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221.
222.
S Chakrabarty 《Pramana》1984,23(2):199-203
For a large class of phenomenological potential models motivated by quantum chromodynamics, we have studied the behaviour
of bound state masses as the constituent mass is increased and found that the mass of a quark-antiquark bound state increases
when a constituent mass is increased. It appears, for these potentials, thatd quark is heavier thanu quark.
An erratum to this article is available at . 相似文献
223.
A rapid process for decarboxylative bromination of α,β-unsaturated carboxylic acids have been developed using N,N-dibromo-p-toluenesulfonamide (TsNBr2). Treatment of cinnamic acids with TsNBr2 in presence of potassium carbonate in acetonitrile produces corresponding β-bromostyrenes at room temperature. Exclusive formation of (E)-β-bromostyrenes was observed in a stereoselective manner within a very short period of time (5–15?min). This method was further extended for obtaining 1-bromoalkynes from corresponding propiolic acids. Instantaneous formation of bromoalkynes was observed when the reaction was carried out in presence of DBU as a base in acetonitrile at room temperature. A wide variety of cinnamic acids and propiolic acids could be converted to corresponding β-bromostyrenes and 1-bromoalkynes respectively under mild reaction condition with high to excellent yield. 相似文献
224.
Stable laws can be tempered by modifying the Lévy measure to cool the probability of large jumps. Tempered stable laws retain their signature power law behavior at infinity, and infinite divisibility. This paper develops random walk models that converge to a tempered stable law under a triangular array scheme. Since tempered stable laws and processes are useful in statistical physics, these random walk models can provide a basic physical model for the underlying physical phenomena. 相似文献
225.
Aqueous methanolic potassium carbonate under reflux has been demonstrated to be a highly effective deprotective agent for the tert‐butyl carbamates of indoles, indazoles, carbazole, thiazoloindole, and pyrrole. The method is a mild one and is particularly expeditious for NH‐heteroarenes bearing electron‐withdrawing groups. 相似文献
226.
Recently, we have developed1 a new route for the stereo-specific introduction of an angular carboxyl or functionalized methyl groups2 in a rigid hydrophenanthrene moiety. The key step in this approach is a regioselective intramolecular α-keto carbenoid insertion across the benzylic C-H bond (at C-4a) in CuSO4-catalyzed thermal decomposition of the diazoketones and to the corresponding tetracyclic ketones and in moderate to good yields. A modified procedure3 of carbenoid decomposition of these diazoketones, in the presence of Cu2O under irradiation with tungsten filament lamp, improves the yields of the desired C-H insertion products. Thus, the ketones and have been prepared now in consistently higher yields (53-55%) from the pure diazoketones , m.p. 125-127°, and , m.p. 相似文献
227.
Nandini Nag Sutapa Ghosh Somenath Chakrabarty 《The European Physical Journal A - Hadrons and Nuclei》2010,45(1):99-110
We have investigated some of the properties of dense sub-nuclear matter at the crustal region (both the outer crust and the
inner crust region) of a magnetar. The relativistic version of the Thomas-Fermi (TF) model is used in the presence of a strong
quantizing magnetic field for the outer crust matter. The compressed matter in the outer crust, which is a crystal of metallic
iron, is replaced by a regular array of spherically symmetric Wigner-Seitz (WS) cells. In the inner crust region, a mixture
of iron and heavier neutron-rich nuclei along with electrons and free neutrons has been considered. Conventional Harrison-Wheeler
(HW) and Bethe-Baym-Pethick (BBP) equation of states are used for the nuclear mass formula. A lot of significant changes in
the characteristic properties of dense crustal matter, both at the outer crust and at the inner crust, have been observed. 相似文献
228.