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71.
Bonnie J. Reger Maurice S.B. Ku Jeffrey W. Pottert John J. Evans 《Phytochemistry》1983,22(5):1127-1132
The ribulose-1,5-bisphosphate carboxylase/oxygenase purified from maize (a C4 monocot) to homogeneity has a MW of532 000 and sedimentation coeffici 相似文献
72.
Mim Dixon Wayne W. Myers Patricia A. Book Philip O. Nice 《The Western journal of medicine》1983,139(6):917-922
Before Western contact, Alaskan Native populations were self-sufficient in their health practices. Slowly, the Native health care system was replaced by a Western one which was highly effective in treating infectious diseases. As infectious diseases were brought under control by the Indian Health Service, the emergent leading health problems were related to violence, attributed in part to cultural disintegration. New types of Native health providers and new Native-controlled institutions evolved to provide culturally appropriate health and mental health services and to promote a stronger cultural identity. 相似文献
73.
Hemming Fiona J. Begeot Martine Dubois Maurice P. Dubois Paul M. 《Cell and tissue research》1983,234(2):427-437
Corticotropes of rat fetuses aged 16, 18 and 21 days were localized by the indirect antibody-enzyme method on semithin sections of the pituitary. The development of the ultrastructure of these cells was observed on consecutive ultrathin sections. In comparison with previous data our present results show that identification of a fetal cell type cannot be based entirely on morphological criteria. The structural peculiarities of corticotropes obtained from studies in vivo are compared with those observed in cells maintained in vitro. 相似文献
74.
75.
A Haxo-Blinks rate-measuring oxygen electrode together with a modulated light source gave an average current signal (change in net O2 exchange) and a modulated current signal (photosynthetic O2 evolution). Using this apparatus, net O2 exchange and photosynthetic O2 evolution at low intensities have been studied in the green alga, Chlamydomonas reinhardi. At both 645 nm and 695 nm, the curves of net O2 exchange as a function of light intensity were steeper at lowest intensities than about compensation, indicative of the Kok effect. The effect was greater at 695 nm than at 645 nm. The corresponding curves of photosynthetic O2 evolution, on the other hand, showed no Kok effect; here, the slope was lowest at lowest intensity. The absence of the Kok effect in O2 evolution, together with its sensitivity to monofluoroacetic acid, show that it is due to an interaction of photosynthesis and respiration. The effect was exaggerated by 3-(3,4-dichlorophenyl)-1,1-dimethylurea. In the presence of concentrations of this inhibitor sufficient to inhibit O2 evolution completely, a light-induced change in net O2 exchange remained. This was interpreted as a system I dependent depression of respiratory O2 uptake. The Kok effect remained undiminished in concentrations of carbonyl cyanide m-chlorophenylhydrazone and 2,4-dinitrophenol which partially uncoupled either oxidative phosphorylation alone or both oxidative and photosynthetic phosphorylations. The above results can be explained within a model of the Kok effect in which O2 uptake is depressed by diversion of reductant away from respiratory electron transport and into photosystem I. The same photodepression of O2 uptake also appears to account for a transient in net O2 exchange seen in several algae upon turning off the light. 相似文献
76.
77.
Summary Nitrogen fixation in the natural, Agropyron-Koeleria grassland ecosystem was studied using the C2H2-C2H4 and N15 assays. Small soil samples and also undisturbed soil cores were used for analyses. Both techniques indicated that grassland
and associated cultivated soils had low fixation rates (0.6–1.8 kg/ha per 28 days in the laboratory and, 1 kg/ha per season
under actual field conditions). Algal colonies (Nostoc spp.) on the soil surface were active fixers when the surface of the grassland was moist. However, their small biomass limits
the extent of fixation in most areas.
In native grassland, 16 legumes bore nodules. The three most common speciesVicia americana, Thermopsis rhombifolia andOxytropis sericea, all of which had active nodules, contributed 10 per cent of the total nitrogenase activity.
The non-legumesElaeagnus commutata andShepherdia argentea were profusely nodulated with active nodules, but were confined to specific habitats. No nodules were found onArtemisia orOpuntia spp.
The major, heterotrophic, asymbiotic bacteria in the soil were clostridia. These utilize substrates produced by aerobic cellulose
and hemicellulose degrading organisms to fix N in anaerobic microsites. The C2H2:N2 reduction ratio was 3 to 1 in large, aerobic core samples, but was greater under water-logged conditions where high fixation
rates occurred. 相似文献
78.
79.
Maurice Cross 《BMJ (Clinical research ed.)》1969,4(5686):808-809
80.
Therapy of Staphylococcal Infections in Monkeys. IV. Further Comparison of Triacetyloleandomycin and Erythromycins 总被引:4,自引:2,他引:2
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Intravenous inoculation of a penicillin-resistant, phage type 80/81 staphylococcus caused lethal infection in 8 of 15 untreated monkeys. Daily intragastric administration of 50 mg/kg of triacetyloleandomycin, erythromycin estolate, and erythromycin ethylsuccinate was followed by mortalities of 0 of 16, 3 of 16, and 3 of 10, respectively. At dose levels of 25 and 12.5 mg/kg, none of 7 and 4 of 7 receiving triacetyloleandomycin and erythromycin estolate, respectively, died, as compared to 3 of 4 deaths in controls. In vitro sensitivity data and serum antibacterial levels would suggest that triacetyloleandomycin would be the least effective therapeutically. However, this prediction was not fulfilled in these studies of experimental infections in monkeys wherein triacetyloleandomycin was a very effective antimicrobial agent. 相似文献