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131.
S.Fazal Hussain M.Tariq Siddiqui G. ManiKumar Maurice Shamma 《Tetrahedron letters》1980,21(8):723-726
Proaporphines undergo light catalyzed rearrangement. Pakistanamine () is thus converted into lumipakistanine (), while pronuciferine () and N-acetylnorpronuciferine () afford the corresponding C-9 hydroxylated aporphines and . Possible biogenetic schemes for the formation of C-8, C-9-, and C-8,9-substituted aporphines are presented. 相似文献
132.
The surface of glass beads were modified with covalently bonded poly(acrylic acid). The optimum reaction conditions were determined to graft poly(acrylic acid) effectively onto the glass surface. The dependence of the graft polymer molecular weight, grafting percentage and monomer weight conversion based on these reaction conditions were consistent with free radical kinetics. Grafting efficiency for azobisisobutyronitrile was more complex compared with the benzyl peroxide initiator system © 1997 John Wiley & Sons, Ltd. 相似文献
133.
Three new pentacyclic triterpenes ursoxy acid ( 1 ), methyl ursoxylate ( 2 ), and ursangilic acid ( 3 ), along with three known compounds dotriacontanoic acid, oleanolic acid acetate, and tetracosanoic acid, were isolated from the aerial parts of Lantana camara Linn . Structures of the new compounds were elucidated by chemical transformation and spectral studies including 1D (1H‐ and 13C‐NMR) and 2D (COSY‐45, NOESY, J‐resolved, HMQC, and HMBC) NMR spectroscopy. 相似文献
134.
An exact analytic solution of the unsteady Navier–Stokes equations is obtained for the flow caused by the non-coaxial rotations of a porous disk and a fluid at infinity. The porous disk is executing oscillations in its own plane with superimposed injection or suction. An increasing or decreasing velocity amplitude of the oscillating porous disk is also discussed. Further, it is shown that a combination of suction/injection and decreasing/increasing velocity amplitude is possible as well. In addition, the flow due to porous oscillating disk and a fluid at infinity rotating about an axis parallel to the z-axis is attempted as a second problem.
Sommario. Si studia il flusso non stazionario prodotto dall'oscillazione di un disco poroso in un fluido e si fornisce una soluzione analitica delle equazioni di Navier–Stokes. Si discute l'effetto di una suzione/iniezione e di una variazione sull'ampiezza della velocità' di oscillazione. Infine si studia il flusso dovuto alle oscillazioni non coassiali di un disco poroso e di un fluido all'infinito. 相似文献
135.
136.
A rationally mode-locked 10 GHz erbium fiber laser stabilized by a simple technique for extended time operation is described. The laser generates stable ~ 5 ps pulses that can be used in communications experiments. Back-to-back bit error rate (BER) measurements confirmed error-free operation for 6-8 hours, giving an error floor below 10 -14 . A receiver sensitivity of -19.7 dBm was achieved for BER of 10 -9 . 相似文献
137.
Umar Farooq Rizvi Hamid Latif Siddiqui Saeed Ahmad Matloob Ahmad Masood Parvez 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(10):o547-o549
Molecules of (E)‐3‐(2‐chloro‐6‐methylquinolin‐3‐yl)‐1‐(5‐iodo‐2‐thienyl)prop‐2‐en‐1‐one, C17H11ClINOS, (I), and (E)‐3‐(2‐chloro‐6‐methylquinolin‐3‐yl)‐1‐(5‐methyl‐2‐furyl)prop‐2‐en‐1‐one, C18H14ClNO2, (II), adopt conformations slightly twisted from coplanarity. Both structures are devoid of classical hydrogen bonds. However, nonclassical C—H...O/N interactions [with C...O = 3.146 (5) Å and C...N = 3.487 (3) Å] link the molecules into chains extended along the b axis in (I) and form dimers with an R22(8) motif in (II). The structural analysis of these compounds provides an insight into the correlation between molecular structures and intermolecular interactions in compounds for drug development. 相似文献
138.
The exact analytic solutions of two problems of a second order fluid in presence of a uniform transverse magnetic field are investigated. The governing equation is of fourth order ordinary differential equation and is solved using perturbation method. In the first problem we discuss the flow of a second order fluid due to non-coaxial rotations of a porous disk and a fluid at infinity. In second problem the flow of a second order conducting fluid between two infinite plates rotating about the same axis is investigated, with suction or blowing along the axial direction. For second order conducting fluid it is observed that asymptotic solution exists for the velocity both in the case of suction and blowing. 相似文献
139.
140.
The regiochemistry observed upon arylation of ambident carbanions by phenyl radicals can be readily explained by consideration of the site of greatest basicity. Thus 1,3-diphenylindenyl anion is arylated to give predominantly 1,1,3-triphenylindene despite the presumed greater stability of the intermediate leading to 1,2,3-triphenyl indene, that is, the 1,2,3-triphenylisoindene radical anion. This explanation may also account for the preference of C-alkylation rather than O-alklation of nitrocarbanions and for the absence of O-arylation in the SRN1 arylation of enolates. The lack of reactivity of other carbanions is rationalized on thermodynamic grounds. 相似文献