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1.
Zhai  Shidong  Gao  Hui  Luo  Guoqiang  Tao  Junli 《Nonlinear dynamics》2021,106(2):1133-1147
Nonlinear Dynamics - This paper introduces a multigroup COVID-19 model with immunity, in which the total population of each group is partitioned into five compartments, that is, susceptible,...  相似文献   
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Gao  Zhigen  Guo  Jianhua  Ma  Yanyuan 《中国科学 数学(英文版)》2021,64(8):1905-1916
Science China Mathematics - Linear factor models are familiar tools used in many fields. Several pioneering literatures established foundational theoretical results of the quasi-maximum likelihood...  相似文献   
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本文提出了一种应用于光纤延时系统中实现光纤延时精密测量的新方法,用以提高光纤延时测量的精度和准确性.该方法以1064 nm激光调制信号作为光源,通过测量回波信号的幅值和相位信息得到被测通道的频率响应,采用快速傅里叶逆变换得到被测目标的延时信息,实现光纤延时测量.本文通过理论分析和延时测量实验对频域反射法与传统的时域测量方法进行对比,使用频域反射法在调制频率范围10—200 MHz,采样频率间隔0.5 MHz的实验条件下,实现了3.3 ps延时测量分辨率,并证明了该方法具有比时域方法更高的测量精度,测量结果的准确性更好.  相似文献   
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An amorphous cobalt boride alloy with high electronic conductivity is fabricated through the liquid-phase reduction method. Benefiting from large specific surface area and hierarchical pore structure, the as-synthesized Co-B nanoflakes expose substantial electrochemical active sites, promote the transfer of electrons and ions, and accelerate the redox kinetic process. The as-obtained amorphous Co-B alloy sample displays a specific capacitance of 411 F g−1 at 0.5 A g−1, and with the current density increased to 10 A g−1, it maintains 69% of the initial capacitance. The as-assembled asymmetric supercapacitor device reveals electrochemical properties comprising an excellent specific capacitance of 64.3 F g−1 at 0.25 A g−1, superior cyclical stability of 105% after 20,000 cycles at 3 A g−1, and maximum energy density of 22.9 Wh kg−1 at a power density of 200.3 W kg−1. This study demonstrates great potential in developing high-conductivity materials for an asymmetric supercapacitor through utilizing an amorphous cobalt boride alloy as a promising electrode material.  相似文献   
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Cell membrane chromatography is an effective method for screening bioactive components acting on specific receptors in complex systems, which maintains the biological activity of the membrane receptors and improves screening efficiency. However, traditional cell membrane chromatography suffers from poor stability, resulting in a limited life span and low reproducibility, greatly limiting the application of this method. To address this problem, cyanuric chloride-decorated silica gel was used for the covalent immobilization of the cell membranes. Cyanuric chloride reacts with amino groups on the cell membranes and membrane receptors to form covalent bonds. In this way, the cell membranes are not easy to fall off. The column life of the cyanuric chloride-decorated epidermal growth factor receptor/cell membrane chromatography column was extended to more than 8 days, whereas the column life of the normal cell membrane chromatography column dropped sharply in the first 3 days. A cyanuric chloride-decorated epidermal growth factor receptor/cell membrane chromatography online HPLC-IT-TOF-MSn system was applied for screening drug leads from Trifolium pratense L. One potential drug lead, formononetin, which acts on the epidermal growth factor receptor, was screened. Our strategy of covalently immobilizing cell membrane receptors also improved the stability of cell membrane chromatography.  相似文献   
8.
Hu  Duo-Duo  Gao  Qian  Dai  Jing-Cheng  Cui  Ru  Li  Yuan-Bo  Li  Yuan-Ming  Zhou  Xiao-Guo  Bian  Kang-Jie  Wu  Bing-Bing  Zhang  Kai-Fan  Wang  Xi-Sheng  Li  Yan 《中国科学:化学(英文版)》2022,65(4):753-761
Science China Chemistry - A light-induced, nickel-catalyzed three-component arylsulfonation of 1,3-enynes in the absence of photocatalyst is reported. This methodology exhibited mild conditions,...  相似文献   
9.
Chen  Xiulong  Tang  Yuefei  Gao  Shun 《Meccanica》2022,57(1):229-250
Meccanica - The multi-link press mechanism is developing in the direction of high speed and high precision. However, the non-uniform wear of joint clearance seriously affects the output motion...  相似文献   
10.
Pivmecillinam, the ester of biologically active antibiotic mecillinam, is an effective oral preparation to treat urinary tract infections. To study pharmacokinetics in humans, LC-MS/MS methods were developed to quantify pivmecillinam and mecillinam in human plasma, respectively. Considering cephalexin as internal standard, analytes were separated on UltimateXB-C18 columns after protein precipitation by acetonitrile. The mobile phase was composed of water containing 0.1% formic acid and methanol. The multiple reactions monitoring transitions of m/z 440.2→167.1, 326.1→167.1, and 348.1→158.1 were selected to inspect pivmecillinam, mecillinam, and the internal standard in positive ion mode. No apparent matrix effect was perceived. Linearities were obtained over calibration ranges of 0.0500–12.0 and 10.0–15,000 ng/mL, respectively. The intraday precisions were below 5.5%, the interday precisions were below 6.1%, and accuracies were within –8.1 to 13.0%. Stability tests were conducted and an acidification step was explored to enhance the stability of pivmecillinam and mecillinam. Further stability was validated under various storage and processing conditions. Both methods were applied to a pharmacokinetic study of pivmecillinam and mecillinam after oral administration of 400 mg pivmecillinam hydrochloride tablets in healthy Chinese subjects.  相似文献   
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