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101.
102.
Random links between otherwise distant nodes can greatly facilitate the propagation of disease or information, provided contagion can be transmitted by a single active node. However, we show that when the propagation requires simultaneous exposure to multiple sources of activation, called complex propagation, the effect of random links can be just the opposite; it can make the propagation more difficult to achieve. We numerically calculate critical points for a threshold model using several classes of complex networks, including an empirical social network. We also provide an estimation of the critical values in terms of vulnerable nodes. 相似文献
103.
The reaction of isatoic anhydrides with potassium cyanide is described. The stoichiometry of the reactants and reaction times dictate the formation of either 2-imino-3-indolinones or spiro[indoline-2,2′(1′H)quinazolines]. Some spectral data is also discussed. 相似文献
104.
David E. Chavez Jeffery C. Bottaro Mark Petrie Damon A. Parrish 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(44):13165-13167
This study presents the synthesis and characterization of a fused, tricyclic 1,2,3,4‐tetrazine ring system. The molecule is synthesized in a three‐step process from 5,5′‐dinitro‐bis,1,2,4‐triazole via a di‐N‐amino compound. Oxidation to form the azo‐coupled fused tricyclic 1,2,3,4‐tetrazine is achieved using tert‐butyl hypochlorite as the oxidant. The di‐N‐amino compound and the desired fused tricyclic 1,2,3,4‐triazine display interesting thermal behavior and are predicted to be high‐performance energetic materials. 相似文献
105.
Dr. Yongxing Tang Dr. Lauren A. Mitchell Dr. Gregory H. Imler Dr. Damon A. Parrish Prof. Dr. Jean'ne M. Shreeve 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5988-5992
3,5-Dinitrimino-1,2,4-triazole ( 2 ) with three protons has the potential of deprotonation to form energetic salts. Neutralization of 2 with 50 % hydroxylamine in varying molar ratios leads to the formation of the corresponding mono/dihydroxylammonium energetic salts. Additionally compound 5 , an ammonia oxide adduct of dihydroxylammonium 3,5-dinitramino-1,2,4-triazolate, was prepared when excess hydroxylamine was used. The structures of 3 – 5 are supported by single-crystal X-ray diffraction. The energetic properties of the new materials are competitive. Utilization of ammonia oxide adducts in hydroxylammonium energetic salts could lead to future practical applications as energetic materials. 相似文献
106.
Reddy Damavarapu Rao Surapaneni Raja Duddu Farhad Farhor Paritosh Dave Damon Parrish 《Journal of heterocyclic chemistry》2007,44(1):241-244
107.
Synthetic or natural aza-sugars have shown promise as a therapeutic approach to a variety of disease states by acting as transition state mimics to sugar processing enzymes. Although the synthesis of functionalized bicyclo[3.2.1]octanes has been reported, the procedures are relatively long and low yielding. Herein, we report the facile synthesis of polyhydroxylated 2-azabicyclo[3.2.1]octane that can be selectively functionalized. 相似文献
108.
Comin MJ Agbaria R Ben-Kasus T Huleihel M Liao C Sun G Nicklaus MC Deschamps JR Parrish DA Marquez VE 《Journal of the American Chemical Society》2007,129(19):6216-6222
The replacement of the furanose ring by a cyclopentane in nucleosides generates a group of analogues known generically as carbocyclic nucleosides. These compounds have increased chemical and enzymatic stability due to the absence of a true glycosyl bond that characterizes conventional nucleosides. The additional fusion of a cyclopropane ring to the cyclopentane produces a bicyclo[3.1.0]hexane system that depending on its location relative to the nucleobase is able to lock the embedded cyclopentane ring into conformations that mimic the typical north and south conformations of the furanose ring in conventional nucleosides. These bicyclo[3.1.0]hexane templates have already provided important clues to differentiate the contrasting conformational preferences between kinases and polymerases. Herein, we describe the design, synthesis, and phosphorylation pattern of a new bicyclo[3.1.0]hexane thymidine analogue that seems to possess an ideal spatial distribution of pharmacophores for an optimal interaction with herpes simplex 1 thymidine kinase. The bicyclo[3.1.0]hexane template represents a privileged rigid template for sculpting other carbocyclic nucleosides to meet the demands of specific receptors. 相似文献
109.
[reaction: see text] A palladium-catalyzed domino sequence was developed to rapidly construct the core structure of neosarpagine and other quinuclidine-related alkaloids. The cyclization of ketone 11 to ethylidene 4 with Pd(dba)2, DPEphos, LiHMDS, and ZnCl2 in THF represents a new domino process wherein a nonstabilized enolate served as a nucleophile. 相似文献
110.
The output of a switch,or, effective bandwidths for networks 总被引:1,自引:0,他引:1
Consider a switch which queues traffic from many independent input flows. We show that in the large deviations limiting regime
in which the number of inputs increases and the service rate and buffer size are increased in proportion, the statistical
characteristics of a flow are essentially unchanged by passage through the switch. This significantly simplifies the analysis
of networks of switches. It means that each traffic flow in a network can be assigned an effective bandwidth, independent
of the other flows, and the behaviour of any switch in the network depends only on the effective bandwidths of the flows using
it.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献