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1.
陈绍钢 《中国农村水利水电》2000,(1):31-33
根据已有的使用情况，从水轮机顶盖取水作为机组技术供水源存在着一些问题，为此，从止漏环间隙及顶盖取水的水量和水压，顶盖取水管和稳压池的布置，顶盖取水的运行方式及注意事项等方面，探讨了中小型水轮机从顶盖取冷却水的可行性、经济效益及注意事项。 相似文献
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Suckling both, or only one contralateral mammary gland during 15 days postpartum was utilized to study lactogenic hormone binding to mammary microsomal membranes and quantitative mammary morphology in ewes. Binding of radiolabeled human growth hormone was specific for lactogenic hormones. Non-radiolabeled human growth hormone, ovine and bovine prolactin and human placental lactogen effectively competed with radiolabeled human growth hormone for binding sites but ovine and bovine growth hormone were completely ineffective. Specific binding of radiolabeled human growth hormone to 600 μg of membrane protein averaged 23 ± 3% in all lactating glands. Neither days postpartum nor treatment of contralateral mammary glands substantially altered hormone binding in lactating glands. Specific human growth hormone binding (6 ± 0.5%) in non-suckled glands (15 days postpartum both udder halves) was significantly lower (P<0.01) than in lactating tissue but only a moderate and variable reduction in specific binding was measured in membranes from glands non-suckled for 15 days but contralateral to a suckled gland (14 ± 4%). Specific binding was approximately doubled in assays with 600 compared with 300 μg of membrane protein and the pattern of binding among variously suckled glands was not changed by treatment of membranes with 4 M MgCl2 prior to assay. Most secretory cells from all lactating glands had rounded, basally displaced nuclei, apical fat globules, secretory vesicles and abundant densely stained basal cytoplasm (ergastoplasm). Alveolar lumenal area was maximal (50% of tissue area) and stromal tissue area was minimal. After 15 days of non-suckling (both udder halves) mammary cells were engorged with lipid, ergastoplasm was reduced and nuclei were irregularly shaped and randomly displaced compared with lactating tissue. In addition, lumenal area was reduced and stromal tissue more evident. Lack of suckling for 5 days had little apparent effect on mammary cytology. Like lactogenic hormone binding, mammary tissue morphology was only moderately altered by 15 days of non-suckling when the remaining gland was suckled. RNA concentration was lowest (2.1 ± 0.3 mg/g) in mammary tissue from ewes in which neither gland was suckled for 15 days postpartum but non-suckling interval had no significant effect when contralateral glands were suckled. DNA concentration was not significantly influenced by suckling treatments. Relative lactogenic hormone binding closely corresponded to changes in cytological and biochemical indices of secretory cell function. 相似文献
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如何防范与应对ARP病毒现已成为摆在各校园网网络管理者面前的一个厄待解决的技术难题。本文阐述了ARP协议工作的原理，分析了ARP病毒攻击过程，剖析了ARP病毒对网络的危害，并结合校园网络的架构特点给出了ARP病毒防范与应对的方法。 相似文献
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Diane Murdaugh DVM PhD Richard I. Miller BVSc PhD David R. Harrington DVM Louis L. Martin DVM 《Journal of Equine Veterinary Science》1985,5(4):189-191
An in utero tibial fracture was examined at necropsy in a seven-month-old male aborted Thoroughbred fetus. Grossly the healed fracture had a smooth cortical surface. Histologically there was no callus formation or excessive osteoclastic or osteoblastic activity. 相似文献
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Animal surveys were conducted in six habitat types within the timber concession of PT International Timber Corporation Indonesia, East Kalimantan. Species diversity was found to be similar in undisturbed forest and in 3- to 5-year-old selectively logged forest, although densities in the latter were considerably less. Both diversity and density declined drastically in forestry plantations, but certain of the species remaining caused significant damage to young trees. Although few animals were observed in areas where there was active road construction and timber felling, their densities in adjacent undisturbed forest areas did not increase, suggesting that the level of local migration actually is low. It is suggested that recolonisation of old logged forest can occur successfully provide that the level of hunting is low and that adjacent areas of undisturbed forest remain to provide a population pool from which colonists can spread. 相似文献
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Isolation of Pasteurella haemolytica and correlation with serum antibody response in clinically normal beef calves 总被引：1，自引：0，他引：1
Bacteria from the nasal cavity and trachea were cultured, and serum antibody titers determined for Pasteurella haemolytica serotype 1 in 164 beef calves obtained from a closed herd on range pasture. At the first sampling, P. haemolytica serotype 1 was cultured from 16.4% of the calves. Antibody titers were determined by a quantitative fluorimetric method and the mean titer was 9.5 +/- 5.8. Fifty-seven randomly selected calves were used to study the correlation of serum antibody response and positive culture of P. haemolytica under natural conditions. Clinical signs of respiratory disease were not observed in those calves. During the observation periods, there was a two-fold increase in the percentage of calves that were culture positive. There was no significant difference between mean serum antibody titers or frequency distribution of antibody titers from the two samplings. Comparisons between serum antibody titers, rise in titers, and P. haemolytica isolation failed to reveal any significant correlation. Of the 9 calves that had a decline in antibody titer to P. haemolytica, none was culture positive. Seroconversion to respiratory viruses did not correlate with P. haemolytica related variables. 相似文献
7.
D L Knudson W K Butterfield R E Shope T E Walton C H Campbell 《Veterinary microbiology》1982,7(4):285-293
The genomes of U.S. bluetongue viruses, an Australian bluetongue virus, and three other related orbiviruses were analyzed by polyacrylamide gel electrophoresis. The genomes were comprised of ten segments of double-stranded (ds) RNA. Estimates of the molecular weights of the dsRNA segments revealed that the U.S. bluetongue serotypes were remarkably similar. Although the dsRNA profiles of the viruses exhibited common segments, each virus had a distinct dsRNA profile. The usefulness of the genome analysis as a diagnostic tool for identification and for epidemiologic studies is discussed. 相似文献
8.
The objective of this study was to determine the optimal conditions for the short term incubation of chicken granulosa cells. Compared to mechanically-dispersed cells, collagenase-treatment yielded granulosa cells of greater viability and responsiveness to ovine LH (oLH) stimulation. The rate of progesterone secretion by enzyme-dispersed chicken granulosa cells was subsequently compared in five different culture media during incubation periods of up to 24 hr. Under room air as the gas phase, Medium 199 (M199) containing Hank's salts and Ham's F-12 medium (F-12) were the most effective, whereas Krebs-Ringer bicarbonate-buffered glucose solution (KRBG) and Dulbecco's medium were the poorest. When pH and the ionic strength of KRBG was maintained by continuous gassing with O2:CO2 (95:5), progesterone production was similar to that obtained with Hepes-buffered M199. The pH optimum was found to be 7.4, although within the range of 6.6–8.5 granulosa cells remained responsive to LH stimulation. The optimal cell density was observed to be 1 × 104 to 5 × 105/ml. Although time course studies showed that both basal and stimulated progesterone production peaked by about 12 hr of incubation regardless of the media composition, the amounts released were significantly greater in M199 and F-12 during more prolonged (up to 24 hr) incubations. Glucose, a key medium ingredient for hormone-stimulated steroidogenesis, could be replace by pyruvate. On the other hand, lactate was inhibitory. It is concluded that the mature ovarian follicles of the domestic fowl are an excellent source of pure granulosa cells that can be obtained in high yield after a brief treatment with collagenase. These cells remain viable up to 24 hr and continue to produce large amounts of progesterone in response to LH when incubated in an appropriate medium and at optimal cell density. 相似文献
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