A specific requirement for PDGF-C in palate formation and PDGFR-alpha signaling

PDGF-C is a member of the platelet-derived growth factor (PDGF) family, which signals through PDGF receptor (PDGFR) alphaalpha and alphabeta dimers. Here we show that Pdgfc(-/-) mice die in the perinatal period owing to feeding and respiratory difficulties associated with a complete cleft of the secondary palate. This phenotype was less severe than that of Pdgfra(-/-) embryos. Pdgfc(-/-) Pdgfa(-/-) embryos developed a cleft face, subepidermal blistering, deficiency of renal cortex mesenchyme, spina bifida and skeletal and vascular defects. Complete loss of function of both ligands, therefore, phenocopied the loss of PDGFR-alpha function, suggesting that both PDGF-A and PDGF-C signal through PDGFR-alpha to regulate the development of craniofacial structures, the neural tube and mesodermal organs. Our results also show that PDGF-C signaling is a new pathway in palatogenesis, different from, and independent of, those previously implicated.     

用建构主义教学模式革新高校地理课程教学势在必行

指出人类社会的教学过程已经历了师徒教学模式和课堂教学模式两次变革 ,随着电子媒体的产生与应用 ,建构主义教学模式必将取代传统的课堂教学模式 .认为我国高校地理课程教学不但适应建构主义教学模式 ,而且已具有一定的技术与物质基础 ,用建构主义教学模式革新高校地理课程教学势在必行     

"软工程"战略与西北干旱半干旱区水资源的合理利用

在简述了西北干旱半干旱区水资源特点与问题的基础上,分析了水资源浪费的主要原因,提出了水资源合理利用的“软工程”战略及其具体措施,强调从改善水资源环境,建立节水型社会及治理水土流失等方面来利用与配置干旱半干旱区的水资源。     

Paxillin binds schwannomin and regulates its density-dependent localization and effect on cell morphology

Neurofibromatosis type 2 is an autosomal dominant disorder characterized by tumors, predominantly schwannomas, in the nervous system. It is caused by mutations in the gene NF2, encoding the growth regulator schwannomin (also known as merlin). Mutations occur throughout the 17-exon gene, with most resulting in protein truncation and undetectable amounts of schwannomin protein. Pathogenic mutations that result in production of defective schwannomin include in-frame deletions of exon 2 and three independent missense mutations within this same exon. Mice with conditional deletion of exon 2 in Schwann cells develop schwannomas, which confirms the crucial nature of exon 2 for growth control. Here we report that the molecular adaptor paxillin binds directly to schwannomin at residues 50-70, which are encoded by exon 2. This interaction mediates the membrane localization of schwannomin to the plasma membrane, where it associates with beta 1 integrin and erbB2. It defines a pathogenic mechanism for the development of NF2 in humans with mutations in exon 2 of NF2.     

用有限元的结构分析：第二版

有限元法已经成为结构分析中必不可少的工具，并创造了前所未有的成功历史。本书从结构分析的观点来论述有限元法的基础知识，并讨论在用有限元法来模拟结构时所产生的问题，例如：为什么有限元的结果是错的？     

西藏芒康县盐井化探异常分布规律及找矿标志

盐井属于藏东昌都地区芒康县,地处于著名的三江成矿区;藏东地质构造复杂,成矿条件优越,具备形成铜、金、铅、锌、银矿的地质背景,是中国重要的多金属成矿带。根据1∶20万区域化探异常特征优选了芒康县盐井开展1∶5万地球化学测量,Au、Cu、Ag、Pb元素套叠好,异常强度大,属于典型的矿致异常,找矿前景十分广阔,是该区重要找矿靶区。     

框筒结构剪力滞后效应分析

剪力滞后现象是高层框筒结构的一个重要力学现象,本文采用能量变分法分析了薄壁箱形截面梁的剪力滞后效应,对影响剪力滞系数的几何参数进行了对比分析,得到了一些有用的结论,对结构设计与施工有一定的指导作用.     

试论教学方法改革的发展趋向

介绍了目前教学方法改革的基本特征,分析了教学方法改革的发展趋向,旨在有助于教学方法的深入改革和教学水平的进一步提高.     

烯烃气相色谱保留指数的预测

通过对部分烯烃在不同固定相不同柱温下的1031个样本集的气相色谱保留指数值(RI)与其部分参数关系的研究,发现RI与拓扑指数(mQ)、双键原子杂化状态指数(DHSI)、支链对双键的极化效应指数(PBD)、固定液极性值(CP)及柱温(T)的关系可表示为:^RI=-58.138 57.7460Q-8.2591Q 0.120T 0.807CP 36.460PBD 7.919DHSI(R=0.9989)继以留一法(Leave-one-out,LOO)进行交互检验,相关系数RCV=0.9977,说明所建模型具有良好的稳定性和预测能力,较好地揭示了烯烃类化合物气相色谱保留指数RI随固定相极性、柱温的改变而变化的规律.     

存储区域网功能的研究

随着网络基础建设的快速发展,网络存储由于其自身的优点正得到越来越广泛的应用.本文从存储区域网的特点及其功能方面介绍了存储区域网络技术.