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排序方式: 共有403条查询结果,搜索用时 31 毫秒
41.
Panchangam Murali Krishna Katreddi Hussain Reddy Jay Prakash Pandey Dayananda Siddavattam 《Transition Metal Chemistry》2008,33(5):661-668
Binuclear copper(II) complexes of thiosemicarbazones derived from cuminaldehyde (p-isopropyl benzaldehyde) and substituted thiosemicarbazides NH2NHC(S)NHR, where R = H, Me, Et or Ph have been synthesized and characterized. The ESR indicates that the dissociation of dimeric
complex into mononuclear [Cu(L)Cl(DMSO)3] units in polar solvents like DMSO, where L = monoanionic thiosemicarbazone. The molecular ion peak in the LC-MS coincides
with the formula weight of the complexes. The absorption titration studies revealed that each of these complexes is an avid
binder to calf thymus-DNA. The apparent binding constants are in the order of 107–108 M−1. The nucleolytic cleavage activities of the ligands and their complexes were assayed on pUC18 plasmid DNA using gel electrophoresis
in the presence and absence of H2O2. The ligands showed increased nuclease activity when administered as copper complexes. All these copper(II) complexes behave
as an efficient chemical nucleases with hydrogen peroxide activation. These studies revealed that the complexes exhibit both
oxidative and hydrolytic chemistry in DNA cleavage. 相似文献
42.
B. Leela Maheswara Rao Shaik Nowshuddin Anjali Jha Murali K. Divi M. N. A. Rao 《合成通讯》2017,47(22):2127-2132
A new reagent, tert-butyl (2,4-dioxo-3-azaspiro [5,5] undecan-3-yl) carbonate (Boc-OASUD) for the preparation of N-Boc-amino acids is described. The Boc-OASUD reacts with amino acids and their esters at room temperature in the presence of a base and gives N-Boc-amino acids and their esters in good yields and purity. Introduction of the Boc group takes place without racemization. The Boc-OASUD, being a solid and more stable, is a better alternative to di-tert-butyl dicarbonate which is low melting and has to be dispensed in plastic containers than glass because of its poor stability. 相似文献
43.
M. G. Syed Basheer Ahamed V. S. Nagarethinam A. R. Balu A. Thayumanavan K. R. Murali C. Sanjeeviraja M. Jayachandran 《Crystal Research and Technology》2010,45(4):421-426
ZnSe films were deposited on glass substrates keeping the substrate temperatures, at room temperature (RT), 75, 150 and 250 °C. The films have exhibited cubic structure oriented along the (111) direction. Both the crystallinity and the grain size increased with increasing deposition temperature. A very high value of absorption co‐efficient (104 cm‐1) is observed. The band gap values decrease from a value of 2.94 eV to 2.69 eV with increasing substrate temperature. The average refractive index value is in the range of 2.39 – 2.41 for the films deposited at different substrate temperatures. The conductivity values increases continuously with temperature. Laser Raman spectra showed peaks at 140.8 cm‐1, 246.7 cm‐1and 204.5 cm‐1which are attributable to 2TA LO phonon and TO phonon respectively. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
44.
We perform atomistic simulations on the fracture behavior of two typical metallic glasses, one brittle (FeP) and the other ductile (CuZr), and show that brittle fracture in the FeP glass is governed by an intrinsic cavitation mechanism near crack tips in contrast to extensive shear banding in the ductile CuZr glass. We show that a high degree of atomic scale spatial fluctuations in the local properties is the main reason for the observed cavitation behavior in the brittle metallic glass. Our study corroborates with recent experimental observations of nanoscale cavity nucleation found on the brittle fracture surfaces of metallic glasses and provides important insights into the root cause of the ductile versus brittle behavior in such materials. 相似文献
45.
Kamsali Murali Mohan Achari Chinnasamy Ramaraj Ramanathan 《Tetrahedron: Asymmetry》2017,28(6):830-836
A conformationally rigid chiral molecule LB-I with Lewis basic site has been designed and synthesized in racemic form from ferrocene via Lewis acid mediated diastereoselective cyclization of hydroxy lactam. Both isomers were successfully obtained in enantiomerically pure form through classical resolution using dibenzoyl-d-tartaric acid as the chiral resolving agent in acetone. The nature of the diastereomeric salt formed in the resolution process was investigated by single crystal X-ray crystallographic studies. The absolute configuration of (+)-LB-I was unambiguously assigned as (S,Rp) by single crystal analysis of the salt I obtained from precipitate fraction containing (+)-LB-I and dibenzoyl-d-tartaric acid. 相似文献
46.
47.
Samanta D Sankar RM Jaisankar SN Alam MS Mandal AB 《Chemical communications (Cambridge, England)》2011,47(43):11975-11977
A simple and convenient method to prepare acid-responsive microcapsules by using functionalized single-walled carbon nanotubes and ytterbium triflate has been developed. Fluorescence active compounds were "pre-loaded" or "post-loaded" in the microcapsules and released later in acidic medium. An interesting "zip-unzip" phenomenon was observed while filming the action of acid on microcapsules under a microscope. 相似文献
48.
Photoactive hyperbranched benzylidene liquid‐crystalline polyester (PAHBP) and photoactive linear benzylidene liquid‐crystalline polyester (PALBP) were synthesized by solution polycondensation with pyridine as an acid acceptor. PAHBP and PALBP were thoroughly characterized with Fourier transform infrared, 1H and 13C NMR, ultraviolet–visible spectrophotometry, fluorescent spectrophotometry, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, and polarized optical microscopy. Both polymers exhibited nematic mesophase. The glass‐transition temperature and liquid‐crystalline isotropic temperature of PAHBP were higher than those of PALBP. During photolysis under ultraviolet light, both polymers underwent an intermolecular photocycloaddition reaction, and the photoactivity of PAHBP was faster than that of PALBP; this was further confirmed by photoviscosity studies. PALBP and PAHBP were fluorescent in nature. An increase in the fluorescence intensity with the time of ultraviolet‐light irradiation was observed for both PAHBP and PALBP. The rate of increase in the fluorescence intensity of the linear analogue (PALBP) was higher than that of the hyperbranched polymer (PAHBP). This behavior could be attributed to the attainment of better planarity in the case of the linear one but not in the case of PAHBP because of the rapid crosslinking of PAHBP leading to an irregular architecture. This behavior was further confirmed by the calculation of the steric energy from corresponding model compounds. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3986–3994, 2006 相似文献
49.
Spectral and temporal measurements undertaken on a single picosecond laser pulse from a flash lamp pumped, cavity dumped, active/passive mode-locked Nd:YAG laser are presented in this paper. Optimization of several parameters of the resonator cavity produced a single pulse with 0.7 mJ energy and 102 contrast. The pulse duration was variable from 24 to 120 ps by using intra-cavity etalons of different thicknesses. The pulse width and spectrum of the pulse were simultaneously measured using a second harmonic autocorrelator and a spectrometer. The time bandwidth product was 0.445, which is close to theoretical limit for a bandwidth limited pulse. 相似文献
50.
Two methods for symmetrizing Markov processes are discussed. Letu
a(x, y) be the potential density of a Lévy process on a compact Abelian groupG. A general condition is given that guarantees thatv(x, y)=ua(x, y)+ua(y, x) is the potential density of a symmetric Lévy process onG. The second method arises by considering the linear space of one-potentialsU
1
f, withf inL
2, endowed with the inner product (U
1
f,U
1
g)=fU
1
g+gU
1
f. If the semigroup ofX(t) is normal, then the completionH of this space is the Dirichlet space of a symmetric processY(t). A set that is semipolar forX(t) is polar forY(t). 相似文献