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  • 1
    ISSN: 1436-5073
    Keywords: infrared spectroscopy ; thermal analysis ; polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 34 compounds containing the SO2-N-C-N-moiety are investigated by means of infrared spectroscopy and differential scanning calorimetry to study problems of polymorphic species. There are arguments for different crystalline solids of 16 sulphonyl derivatives. The phenomenon of polymorphism can be discussed both in terms of different hydrogen bonding and conformational effects. Although two tautomers are thinkable for the compounds being investigated the sulphonylimino structure is assumed to yield the most stable state.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 340 (1998), S. 608-612 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The syntheses and the properties of new sulfurligated liquid crystalline sulfones, containing biphenyl units, as well as the influence of lateral nitro groups on their phase behaviour are described. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction measurements reveal liquid crystalline properties for most of the synthesized bis(4-alkoxy-biphenyl-3-yl)sulfones (4). The mesomorphic behaviour of these compounds is compared with that of the corresponding nitro compounds 6. The bis(4-alkoxy-6-nitrobiphenyl-3-yl)sulfones (6) are not mesogenic. The results demonstrate that lateral nitro groups introduced into the biphenyl unit, changing the length-breadth relation, depress the thermal stability and lead to the loss of the mesomorphic properties.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 269-271 
    ISSN: 0947-3440
    Keywords: Sodium cyanodithioformate ; Hydrazines, monosubstituted ; Thiooxamic acid derivatives ; Zwitterionic compounds ; Glyoxylamide bis(phenylhydrazone) ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sodium cyanodithioformate (1) reacts with methylhydrazine (2) only in the presence of H2S to give the new, zwitterionic thiooxamic acid 1-(2-methylhydrazide) 2-(2-methylhydrazone) (3) in good yield. The reaction of 1 with phenylhydrazine (5) gives a mixture of the zwitterionic thiooxamic acid 1-(2-phenylhydrazide) 2-(2-phenylhydrazone) (6b) and the non-zwitterionic glyoxylamide bis(phenylhydrazone) (7). The mechanism of the formation of 3 and 6b is discussed. X-ray structural data of 3 and 6b are given.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of plant pathology 103 (1997), S. 203-215 
    ISSN: 1573-8469
    Keywords: population growth ; food supply ; productivity ; crop losses ; no control scenario ; no loss scenario
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Actual and potential crop losses of eight major food and cash crops have been estimated by evaluating data from literature and field experiments. Total losses were calculated from yield reductions due to pathogens, animal pests and weeds on a regional, continental and global level. Since 1965, worldwide production of most crops has increased considerably. Simultaneously, crop losses in wheat, potatoes, barley and rice increased by 4 to 10 percent, in maize, soybean, cotton and coffee losses remained unchanged or slightly decreased. The efficacy of crop protection practices was calculated as the percentage of potential losses prevented by control. The efficacy is highest in cotton (55 percent), it reaches only 34 to 38 percent in the food crops rice, wheat and maize. The variability among cropping areas is high: In Western Europe, 61 percent of potential crop losses is prevented, in North America and Oceania 44, in all other regions 38 percent. Due to the small share of Western Europe in worldwide production of 8 percent, the efficacy of actual crop protection worldwide is only 40 percent. In view of population growth and rising food demand crop production has to be increased substantially. As potential loss rates often increase with attainable yields high productivity largely depends on effective crop protection management. Scenarios for the production of food crops by the year 2025 in developed and in developing countries are given. Recent and future developments in crop protection can contribute to establish sustainability in agriculture and to preserve natural resources. However, although effective control methods have been developed for most biotic yield constraints, the use of crop protection products is regulated by economic considerations rather than by food demand.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 13 (1961), S. 118-120 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es wird eine neue Synthese des N(2-Pyridyl)-glycins durch Hydrierung eines Gemisches von 2-Aminopyridin und Glyoxylsäureäthylester unter Verwendung von Palladium-Tierkohle-Katalysator beschrieben.
    Type of Medium: Electronic Resource
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