雪灵芝水溶性多糖提取工艺优化及其数学模型的建立

目的 优化雪灵芝水溶性多糖的提取工艺,并建立数学模型.方法 采用水提醇沉法提取雪灵芝水溶性多糖;运用苯酚-硫酸法测定多糖含量;通过单因素实验研究浸提时间、加水比、浸提温度及乙醇浓度对多糖提取率的影响;采用响应面分析法优化提取条件,运用sas软件分析实验数据,建立回归模型.结果 得到雪灵芝水溶性多糖提取的优化工艺参数的最佳取值范围为:浸提温度(94.5～97.5℃);浸提时间(2～2.5h);加水比(43～51v/w).结论 为雪灵芝水溶性多糖提取工艺的优化提供了一定的技术依据,也为其后续研究奠定了基础.     

不完全市场下有违约风险的欧式期权定价

为了研究不完全市场对有违约风险欧式期权定价的影响,结合Klein的有违约风险期权处理方法和Cochrane与Saa-Requejo的不完全市场处理方法给有违约风险的欧式期权定价,得到不完全市场下有违约风险欧式期权的一般化定价公式.进一步推导出一些特定欧式期权的定价公式,并指出这些公式均为一般化定价公式的特例.结果表明定价公式结合了上述两个模型的优点,因此特别适合于给基于不可交易资产有违约风险期权定价.     

Wnt-beta-catenin signaling initiates taste papilla development

Fungiform taste papillae form a regular array on the dorsal tongue. Taste buds arise from papilla epithelium and, unusually for epithelial derivatives, synapse with neurons, release neurotransmitters and generate receptor and action potentials. Despite the importance of taste as one of our five senses, genetic analyses of taste papilla and bud development are lacking. We demonstrate that Wnt-beta-catenin signaling is activated in developing fungiform placodes and taste bud cells. A dominant stabilizing mutation of epithelial beta-catenin causes massive overproduction of enlarged fungiform papillae and taste buds. Likewise, genetic deletion of epithelial beta-catenin or inhibition of Wnt-beta-catenin signaling by ectopic dickkopf1 (Dkk1) blocks initiation of fungiform papilla morphogenesis. Ectopic papillae are innervated in the stabilizing beta-catenin mutant, whereas ectopic Dkk1 causes absence of lingual epithelial innervation. Thus, Wnt-beta-catenin signaling is critical for fungiform papilla and taste bud development. Altered regulation of this pathway may underlie evolutionary changes in taste papilla patterning.     

Chronobiology of sleep in humans

Periodic circadian (24-h) cycles play an important role in daily hormonal and behavioural rhythms. Usually our sleep/wake cycle, temperature and melatonin rhythms are internally synchronized with a stable phase relationship. When there is a desynchrony between the sleep/wake cycle and circadian rhythm, sleep disorders such as advanced and delayed sleep phase syndrome can arise as well as transient chronobiologic disturbances, for example from jet lag and shift work. Appropriately timed bright light is effective in re-timing the circadian rhythm and sleep pattern to a more desired time, ameliorating these disturbances. Other less potent retiming effects may also be obtained from the judicious use of melatonin and exercise.     

京津冀联合发展以应对外强

介绍了京津冀联合发展的巨大潜力,分析了京津冀联合发展的优势,探讨了京津冀联合发展的对策。     

ADO意义.NET在并发控制方面存在的问题及解决方案

针对ADO.NET在处理"丢失的修改"问题时,不支持"关键字和已修改字段"的并发控制问题提出了相应的解决办法;同时对ADO.NET架构本身带来的异常更新问题提供了解决思路.     

Structural Changes of Water Molecules Upon the Reduction of Quinones in The Reaction Center from Rhodobactery Sphaeroides

1 Results The photosynthetic bacterial reaction center (RC) is a membrane protein complex.The RC is composed of three protein subunits and redox components such as bacteriochlorophylls, bacteriopheophytins,and quinones.The RC performs the photochemical electron transfer from the bacteriochlorophyll dimer through a series of electron donor and acceptor molecules to a secondary quinone,QB.QB accepts electrons from a primary quinone,QA,in two sequential electron transfer reactions.The second electron trans...