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  • BIOTECHNOLOGY  (60)
  • PROPULSION SYSTEMS  (52)
  • Analytical Chemistry and Spectroscopy  (46)
  • ASTROPHYSICS
  • 1970-1974  (158)
  • 1955-1959
  • 1972  (158)
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Keywords
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  • 1970-1974  (158)
  • 1955-1959
Year
  • 1
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Changes in 13C and 14N chemical shifts of the nitro derivatives of nitrogen heterocycles upon ionization (anion or cation formation) are twofold - first a uniform paramagnetic or in the case of protonation, a uniform diamagnetic shift of all the ring resonances that parallels the changes in the respective ultraviolet spectra and must be caused by changes in the molecular excited states, and second - the influence of the conjugated nitro group. About one third of the total negative anion charge may be localized on the nitro group, which causes unusually large shifts of the ring 13C resonances in this case.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 153-160 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon, nitrogen and oxygen NMR spectra of some nitro derivatives of pyrrole and imidazole have been investigated. The 13C chemical shifts of para-carbons and the 17O chemical shifts of the nitro group correlate qualitatively with the electron densities on these carbon and oxygen atoms, which in turn depend upon the degree of conjugation of the nitro groups with the heterocyclic ring. Conjugation of several nitro groups with the benzene ring is in most cases not impaired by mutual interactions and the 13C shifts show good additivity. Such additivity is much worse in pyrrole and imidazole derivatives. Taken together with the diamagnetic nature of these deviations from additivity, this leads to a possible conclusion about the less pronounced conjugation of the nitro groups with the heterocyclic ring in heterocyclic dinitro derivatives.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 4 (1972), S. 453-462 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper presents a study of the chemical shift of the phenol hydroxyl group as a function of concentration and temperature in cyclohexane, methylcyclohexane and carbon tetrachloride solutions. The chemical shift of monomeric phenol has been found. For these solutions monomertrimer equilibrium is observed within the entire temperature range and within a wide concentration range. At low phenol concentrations, from 1 to 3 mole-%, the monomer-dimer equilibrium is observed in cyclohexane, methylcyclohexane and carbon tetrachloride solutions. Chemical shift of the hydroxyl group of trimeric phenol is temperature-dependent.From the experimental data the association constants and thermodynamic functions of the systems under study have been determined. The association constants differ for the above systems at the same temperatures. Association entropy ΔS changes from one system to another, while ΔH is the same for all systems.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of 1,1-dimethyl-1-silacyclobutane (I - as reported by Cherniak et al.),6, 1,1-dimethyl-1-germacyclobutane (II), 1,1,2,2-tetramethyl-1,2-disilacyclopentane (III) and 1,1,2,2-tetramethyl-1,2-digermacyclopentane (IV) are compared and some correlations between electron-impact fragmentation and thermal decomposition are derived. The mass spectra of the germanium compounds with respect to the silicone compounds are enriched by light fragment ions and exhibit lower intensities of odd-electron ions. The composition of some ions and apparently of neutral fragments coincides with that of the unstable intermediates which are suggested in the thermal decomposition mechanism of some related compounds. The loss of C2H4 is more characteristic under electron-impact as well as in thermal decomposition of Si-compounds, while C3H6 is preferable eliminated by the Ge-compounds.
    Additional Material: 1 Ill.
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  • 5
    Publication Date: 2019-06-27
    Description: The mathematical model of an integrated human thermal system is formulated. The system consists of an external thermal regulation device on the human body. The purpose of the device (a network of cooling tubes held in contact with the surface of the skin) is to maintain the human body in a state of thermoneutrality. The device is controlled by varying the inlet coolant temperature and coolant mass flow rate. The differential equations of the model are approximated by a set of algebraic equations which result from the application of the explicit forward finite difference method to the differential equations. The integrated human thermal system is simulated for a variety of combinations of the inlet coolant temperature, coolant mass flow rate, and metabolic rates.
    Keywords: BIOTECHNOLOGY
    Type: Computers in Biology and Medicine; 2; 1972
    Format: text
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  • 6
    Publication Date: 2019-06-27
    Description: A preliminary mission study of a reusable vehicle from staging to orbit indicates payload advantages for a dual-propulsion system consisting of separate scramjet and rocket engines. In the analysis the scramjet operated continuously and the initiation of rocket operation was varied. For a stage weight of 500,000 lb the payload was 10.4 percent of stage weight or 70 percent greater than that of a comparable all-rocket-powered stage. When compared with a reusable two-state rocket vehicle having 50,000 lb payload, the use of the dual propulsion system for the second stage resulted in significant decreases in lift-off weight and empty weight, indicating possible lower hardware costs.
    Keywords: PROPULSION SYSTEMS
    Type: NASA-TN-D-6762 , E-6555
    Format: application/pdf
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  • 7
    Publication Date: 2019-06-27
    Description: Changes in forearm muscle blood flow (FMBF) during direct whole-body heating were measured in 17 normal subjects using three different methods. We conclude that FMBF is not increased by direct whole-body heating. Since renal and splanchnic blood flow fall 30% under these conditions, maximal total skin blood flow in 12 previously studied subjects can be estimated from the rise in cardiac output to be 7.6 L/min (3.0-11.1 L/min).
    Keywords: BIOTECHNOLOGY
    Type: Journal of Applied Physiology; 32; Apr. 197
    Format: text
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  • 8
    Publication Date: 2019-06-27
    Description: The mathematical model of an integrated human thermal system is formulated. The system consists of an external thermal regulation device on the human body. The purpose of the device (a network of cooling tubes held in contact with the surface of the skin) is to maintain the human body in a state of thermoneutrality. The device is controlled by varying the inlet coolant temperature and coolant mass flow rate. The differential equations of the model are approximated by a set of algebraic equations which result from the application of the explicit forward finite difference method to the differential equations. The integrated human thermal system is simulated for a variety of combinations of the inlet coolant temperature, coolant mass flow rate, and metabolic rates. Two specific cases are considered: (1) the external thermal regulation device is placed only on the head and (2) the devices are placed on the head and the torso. The results of the simulation indicate that when the human body is exposed to hot environment, thermoneutrality can be attained by localized cooling if the operating variables of the external regulation device(s) are properly controlled.
    Keywords: BIOTECHNOLOGY
    Type: Computers in Biology and Medicine; 2; Feb. 197
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  • 9
    Publication Date: 2019-08-13
    Description: Human skeletal muscle may be regarded as an electro-mechanical transducer. Its physiological input is a neural signal originating at the alpha motoneurons in the spinal cord and its output is force and muscle contraction, these both being dependent on the external load. Some experimental data taken during voluntary efforts around the ankle joint and by direct electrical stimulation of the nerve are described. Some of these experiments are simulated by an analog model, the input of which is recorded physiological soleus muscle EMG. The output is simulated foot torque. Limitations of a linear model and effect of some nonlinearities are discussed.
    Keywords: BIOTECHNOLOGY
    Type: NASA, Washington 7th Ann. Conf. on Manual Control; p 115-118
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  • 10
    Publication Date: 2019-07-13
    Description: The stabilizing influence of acoustic cavities (quarterwave acoustic resonators) on acoustic modes of combustion instability has been studied. The ability to analytically predict cavity damping was improved. Relatively good agreement between predicted damping and measured stability was demonstrated. Full-scale motor firings were made to evaluate the influence of several parameters on stability. Results from these firings showed that stability was changed, but not dramatically, by changes in the engine operating conditions. Variations in the film-coolant flowrate do not significantly affect cavity stabilization. The ability to stabilize an engine with unconventional cavity configurations was demonstrated.
    Keywords: PROPULSION SYSTEMS
    Type: AIAA PAPER 72-1147 , Joint Propulsion Specialist Conference; Nov 29, 1972 - Dec 01, 1972; New Orleans, LA; US
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