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排序方式: 共有87条查询结果,搜索用时 15 毫秒
1.
Nagendranath Mahata V. Vishwanathan 《Journal of molecular catalysis. A, Chemical》1997,120(1-3):267-270
Kinetics of vapor phase hydrogenation of phenol to cyclohexanone over Pd/MgO system has been studied in a flow microreactor under normal atmospheric pressure. The reaction rate is found to be negative order with respect to the partial pressure of phenol and has increased from −0.5 to 0.5 with increasing temperature (473 to 563 K). The apparent activation energy (Ea) of the process is found to be close to 65 kJ per mol. On the basis of kinetic results a surface mechanism is proposed. 相似文献
2.
We obtain a solution of the DGLAP equation for the gluon at low x first by expanding the gluon in a Taylor series and then using the method of characteristics. We test its validity by comparing
it with that of Glück, Reya and Vogt. The convergence criteria of the approximation used are also discussed. We also calculate
εF
2(x,Q)2/ε In Q
2 using its approximate relations with the gluon distribution at low x. The predictions are then compared with the HERA data. 相似文献
3.
4.
5.
Mahata PK Venkatesh C Syam Kumar UK Ila H Junjappa H 《The Journal of organic chemistry》2003,68(10):3966-3975
A simple, highly efficient, and regioselective synthesis of functionalized quinolines through Vilsmeier cyclization of a variety of alpha-oxoketene-N,S-anilinoacetals has been reported. The cyclization is found to be facile with N,S-acetals bearing strongly activating groups on aniline, whereas yields of quinolines are moderate in other cases. The reaction could also be extended for the synthesis of substituted tricyclic benzo[h]quinoline, pyrido[2,3-h]quinoline, 4,7-diphenylphenanthroline, and tetracyclic quino[8,7-h]quinoline by performing a Vilsmeier reaction on N,S-acetals derived from 1-naphthylamine, m-phenylenediamine, o-phenylenediamine, and 1,5-diaminonaphthalene, respectively. A few of the newly synthesized quinolines are subjected to further transformation to afford 2-unsubstituted (Raney-Ni/Ethanol), quinoline-5,8-quinone (NBS/H(2)SO(4)), or 2-alkyl/aryl aminoquinolines through sequential m-CPBA oxidation to the corresponding (2-methylsulfonyl)quinoline followed by replacement with appropriate amines. Similarly, cycloannulation of a few 2-methylthio-3-benzoylquinolines with hydrazine hydrate under microwave irradiation afforded the corresponding substituted and fused pyrazolo[3,4-b]quinolines in excellent yields, whereas TBTH/AIBN-mediated cyclization of the corresponding 3-(2-bromobenzoyl)-2-methylthioquinolines yielded the corresponding benzothiopyrano-fused quinolines through radical translocation. 相似文献
6.
Tripathi V Navin A Mahata K Ramachandran K Chatterjee A Kailas S 《Physical review letters》2002,88(17):172701
Results for the cross section and average angular momentum for complete fusion at energies around the Coulomb barrier are presented for 7Li with 165Ho. Comparison of the cross sections with a one-dimensional barrier penetration model, using a potential consistent with the measured elastic scattering, showed a reduction above the barrier and an enhancement below it. An increase in the measured average angular momentum, , above the barrier and its consistency with that obtained from the fusion excitation function for weakly bound nuclei, is reported. These results together with a reanalysis of existing data conclusively demonstrate that the effect of breakup on fusion is coherent, like coupling to any nonelastic channel. 相似文献
7.
Background
Growth hormone (GH) plays an incompletely understood role in the development of the central nervous system (CNS). In this study, we use transgenic mice expressing a growth hormone antagonist (GHA) to explore the role of GH in regulating postnatal brain, spinal cord and body growth into adulthood. The GHA transgene encodes a protein that inhibits the binding of GH to its receptor, specifically antagonizing the trophic effects of endogenous GH. 相似文献8.
Overtone spectrum of o, m and p-nitrobenzaldehydes and p-chlorobenzaldehyde has been studied in 2000–12000 cm−1 region. Vibrational frequencies and anharmonicity constants for aryl as well as alkyl CH stretch vibrations have been determined.
We have also determined the internuclear distances for the aryl CH bond in the different molecules. The small variation observed
in these distances is an indication of the substitution effect.
It is observed that in the case of p-disubstituted benzens, the shift in aryl CH bond is proportional to sum of the Hammet σ of the substituents. However in the
case of o-disubstituted benzenes it is only 80% of the para-substituted shift. 相似文献
9.
Background
Organic light emitting devices (OLED) are becoming important and characterisation of them, in terms of structure, charge distribution, and intermolecular interactions, is important. Tris(8-hydroxyquinolinato)-aluminium(III), known as Alq3, an organomettalic complex has become a reference material of great importance in OLED. It is important to elucidate the structural details of Alq3 in its various isomeric and solvated forms. Solid-state nuclear magnetic resonance (NMR) is a useful tool for this which can also complement the information obtained with X-ray diffraction studies. 相似文献10.
Eder G Kloft S Martsinovich N Mahata K Schmittel M Heckl WM Lackinger M 《Langmuir : the ACS journal of surfaces and colloids》2011,27(22):13563-13571
The objective of this work is to study both the dynamics and mechanisms of guest incorporation into the pores of 2D supramolecular host networks at the liquid-solid interface. This was accomplished by adding molecular guests to prefabricated self-assembled porous monolayers and the simultaneous acquisition of scanning tunneling microscopy (STM) topographs. The incorporation of the same guest molecule (coronene) into two different host networks was compared, where the pores of the networks either featured a perfect geometric match with the guest (for trimesic acid host networks) or were substantially larger than the guest species (for benzenetribenzoic acid host networks). Even the moderate temporal resolution of standard STM experiments in combination with a novel injection system was sufficient to reveal clear differences in the incorporation dynamics in the two different host networks. Further experiments were aimed at identifying a possible solvent influence. The interpretation of the results is aided by molecular mechanics (MM) and molecular dynamics (MD) simulations. 相似文献