采用小型固定流化床装置(ACE Model C),研究了在反应温度460−540℃下,模型化合物十氢萘在Y分子筛催化剂上的裂化反应路径及生焦机理。结果表明,十氢萘裂化的初始阶段,H+进攻十氢萘上与叔碳原子相连的C−H键和C−C键形成非经典五配位叔正...采用小型固定流化床装置(ACE Model C),研究了在反应温度460−540℃下,模型化合物十氢萘在Y分子筛催化剂上的裂化反应路径及生焦机理。结果表明,十氢萘裂化的初始阶段,H+进攻十氢萘上与叔碳原子相连的C−H键和C−C键形成非经典五配位叔正碳离子是其最主要的引发反应;十氢萘裂化产物主要是丙烯、丙烷、异丁烷、异戊烷、甲基环戊烷、甲苯、二甲基苯等;产物的收率在催化剂上由大到小为,非芳烃、单环芳烃、双环芳烃;十氢萘催化生焦的机理是碳正离子机理,随反应温度和分子筛酸量的升高,双分子氢转移以及脱氢缩合能力增强,焦炭产率和转化率也随之升高。展开更多
采用小型固定流化床(ACE Model C),模型化合物苯乙烯在USY-C、REY-C、ZRP-C、Beta-C催化剂上催化裂化转化规律。结果表明,苯乙烯在分子筛催化剂上的转化率由高到低的顺序是:Beta-C>USY-C>REY-C>ZRP-C,主要发生氢转移反应、烷...采用小型固定流化床(ACE Model C),模型化合物苯乙烯在USY-C、REY-C、ZRP-C、Beta-C催化剂上催化裂化转化规律。结果表明,苯乙烯在分子筛催化剂上的转化率由高到低的顺序是:Beta-C>USY-C>REY-C>ZRP-C,主要发生氢转移反应、烷基侧链裂化反应、烷基转移反应和脱氢缩合反应,其中氢转移是苯乙烯催化裂化过程中最主要的化学反应;Y分子筛催化剂对焦炭和大分子产物的选择性高,ZRP-C和Beta-C催化剂对小分子的裂化气体选择性高。随着反应温度的升高,不利于氢转移反应,苯乙烯的特征产物和转化率随质量空速的升高降低,质量空速对苯乙烯催化裂化反应的影响比反应温度大。展开更多
为了研究双外涵变循环压缩系统的涵道流动匹配规律,发展了涵道流动的计算模型,对压缩系统模式转换过程中外涵道倒流问题的发生机理和影响因素进行了深入分析,总结了压缩系统的倒流判断准则,并基于简化计算模型和全三维计算结果对倒流判...为了研究双外涵变循环压缩系统的涵道流动匹配规律,发展了涵道流动的计算模型,对压缩系统模式转换过程中外涵道倒流问题的发生机理和影响因素进行了深入分析,总结了压缩系统的倒流判断准则,并基于简化计算模型和全三维计算结果对倒流判据进行了验证。研究结果表明,对于一定的压缩系统匹配状态,存在一个决定涵道匹配状态的临界核心机驱动风扇级(Core Driven Fan Stage,CDFS)总压比,当CDFS的实际工作压比高于临界压比时,压缩系统第二外涵道将发生倒流,反之则系统不倒流。复杂涵道系统内的流动损失和堵塞等特性对临界CDFS总压比有显著影响,为了准确判断压缩系统的匹配状态,需要对其进行精确模化。基于简化模型得到的压缩系统倒流临界线可以推广至全三维状态,提出的倒流判断准则具有较高的可靠性和可行性。展开更多
二价汞离子作为一种重要的环境污染物,一直以来受到国内外广泛关注。基于T-T错配的Hg^(2+)检测极大依赖于汞选择性寡聚核苷酸(MSO)的设计,利用SYBR Green I对目前所报道的汞离子探针进行了优化,研究了若干种MSO探针与Hg^(2+)的结合响应...二价汞离子作为一种重要的环境污染物,一直以来受到国内外广泛关注。基于T-T错配的Hg^(2+)检测极大依赖于汞选择性寡聚核苷酸(MSO)的设计,利用SYBR Green I对目前所报道的汞离子探针进行了优化,研究了若干种MSO探针与Hg^(2+)的结合响应,在对探针二级结构进行分析和讨论的基础上,提出最优的富T探针序列,并由此建立了一种基于SYBR Green I的水中汞离子快速、便捷的荧光检测方法。最终测得3种实际水样的加标回收率在82.8%～101.8%之间,相对标准偏差小于15%,表明该方法受环境基质的影响较小,可应用于实际水样中的汞离子检测。展开更多
Potato （Solanum tuberosum L.） is an important staple food and economic crop in many countries. China has led world potato production in recent years. To understand the genetic diversity of potato germplasms and to e...Potato （Solanum tuberosum L.） is an important staple food and economic crop in many countries. China has led world potato production in recent years. To understand the genetic diversity of potato germplasms and to enrich the current gene pool for potato improvement, we made a global collection consisted of 288 potato germplasms from eight countries and the International Potato Center （CIP）. Using SSR and AFLP techniques, we evaluated the genetic diversity and population structure of these 288 potato accessions. A total of 190 alleles on 20 SSR loci were detected and all of the SSR alleles were polymorphic among these potato germplasms with an average of 9.5 alleles per SSR locus ranging from 2 to 23. The effective number of alleles per locus （Ne＊）, Nei＇s genetic diversity （H＊）, and Shannon＇s information index （I＊） was from （0.1709＋0.3698） to （1.6166＋0.3414）, （0.076＋0.1388） to （0.3812＋0.1886）, and （0.1324＋0.1970） to （0.5347＋0.1440）, respec- tively, and the mean polymorphic information content （PIC） value was 0.7312. A total of 988 AFLP alleles were detected by 10 AFLP primer combinations with 983 polymorphic alleles, and 99.49% alleles was polymorphic with an average of 98.3 polymorphic alleles per primer combination ranging from 91 to 116. The values of Ne＊, H＊ and/＊ were from （1.5162＋0.311 ） to （1.6423＋0.3278）, （0.3114＋0.145） to （0.3675＋0.1121）, and （0.4761＋0.1792） to （0.547＋0.1322）, respectively, and the average PIC value was 0.9871. Bayesian analysis discriminated the accessions into seven subgroup and an admix group. The majority of accessions from CIP and China were assigned into SG1, SG5, SG6, SG7 and admix group. Accessions in SG3 were mainly from CIP and two small groups SG2 and SG4 were mainly from northeastern China. In general, the results obtained from Bayesian statistical analysis, cluster analysis and principal coordinate analysis consistently revealed the lack of geographical differentiation among country-wide collections, indicating germplasm introduction was common for the countries out of potato origin center. The poiymorphic markers and the differentiate genetic lineages found in this study provide useful information for potato improvement and conservation programs.展开更多
文摘采用小型固定流化床装置(ACE Model C),研究了在反应温度460−540℃下,模型化合物十氢萘在Y分子筛催化剂上的裂化反应路径及生焦机理。结果表明,十氢萘裂化的初始阶段,H+进攻十氢萘上与叔碳原子相连的C−H键和C−C键形成非经典五配位叔正碳离子是其最主要的引发反应;十氢萘裂化产物主要是丙烯、丙烷、异丁烷、异戊烷、甲基环戊烷、甲苯、二甲基苯等;产物的收率在催化剂上由大到小为,非芳烃、单环芳烃、双环芳烃;十氢萘催化生焦的机理是碳正离子机理,随反应温度和分子筛酸量的升高,双分子氢转移以及脱氢缩合能力增强,焦炭产率和转化率也随之升高。
文摘采用小型固定流化床(ACE Model C),模型化合物苯乙烯在USY-C、REY-C、ZRP-C、Beta-C催化剂上催化裂化转化规律。结果表明,苯乙烯在分子筛催化剂上的转化率由高到低的顺序是:Beta-C>USY-C>REY-C>ZRP-C,主要发生氢转移反应、烷基侧链裂化反应、烷基转移反应和脱氢缩合反应,其中氢转移是苯乙烯催化裂化过程中最主要的化学反应;Y分子筛催化剂对焦炭和大分子产物的选择性高,ZRP-C和Beta-C催化剂对小分子的裂化气体选择性高。随着反应温度的升高,不利于氢转移反应,苯乙烯的特征产物和转化率随质量空速的升高降低,质量空速对苯乙烯催化裂化反应的影响比反应温度大。
文摘为了研究双外涵变循环压缩系统的涵道流动匹配规律,发展了涵道流动的计算模型,对压缩系统模式转换过程中外涵道倒流问题的发生机理和影响因素进行了深入分析,总结了压缩系统的倒流判断准则,并基于简化计算模型和全三维计算结果对倒流判据进行了验证。研究结果表明,对于一定的压缩系统匹配状态,存在一个决定涵道匹配状态的临界核心机驱动风扇级(Core Driven Fan Stage,CDFS)总压比,当CDFS的实际工作压比高于临界压比时,压缩系统第二外涵道将发生倒流,反之则系统不倒流。复杂涵道系统内的流动损失和堵塞等特性对临界CDFS总压比有显著影响,为了准确判断压缩系统的匹配状态,需要对其进行精确模化。基于简化模型得到的压缩系统倒流临界线可以推广至全三维状态,提出的倒流判断准则具有较高的可靠性和可行性。
文摘二价汞离子作为一种重要的环境污染物,一直以来受到国内外广泛关注。基于T-T错配的Hg^(2+)检测极大依赖于汞选择性寡聚核苷酸(MSO)的设计,利用SYBR Green I对目前所报道的汞离子探针进行了优化,研究了若干种MSO探针与Hg^(2+)的结合响应,在对探针二级结构进行分析和讨论的基础上,提出最优的富T探针序列,并由此建立了一种基于SYBR Green I的水中汞离子快速、便捷的荧光检测方法。最终测得3种实际水样的加标回收率在82.8%～101.8%之间,相对标准偏差小于15%,表明该方法受环境基质的影响较小,可应用于实际水样中的汞离子检测。
基金supported by the earmarked fund for China Agriculture Research System(CARS-10)
文摘Potato （Solanum tuberosum L.） is an important staple food and economic crop in many countries. China has led world potato production in recent years. To understand the genetic diversity of potato germplasms and to enrich the current gene pool for potato improvement, we made a global collection consisted of 288 potato germplasms from eight countries and the International Potato Center （CIP）. Using SSR and AFLP techniques, we evaluated the genetic diversity and population structure of these 288 potato accessions. A total of 190 alleles on 20 SSR loci were detected and all of the SSR alleles were polymorphic among these potato germplasms with an average of 9.5 alleles per SSR locus ranging from 2 to 23. The effective number of alleles per locus （Ne＊）, Nei＇s genetic diversity （H＊）, and Shannon＇s information index （I＊） was from （0.1709＋0.3698） to （1.6166＋0.3414）, （0.076＋0.1388） to （0.3812＋0.1886）, and （0.1324＋0.1970） to （0.5347＋0.1440）, respec- tively, and the mean polymorphic information content （PIC） value was 0.7312. A total of 988 AFLP alleles were detected by 10 AFLP primer combinations with 983 polymorphic alleles, and 99.49% alleles was polymorphic with an average of 98.3 polymorphic alleles per primer combination ranging from 91 to 116. The values of Ne＊, H＊ and/＊ were from （1.5162＋0.311 ） to （1.6423＋0.3278）, （0.3114＋0.145） to （0.3675＋0.1121）, and （0.4761＋0.1792） to （0.547＋0.1322）, respectively, and the average PIC value was 0.9871. Bayesian analysis discriminated the accessions into seven subgroup and an admix group. The majority of accessions from CIP and China were assigned into SG1, SG5, SG6, SG7 and admix group. Accessions in SG3 were mainly from CIP and two small groups SG2 and SG4 were mainly from northeastern China. In general, the results obtained from Bayesian statistical analysis, cluster analysis and principal coordinate analysis consistently revealed the lack of geographical differentiation among country-wide collections, indicating germplasm introduction was common for the countries out of potato origin center. The poiymorphic markers and the differentiate genetic lineages found in this study provide useful information for potato improvement and conservation programs.
