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A veterinarian desiring to increase his or her proficiency in canine reproduction needs to become competent in a variety of reproductive procedures. This article describes commonly performed procedures and gives an overview of how to develop a practice in canine reproduction. Once a veterinarian develops expertise in this area, the base of breeder clients in the practice should rapidly increase.  相似文献   
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A 3-month-old English Bulldog had excretory incontinence and sensory deficits in the distribution of pudendal nerves. Noncontrast radiography, myelography, and computed tomography revealed spina bifida beginning at L7, an expanded subarachnoid space caudal to L7, and a taut, thick filum terminale. Microsurgical exploration of the lumbosacral spine confirmed the presence of a tethered cord, and the filum terminale was transected. The spinal cord immediately migrated cranially about 1 cm. Although some sensory improvement was evident during a 2-week postoperative period, the dog was euthanatized. Postmortem examination confirmed spina bifida and atrophy of sacral nerve roots and perineal muscles, thoracic hemivertebrae, and hydrocephalus.  相似文献   
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INDEPTH geophysical and geological observations imply that a partially molten midcrustal layer exists beneath southern Tibet. This partially molten layer has been produced by crustal thickening and behaves as a fluid on the time scale of Himalayan deformation. It is confined on the south by the structurally imbricated Indian crust underlying the Tethyan and High Himalaya and is underlain, apparently, by a stiff Indian mantle lid. The results suggest that during Neogene time the underthrusting Indian crust has acted as a plunger, displacing the molten middle crust to the north while at the same time contributing to this layer by melting and ductile flow. Viewed broadly, the Neogene evolution of the Himalaya is essentially a record of the southward extrusion of the partially molten middle crust underlying southern Tibet.  相似文献   
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Radio tracking data from the Viking lander have been used to determine the lander position and the orientation of the spin axis of Mars. The areocentric coordinates of the lander are 22.27 degrees N, 48.00 degrees W, and 3389.5 kilometers from the center of mass; the spin axis orientation, referred to Earth's mean equator and equinox of 1950.0, is 317.35 degrees right ascension and 52.71 degrees declination.  相似文献   
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Secretory and membrane proteins carry amino-terminal signal sequences that, in cotranslational targeting, are recognized by the signal recognition particle protein SRP54 without sequence specificity. The most abundant membrane proteins on Earth are the light-harvesting chlorophyll a/b binding proteins (LHCPs). They are synthesized in the cytoplasm, imported into the chloroplast, and posttranslationally targeted to the thylakoid membrane by cpSRP, a heterodimer formed by cpSRP54 and cpSRP43. We present the 1.5 angstrom crystal structure of cpSRP43 characterized by a unique arrangement of chromodomains and ankyrin repeats. The overall shape and charge distribution of cpSRP43 resembles the SRP RNA, which is absent in chloroplasts. The complex with the internal signal sequence of LHCPs reveals that cpSRP43 specifically recognizes a DPLG peptide motif. We describe how cpSPR43 adapts the universally conserved SRP system to posttranslational targeting and insertion of the LHCP family of membrane proteins.  相似文献   
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Measurements of the frequency, phase, and amplitude of the S-band radio signal of Mariner V as it passed behind Venus were used to obtain the effects of refraction in its atmosphere and ionosphere. Profiles of refractivity, temperature, pressure, and density in the neutral atmosphere, as well as electron density in the daytime ionosphere, are presented. A constant scale height was observed above the tropopause, and the temperature increased with an approximately linear lapse rate below the tropopause to the level at which signal was lost, presumably because heavy defocusing attenuation occurred as critical refraction was approached. An ionosphere having at least two maxima was observed at only 85 kilometers above the tropopause.  相似文献   
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