共查询到19条相似文献,搜索用时 468 毫秒
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以可再生资源(如淀粉、纤维素和蛋白质等)为基础发展而来的生物可降解塑料受到人们越来越多的关注,是可降解塑料行业发展的重要方向之一。天然淀粉由于来源广、低成本和可生物降解的特点,广泛用于制备淀粉塑料,并用于农业、食品、医药和包装等行业,有望取代石油基衍生聚合物。淀粉大分子具有结晶结构,所含大量羟基可形成较强的分子间和分子内氢键,使其不能热塑加工,而当加入增塑剂后可破坏其结晶结构,从而用于制备热塑性淀粉。目前,热塑性淀粉的力学性能差,是影响其使用性能的首要问题。近年来国内外开展了大量的研究以试图增强其力学性能。本文主要以不同类型的热塑性淀粉为基础,以淀粉自身改性和外加组分改性两种提高其力学性能的途径为主线,以其力学性能的提升方法和作用机理为重点,系统总结了近年来国内外以提高热塑性淀粉材料的力学性能为目的的研究工作,归纳了影响力学性能的相关因素以及提升途径,并对该领域重点研究的内容进行了总结和展望。 相似文献
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测定了热塑性淀粉(TPS)和热塑性双醛淀粉(TPDAS)在堆肥条件下的生物降解能力。根据ISO 14855建立了一套新的测试体系并且验证了这个体系测定高分子材料生物降解性能的可行性。对热塑性淀粉材料生物降解性的测试结果发现化学改性对于淀粉的降解速率和降解速度都有很大的影响。在可控堆肥条件下TPS比TPDAS降解的要快。TPDAS的降解速度和最终的生物降解百分率和双醛淀粉(DAS)的氧化度有密切的关系。文中讨论了存在这种关系的可能原因。有不同降解速率的TPS和TPDAS的降解过程呈现出三个阶段,即迟滞阶段。降解阶段和平稳阶段。 相似文献
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淀粉和生物降解大分子间的半互穿聚合物网络的耐水性研究 总被引:2,自引:0,他引:2
以淀粉和可生物降解的PCL或PHBV等疏水性脂肪族聚酯为原料, 制备了淀粉基的Semi-IPN材料. 加入PCL或PHBV等疏水性大分子的使淀粉基Semi-IPN材料的耐水性能相对于原淀粉有很大的改善, 通过热处理和溶剂化作用能使Semi-IPN的耐水性进一步提高. 相似文献
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The main chemical approaches to the study of macromolecular structure and dynamics and to the elucidation of interbiopolymer
contact points are considered and illustrated by particular examples. Primary attention is paid to the chemical footprinting
and affinity modification methods. The use of bifunctional reagents for the study of nucleoprotein structure architecture
is described. The ways of enhancing the selectivity of affinity modification available from the literature are analyzed with
an emphasis on catalytically competent (superselective) labeling. The identification of proteins responsible for replication
of the tickborne encephalitis virus by this method is described to demonstrate the possibility of the application of the method
to multicomponent systems such as the nucleus fraction of infected cells.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1225–1231, July, 1999. 相似文献
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Dr. Fa-Jie Chen Dr. Mengmeng Zheng Vincent Nobile Dr. Jianmin Gao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(20):e202200058
This work reports a novel chlorooxime mediated modification of native peptides and proteins under physiologic conditions. This method features fast reaction kinetics (apparent k2=306±4 M−1s−1 for GSH) and exquisite selectivity for cysteine residues. This cysteine conjugation reaction can be carried out with just single-digit micromolar concentrations of the labeling reagent. The conjugates show high stability towards acid, base, and external thiol nucleophiles. A nitrile oxide species generated in situ is likely involved as the key intermediate. Furthermore, a bis-chlorooxime reagent is synthesized to enable facile Cys-Cys stapling in native peptides and proteins. This highly efficient cysteine conjugation and stapling was further implemented on bacteriophage to construct chemically modified phage libraries. 相似文献
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层状复合氢氧化物(LDHs)因其化学组成可调、比表面积大、生物相容性好等特点,目前在环境、能源和生物医药等领域广受关注.然而, LDHs在合成过程中由于其分子内作用力易发生团聚而导致其在基体中的分散不均匀,极大地限制了LDHs在实际中的应用.有机改性是改善LDHs分散性的有效方法,从表面改性和插层改性两个方面综述了近年来LDHs的有机改性方法,并介绍了其在阻燃、吸附、催化、气体阻隔、发光、储能和生物医药材料等领域的应用.最后对改性后LDHs未来的研究方向和应用领域进行了展望. 相似文献
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S. V. Dezhurov I. R. Grin I. V. Safronov G. V. Shishkin O. I. Lavrik S. N. Khodyreva 《Russian Chemical Bulletin》2005,54(5):1311-1321
dUTP and dCTP derivatives containing a 4-azido-2,3,5,6-tetrafluorobenzylideneaminooxy group were incorporated into the 3′-end
of the DNA primer within complexes with the DNA-matrix as analogs of natural dTTP by virtue of catalytic activity of DNA polymerase
β or endogenous DNA polymerases of the cell extract. The photoreactive DNAs synthesized in situ were used for affinity modification of DNA polymerase β and DNA-binding proteins of the cell extract. For the photoreactive
DNA based on these analogs, the efficiency of formation of covalent adducts with DNA polymerase β under the highest degree
of DNA complexation with the enzyme was determined. The yield of covalent DNA adducts with the enzyme was 28–47%, depending
on the type of the analog. The effect of the sequence of the DNA template near the localization of the photoreactive group
on the redistribution of covalent cross-links between the possible targets was demonstrated. A possibility of increasing the
efficiency of DNA polymerase β modification in the presence of a substantial excess of photoreactive DNA using a sensitizer,
a dUTP derivative containing a pyrene residue, was studied. When photoreactive DNA containing a 2,3,5,6-tetrafluoro-4-azidobenzoyl
(FAB) group was used, about 60% of DNA polymerase β was covalently attached to DNA. Photoreactive dNTP analogs ensuring a
high level of protein modification in the cell extract were found.
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Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1273–1283, May, 2005. 相似文献
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Benzotriazolization of 2,4-dihydroxyacetophenone and 2,4-dihydroxybenzophenone has given dibenzotriazolized products: 3,5- [di (2H-benzotriazole-2-yl)]2,4-dihydroxyacetophenone, and 3,5-[di (2H-benzotriazole-2-yl)] 2,4-dihydroxybenzophenone. These compounds are expected to be effective and useful UV absorbers as they both have the 2 (2-hydroxyphenyl)2H-benzotriazole unit and the 2-hydroxybenzophenone (or acetophenone) unit in the molecule. The compounds were characterized by their spectral behavior and particularly by careful study of their UV spectrum. 相似文献