INHERITANCE OF RESISTANCE TO FOWL PARALYSIS (NEUROLYMPHOMATOSIS GALLINARUM)     

Biely J  Palmer VE  Lerner IM  Asmundson VS 《Science (New York, N.Y.)》1933,78(2011):42

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Signaling life and death in the thymus: timing is everything     

Werlen G  Hausmann B  Naeher D  Palmer E 《Science (New York, N.Y.)》2003,299(5614):1859-1863

T lymphocytes are generated in the thymus, where developing thymocytes must accept one of two fates: They either differentiate or they die. These fates are chiefly determined by signals that originate from the T cell receptor (TCR), a single receptor complex with a remarkable capacity to decide between distinct cell fates. This review explores TCR signaling in thymocytes and focuses on the kinetic aspects of ligand binding, coreceptor involvement, protein phosphorylation, and mitogen-activated protein kinase (MAPK) activation. Understanding the logic of TCR signaling may eventually explain how thymocytes and T cells distinguish self from nonself, a phenomenon that has fascinated immunologists for 50 years.  相似文献   

Confirmation of the Carolina slate belt as an exotic terrane     

Secor DT  Samson SL  Snoke AW  Palmer AR 《Science (New York, N.Y.)》1983,221(4611):649-651

An assemblage of Middle Cambrian Atlantic faunal province trilobites has been found in the rocks of the Carolina slate belt near Batesburg, South Carolina. Geologic and paleomagnetic data suggest that the Carolina slate belt and the adjacent Charlotte belt constitute an exotic terrane that was accreted to North America in early to middle Paleozoic time.  相似文献   

Topographic controls on the invasion of Pteronia incana (Blue bush) onto hillslopes in Ngqushwa (formerly Peddie) district,Eastern Cape,South Africa     

V. Kakembo  K. Rowntree  A.R. Palmer 《CATENA》2007

The role of topographic factors in the invasion of hillslopes by Pteronia incana, an unpalatable shrub, was investigated. The study combined field observations with image analysis based on high-resolution infrared imagery. A Digital Elevation Model (DEM) of 20 m spatial resolution was used to derive terrain parameters. The Topographic Wetness Index (WI), a component of the TOPMODEL, was derived from the DEM and its relationship with the spatial distribution of P. incana was explored. The absence/presence of P. incana was noted to be strongly influenced by slope angle and aspect. The probability for P. incana occurrence increased with slope steepness and southerly slope orientation. Abandoned and grazing lands were identified as the main invasion hotspots on hillslopes. The combined influence of slope gradient and aspect, and land use was noted to have promoted the invasion. This is borne out by the concentration of the invasion on abandoned steep slopes with a southerly orientation.  相似文献   

Birds in Western Australian wheatbelt reserves—implications for conservation     

D.J. Kitchener  J. Dell  B.G. Muir  M. Palmer 《Biological conservation》1982,22(2):127-163

Bird species richness in 22 reserves in the Western Australian wheatbelt was shown to be related not to isolation from adjacent uncleared land, either spatially or with time since clearing of land in their vicinity, but to area of reserve and certain reserve habitat variables. The nature of these relationships was examined with multiple regression analysis. Reserve area was the most important variable, except in some passerine groups, where numbers of plant species, vegetation associations, and plant life form and density classes in each vegetation stratum were, separately, more important than area. Eighty-two percent of the variation in the number of bird species was explained by area of reserve and number of plant species, indicating the importance of floristics to the total bird assemblage within reserves. The number of formations present (the broadest vegetation structural grouping used) did not explain any of the variation in species numbers in any of the bird groupings.There were more resident passerine species present in wheatbelt reserves than there were breeding passerine species on similar-sized southwestern Australian late-Pleistocene/Holocene islands, although the species versus area relationship of the resident habitat-specific passerines (P₅ group) was very similar to that of the island land-bird faunas. The P₅ species group contained many species which probably responded to wheatbelt reserves as islands; some of these species may fail to persist in the wheatbelt in the long term. Twenty-three species usually resident in reserves and 15 ‘non-residents’ were identified as being ‘vulnerable’ or of uncertain conservation status in the wheatbelt.Some vegetation formations within reserves were more important to birds than others; woodlands were most important both to resident and transient species. Most species do not appear to distinguish between shrublands and heaths as major habitats; Species richness versus formation area relationship suggest that insular patchiness for birds in the wheatbelt was manifest at the level of vegetation formations. Reserves as small as 80 ha were important sanctuaries for birds in the wheatbelt, although 1500 ha was considered a minimum area of reserve to conserve a local avifauna. Reserves of the order of 30,000–94,000 ha were required to contain most of the avifauna of the wheatbelt.  相似文献   

The mineralogy and potassium supplying power of some loessial and related soils of New Zealand     

A. Surapaneni  A. S. Palmer  R. W. Tillman  J. H. Kirkman  P. E. H. Gregg 《Geoderma》2002,110(3-4):191-204

Sixteen Pallic (Aqualfs, Ustalfs, Aquepts, Ochrepts) and related soils collected from the North and South Islands of New Zealand were studied to determine if variations in nonexchangeable K supply could be explained by mineralogical composition. A strong relationship was found which indicates that mica is weathering to vermiculite. Proportions of vermiculite and kandite are generally higher in the North Island than in the South Island. Dominance of either micas or vermiculite or kandite is determined by the stage of weathering and/or the nature of parent materials. Soils that supplied more nonexchangeable K (K_nex) to ryegrass plants contained more mica in the clay fraction than soils that supplied less K_nex. The results confirmed that use of a soil test that includes a measure of K_nex (i.e. acid-extractable K) may be a vital part of identifying variations in plant available K status of the soils. It is concluded that the K supplying power of the Pallic and related soils is related directly to the amounts of mica present in clay fraction and that good K supplying soils will be transformed to K depleted soils as a result of increased weathering and leaching (pedogenic factors) and K exploitation in intensive farming systems.  相似文献   

Retention of mercury in tissues of cattle and sheep given oral doses of a mercurial fungicide, Ceresan M     

F C Wright  J S Palmer  J C Riner 《Journal of agricultural and food chemistry》1973,21(4):614-615

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A computer model study of light interception by orchards in relation to mechanised harvesting and management     

J.E. Jackson  J.W. Palmer 《Scientia Horticulturae》1980,13(1):1-7

The introduction of mechanised harvesting often results in a redesign of the crop canopy. Computer models have been used to predict light interception, and hence potential yield, by a range of hedgerow tree forms and spacings as a guide to the design of orchard systems for mechanical harvesting. Light interception is increased by increasing tree height, thickness and leaf-area density, and by reducing the clear alleyway. Narrow hedgerows less than 2 m high will need straddle harvesting to avoid loss of light interception and yield.  相似文献   

Derrengue, a paralysis of cattle in El Salvador ascribed to ingestion of Melochia pyramidata.     

A C Palmer 《The Veterinary record》1975,96(25):547-548

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Secretory patterns and circadian and seasonal changes in luteinizing hormone, follicle stimulating hormone, prolactin and testosterone in the male pygmy goat   总被引：1，自引：0，他引：1  

D S Muduuli  L M Sanford  W M Palmer  B E Howland 《Journal of animal science》1979,49(2):543-553

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