玉屏风口服液多糖特征降解谱的建立和应用

建立了玉屏风口服液多糖(YPF-P)的特征降解谱,并基于此完善该制剂的质量控制,通过体积分数70%乙醇溶液沉淀得到YPF-P,同时去除口服液中的辅料蔗糖.优化的YPF-P部分降解条件为0.5 mol/L盐酸溶液,温度80 ℃,时间4 h,随后采用毛细管区带电泳法(CZE)对经过1-苯基-3-甲基-5-吡唑啉酮(PMP)衍生后的YPF-P部分降解产物进行测定.CZE条件为未涂层熔融石英毛细管柱(50 cm × 50 μm i.d.,有效长度41 cm),运行缓冲液40 mmol/L硼砂缓冲液(pH 10.1),检测波长245 nm,运行电压10 kV,重力进样15 cm × 20 s,柱温为室温.根据L₉(3⁴)正交设计组合不同来源的玉屏风处方药材,制备9份玉屏风模拟样品,采用中位数法综合各特征降解谱得到YPF-P特征降解谱对照谱图,并对不同批次样品YPF-P特征降解谱进行聚类分析.结果表明:不同来源和组合的YPF-P特征降解谱差异显著,证明多糖特征降解谱可用于YPF-P成分的分析,也可为其他中药复方制剂多糖成分质量控制的深入研究提供参考.     

对高校图书馆临时工聘用与素质提升的思考——以湖南工业大学图书馆为例

阐述了高校图书馆招聘临时工的必要性,指出了图书馆临时工聘用中存在的问题,提出了改进图书馆临时工聘用与提升临时工素质的建议.     

Natural selection and adaptive evolution of leptin

Leptin is an adiposity-secreted hormone that is pivotal in regulating feeding behavior,energy metabolism and body mass.The study of leptin has been of crucial importance for public health and pharmaceutical intervention given its role in obesity.Generally,leptin is highly conserved due to its functional importance.However,episodes of rapid sequence evolution and positive selection have been observed in some mammalian species,indicating that the leptin functions in these animals may have undergone adaptive modification to their environments.In this article,we review the adaptive evolution of leptin and its potential functional consequences.This review is expected to guide future research of molecular evolution and functional assays of this gene,and also to provide a theoretical foundation for the use of leptin in therapeutic applications.     

Swelling Studies of Chitosan-Gelatin Films Cross-Linked by Sulfate

0　IntroductionChitosanisadeacetylatedderivativeofchitin ,containinginitsstructure glucosamineandacetylglucosamine joinedthroughβ (1→ 4 )linkages.ItisinsolubleinwaterandcommonorganicsolventsbutsolubleatapHunder 6 .5acidicmedia.Duetoitsexcellentbiodegradableandbiocompatiblecharacter,chi tosanhasbeenexaminedextensivelyinthepharmaceuticalindus tryforitspotentialinthedevelopmentofdrugdeliverysys tems[1 ,2 ] .Gelatinisabiodegradablepolymerofwidesafety ,pro ducedfromcollagen ,themostabundantprote…     

人工修复盾构姿态错误的测量方法与精度探讨

在盾构掘进过程中,由于施工或导向系统发生故障等原因导致盾构姿态错误时,必须采用人工测量盾构姿态的方法对导向系统进行修复。文中就人工姿态测量原理和计算方法进行了分析,提出了人工修复盾构姿态的方法并分析了方法预期达到的精度,同时结合工程实践分析了该方法对姿态的影响。     

Repetitive motor learning induces coordinated formation of clustered dendritic spines in vivo

Many lines of evidence suggest that memory in the mammalian brain is stored with distinct spatiotemporal patterns. Despite recent progresses in identifying neuronal populations involved in memory coding, the synapse-level mechanism is still poorly understood. Computational models and electrophysiological data have shown that functional clustering of synapses along dendritic branches leads to nonlinear summation of synaptic inputs and greatly expands the computing power of a neural network. However, whether neighbouring synapses are involved in encoding similar memory and how task-specific cortical networks develop during learning remain elusive. Using transcranial two-photon microscopy, we followed apical dendrites of layer 5 pyramidal neurons in the motor cortex while mice practised novel forelimb skills. Here we show that a third of new dendritic spines (postsynaptic structures of most excitatory synapses) formed during the acquisition phase of learning emerge in clusters, and that most such clusters are neighbouring spine pairs. These clustered new spines are more likely to persist throughout prolonged learning sessions, and even long after training stops, than non-clustered counterparts. Moreover, formation of new spine clusters requires repetition of the same motor task, and the emergence of succedent new spine(s) accompanies the strengthening of the first new spine in the cluster. We also show that under control conditions new spines appear to avoid existing stable spines, rather than being uniformly added along dendrites. However, succedent new spines in clusters overcome such a spatial constraint and form in close vicinity to neighbouring stable spines. Our findings suggest that clustering of new synapses along dendrites is induced by repetitive activation of the cortical circuitry during learning, providing a structural basis for spatial coding of motor memory in the mammalian brain.     

Accumulation of a heat shock-like protein during differentiation of human erythroid cell line K562

The human erythroid cell line K562 provides a model system for studying erythroid differentiation and eukaryotic gene regulation. These cells express glycophorin A, spectrin and i antigen. They accumulate embryonic and fetal haemoglobins on induction of erythroid differentiation with haemin, sodium butyrate or hydroxyurea. In the present study, the protein composition of K562 cells during haemin-mediated induction of erythroid maturation was analysed by two-dimensional gel electrophoresis. Under conditions in which haemin did not effect cell viability and proliferation, a protein of approximately 70,000 molecular weight (MW) accumulated in the differentiated K562 cells. The accumulation appears to be due to an increase in the rate of RNA synthesis for this protein. The protein is related in sequence to a 70,000-MW heat shock protein. An antigenically related protein was also demonstrated in human bone marrow and accumulates at particular stages of human erythroid maturation.     

新形势下美国对华科技竞争战略的特点、走向与应对 ——基于美国重点智库报告的分析

随着中美科技竞争日益加剧,美国对华科技竞争战略的特点和走向备受关注.首先,结合拜登及核心对华团队的政策主张,总结出其科技竞争战略具有"追求美国领先、重返多边体系、注重意识形态和聚焦有限目标"四大基本特点.其次,结合美国相关重点智库研究报告,研判美国对华科技竞争战略走向具体呈现3个方面,即以"小院高墙"为原则的技术保护、...