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调节训练对青少年近视眼高AC/A值的影响 被引量:1
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作者 洪剑威 金梅 《中国当代医药》 2010年第14期168-169,共2页
目的:临床观察调节训练对青少年近视眼高AC/A值的影响。方法:观察2009年1~10月本院眼科门诊8~12岁近视眼并AC/A值>5的患者76例,随机分成治疗组和对照组,各38例;治疗组除验光配镜外每天予调节训练,对照组仅予验光配镜,每月监测各患... 目的:临床观察调节训练对青少年近视眼高AC/A值的影响。方法:观察2009年1~10月本院眼科门诊8~12岁近视眼并AC/A值>5的患者76例,随机分成治疗组和对照组,各38例;治疗组除验光配镜外每天予调节训练,对照组仅予验光配镜,每月监测各患者AC/A值共3次。统计分析两组间AC/A值差异。结果:治疗1个月时,两组AC/A值无明显差异;治疗2、3个月时治疗组的AC/A值小于对照组,差异有统计学意义。结论:调节训练对青少年近视眼高AC/A值有一定的疗效。 展开更多
关键词 调节训练 青少年 近视眼 高ac/A
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基于脉冲宽度调制控制策略的零电流开关高功率因数AC/DC变换器 被引量:12
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作者 贲洪奇 吴新科 刘昭和 《中国电机工程学报》 EI CSCD 北大核心 2003年第9期48-52,共5页
目前,对单级功率因素校正电路的研究大多集中在小功率应用领域,为此该文提出一种能够应用于中大功率场合、实现了零电流开关的单级高功率因数AC/DC变换器拓扑。通过在全桥变换器中增加辅助开关实现了PWM控制,它不仅能够在很宽的负载范... 目前,对单级功率因素校正电路的研究大多集中在小功率应用领域,为此该文提出一种能够应用于中大功率场合、实现了零电流开关的单级高功率因数AC/DC变换器拓扑。通过在全桥变换器中增加辅助开关实现了PWM控制,它不仅能够在很宽的负载范围内实现零电流开关和功率因数校正,而且解决了全桥谐振电路中。在不采用移相控制的情况下,必须采用PFM控制策略的问题。与2级式功率因数校正电路相比,提高了动态响应的速度、降低了成本,并且开关管的电压应力较低。仿真和实验分析验证了变换器的优越性。 展开更多
关键词 功率因数ac/DC变换器 零电流开关 脉冲宽度调制 控制策略
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不同屈光矫正方法治疗高AC/A调节性内斜视的疗效观察 被引量:3
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作者 王雅晨 程璐瑶 +3 位作者 常笛 刘志瀚 张维嘉 傅涛 《眼科》 CAS 2023年第6期488-491,共4页
目的比较双光镜、渐近多焦镜和单光镜对高AC/A调节性内斜视患者立体视觉的恢复效果。设计前瞻性病例系列。研究对象高AC/A调节性内斜视患儿57例,其中配戴渐进多焦镜、双光眼镜、单光眼镜分别为18、23、16例。方法三组患者视远均足矫。... 目的比较双光镜、渐近多焦镜和单光镜对高AC/A调节性内斜视患者立体视觉的恢复效果。设计前瞻性病例系列。研究对象高AC/A调节性内斜视患儿57例,其中配戴渐进多焦镜、双光眼镜、单光眼镜分别为18、23、16例。方法三组患者视远均足矫。渐进多焦点镜片和双光眼镜的下加屈光度为+2.50~+3.00 D,随访3~5年,记录戴镜前后的视远、视近斜视度、AC/A值和近立体视觉的变化并进行统计分析。主要指标看近眼位正位率、AC/A值、近立体视觉。结果三组患者的年龄、性别、屈光状态、治疗前AC/A均无显著差异(P均>0.05),治疗前三组患者近立体视均检测不出。治疗后双光镜、渐近多焦镜和单光镜组患者看近眼位正位率分别为10/23(43%)、10/18(56%)、6/16(38%)无显著差异(χ^(2)=0.71,P=0.70);治疗后三组患儿的近立体视觉均有改善,分别为(6.79±1.67)lnArcsec、(7.43±1.50)lnArcsec、(7.41±1.48)lnArcsec,但三组间差异无统计学意义(F=1.12,P=0.33)。结论单光眼镜与渐进多焦镜和双光眼镜对改善高AC/A调节性内斜视的眼位和近立体视觉有相似的治疗效果。 展开更多
关键词 高ac/A调节性内斜视 渐进多焦镜 双光镜 单光镜
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Correlation Analysis of Characters of Indica Hybrid Rice with High Content of Amylose 被引量:4
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作者 杨扬 况浩池 +4 位作者 曾正明 罗俊涛 陈光珍 何兴材 付均 《Agricultural Science & Technology》 CAS 2013年第3期475-477,共3页
[Objective] The aim was to research and analyze characters and related correlation of indica hybrid rice containing high amylose. [Method] In the research, major characters of 16 species of groups of {ndica hybrid ric... [Objective] The aim was to research and analyze characters and related correlation of indica hybrid rice containing high amylose. [Method] In the research, major characters of 16 species of groups of {ndica hybrid rice and the correlation were explored in rice belts in Sichuan in 2011. [Result] The variation of chalkiness degree was the highest at 26.8%, followed by rate of head rice at 22.89%; varia- tions of head rice rate and chalkiness degree were lower at 0.72% and 2.61%. In addition, rate of unpolished rice was of significantly negative correlation with chalki- ness degree; rate of chalky rice was of extremely positive correlation with chalkiness degree and gel consistency; chalkiness degree was of significantly positive correla- tion with gel consistency; gel consistency was of significantly negative correlation with protein content; amylose content was of insignificant correlation with gel consis- tency (r=0.166 9) of the 16 hybrid groups. These indicated that gel consistency would be still high as the content of amylose grows (AC≥25%). For example, when the content of anylose in Chuanxiang 29A/Luhui 37, Kangfeng AJ6684, and Lefeng A/SR536 exceeded 27%, the gel consistency was over 80 mm in the research. [Conclusion] The research provides references for improvement of amylose content in breeding hybrid rice. 展开更多
关键词 Higher amylose content Indica hybrid rice CHARacTERS Correlaiton analysis
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丙烯醛致大鼠气管和肺损伤中内源性Muc5ac的表达变化
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作者 袁兵 但齐琴 +3 位作者 赵珊 王盛兰 孟步亮 张云辉 《四川大学学报(医学版)》 CAS CSCD 北大核心 2010年第6期994-997,共4页
目的探讨内源性黏蛋白5ac(Muc5ac)在丙烯醛所致大鼠气道损伤中的表达变化及其作用机制。方法用丙烯醛雾化吸入造成大鼠气道黏液高分泌,模拟慢性阻塞性肺疾病。造模后分别用免疫组织化学、Western blot、RT-PCR和原位杂交检测气道Muc5ac... 目的探讨内源性黏蛋白5ac(Muc5ac)在丙烯醛所致大鼠气道损伤中的表达变化及其作用机制。方法用丙烯醛雾化吸入造成大鼠气道黏液高分泌,模拟慢性阻塞性肺疾病。造模后分别用免疫组织化学、Western blot、RT-PCR和原位杂交检测气道Muc5ac的表达变化及定位分布。结果丙烯醛吸入后第1周气道中Muc5ac的基因及蛋白水平均明显上调,并继续上调至第6周达最高水平。Muc5ac表达主要分布于气管、支气管上皮及肺泡上皮细胞中。结论内源性Muc5ac在丙烯醛处理致大鼠气道黏液高分泌中明显增加,提示其在慢性阻塞性肺疾病黏液高分泌发病机制中可能是一个重要分子。 展开更多
关键词 丙烯醛 气道黏液分泌Muc5ac 大鼠
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Effective AC and DC Responses of Nonlinear Composites at Higher Concentration
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作者 LIU Ye LI Zhi 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第1期231-234,共4页
For higher concentration of inclusions, an effective medium approximation (EMA) method is used to investigate the bulk effective response of weakly nonlinear composites, which are subject to the constitutive relatio... For higher concentration of inclusions, an effective medium approximation (EMA) method is used to investigate the bulk effective response of weakly nonlinear composites, which are subject to the constitutive relation of electric displacement and electric field, Dα = εαE +Xα|E|^2 E. As an example of three dimensions, under the external AC and DC electric fields Eapp = Eα(1 + sinωt), we have derived the general effective nonh'near response of composites by the EMA method for higher concentration of spherical inclusions. Furthermore, the effective nonlinear responses at harmonics are predicted. 展开更多
关键词 nonlinear composites effective response ac and DC electric fields
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Purification and Characterization of Angiotensin I Converting Enzyme Inhibition Peptides from Sandworm Sipunculus nudus 被引量:5
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作者 SUN Xueping WANG Man +1 位作者 LIU Buming SUN Zhenliang 《Journal of Ocean University of China》 SCIE CAS CSCD 2017年第5期911-915,共5页
Three angiotensin I converting enzyme(ACE) inhibition peptides were isolated from sandworm Sipunculus nudus protein hydrolysate prepared using protamex. Consecutive purification methods, including size exclusion chrom... Three angiotensin I converting enzyme(ACE) inhibition peptides were isolated from sandworm Sipunculus nudus protein hydrolysate prepared using protamex. Consecutive purification methods, including size exclusion chromatography and reverse-phase high performance liquid chromatography(RP-HPLC), were used to isolate the ACE inhibition peptides. The amino acid sequences of the peptides were identified as Ile-Asn-Asp, Val-Glu-Pro-Gly and Leu-Ala-Asp-Glu-Phe. The IC_(50) values of the purified peptides for ACE inhibition activity were 34.72 μmol L^(-1), 20.55 μmol L^(-1) and 22.77 μmol L^(-1), respectively. These results suggested that S. nudus proteins contain specific peptides that can be released by enzymatic hydrolysis. This study may provide an experimental basis for further systematic research, rational development and clinical utilization of sandworm resources. 展开更多
关键词 hydrolysis converting purification exclusion Angiotensin Inhibition shrimp isolate purified Enzyme
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High Power Density Three-Level Three-Phase AC-DC 48 V Power Supply
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作者 Alessandro Lidozzi Andrea Romanelli Luca Solero 《Journal of Energy and Power Engineering》 2012年第10期1624-1634,共11页
International standards impose several constraints concerning the electric power quality and require that the harmonic content of the line current of grid connected equipment is below assigned limits; for this reason,... International standards impose several constraints concerning the electric power quality and require that the harmonic content of the line current of grid connected equipment is below assigned limits; for this reason, operating of AC-DC converters with high power factor and low line current distortion has become essential. In this paper, the prototypal realization of a three-phase AC-DC 48 V power electronic converter for telecom system supplying is described and experimental testing results are discussed. The main constraints in the power supply design are the required power density of about 900 W per dm3 as well as the absence of the neutral wire in the supply grid. The carried out investigation is focused on three-level power converter configurations which are considered in order to reduce voltage rating of power switches. As a result of the reduced voltage, low on-resistance metal-oxide-semiconductor field effect transistors can be used in the power stage, solution which allows to achieve improved efficiency as well as increased switching frequency with respect to the insulated gate bipolar transistors based two-level topologies. 展开更多
关键词 Power electronics power factor correction three-level converter efficiency.
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广播发射台监控告警系统 被引量:1
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作者 杨怡 《广播与电视技术》 北大核心 2008年第1期77-80,共4页
广播发射台的中心工作就是优质高效地转播好节目,要完成好转播任务,最主要的就是对发射机的调幅度、输出功率和节目信号进行自动控制和监测。我们针对台里发射设备的实际工作情况,设计出相对应的控制电路,仅仅用几百元的投资,就实现了... 广播发射台的中心工作就是优质高效地转播好节目,要完成好转播任务,最主要的就是对发射机的调幅度、输出功率和节目信号进行自动控制和监测。我们针对台里发射设备的实际工作情况,设计出相对应的控制电路,仅仅用几百元的投资,就实现了音频信号的自动/手动切换、报警和对发射机的监控功能。本文介绍该电路的原理及安装、调试要点。 展开更多
关键词 自动切换 精度ac—DC转换 监控
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Targeted inductive heating of nanomagnets by a com- bination of alternating current (AC) and static magnetic fields 被引量:4
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作者 Ming Ma Yu Zhang Xuli Shen Jun Xie Yan Li Ning Gu 《Nano Research》 SCIE EI CAS CSCD 2015年第2期600-610,共11页
The conversion of electromagnetic energy into heat by nanomagnets has the potential to be a powerful, non-invasive technique for cancer therapy by hyperthermia and hyperthermia-based drug release, while temperature co... The conversion of electromagnetic energy into heat by nanomagnets has the potential to be a powerful, non-invasive technique for cancer therapy by hyperthermia and hyperthermia-based drug release, while temperature controllability and targeted heating are challenges to developing applications of such magnetic inductive hyperthermia. This study was designed to control the hyperthermia position and area using a combination of alternating current (AC) and a static magnetic field. MnZn ferrite (MZF) nanoparticles which exhibited excellent hyperthermia properties were first prepared and characterized as an inductive heating mediator. We built model static magnetic fields simply using a pair of permanent magnets and studied the static magnetic field distributions by measurements and numerical simulations. The influence of the transverse static magnetic fields on hyperthermia properties was then investigated on MZF magnetic fluid, gel phantoms and SMMC-7721 cells in vitro. The results showed a static magnetic field can inhibit the temperature rise of MZF nanoparticles in an AC magnetic field. But in the uneven static magnetic field formed by a magnet pair with repelling poles face-to-face, the heating area can be restricted in a central low static field; meanwhile the side effects of hyperthermia can be reduced by a surrounding high static field. As a result we can position the hyperthermia area, protect the non-therapeutic area, and reduce the side effects lust by using a well-designed combination of AC and static field. 展开更多
关键词 HYPERTHERMIA magnetic nanoparticles static magnetic field alternating magnetic field MnZn ferrite
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Numerical analysis of magnetization AC losses in high-temperature superconducting slabs subjected to uniform strains 被引量:5
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作者 XIA Jing ZHOU YouHe 《Science China(Technological Sciences)》 SCIE EI CAS 2014年第4期765-772,共8页
High-temperature superconductors in superconductor apparatuses are subjected to mechanical strains under operating conditions.These strains cause the degradation of the critical current densities and influence AC loss... High-temperature superconductors in superconductor apparatuses are subjected to mechanical strains under operating conditions.These strains cause the degradation of the critical current densities and influence AC losses in the superconductors.Based on the dynamic process of thermomagnetic interaction,we report the results of numerical analysis of AC losses in an infinite high-temperature superconducting slab subjected to a uniform in-plane strain in an alternating external magnetic field parallel to the sample surface.The numerical analysis shows the details of electromagnetic phenomena in the slab and the dependences of AC loss on various external parameters including the uniform strain in the slab and the amplitude and frequency of the external magnetic field.In this paper,we find that whether the magnetic field fully penetrates the superconductor is the key factor that influences the features of AC loss.When the magnetic field cannot fully penetrate the superconductor,the loss rises with increasing strain or decreasing frequency.When the magnetic field can fully penetrate the superconductor,the feature is just opposite.We also analyze the effects of periodic strain on AC loss.It is interesting to find that when the periodic strain frequency equals the external magnetic field frequency,the AC loss reaches the maximum,regardless if the magnetic field fully penetrates the superconductor or not. 展开更多
关键词 high-temperature superconducting slab ac loss strain
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