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排序方式: 共有298条查询结果,搜索用时 15 毫秒
61.
62.
Sabah Karem J. Zahid N. Idayu Hashim Rauzah 《Research on Chemical Intermediates》2021,47(7):2653-2667
A series of new mix aza- and thia-macrocyclic glycolipids (9, 10, 16 and 17) have been synthesized and their enantiomeric selectivity was studied. The synthesis of the macrocycles involved a simple protection of two hydroxyl groups of the glycolipids followed by building up the mix-heteroatom macrocyclic in simple sequences. The macrocycles and previously investigated analogues (18, 19, 20 and 21) have been applied as phase transfer catalysts in the enantioselective Michael addition of 2-nitropropane to chalcone and showed good-to-excellent enantiomer excess (ee). Among the catalysts, the galactose aza-crown ether-based glycolipid 21 proved to be the most effective with 90% ee.
Graphic abstract63.
Crude palm oil contains 600 to 1000 ppm of tocols in the form of tocopherols and tocotrienols. These palm tocols have been isolated and analyzed in the past by various chromatographic techniques such as open column chromatography, high-performance liquid chromatography, as well as thin-layer chromatography. Supercritical fluid chromatography (SFC) has emerged as a more advanced chromatographic technique in recent years. The tocols present in palm oil are successfully isolated using SFC. Identification of these tocols is supported by various spectroscopic techniques such as 1H NMR, 13C NMR, and mass spectrometry. 相似文献
64.
Gopinath Subash C. B. Perumal Veeradasan Balakrishnan S.R. Md Arshad M. K. Lakshmipriya Thangavel Haarindraprasad R. Hashim Uda 《Mikrochimica acta》2017,184(11):4425-4431
Microchimica Acta - The authors describe an impedimetric nanosensor for aptamer-mediated detection of ATP. A triangular junction of polysilicon substrate is used as a transducer. The aptamer was... 相似文献
65.
Sampreeth Thayyil Yukinori Nishigami Md. Jahirul Islam P. K. Hashim Ken'ya Furuta Kazuhiro Oiwa Jian Yu Min Yao Toshiyuki Nakagaki Nobuyuki Tamaoki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(30):e202200807
Adenosine triphosphate (ATP) is the energy source for various biochemical processes and biomolecular motors in living things. Development of ATP antagonists and their stimuli-controlled actions offer a novel approach to regulate biological processes. Herein, we developed azobenzene-based photoswitchable ATP antagonists for controlling the activity of motor proteins; cytoplasmic and axonemal dyneins. The new ATP antagonists showed reversible photoswitching of cytoplasmic dynein activity in an in vitro dynein-microtubule system due to the trans and cis photoisomerization of their azobenzene segment. Importantly, our ATP antagonists reversibly regulated the axonemal dynein motor activity for the force generation in a demembranated model of Chlamydomonas reinhardtii. We found that the trans and cis isomers of ATP antagonists significantly differ in their affinity to the ATP binding site. 相似文献
66.
M.N. MahmudI. Hashim 《Physics letters. A》2011,375(24):2382-2393
Feedback control on thermal convection in a fluid-saturated porous medium is investigated based on the approach of dynamical systems. A low dimensional Lorenz-like model was obtained using the Galerkin truncated approximation. The possible suppression or enhancement of chaotic convection is demonstrated. 相似文献
67.
68.
P. S. Pereira Silva Raza Murad Ghalib Sayed Hasan Mehdi Rokiah Hashim Othman Sulaiman Ali Jawad 《Journal of chemical crystallography》2010,40(12):1150-1154
Abstract
Cyclohexyl N-phenylcarbamate, C13H17NO2 (I), which is a useful target for biotransformations by fungi, has been synthesized and the structure has been solved by X-ray diffraction. The crystals are triclinic, space group P [`1] \bar{1} , with a = 5.2581 (2) ?, b = 9.5080 (3) ?, c = 12.6165 (4) ?, α = 70.544 (2)°, β = 89.075 (2)°, γ = 80.447 (2)°, M r = 219.28, V = 585.96 (3) ?3, Z = 2 and R = 0.065. In the title compound the phenyl ring makes a dihedral angle of 30.68(7)° with the carbamate group The molecules are linked into infinite chains via N–H···O hydrogen bonds along the a axis. These hydrogen-bonded chains are further linked by weaker C–H···π interactions. Quantum-mechanical ab initio calculations for the free molecule reproduce well the observed bond lengths and valency angles but show that the crystal packing might be responsible for the rotation of the phenyl ring out of the carbamate plane in the solid state conformation. 相似文献69.
The magnetohydrodynamics flow and heat transfer in a thin liquid film over an unsteady elastic stretching surface are analyzed by the homotopy analysis method. A more general surface temperature is taken into consideration. The effects of various parameters in this study are discussed and presented graphically. The good agreement between the analytic series solutions and the previous numerical results shows the effectiveness of HAM to this problem. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
70.
Ravindra D. Jadhav Hitesh D. Mistry Hashim Motiwala Kishorkumar S. Kadam Shivaji Kandre Amol Gupte Ashok K. Gangopadhyay Rajiv Sharma 《Journal of heterocyclic chemistry》2013,50(4):774-780
Hydroxy (tosyloxy) iodobenzene (HTIB), a hypervalent iodine reagent, has been extensively used for oxidative transformations. We have developed a one‐pot synthesis wherein aldoximes when reacted with alkynes in the presence of HTIB result in the direct formation of isoxazoles. This simple and straightforward reaction allows for ease of purification while leading to the formation of high purity 3,5‐disubstituted isoxazoles in moderate yields. 相似文献