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51.
Mirela Damian-Iordache Sriram V. Pemmaraju 《Journal of Algorithms in Cognition, Informatics and Logic》2002,42(2):255
The main result of this paper is a (2 + )-approximation scheme for the minimum dominating set problem on circle graphs. We first present an O(n2) time 8-approximation algorithm for this problem and then extend it to an
time (2 + )-approximation scheme for this problem. Here n and m are the number of vertices and the number of edges of the circle graph. We then present simple modifications to this algorithm that yield (3 + )-approximation schemes for the minimum connected and the minimum total dominating set problems on circle graphs. Keil (1993, Discrete Appl. Math.42, 51–63) shows that these problems are NP-complete for circle graphs and leaves open the problem of devising approximation algorithms for them. These are the first O(1)-approximation algorithms for domination problems on circle graphs. 相似文献
52.
The cyclization of an aryllithium tethered to a methylenecycloalkane, generated from 2-(o-bromobenzyl)-1-methylenecycloalkanes 1, 2, and 3 by low-temperature lithium-bromine exchange, has been found to be a kinetically slow but thermodynamically favorable process that proceeds at a convenient rate in an exclusively 5-exo fashion when solutions of the aryllithium in n-heptane-di-n-butyl ether (9:1 v/v) are warmed to 45 degrees C. The cyclization affords stereoisomerically pure cis-fused products (7 and 8) when the methylenecycloalkane is five- or six-membered but it is less stereoselective when the methylenecycloalkane is seven-membered. The ring-closure of the aryllithium derived from 2-(o-bromobenzyl)-1-methylenecyclohexane (2) provides an experimentally convenient route to stereoisomerically pure 4a-substituted cis-hexahydrofluorenes in 60-90% isolated yield. 相似文献
53.
The crystal structures of (i) CH3(C9H6O2)SO2C6H5 and (ii) CH3(C8H8O2)SO2?C6H5 have been determined by X-ray diffraction. (i) crystallizes in the monoclinic space groupP21/c with unit cell parametersa=8.814(1)Å,b=10.310(1)Å,c=15.841(4)Å, β=98.17(1)o, andZ=4, and (ii) crystallizes in the orthorhombic space groupP212121 with unit cell parametersa=6.206(1)Å,b=11.752(5)Å,c=19.865(3)Å, andZ=4. The pyran ring in both of them is in the distorted half-chair conformation with differeing degrees of distortion from the ideal. 相似文献
54.
Daniel E. Bakken Sriram V. Narasimhan Karen J.L. Burg Bruce Z. Gao 《Macromolecular Symposia》2005,227(1):335-344
250,000 Americans suffer from spinal cord injury caused by vehicular, work, and sports related accidents[1]. After injury to the spinal cord, axons do not have the capability of regenerating across the lesioned site. To understand the mechanisms of axon regeneration and to identify a better method of regeneration, a new technique for mimicking and studying the in vivo cellular environment is needed. To meet this goal, we have developed a laser cell micropatterning system that uses a weakly focused laser beam to pattern both biological cells and nonbiological particles for the study of various cell-cell-polymer interactions. Using this system, we have successfully copatterned neurons, glial cells, and polymer microspheres into a viable matrix. These copatterns allow us to study the effects nerve growth factor has, when released from a degradable polymer microsphere, on a single neuron within a specific arrangement of multiple cell types. 相似文献
55.
Motivated by recent observations of rheochaos in sheared wormlike micelles, we study the coupled nonlinear partial differential equations for the hydrodynamic velocity and order-parameter fields in a sheared nematogenic fluid. In a suitable parameter range, we find irregular, dynamic shear banding and establish by decisive numerical tests that the chaos we observe in the model is spatiotemporal in nature. 相似文献
56.
57.
Progress in the research of artemisinin and its analogues as antimalarials: an update 总被引:3,自引:0,他引:3
Malaria is the number one infectious disease in the world today. Worldwide, over two million people die each year from malaria. This shocking reality is largely due to the emergence of drug resistant strains of Plasmodium falciparum. Artemisinin, a sesquiterpene lactone endoperoxide isolated from Artemesia annua has been shown to be a fast acting, safe and effective drug against multidrug-resistant and sensitive strains of P. falciparum. This article reports a survey of the literature dealing with artemisinin related antimalarial issues that have appeared from 1980s to the beginning of 2003. A broad range of medical and pharmaceutical disciplines is covered, including a brief introduction about discovery, phytochemical aspects, antimalarial mechanism of action, pharmacokinetics, and major drawbacks and various structural modifications made to overcome them. 相似文献
58.
Dongamanti Ashok Aamate Vikas Kumar Devulapally Mohan Gandhi Gundu Srinivas Balabadra Saikrishna Manga Vijjulatha Yogeeswari Perumal Sriram Dharmarajan Balasubramanian Sridhar 《Molecular diversity》2017,21(4):999-1010
Molecular Diversity - On the basis of reported antimycobacterial property of chroman-4-one pharmacophore, a series of chemically modified bis-spirochromanones were synthesized starting from... 相似文献
59.
Development and validation of an RP‐HPLC method for the quantitation of odanacatib in rat and human plasma and its application to a pharmacokinetic study
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Anitha Police Sandip Gurav Vinay Dhiman Mohd Zainuddin Ravi kanth Bhamidipati Sriram Rajagopal Ramesh Mullangi 《Biomedical chromatography : BMC》2015,29(11):1664-1669
A simple, specific, sensitive and reproducible high‐performance liquid chromatography (HPLC) assay method has been developed and validated for the estimation of odanacatib in rat and human plasma. The bioanalytical procedure involves extraction of odanacatib and itraconazole (internal standard, IS) from a 200 μL plasma aliquot with simple liquid–liquid extraction process. Chromatographic separation was achieved on a Symmetry Shield RP18 using an isocratic mobile phase at a flow rate of 0.7 mL/min. The UV detection wave length was 268 nm. Odanacatib and IS eluted at 5.5 and 8.6 min, respectively with a total run time of 10 min. Method validation was performed as per US Food and Drug Administration guidelines and the results met the acceptance criteria. The calibration curve was linear over a concentration range of 50.9–2037 ng/mL (r2 = 0.994). The intra‐ and inter‐day precisions were in the range of 2.06–5.11 and 5.84–13.1%, respectively, in rat plasma and 2.38–7.90 and 6.39–10.2%, respectively, in human plasma. The validated HPLC method was successfully applied to a pharmacokinetic study in rats. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
60.
B. T. Ramanjaneyulu Virsinha Reddy Panjab Arde Sriram Mahesh Dr. R. Vijaya Anand 《化学:亚洲杂志》2013,8(7):1489-1496
A combination of the oxidative N‐heterocyclic carbene catalysis and click chemistry has been explored for the direct, one‐pot synthesis of 1,2,3‐triazole derivatives from aromatic aldehydes. This procedure was found to be very efficient and a variety of 1,2,3‐triazole derivatives could be accessed through their corresponding propargyl esters in moderate‐to‐good yields under mild conditions. 相似文献