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排序方式: 共有238条查询结果,搜索用时 203 毫秒
61.
62.
Liu Y Kravtsov V Walsh RD Poddar P Srikanth H Eddaoudi M 《Chemical communications (Cambridge, England)》2004,(24):2806-2807
A novel anionic metal-organic cube (MOC-1), [Ni(8)(HImDC)(12)](8-), has been synthesized by metal-ligand directed assembly of eight tri-connected Ni nodes and twelve doubly deprotonated bis(bidentate) imidazoledicarboxylic acid ligands (HImDC). 相似文献
63.
64.
Golam Mohiuddin Sharmistha Ghosh Nazma Begum Somen Debnath Srikanth Turlapati Doddamane Sreenivasamurthy Shankar Rao 《Liquid crystals》2018,45(10):1549-1566
Here, we report the first examples of achiral unsymmetrical three-ring bent-shaped liquid crystals comprising amide and imine linkages with transverse substituents of methyl and chloro moieties on the central phenyl ring in the core, exhibiting polar banana phases. The extensive intra and inter molecular H-bonding induced novel banana mesomorphic phases. One-dimensional stacking in the mesomorphic phase as well as ferroelectric polar order promoted by intermolecular H-bonding of amide linkage is demonstrated. The compounds exhibit multifunctional properties viz., the enantiotropic liquid crystalline (LC) phase at ambient temperatures, electro-optical response, spontaneous polarisation, emission characteristics with large Stokes shift, and even charge distribution with large voltage holding ratio (VHR) values. The smectic type phase was confirmed by XRD studies and polar order was established by switching current and dielectric investigations. DFT studies revealed the importance of their suitability for display applications. 相似文献
65.
Singularly perturbed elliptic equations with superlinear nonlinearities of polynomial type are considered on an annulus in Rn, n≥4. It is shown that for small parameters there exist solutions which concentrate on manifolds of dimensions one, three and seven, which are given as Hopf-fibres. 相似文献
66.
We show that any general semilinear elliptic problem with Dirichlet or Neumann boundary conditions in an annulus A⊆R2m, m?2, invariant by the action of a certain symmetry group can be reduced to a nonhomogeneous similar problem in an annulus D⊂Rm+1, invariant by another related symmetry. We apply this result to prove the existence of positive and sign changing solutions of a singularly perturbed elliptic problem in A which concentrate on one or two (m−1) dimensional spheres. We also prove that the Morse indices of these solutions tend to infinity as the parameter of concentration tends to infinity. 相似文献
67.
Srikanth S. Kamath 《Journal of Dispersion Science and Technology》2013,34(9):1304-1310
A spray drying technique was applied to prepare composite microparticles of a water-insoluble herbicide, atrazine(AT) and a water-soluble herbicide 2,4-dichloro phenoxy acetic acid (2,4-D) for the purpose of improving the water solubility of AT. A homogenous mixture of an ethanol solution of AT and an aqueous 2,4-D solution at different ratios were spray dried using a laboratory scale spray drier. Quantitative elemental analysis suggested that the AT/2,4-D ratio in each composite microparticle was nearly the same as the desired formulation ratio. The resulting samples were characterized by powder x-ray diffractometry (XRD), differential scanning calorimetry (DSC), Fourier transform infra red (FT-IR) and scanning electron microscopy (SEM). It was found that the crystallinity of AT and 2,4-D were maintained in the composite particles. Moreover, the release of AT from dissolved composite microparticles was markedly improved because of an increase in the effective surface area following rapid dissolution of 2, 4 D. Hence, this study shows that it is possible to prepare AT-2,4-D composite microparticles using a laboratory scale spray drier and that this can improve the ability of AT to dissolve in water. 相似文献
68.
K. V. Nagalakshmi M. Padma P. Shyamala V. Srikanth A. Satyanarayana P. V. SubbaRao 《Transition Metal Chemistry》2013,38(5):523-527
The kinetics of dissociation of bis(2,4,6–tripyridyl-s-triazine) iron(II), ([Fe(TPTZ)2]2+) has been studied in CTAB/chloroform/hexane reverse micellar medium. In the absence of acid, the reaction is immeasurably slow and does not go to completion in conventional aqueous medium but is markedly accelerated and takes place with a rate constant equal to 55.3 × 10?3 s?1 and goes to completion in reverse micelles. The significant increase in rate is attributed to the special properties of the water pool in the reverse micelles like low dielectric constant, nucleophilic effect of Br- ion, and favorable partitioning of TPTZ in the organic phase. The rate of the reaction decreases with increase in W (=[H2O]/[CTAB]) at constant CTAB concentration and remains constant with increase in CTAB at fixed W. The results are compared with other closely related systems. 相似文献
69.
H. Srikanth A.K. Raychaudhuri C.R. Venkateswara Rao P. Ramasamy Hemantkumar N. Aiyer C.N.R. Rao 《Physica C: Superconductivity and its Applications》1992,200(3-4):372-376
Tunneling studies have been carried out on single crystals of Bi2Ca1−xSrxCu2O8+δ over a wide range of compositions wherein the hole concentration varies by a factor of 2.5. The 2Δ value varies between 25 meV and 75 meV over the composition range studied, but scales with 2Δ/kBTc≈9.5 throughout. 相似文献
70.
Luchezar L. Avramov Ragnar-Olaf Buchweitz Srikanth Iyengar 《Inventiones Mathematicae》2007,169(1):1-35
A differential module is a module equipped with a square-zero endomorphism. This structure underpins complexes of modules
over rings, as well as differential graded modules over graded rings. We establish lower bounds on the class – a substitute
for the length of a free complex – and on the rank of a differential module in terms of invariants of its homology. These
results specialize to basic theorems in commutative algebra and algebraic topology. One instance is a common generalization
of the equicharacteristic case of the New Intersection Theorem of Hochster, Peskine, P. Roberts, and Szpiro, concerning complexes
over commutative noetherian rings, and of a theorem of G. Carlsson on differential graded modules over graded polynomial rings. 相似文献