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901.
Song K Nam YJ Luo X Qi X Tan W Huang GN Acharya A Smith CL Tallquist MD Neilson EG Hill JA Bassel-Duby R Olson EN 《Nature》2012,485(7400):599-604
902.
利用天然蛋白质氨基酸序列设计生物仿生材料是近年来兴起的一个热门研究领域.本文中将蚕丝蛋白特征氨基酸序列(Gly-Ala-Gly-Ala-Gly-Ser)部分引入离子互补型多肽RA-DA16-Ⅰ中,设计了新型多肽RAGA16.采用原子力显微镜(AFM)、旋转流变仪(Rheometer)、傅立叶变换红外光谱仪(FTIR)、倒置荧光显微镜等技术对多肽RAGA16的自组装结构、肽链的二级结构、流变学性能以及细胞相容性等进行研究.结果表明,蚕丝蛋白多肽序列引入后,多肽RAGA16具有自组装特性,能够自组装形成致密的纳米级三维网络结构,所形成的水凝胶力学性能明显提高,通过分析得知这可能是由于多肽二级结构中Silk Ⅰ结构成分比例增加所致.荧光染色显示,绝大多数接种于多肽水凝胶中的小鼠前成骨细胞MC3T3-E1能存活,且在不同的三维平面上生长增殖.综上,利用蚕丝蛋白特征序列对RADA16-Ⅰ进行仿生改性后,对拓展多肽材料在生物医学领域的应用具有重要意义. 相似文献
903.
Petrogenesis of Aoyougou high-silica adakite in the North Qilian orogen, NW China: Evidence for decompression melting of oceanic slab 总被引:2,自引:0,他引:2
A trondhjemitic body occurs in the Aoyougou area,the western part of the North Qilian orogen.It is geochemically characterized by high SiO 2,Na 2 O (high Na/K),elevated Sr/Y and (La/Yb) N,positive Sr anomaly,relatively enriched large ion lithophile elements (LILEs) and light rare earth elements (LREEs),and depleted Nb,Ta,Ti,resembling the high-silica adakite.Zircon U-Pb SHRIMP dating yields a weighted mean age of 438±3 Ma.This age is significantly younger than eclogitization ages of 460-490 Ma in the North Qilian orogen,suggesting that formation of the adakite postdates the subduction of oceanic crust in association with closure of the ancient Qilian Ocean.Whole-rock Sr and Nd isotopic analyses give initial ratios of I Sr =0.7044 0.7047 and Nd (t)=3.0 4.1,indicating that they are derived from partial melting of the juvenile oceanic crust.In view of the tectonic evolution of the North Qilian orogen,the high-silica adakite was probably derived from decompression melting of the exhumed eclogite at the depth of ~60 km. 相似文献
904.
MingShan Zhang YunWei Ou HongWei Zhang JunPing Zhang Lei Xia YanMing Qu HaoRan Wang QiMin Zhan YongMei Song ChunJiang Yu 《科学通报(英文版)》2012,57(22):2914-2919
Leptomeningeal metastasis (LM) is caused by the spread of malignant tumor cells into the subarachnoid space.However,classification and staging of LM in the spinal canal is rare in the literature.The authors reviewed the records of 58 Chinese patients with LM for clinical features,neuroimaging,and treatments.Gadolinium-enhanced magnetic resonance imaging (MRI) of brain and spinal cord were performed in all patients.Removal of intracranial tumors was performed in all patients and diagnoses were confirmed by histology.The study group consisted of 58 patients,with 29 cases presenting with intraspinal symptoms.Of the 58,8 patients underwent intraspinal tumor removal,8 received radiotherapy alone,9 received chemotherapy alone,and 34 patients received combined radiochemotherapy.We classified LM into 3 types:type L or leptomeninges LM,is subdivided into 2 subtypes (subtype LI and LII (a,b)),type N or nerve root LM is subdivided into 2 subtypes (subtype NI and NII (a,b)),and type M or mixed-type LM.We also divided LM into stages of I-IV according to the symptoms and the volume of the tumor based on spinal axial MRI.Type LI LM often occurs in patients with intracranial and intraspinal tumors found simultaneously.Patients who receive surgery for intracranial tumors may present with type N LM.Surgery is suitable for patients with NI LM and LIIb LM in stages III-IV,presenting with severe spinal symptoms.The prognosis is better for type N LM than type L LM. 相似文献
905.
In this study, photo-Fenton oxidation was applied to degradation of sulfamonomethoxine sodium (SMMS) in aqueous solution. The operation parameters of pH, temperature, and concentrations of H2O2, Fe2+ and SMMS were investigated. The optimum conditions for the photo-Fenton process were determined as follows: [SMMS]=4.53 mg/L, pH 4.0, [H2O2]=0.49 mmol/L, [Fe2+]= 19.51 μmol/L and T=25°C. Under these conditions 98.5% of the SMMS degraded. The kinetics were also studied, and degradation of SMMS by the photo-Fenton process could be described by first-order kinetics. The apparent activation energy was calculated as 23.95 kJ/mol. Mineralization of the process was investigated by measuring the chemical oxygen demand (COD), and the COD decreased by 99% after 120 min. This process could be used as a pretreatment method for wastewater containing sulfamonomethoxine sodium. 相似文献
906.
907.
文章从审美倾向、表现手法等方面探讨了藏族小说旨在穿越历史探寻规律,挖掘藏民族个体与群体的精神世界及其与宗教文化的关系,着力表现藏族百姓的人性美、藏族英雄的崇高美和青藏高原的神奇美等方面的审美价值以及审美趋向。 相似文献
908.
宋爱国 《首都师范大学学报(自然科学版)》2012,33(2):27-30
提出了平面漫反射板对真空太阳集热管能量采集贡献的计算模型.计算结果表明,在垂直入射光线下,平面漫反射板对真空太阳集热管能量采集的贡献较大,且依其结构因子的不同而不同. 相似文献
909.
利用磁控溅射在250℃的MgO(220)单晶基片上先后沉积Cr(100 nm)下底层和不同厚度(9~80 nm)的Co-11%W(原子分数)磁性层,二者取向附生生长关系为Cr(112)[111]∥Co-W(1010)[1210]和Cr(112)[110]∥Co-W(1010)[0001].随着膜厚的增加,Co-W在薄膜面内的压应变(ε0)从0.781 3%减小到0.544 5%,相应地其有效磁晶各向异性能一级常数Ke1ff由3.82×106减小到2.58×106erg/cc.该结果表明通过设计磁性层和下底层之... 相似文献
910.
以上海市仙霞西路隧道地下穿越虹桥机场绕滑道工程为背景,对其规划设计、施工和运营3个阶段的风险因素及其相互关联性和演化关系进行了分析,并提出了风险演化的概念,在一定程度上实现了机场飞行区穿越工程的全过程风险识别.结果表明,盾构隧道3个阶段之间的风险演化为其风险识别与分析的重要组成部分,在工程设计阶段应对整个工程各阶段的风险因素及其相互演化关系进行分析,并制定应对措施. 相似文献