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经颅磁声电刺激对健康与帕金森病大鼠神经回路中beta振荡的影响 被引量:1
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作者 张帅 由胜男 +2 位作者 杜文静 王磊 徐桂芝 《中国组织工程研究》 CAS 北大核心 2024年第16期2519-2526,共8页
背景:经颅磁声电刺激是一种基于磁声耦合电效应的无创、高精度脑神经聚焦刺激方法,可调节神经节律振荡活动,从而影响大脑的运动、认知等功能。目的:探究经颅磁声电刺激对健康与帕金森病大鼠神经回路中beta振荡的影响。方法:①动物实验:... 背景:经颅磁声电刺激是一种基于磁声耦合电效应的无创、高精度脑神经聚焦刺激方法,可调节神经节律振荡活动,从而影响大脑的运动、认知等功能。目的:探究经颅磁声电刺激对健康与帕金森病大鼠神经回路中beta振荡的影响。方法:①动物实验:采用随机数字表法将24只Wistar大鼠随机分为4组,每组6只:正常对照组不进行任何干预;正常刺激组大脑前额叶皮质接受经颅磁声电刺激(空间峰值脉冲平均强度为13.33 W/cm^(2),基波频率为0.4 MHz,基波周期数为1000,脉冲重复频率为200 Hz);模型对照组、模型刺激组通过腹腔注射1-甲基-4-苯基-1,2,3,6-四氢吡啶建立帕金森病模型,造模成功后,模型对照组大脑前额叶皮质接受经颅磁声电假刺激,模型刺激组大脑前额叶皮质接受经颅磁声电刺激,每天刺激时长2.0 min,刺激结束停留8-10 min后,采集大鼠执行T迷宫过程中局部场电位信号并同时记录行为学正确率,对比分析各组局部场电位信号能量的时频分布情况和行为差异,当大鼠正确率连续3 d高于80%后停止刺激实验和T迷宫实验。②建模仿真实验:构建经颅磁声电刺激下皮质-基底神经节回路模型,分别改变超声发射周期(5,10,20 ms)、超声发射占空比(30%,50%,90%)和感应电流密度(20,50,100μA/cm^(2)),比较不同刺激参数下健康与帕金森病大鼠beta振荡的功率谱密度值。结果与结论:①动物实验:正常对照组大鼠的空间学习能力强于模型对照组(P<0.001),正常刺激组大鼠的空间学习能力强于正常对照组(P<0.05),模型刺激组大鼠的空间学习能力强于模型对照组(P<0.01);正常对照组beta振荡能量分布较为集中,正常刺激组较正常对照组beta振荡信号能量有所降低,模型对照组与模型刺激组beta振荡能量广泛分布且能量值显著高于正常对照组、正常刺激组,并且模型刺激组beta振荡信号能量明显低于模型对照组;②建模仿真实验:不加刺激时,健康大鼠beta频段功率谱密度峰值(30 dB)显著低于帕金森病大鼠(55 dB);施加经颅磁声电刺激后,两组大鼠beta频段功率谱密度值普遍降低;beta频段功率谱密度峰值与超声发射周期呈正相关、与感应电流密度呈负相关,当超声发射占空比为50%时功率谱密度峰值最低;③结果表明:经颅磁声电刺激可抑制健康与帕金森病大鼠的beta振荡,进而改善大鼠的运动功能与决策认知功能。 展开更多
关键词 经颅磁声电刺激 皮质-基底神经节回路 beta振荡 帕金森病 局部场电位 T迷宫 神经调控
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基于Beta分布的目标搜索概率自适应更新策略及其应用
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作者 高瑞周 孔金涛 +1 位作者 汤陈 彭秀辉 《电光与控制》 CSCD 北大核心 2024年第11期102-108,共7页
针对不确定先验信息条件下的目标搜索问题,考虑传感器探测概率和虚警概率,设计了基于Beta分布的目标搜索概率自适应更新策略。首先,通过Beta分布建立了不确定先验环境的概率地图,并提出自适应目标搜索概率更新策略,使得无人机能够根据... 针对不确定先验信息条件下的目标搜索问题,考虑传感器探测概率和虚警概率,设计了基于Beta分布的目标搜索概率自适应更新策略。首先,通过Beta分布建立了不确定先验环境的概率地图,并提出自适应目标搜索概率更新策略,使得无人机能够根据概率信息图动态更新检测次数;其次,在概率更新策略中引入了拒绝概率修正因子,根据地图概率差动态调整概率变化量,避免了搜索任务中可能存在的误检漏检问题;最后,通过数值仿真实验,验证了提出的目标搜索自适应更新策略可在不影响搜索效率的前提下,有效减小无人机的错误检测概率。 展开更多
关键词 协同搜索 动态变化环境 beta分布 自适应概率更新
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Iron dysregulation in beta-thalassemia 被引量:4
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作者 Kamonlak Leecharoenkiat Pathrapol Lithanatudom +1 位作者 Wannapa Sornjai Duncan R.Smith 《Asian Pacific Journal of Tropical Medicine》 SCIE CAS 2016年第11期1013-1021,共9页
Iron deficiency anemia and iron overload conditions affect more than one billion people worldwide.Iron homeostasis involves the regulation of cells that export iron into the plasma and cells that utilize or store iron... Iron deficiency anemia and iron overload conditions affect more than one billion people worldwide.Iron homeostasis involves the regulation of cells that export iron into the plasma and cells that utilize or store iron.The cellular iron balance in humans is primarily mediated by the hepcidin-ferroportin axis.Ferroportin is the sole cellular iron export protein,and its expression is regulated transcriptionally,post-transcriptionally and posttranslationally.Hepcidin,a hormone produced by liver cells,post-translationally regulates ferroportin expression on iron exporting cells by binding with ferroportin and promoting its internalization by endocytosis and subsequent degradation by lysosomes.Dysregulation of iron homeostasis leading to iron deposition in vital organs is the main cause of death in betathalassemia patients.Beta-thalassemia patients show marked hepcidin suppression,ineffective eiythropoiesis,anemia and iron overload.Beta-thalassemia is common in the Mediterranean region,Southeast Asia and the Indian subcontinent,and the focus of this review is to provide an update on the factors mediating hepcidin related iron dysregulation in beta-thalassemia disease.Understanding this process may pave the way for new treatments to ameliorate iron overloading and improve the long term prognosis of these patients. 展开更多
关键词 beta-thalassemia HEPCIDIN Iron overload FERROPORTIN
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Effectiveness of Using Mean Corpuscular Volume and Mean Corpuscular Hemoglobin for Beta-thalassemia Carrier Screening in the Guangdong Population of China 被引量:4
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作者 GU Heng WANG Yong Xia +3 位作者 DU Meng Xuan XU Shan Shan ZHOU Bing Yi LI Ming Zhen 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2021年第8期667-671,共5页
Beta(β)-thalassemia is one of the most common hemoglobinopathies worldwide,creating major public health problems and social burdens in many regions.Screening forβ-thalassemia carriers is crucial for controlling this... Beta(β)-thalassemia is one of the most common hemoglobinopathies worldwide,creating major public health problems and social burdens in many regions.Screening forβ-thalassemia carriers is crucial for controlling this condition.To investigate the?effectiveness?of?mean?corpuscular?volume?(MCV)and mean corpuscular hemoglobin(MCH)for screeningβ-thalassemia,retrospective data were analyzed for 6,779β-thalassemia carriers subjected to genetic testing following thalassemia screening in Guangdong province between January 2018 and December 2019. 展开更多
关键词 GUANGDONG POPULATION thalassemia
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草甸草原植物beta多样性高光谱遥感估算方法
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作者 杨星晨 雷少刚 +4 位作者 徐军 苏兆瑞 王维忠 宫传刚 赵义博 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2024年第6期1751-1761,共11页
目前,全球生物多样性的状态非常堪忧,因此,利用光谱技术估算生物多样性成为了生态学家和遥感学家共同关注的热点。目前关于植物alpha多样性的研究很多,而关于beta多样性的研究较少,仍存在一些问题值得去探索。为了探究利用遥感技术估算... 目前,全球生物多样性的状态非常堪忧,因此,利用光谱技术估算生物多样性成为了生态学家和遥感学家共同关注的热点。目前关于植物alpha多样性的研究很多,而关于beta多样性的研究较少,仍存在一些问题值得去探索。为了探究利用遥感技术估算植物beta多样性的最佳光谱指数以及最佳影像空间分辨率,以草甸草原为研究区,基于无人机高光谱遥感影像,从光谱距离、光谱角度、生物多样性概念三个方面计算了6种beta多样性估算指数(4种为我们构建的新指数,2种为已有的指数),并采用Mantel tests和相关系数筛选最佳的光谱指数。然后将筛选出来的指数应用于不同空间分辨率的影像,以期得到最佳观测尺度。另外,为了提高指数的估算能力,对比了一阶导数变换和Savitzky-Golay滤波两种光谱变换方法,以及相关系数法、连续投影法、竞争性自适应重加权法三种特征波段选择方法。结果表明,不论是采用亚尺度观测(像元大小<样方大小)还是等尺度观测(像元大小=样方大小),最佳的光谱指数均为光谱距离指数,且光谱距离指数在不同影像空间分辨率下均表现良好。在草原地区,当影像空间分辨率约为0.25 m时,该指数可以取得最佳的估算结果。经一阶导数变换并用相关系数法提取特征波段后构建的光谱距离指数与beta多样性拥有最强的相关性,今后可利用该指数构建估算模型或者直接表征beta多样性。该研究对于科学的选取光谱指数和影像空间分辨率去估算植物beta多样性具有一定的指导意义。 展开更多
关键词 beta多样性 高光谱遥感 光谱指数 观测尺度 光谱曲线
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晶种辅助蒸气转化Al-SBA-15合成Beta纳米晶团聚体
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作者 孙琳 林森 王润伟 《高等学校化学学报》 SCIE EI CAS CSCD 北大核心 2024年第8期35-42,共8页
采用晶种辅助蒸气转化(SASC)策略,将有序介孔分子筛Al-SBA-15颗粒直接转化为Beta纳米晶团聚体(BNA).除规则微孔外,BNA含有2种多级介孔结构.研究了骨架组装与多级孔结构的关系.通过调节热分解条件,将P123胶束选择性分解成碳颗粒并分散于A... 采用晶种辅助蒸气转化(SASC)策略,将有序介孔分子筛Al-SBA-15颗粒直接转化为Beta纳米晶团聚体(BNA).除规则微孔外,BNA含有2种多级介孔结构.研究了骨架组装与多级孔结构的关系.通过调节热分解条件,将P123胶束选择性分解成碳颗粒并分散于Al-SBA-15介孔中,在颗粒内部构建了均匀的三维纳米空间网格.通过浸渍Beta晶种和四乙基铵阳离子(TEA+)强化分子筛成核,采用蒸气处理方法,将Al-SBA-15无定形孔壁在纳米空间中缓慢转化为Beta纳米晶体.通过调节合成参数,使纳米晶体沿Al-SBA-15孔壁方向规则排列,形成有序介观结构.此外,经高温焙烧去除碳颗粒后,BNA内部生成了穴状介孔.实验结果表明,低的溶剂用量可显著降低传质速度,提高骨架组装质量,从而使BNA酸性增强.优异的多级孔结构和较强的酸性使BNA在大分子反应中具有应用潜力. 展开更多
关键词 多级孔beta纳米晶 Al-SBA-15 晶种辅助蒸气转化 骨架组装
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The Prevalence of Adrenal, Parathyroid and Cardiac Dysfunction in Patients with Beta Thalassemia Major
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作者 Najat E. Mahdi Taysir S. Garadah +2 位作者 Zuheir Hassan Ahmed A. Jaradat Das S. Nagalla 《International Journal of Clinical Medicine》 2013年第7期325-330,共6页
Background: Adrenal and parathyroid insufficiency are uncommon in patients with transfusion dependent Beta Thalassemia (β-TM). Further, myocardial echocardiographic abnormalities are recognized but with a variable ou... Background: Adrenal and parathyroid insufficiency are uncommon in patients with transfusion dependent Beta Thalassemia (β-TM). Further, myocardial echocardiographic abnormalities are recognized but with a variable outcomes Aim: The aim is to determine the prevalence of adrenal and parathyroid insufficiency in patient with transfusion dependent β-TM. And to assess left ventricle systolic and diastolic function using Pulsed Doppler (PD) and Tissue Doppler (DT) echocardiogram. Methods:The study was conducted on patients with β-TM (n = 99, age 15.92 ± 8.92 years) and compared with an age-matched controls (n = 98 age 15.79 ± 8.94 years). In all participants echocardiographic indices of M mode and PD and TD were performed. Blood samples were withdrawn for measuring the serum cortisol, parathyroid and Ferritin. Correlation between the level of cortisol and ferritin level was evaluated. Results: Patients with β-TM compared with controls, had significantly thicker LV septal wall index of 0.65 ± 0.26 vs 0.44 ± 0.2190, p 0.001 and LV posterior wall of 0.65 ± 0.235 vs 0.43 ± 0.214, p ± 5.5 vs 5.0 ± 5.6, p = 0.23. Furthermore patients with β-TM had higher E/A ratio (1.54 ± 0.18 vs 1.23 ± 0.17, p 0.01) and shorter deceleration time (DT) (170.53 ± 13.3 vs 210.50 ± 19.20 m sec, p 0.01). The ratio of transmitral E wave velocity to the tissue Doppler E wave at the basal septal mitral annulus (E/Em) was significantly higher in β-TM group (19.68 ± 2.81 vs 13.86 ± 1.41, p 0.05). The tissue Doppler systolic wave (Sm) velocity and the early diastolic wave (Em) were significantly lower in β-TM group compared with controls with Sm, of 4.82 ± 1.2 vs 6.22 ± 2.1 cm/sec, p 0.05 and (Em) of 3.51 ± 2.7 vs 4.12 ± 2.5 cm/sec p 0.05, respectively). The tricuspid valve velocity was significantly higher in β-TM patients compared with controls (2.85 ± 0.56 vs 1.743 ± 0.47 m/sec, respectively, p 0.01). The prevalence of adrenal insufficiency in patients with β-TM was 16%, hypoparathyroidism of 4.5% weak negative correlation between serum level of cortisol and the serum Ferritin. Conclusion: Patients with β-thalassemia major had a high prevalence of subclinical adrenal insufficiency of 16%, hypoparathyroidism of 4.5% with weak negative correlation between the low level of cortisol ≤160 nmol/L and high serum ferritin. Echocardiographic Pulsed Doppler showed a restrictive LV diastolic pattern suggestive of advanced diastolic dysfunction but preserved left ventricle systolic function. 展开更多
关键词 CORTISOL Hormone beta-thalassemia MAJOR Pulsed Echo DOPPLER Tissue DOPPLER Echocardiography Bahrain
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Beta@ZIF-67复合材料的制备及对聚乳酸塑料的催化降解性能
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作者 王晨竹 高明坤 +2 位作者 高艳静 齐思贤 于吉红 《高等学校化学学报》 SCIE EI CAS CSCD 北大核心 2024年第9期16-24,共9页
以聚乳酸(PLA)为代表的可降解塑料被认为是传统石油基塑料的合适替代品.然而,PLA自然降解的时间较长,同时伴随着CO_(2)的排放.因此,升级回收PLA更有利于实现可持续发展.本文通过将沸石咪唑酯骨架(ZIF-67)生长在Beta沸石表面,制备了一种B... 以聚乳酸(PLA)为代表的可降解塑料被认为是传统石油基塑料的合适替代品.然而,PLA自然降解的时间较长,同时伴随着CO_(2)的排放.因此,升级回收PLA更有利于实现可持续发展.本文通过将沸石咪唑酯骨架(ZIF-67)生长在Beta沸石表面,制备了一种Beta@ZIF-67复合材料.该材料可以实现废弃PLA塑料的高效催化降解,在180℃下反应4 h即可将日常生活中所用PLA塑料完全转化为乳酸甲酯(产率高达76.4%).这种高催化效率得益于复合材料开放的孔道结构和较大的比表面积,以及ZIF-67(Lewis酸/碱)与Beta分子筛(Brønsted酸)所提供活性位点的协同作用.本研究为沸石分子筛复合催化剂的设计合成及用于聚乳酸塑料催化降解提供了新的途径. 展开更多
关键词 beta沸石 沸石咪唑酯骨架 聚乳酸 催化降解
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高原鼠兔干扰对高寒草甸植物物种和功能性状beta多样性的影响
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作者 李捷 孙文涛 +3 位作者 庞晓攀 徐雪婷 杨欢 郭正刚 《生态学报》 CAS CSCD 北大核心 2024年第7期2993-3003,共11页
采用野外空间多点同步取样,分析了高原鼠兔干扰对高寒草甸植物物种beta多样性和植物功能性状beta多样性的影响,确定了高原鼠兔干扰下高寒草甸植物物种和功能性状beta多样性的变化途径,分别提出了高原鼠兔干扰区域内,基于植物物种多样性... 采用野外空间多点同步取样,分析了高原鼠兔干扰对高寒草甸植物物种beta多样性和植物功能性状beta多样性的影响,确定了高原鼠兔干扰下高寒草甸植物物种和功能性状beta多样性的变化途径,分别提出了高原鼠兔干扰区域内,基于植物物种多样性和功能性状多样性的高寒草甸植物多样性维持策略。结果表明,高原鼠兔干扰使高寒草甸植物物种相似性显著降低了28.1%,植物功能相似性降低了28.7%。尽管高原鼠兔干扰没有改变高寒草甸植物物种和功能性状beta多样性的变化途径,且对植物物种和功能性状的嵌套组分不存在显著影响,但高原鼠兔干扰显著降低了植物物种和功能性状周转组分所占的比例,降幅分别为36.6%和34.3%。高原鼠兔干扰区域内,高寒草甸植物物种beta多样性的变化以周转为主导(周转占比81.4%;嵌套占比:18.6%),植物功能性状beta多样性的变化以嵌套为主导(嵌套占比64.9%;周转占比35.1%)。因此,针对划定的高原鼠兔干扰区,需要同时保护区域内所有高原鼠兔栖息地(多位点保护),以达到维持植物物种多样性的目的,而可以仅通过保护该区域内植物功能性状丰富的位点,即可维持较高的植物功能多样性。 展开更多
关键词 高寒草甸 功能性状beta多样性 干扰 物种周转 主坐标分析
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响应面模型用于Beta分子筛催化剂蜂窝状整体式成型的研究
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作者 韩莹莹 王宁 +1 位作者 陈标华 徐瑞年 《石油炼制与化工》 CAS CSCD 北大核心 2024年第6期83-91,共9页
Beta分子筛由于具有独特的三维十二元环孔道结构,可提供更多活性组分附着位点,是在实际应用中具有优异性能的工业催化剂。在工业使用中,蜂窝整体式催化剂具有通量高、流场均匀、压降小、不易堵塞的优点,是气固或者液固催化反应的最优解... Beta分子筛由于具有独特的三维十二元环孔道结构,可提供更多活性组分附着位点,是在实际应用中具有优异性能的工业催化剂。在工业使用中,蜂窝整体式催化剂具有通量高、流场均匀、压降小、不易堵塞的优点,是气固或者液固催化反应的最优解决方案。但由于Beta分子筛吸水率高,收缩率大,导致蜂窝成型困难,严重限制了Beta分子筛的工业应用。基于此,选择拟薄水铝石(SB粉)为黏结剂、硝酸为胶溶剂、田菁粉为助挤剂,在水粉比为0.6的条件下制备一系列蜂窝整体式成型Beta分子筛催化剂,基于响应面法,评价了各原料的配比对蜂窝整体式催化剂机械强度的影响,得到了催化剂的机械强度与3个因素(黏结剂用量、胶溶剂用量、助挤剂用量)之间关系的二阶多项式近似模型函数。将试验结果与预测值进行对比,证明了预测模型的可靠性,并利用该模型找到最优的Beta分子筛蜂窝成型条件为SB粉质量分数36.1%、硝酸质量分数8.4%、田菁粉质量分数4.7%。 展开更多
关键词 beta分子筛 蜂窝整体式催化剂 响应面法
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Laboratory Indicators and Some Considerations in Albanian Patients with Beta Thalassemia Major and Sickle Cell Disease
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作者 Manika Kreka Eleni Nastas +4 位作者 Etleva Refatllari Alma Idrizi Vjollca Shpata Bledi Kreka Anila Godo 《Journal of Biosciences and Medicines》 2022年第1期141-149,共9页
Haemoglobinopathies are very serious clinical conditions caused by genetic mutations. They belong to autosomal recessive disorders and the most frequent genetic inherited diseases seen, specifically and above all amon... Haemoglobinopathies are very serious clinical conditions caused by genetic mutations. They belong to autosomal recessive disorders and the most frequent genetic inherited diseases seen, specifically and above all among Mediterranean countries. Thalassaemia syndromes (included Beta Thalassaemia and Sickle Cell Disease) have been the first diagnosed diseases since in intrauterine life using reccombinant DNA techniques. So, the better understanding of their pathophysiology has given a spectacolar improvement and a considerable impact on these conditional managements. Every year there are nearly 300,000 children born with haemoglobinopathies globally, and there are 60,000 - 70,000 children with Beta Thalassemia among them. Nowadays in Albania like everywhere, there is a significant increase of survival in these patients. As a result of life longevity and improvement of patients life quality, we can see that these patients may suffer from other concomitant illnesses. In our country, there are registered approximately 500 patients with haemoglobinopathies. We studied 50 pediatric patients at random ranging from age 2 until 18 years old. We excluded other pathologies among them. We found high values of biochemical indicators in blood (Ca 15-3 was found elevated in 75% of our patients, Lactate Dehydrogenases was found elevated in 70% of cases, Indirect Bilirubin was found elevated in 66% of cases). All three parameters are indicators of hemolysis. We found a correlation between high values of Ca 15-3 marker and high levels of LDH, Indirect Bilirubin and low level of hemoglobin (p < 0.05). Ca 15-3 is much elevated among patients non regularly transfused and in those who take an unsufficient amount of blood. Continuous monitoring of these biochemical parameters is going to help in the more effective follow up of patients with haemoglobinopathies. 展开更多
关键词 TM—thalassemia Major TI—thalassemia Intermedia SCD—Sickle Cell Disease TSCD—thalassemia-Sickle Cell Disease LDH—Lactate Dehydrogenases Ca 15-3-Tumor Marker IB—Indirect Bilirubin PRBC—Pure Red Blood Cells Apoptosis-Programmed Death of the Cell
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Simple Red Cell Indices in Screening and Discrimination of Iron Deficiency Anemia and Beta Thalassemia Trait in Egyptian Patients
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作者 Elham O. Hamed Abeer Fakher El-Deen 《Open Journal of Blood Diseases》 2019年第1期9-19,共11页
Background: The most common causes of microcytic hypochromic anemia are iron deficiency anemia (IDA) and the beta-thalassemia trait (β-TT). The aim of the work is to compare the validity of the various simple indices... Background: The most common causes of microcytic hypochromic anemia are iron deficiency anemia (IDA) and the beta-thalassemia trait (β-TT). The aim of the work is to compare the validity of the various simple indices to differentiate between iron deficiency anemia and β-thalassemia trait. Subjects and methods: A total of 2000 individuals were screened, by complete blood picture, measurement of serum iron, serum ferritin and hemoglobin separation;224 patients were detected as having hypochromia and microcytosis. Among them 166 cases were IDA and 58 cases were β-TT. We calculated 11 discrimination indices. The number of correctly identified cases were determined, sensitivity, specificity, positive and negative predictive value and Youden’s index (YI) of each discrimination index was calculated. Results: The percentage of correctly diagnosed patients is highest for Matos and Carvalho index (MCI) (95.5%) which is closely followed by Red cell distribution width index (RDWI) (93.7%). The third high index was Green and King (GKI) (91.9%). Sensitivity, specificity of MCI for detection of IDA was found 98.8%, 87.9% respectively. For β-TT, sensitivity and specificity was found 86.2% and 98.8% respectively. The YI of MCI was found 85.9%. It is followed by RDWI;its sensitivity and specificity for detection of IDA was found 97.6%, 85.3%. For β-TT, sensitivity and specificity was found 82.7% and 97.6% respectively. The YI of RDWI was 81.6%. Conclusion: Matos and Carvalho index and RDWI are easily available automated cell-count-based indices coming out as good discriminator between IDA and β-TT in our study. 展开更多
关键词 thalassemia TRAIT Iron DEFICIENCY ANEMIA RBC Indices
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La掺杂改性Co-Beta催化丙烷脱氢
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作者 肖晗 邓维华 +4 位作者 林雨来 梁俊 董佳明 罗永明 何德东 《工业催化》 CAS 2024年第10期43-49,共7页
钴基催化剂在高温反应中易团聚烧结,且对其活性中心认识不足。为此设计了一种新型CoLa双金属催化剂,通过稀土金属La隔离并稳定钴物种,从而提高催化剂的反应活性。通过调控La在材料中的掺杂量,建立不同分散度与催化性能之间的构-效关系,... 钴基催化剂在高温反应中易团聚烧结,且对其活性中心认识不足。为此设计了一种新型CoLa双金属催化剂,通过稀土金属La隔离并稳定钴物种,从而提高催化剂的反应活性。通过调控La在材料中的掺杂量,建立不同分散度与催化性能之间的构-效关系,以深入了解活性中心。采用XRD、XPS、化学吸附、探针分子红外等表征手段对催化剂中Co物种的存在形式、化学环境和尺寸大小等催化相关性质进行分析。结果表明,La的掺杂可以促进Co物种的分散,并增强Co物种与载体之间的相互作用。 展开更多
关键词 催化化学 丙烷脱氢 钴基催化剂 稀土改性 beta沸石 协同作用
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Does Beta Thalassemia Increase the Incidence of Bell's Palsy?
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作者 Shahrazad S. AI Jebori 《Journal of Health Science》 2017年第3期135-138,共4页
A five-year old Iraqi patient with beta thalassemia major was presented with recurrent attack of Bell's palsy on 2 successive years being a milder one in the second year. This is a rare occurrence in beta thalassemia... A five-year old Iraqi patient with beta thalassemia major was presented with recurrent attack of Bell's palsy on 2 successive years being a milder one in the second year. This is a rare occurrence in beta thalassemia major patients and needs to be further explored. This is a case report of a nine-year old Iraqi child who is the only child born to parents of secondary consanguinity relatives from Babil Province who was diagnosed as beta thalassemia on the age of 6 months and is on regular blood transfusion and iron chelation therapy of deferasirox tablets (Exjade), his medical follow up takes place at Babil Thalassemia center in Babil Maternity and Child Hospital. On the age of five years, he was presented with a sudden onset of right sided Bell's palsy within twenty four hours of swimming in a cool swimming pool at his home in July 2011. A neurosurgeon examined him at that time, no investigations were done, the diagnosis was purely clinical, steroid & neurotonics were recommended as a treatment for the condition, antiviral agents were not prescribed, lacrimation & taste were not affected, there was a slow improvement, two weeks later physiotherapy sessions including facial massage ad electric stimulation were recommended after which the child improved. The next year, another attach of Bell's Palsy developed at a similar time with the same sequel of events, this time the attack was milder and with residual effects seen in the eye & mouth. This coincidence of beta thalassemia and Bell's palsy should be further studied by observational epidemiologic studies to prove or disprove the hypothesis that thalassemic patients especially children are at higher risk of developing Bell's palsy than healthy children. Beta thalassemia patients may be at higher risk of developing Bell's Palsy. 展开更多
关键词 B thalassemia major Bell's palsy Babil thalassemia center.
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基于Beta函数的温度分量模型在混凝土拱坝变形监控中的应用
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作者 胡恢武 杨威 +2 位作者 彭嘉畅 巫殷旺 卢祥 《大坝与安全》 2024年第3期35-40,56,共7页
混凝土拱坝由于具有特殊的超静定壳体结构,对温度尤其敏感,因此拱坝变形监控模型中的温度分量对模型综合性能有显著影响。使用常见的周期三角函数和平均温度等传统温度分量构建方法,无法很好地表示拱坝坝体内部的温度分布与外界温度的... 混凝土拱坝由于具有特殊的超静定壳体结构,对温度尤其敏感,因此拱坝变形监控模型中的温度分量对模型综合性能有显著影响。使用常见的周期三角函数和平均温度等传统温度分量构建方法,无法很好地表示拱坝坝体内部的温度分布与外界温度的滞后效应。因此,提出了一种新的温度滞后特性模拟方法,采用Beta分布来描述滞后影响,并基于Beta函数建立了混凝土拱坝变形监控模型。将基于Beta函数的温度分量模型应用于某拱坝变形监控模型的建立,结果表明监控模型的拟合精度和预测精度均优于传统模型,并表征了前期气温对沿拱向坝体测点变形的影响权重分布,描述了气温对坝体变形的滞后效应。 展开更多
关键词 混凝土拱坝 温度分量 beta函数 变形监控模型
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Pt/Beta催化剂上Pt金属中心/酸中心浓度比对加氢异构化性能的影响
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作者 郭凯 马爱增 +4 位作者 罗一斌 王子健 邢恩会 李金芝 李大东 《石油学报(石油加工)》 EI CAS CSCD 北大核心 2024年第1期12-22,共11页
以工业Beta沸石为载体,负载不同含量的Pt,得到了不同金属中心/酸中心浓度比(c_(M)/c_(A))的催化剂,对其进行物化表征,并以正庚烷为模型化合物对不同c_(M)/c_(A)催化剂进行异构化反应性能评价。结果表明:Pt粒子均匀地负载在沸石的外表面... 以工业Beta沸石为载体,负载不同含量的Pt,得到了不同金属中心/酸中心浓度比(c_(M)/c_(A))的催化剂,对其进行物化表征,并以正庚烷为模型化合物对不同c_(M)/c_(A)催化剂进行异构化反应性能评价。结果表明:Pt粒子均匀地负载在沸石的外表面上,对沸石结构没有影响,酸性略有下降。对于催化剂的正庚烷异构化反应活性,当催化剂c_(M)/c_(A)小于0.037时,反应过程由金属中心数量控制,产生大量多支链异构体产物和裂化产物;当c_(M)/c_(A)大于0.285时,反应过程由酸中心数量控制,有氢解反应发生。在反应压力为0.4 MPa、反应温度为207℃、质量空速为1.0 h^(-1)、氢/烃摩尔比为5、催化剂质量为1.0 g的条件下,当催化剂c_(M)/c_(A)为0.266、正庚烷转化率为70.75%时,异构体总选择性为95.14%,总收率为67.31%,其中多支链异构体收率为15.63%,裂化产物收率低于5%。 展开更多
关键词 beta沸石 异构化反应 Pt含量 正庚烷 金属中心 酸中心
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Do Endocrinopathies Differ in Most Prevalent Hemoglobinopathy of Middle East:Beta-thalassemia?
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作者 Salma Ahi Mohsen Adelpour +1 位作者 Bahareh Haghdoost Ali Jaberi 《Journal of Endocrinology Research》 2022年第2期10-16,共7页
Repeated blood transfusions in thalassemia patients is followed by endo-crinopathies as diabetes,hypothyroidism,hypogonadism,hypoparathy-roidism,and disorders in calcium and vitamin D homeostasis.The aim of this study... Repeated blood transfusions in thalassemia patients is followed by endo-crinopathies as diabetes,hypothyroidism,hypogonadism,hypoparathy-roidism,and disorders in calcium and vitamin D homeostasis.The aim of this study was to evaluate the association of beta-thalassemia patients endocrinopathies and osteoporosis.Serum level of some factors related to the function of gonads,thyroid,adrenal,and pancreas along with serum levels of calcium,phosphate,albumin,vitamin D,and iron were measured.Bone marrow density was tested via dualenergy x-ray absorptiometry(DXA densitometry).In this study,56 patients with major thalassemia were investigated.Paraclinical analysis indicated osteopenia in 17(30.4%)and osteoporosis in 39 patients(69.6%)in addition to other types of endocrine disorders,such as hypogonadism in 29(51.8%),hypothyroidism in 13(23.2%),hypoparathyroidism in 1(1.8%),hypocortisolism in 2(3.6%),and diabetes in 9(16.1%)patients.Endocrinopathies had no signifi cant relationship with osteoporosis and osteopenia in men.However,hypogonadism had a significant relationship with osteoporosis and osteopenia in women with thalassemia.Estradiol level was lower in women with osteoporosis in comparison with women with osteopenia.Ferritin levels had neither association with osteoporosis nor with LH levels(P>0.05).Secondary hypogonadism disorders are the main causes of osteoporosis and osteopenia in female beta-thalassemia patients. 展开更多
关键词 thalassemia OSTEOPOROSIS Bone mineral densitometry Endocrinopathies
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Deactivation mechanism of acetone to isobutene conversion over Y/Beta catalyst
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作者 Chang Wang Tingting Yan Weili Dai 《Chinese Journal of Catalysis》 SCIE CAS CSCD 2024年第9期133-142,共10页
The conversion of acetone derived from biomass to isobutene has attracted extensive attentions.In comparison with Brønsted acidic catalyst,Lewis acidic catalyst could exhibit a better catalytic performance with a... The conversion of acetone derived from biomass to isobutene has attracted extensive attentions.In comparison with Brønsted acidic catalyst,Lewis acidic catalyst could exhibit a better catalytic performance with a higher isobutene selectivity.However,the catalyst stability remains a key problem for the long-running acetone conversion and the reasons for catalyst deactivation are poorly understood up to now.Herein,the deactivation mechanism of Lewis acidic Y/Beta catalyst during the acetone to isobutene conversion was investigated by various characterization techniques,including acetone-temperature-programmed surface reaction,gas chromatography-mass spectrometry,in situ ultraviolet-visible,and ^(13)C cross polarization magic angle spinning nuclear magnetic resonance spectroscopy.A successive aldol condensation and cyclization were observed as the main side-reactions during the acetone conversion at Lewis acidic Y sites.In comparison with the low reaction temperature,a rapid formation and accumulation of the larger cyclic unsaturated aldehydes/ketones and aromatics could be observed,and which could strongly adsorb on the Lewis acidic sites,and thus cause the catalyst deactivation eventually.After a simple calcination,the coke deposits could be easily removed and the catalytic activity could be well restored. 展开更多
关键词 Deactivation mechanism Acetone to isobutene Lewis acid sites Y/beta Spectroscopy
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不同硅铝比Beta分子筛水蒸气动态吸附性能研究
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作者 张学勤 白洪灏 +2 位作者 唐轩 李世帅 杨江峰 《低碳化学与化工》 CAS 北大核心 2024年第11期90-96,共7页
硅铝沸石分子筛在吸附领域应用广泛,其亲、疏水性能对吸附性能影响较大,但硅铝沸石分子筛在不同条件下的水蒸气动态吸附性能尚不明确。采用不同硅铝比(n(SiO_(2))/n(Al_(2)O_(3))=30、135或679)的Beta分子筛(Beta-30、Beta-135和Beta-6... 硅铝沸石分子筛在吸附领域应用广泛,其亲、疏水性能对吸附性能影响较大,但硅铝沸石分子筛在不同条件下的水蒸气动态吸附性能尚不明确。采用不同硅铝比(n(SiO_(2))/n(Al_(2)O_(3))=30、135或679)的Beta分子筛(Beta-30、Beta-135和Beta-679)作为研究对象,先采用XRD、FT-IR和TG等对其进行了表征,然后在不同温度和相对湿度(HR)下分别进行了Beta-30、Beta-135和Beta-679的水蒸气吸附容量和相应动力学分析。结果表明,当温度为25℃或35℃、H_R小于80%时,Beta-679的吸附容量最低。当温度为15℃、HR为5%~10%时,Beta-679的平衡速率最快。当温度为15℃、H_R为50%~70%时,Beta-30、Beta-135和Beta-679的平衡速率表现出较大区别(Beta-135的平衡速率远小于Beta-30和Beta-679的平衡速率)。 展开更多
关键词 beta分子筛 硅铝比 水蒸气吸附 动力学
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异丁烷正构化Pt/Beta催化剂中Pt的作用研究
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作者 郭纬杨 张成喜 +1 位作者 邢恩会 慕旭宏 《石油学报(石油加工)》 EI CAS CSCD 北大核心 2024年第6期1537-1548,共12页
当前减油增化的大趋势下,正丁烷相比异丁烷在化工利用方面综合效益更高,近些年异丁烷正构化成为了学术界和工业界的关注热点。通过控制Pt负载量和负载位置研究了Pt负载沸石催化剂在异丁烷正构化反应中Pt的作用。结果表明:由于丁烷的异-... 当前减油增化的大趋势下,正丁烷相比异丁烷在化工利用方面综合效益更高,近些年异丁烷正构化成为了学术界和工业界的关注热点。通过控制Pt负载量和负载位置研究了Pt负载沸石催化剂在异丁烷正构化反应中Pt的作用。结果表明:由于丁烷的异-正转化是吸热反应,反应需要在较高的温度下进行;引入Pt组元可以提高异丁烷转化率,但过多的Pt会促进丁烷裂解生成甲烷和乙烷,降低正丁烷的选择性;质量分数0.10%Pt/HBeta催化剂可以得到良好的催化效果,在反应温度470℃、反应压力2.6 MPa,异丁烷质量空速12 h^(-1)的条件下,正丁烷收率大于39%,对甲烷、乙烷选择性极低。异丁烷正构化反应需要一个适中的金属中心与酸中心的接近度,Pt和酸中心间距离过远会导致裂化副产物增多。 展开更多
关键词 异丁烷 正丁烷 Pt/beta分子筛 双功能催化剂 正构化反应
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