检索结果-南通市图书馆

维普期刊数据库博看期刊

Droplet Undercooling During Containerless Processing in a Drop Tube

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2004年第6期21卷 1120-1123页

作者： wangnan WEIBing-Bo DepartmentofAppliedPhysics NorthwesternPolytechnicalUniversityXian710072

The droplet undercooling prior to crystallization during containerless processing in a drop tube is calculated on the basis of nucleation theory and processing parameters. The influences of droplet size, wetting angle, and cooling rate on undercooling are also evaluated under the situation of heterogeneous nucleation. An experimental study of containerless solidification is performed on Ag28.1Cu41.4Ge30.5 ternary alloy in comparison with the theoretical analysis. It is revealed that, in the case of heterogeneous catalysis, the droplet size is only an ostensible parameter to influence undercooling, whereas the wetting angle is the essentially dominating factor. The different cooling rates in such a case also have an effect on droplet undercooling, but this effect is not significant. The calculated results will agree well with the experimental data if the inverse relationship between wetting angle and droplet size is given.

关键词： Wetting

Hard X-ray diffraction enhanced imaging only using two crystals

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2004年第20期49卷 2120-2125页

作者： LIGang wangnan WUZiyu BeijingSynchrotronRadiationFacility.InstituteofHighEnergyPhysics.ChineseAcademyofSciences.Beijing100039.China CollegeofMachine-electronics.BeijingIndustryUniversity.Beijing100022.China

Different configurations for the monochroma-tor crystals and the analyzer crystals have been used in hard X-ray diffraction enhanced imaging (DEI) methods to over-come the complex task to adjust each of them to the ideal position. Here we present a very compact DEI configuration, and preliminary results of experiments performed at the Beijing Synchrotron Radiation Facility (BSRF) using only two crystals: the first one acting as monochromator and the second one as analyzer in the Bragg geometry. Refraction contrast images characterized by high contrast and spatial resolution are obtained and compared with absorption im-ages. Differences among these images will be outlined and discussed emphasizing the potential capabilities of this very simple layout that guarantees a high transmission efficiency.

关键词：强X-射线衍射图像增强晶体分析摇摆曲线同步加速器辐射晶体单色器

低分子肝素治疗妊娠期糖尿病伴孕中期血脂异常孕妇的临床效果

在线全文

学校读者我要写书评

暂无评论

临床医学工程 2024年第8期31卷 931-932页

作者：车盼盼闫望南开封市妇幼保健院产一科河南开封475000 开封市妇幼保健院妇科河南开封475000

目的探讨低分子肝素治疗妊娠期糖尿病(GDM)伴孕中期血脂异常孕妇的临床效果。方法选取2020年10月至2022年12月在我院产检并分娩的80例GDM伴孕中期血脂异常孕妇,随机分为两组各40例。对照组给予常规治疗,研究组在对照组基础上给予低分子... 详细信息

目的探讨低分子肝素治疗妊娠期糖尿病(GDM)伴孕中期血脂异常孕妇的临床效果。方法选取2020年10月至2022年12月在我院产检并分娩的80例GDM伴孕中期血脂异常孕妇,随机分为两组各40例。对照组给予常规治疗,研究组在对照组基础上给予低分子肝素治疗。比较两组的血脂水平、母婴结局。结果治疗后,两组的HDL水平均显著高于治疗前,LDL、TG、TC水平均显著低于治疗前(P<0.05);且研究组的HDL水平显著高于对照组,LDL、TG、TC水平均显著低于对照组(P<0.05)。研究组的不良母婴结局总发生率为7.50%,显著低于对照组的25.00%(P<0.05)。结论低分子肝素治疗GDM伴孕中期血脂异常孕妇的效果显著,能够明显改善血脂水平,减少不良母婴结局发生风险。

关键词：妊娠期糖尿病血脂异常低分子肝素血脂母婴结局

Rapid solidification mecha-nism of Ag_(60)Sb_(34)Cu_(6) ternaryalloy in drop tube

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2004年第17期49卷 1801-1805页

作者： RUANYing wangnan CAOChongde WEIBingbo LaboratoryofMaterialsScienceinSpace DepartmentofAppliedPhysicsNorthwesternPolytechnicalUniversityXi'an710072China

Droplets of Ag60Sb34Cu6 ternary alloy within the diameter range of 60—800 μm were rapidly solidified by means of drop tube containerless processing, and the solidi- fication mechanism is analyzed. With a decrease in droplet size, the cooling rate increases from 57 to 5.8×104 K/s. The maximum undercooling is determined to be 180 K (0.23TL) and the microstructure of primary ε(Ag3Sb) dendrite refines drastically until homogenous equiaxed dendrite forms. Ex- perimental results indicate that (ε+Ag) pseudobinary eutectic cannot form under high undercooling conditions and the solubility of Ag in primary ε phase increases as undercooling increases. Based on thermal analysis and crystal growth morphology, it is found that this alloy is solidified in two ways corresponding to different undercooling levels.

关键词：快速凝固机理 Ag60Sb34Cu6 三重合金高冷却现象晶核银锑铜合金

在线全文

学校读者我要写书评

暂无评论

CPT在实现我国控烟目标中的应用探索

北京大学学报（医学版） 2024年第3期56卷 479-486页

作者：杨晓尘曹望楠林昊翔张蓝超林雨欣陈子砚常春北京大学公共卫生学院社会医学与健康教育系北京100191 北京大学全球健康发展研究院北京100871

目的:采用卷烟购买任务(cigarette purchase task,CPT)对我国吸烟者的卷烟需求进行评价,并评估不同假设情境下的卷烟价格,以实现“健康中国2030”行动中降低吸烟率的目标。方法:共计447名受试者通过问卷调查完成CPT,根据价格框架和对应... 详细信息

目的:采用卷烟购买任务(cigarette purchase task,CPT)对我国吸烟者的卷烟需求进行评价,并评估不同假设情境下的卷烟价格,以实现“健康中国2030”行动中降低吸烟率的目标。方法:共计447名受试者通过问卷调查完成CPT,根据价格框架和对应的卷烟消费量拟合卷烟需求曲线,并得到5个相关指标,分别为强度(免费时的卷烟消费量)、断点(消费量降为0的价格)、最高消费额(maximum output,Omax)、最高价格(maximum price,Pmax,最高消费额对应的卷烟价格)和弹性(消费量变化与价格变化的比率)。采用单因素分析探索CPT指标和社会人口学特征、吸烟特征的相关性。采用单相衰减模型拟合戒烟率-卷烟价格曲线,并确定一系列情境下能使吸烟率降到20%的最佳卷烟价格。结果:从卷烟需求曲线得到吸烟者弹性为0.54,表明价格上涨10%可使吸烟率降低5.4%。收入越高的吸烟者对卷烟价格敏感性越低(弹性=-2.31,P=0.028)。CPT指标在常用卷烟价格、吸烟量和烟草依赖程度不同的吸烟者中差异有统计学意义,常用卷烟价格越高的吸烟者断点、最高消费额和最高价格均越高,弹性越低(P=0.001),烟草依赖程度越高的吸烟者强度、断点、最高消费额和最高价格均越高,而弹性越低(P=0.001),吸烟量更大的吸烟者强度、最高消费额更高,弹性更低(P<0.001)。要实现将吸烟率降至20%的目标,卷烟的价格至少为37.36元/包,调整受教育水平和收入水平后,卷烟价格分别至少为37.37元/包和37.84元/包。结论:CPT指标与收入水平和常用卷烟价格、吸烟量和烟草依赖程度显著相关,在研究影响吸烟行为的价格因素方面有应用空间;本研究模型拟合卷烟价格远超当前实际市场水平,应采取更有力的政策措施提高烟草税和卷烟零售价,以实现将吸烟率降低到20%的“健康中国2030”目标。

关键词：卷烟需求卷烟购买任务烟草控制烟草税

维普期刊数据库博看期刊

Neutron Stars in the Model of Non—linear Realization of SU（2） Chiral Symmetry Spontaneous Breaking

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2003年第5期39卷 603-606页

作者： wangnan SUNBao-Xi LUEXiao-Fu ZHAOEn-Guang InstituteofTeorticalphysics theChineseAcademyofSciencesBeijing100080China InstituteofHighEnergyPhysics theChineseAcademyofSciencesP.O.Box918(4)Beijing100039China InstituteofTeorticalphysics theChineseAcademyofSciencesBeijing100080China DepartmentofPhysics SichuanuniversityChengdu610064China InstituteofTeorticalphysics theChineseAcademyofSciencesBeijing100080China CenterofTheoreticalNuclearPhysics NationalLaboratoryofHeavyIonAcceleratorLanzhou730000CHina DepartmentofPhysics TsinghuaUniversityBeijing1

The properties of neutron stars are studied in a relativistic mean-field model with SU(2) chiral symmetry spontaneous breaking being considered. The calculation results indicate that the effects of the chiral symmetry... 详细信息

关键词： neutron star chiral symmetry spontaneous breaking relativistic mean-field approximation

HIV暴露前预防认知量表的编制及在男男性行为者中的初步验证

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中国艾滋病性病 2024年第5期30卷 487-492页

作者：林浩郭鹏玥常春王晓冬张博曹望楠李菁华北京大学公共卫生学院北京100191 中山大学公共卫生学院广州510080 成都同乐健康咨询服务中心成都610021

目的编制并验证基于健康行动过程取向理论的PrEP认知量表,为进一步探讨PrEP的认知影响因素和推广机制提供工具。方法以量表的六个主要理论要素(自我效能、积极结果预期、消极结果预期、风险感知、使用意愿和行动计划)构建量表条目池,于2... 详细信息

目的编制并验证基于健康行动过程取向理论的PrEP认知量表,为进一步探讨PrEP的认知影响因素和推广机制提供工具。方法以量表的六个主要理论要素(自我效能、积极结果预期、消极结果预期、风险感知、使用意愿和行动计划)构建量表条目池,于2023年10月26日至11月27日在成都和合肥两市的MSM中进行预调查,调查内容包括一般人口学特征、HIV暴露风险、PrEP使用情况以及PrEP认知量表,评估量表的内容效度、表面效度和区分效度,以Cronbach’sα系数评价量表信度,并在一部分调查对象中检测量表的重测信度。结果在参与预调查的32名研究对象中,53.1%(17人)存在HIV暴露风险,34.4%(11人)曾经或正在使用PrEP,在服药方案的选择偏好上,研究对象首选按需服药方案,长效注射方案次之,最后为每日服药方案。由HIV领域专家、同伴领袖和一般适用人群对量表的内容效度和表面效度进行定性评价,修改各条目的措辞和顺序,最终形成9维度44条目PrEP认知量表。总Cronbach’sα为0.882,重测信度组内相关系数为0.895。结论量表的信效度良好,可用于测量PrEP适用人群的PrEP认知水平,为PrEP推广提供评估工具和参考。

关键词：艾滋病病毒暴露前预防健康行动过程取向理论信度效度

Manipulating hot carrier cooling in silicon phononic crystals opens new application opportunities

在线全文

学校读者我要写书评

暂无评论

中国化学快报:英文版 2023年第9期34卷 1-2页

作者： Peng Zhou Shaojuan Lu wangnan Li Shulai Lei State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices Hubei University of Arts and ScienceXiangyang 441053China Hubei Institute of Aerospace Chemotechnology Xiangyang 441003China Hubei Longzhong Laboratory Xiangyang 441000China

Phononic crystals(PnCs)have had a multiple of important and promising applications such as sonic diodes,acoustic cloaking,optomechanic,and thermoelectrics[1–5].Undoubtably,it is of significance to explore new finding... 详细信息

关键词： diodes application finding

Influence of Nuclear Deformation on the Potential Energy Surface in Di—Nuclear Model

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2003年第5期20卷 635-638页

作者： wangnan ZHAOEn-Guang LIJian-Feng LIWen-Fei XUHu-Shan ZUOWei LIJun-Qing InstituteofTheoreticalPhysics ChineseAcademyofSciencesBeijing100080 InstituteofModermPhysics ChineseAcademyofSciencesLanzhou730000

Influence of the nuclear deformation on the potential energy surface (PES) in a di-nuclear system is studied in details. It is found that the PES shape changes greatly due to the deformation effect. The top point of the PES could be reduced significantly, which implies that the optimum excitation energy could also be reduced greatly and may enhance the formation probability of the compound nucleus. The dynamical deformation as a function of the reaction time in the reaction process is dramatic. The Z/N ratios of fragments tend to follow that of the compound nucleus during the nucleon exchange process, but to fluctuate.

关键词：原子核物理学变形 PES 核反应二次核模型能量