Chemical structure

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  • Mapping and classification of chemical compound names are important aspects of the tasks of BioNLP. This paper introduces the architecture of a system for the syntactic and semantic analysis of such names. Our system aims at yielding both the denoted chemical structure and a classification of a given name. We employ a novel approach to the task which promises an elegant and efficient way of solving the problem. The proposed system differs significantly from existing systems, in that it is also able to deal with underspecifying names and class names. ...

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  • Glycosphingolipids (GSLs) were purified from adults and plerocercoids of the tapeworm Diphyllobothrium hottai, and their chemical structures were determined. Total lipid fractions prepared from chloroform/methanol extracts of whole tissues were fractionated successively on ion-exchange chromatography, silicic acid column chromatography, and preparative TLC. The purified GSLs were characterized by methylation analysis, TLC-immunostaining, liquid secondary ion MS, MALDI-TOF MS, and 1H-NMR.

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  • The chemical structure of a novel lipid A, the major com-ponent of the lipopolysaccharide from the marine gamma-proteobacteriumMarinomonas vagaATCC 27119 T ,was determined by compositional analysis, NMR spectroscopy, and MS.

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  • We describe the semantic enrichment of journal articles with chemical structures and biomedical ontology terms using Oscar, a program for chemical named entity recognition (NER). We describe how Oscar works and how it can been adapted for general NER. We discuss its implementation in a real publishing workflow and possible applications for enriched articles.

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  • From the lipopolysaccharide of the deep rough mutant I-69 Rd–/b+ of Haemophilus influenzae two oligosaccharides were obtained after de-O-acylation and separation by high-performance anion exchange chromatography. Their chemical structures were determined by one- and two-dimensional 1H-, 13C- and 31P-NMR spectroscopy as aKdo-4P-(2 fi 6)-bGlcN-4P-(1 fi 6)-aGlcN-1P and aKdo-5P-(2 fi 6)-bGlcN-4P-(1 fi 6)-aGlcN-1P.

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  • The chemical structure of the phosphorylated carbohydrate backbone of the lipopolysaccharide (LPS) fromAcineto-bacter baumanniistrain ATCC 19606 was investigated by chemical analysis and NMR spectroscopy of oligosaccha-rides obtained after deacylation or mild acid hydrolysis. Fromthe combined information the following carbohydrate backbones can be deduced

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  • From the root of Calotropis gigantea, six compounds were isolated: 12-O-benzoyllineolon (1), 12-O-benzoyldeacetylmetaplexigenin (2), calotropone (3), 2,3-dimethoxyphenol (4), 2,5- dimethoxyphenol (5), 2-formyl-5-hydroxymethylfuran (6). The chemical structure of these compounds were elucidated by their NMR spectra and comparison with references.

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  • Polymers are materials of very high molecular weight that are found to have multifarious applications in our modern society. They usually consist of several structural units bound together by covalent bonds [1,2]. For example, polyethy- lene is a long-chain polymer and is represented by

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  • Enzymes are proteins that catalyze chemical reactions. A protein is simply a polypeptide composed of amino acids linked by a peptide bond, and the term generally, but not always, refers to the folded conformation. To understand how an enzyme functions, including its binding and functional properties, it is necessary to know the properties of the amino acids and how the amino acids are linked together, including the torsion angles of the bonds and the space occupied, and the interactions of the atoms leading to the final conformations of the folded protein.

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  • Comprehensive manual embracing essentially all the classical and modern areas of chemical kinetics. Provides details of modern applications in chemistry, technology and biochemistry. Special sections of the book treat subjects not covered sufficiently in other manuals, including: modern methods of experimental determination of rate constants of reactions including laser pico- and femtochemistry, magnetochemistry, and ESR; and descriptions of advanced theories of elementary chemical processes.

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  • The chemical sensor plays an essential role in the fields of environmental conservation and monitoring, disaster and disease prevention, and industrial analysis. A typical chemical sensor is a device that transforms chemical information in a selective and reversible way, ranging from the concentration of a specific sample component to total composition analysis, into an analytically useful signal.

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  • Two of the main distinctions between chemical engineers and other engineering disciplines are the topics of mass and energy balances. Within these two topics there are a lot of underlying chemical principles that help chemical engineers to perform calculations to determine what is happening in a system, allowing better control of a process.

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  • Chemical substances (also called pure substances) may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook.[2] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties.[3] The chemical substance index published by CAS also includes several alloys of uncertain composition.

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  • Chemicals are able to bring about both desirable and undesirable effects on organisms to which they are exposed, and the actions of medicines and poisons and toxic agents have been recognized for thousands of years. As a result of industrialization, modern man and the environment is now exposed to increasing numbers of chemicals. Because of their potential hazard, there is an appreciation of the requirement to assess the effects of these chemicals. Since chemical structure was elucidated (for a very brief history see Table 1.

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  • In this study, structural features of Tricholoma matsutake polysaccharide (TMP-A) were investigated by a combination of infrared (IR) spectra, gas chromatography–mass spectrometry (GC–MS), nuclear magnetic resonance (NMR) spectroscopy. The results indicated that TMP-A had a backbone of 1,4-- d-glucopyranose residue which branches at O-6 based on the experimental results. The branches were mainly composed of an (1→3)--d-galactopyranose residue, and terminated with -d-xylopyranose residue.

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  • Tham khảo sách 'project gutenberg's on the antiquity of the chemical art, by james mactear', khoa học tự nhiên, hoá học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

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  • Carbon nanotubes are rolled up graphene sheets with a quasi-one-dimensional structure of nanometer-scale diameters. More than twenty years have passed since the pioneering work on carbon nanotubes by Prof. Iijima in 1991. During all these years, carbon nanotubes have at‐ tracted a lot of attention from physicists, chemists, material scientists, and electronic device engineers because of their excellent structural, electronic, optical, chemical, and mechanical properties.

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  • (BQ) Part 2 book "Advanced organic chemistry (Part A: Structure and mechanisms)" has contents: Carbanions and other carbon nucleophiles, addition; condensation and substitution reactions of carbonyl compounds; aromaticity; aromatic substitution; concerted pericyclic reactions; free radical reactions; photochemistry.

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  • Nanotechnology has received tremendous interest over the last decade, not only from the scientific community but also from a business perspective and from the general public. Although nanotechnology is still at the largely unexplored frontier of science, it has the potential for extremely exciting technological innovations that will have an enormous impact on areas as diverse as information technology, medicine, energy supply and probably many others. The miniaturization of devices and structures will impact the speed of devices and information storage capacity.

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  • Subduction is a major process that plays a first-order role in the dynamics of the Earth. The sinking of cold lithosphere into the mantle is thought by many authors to be the most important source of energy for plates driving forces. It also deeply modifies the thermal and chemical structure of the mantle, producing arc volcanism and is responsible for the release of most of the seismic energy on Earth. There has been considerable achievements done during the past decades regarding the complex interactions between the various processes acting in subduction zones.

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