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Fast and secure elliptic curve scalar multiplication algorithm based on special addition chains
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作者 刘双根 胡予濮 《Journal of Southeast University(English Edition)》 EI CAS 2008年第1期29-32,共4页
To resist the side chaimel attacks of elliptic curve cryptography, a new fast and secure point multiplication algorithm is proposed. The algorithm is based on a particular kind of addition chains involving only additi... To resist the side chaimel attacks of elliptic curve cryptography, a new fast and secure point multiplication algorithm is proposed. The algorithm is based on a particular kind of addition chains involving only additions, providing a natural protection against side channel attacks. Moreover, the new addition formulae that take into account the specific structure of those chains making point multiplication very efficient are proposed. The point multiplication algorithm only needs 1 719 multiplications for the SAC260 of 160-bit integers. For chains of length from 280 to 260, the proposed method outperforms all the previous methods with a gain of 26% to 31% over double-and add, 16% to22% over NAF, 7% to 13% over4-NAF and 1% to 8% over the present best algorithm--double-base chain. 展开更多
关键词 scalar multiplication algorithm special addition chains side channel attacks double base chain
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Bulk Polymerization of Styrene Using Benzyl Dithiobenzoate as a Chain Transfer
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作者 王艳君 陈文浩 +1 位作者 袁才登 谭欣 《Transactions of Tianjin University》 EI CAS 2004年第1期43-46,共4页
Bulk polymerization of styrene was carried out in the presence of a reversible addition fragmentation chain transfer (RAFT) of benzyl dithiobenzoate (BDB). The comparison between reaction systems with and without BDB ... Bulk polymerization of styrene was carried out in the presence of a reversible addition fragmentation chain transfer (RAFT) of benzyl dithiobenzoate (BDB). The comparison between reaction systems with and without BDB indicates that there is significant retardation in the reaction rate when BDB is used. The molecular weight of styrene polymer prepared with BDB shows linear relationship with the conversion of monomer, polydispersity is as narrow as 1.2, and no gel effects are observed during the polymerization with BDB, which are characteristics of a living radical polymerization. It has been found that the concentrations of BDB and azobis (isobutyronitrile) (AIBN) have opposite effects on the polymerization kinetics, and the AIBN dominates. 展开更多
关键词 reversible addition fragmentation chain transfer (RAFT) benzyl dithiobenzoate (BDB) kinetics STYRENE molecular weight
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R&D补贴对企业技术创新的资源配置效应——国外实证研究进展综述 被引量:1
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作者 刘玉洪 《经济论坛》 2020年第1期24-36,共13页
基于2000年以来国外期刊发表的关于R&D补贴效应的实证研究文献,从内生增长理论和组织学习理论视角,对R&D投入和产出,企业绩效和行为额外性进行评述。研究发现R&D补贴对企业技术创新的资源配置效应因使用不同的数据及指标,... 基于2000年以来国外期刊发表的关于R&D补贴效应的实证研究文献,从内生增长理论和组织学习理论视角,对R&D投入和产出,企业绩效和行为额外性进行评述。研究发现R&D补贴对企业技术创新的资源配置效应因使用不同的数据及指标,不同的研究方法和模型,研究对象的组织、制度、文化等因素的差异而存在异质性,因此,无须追求所谓正确的定论。同时,R&D补贴作为重要的产业政策工具不存在通用模式,必须根据各国的特定环境和制度加以调整。最后,从配置成本、综合框架和政策组合方面对未来的研究方向进行了展望。 展开更多
关键词 R&D补贴 技术创新 资源配置 行为额外性 因果链 政策组合
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Synthesis and characterization of methacrylate matrix resin bearing o-nitrobenzyl group
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作者 郭玲香 管婧 +1 位作者 林保平 杨洪 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第9期3296-3301,共6页
The matrix polymer PTBCHNB bearing o-nitrobenzyl group was successfully synthesized by copolymerization of tertiary-butyl methacrylate(TBMA), cyclohexyl methacrylate(CHMA) and o-nitrobenzyl methacrylate(NBMA) via reve... The matrix polymer PTBCHNB bearing o-nitrobenzyl group was successfully synthesized by copolymerization of tertiary-butyl methacrylate(TBMA), cyclohexyl methacrylate(CHMA) and o-nitrobenzyl methacrylate(NBMA) via reversible addition fragmentation chain transfer(RAFT) polymerization method. PTBCHNB was characterized by FTIR, 1HNMR, GPC and DSC. After UV irradiation, the o-nitrobenzyl groups of PTBCHNB were photocleaved and the resulting carboxyl groups were highly alkali soluble, and PTBCHNB was converted to PCHIBMA bearing carboxyl groups. So, the matrix polymer could be etched by mild alkali solution with no requirements of photoacid generators and other diverse additives. The photocleavable behaviors of PTBCHNB were determined by FTIR, 1H NMR and TGA analysis. The resist formulated with PTBCHNB and cast in THF solution showed square pattern of 10 μm×10 μm using a mercury-xenon lamp in a contact printing mode and tetramethyl-ammonium hydroxide aqueous solution as a developer. 展开更多
关键词 PHOTORESISTS o-nitrobenzyl methacrylate tertiary-butyl methacrylate reversible addition fragmentation chain transfer
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Simulation of Rate Retardation in RAFT Polymerization of Styrene with Low RAFT-Initiator Ratio
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作者 王艳君 岳丽英 +1 位作者 陈文浩 袁才登 《Transactions of Tianjin University》 EI CAS 2005年第2期92-96,共5页
Bulk polymerizations of styrene (St) were carried out in the presence of three reversible addition fragmentation chain transfer (RAFT) agents benzyl dithiobenzoate (BDB), cumyl dithiobenzoate(CDB), and 1-phenylethyl d... Bulk polymerizations of styrene (St) were carried out in the presence of three reversible addition fragmentation chain transfer (RAFT) agents benzyl dithiobenzoate (BDB), cumyl dithiobenzoate(CDB), and 1-phenylethyl dithiobenzoate (PEDB) under low ratio of RAFT agent to initiator. The kinetic model was developed to predict polymerization rate, which indicates that the RAFT polymerization of St is a first-order reaction. In the range of experimental conversions, the plots of -ln(1-x) against time t are approximately linear (x is monomer conversion). The kinetic study reveals the existence of strong rate retardation in RAFT polymerization of styrene. A coefficient K_r is defined to estimate the rate retardation in the RAFT system considering the assumption that the retardation in polymerization rate is mainly attributed to slow fragmentation of the intermediate radicals. K_r relates to the structure of RAFT agents as well as the concentrations of RAFT agent and azobis isobutyronitrile (AIBN). For a certain RAFT agent, the value of K_r is enhanced by the increase in the initial concentration of RAFT agent and the higher ratio of RAFT to AIBN. With the same recipe for different RAFT agents, the increasing trend for the values of K_r is BDB<PEDB<CDB. 展开更多
关键词 reversible addition fragmentation chain transfer (RAFT) polymerization living polymerization STYRENE
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Scholz’s First Conjecture: A Brief Demonstration
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作者 José M. Sautto +3 位作者 Agustín Santiago Carlos N. Bouza Veró nica Campos 《Applied Mathematics》 2016年第1期70-76,共7页
This paper presents a brief demonstration of Schulz’s first conjecture, which sets the upper and lower limits on the length of the shortest chain of addition. Two methods of the upper limit are demonstrated;the secon... This paper presents a brief demonstration of Schulz’s first conjecture, which sets the upper and lower limits on the length of the shortest chain of addition. Two methods of the upper limit are demonstrated;the second one is based on the algorithm of one of the most popular methods for obtaining addition chains of a number, known as the binary method. 展开更多
关键词 addition chain EXPONENTIATION Short chain Scholz’s Conjecture Binary Method
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Aggregation-induced emission polymers via reversible-deactivation radical polymerization Special Collection:Distinguished Australian Researchers
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作者 Nicholas Kai Shiang Teo Bo Fan +1 位作者 Aditya Ardana San H.Thang 《Aggregate》 EI CAS 2024年第1期16-46,共31页
Aggregation-induced emission(AIE)is a unique phenomenon whereby aggregation of molecules induces fluorescence emission as opposed to the more commonly known aggregation-caused quenching(ACQ).AIE has the potential to b... Aggregation-induced emission(AIE)is a unique phenomenon whereby aggregation of molecules induces fluorescence emission as opposed to the more commonly known aggregation-caused quenching(ACQ).AIE has the potential to be utilized in the large-scale production of AIE-active polymeric materials because of their wide range of practical applications such as stimuli-responsive sensors,biological imaging agents,and drug delivery systems.This is evident from the increasing number of publications over the years since AIE was first discovered.In addition,the evergrowing interest in this field has led many researchers around the world to develop new and creative methods in the design of monomers,initiators and crosslinkers,with the goal of broadening the scope and utility of AIE polymers.One of the most promising approaches to the design and synthesis of AIE polymers is the use of the reversible-deactivation radical polymerization(RDRP)techniques,which enabled the production of well-controlled AIE materials that are often difficult to achieve by other methods.In this review,a summary of some recent works that utilize RDRP for AIE polymer design and synthesis is presented,including(i)the design of AIE-related monomers,initiators/crosslinkers;the achievements in preparation of AIE polymers using(ii)reversible addition–fragmentation chain transfer(RAFT)technique;(iii)atom transfer radical polymerization(ATRP)technique;(iv)other techniques such as Cu(0)-RDRP technique and nitroxide-mediated polymerization(NMP)technique;(v)the possible applications of these AIE polymers,and finally(vi)a summary/perspective and the future direction of AIE polymers. 展开更多
关键词 aggregation-induced emission atom transfer radical polymerization nitroxide-mediated polymerization reversible addition–fragmentation chain transfer reversible-deactivation radical polymerization
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Recent Advances of CuAAC Click Reaction in Building Cyclic Polymer 被引量:3
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作者 zhi-hao huang yan-yan zhou +5 位作者 zi-mu wang ying li wei zhang nian-chen zhou 张正彪 朱秀林 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2017年第3期317-341,共25页
Cyclic polymers have attracted more and more attentions in recent years because of their unique topological structures and characteristic properties in both solution and bulk state. There are relatively few reports on... Cyclic polymers have attracted more and more attentions in recent years because of their unique topological structures and characteristic properties in both solution and bulk state. There are relatively few reports on cyclic polymers, partly because of the more demanding synthetic procedures. In recent years, 'click' reaction, especially Cu(I)-catalyzed azide-alkyne cycloaddition(CuAAC), has been widely utilized in the synthesis of cyclic polymer materials because of its high efficiency and low susceptibility to side reactions. In this review, we will focus on three aspects:(1) Constructions of monocyclic polymer using CuAAC 'click' chemistry;(2) Formation of complex cyclic polymer topologies through CuAAC reactions;(3) Using CuAAC 'click' reaction in the precise synthesis of molecularly defined macrocycles. We believe that the CuAAC click reaction is playing an important role in the design and synthesis of functional cyclic polymers. 展开更多
关键词 Cu(I)-catalyzed azide-alkyne cycloaddition(CuAAC) 'Click' chemistry Cyclic polymer Reversible deactivation radical polymerization(RDRP) Atom transfer radical polymerization(ATRP) Reversible addition fragmentation chain transfer polymerization(RAFT)
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Facile synthesis of silicapolymer hybrids via simultaneous RAFT process and hydroxyl-alkoxysilane coupling reaction
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作者 Chunnuan YE Weina QI +3 位作者 Xinhua YU Peipei ZHANG Tengteng HOU Youliang ZHAO 《Frontiers of Chemistry in China》 2011年第3期213-220,共8页
This study aimed at the synthesis of silica particles grafted with better-defined homopolymers and block copolymers by tandem approach.Z-functionalized Sbenzyl S’-(3-trimethoxysilyl)propyltrithiocarbonate(BTPT)was us... This study aimed at the synthesis of silica particles grafted with better-defined homopolymers and block copolymers by tandem approach.Z-functionalized Sbenzyl S’-(3-trimethoxysilyl)propyltrithiocarbonate(BTPT)was used as a couplable RAFT agent to synthesize the target inorganic-organic hybrids.Simultaneous coupling reaction and RAFT process using silica particles and BTPT as raw materials efficiently afforded homopolymers grafted silica,and RAFTsynthesized macro chain transfer agents withω-terminal trimethoxysilane moiety were utilized to mediate graft reaction to prepare silica particles grafted with di-,tri-and tetrablock copolymers comprised of polymer segments such as polystyrene,polyacrylamides and polyacrylates.When the grafted chains had molecular weights ranging between 3920 and 24800 g/mol,the molar grafting ratios,which were dependent on reaction conditions and types and compositions of grafted chains,were estimated to be in the range of 15.2–101μmol/g,and grafted polymers usually had polydispersity indices lower than 1.3,revealing that the grafting process was almost controllable.To the best of our knowledge,this versatile tandem approach is one of the most facile techniques to prepare silica particles grafted with polymeric chains with controlled molecular weight,low polydispersity and precise composition due to its minimal reaction steps,mild conditions,straightforward synthesis and satisfactory controllability. 展开更多
关键词 hybrid material reversible addition fragmentation chain transfer(RAFT) coupling reaction block copolymer surface modification
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