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基于膨胀实验数据获取角膜屈光手术后力学参数的方法初探 被引量:2
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作者 张迪 muhammad A.khan +4 位作者 秦晓 张海霞 李林 林丁 刘志成 《中国医学物理学杂志》 CSCD 2018年第4期449-454,共6页
目的:基于离体膨胀实验获得的角膜顶点与压力数据,探索利用有限元方法获得屈光手术后角膜力学参数的方法。方法:取实验兔4只,左眼为手术眼,右眼为对照眼。行标准的LASIK术实验兔2只,仅制瓣未对角膜基质层消融的实验兔2只,分别于术后不... 目的:基于离体膨胀实验获得的角膜顶点与压力数据,探索利用有限元方法获得屈光手术后角膜力学参数的方法。方法:取实验兔4只,左眼为手术眼,右眼为对照眼。行标准的LASIK术实验兔2只,仅制瓣未对角膜基质层消融的实验兔2只,分别于术后不同时间点实施离体角膜膨胀实验。在离体膨胀实验中,利用位移传感器、压力传感器和显微镜分别获得角膜顶点位移、角膜内压力及角膜正侧面轮廓图像。根据获得的角膜轮廓图像构建角膜几何模型,用二阶Ogden模型描述角膜的本构关系,通过有限元方法模拟膨胀实验,将计算结果与膨胀实验数据比对确定角膜的力学参数,分析屈光手术后饲养一定时间时角膜的力学特性。结果:角膜膨胀实验获得的角膜顶点位移与压力呈非线性关系。在相同压力下,术后饲养一定时间后的兔眼角膜顶点位移量比对照眼小。二阶Ogden模型可以较好地描述屈光手术后角膜的力学特性。屈光手术后角膜弹性模量较对照眼大。结论:基于整体膨胀实验数据,利用有限元方法模拟角膜膨胀实验反推屈光手术后角膜力学参数的方法是可行的。 展开更多
关键词 准分子激光原位角膜磨镶术 角膜 膨胀实验 力学参数 二阶Ogden模型 有限元方法
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COSMO-RS: An ionic liquid prescreening tool for gas hydrate mitigation
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作者 Cornelius B.Bavoh Bhajan Lal +3 位作者 Omar Nashed muhammad S.khan Lau K.Keong Mohd.Azmi Bustam 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第11期1619-1624,共6页
Recently ionic liquids(ILs) are introduced as novel dual function gas hydrate inhibitors. However, no desired gas hydrate inhibition has been reported due to poor IL selection and/or tuning method. Trial & error a... Recently ionic liquids(ILs) are introduced as novel dual function gas hydrate inhibitors. However, no desired gas hydrate inhibition has been reported due to poor IL selection and/or tuning method. Trial & error as well as selection based on existing literature are the methods currently employed for selecting and/or tuning ILs. These methods are probabilistic, time consuming, expensive and may not result in selecting high performance ILs for gas hydrate mitigation. In this work, COSMO-RS is considered as a prescreening tool of ILs for gas hydrate mitigation by predicting the hydrogen bonding energies(E_(HB)) of studied IL inhibitors and comparing the predicted E_(HB) to the depression temperature(?) and induction time. Results show that, predicted EHBand chain length of ILs strongly relate and significantly affect the gas hydrate inhibition depression temperature but correlate moderately(R = 0.70) with average induction time in literature. It is deduced from the results that, ? increases with increasing IL EHBand/or decreases with increasing chain length. However, the cation–anion pairing of ILs also affects IL gas hydrate inhibition performance. Furthermore, a visual and better understanding of IL/water behavior for gas hydrate inhibition in terms of hydrogen bond donor and acceptor interaction analysis is also presented by determining the sigma profile and sigma potential of studied IL cations and anions used for gas hydrate mitigation for easy IL selection. 展开更多
关键词 Gas hydrates COSMO-RS Hydrogen bonding energies Ionic liquids Tuning
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巴基斯坦北部小喜马拉雅区Abbottabad组Sirban段寒武纪小壳化石的首次发现及其地层学意义 被引量:4
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作者 Shehryar Ahmed 潘兵 +5 位作者 Malik muhammad Saud Sajid khan 李国祥 muhammad Qasim 罗翠 孙晓娟 朱茂炎 《地层学杂志》 CSCD 北大核心 2023年第3期339-352,共14页
小壳化石是寒武系纽芬兰统年代地层划分和全球对比的主要生物地层学依据。长期以来,喜马拉雅西侧的巴基斯坦北部寒武纪早期小壳化石的发现较为零星,导致该地区埃迪卡拉纪与寒武纪过渡期地层序列的划分缺乏统一认识,相关地层时代归属十... 小壳化石是寒武系纽芬兰统年代地层划分和全球对比的主要生物地层学依据。长期以来,喜马拉雅西侧的巴基斯坦北部寒武纪早期小壳化石的发现较为零星,导致该地区埃迪卡拉纪与寒武纪过渡期地层序列的划分缺乏统一认识,相关地层时代归属十分不清晰。在第二次青藏科考任务的支持下,作者对巴基斯坦北部隶属于小喜马拉雅区的Hazara盆地东部前寒武纪与寒武纪过渡期地层Hazara组、Kakul组、Abbottabad组和Hazira组开展详细研究,首次在Kalu-di-Bandi剖面Abbottabad组Sirban段顶部硅磷质白云岩中发现了寒武纪纽芬兰世幸运期小壳化石组合。该小壳化石组合属种相对丰富,含有Anabarites trisulcatus、Protohertzina anabarica、Conotheca subcurvata、Hexangulaconularia formosa、Olivooides multisulcatus、Maikhanella pristinis、Lopochites latazonalis、Siphogonuchites sp.及Spirellus columnaris等分子。上述属种组合面貌常见于华南、印度北部、克什米尔、伊朗、蒙古国及西伯利亚的寒武纪纽芬兰世幸运期地层中,其中A.trisulcatus和P.anabarica是这一化石组合带中的标准分子。因此,本文以A.trisulcatus和P.anabarica的共同出现为标志,将Sirban段顶部的小壳化石组合命名为Anabarites trisulcatusProtohertzina anabarica组合带,时代上归属为寒武纪纽芬兰世幸运期。该化石组合的发现表明,该地区存在寒武纪幸运期地层记录,寒武系底界应位于Abbottabad组Sirban段内某个层位(不过确切的界线位置仍需将来进一步的生物地层学和化学地层学工作进行校对),同时也修正了前人将该地区寒武系底界置于Hazira组与Abbottabad组界线处或Abbottabad组与Kakul组界线处的观点。对比研究发现,Sirban段中的化石组合分子与华南A.trisulcatus-P.anabarica组合带面貌非常相似,且共有一些特征属种,支持寒武纪纽芬兰世印度次大陆北部的喜马拉雅区与华南之间的生物群存在� 展开更多
关键词 小壳化石 生物地层 Abbottabad组 纽芬兰统 巴基斯坦 小喜马拉雅区
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青藏高原及其周边寒武纪综合地层、生物群与古地理演化 被引量:1
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作者 孙智新 孙郎 +8 位作者 赵方臣 潘兵 Malik muhammad Saud Sajid khan Shehryar AHMED 杨传 苗兰云 殷宗军 李国祥 朱茂炎 《中国科学:地球科学》 CSCD 北大核心 2024年第4期968-991,共24页
青藏高原及其周边地区具有漫长且复杂的构造演化历史.印度北部、拉萨、羌塘、柴达木、中祁连等大小不同的克拉通和地块,以及位于它们之间的造山带构成了青藏高原的主体.寒武纪时期,这些克拉通和地块大多位于冈瓦纳大陆的西北缘,并以发... 青藏高原及其周边地区具有漫长且复杂的构造演化历史.印度北部、拉萨、羌塘、柴达木、中祁连等大小不同的克拉通和地块,以及位于它们之间的造山带构成了青藏高原的主体.寒武纪时期,这些克拉通和地块大多位于冈瓦纳大陆的西北缘,并以发育与原特提斯洋有关的复杂岩浆-构造运动而与周边的阿拉伯、中伊朗、阿富汗、塔里木、阿拉善、华北、华南和滇缅马等构造单元相关联.从地层记录上看,这一时期区域内的大部分稳定陆块上发育了由陆源碎屑岩和碳酸盐岩组成的浅水陆棚沉积,其中包含面貌相近的典型浅水相三叶虫组合.而在原特提斯洋中的祁连构造带,寒武系则是一套在大洋扩张环境下形成的、以中基性火山岩和硅质岩为主的复杂地层序列,其中包含的碳酸盐岩含有斜坡相三叶虫组合.本文在广泛文献调研的基础上,结合第二次青藏高原综合科学考察中的野外观察及新获得的化石证据,对青藏高原及其周边地区不同构造单元上寒武纪地层发育的总体特征进行了概述.在此基础上,利用可获得的生物地层学和同位素年代学等资料,总结了不同构造单元上寒武纪地层的划分和年代地层对比,编制了岩石和生物地层的综合对比表.此外,从生物古地理的角度,简要讨论了寒武纪研究区内主要构造单元的古地理相关性,以及与原特提斯构造带演变有关的问题. 展开更多
关键词 青藏高原 寒武系 地层 古地理 生物群 冈瓦纳大陆 原特提斯洋
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青藏高原及其周边成冰纪-埃迪卡拉纪综合地层、生物群与古地理演化 被引量:1
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作者 孙郎 Malik muhammad Saud Sajid khan +13 位作者 杨传 孙智新 潘兵 Shehryar AHMED 苗兰云 孙玮辰 胡春林 孙晓娟 罗翠 陈波 殷宗军 赵方臣 李国祥 朱茂炎 《中国科学:地球科学》 CSCD 北大核心 2024年第4期936-967,共32页
青藏高原及其周边的块体,包括印度板块、拉萨地块、羌塘地块、塔里木板块、欧龙布鲁克地块、中祁连地块、阿拉善地块、华北板块、扬子板块、中伊朗地块和阿曼等,以及各块体之间造山带的复杂演化历史是地球科学研究的前沿和热点.成冰系... 青藏高原及其周边的块体,包括印度板块、拉萨地块、羌塘地块、塔里木板块、欧龙布鲁克地块、中祁连地块、阿拉善地块、华北板块、扬子板块、中伊朗地块和阿曼等,以及各块体之间造山带的复杂演化历史是地球科学研究的前沿和热点.成冰系和埃迪卡拉系广泛分布于该地区的各个构造单元,其中阿曼、印度板块、扬子板块以及塔里木板块发育有相对完整的成冰系和埃迪卡拉系;而在中伊朗地块、南羌塘地块、中祁连地块、阿拉善地块及华北板块,目前已知仅有埃迪卡拉系发育.基于前人对青藏高原及其周边地区成冰系和埃迪卡拉系的研究,结合第二次青藏高原综合科学考察研究项目开展以来获得的新资料和研究进展,本文建立了该地区成冰系和埃迪卡拉系代表性地层序列对比表.在此基础上,本文梳理了该地区这一时期生物群和重大地质事件的研究现状和存在的问题.结果表明,该地区各板块埃迪卡拉纪化石的保存和组合面貌各具特色,但普遍发现有典型埃迪卡拉纪末期化石分子Cloudina和Shaanxilithes;除成冰纪两次全球性冰期事件外,在青藏高原北缘各块体(华北板块、阿拉善地块、北祁连构造带、中祁连地块、欧龙布鲁克地块、塔里木板块)以及伊朗中南部普遍记录了一次埃迪卡拉纪晚期的冰川事件,但该事件的时限、分布范围和成因有待进一步揭示;同时,埃迪卡拉纪中期DOUNCE/Shruam碳同位素负异常事件在青藏高原周边地区也具有广泛记录.综合现有研究资料发现,在成冰纪-埃迪卡拉纪期间,青藏高原及其周边地区大多数块体从罗迪尼亚超大陆裂解出来后,可能通过泛非运动构成东冈瓦纳大陆的一部分,而部分板块(如华北板块)位于冈瓦纳大陆和劳伦大陆之间.总体而言,该地区的主要块体在成冰纪-埃迪卡拉纪期间具体的古地理演化模型存在较多争议,亟需� 展开更多
关键词 青藏高原 成冰系 埃迪卡拉系 地层 古地理 生物群 冈瓦纳大陆
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Cryptanalysis of an identity-based public auditing protocol for cloud storage 被引量:4
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作者 Li-bing WU Jing WANG +1 位作者 De-biao HE muhammad-Khurram khan 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2017年第12期1972-1977,共6页
Public verification of data integrity is crucial for promoting the serviceability of cloud storage systems. Recently, Tan and Jia (2014) proposed an identity-based public verification (NaEPASC) protocol for cloud ... Public verification of data integrity is crucial for promoting the serviceability of cloud storage systems. Recently, Tan and Jia (2014) proposed an identity-based public verification (NaEPASC) protocol for cloud data to simplify key management and alleviate the burden of check tasks. They claimed that NaEPASC enables a third- party auditor (TPA) to verify the integrity of outsourced data with high efficiency and security in a cloud computing environment. However, in this paper, we pinpoint that NaEPASC is vulnerable to the signature forgery attack in the setup phase; i.e., a malicious cloud server can forge a valid signature for an arbitrary data block by using two correct signatures. Moreover, we demonstrate that NaEPASC is subject to data privacy threats in the challenge phase; i.e., an external attacker acting as a TPA can reveal the content of outsourced data. The analysis shows that NaEPASC is not secure in the data verification process. Therefore, our work is helpful for cryptographers and engineers to design and implement more secure and efficient identitv-based nublic alldit^n~ .~cheme~ far clnne] ~tnr^q~ 展开更多
关键词 Cloud data Public auditing Data integrity Data privacy
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Band Structure Characteristics of Two-Dimensional Si-A (Ge, Pb, Sn) Alloy-Air Holes Thermal Crystals
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作者 AZKA Umar 姜淳 KHUSHIK muhammad Hanif Ahmed khan 《Journal of Shanghai Jiaotong university(Science)》 EI 2023年第2期180-185,共6页
This paper designs the thermal crystals composed of alloy materials with air holes and analyzes their properties of band structures,heat transmission,and flux spectra.Thermal crystals composed of Si-A(A=Ge,Sn,Pb)alloy... This paper designs the thermal crystals composed of alloy materials with air holes and analyzes their properties of band structures,heat transmission,and flux spectra.Thermal crystals composed of Si-A(A=Ge,Sn,Pb)alloys as background materials and air holes with square array are used to construct an elastic-constant periodic structure and their high-frequency phononic band is calculated by deploying finite element methods.Moreover,this paper investigates heat transmission through a finite array of thermally excited phonons and presents the thermal crystal with maximum heat transport.The results show that a wider bandgap could be achieved by increasing the air hole radius and decreasing the lattice constant.In the alloy materials,with increasing atomic radius and thus atomic mass(Ge,Sn,Pb),the frequency range(contributed to thermal conductivity)shifts towards lower frequency.Hence,the bandgap frequencies also shift toward low frequency,but this decreasing rate is not constant or in order,so former may have a faster or slower decreasing rate than the later.Thus,the frequency range for the contribution of heat transportation overlaps with the bandgap frequency range.The development of thermal crystals is promising for managing heat and controlling the propagation of the thermal wave. 展开更多
关键词 thermal crystals PHONONS finite element method band structure periodic structure lattice constant
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Dependency of Torque on Aerofoilcamber Variation in Vertical Axis Wind Turbine
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作者 Adil Loya muhammad Zia Ullah khan +1 位作者 Rumeel Ahmad Bhutta muhammad Saeed 《World Journal of Mechanics》 2016年第11期472-486,共15页
The advancements in the wind turbine technology specially associated with Vertical Axis Wind Turbines (VAWT), has been improved for last couple of years. This is due to extensive use of computational techniques. This ... The advancements in the wind turbine technology specially associated with Vertical Axis Wind Turbines (VAWT), has been improved for last couple of years. This is due to extensive use of computational techniques. This paper investigates dependency of torque on aerofoil geometry by performing numerical simulation on Darrieustype VAWT with fix pitch blades. Coordinate points for aerofoil was generated using Java Foil software. Reynolds-Averaged Navier Stokes (RANS) turbulence modelling was used for predicting the flow and efficiency of the three blades VAWT. The unsteady flow condition was considered to make simulation as realistic as possible. In order to visualize high strain flow and separation, we used two equation models i.e. k-ε with RNG. NACA 0012 aerofoil was used and camber variations were carried out for developing samples of aerofoil to check the enhancement in performance of VAWT. Results demonstrate the torque and power along with its coefficients. It has been investigated that the performance efficiency was significantly improved by changing the aerofoil camber, demonstrating highest torque with camber (C3) aerofoil and the least performance was observed using camber (C0). 展开更多
关键词 Co-Efficient of Moment CFD TORQUE Power FLUENT Java Foil
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Study on the Physical and Mechanical Properties of Al-Powder Reinforced Bioactive Glass: Ceramic Composite Material
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作者 muhammad Hafizur Rahman khan Sazzad Hossain Mohammad Maksudur Rahman 《Advances in Materials Physics and Chemistry》 2022年第2期19-32,共14页
Glass-ceramic samples, having composition of SiO<sub>2</sub>-35, CaO-45, Na<sub>2</sub>O-10 and P<sub>2</sub>O<sub>5</sub>-10 in weight ratio were prepared through sinte... Glass-ceramic samples, having composition of SiO<sub>2</sub>-35, CaO-45, Na<sub>2</sub>O-10 and P<sub>2</sub>O<sub>5</sub>-10 in weight ratio were prepared through sintering route. Glass powder was reinforced by Al powder. The strength of glass-ceramic composite was found to be temperature dependent, and it varies with the addition of Al powder. Flexural strength increases with the increase of powder addition and sintering temperature, however, decreases with the increase of sintering time. There is an optimum temperature (>1100℃) above which flexural strength of all samples decreases. Bulk density changes to a higher value as the addition of Al-powder increases up to 3% by weight above which density decreases slowly. On the other hand, apparent porosity and water absorption decrease with the increase of percentage of Al powder added. Porosity and water absorption also showed a dependent characteristic on sintering time and sintering temperature. 展开更多
关键词 BIOMATERIALS Glass Ceramics Aluminum Powder Composite Material
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Gain Properties of Triply-Doped Graphene-Insulator-Graphene Nanosheet Waveguide
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作者 KHUSHIK muhammad Hanif Ahmed khan JIANG Chun 《Journal of Shanghai Jiaotong university(Science)》 EI 2019年第1期7-11,共5页
Er^(3+)-Tm^(3+)-Pr^(3+)triply-doped graphene-glass-graphene(GGG) nanosheet waveguide amplifier, which is a promising candidate for integrated photonic devices, is modelled and numerically analyzed. The designed wavegu... Er^(3+)-Tm^(3+)-Pr^(3+)triply-doped graphene-glass-graphene(GGG) nanosheet waveguide amplifier, which is a promising candidate for integrated photonic devices, is modelled and numerically analyzed. The designed waveguide is composed of a triply-doped tellurite glass core. The core is sandwiched between two graphene layers.The rate and power propagation equations of a heterogeneous multi-level laser medium are set up and solved numerically to study the effects of waveguide length and active ion concentrations on amplifier performance at five different input signal wavelengths(1.310, 1.470, 1.530, 1.600 and 1.650 μm). The analytical results show that rareearth ion dopant concentrations at an order of 10^(26) ion/m^3, waveguide length at 0.1 m and pump power at 100 m W can amplify 1.530 and 1.600 μm input signals with 1 μW power up to approximately 20.0 and 24.0 dB respectively.Finite-difference time-domain(FDTD) simulation results show that mode field radius of GGG waveguide is smaller than that of silicon waveguide. Consequently, GGG waveguide with the same pump and signal power and the same gain-medium length can produce higher gain than silicon waveguide. 展开更多
关键词 nanosheet waveguide Er^(3+)-Tm^(3+)-Pr^(3+) gain medium
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25年长期定位不同施肥措施对关中塿土水力学性质的影响 被引量:12
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作者 兰志龙 muhammad Numan khan +3 位作者 Tanveer Ali Sial 杨学云 赵英 张建国 《农业工程学报》 EI CAS CSCD 北大核心 2018年第24期100-106,共7页
土壤水力学性质和功能的变化是评价长期施肥是否维持土壤可持续健康发展的重要方面。该研究通过采取"国家黄土肥力与肥料效益监测基地"的表层原状土壤,分析测定了撂荒(LH)、休闲(XX)、不施肥(CK)、单施氮肥(N)、氮磷钾肥(NPK... 土壤水力学性质和功能的变化是评价长期施肥是否维持土壤可持续健康发展的重要方面。该研究通过采取"国家黄土肥力与肥料效益监测基地"的表层原状土壤,分析测定了撂荒(LH)、休闲(XX)、不施肥(CK)、单施氮肥(N)、氮磷钾肥(NPK)和有机肥与氮磷钾肥配施(MNPK)6个处理的土壤水分特征曲线、饱和导水率和紧实度等指标,评价了长期定位施肥对土壤基本物理性质和水力学性质的影响。结果表明:1)与CK、N和NPK处理相比,MNPK处理显著提高了土壤有机碳、饱和导水率和孔隙度,而降低了土壤容重和紧实度(P<0.05)。2)不同施肥处理之间的土壤水分特征曲线表现出一定的差异,其土壤持水能力强弱为:XX<N≈NPK<CK<MNPK<LH;MNPK处理较CK、N和NPK处理持水能力分别提高2.57%、3.33%和7.34%;V-G模型拟合结果表明残余含水量(θ_r)、饱和含水量(θ_s)和进气值倒数(a)都存在一定程度的差异,θ_r在MNPK处理最大,XX最小;θ_s在N处理最大,MNPK次之,CK最小。进气值(1/a)在XX处理最大,LH最小。3)当量孔隙的分布主要在>9μm大孔隙范围内,其次是<0.2μm小孔隙范围,0.2~9μm之间的中孔隙分布较少。综上,MNPK有助于改善土壤结构,提高土壤持水性,降低土壤容重和紧实度,有助于作物生长和高产,是关中地区较为适宜的施肥措施。 展开更多
关键词 土壤 水力学 水分特征曲线 饱和导水率 土壤紧实度 塿土
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北京地区中国荷斯坦牛体细胞评分差值变化规律及遗传力估计 被引量:9
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作者 史良玉 张瑞强 +8 位作者 李想 Serafino Musa Abdelkarim Augustino muhammad Zahoor khan 刘林 肖炜 唐韶青 张毅 王雅春 俞英 《畜牧兽医学报》 CAS CSCD 北大核心 2018年第5期935-941,共7页
旨在对北京地区中国荷斯坦牛体细胞评分(SCS)差值变化规律进行探索以及遗传力估计。本研究通过对相邻两个泌乳月SCS差值的计算,利用最小二乘法对北京地区1998-2016年间121个牛场中78 386头中国荷斯坦奶牛DHI数据进行分析,并利用DMU软件... 旨在对北京地区中国荷斯坦牛体细胞评分(SCS)差值变化规律进行探索以及遗传力估计。本研究通过对相邻两个泌乳月SCS差值的计算,利用最小二乘法对北京地区1998-2016年间121个牛场中78 386头中国荷斯坦奶牛DHI数据进行分析,并利用DMU软件和线性混合模型估计SCS差值各方差组分,计算其遗传力。结果表明,场规模、当前测定年、当前测定季节、胎次、产犊季节、当前泌乳月对SCS差值具有极显著性影响(P<0.01);SCS差值遗传力为(0.054±0.003)。其中,一胎、二胎、三胎SCS差值遗传力分别为(0.070±0.005)、(0.045±0.004)、(0.052±0.007)。结果表明,SCS差值作为一种实时简易检测隐性乳房炎发生的指标,其遗传力的估计在中国荷斯坦牛抗隐性乳房炎选择中具有重要作用。 展开更多
关键词 中国荷斯坦牛 隐性乳房炎 SCC SCS差值 遗传力估计
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“新医科”背景下泌尿外科双语教学模式在“5+3”一体化医学生规培中的应用 被引量:8
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作者 张连栋 李和程 +4 位作者 高明 张鹏 种铁 muhammad Sohail khan 王子明 《医学教育研究与实践》 2022年第1期16-20,共5页
目的研究“新医科”背景下泌尿外科双语教学模式在“5+3”一体化医学生规培轮转中的应用效果,探索提高专业英语水平的方法。方法选择于我院泌尿外科规培的“5+3”一体化医学生70人,随机分为对照组及观察组,分别有35人,对照组采用常规住... 目的研究“新医科”背景下泌尿外科双语教学模式在“5+3”一体化医学生规培轮转中的应用效果,探索提高专业英语水平的方法。方法选择于我院泌尿外科规培的“5+3”一体化医学生70人,随机分为对照组及观察组,分别有35人,对照组采用常规住院医师规范化培训带教模式,观察组采用双语教学模式并有留学生参与,规培1月后分别进行英文水平测试、教育环境量表评估并进行教学评价。结果干预后对照组英文翻译、病例分析较干预前未见显著性差异(P>0.05),干预后观察组英文翻译、病例分析较干预前显著升高(P<0.05),显著高于对照组干预后成绩(P<0.05)。比较两组DREEM评分,观察组对学习的知觉、对教师的知觉、对学术的知觉评分较对照组均有显著性升高(P<0.05)。观察组增加学习兴趣、拓宽国际化视野和学习气氛评分较对照组均有明显升高(P<0.05)。结论采用双语教学模式可以提高“新医科”背景下“5+3”一体化医学生的专业英语水平、英文学习能力和对学术认知,采用双语教学对提高泌尿外科规培带教质量有积极的意义。 展开更多
关键词 双语教学 “5+3”一体化 规培 泌尿外科 新医科
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不同生物炭处理对福建柏光合荧光特性的影响 被引量:9
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作者 凡莉莉 muhammad Waqqas khan Tarin +3 位作者 张洋洋 吴晓莹 荣俊冬 郑郁善 《中南林业科技大学学报》 CAS CSCD 北大核心 2021年第3期37-44,共8页
【目的】以一年生福建柏实生苗为研究对象,探究不同生物炭处理下福建柏光合作用变化规律,选择适宜的生物炭处理,为福建柏引种栽培和推广应用提供科学依据。【方法】选择竹炭(BB)、硬木(BH)和水稻(BR)3种生物炭,设置3种用量处理(5、20和8... 【目的】以一年生福建柏实生苗为研究对象,探究不同生物炭处理下福建柏光合作用变化规律,选择适宜的生物炭处理,为福建柏引种栽培和推广应用提供科学依据。【方法】选择竹炭(BB)、硬木(BH)和水稻(BR)3种生物炭,设置3种用量处理(5、20和80 g·kg^(-1))和对照组(0 g·kg^(-1),B_(0)),测定福建柏光合参数和叶绿素荧光参数,通过主成分分析法对生物炭施用效果进行综合评价。【结果】1)在BB和BR处理下,随用量增加,福建柏叶片净光合速率(P_(n))、气孔导度(G_(s))、胞间CO_(2)浓度(C_(i))和蒸腾速率(T_(r))4个参数变化趋势一致;水分利用效率(WUE)在BR处理与其它参数表现相同;相同用量生物炭处理下,5个光合指标均表现为在BB处理最高,其次是BH处理,BR处理最低。2)不同生物炭处理下福建柏叶绿素荧光参数变化趋势不同;随用量增加,BB、BH和BR处理下初始荧光值(F_(o))、PSⅡ实际光化学效率(Yield)和光合电子传递速率(ETR)3个参数呈波动升高趋势;PSII最大光化学效率(F_(v)/F_(m))、光化学荧光淬灭系数(qP)和非光化学淬灭系数(NPQ)呈波动升降趋势;除F_(o)外,3个处理中其它5个荧光参数均高于B0。3)P_(n)、G_(s)、C_(i)和T_(r)相关性强,主成分分析表明这4个光合参数是反映生物炭施用效果的重要光合生理指标;生物炭施用综合评价结果表明BB80和BB20处理效果最佳。【结论】20和80 g·kg^(-1)的竹子生物炭施用效果最佳,对福建柏光合荧光特性具有积极影响,可以在福建柏栽培中推广应用。 展开更多
关键词 生物炭 福建柏 光合特性 叶绿素荧光特性
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不同炭化温度的稻壳炭对稻壳炭/高密度聚乙烯复合材料的影响 被引量:7
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作者 张庆法 muhammad Usman khan +3 位作者 张东红 雷寒武 林晓娜 蔡红珍 《高分子材料科学与工程》 EI CAS CSCD 北大核心 2020年第7期67-72,共6页
为了考察不同炭化温度的稻壳炭对稻壳炭/高密度聚乙烯(HDPE)复合材料性能的影响,利用马弗炉制备了不同炭化温度(200℃,300℃,400℃,500℃,600℃)的稻壳炭,以该稻壳炭为填料,采用注塑成型的方法制备了稻壳炭/HDPE复合材料,并对其性能进... 为了考察不同炭化温度的稻壳炭对稻壳炭/高密度聚乙烯(HDPE)复合材料性能的影响,利用马弗炉制备了不同炭化温度(200℃,300℃,400℃,500℃,600℃)的稻壳炭,以该稻壳炭为填料,采用注塑成型的方法制备了稻壳炭/HDPE复合材料,并对其性能进行对比分析。傅里叶变换红外光谱与扫描电镜分析表明,600℃炭化温度的稻壳炭的极性最低,孔结构最完善;熔融结晶分析表明,稻壳炭的加入有利于提高HDPE的相对结晶度;力学性能与动态力学热分析表明,600℃炭化温度的稻壳炭/HDPE复合材料的弯曲强度(45.37 MPa)、刚性及弹性最强,但是不同炭化温度的稻壳炭对稻壳炭/HDPE复合材料的拉伸强度影响不大。 展开更多
关键词 炭化温度 稻壳炭 复合材料 高密度聚乙烯
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Views of South Asian Physicians on Climate Related Health Effects: A Multinational Cross-Sectional Pilot Study
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作者 Tehzeeb Zulfiqar Hina Jawaid +8 位作者 Abdul Jalil khan N. Waseem Ahmed Asif Rehman muhammad Hassam khan Kinley Bhutti Md. Ferdous Rahman Saadia Mustafa Husnulmaab Ali Tariq Aziz 《American Journal of Climate Change》 2023年第1期58-79,共22页
Background: South Asian populations are vulnerable to poor health outcomes associated with climate due to the region’s complex topography, poverty, lack of education, and population density. Physicians, being highly ... Background: South Asian populations are vulnerable to poor health outcomes associated with climate due to the region’s complex topography, poverty, lack of education, and population density. Physicians, being highly trusted members of society, can help mitigate climate change effects in their countries. Objectives: The present study assessed perceptions of physicians from four South Asian countries (Bangladesh, Bhutan, India, and Pakistan). We hypothesized that physicians from these countries will be aware and knowledgeable about health effects of climate change. Methods: We conducted a cross-sectional online survey of physicians between March and July 2022. Data of 201 physicians was analyzed using the Kruskal-Wallis test and Dunn’s post hoc method. Results: Physicians from four South Asian countries were attuned to the health risks associated with climate change. A majority of physicians (86.6%) believed that climate change would make health conditions in their countries more severe or frequent (Bangladesh 83.3%;Bhutan 70%;India 91% and Pakistan 90.8%). The most common health effect related to climate change was illnesses related to reduced outdoor air quality (54.3%). Common barriers to discuss climate change with patients from all four countries were physicians’ lack of knowledge (strongly agree, 13.8%;agree 47.7%) in how to approach the issue with patients, lack of time (strongly agree, 12%;agree, 48%) and their perception that patients were not interested in knowing about climate change (strongly agree, 8.6%;agree, 42.6%). More than half (56.2%) of the physicians reported no training (Bangladesh, 51.7%;Bhutan, 80%;India, 44.6%;Pakistan, 63.1%) and approximately 30% reported less than 20 hours of training (Bangladesh, 28.3%;Bhutan, 15.0%;India, 39.3%;Pakistan, 27.7%) in climate-change-related health effects. Conclusion: While additional large-scale research is needed to understand the trends observed in our pilot study, our findings identify the need to introduce interventions to improve physicians’ 展开更多
关键词 Climate Change Health PHYSICIANS South Asia
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Water Quality Evaluation of Chapurson Valley in Hunza Nagar, Gilgit Baltistan, Pakistan, Based on Statistical Analysis and Water Quality Index
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作者 Syeda Urooj Fatima Moazzam Ali khan +4 位作者 Aamir Alamgir Nasir Sulman Tariq Masood Ali khan Faisal Ahmed khan muhammad Azhar khan 《Health》 CAS 2023年第5期379-396,共18页
Water borne ailments are of serious public health concern in Gilgit Baltistan’s (GB) region of Pakistan. The pollution load on the glacio-fluvial streams and surface water resources of the Chapurson Valley in the Hun... Water borne ailments are of serious public health concern in Gilgit Baltistan’s (GB) region of Pakistan. The pollution load on the glacio-fluvial streams and surface water resources of the Chapurson Valley in the Hunza Nagar area of the GB is increasing as a result of anthropogenic activities and tourism. The present study focuses on the public health quality of drinking water of Chapurson valley. The study addressed the fundamental drinking water quality criteria in order to understand the state of the public health in the valley. To ascertain the current status of physico-chemical, metals, and bacteriological parameters, 25 water samples were collected through deterministic sampling strategy and examined accordingly. The physico-chemical parameters of the water samples collected from the valley were found to meet the World Health Organization (WHO) guidelines of drinking water. The water samples showed a pattern of mean metal concentrations in order of Arsenic (As) > Lead (Pb) > Iron (Fe) > Zinc (Zn) > Copper (Cu) > Magnesium (Mg) > Calcium (Ca). As, Cu, Zn, Ca and Mg concentration were under the WHO guidelines range. However, results showed that Pb and Fe are present at much higher concentrations than recommended WHO guidelines. Similarly, the results of the bacteriological analysis indicate that the water samples are heavily contaminated with the organisms of public health importance (including total coliforms (TCC), total faecal coliforms (TFC) and total fecal streptococci (TFS) are more than 3 MPN/100mL). Three principal components, accounting for 48.44% of the total variance, were revealed using principal component analysis (PCA). Bacteriological parameters were shown to be the main determinants of the water quality as depicted by the PCA analysis. The dendrogram of Cluster analysis using the Ward’s method validated the same traits of the sampling locations that were found to be contaminated during geospatial analysis using the Inverse Distance Weight (IDW) method. Based on these findings, it is most l 展开更多
关键词 Chapurson Valley Water Quality PHYSICO-CHEMICAL Principal Component Analysis (PCA) Inverse Distance Weight (IDW)
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作物化感作用类型:中国研究现状及其展望 被引量:3
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作者 林志敏 muhammad Umar khan +1 位作者 方长旬 林文雄 《中国生态农业学报(中英文)》 CAS CSCD 北大核心 2022年第3期343-355,共13页
本文从作物种内互作和种间互作以及直接化感作用和间接化感作用两个维度重点阐述了近年来中国在作物化感作用类型的研究及其新进展,以期与同行分享该领域的研究成果和经验。早在1984年就有作物化感作用的相关报道,近年来取得了很大的进... 本文从作物种内互作和种间互作以及直接化感作用和间接化感作用两个维度重点阐述了近年来中国在作物化感作用类型的研究及其新进展,以期与同行分享该领域的研究成果和经验。早在1984年就有作物化感作用的相关报道,近年来取得了很大的进展。作物化感作用的概念也延伸到植物-土壤-微生物相互之间的化感作用,作物种植体系中存在的偏害、自毒和促进等现象均与此有关。最近的研究表明,供体植物通过触发防御基因的表达,使代谢产物(化感物质)释放到环境中,尤其是土壤环境中作物的根系等对靶标植物(如杂草)的胁迫做出响应,从而在栽培系统中产生化感偏害或化感偏利现象。根据作用对象的不同,作物化感偏害和偏利现象分为种间和种内的相互作用两种类型。种间作用包括抑制和互惠作用,化感物质的种类、含量及其生物效应决定了其对邻近物种的化感效应;种内作用包括促进和自毒作用,即化感正效应和化感负效应。化感正效应或负效应均与根系分泌物介导的根际土壤微生物组成和结构的变化有关。连续单一化种植导致的病原菌增多、有益菌减少,土壤微生物结构失衡可引起化感负效应。这种微生物结构失衡不可避免地导致土壤养分封存、土壤酸化和土传病害发生等,从而导致作物产量和品质下降。化感正效应则与之相反,连作促进了有益菌群的增加和致病微生物的减少,提高了微生物多样性,从而改善土壤微生境,提高作物产量和品质。因此,研究根际土壤微生物的结构与功能,合理调控作物根际生境以保证其高产优质,促进农业可持续发展,将是今后研究的重点。 展开更多
关键词 作物化感作用 偏害 偏利 作用模式 土壤微生物
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巴基斯坦西瓦里克道克派珊组豕脊齿象属(长鼻目)新材料(英文)
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作者 Sayyed Ghyour ABBAS muhammad Akbar khan +2 位作者 muhammad Adeeb BABAR muhammad HANIF muhammad AKHTAR 《古脊椎动物学报》 CSCD 北大核心 2018年第4期295-305,共11页
褶齿豕脊齿象(Choerolophodon corrugatus)是豕脊齿象属在巴基斯坦西瓦里克群发现的唯一种。其首次发现是在西瓦里克亚群下部的卡米列组(中新世晚期),而后大量见于西瓦里克亚群中段的道克派珊组(中新世晚期至上新世早期)。本次报道的褶... 褶齿豕脊齿象(Choerolophodon corrugatus)是豕脊齿象属在巴基斯坦西瓦里克群发现的唯一种。其首次发现是在西瓦里克亚群下部的卡米列组(中新世晚期),而后大量见于西瓦里克亚群中段的道克派珊组(中新世晚期至上新世早期)。本次报道的褶齿豕脊齿象新材料发现于道克派珊模式产地及其邻近区域。发现的材料包括象牙、下颌、上颌碎片以及一些乳前臼齿和臼齿。新材料与欧洲的Ch. pentelici的牙齿特征极其相似,但在头骨和下颌特征上有所区别。 展开更多
关键词 西瓦里克群 道克派珊组 中新世 上新世 豕脊齿象属
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Quantitative Behaviour of Guar (Cymopsis tetragnolobus L.) to Various Tillage Systems and Mulches and Soil Physical Properties
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作者 M. ShahidIbni Zamir muhammad Aamir khan +9 位作者 Mazhar Hussain Ihtishamul Haq M. Kamran khan Qamaruz Zaman Usman Afzal Naveed Islam M. Asim Ihtisham Ali Husnain khan Khalid Iqbal 《American Journal of Plant Sciences》 2016年第7期1040-1045,共6页
A field study was conducted to evaluate the effect of organic mulches and tillage practices on growth, yield of cluster bean and soil physical properties. Experiment was comprised of two factors: A (Tillage), B (Mulch... A field study was conducted to evaluate the effect of organic mulches and tillage practices on growth, yield of cluster bean and soil physical properties. Experiment was comprised of two factors: A (Tillage), B (Mulches). Factor A was assigned to main plot and consisted of two treatments (Minimum tillage and Conventional tillage). Factor B was assigned to sub plot and consisted of four treatments (no mulch, wheat straw mulch, grass clipping mulch and saw dust mulch). The mulching materials were partially incorporated in the field after germination of crop. The experiment was laid out in Randomized Complete Block Design (RCBD) with split plot arrangement having three replications. Control treatment was kept for comparison. All other agronomic practices were kept standardized and consistent for all the treatments. Data regarding growth and yield components were collected and analyzed statistically by fisher analysis of variance and treatment significance was measured by significant difference test at 5% probability level. The factors, tillage and mulches significantly affected growth, yield, yield parameters and soil physical properties. Maximum plant population (31.7 m<sup>2</sup>), plant height (159 cm), branches per plant (18.9), cluster per plant (15.88), grains per pod (7.3), 1000-grain weight (34.6 g), grain yield (1.9 t&bull;ha<sup>-1</sup>), biological yield (9.91 t&bull;ha<sup>-1</sup>) and harvest index (19.15) was recorded in conventional tillage comparative to minimum tillage. Mulches also affected grain yield, and maximum grain yield was recorded in wheat straw mulch (1.88 t&bull;ha<sup>-1</sup>) followed by grass clipping mulch (1.81 t&bull;ha<sup>-1</sup>) and saw dust mulch (1.76 t&bull;ha<sup>-1</sup>) while minimum grain yield was recorded in control without mulch application (1.67 t&bull;ha<sup>-1</sup>). Tillage and mulches interactively affect pH, soil organic matter contents, electrical conductivity and soil bulk density. Mulches and minimum tillage improved soil physical properties. Highest B 展开更多
关键词 GUAR MULCH TILLAGE Soil Properties
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