排序方式： 共有15条查询结果，搜索用时 0 毫秒
11.
JohnR. Fike RichardA. LeCouteur ChristopherE. Cann 《Veterinary radiology & ultrasound》1981,22(6):236-243
High resolution computed tomography (CT) was used to determine the normal appearance of the brain of an adult Beagle dog. Objects as small as 0.6 mm for bony structures (high contrast) and 1.5–2.0 mm for soft tissue structures (low contrast) could be resolved in the CT images. Multiplanar imaging using direct transverse and reformatted dorsal and sagittal images made it possible to obtain a three dimensional presentation of anatomy. Selective viewing, where CT number window and level settings were varied, was used to optimize visualization of specific brain structures. Normal high contrast components, cerebrospinal fluid, and osseous land-marks, were important aids in identification of various intracranial structures. Quantitative densitometry was performed to characterize various regions of the brain in terms of their x-ray attenuation values or CT numbers. This study indicated that high resolution CT provides a qualitative and quantitative appraisal of the canine brain that is unavailable using conventional radiographic technics. 相似文献
12.
John R. Stommel Marija Pushko Kathleen G. Haynes Bruce D. Whitaker 《Plant Breeding》2014,133(6):788-793
Colour is a critical determinant of fruit and vegetable quality. We characterized the inheritance of black and violet immature pepper fruit colour and chlorophyll, carotenoid and anthocyanin pigments responsible for fruit colour. Segregation for black vs. violet fruit colour deviated from expectations for simple inheritance. The primary determinant of fruit colour was the concentration of chlorophyll and carotenoid pigments relative to anthocyanin concentration. Whereas anthocyanin concentration was 34% greater in violet fruit, chlorophyll and carotenoid concentrations were 20‐fold and fourfold greater, respectively, in black fruit relative to concentrations found in violet fruit. Measurement of Commission Internationale d'Eclairage (CIE) colour space scores revealed larger a* values and smaller b* values for violet fruit relative to corresponding parameters for black fruit. An additive–dominance model was sufficient to explain the variation in individual fruit pigments as well as the CIE parameter a*. Addition of additive × additive effects to the additive–dominance model resulted in the best‐fit model m[d][h][i] for L* and b* colour space parameters. For all pigment classes, significant additive effects contributed to the genetic variance for fruit colour. 相似文献
13.
RichardA. LeCouteur JohnR. Fike ChristopherE. Cann VincentG. Pedroia 《Veterinary radiology & ultrasound》1981,22(6):244-251
Computed tomography (CT) was used to investigate brain tumors in the caudal fossa of three dogs. Changes detected by CT included compression or distortion of cerebrospinal fluid spaces within the caudal fossa, and changes in parenchymal density before and after intravenous injection of a nondiffusible, iodinated contrast medium. CT provided information regarding tumor size, location, character, and relationships with normal caudal fossa structures. It was concluded that CT offered advantages over technics currently in use for diagnosis and assessment of caudal fossa lesions in the dog. 相似文献
14.
Elena Albrecht Dapeng Zhang Robert A. Saftner John R. Stommel 《Genetic Resources and Crop Evolution》2012,59(4):517-538
Capsicum baccatum is one of five domesticated pepper species which, despite its morphological and ecological variability, has been underexploited
for germplasm improvement. Utilizing a broad spectrum of domesticated and wild C. baccatum germplasm, we utilize AFLP markers to describe the species’ molecular diversity and population structure in the South American
gene pool. Analysis of molecular variance (AMOVA) revealed greater genetic diversity in the wild form of C. baccatum (C. baccatum var. baccatum) than in the domesticated form of the species (C. baccatum var. pendulum). Both Bayesian and distance based clustering analysis, as well as principal coordinates analysis (PCA), concordantly demonstrated
admixture/shared ancestry between wild and cultivated C. baccatum botanical varieties. Two principal genetic groups were identified in the domesticated C. baccatum accessions largely based on their geographic distribution in South America. One group was predominated by accessions from
the western territories of the species’ distribution (Peru, Colombia, Ecuador, Bolivia, Chile and northwestern Argentina)
and the second by accessions from the eastern regions, Paraguay and eastern Argentina). The two genetic groups overlapped
in the geographic location of present-day Bolivia. The grouping pattern suggested that C. baccatum was domesticated in multiple sites and that its evolution took two lineages followed by lineage differentiation. The wild
accessions most closely related to the cultigens were found in the highlands of Peru and Bolivia, which support the early
hypothesis that this region is one of the domestication sites of this species. A Bayesian assignment analysis demonstrated
that Brazilian wild forms of C. baccatum were genetically distant to all other accessions and made little to no contribution to the domesticated genepool. Moreover,
results of clustering analysis suggested that C. baccatum likely originated from present day Paraguay. Analysis of inter-specific relationships across selected Capsicum species supported independent lineages for the two crossability groups within Capsicum, the baccatum species-complex (including C. baccatum) and the annuum species-complex (including C. annuum, C. chinense and C. frutescens). However, the results did not support taxonomic distinction of C. baccatum var. umbilicatum from C. baccatum var. pendulum. The present study provides new insights into the domestication of C. baccatum. The results will be useful for identifying accessions for crop improvement and guiding the development of in situ and ex situ conservation programs. 相似文献
15.