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151.
A first or dominant immunization with one antigen markedly inhibited specific cytolytic T lymphocyte (CTL) responses to a second unrelated alloantigen without suppressing antibody responses to other antigens. Suppression was induced rapidly, became systemic, and could be transferred passively with only serum. Suppression did not result from elimination of cells capable of responding to the second antigen. The mechanisms responsible for this "priority of the first response" may be the same that help protect the fetus during pregnancy, promote renal allograft survival after multiple blood transfusions, and prevent effective CTL-mediated immunity to variants of tumor cells or infectious agents that arise during tumor progression or chronic infections. 相似文献
152.
Congenital diseases of the equine head 总被引:1,自引:0,他引:1
Many questions concerning heritability arise when a veterinarian is asked to supervise and treat disease of congenital origin. Genetic counseling, ethics, and legality are often confronted in discussions between animal health professionals and laymen in animal industry. Guidelines have been offered as in the 1984 statement of the Judicial Council of the American Veterinary Medical Association: "Performance of surgical procedures in all species for the purpose of concealing genetic defects in animals to be shown, raced, bred, or sold as breeding animals is unethical. However, should the health or welfare of the individual patient require correction of such genetic defects, it is recommended that the patient be rendered incapable of reproduction." The Australian Veterinary Law, Ethics, Etiquette and Convention declares it fraud to alter a defect for sale purposes and unethical for a veterinarian to perform such treatments. It is permissible to correct defects causing discomfort or inconvenience, but the veterinarian is required to advise appropriate breeding counseling. Genetic counseling has progressed significantly in human medicine. This has been supported by better diagnostic methods for genetic disorders, greater acceptance of preventive measures, and extended screening programs to identify carriers of specific abnormal genes or chromosomal aberrations. Congenital diseases in veterinary medicine are constantly under investigation. The veterinary practitioner must continue to operate with an appreciation of the incomplete understanding of most of these abnormalities and act in accordance with personal ethical judgment and the guidance of the American Veterinary Medical Association when treating the affected individual animal patient. 相似文献
153.
JL Fleckenstein D Watumull DD McIntire LA Bertocci DP Chason RM Peshock 《Canadian Metallurgical Quarterly》1993,74(6):2855-2859
We studied the effects of progressive maximal voluntary handgrip contractions (MVCs) on muscle proton spin-spin (T2) relaxation times and work, measured as the integrated force vs. time curve (FTI). Six healthy volunteers performed 10, 20, 40, and 80 MVCs in a 0.35-T magnet on four separate occasions. Repeated measures analyses of variance of increases in T2 and FTI during successive bouts were significant (P < 0.005 and P < 0.001, respectively). FTI increased with successive bouts to a greater extent than did muscle T2 (P < 0.05). For T2, the Helmert contrast judged the 10-MVC response lower than the mean of the remaining responses (P < 0.005), and the differences between all others compared with the means of subsequent responses were not significant, indicating a "flattening" of the T2 response after the increase from 10 to 20 repetitions. For FTI, all the single degree of freedom Helmert contrasts were significant (P < 0.001), indicating a continual increase in response over increased MVCs. The curved nature of the T2 response conformed best to a hyperbolic function, suggesting that a limit of approximately 32% exists for the change in T2 during progressively longer bouts of MVCs. A limit in the T2 response is consistent with the existence of a limit in the amount of water that muscle can take up from the vasculature during exertion. 相似文献
154.
铬、钴、铁用作彩色渗花砖发色元素的研究 总被引:1,自引:0,他引:1
用晶体体场理论讨论了铬、钴、铁作为陶瓷发色元素的呈色机理,并对彩色渗花液在砖坯上的渗入过程及物理化学原理进行了研究,分析了影响发色剂呈色的主要因素。 相似文献
155.
The per review system for the assessment of research proposals is widely respected by working scientists. Nevertheless two problems associated with the operation of this system by the US National Institutes of Health are identified. First the scientist has no control over which committee will review an application and it may be considered by a quite inappropriate group. Second analysis of the committee composition suggests that in some of the groups several members are not active scientists and therefore not the "peers" of the applicant. 相似文献
156.
工艺参数对TiO2碳热还原合成Ti(C,N)粉末的影响 总被引:4,自引:0,他引:4
本文探讨了TiO2碳热还原法合成Ti(C,N)粉末过程中合成温度,保温时间,N2气流量,C/Ti比值等工艺参数的变化对粉末性状的影响,实验表明,N比C更易于Ti结合,改变工艺对数可调整Ti(C1-xNx)的x值。在1400~1700℃间可获得x值的0.6~0.85的Ti(C1-xNx)粉末。 相似文献
157.
Shikai Jing Lianbo Ma Kunyuan Hu Yunlong Zhu Hanning Chen 《Journal of Intelligent Manufacturing》2018,29(1):109-134
For printable electronics fabrication, a major challenge is the print resolution and accuracy delivered by a drop-on-demand piezoelectric inkjet printhead. In order to meet the challenging requirements of printable electronics fabrication, this paper proposes a novel restructured artificial bee colony optimizer called HABC for optimal prediction of the droplet volume and velocity. The main idea of HABC is to develop an adaptive and cooperative scheme by combining life-cycle, Powell’s search and crossover-based social learning strategies for complex optimizations. HABC is a more biologically-realistic model that the reproduce and die dynamically throughout the foraging process and the population size varies as the algorithm runs. With the crossover operator, the information exchange ability of the bees can be enhanced in the early exploration phase while the Powell’s search enables the bees deeply exploit around the promising area, which provides an appropriate balance between exploration and exploitation. The proposed algorithm is benchmarked against other four state-of-the-art bio-inspired algorithms using both classical and CEC2005 test function suites. Then HABC is applied to predict the printing quality using nano-silver ink. Statistical analysis of all these tests highlights the significant performance improvement due to the beneficial combination and shows that the proposed HABC outperforms the reference algorithms. 相似文献
158.
Silicon - Al-Si based alloy matrix composites are now broadly utilized by the industrial sectors like automobile, structural, aerospace and more practical industrial applications due to its... 相似文献
159.
160.
Lieffers JR Hanning RM 《Revue canadienne de la pratique et de la recherche en diététique》2012,73(3):142
Nutrition applications for mobile devices (e.g., personal digital assistants, smartphones) are becoming increasingly accessible and can assist with the difficult task of intake recording for dietary assessment and self-monitoring. This review is a compilation and discussion of research on this tool for dietary intake documentation in healthy populations and those trying to lose weight. The purpose is to compare this tool with conventional methods (e.g., 24-hour recall interviews, paper-based food records). Research databases were searched from January 2000 to April 2011, with the following criteria: healthy or weight loss populations, use of a mobile device nutrition application, and inclusion of at least one of three measures, which were the ability to capture dietary intake in comparison with conventional methods, dietary self-monitoring adherence, and changes in anthropometrics and/or dietary intake. Eighteen studies are discussed. Two application categories were identified: those with which users select food and portion size from databases and those with which users photograph their food. Overall, positive feedback was reported with applications. Both application types had moderate to good correlations for assessing energy and nutrient intakes in comparison with conventional methods. For self-monitoring, applications versus conventional techniques (often paper records) frequently resulted in better self-monitoring adherence, and changes in dietary intake and/or anthropometrics. Nutrition applications for mobile devices have an exciting potential for use in dietetic practice. 相似文献