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排序方式: 共有494条查询结果,搜索用时 15 毫秒
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Transportation of energy and substances is fundamental for the conditions of life. The energy from metabolised food is yielded at the reduction of oxygen by the assistance of Se-enzymes. Activated Se-enzymes contain an electron conducting Se-link with elemental Se bounded to Se-cys (Se-cystein) that prevents electron transferring (autoxidable) agents, as arginine, from oxidations. NO is formed from e.g. arginine during the passive state of a Se-enzyme. With NO, instead of O2, bounded to a hem group, destroying oxidations are avoided. This is the role of NO. A nerve signal is activated by the GTP (guanosine triphosphate)-induced triggered transformation of cGMP (cyclic guanosine monophosphate) into GMP, closing the sodium channels. When GTP is consumed, the opposite reaction takes place. The direct influence of the GMP/cGMP quote on a nerve signal makes GMP/cGMP equal to EDHF (endothelium-derived hyperpolarizing factor). Part of the energy from food is stored and transported in the form of acetyl groups, building up many important molecules of which LDL (low density lipoprotein) is one, containing cholesteryl esters. These are brought in to the cell, decomposed to acetyl groups generating hydrogen, H, making LDL to an essential substance. High levels are connected to impaired energy yielding reactions, perhaps related to low levels of some substances, especially to one or both forms of Se. The necessity of a Se-link and NO induced protection against oxidations by reducible oxygen can no longer be neglected. 相似文献
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Emulsifying salts and hydrocolloids, cook time, cook temperature, and pH were evaluated to characterize their effects on firmness, meltability, and spreadability of fat‐free process‐cheese spreads. Disodium phosphate and trisodium citrate produced properties closest to those of a full‐fat reference cheese, with trisodium citrate providing the most meltability. In all cases, incorporation of hydrocolloids resulted in increased firmness, decreased melt, with varying results on spreadability. Increases in cook time generally produced softer, more meltable cheeses, while increases in cook temperature decreased firmness and increased meltability and spreadability. 相似文献
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执行器失效不确定时滞系统的指定衰减度鲁棒可靠控制 总被引:8,自引:0,他引:8
针对一类含有时变时滞的不确定参数线性系统,研究了在执行器发生故障情况下的鲁棒可靠控制器设计问题.系统中的参数不确定性满足广义匹配条件,时变时滞的大小及其变化率有界,并假设故障执行器元件的输出为零.经过适当的模型变换,将原系统的鲁棒指数镇定问题转化为另一个等价系统的鲁棒镇定问题.根据Lyapunov稳定性理论和线性矩阵不等式(LMI)方法,分别给出了鲁棒可靠控制器存在的时滞无关和时滞相关充分条件.仿真结果表明了该控制器设计方法的有效性. 相似文献
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Several studies have suggested that if a calf vein thrombosis does not propagate above the knee when followed up with serial diagnostic studies, full anticoagulation may not be necessary. These studies have not included spinal cord injured patients. Two patients with spinal cord injury were diagnosed with acute calf vein thrombosis after admission to a spinal cord injury rehabilitation unit. Both patients refused intravenous heparinization. Serial duplex Doppler studies were performed on both patients to evaluate for propagation of thrombus. Neither patient developed propagation of thrombus, pulmonary embolus, or persistent thrombophlebitis. Full anticoagulation including intravenous heparinization is costly, subject to complications, and interferes with intensive rehabilitation therapies. Observation of calf vein thrombosis with appropriate serial follow-up studies may be a viable alternative to anticoagulation in spinal cord injured patients. Further studies need to be done with this unique patient population. 相似文献
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