不同灭菌方法对小鼠饲料表观消化率影响的初步研究

对几种不同灭菌方法处理的饲料用于小鼠表观消化率试睑,初步结果表明:经γ射线灭菌的小鼠饲料,其干物质、粗蛋白、粗脂肪、粗纤维的表观消化率与正常鼠料(未经灭菌处理)相比,无显著差异(P>0.05);经高压蒸汽灭菌的鼠料,其粗脂肪、粗纤维的表现消化率,与正常料相比,无显著差异(P>0.05),但粗蛋白及干物质的表观消化率则显著低于正常料(P<0.01)。三种不同高压蒸汽灭菌方法中,抽真空126℃10分钟灭菌的鼠料,其粗蛋白的表观消化率最高,不抽真空121℃、30分钟灭菌的鼠料,其粗蛋白的表观消化率最低,二者有显著性差异(0.01相似文献   

大型局域网干线流量的可预测性分析

用一种新的算法 ,在校园网的环境下对局域网干线流量的可预测性进行了全面的分析后得出结论 :在时间粒度较细的情况下网络流量的可预测性较好 ,而在 10min以上时间粒度下网络流量基本不具备可预测性 .对分析结果给出简单的理论上的解释     

P2X receptors as cell-surface ATP sensors in health and disease

P2X receptors are membrane ion channels activated by the binding of extracellular adenosine triphosphate (ATP). For years their functional significance was consigned to distant regions of the autonomic nervous system, but recent work indicates several further key roles, such as afferent signalling, chronic pain, and in autocrine loops of endothelial and epithelial cells. P2X receptors have a molecular architecture distinct from other ion channel protein families, and have several unique functional properties.     

Acetylcholine hyperpolarizes central neurones by acting on an M2 muscarinic receptor

Acetylcholine (ACh) is considered to act as a neurotransmitter in the mammalian brain by binding to membrane receptors and bringing about a change in neurone excitability. In the case of muscarinic receptors, cell excitability is usually increased; this effect results from a closure of membrane potassium channels in cortical cells. However, some central neurones are inhibited by ACh, and we hypothesized that these two opposite effects of ACh resulted from interactions with different subtypes of muscarinic receptor. We made intracellular recordings from neurones in the rat nucleus parabrachialis, a group of neurones in the upper pons some of which themselves synthesize ACh. ACh and muscarine caused a membrane hyperpolarization which resulted from an increase in the membrane conductance to potassium ions. The muscarinic receptor subtype was characterized by determining the dissociation equilibrium constant (KD) for pirenzepine during the intracellular recording; the value of approximately 600 nM indicates a receptor in the M2 class. This muscarinic receptor is quite different from that which brings about a decrease in potassium conductance in other neurones, which has a pirenzepine KD of approximately 10 nM (M1 receptors). It is possible that antagonists selective for this kind of M2 receptor would be useful in the management of conditions, such as Alzheimer's disease, which are associated with a reduced effectiveness of cholinergic neurones.     

电梯群控系统的活动扫描法仿真

本文在对电梯群控系统进行分析的基础上，给出了该系统的一种仿真模型。进一步论述了用活动扫描法对该系统进行仿真的原理和步骤。最后以一个例子说明了该方法的可行性。