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Fahr 《European Journal of Forest Research》1941,63(7):152-156
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The objective of this study was to investigate the origin of chromosome segments of maize (Zea mays L.) inbred B86 from its parental inbreds B52 and Oh43 using RFLPS. B86 was selected to combine resistance to the first and second brood of the European corn borer with the favorable agronomic performance of Oh43. RFLP analyses of the three inbreds were performed with three restriction enzymes (EcoRI, EcoRV, HindIII) and 178 DNA probes covering all ten maize chromosomes. For two DNA probes in combination with one enzyme, B86 showed a new RFLP pattern not present in the two parents. Based on results from 119 polymorphic DNA probes, the proportion of the B86 genome contributed by B52 (51.3 %) and Oh43 (48.7 %) was almost equal. 相似文献
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McComas DJ Alexashov D Bzowski M Fahr H Heerikhuisen J Izmodenov V Lee MA Möbius E Pogorelov N Schwadron NA Zank GP 《Science (New York, N.Y.)》2012,336(6086):1291-1293
As the Sun moves through the local interstellar medium, its supersonic, ionized solar wind carves out a cavity called the heliosphere. Recent observations from the Interstellar Boundary Explorer (IBEX) spacecraft show that the relative motion of the Sun with respect to the interstellar medium is slower and in a somewhat different direction than previously thought. Here, we provide combined consensus values for this velocity vector and show that they have important implications for the global interstellar interaction. In particular, the velocity is almost certainly slower than the fast magnetosonic speed, with no bow shock forming ahead of the heliosphere, as was widely expected in the past. 相似文献
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J Schulz R D Fahr G Finn I Naumann 《Tier?rztliche Praxis. Ausgabe G, Grosstiere/Nutztiere》1999,27(2):92-98
In dairy goats there is less evidence for relationships between udder form traits, results of physical udder examinations and mastitis indicators in the milk than in dairy cows. In 413 goats (predominantly Weisse Deutsche Edelziege and Bunte Deutsche Edelziege) from five herds (free from C.A.E.) repeated investigations of 2537 udder halves and fore milk samples were carried out in order to compare udder traits with findings in the milk. Less than 20% positive bacteriological findings and a low incidence of clinical mastitis testified a good clinical udder health status of the herds. Small teat-floor distances, loose hanging of the udders and bottle-shaped teats, findings which tended to become more frequent as lactation and lactation numbers progressed, indurative alterations of the mammary tissues and the teats tended to be connected with higher milk cell counts (> 1 million/microliter), more polymorphonuclear milk cells (> 40%), higher electrical milk conductivity (> 6.8 mS/cm) and lower milk lactose content (< 4.6%). A similar effect had a bad state of foot trimming. It is proposed to include the studied udder traits into herd health programs and breeding schemes for goats. 相似文献
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Skrzypek R Wójtowski J Fahr RD 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2004,51(3):127-131
The aim of this paper was a retrospective analysis of factors affecting the somatic cell count (SCC) in cow bulk tank milk. The investigations concerned the year 2000 and were conducted on 212 family dairy farms in the Wielkopolska region (Western Poland). The average herd size was 13.3 cows (ranging from 5 to 48), whereas the mean SCC was 269,000 in 1 cm3 of milk (ranging from 63,000 to 631,000). In the period from July to September a higher SCC (P < or = 0.01) was found than in the other months. In herds of more than 15 cows, higher SCC values (P < or = 0.05) were observed than in the smaller herds. The following management and technological factors significantly decreased SCC: a 7-8-week dry period (versus shorter period), foremilking with the use of a forestripper, practicing manual udder massage before milking, individual rationing of feeds according to production, and the application of MgO and beta-carotene additives to the feed ration. 相似文献
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Christoph F.J. Meyer Ludmilla M.S. Aguiar Julio Baumgarten Jean-François Cosson Jakob Fahr Neil Furey Robert Hodgkison Kirsten G. Jung Thomas H. Kunz Isabel Moya Paul A. Racey Erica M. Sampaio Christian C. Voigt Christa D. Weise 《Biological conservation》2010,143(11):2797-2807
Bats are ecologically important mammals in tropical ecosystems; however, their populations face numerous environmental threats related to climate change, habitat loss, fragmentation, hunting, and emerging diseases. Thus, there is a pressing need to develop and implement large-scale networks to monitor trends in bat populations over extended time periods. Using data from a range of Neotropical and Paleotropical bat assemblages, we assessed the ability for long-term monitoring programs to reliably detect temporal trends in species abundance. We explored the magnitude of within-site temporal variation in abundance and evaluated the statistical power of a suite of different sampling designs for several different bat species and ensembles. Despite pronounced temporal variation in abundance of most tropical bat species, power simulations suggest that long-term monitoring programs (?20 years) can detect population trends of 5% per year or more with adequate statistical power (?0.9). However, shorter monitoring programs (?10 years) have insufficient power for trend detection. Overall, our analyses demonstrate that a monitoring program extending over 20 years with four surveys conducted biennially on five plots per monitoring site would have the potential for detecting a 5% annual change in abundance for a suite of bat species from different ensembles. The likelihood of reaching adequate statistical power was sensitive to initial species abundance and the magnitude of count variation, stressing that only the most abundant species in an assemblage and those with generally low variation in abundance should be considered for detailed population monitoring. 相似文献
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Bruno Agossou Djossa Jakob Fahr T. Wiegand B. E. Ayihouénou E. K. Kalko B. A. Sinsin 《Agroforestry Systems》2008,72(3):205-220
The shea tree, Vitellaria paradoxa, is a socio-economically important tree for the rural population in parts of West Africa.
Our study assessed the current status of this native tree species with regard to increasing human pressure in northern Benin.
We compared distribution of adult shea trees, seedlings and saplings in farmed lands with protected areas in the Biosphere
Reserve of Pendjari (BRP). At our study site near BRP, agricultural activities foster recruitment of shea trees by regularly
cropping of vegetation cover. Furthermore, traditional farming practices preserve adult individuals thus permitting regular
fruit harvests. Consequently, most of the tallest and largest individuals of shea trees are found in framed lands. In contrast,
the highest density of juvenile trees including seedlings (dbh <5 cm) and saplings (dbh 5–10 cm) occurred within BRP. Saplings
were negatively affected by farming activities. Furthermore, spatial point pattern analysis revealed differences in the spatial
structure of juveniles. Juveniles showed significant aggregations at small scale (<20 m) in BRP as well as significant and
positive small-scale associations with adult trees. This contrasts with farmed lands where we did not find such spatial patterns
at similar small scale but only a weak aggregation between juveniles and absence of association (attraction) of adults to
juveniles. Although our analyses indicate that shea trees are rather well preserved, we conclude that the observed severe
reduction of saplings in farmed lands is likely to negatively impact the long-term viability of the tree population. Therefore
agroforestry practices must consider the preservation of sapling populations in farming areas for long-term conservation. 相似文献
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