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排序方式: 共有118条查询结果,搜索用时 15 毫秒
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SiC/Fe界面固相反应模型 总被引:7,自引:0,他引:7
使用XRD、EPMA和SEM等研究了SiC/Fe界面固相反应产物的相组成、反应区的显微结构以及反应区中反应物原子的浓度分布。SiC/Fe界面固相反应形成Fe3Si、Fe(Si)和石墨态C沉积物,Fe3Si的形成为该反应提供了足够的热力学驱动力。1100°×3h热处理后,反应区由调整的C沉积物区/均匀的C沉积物区/无C沉积物区(从SiC侧至Fe侧)构成。建立SiC/Fe界面固相反应模型以解释SiC/Fe界面固相反应的微观机理。在SiC/Fe界面固相反应过程中,SiC分解是不连续的,从而在SiC界面前沿形成调整的C沉积物区独特结构。 相似文献
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基于社交媒体大数据的交通感知分析系统 总被引:2,自引:0,他引:2
社交媒体数据中蕴含了丰富的交通状态信息,这些信息以人类语言为载体,包含了大量对交通状态的因果分析与多角度描述,可以为传统交通信息采集手段提供有力补充,近年来已成为交通状态感知的重要信息来源.本文以新浪微博为主要数据来源,分别利用支持向量机算法、条件随机场算法以及事件提取模型完成微博的分类、命名实体识别与交通事件提取,开发了基于社交媒体大数据的交通感知分析与可视化系统,可以为交通管理部门及时提供交通舆情及突发交通事件的态势、影响范围、起因等信息.在交通信息采集系统建设较为薄弱的地区,本文建立的系统可以为交通管理提供信息补充. 相似文献
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The three-particle deterministic secure and high bit-rate direct quantum communication protocol and its improved version are analyzed. It shows that an eavesdropper can steal the sender’s secret message by the intercept-resend attack and the entanglement attack. The original version is even fragile under denial-of-service attack. As a result, some suggestions to revise them are given. 相似文献
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Zhu L Verma R Roccatano D Ni Y Sun ZH Schwaneberg U 《Chembiochem : a European journal of chemical biology》2010,11(16):2294-2301
Arginine deiminase (ADI, EC 3.5.3.6) is a potential antitumor drug for the treatment of arginine‐auxotrophic tumors such as hepatocellular carcinomas (HCCs) and melanomas, and studies on human lymphatic leukemia cell lines have confirmed that ADI has antiangiogenic activity. Recent studies showed that a combination of taxane and ADI‐PEG20, which induces caspase‐independent apoptosis, is more effective than taxane monotherapy for prostate cancer. The main limitation of ADI from Pseudomonas plecoglossicida (PpADI) and of many other ADI enzymes lies in their pH‐dependent activity profile. PpADI has a pH optimum at 6.5 and a pH shift from 6.5 to 7.5 results in an ~80 % activity drop (the pH of human plasma is 7.35 to 7.45). In 2010, we reported a proof of concept for ADI engineering by directed evolution that resulted in variant M2 (K5T/D44E/H404R). M2 has a pH optimum of pH 7.0, a fourfold higher kcat value than the wild‐type PpADI (pH 7.4, 0.5 M phosphate buffer), and an increased Km value for substrate arginine. In our latest work, variants M5 (K5T/D38H/D44E/A128T/H404R) and M6 (K5T/D38H/D44E/A128T/E296K/H404R) were generated by directed evolution by employing PBS buffer (pH 7.4), which mimics physiological conditions. The S0.5 value of parent M3 (K5T/D44E/A128T/H404R) decreased from 2.01 to 1.48 mM (M5) and 0.81 mM (M6). The S0.5 value of M6 (0.81 mM ) is lower than that of wild‐type PpADI (1.30 mM ); the kcat values improved from 0.18 s?1 (wild‐type PpADI) to 17.56 s?1 (M5, 97.6‐fold) and 11.64 s?1 (M6, 64.7‐fold). 相似文献
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Zhi-Hao Wang Wanting Huang Shuhao Zhang Mengyu Chu Na Yin Chaoran Zhu Zhenzhong Zhang Jinjin Shi Junjie Liu 《Advanced functional materials》2023,33(17):2212013
Colorectal cancer (CRC) is the second most common cause of cancer incidence worldwide. Oral drug delivery systems (ODDS) have shown great promise for CRC therapy, but the delivery efficiency is still challenged by the dense intestinal mucus barrier and nonspecific interception of abnormally proliferated pathogenic bacteria. Herein, self-thermophoretic nanoparticles (CTPB) is presented to enhance intestinal mucus penetration and reduce pathogenic bacteria interception in CRC for efficient drug delivery. The nanoplatform introduces hollow mesoporous copper sulfide and is asymmetrically sprayed with titanium dioxide as the self-thermophoretic matrix. Based on the close relationship between pathogenic bacteria and CRC, the nanoplatform is camouflaged by the biomimetic membrane of Staphylococcus aureus to precisely anchor in the intestinal segment of CRC. After near-infrared laser irradiation, CTPB can effectively increase the intestinal mucus penetration efficiency by 2.7 folds, and decrease the pathogenic bacterial interception by 3.5 folds via the self-thermophoretic propulsion force. In orthotopic CRC-bearing mice, CTPB vastly improved the drug delivery efficiency to CRC after oral administration, thus showing a 99.4% antitumor rate after three weeks of treatment, which provides new insight into oral drug delivery for CRC therapy. 相似文献
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Zhi-Hao Liu Han-Wu Chen Juan Xu Wen-Jie Liu Zhi-Qiang Li 《Quantum Information Processing》2012,11(6):1785-1795
A deterministic multiparty quantum secret sharing scheme is put forward, in which Bell states in high-dimensional Hilbert space are used. Only by preforming High-dimensional Bell measurements, all agents can recover the secret according to the dealer??s announcement when collaborating with each other. It shows that unitary operation for encoding deterministic secret is unnecessary in quantum communication. The security of the transmission of the high-dimensional Bell states can be ensured by randomly using one of the two mutually unbiased bases for eavesdropping checking, and thus by which the proposed quantum secret sharing scheme is secure against usual attacks. In addition, the proposed scheme has three advantages: generality, high resource capacity and high security. 相似文献
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本文用变分法和快速傅里叶变换,分析了在块状均匀与非均匀材料中传输的强超快脉冲的光谱分布,修正了Manassah的错误结果。 相似文献