1,720,972 research outputs found
Difosfani binaftilici P,P’-eterotopici privi di simmetria C2. Sintesi ed applicazioni in catalisi asimmetrica
No full textP,P’-Heterotopic Binaphthyl Diphosphanes Devoid of C2-Symmetry. Synthesis and Application in Asymmetric Catalysis
No full text
BINAPS: An Axially Chiral P,S-Heterodonor Ligand for Asymmetric Catalysis Based on Binaphthalene Backbone
No full textThe chelating P,S-heterodonor ligand 2-diphenylphosphanyl-1,1′-binaphthalene-2′-thiol (11) (BINAPS), which features a chiral axis as the unique stereogenic element, has been prepared in both racemic and enantiopure form through a multistep reaction sequence using 2,2′-dihydroxy-1,1′-binaphthalene (BINOL) as the starting material. The reaction sequence is completely stereoconservative and (S)-11 is obtained with no loss of enantiopurity from pure (S)-BINOL. (R)-11 can be alternatively obtained by resolution of racemic 11 using the chiral (S)-benzylaminato Pd(II)-complex 19 as the resolving agent. The S-methyl or the S-i-propyl derivatives 14 have been used as chiral ligands in the Rh(I)-catalyzed asymmetric hydroformylation of styrene and in the hydrogen transfer reduction of acetophenone with modest success (up to 20% ee). In the presence of suitable Pd-complexes the same ligands provide higher ees in the hydrosilylation of styrene (50% ee) and in the allylic alkylation of 1,3-diphenylprop-2-enyl acetate (60% ee)
Application of DNA microarray technology in Bos taurus genomic analysis: preliminary results.
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Ultra high molecular weight polyacrylamides as DNA sieving matrices for microchip electrophoresis
No full textSan Diego, Californi
Synthesis, Resolution and Use in Enantioselective Catalysis of an Axially Chiral Binaphthyl-Templated P,S-Heterodonor Ligand (BINAPS)
No full textUse of peptide nucleic acid probes for detecting DNA single-base mutations by capillary electrophoresis
No full textPeptide nucleic acid (PNA) oligomers can be used as probes in pre-gel hybridization experiments, as an alternative to Southern hybridization. In this technique, the PNA probe is hybridized to a cyanine-5 labeled DNA sample denatured at low ionic strength, and the mixture is directly injected for size separation into a capillary electrophoresis (CE) system equipped with laser-induced fluorescence (LIF) detector. The neutral backbone of PNA allows hybridization to occur at low ionic strength and assures an efficient CE separation of the PNA/DNA hybrids from both double-stranded and single-stranded DNA. We have used as a model system the cystic fibrosis R553X and R1162X single-base mutations and we have assessed the influence of various factors, such as temperature and denaturants concentration on DNA/PNA hybrid stability in order to achieve the high specificity required for a single base pair discrimination
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