Si(111)衬底无微裂GaN的MOCVD生长

采用AlN插入层技术在Si(111)衬底上实现无微裂GaN MOCVD生长.通过对GaN外延层的a,c轴晶格常数的测量,得到了GaN所受张应力与AlN插入层厚度的变化关系.当AlN厚度在7～13nm范围内,GaN所受张应力最小,甚至变为压应力.因此,GaN微裂得以消除.同时研究了AlN插入层对GaN晶体质量的影响,结果表明,许多性能相比于没有AlN插入层的GaN样品有明显提高

中国脑血管病临床管理指南（第2版）（节选）——第4章 缺血性脑血管病临床管理推荐意见 Chinese Stroke Association Guidelines for Clinical Management of Cerebrovascular Diseases (Second Edition) (Excerpt)——Chapter Four Clinical Management of Ischaemic Cerebrovascular Diseases

我国的卒中发病率仍在持续上升，每年新发病例占全球的四分之一。在我国40岁及以上的人群中，缺血性卒中约占所有卒中类型的86.8%。自2019年中国脑血管病临床管理指南发布以来，缺血性卒中急性期再灌注治疗及二级预防抗血小板治疗等领域取得了多项进展。本指南就缺血性卒中急性期评估及诊断、再灌注治疗、抗血小板治疗、其他治疗、常规支持治疗及并发症管理、病因及发病机制的早期评估和诊断、针对病因和发病机制的干预、危险因素管理及长期干预更新推荐意见。 Abstract: The incidence of stroke in the Chinese population is still on the rise, accounting for nearly one-fourth of the global annual stroke cases. Among adults aged 40 or above in China, ischaemic stroke (IS) accounted for approximately 86.8% of all strokes. Since the publication of the 2019 Chinese Stroke Association guidelines, notable advancements have emerged in acute-phase reperfusion therapy and antiplatelet treatments for secondary prevention in IS. The guidelines have provided updated recommendations on evaluation and diagnosis of acute phase of ischaemic stroke, reperfusion therapy, antiplatelet therapy, other treatments in the acute phase, general supportive treatment and complications management, early evaluation and diagnosis of aetiology and pathogenesis, interventions targeting aetiology and pathogenesis, risk factors management, and long-term intervention

六盘山香水河小流域典型坡面的土壤电阻率空间变异/SPATIAL VARIATION OF SOIL ELECTRIC RESISTIVITY OF A TYPICAL SLOPE IN THE XIANGSHUIHE WATERSHED OF LIUPAN MOUNTAINS,NORTHWEST CHINA[J]

为了解坡面土壤水文特征的空间分布,采用多电极电阻仪法(ERT),于2009年5月初在宁夏六盘山香水河小流域一个长约600 m的华北落叶松人工林典型坡面上,设置了从坡顶至坡底的1条纵向样线及处于不同坡位的水平分布的3条横向样线,多点测定了多层土壤的电阻率值并分析其空间变异特征.结果表明,土壤电阻率在纵向样线上总体有较好的空间连续性及一定的空间变异性,随着坡位下降,电阻率呈现出由坡上至坡中上逐渐减小和然后又恢复性增大的过程.由于局部特殊的土壤特征、地貌及植被分布差异,使土壤电阻率沿坡面纵向变异程度大于不同坡位的横向变异程度.在土层垂直方向上,由于石砾含量和岩石比例随深度逐渐增多,电阻率表现为随深度增加逐渐增大.电阻率与土壤总孔隙度和体积含水率相关最紧密,尤其与体积含水率相关较好,说明通过测定坡面电阻率推求土壤水分等土壤特性的坡面变化是可行的