摘要：Solution-based routes have been widely applied in the synthesis of *** is desirable to choose or design precursors,ligands,and solvent molecules at the molecular level to allow the synthesis of lowdimensional nanocrystals with various shapes and *** increasing requirements for the integration of the properties of nanocrystals have produced a high demand for the rational design and fine control of complex structures,in terms of both the composition and the *** meet this demand,researchers have developed new synthetic strategies to produce more complex and more functional *** procedures involve systematic engineering,which focuses on the whole synthetic procedure,instead of just the molecular *** review focuses mainly on the work of yadong Li’s group over the last decade.

摘要：住院医师规范化培训是培养医学专业人才的必经途径。通过优化培训方案，建立以专业为导向、提升综合素质为目标的训练与评价体系，培养基础理论全面、临床技能扎实，具有独立临床思维、实践能力及科研创新意识的高素质住院医师；成为感染病专业学科发展与人才建设所面临的重要问题。结合我单位在感染病学科住院医师规范化培训方面的经验，提出建立“以学科为基地”，基于“优化设计、创新培养、素质评价”一体化的住院医师规范化培训模式。

摘要：目的临床实践能力与医学道德素养是衡量教育成功不可或缺的两大要素,本研究旨在探讨在突发公共卫生事件背景下临床专业学位研究生在感染病学科教学中的教育改革实施效果。方法选取2017年1月至2023年6月河北医科大学内科学专业博士、硕士研究生100名作为研究对象,其中针对2020年1月至2023年6月突发公共卫生事件以来学校在读感染病学、非感染病学临床专业学位50名博士、硕士研究生开展创新型模式教学,并以2017年1月至2019年12月毕业的50名博士、硕士研究生作为对照。采用调查问卷横断面分析对比教学改革实践的成效及不足。结果对所有纳入本研究的专业学位研究生共发放100份问卷,回收有效问卷99份。问卷第一部分,教学改革组研究生认为创新型教学模式在知识掌握、临床能力提升、疑难病例诊治能力、自主解决问题能力、与人沟通合作能力等方面总体“有帮助”和“很有帮助”人数高于传统教学组,创新型教学改革优于传统教学模式,差异有统计学意义(P<0.05);在对教学改革实施满意度调查中,教学改革组总体满意度高于传统教学组(100%vs.63.27%),差异有统计学意义(P<0.001);问卷第二部分,教学改革组在思政教育的必要性、深度与广度上的满意度高于传统教学组,差异有统计学意义(P<0.05);问卷第三部分,教学改革组在提升学生学习效率、自主学习能力、科研设计水平、创新理念培养4个方面有帮助和很有帮助人数高于传统教学组,差异有统计学意义(P<0.05)。结论现代医学教育应培养德才兼备的创新型拔尖人才,将基于临床教学实践创新、自主学习能力培养与当前公共卫生事件背景下的思政教育融合对于提高教学质量、培养医学人才具有重要的社会意义和实践价值。

摘要：铝硅合金拥有良好的成型性和较高的力学性能,被广泛应用于各个行业。但过共晶铝硅合金铸态组织中存在的粗大不规则块状初晶硅相会割裂基体,显著降低合金力学性能。本文采用OM、SEM及万能材料试验机等研究混合稀土La、Ce变质A390过共晶铝硅合金的微观组织和力学性能。结果表明,混合稀土对初晶硅的变质效果明显,随着混合稀土含量的增加,初晶硅的体积分数和合金的力学性能呈先增加后降低的趋势,当混合稀土加入量为0.58%(其中La为0.33%,Ce为0.25%,质量分数)时,初晶硅的体积分数达到最小值9.37%,铸态合金的抗拉强度和伸长率分别为229 MPa和1.7%。

摘要：通过习题课,可以使学生深化对物理知识的理解,领会物理学中特有的思维方式和基本方法论,培养分析问题,解决问题的能力.一堂好的物理习题课,需要用系统的科学方法去引导和训练学生.

摘要：基于任意拉格朗日-欧拉(Arbitrary Lagrangian-Eulerian,ALE)方法,对海底电缆在位情况下土壤覆盖物射流清理过程进行探讨,并分析射流速度和海床强度在海底电缆土壤覆盖物清理过程中对海底电缆受力损伤的影响。结果表明:当海床土壤相同时,射流速度越大,海底电缆受力越大,当射流速度为50 m/s时海底电缆将发生破坏;在相同射流速度下,海床土体的剪切模量、内聚力和摩擦角越小,海底电缆受力越大。在海底电缆覆盖物清理过程中需要根据海床强度选择相对应的射流速度,以满足清理要求。研究成果可为海底电缆土壤覆盖物清理技术研究提供参考依据。

摘要：为解决测井过程中声波变密度仪器偏心导致的声波幅度降低及固井质量评价不准确等问题,分析了声波变密度测井偏心影响及产生原理;在声波变密度测井数值模拟的基础上提出了均匀介质条件下声波变密度测井偏心影响的校正模型,设计了声波幅度偏心校正模型的验证装置,其室内实测数据证明了偏心校正模型的可靠性;从偏心距大小和准确获取首波数据两方面分析了该校正模型的适应性。偏心校正模型在长庆油田余X井的现场应用表明,利用偏心校正模型校正后的声波幅度与扶正条件下的声波幅度基本一致,证明该模型能有效校正仪器偏心引起的声波幅度偏差。研究结果表明偏心校正模型在偏心距小于9.37 mm时,可为声波变密度测井数据的校正提供技术支持。

摘要：Nowadays, carbon fiber composite material is becoming more and more popular in aero engine industry due to its high specific strength and stiffness. Laminate carbon fiber composite material is widely used to manufacture the high load wide chord fan blade, containment casing, etc. The aeroelastic behavior of composite product is critical for the optimization of the product design and manufacturing. In order to explore its aeroelastic property, this paper discusses the coupled simulation of aerodynamic excitation applied on laminate composite material plate. Mechanical behavior of composite material plate is different from that of isotropic material plate such as metal plate, because it is anisotropy and has relative high mechanical damping due to resin between plies. These plates to be studied are designed using 4 different layup configurations which follow the design methods for composite fan blade. The numerical simulation of force response analysis mainly uses single frequency mechanical force input to simulate the electromagnetic shakers or other actuators, which could transmit mechanical force to the test parts. Meanwhile, pulsed air excitation is another way to "shake" the test parts. This excitation method induces aero damping into the test part and simulates the unsteady flow in aero engine, which could cause aeroelastic problems, such as flutter, forced response and non-synchronous vibration(NSV). In this study, numerical simulation using coupled method is conducted to explore the characteristics of laminate composite plates and the property of aerodynamic excitation force generated by pulsed air jet device. Modal analysis of composite plate shows that different ply stacking sequences have a significant impact on the plate vibration characteristics. Air pulse frequency and amplitude in flow field analysis are calibrated by hot wire anemometer results. As the air pulse frequency and amplitude are varied, incident angle of flow and layup configurations of plat

摘要：A flow mathematical model with multiple horizontal wells considering interference between wells and fractures was established by taking the variable width conductivity fractures as basic flow *** a semi-analytical approach was proposed to model the production performance of full-life cycle in well pad and to investigate the effect of fracture length,flow capacity,well spacing and fracture spacing on estimated ultimate recovery(EUR).Finally,an integrated workflow is developed to optimize drilling and completion parameters of the horizontal wells by incorporating the productivity prediction and economic *** is defined as nested optimization which consists of outer-optimization shell(i.e.,economic profit as outer constraint)and inner-optimization shell(i.e.,fracturing scale as inner constraint).The results show that,when the constraint conditions aren’t considered,the performance of the well pad can be improved by increasing contact area between fracture and formation,reducing interference between fractures/wells,balancing inflow and outflow between fracture and formation,but there is no best compromise between drilling and completion *** only the inner constraint condition is considered,there only exists the optimal fracture conductivity and fracture *** considering both inner and outer constraints,the optimization decisions including fracture conductivity and fracture length,well spacing,fracture spacing are achieved and *** the fracturing scale is small,small well spacing,wide fracture spacing and short fracture should be *** the fracturing scale is large,big well spacing,small fracture spacing and long fracture should be used.

摘要：目的:调查兰州市青少年屈光状况,分析青少年近视发病的趋势及诱发近视的因素,为有效预防近视提供依据。方法:采用横断面调查设计,抽取兰州市2354名中小学生进行问卷调查,并对其进行眼科检查,如选用室内灯箱式E字标准对数视力表检查双眼视力,使用Topcon公司的电脑验光仪进行验光及裂隙灯检查等。结果:兰州市近视患病率为67.9%,男生近视比例为69.3%,女生近视比例为66.3%,城市学生近视比例70.1%,农村学生近视比例61.4%,学生年级越高,近视程度越严重。近视的影响因素也随生活习惯的改变而改变,身高、体重、每天课余学习时间增加、假期中每天玩电脑时间的增加及每天睡眠时间的减少可致近视患病率增加,每日户外活动时间增加可减少近视的患病率。结论:兰州市青少年的近视患病率高发,应引起学校和家长的高度重视,及早采取必要措施进行积极预防,培养学生健康的用眼习惯,提高学生保护视力的意识。