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  • Cell & Developmental Biology  (152)
  • Organic Chemistry  (130)
  • 1990-1994  (208)
  • 1965-1969  (61)
  • 1940-1944  (13)
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  • 1
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The photophysics and photochemistry of N-amino-substituted pyridinium salts were investigated. Electron transfer from the amino group to the pyridinium ring takes place in the singlet excited state. The fluorescence quenching and photoreactivity of these compounds is conditioned by this process. Irradiation of N-aminopyridinium salts in solution leads to novel fused heterocycles or to triphenylpyridine, depending on the concentration of the initial compound. Free radical intermediates are involved in the photoreaction.
    Additional Material: 3 Ill.
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  • 2
    ISSN: 1040-452X
    Keywords: Embryonic stem cells ; Cell differentiation ; Pluripotency ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Ten embryonic stem (ES) cell lines from mink blastocysts were isolated and characterized. All the lines had a normal diploid karyotype; of the ten lines studied, five had the XX and five had the XY constitution. Testing of the pluripotency of the ES-like cells demonstrated that (1) among four lines of genotype XX, an X was late-replicating in three; both Xs were active in about one-third of cells of line MES8, and analysis of glucose-6-phosphate dehydrogenase revealed no dosage compensation for the X-linked gene; (2) when cultured in suspension, the majority of lines were capable of forming “simple” embryoid bodies (EB), and two only showed the capacity for forming “cystic” multilayer EBs. However, formation of ectoderm or foci of yolk sac hematopoiesis, a feature of mouse ES ceils, was not observed in the “cystic” EB; (3) when cultured as a monolayer without feeder, the ES cells differentiated into either vimentin-positive fibroblast-like cells or cytokeratin-positive epithelial-like cells (less frequently); neural cells appeared in two lines; (4) when injected into athymic mice, only one of the four tested lines gave rise to tumors. These were fibrosarcomas composed of fibrobalst-like cells, with an admixture of smooth muscular elements and stray islets of epithelial tissue; (5) when the ES cells of line MES1 were injected into 102 blastocyst cavities and subsequently transplanted into foster mathers, we obtained 30 offspring. Analysis of the biochemical markers and coat color did not demonstrate the presence of chimaeras among offspring. Thus the cell lines derived from mink blastocysts are true ES cells. However, their pluripotential capacities are restricted. © 1992 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
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  • 3
    ISSN: 0899-0042
    Keywords: methanephosphonic acid dichloride ; N,N′-bis(1-phenylethyl)diamidomethylphosphonate ; chiral discrimination on self-association ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiomeric (S,S)- and (R,R)-bis(1-phenylethyl)diamidomethylphosphonates, the phosphorus atom being prochiral, have been synthesized, starting from the methanephosphonic acid dichloride and corresponding chiral amines. The splitting observed in the 31P-NMR spectra of their nonracemic mixtures may be accounted for the self-discrimination of chiral species. This effect can be very useful for enantiomeric analysis of amines based on coupling reactions with methanephosphonic acid dichloride. © 1994 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 335 (1993), S. 699-704 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Mutual Promotion Effect of Molybdates in Multicomponent Molybdate CatalystsMulticomponent molybdate catalysts (e.g. of the composition Bi2Fe1,5Co7Cr10Mo19Oy) are produced by coprecipitation, drying and calcination. These catalysts exhibit high activity and selectivity in the ammoxidation of propene to acrylonitrile. The individual molybdates (Co-, Fe- and Cr-molybdate) exhibit no selectivity in the ammoxidation of propene. Therefore a mutual promotion effect of these molybdates exists. The cause of the promotion effect is the formation of the active and selective phase from the β-phase of Co-molybdate by exchange of protons with ions of Fe3+ and Cr3+ from the molybdates of Fe and Cr. The structure of this catalytic active and selective phase is similar to the structure of the β-phase of Co-molybdate.
    Additional Material: 7 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 33 (1966), S. 309-314 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nach Feststellung der Verfasser wird bei der photochemischen Oxydation des Furfurol-diäthylacetals zunächst der Furanring abgebrochen und dann die Diäthylacetalgruppe eliminiert, wobei der ψ-Ester der Maleinaldehydsäure entsteht. Beim Furfurol-divinylacetal jedoch bleibt die Eliminierung der Acetalgruppe aus, da die nach vorausgegangenem Furanringabbruch entstandene Verbindung polymerisiert.Ferner wird aufgezeigt, daß das aus dem ψ-Ester der Maleinaldehydsäure entstandene Oxim in der Tat ein Oxim der Fumaraldehydsäure ist.
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  • 6
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The efficiency of the developed method of dissymmetry functions was studied using various model systems. The alteration of the dissymmetry function was analysed with systematic variations of the bond lengths, valence angles and masses of atoms in model tetrahedra. The behaviour of the dissymmetry function was studied for conformationally labile systems and chiral polyhedra. In general, it was found that in all cases the alteration of the dissymmetry function is in agreement with the speculative representations of the changes in degree of chirality.
    Additional Material: 5 Ill.
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  • 7
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reduction of 9-cyanoanthracene by two equivalents of potassium in liquid ammonia was shown to yield the 9-cyanoanthracene dianion, whereas 1-naptho- and benzonitrile gave the cyanodihydroaryl anions corresponding to the protonation of nitrile dianions at a position para to the cyano group. The 9-cyanoanthracene dianion underwent the same transformation in the presence of a stronger protonating agent, methanol. According to 13C NMR spectral data of the generated species, the cyano group extracts the negative charge from the π-electronic system: ca 0·20:0·25 e in the case of the 9-cyanoanthracene dianion and ca 0·14:0·17 e in the case of cyanodihydroaryl anions. These estimations and the general NMR pattern of π-charge distribution in all the anionic species under investigation are in accordance with data from quantum molecular orbital calculations at the PM3 and INDO levels, being reflected by the fairly good linear relationships between the changes of ring carbon chemical shifts on going to the anionic species from the respective neutral precursors on the one hand and the calculated π-charges on the other. The para-orienting effect of the cyano group in the protonation of nitrile dianions is discussed in terms of the π-charge distribution in the starting dianion and the tendency to form a most stable cyanodihydroaryl anion isomer.
    Additional Material: 3 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 34 (1993), S. 53-57 
    ISSN: 1040-452X
    Keywords: Spermatozoa ; Gene expression ; Mutation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Basic chromosomal proteins were extracted from the sperm of fertile and infertile human males. The relative proportions of protamine 1, 2, and 3 were determined by scanning microdensitometry following electrophoresis of total protamine in polyacrilamide gels. The findings were as follows: (1) The proportion of protamine P(2 + 3) in sperm obtained from infertile males was lower than that in fertile males. (2) Protamine P(2 + 3) in infertile human males showed reduced affinity to DNA. The possibility that some cases of human male infertility may be due to mutation within the protamine P2 gene is discussed. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 39 (1994), S. 384-391 
    ISSN: 1040-452X
    Keywords: Transgene ; Mouse ; Embryo ; Microinjection ; PCR ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The production of transgenic animals from ungulate species is an inefficient and expensive procedure. The development of selection methods to identify the small number of transgenic preimplantation embryos produced following DNA microinjection of one-cell embryos would greatly reduce both the cost and effort of these procedures. This study has examined the fate of the ovine β-lactoglobulin-human α1-antitrypsin (AATB) minigene construct or a subfragment of this following microinjection into one-cell mouse embryos. It has examined two PCR-based methods that were designed to identify a biochemical difference between microinjected DNA constructs to select preimplantation stage embryos in which chromosomal integration of exogenous DNA has occurred. The two methods involved the modification of the AATB DNA construct either by dam-methylation or the substitution of dTTP by dUTP. The dam-sensitive DNA endonuclease Dpnl, that was used to digest nonintegrated AATB sequences at sites located between PCR oligonucleotide sequences, was found to interfere with the activity of the subsequent PCR reaction. Analyses of the fate of dUTP-DNA indicated that either repair or replication of microinjected DNA interfered with the ability to distinguish between integrated and nonintegrated DNA constructs in the mid-preimplantation stage embryo. The distribution of microinjected AATB DNA between the blastomeres of individual four and eight-cell stage embryos was also examined by the PCR reaction. Microinjected DNA was not found to be evenly distributed between all the blastomeres of individual embryos. © 1994 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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  • 10
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyrazines and pyridines occurring in a coffee concentrate are analyzed by two procedures. 24 compounds have been identified and the presence of some 10 more is revealed. The syntheses, mass and infrared spectral data of reference compounds are given.
    Additional Material: 6 Ill.
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