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71.
Latha G. Nair Stephane Bogen Frank Bennett Kevin Chen Bancha Vibulbhan Yuhua Huang Weing Yang Ronald J. Doll N.-Y. Shih F. George Njoroge 《Tetrahedron letters》2010,51(23):3057-3061
The Hepatitis C Virus (HCV) is a major health hazard and its infection is a leading cause of chronic liver disease world wide. In our efforts toward the discovery of a back up to our first clinical candidate, Boceprevir (SCH 503034), we approached the depeptidization of the molecule through macrocyclization. Herein we report the design and synthesis of fluoro amino acids with desired stereochemistry required for the synthesis of macrocyclic inhibitors with fluorine at various positions of the aliphatic chain. Biological activities of representative examples are also reported. 相似文献
72.
73.
Park YS Whalley AC Kamenetska M Steigerwald ML Hybertsen MS Nuckolls C Venkataraman L 《Journal of the American Chemical Society》2007,129(51):15768-15769
We compare the low bias conductance of a series of alkanes terminated on their ends with dimethyl phosphines, methyl sulfides, and amines and find that junctions formed with dimethyl phosphine terminated alkanes have the highest conductance. We see unambiguous conductance signatures with these link groups, indicating that the binding is well-defined and electronically selective. This allows a detailed analysis of the single-molecule junction elongation properties which correlate well with calculations based on density functional theory. 相似文献
74.
75.
Let G = (V, E) be a connected graph. A set D ? V is a set-dominating set (sd-set) if for every set T ? V ? D, there exists a nonempty set S ? D such that the subgraph 〈S ∪ T〉 induced by S ∪ T is connected. The set-domination number γs(G) of G is the minimum cardinality of a sd-set. In this paper we develop properties of this new parameter and relate it to some other known domination parameters. 相似文献
76.
Shilpa M Nagababu P Kumar YP Latha JN Reddy MR Karthikeyan KS Gabra NM Satyanarayana S 《Journal of fluorescence》2011,21(3):1155-1164
Three symmetric ligands 7-methyl dipyrido-[3,2-a;2′,3′-c]phenazine (dppz-CH3), 7-nitro dipyrido-[3,2-a;2′,3′-c]phenazine (dppz-NO2) and benzo[i]dipyrido-[3,2-a;2′,3′-c]phenazine (dppn) and their ruthenium(II) complexes [Ru(en)2(L)][ClO4]2 (en= ethylenediamine), L= dppz-CH3, dppz-NO2 and dppn have been synthesized and characterized by IR, 1H, 13C NMR and Mass spectra. The interactions of these complexes with calf thymus DNA have been investigated by spectrophotometric,
spectrofluorimetric, circular dichroism, viscosity and thermal denaturation studies. As the planar extension of the intercalative
ligand increases, the interaction of the complex with DNA increases, indicating that the size and shape of the intercalalative
ligand has a marked effect on the strength of interaction. The plot of log K versus log [Na+] yield a slope of -1.26, -1.53, -1.60 for the complexes 1, 2 and 3 respectively. These three complexes have been found to
promote the cleavage of plasmid pBR 322 DNA upon irradiation. 相似文献
77.
Minh-Phuong TRAN Thanh-Nhan NGUYEN Phuoc-Toan HUYNH Nhu-Binh LY Minh-Dang NGUYEN Quoc-Anh HO 《数学物理学报(B辑英文版)》2022,(1):105-126
In this paper,we establish a new algorithm to the non-overlapping Schwarz domain decomposition methods with changing transmission conditions for solving one dimensional advection reaction diffusion problem.More precisely,we first describe the new algorithm and prove the convergence results under several natural assumptions on the sequences of parameters which determine the transmission conditions.Then we give a simple method to estimate the new value of parameters in each iteration.The interesti... 相似文献
78.
Temperature and frequency dependence of dielectric constant and conductivity properties of Pb0.77K0.26Li0.2Ti0.25Nb1.8O6 (PKLTN) ceramics are modelled through the universal dielectric response (UDR). Partial substitution of Ti4+ for Nb5+ was compensated by charge and the creation of oxygen vacancies according to the Kroger-Vink notation. The electrons released by this reaction are captured by Nb5+ and Ti4+ to generate Nb3+ and/or Ti3+. The hopping of electrons between Nb5+–Nb3+ and Ti4+–Ti3+ are believed to participate in conductivity. Characterization of the dielectric constant has been performed from room temperature to 590°C in the frequency range from 45 Hz to 5 MHz. The measured dielectric constant obeyed Jonscher's dielectric dispersion relations: ε l = ε ∞ + sin(n(T)π/2)(a(T)/ε 0)(ωn ( T )?1) and ε ll = σ/iε 0 ω + cos(n(T)π/2)(a(T)/ε 0)(ωn ( T )?1). Cole-Cole plots inclined at an angle (1 ? n(T))π/2 and followed the trend of universal material behavior ε ∞ + A(T)(ωn ( T )?1). The exponent n(T) and coefficient A(T) = (a(T)S/L) exhibited a minimum and maximum at T c = 425°C, respectively. The conductivity studies show the contribution of the hopping of bound charge carriers to conduction in PKLTN. 相似文献
79.
Gearheart LA Somoza MM Rivers WE Murphy CJ Coleman RS Berg MA 《Journal of the American Chemical Society》2003,125(39):11812-11813
The nature of the counterion is shown to have a pronounced effect on the apparent dynamic polarity in the interior of DNA. Time-resolved Stokes-shift measurements in the 80 ps to 40 ns time range were made on a polarity-sensitive fluorophore (coumarin 102) that replaces a base pair in an oligonucleotide. With sodium counterions, the emission spectrum narrows with time, whereas with tetrabutylammonium counterions, it does not. Our interpretation is that a subpopulation of helices have sodium cations bound in a fashion that slows the normal dynamics. 相似文献
80.
K.Madhavi Latha 《Journal of Quantitative Spectroscopy & Radiative Transfer》2004,84(2):207-213
EP/TOMS satellite-derived aerosol index (AI) data have been analyzed over typical tropical urban environment corresponding to Hyderabad, India to study seasonal and annual distribution of UV-absorbing aerosols. Observations reveal that UV-absorbing aerosol loading is highly seasonal. During the years 1987, 1991 and 1992 high concentration of UV-absorbing aerosols into the atmosphere over Hyderabad region has been observed. UV-absorbing aerosols are high during summer period. Ground-based measurements of aerosol optical depth (AOD) and satellite-derived AI showed good correlation with AOD at . 相似文献