199 research outputs found
New reactions and strategies in divergent syntheses of macrolide antibiotics
No full textFrom the microbial world, antibiotics are structurally complex and highly potent chemical weapons that co-evolved with bacteria. Macrolide (glycosylated cyclic polyketides) antibiotics have been used extensively as first-line antibacterial agents since the discovery of the broad-spectrum antibiotic erythromycin A in 1952. However wide-spread use of antibiotics has led pathogens to develop drug resistance. Therefore new and enhanced antibiotics are constantly in need. Described in this dissertation is my effort to emulate the synthetic capabilities of erythromycin-producing bacteria by accessing novel erythromycin-inspired polyketides via divergent total synthesis. New allene oxidation methods have been developed and implemented in a modular and divergent route to produce a diversified portfolio of cyclic polyketides and their glycoconjugates. I will disclose a total synthesis of 4,10-didesmethyl-(9S)-dihydroerythronolide A (Chapter 2), preparation of glycosylated erythromycin analogs (Chapter 3) and progress towards synthesis of 9(S)-dihydroerythronolide A (Chapter 4).Ph.D.Includes bibliographical referencesby Libing Y
Research on the relationship between the elements and pharmacological activities in velvet antler using factor analysis and cluster analysis
No full textNovel prognostic models for osteosarcoma: The potential of long-chain acyl-coenzyme A synthases
No full textInvestigation of the Temperature Character of IGBT Solder Delamination Based the 3-D Thermal-Electro Coupling FEM
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Systematic Thinking of Human Intelligence
No full textThis paper expounds the great significance of human intelligence research from the height of the wisdom age. We should understand what it is to be a human being and what are the mechanisms of this intelligence. The author advocates that systematic science should be involved in such research. Methodology, especially oriental holistic thinking, is important. We put out the idea of “Education Engineer”, first try to do theoretical research, focus a concept System Quotient, then to build a model. To establish such a system, we undertake several decades of exploration according to the thought of Xuesen Qian’s “Dacheng Wisdom” and the fruits of information science and intelligence science. The concepts of “Human intelligence system” and “System Quotient ”(SQ) are proposed, developed completely and applied in the classroom. A “teaching information feedback system” has been created. It contains a “classroom informatization” and a “Playing with Science” system
ON GEODESICS OF FINSLER METRICS VIA NAVIGATION PROBLEM
No full textThis paper is devoted to a study of geodesics of Finsler metrics via Zermelo navigation. We give a geometric description of the geodesics of the Finsler metric produced from any Finsler metric and any homothetic field in terms of navigation representation, generalizing a result previously only known in the case of Randers metrics with constant S-curvature. As its application, we present explicitly the geodesics of the Funk metric on a strongly convex domain.Mathematics, AppliedMathematicsSCI(E)0ARTICLE83015-302413
Thermal distribution measurement upon micro-resistance lines using Thermoreflectance technique
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PCB Network Analysis for Circuit Partitioning
No full textThe complexity of automatic placement and routing is proportional to the scale of the circuit. Through netlist partition algorithms, printed circuit board (PCB) circuits are divided into different submodules, and the problem scale is effectively reduced in order to obtain the optimal automatic layout and routing. In this paper, we analyze net attributes and potential patterns in netlists through visualization, and propose a heuristic PCB netlist partition approach based on net attributes and potential patterns which we discover from netlists. Our partition approach takes the netlist as input, and module partition set as output. Firstly, the modules are prepartitioned using net attributes. Further, the special patterns in circuits are discovered, and the scattered resistors, capacitors, and other components caused by prepartitioning would be allocated to initial modules by three rules—classifying, matching, and force strategy. Our method is evaluated on 11 PCB netlists which are built manually. Experimental results show that our proposed netlist partition approach significantly outperforms the state of the art on all evaluation indices, which can achieve 80–96% partition accuracy
On Finsler surfaces of constant curvature with two-dimensional isometry group
No full textIn this paper, we study Finsler surfaces of constant (flag) curvature. We show that the space of those, with two-dimensional isometric group depends on two arbitrary constants. We also give a new technique to recover Finsler metrics from the specified two constants. Using this technique we obtain some new Finsler surfaces of constant flag curvature with two-dimensional isometry group.National Natural Science Foundation of China [11371032, 11301283]SCI(E)[email protected]; [email protected]
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