Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 30

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych:  surface area
help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
The literature provides all the data needed to calculate the ratio between the amount of haemoglobin and the total surface area of erythrocytes in 54 species of mammals ranging in body mass from 2.5 g to more than 1000 kg. Analysis shows that the concentration of haemoglobin (Hb; g%) does not defend on the body mass ofthe mammals studied. The number of erythrocytes in 1 mm of blood (RBC; 10 x mm ) is significantly lower, and the diameter of these cells significantly higher, among larger mammals as opposed to smaller ones. The result is that the total surface area of erythrocytes in 1 mm of blood (TSAE; mm x mm ) is significantly lower among larger mammals, while the Hb/TSAE ratio (pg x ^m- ) is significantly greater. These results point to the smaller size of erythrocytes of smaller mammals permitting much greater numbers to exist, thereby producing a greater TSAE and smaller Hb/TSAE ratio. The greater total surface area of red blood cells per unit volume of blood in small mammals can in turn be presumed to allow for full saturation of haemoglobin by oxygen, even where the period of contact between erythrocytes and air in the lungs is shorter than in their larger counterparts.
An anatomical study was undertaken in order to investigate whether the sizes of selected human skull foramina with significant venous compartments correlated significantly with skull capacity. A total of 100 macerated human skulls were examined to determine the diameter of the foramina and the skull capacity. Measurements of the surface area of the foramina were made using a computerised digital analysis system. Only the size of the hypoglossal canal and jugular foramen were found to correlate significantly with the capacity of the skull. This correlation, together with the considerable size of the hypoglossal canal, indicated its important role in the venous drainage of the brain. There was considerable centralisation of venous outflow from the brain, with 60% of the area of all venous foramina of the skull occupied by jugular foramina. Asymmetry between the right and left jugular foramina was identified, with an average ratio of 1.6 (ranging between 1 and 3.47). In the case of right-sided domination the correlation between the skull capacity and the size of both jugular foramina was negative (the larger the skull cavity, the less the asymmetry), while in the case of left-sided domination the correlation was positive. Perhaps the left-sided domination is less advantageous for the haemodynamics of blood outflow, as the left brachiocephalic vein is longer and is often compressed by the sternum and aortic arch.
In a few recent decades, population increase of the wild boar has been evidenced in various European countries. As the result of this increase, the wild boar has expanded into farmlands, especially in some regions, where the cultivated maize constitutes the main source of its diet through the larger part of the year. The effect of winter weather and land use changes on the expansion of wild boar was analysed in a farmland in southern Poland. Over 21 years (1985–2005) in the study area of about 681 km² a rapid increase in the number of harvested wild boars was recorded. While in the middle 1980′s, there were only about 40 animals harvested per hunting season, in 2005 the number increased to 180. The rapid increase was, in general, correlated positively to the increasing surface area of the maize crops — from 205 ha (0.9%) in 1985 to 3212 ha (14.9% of arable lands) in 2004. However the correlation between the increase of the average late winter (February/March) temperature and the number of wild boars seems to be negative and contrary to our expectations, the numbers of wild boars were found to be higher under the lower temperatures in that period of the year.
Corn and potato starches were physically modified by heating at 130 and 200°C or microwaving. On a basis of the results obtained it was found that upon heating or microwaving the content of amylose decreased and the reduction capacity increased for most of the modified starch preparations and all the preparations had an increased swelling capacity and water solubility. The greatest changes were observed for the preparations heated at 200°C, irrespective of starch. Microwave radiation caused slighlty smaller changes in the properties of starches. In the case of the preparations from potato starch it was observed a considerable increase in specific surface area of granules, an increase in volume of mesopores, and a decrease in their average diameter. The changes in these values were small in the preparations from corn starch.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.