The increased lipid level in the myocardium worsens the heart function. This dysregulation of the lipid metabolism leads to damage in the structure of the myocardium, inclusive fibrosis in cardiac tissue, myocyte apoptosis, and decreased contractility due to mitochondrial dysfunction. Additionally, it is discussed herein how exposure to cadmium decreases the heart rate, contractile tension, the conductivity of the atrioventricular node, and coronary flow rate. Arsenic may induce atherosclerosis by increasing platelet aggregation and reducing fibrinolysis, as exposure interferes with apolipoprotein (Apo) levels, resulting in the rise of the Apo-B/Apo-A1 ratio and an elevated risk of acute cardiovascular events. Concerning mercury and lead, these toxicants can cause hypertension, myocardial infarction, and carotid atherosclerosis, in association with the generation of free radicals and oxidative stress. This review offers a complete overview of the critical factors and biomarkers of lipid and TTE-induced cardiotoxicity useful for developing future protective interventions. 相似文献
47.
Chapala Vijaya Lakshmi Katari Naresh Kumar Malavattu Giri Prasad Kerru Nagaraju Reddy Pedavenkatagari Narayana Marisetti Vishnu Murthy 《Russian Journal of General Chemistry》2021,91(5):932-938
Russian Journal of General Chemistry - Large-scale enantioselective synthesis of the chiral amine unit of HCV NS5A inhibitor Elbasvir has been accomplished in six steps, with 55% overall yield. The... 相似文献
48.
Vishnu Chauhan T. Gupta Paramjit Singh P.D. Sahare N. Koratkar Rajesh Kumar 《Physics letters. A》2019,383(9):898-907
The calibrated and controlled swift heavy ions (SHI) beam irradiation generate defects which can cause modifications in various properties of the materials such as structural, optical, magnetic, morphological, and chemical etc. The passage of ion through the target material causes the nuclear energy losses () and electronic energy losses (). The dominates over in SHI irradiation. In the present study, ZrO2 thin films were grown on silicon and glass substrate by using RF sputtering deposition technique. For the purpose of modifications induced by swift heavy ions, these films were irradiated by a 120 MeV S9+ ion beam of 1 pnA current, with varying ion fluences from 5E12 to 1E13 ions/cm2, using the tandem accelerator at the Inter University Accelerator Center (IUAC), New Delhi, India. The X-ray diffraction (XRD) patterns confirmed the formation of monoclinic and tetragonal phases and it was observed that XRD peaks intensity increased up to the fluence of 5E12 ions/cm2 followed by opposite behavior at higher fluences. Atomic force microscope (AFM) study revealed the increased surface roughness after SHI irradiation. In addition to it, the formation of electronic transition states in optical band gap region and enhancement of absorption edge was observed from UV-visible spectroscopy (UV-Vis) results due to which direct band gap energy value decreased from those of un-irradiated samples. Photoluminescence (PL) broad emission spectra were determined using the excitation wavelength at 290 nm with the prominent peak at 415 nm which can be ascribed to Zr vacancies due to band edge emission as a result of free-exciton recombination. Rutherford backscattering spectrometry (RBS) technique was used for depth profiling and elemental composition in zirconia thin films. The expected role of electronic energy loss during ion irradiation is to modify the properties of the material has been discussed. 相似文献
49.
The multiple orders per job (MOJ) scheduling problem is presented for the batch-processing environment such as that exemplified by diffusion ovens. A mixed-integer
programming formulation is presented for the incompatible job family case wherein only jobs that belong to the same family
may be grouped together in a production batch. This optimization formulation is tested through an extensive experimental design
with the objective of minimizing total weighted tardiness (maximizing on-time delivery performance). Optimal solutions are
achievable for this initial set of 6-to-12 order problems, but it is noted that the optimization model takes an unreasonable
amount of computation time, which suggests the need for heuristic development to support the analysis of larger, more practical
MOJ batch scheduling problems. A number of simple heuristic approaches are investigated in an attempt to find near-optimal
solutions in a reasonable amount of computation time. It is seen that a combination of the heuristics produces near-optimal
solutions for small order problems. Further testing proves that these heuristic combinations are the best for large order
problems as well. 相似文献
50.
G. K. Kiran N. Munichandraiah P. Vishnu Kamath 《Journal of Solid State Electrochemistry》2018,22(12):3833-3843
Conversion anodes comprising non-stoichiometric black NiO suffer severe capacity fading in Li-ion batteries despite having a high Li+ ion diffusion coefficient. We attribute this capacity fading to (i) its small crystallite size (~?8 nm) and (ii) high charge transfer resistance (Rct ~?60–180 Ω cm2). Small crystallites enhance grain boundaries which promote Li+ ion diffusion without efficient material utilization. In contrast, the stoichiometric green NiO anodes deliver a stable capacity of 280 mAh g?1 over 50 charge-discharge cycles. The comparatively higher capacity of green NiO can be explained from its (i) large crystallite size (~?104 nm) and (ii) negligible Rct values. 相似文献