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用不对称醚作调节剂合成苯乙烯-异戊二烯-丁二烯橡胶的反应动力学 总被引:1,自引:1,他引:0
以苯乙烯(St)、异戊二烯(Ip)和丁二烯(Bd)为单体,正丁基锂(n-BuLi)为引发荆,乙基乙二醇叔丁基醚(BET)为结构调节剂,合成了线型无规结构的苯乙烯-异戊二烯-丁二烯橡胶(SIBR),进行了聚合反应动力学研究,并与以四氢呋喃(THF)为结构调节剂的体系进行了比较.结果表明,BET的加入提高了聚合反应速率;随反应温度的升高和BET/n-BuLi(摩尔比)的增大,聚合反应速率加快,尤其是St的反应速率提高显著;BET调节聚合速率的能力明显高于THF. 相似文献
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Zhang Liang Bao Zheng Liao Guisheng 《电子科学学刊(英文版)》2000,17(4):289-296
This paper starts with the discussion of the principle of Reduced-Rank (RR) Space-Time Adaptive Processing (STAP). It is followed by a dedication of the upper bound performance of all eigen-based RR methods provided by Cross Spectral Method (CSM) under the condition of a given processor rank and an identical secondary sample size. A performance comparison between two RR STAP processors with prefixed structure and CSM is performed by the means of simulations. It is shown that the performance of time pre-filtering followed by jointly localized STAP structure (i.e. 3DT-SAP) is very close to the upper bound and thereby it is an effective RR approach. 相似文献
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Hui-Min Zhang Fei-Fei Qi Jun Wang Yuan-Yuan Duan Li-Li Zhao Yun-Dan Wang Tong-Cun Zhang Xing-Hua Liao 《International journal of molecular sciences》2022,23(12)
Gastric cancer (GC) is the fifth most common cancer and the third deadliest cancer in the world, and the occurrence and development of GC are influenced by epigenetics. Methyltransferase-like 3 (METTL3) is a prominent RNA n6-adenosine methyltransferase (m6A) that plays an important role in tumor growth by controlling the work of RNA. This study aimed to reveal the biological function and molecular mechanism of METTL3 in GC. The expression level of METTL3 in GC tissues and cells was detected by qPCR, Western blot and immunohistochemistry, and the expression level and prognosis of METTL3 were predicted in public databases. CCK-8, colony formation, transwell and wound healing assays were used to study the effect of METTL3 on GC cell proliferation and migration. In addition, the enrichment effect of METTL3 on DEK mRNA was detected by the RIP experiment, the m6A modification effect of METTL3 on DEK was verified by the MeRIP experiment and the mRNA half-life of DEK when METTL3 was overexpressed was detected. The dot blot assay detects m6A modification at the mRNA level. The effect of METTL3 on cell migration ability in vivo was examined by tail vein injection of luciferase-labeled cells. The experimental results showed that METTL3 was highly expressed in GC tissues and cells, and the high expression of METTL3 was associated with a poor prognosis. In addition, the m6A modification level of mRNA was higher in GC tissues and GC cell lines. Overexpression of METTL3 in MGC80-3 cells and AGS promoted cell proliferation and migration, while the knockdown of METTL3 inhibited cell proliferation and migration. The results of in vitro rescue experiments showed that the knockdown of DEK reversed the promoting effects of METTL3 on cell proliferation and migration. In vivo experiments showed that the knockdown of DEK reversed the increase in lung metastases caused by the overexpression of METTL3 in mice. Mechanistically, the results of the RIP experiment showed that METTL3 could enrich DEK mRNA, and the results of the MePIP and RNA half-life experiments indicated that METTL3 binds to the 3’UTR of DEK, participates in the m6A modification of DEK and promotes the stability of DEK mRNA. Ultimately, we concluded that METTL3 promotes GC cell proliferation and migration by stabilizing DEK mRNA expression. Therefore, METTL3 is a potential biomarker for GC prognosis and a therapeutic target. 相似文献
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Xin-Tong Wei Qi Liao Hao-Ran Zhang Yong-Tu Liang Bo-Hong Wang Ning Xu Meng Yuan 《石油科学(英文版)》2021,(3):994-1010
To investigate highway petrol station replenishment in initiative distribution mode,this paper develops a mixed-integer linear programming(MILP)model with minim... 相似文献