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81.
 研究了伽玛辐照效应对SiGe异质结双极型晶体管的集电极电流和厄尔利电压的影响。经过104 Gy的伽玛总剂量辐照后,集电极电流和厄尔利电压均增加。另外,辐照后发射结和极电结的开启电压和击穿电压也均有一定程度的减小。以上这些变化均是由于辐照产生的缺陷引起发射区和集电区有效掺杂浓度减小所致。  相似文献   
82.
Gu  Jifeng  Chen  Nianzu  Yan  Jingchao  Huang  Taomin  Wang  Donglei  Lai  Yonghua 《Chromatographia》2009,70(11):1709-1713

A sensitive and specific high-performance liquid chromatography–tandem mass spectrometry method has been developed and validated for the determination of clonazepam in rat plasma. Clonazepam and internal standard diazepam were extracted from plasma samples by a single-step protein precipitation. The chromatographic separation was performed on a Dikma ODS-C18 reversed-phase column at 40 °C. The mobile phase composed of a premix of solvent A (0.1% formic acid–4 mM ammonium acetate–water)–solvent B (acetonitrile) (13:87, v/v) at a flow-rate of 0.7 mL min−1. Positive electrospray ionization was utilized as the ionization source. Clonazepam and the internal standard were determined using multiple reaction monitoring of precursor → product ion transitions at m/z 316.0 → 270.0 and m/z 285.1 → 193.2, respectively. The lower limit of quantification was 0.25 ng mL−1 using 50 μL plasma samples and the linear calibration range was from 0.25 to 128 ng mL−1. The within- and between-batch RSDs were lower than 15% and the relative recoveries of clonazepam ranged from 97.4 to 104.7%. The mean extraction recoveries of clonazepam and IS were 79.7 and 77.6%, respectively. The method has been successfully applied to the pharmacokinetic studies in rat after oral administration of clonazepam.

  相似文献   
83.
The asymmetric ring opening reactions of oxabenzonorbornadienes with carboxylic acids are described. By using the complex of [Rh(COD)Cl]2 and (S,S)-BDPP, with ZnI2 as the co-catalyst, a range of aromatic acids and alkyl acids were utilized as nucleophiles to afford the corresponding chiral hydronaphthalene products with high enantioselectivities (84–94% ee). Thus, the present methodology has provides an effective synthetic method for the preparation of enantioenriched hydronaphthalenes.  相似文献   
84.
利用AFS-920双道原子荧光光度计,采用氢化物-原子荧光法测定面粉中的铅含量,通过试验确定了仪器工作参数,载气、屏蔽气流量,介质和掩蔽剂的用量等。该法测定食品中铅含量的相对标准偏差为0.5%(n=11),检出限为0.1ng/mL。铅的浓度在0~40ng/mL与荧光强度呈线性关系,相关系数大于0.999。该法的加标回收率为95.0%~105.0%。  相似文献   
85.
86.
    
Exosomes hold great potential in therapeutic development. However, native exosomes usually induce insufficient effects in vivo and simply act as drug delivery vehicles. Herein, we synthesize responsive exosome nano-bioconjugates for cancer therapy. Azide-modified exosomes derived from M1 macrophages are conjugated with dibenzocyclooctyne-modified antibodies of CD47 and SIRPα (aCD47 and aSIRPα) through pH-sensitive linkers. After systemic administration, the nano-bioconjugates can actively target tumors through the specific recognition between aCD47 and CD47 on the tumor cell surface. In the acidic tumor microenvironment, the benzoic-imine bonds of the nano-bioconjugates are cleaved to release aSIRPα and aCD47 that can, respectively, block SIRPα on macrophages and CD47, leading to abolished “don't eat me” signaling and improved phagocytosis of macrophages. Meanwhile, the native M1 exosomes effectively reprogram the macrophages from pro-tumoral M2 to anti-tumoral M1.  相似文献   
87.
    
Photodynamic therapy (PDT) holds great promise for cancer therapy; however, its efficacy is often compromised by tumor hypoxia. Herein, we report the synthesis of a semiconducting polymer nanoprodrug (SPNpd) that not only efficiently generates singlet oxygen (1O2) under NIR photoirradiation but also specifically activates its chemotherapeutic action in hypoxic tumor microenvironment. SPNpd is self‐assembled from a amphiphilic polymer brush, which comprises a light‐responsive photodynamic backbone grafted with poly(ethylene glycol) and conjugated with a chemodrug through hypoxia‐cleavable linkers. The well‐defined and compact nanostructure of SPNpd (30 nm) enables accumulation in the tumor of living mice. Owing to these features, SPNpd exerts synergistic photodynamic and chemo‐therapy, and effectively inhibits tumor growth in a xenograft tumor mouse model. This study represents the first hypoxia‐activatable phototherapeutic polymeric prodrug system with a high potential for cancer therapy.  相似文献   
88.
    
The facile hydrothermal synthesis of polyethyleneimine (PEI)‐coated iron oxide (Fe3O4) nanoparticles (NPs) doped with Gd(OH)3 (Fe3O4‐Gd(OH)3‐PEI NPs) for dual mode T1‐ and T2‐weighted magnetic resonance (MR) imaging applications is reported. In this approach, Fe3O4‐Gd(OH)3‐PEI NPs are synthesized via a hydrothermal method in the presence of branched PEI and Gd(III) ions. The PEI coating onto the particle surfaces enables further modification of poly(ethylene glycol) (PEG) in order to render the particles with good water dispersibility and improved biocompatibility. The formed Fe3O4‐Gd(OH)3‐PEI‐PEG NPs have a Gd/Fe molar ratio of 0.25:1 and a mean particle size of 14.4 nm and display a relatively high r2 (151.37 × 10?3m ?1 s?1) and r1 (5.63 × 10?3m ?1 s?1) relaxivity, affording their uses as a unique contrast agent for T1‐ and T2‐weighted MR imaging of rat livers after mesenteric vein injection of the particles and the mouse liver after intravenous injection of the particles, respectively. The developed Fe3O4‐Gd(OH)3‐PEI‐PEG NPs may hold great promise to be used as a contrast agent for dual mode T1‐ and T2‐weighted self‐confirmation MR imaging of different biological systems.  相似文献   
89.
Hui  Ailing  Wang  Yuan  Zhu  Kaili  Chen  Jingchao  Fan  Qingping  Zhou  An  Zhang  Wencheng  Wu  Zeyu 《Research on Chemical Intermediates》2017,43(10):5901-5916
Research on Chemical Intermediates - An efficient preparation procedure has been proposed for the synthesis of 5,6-di-O-cinnamyl-l-ascorbic acid ester (5,6-CA–AA) and 2-O-cinnamyl-l-ascorbic...  相似文献   
90.
讨论了具有连续预防接种和脉冲预防接种且具有垂直传染的双线性SIRS传染病模型,分别给出了SIRS传染病模型基本再生数.利用Liapunov函数方法和LaSalle不变原理证明了连续预防接种下无病平衡点和正平衡点的全局稳定性;利用脉冲微分方程的Floquet 乘子理论和比较定理,证明了无病周期解的存在性和全局稳定性.  相似文献   
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