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21.
In a group of 84 pairs of 11-year-old children of both sexes, the level of the alpha1-antitrypsin (alpha1-AT) were ascertained in the autumn and spring. Although the mean levels of alpha1-AT in the two seasons hardly differed, the highly significant seasonal changes in the distribution curves of alpha1-AT values were noted in boys, whereas the levels showed higher stability in girls. 相似文献
22.
Many rangelands in the southwestern United States provide quality habitat for Northern Bobwhites ( Colinus virginianus ). These same habitats are frequently managed for livestock production and thus are subjected to various brush management practices that are meant to enhance forage production. Bobwhites rely on woody cover for food, thermal and loafing cover, and protection from avian predators. Implementing brush management practices that reflect bobwhite requirements is important for managing usable space and viable populations. We described the structural vegetative characteristics associated with bobwhite locations and random locations on native rangelands in the upper Rolling Plains of Texas that are dominated by honey mesquite ( Prosopis glandulosa ) and managed with aerial herbicide and prescribed fire. We also used binary logistic regression to model habitat selection; the initial model was built using 67% of the data ( n = 179 used-random paired points) and then validated using the remaining 33% of the data ( n = 88 used-random paired points). Locations used by bobwhites had significantly larger mean values of percent brush canopy cover, visual obstruction, and angle of obstruction than did random locations; random locations had a greater mean value of percent bare ground than locations used by bobwhites. The resulting logistic regression model contained only the angle of obstruction; the model had an 80% probability of correctly classifying used and random locations based on the area under the receiver operating curve (ROC). The model maintained a high classification probability when applied to the smaller validation data set, with an area under the ROC of 0.78. 相似文献
23.
The influence of current year foliage age on food consumption and utilization by the western spruce budworm, Choristoneura occidentalis (Lepidoptera:Tortricidae), was examined. Larvae were fed immature foliage of Douglas-fir ( Pseudotsuga menziesii var. glauca ), Engelmann spruce ( Picea engelmannii ), and corkbark fir ( Abies lasiocarpa var. arizonica ) in June and August of 1981 and Douglas fir in June and July of 1982. All larvae feeding on early season (June) foliage reached maturity. Larvae feeding on middle (July) and late (August) season foliage died before reaching pupation. Relative growth rate and efficiency of conversion of ingested food decreased with foliage age in both the 1981 and 1982 experiments. Relative consumption rate increased with foliage age in the 1981 and decreased in the 1982 experiment. 相似文献
24.
25.
Retinoblastoma. A transcriptional tryst 总被引:12,自引:0,他引:12
26.
D. Reinhardt J. Wagner H. J. Schümann 《Cellular and molecular life sciences : CMLS》1973,29(7):830-832
Zusammenfassung Am Kaninchen-Ileum besteht die durch Temperaturerhöhung bedingte Rechtsverschiebung der Dosis-Wirkungs-Kurven von Isoprenalin und Th 1165a aus einem reversiblen und einem irreversiblen Anteil. 相似文献
27.
I. Palik M. Zs. Koltai M. Wagner I. Kolonics G. Pogátsa 《Cellular and molecular life sciences : CMLS》1982,38(8):934-935
Summary The conductivity of the coronary arterial bed increased in healthy and decreased in alloxan-diabetic dogs in response to intracoronary administration of norepinephrine or sympathetic stimulation. This suggests a modification of adrenergic receptors sensitivity in diabetes. 相似文献
28.
Scanning immunoelectron microscopy of mouse B and T lymphocytes 总被引:5,自引:0,他引:5
29.
30.
The tropics have been suggested as the drivers of global ocean and atmosphere circulation and biogeochemical cycling during the extreme warmth of the Cretaceous period; but the links between orbital forcing, freshwater runoff and the biogeochemistry of continental margins in extreme greenhouse conditions are not fully understood. Here we present Cretaceous records of geochemical tracers for freshwater runoff obtained from a sediment core off the Ivory Coast that indicate that alternating periods of arid and humid African climate were driven by orbital precession. Our simulations of the precession-driven patterns of river discharge with a global climate model suggest that ocean anoxia and black shale sedimentation were directly caused by high river discharge, and occurred specifically when the northern equinox coincided with perihelion (the minimum distance between the Sun and the Earth). We conclude that, in a warm climate, the oceans off tropical continental margins respond rapidly and sensitively to even modest changes in river discharge. 相似文献