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Search Results: 1 - 10 of 576237 matches for " 李晓歌br>何保荣 "
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一种阵列天线赋形波束综合优化方法

,<br>,
- , 2015,
Abstract: 基于前后向矩阵束研究了阵列天线的方向图赋形问题,提出了一种阵列天线赋形波束综合优化方法.在该方法中,首先确定适当的阵元数目,然后再优化设计激励幅度和阵元位置,最后设计出需要的赋形方向图.在此过程中,先由期望方向图的均匀采样数据构造Hankel-Toeplitz矩阵;然后再对它进行奇异值分解,舍弃不重要的奇异值,得到此矩阵的低秩逼近矩阵;最后基于广义特征值分解求得重构阵列的阵元位置和激励.同时,采用特殊的前后向矩阵来约束极点分布,以保证重构赋形波束方向图的精度可控.仿真实例验证了该方法的快速性和有效性.
Dominant climatic factors of Quercus mongolica geographical distribution and their thresholds
蒙古栎地理分布的主导气候因子及其阈值

YIN Xiaojie,ZHOU Guangsheng,SUI Xinghu,HE Qijin,LI Rongping,<br>殷,周广胜,隋兴华,奇瑾,
生态学报 , 2013,
Abstract: 基于影响植物功能型分布的6个气候变量:年均降水量、气温年较差、最冷月温度、最暖月温度、大于5℃积温和湿润指数,结合蒙古栎地理分布资料,根据最大熵模型和各气候变量对蒙古栎地理分布的贡献,确定了影响蒙古栎地理分布的主导气候因子,即年均降水量、气温年较差、大于5℃积温和最暖月温度;利用模拟的蒙古栎地理分布概率与主导气候因子的关系给出了各主导气候因子的阈值,即年均降水量330—910 mm、气温年较差大于29℃、大于5℃有效积温为1200—3500℃·d、最暖月温度为17—26℃。
Preparation to n-Type B-S Co-Doped Diamond Films with Low Resistivety
低电阻率硼硫共掺杂金刚石薄膜的制备

Hu Xiaojun,Li Rongbin,Shen Hesheng,Dai Yongbing,He Xianchang,<br>胡,,沈荷生,戴永兵,贤昶
半导体学报 , 2004,
Abstract: 利用微波气相沉积方法制备了低电阻率的n型硫掺杂和硼硫共掺杂金刚石薄膜.质子激发X射线荧光测试表明硼硫共掺杂方法能够提高硫在金刚石中的溶解度;扫描电镜和Raman光谱的分析结果表明掺杂金刚石薄膜的晶粒较完整,薄膜中存在较多的非金刚石碳相.Hall效应测试表明薄膜的导电类型为n型,电阻率为0 .0 2 4 6 Ω·cm,载流子浓度为2 .4 0×1 0 1 7cm- 3,Hall迁移率为1 0 3cm2 / (V·s) ;较低的电阻率是薄膜中存在sp2键和掺入的硫杂质等多种因素作用的结果
Study on the Expression, Purification and activity of arginine deiminase
精氨酸脱亚氨酶的表达、纯化和活性研究

ZHANG Xi-dong,<br>张希东,捷雷,张洪义,张宏义,,徐新,肖梅,刘承利,张辉,赵刚
中国生物工程杂志 , 2008,
Abstract: 目的:建立精氨酸脱亚氨酶的高效表达菌种和纯化工艺路线.方法:人工合成编码支原体精氨酸脱亚氨酶(arginine deiminase,ADI)的基因,构建pBV220-ADI原核表达载体,转染大肠杆菌DH5α中并诱导表达目的蛋白,离子交换层析和分子筛层析法纯化目标蛋白.采用体外精氨酸降解试验测定纯化产物活性.结果:成功构建了原核表达载体pBV220-ADI,基因测序正确.转化大肠杆菌DH5α后筛选到高水平表达目的蛋白的菌株,目标蛋白以包涵体形式存在于胞浆内,表达水平超过全菌体蛋白的35%.采用盐酸胍溶解包涵体、低温条件下稀释和透析的方法进行复性.顺次采用阳离子交换和凝胶过滤层析对复性液进行纯化,最终获得纯度达到95%的活性产物.活性测定表明,纯化的ADI比活性为80IU/mg.结论:成功构建了ADI的高效表达菌种,建立了目标物质的分离纯化方法.
一种基于lf-nmr技术的不同含水量猪肉检测方法研究
庞之列,,
食品科学 , 2014,
Abstract: ?研究了一种基于低场核磁共振技术的不同含水量猪肉检测方法。选择猪背部最长肌于宰后5h内注射肉质量分数分别为0%、8.72%、14.23%和17.03%的蒸馏水,于注水后0、12h和24h测定肉色(l*、a*和b*)、低场核磁共振横向弛豫时间(t2)。结果表明,随着注水量的增加,低场核磁共振中t2中第2个峰(t21)的峰时间(t21)增大、峰面积(a21)减小、峰面积比(p21)减小以及色差中的亮度值(l*)增大,其他指标变化相对较小。因此,建议利用t21、a21、p21、l*这4项指标组合,检测不同含水量的猪肉。
The vacancy diffusion near diamond (001) surface by molecular dynamics simulation
空位在金刚石近(001)表面扩散的分子动力学模拟

Hu Xiao-Jun,Dai Yong-Bing,He Xian-Chang,Shen He-Sheng,Li Rong-Bin,<br>胡,戴永兵,贤昶,沈荷生,
物理学报 , 2002,
Abstract: The diffusion process of the vacancy near diamond(001) surface and the effects of temperature on the vacancy diffusion were investigated by molecular dynamics simulation. The results show that when the temperature is about 1000K, the vacancy in the second layer begins to diffuse to the surface. In the 1400_2000K temperature range, the vacancy can migrate to the surface. This result is in a good agreeement with that of experiment and other calculation. In the temperature range of 1400_1800K, two migration stages are observed in the vacancy diffusion process, which correspond to two maximums in the mean square displacement curves. In addition, the vacancy diffusion path was obtained without any constraints exposed on the atoms and the calculated diffusion barrier of the vacancy near diamond(001) surface is about 0^42 eV. We also discussed the effects of vacancy number and different vacancy arrangement on vacancy diffusion at a certain temperature.
Investigation of defect properties in doped diamond films
掺杂金刚石薄膜的缺陷研究

Hu Xiao-Jun,Li Rong-Bin,Shen He-Sheng,He Xian-Chang,Deng Wen,Luo Li-Xiong,<br>胡,,沈荷生,贤昶,邓 文,罗里熊
物理学报 , 2004,
Abstract: The defect properties in chemical vapor deposition diamond films doped by sulfur and boron were investigated by the Doppler broadening measurements and electron paramagnetic resonance (EPR). The results show that the defects annihilating the positrons is almost the same in various doped films, and the interactions between the dopants and the positrons are not distinct. In addition, a small amount of boron atoms can improve the quality of diamond films. The EPR signals of the diamond films arise from carbon dangling bonds.
A molecular dynamics study of energetic particle bombardment on diamond
能量粒子轰击金刚石的计算机模拟

Li Rong-Bin,Dai Yong-Bing,Hu Xiao-Jun,Shen He-Sheng,He Xian-Chang,<br>,戴永兵,,沈荷生,贤昶
物理学报 , 2003,
Abstract: 利用Tersoff势和分子动力学方法研究了初始动能为500 eV的硼粒子注入金刚石的微观行为.结果表明:硼注入后产生温度为5000 K的热峰,其寿命为0.18 ps;同时产生半径为0.45 nm局部非晶化区域,三重配位原子数占该区域原子数的7%.薄膜表层原子向内弛豫,近表层原子向外弛豫,表面层与近表层原子的间距减少了15%,表面层表现为压应力.硼原子以B<110>分裂间隙的形式存在于金刚石结构中.
Hall Measurements, FTIR and EPR for n-Type Boron and Phosphorus Co-doped Diamond Films
硼磷共掺杂n型金刚石薄膜的Hall效应、红外光谱和EPR研究

HU Xiao-Jun,LI Rong-Bin,SHEN He-Sheng,DAI Yong-Bing,HE Xian-Chang,<br>胡,,沈荷生,戴永兵,贤昶
无机材料学报 , 2004,
Abstract: Low resistivity n-type diamond films were prepared by boron and phosphorus co-doping with the ion implantation method. Hall effect measurements show that the samples have nearly equivalent carrier concentration while the Hall mobility and conductivity of B-P co-doped diamond films are higher than those of P doped diamond films. FTIR measurements show that the formation of B-H complexes passivates the acceptor of boron and prevents the phosphorus from passivating by boron. EPR and Raman measurements indicate that the B-P co-doped diamond films have more perfect lattice than those of P doped diamond films, which is benefit to improve the carrier mobility and decrease the resistivity.
SIRT1信号通路介导薯蓣皂苷元在骨性关节炎软骨细胞代谢中的作用机制
Sirtuin type 1 signaling pathway mediates the effect of#br# diosgenin on chondrocyte metabolisms in osteoarthritis

刘军,,甄平,陈慧,周胜虎,田琦,,旭升<br>LIU Jun, HE Xiaole, ZHEN Ping, CHEN Hui, ZHOU Shenghu, TIAN Qi, WANG Rong, LI Xusheng
- , 2017, DOI: 10.11817/j.issn.1672-7347.2017.02.001
Abstract: 目的:在小鼠骨性关节炎(osteoarthritis,OA)模型中观察沉默信息转录调控因子1(sirtuin type 1,SIRT1)信 号通路对软骨细胞代谢的影响以及线粒体抗氧化应激能力的改变,探讨SIRT1信号通路及薯蓣皂苷元(diosgenin,Dgn) 在OA过程中的作用。方法:选择10只C57BL/6小鼠(13.5~18.0 g)建立OA模型,4周后取材,培养软骨细胞并随机分为 4组:OA组、 Dgn+OA组、Dgn+Sirtinol(SIRT1通路阻断剂)+OA组及Sirtinol+OA组。运用Western印迹法检测各组细胞 SIRT1,乙酰化-调节叉头转录因子1(acetylation-regulated transcription factor 1,Ac-FOXO1)和Bax蛋白的表达,同时检测各 组线粒体氧化应激指标琥珀酸脱氢酶(succinate dehydrogenase,SDH)、细胞色素C氧化酶(cytochrome C oxidase,COX)、 超氧化物歧化酶(superoxide dismutase,SOD)水平的改变。结果:与OA组比较,Dgn明显增高SIRT1表达水平(P<0.05), 降低Ac-FOXO1和Bax蛋白表达水平(P<0.05),SDH和COX蛋白表达水平及SOD含量均升高(P<0.05);而与OA+Dgn组相 比,Sirtinol明显降低SIRT1的表达,增高Ac-FOXO1蛋白和Bax蛋白表达水平,降低SDH和COX蛋白表达水平及SOD含 量(P<0.05)。结论:SIRT1信号通路和OA中软骨细胞变化密切相关,Dgn通过激活SIRT1通路,有效减轻OA病理过程 中软骨细胞的线粒体氧化应激损伤,从而发挥抗OA中软骨细胞保护作用
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