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321.
We investigated occupied squirrel middens and squirrel sightings and vocalizations as indicators of red squirrel ( Tamiasciurus hudsonicus ) abundance in high-elevation whitebark pine ( Pinus albicaulis ) zone. Data were collected 1984-1989 from line transects located on 2 study sites in the Yellowstone ecosystem. We evaluated the performance of each measure on the basis of precision and biological considerations. We concluded that, of the 3 measures, active middens were the best indicator of red squirrel abundance. We also observed that the density of active middens dropped by 48%-66% between 1987 and 1989, following a severe drought and extensive wildfires that burned one of the study sites during 1988. 相似文献
322.
Classification Using Class Cover Catch Digraphs 总被引:2,自引:0,他引:2
Carey E. Priebe David J. Marchette Jason G. DeVinney Diego A. Socolinsky 《Journal of Classification》2003,20(1):003-023
class cover catch
digraphs based on proximity between training observations. Performance
comparisons are presented on synthetic and real examples versus
k-nearest neighbors, Fisher's linear discriminant and support vector
machines. We demonstrate that the proposed semiparametric classifier has
performance approaching that of the optimal parametric classifier in cases
for which the optimal is available for comparison. 相似文献
323.
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326.
J C David 《Experientia》1979,35(11):1483-1484
Phenylethanolamine, m-octopamine and p-octopamine contents were determined as a function of age in the hypothalamus and brain stem of spontaneously hypertensive rats and controls Wistar Kyoto. In hypothalamus, the content of the 3 amines was 2--4-fold greater for the SH rats. In the brain stem, the phenylethanolamine and p-octopamine contents were 2--3-fold greater in SH rats but 5--6-fold higher in the case of m-octopamine. The difference appears at 3 weeks and correlates the blood pressure with the increase of age. The significance of these findings is discussed. 相似文献
327.
328.
N Thiernesse A David J Bernard P Jeannesson D Zagury 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,285(6):713-715
The localization of Golgi areas, particularly lysosomal bodies detected by their acid phosphatase activities, has been determined in the cytotoxic lymphocytes conjugated to their target cell. The study points out the preferential situation of these organelles close to the contact area between the two cells during the target cell lysis. 相似文献
329.
本文对从分子的化学演化到形成生命这个从量变到质变的过程进行了新的探讨,同时对一些生命现象的本质作了全新的解释。 相似文献
330.
D David 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1977,284(11):949-952
The gonadic germ deficit induced by DDT in Quail embryos issued from eggs only treated at the first generation, partially decreases at the second generation and completely at the third. When the DDT treatment is repeated for each generation, the reduced effect slightly increases. 相似文献