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141.
Mihail Ionescu Zoran S. Petrović Xianmei Wan 《Journal of Polymers and the Environment》2007,15(4):237-243
Soybean polyols prepared by ring opening reactions of epoxidized soybean oil with hydrogen active compounds (water, alcohols,
organic or inorganic acids, thiols, hydrogen etc.) have a low reactivity in the reaction with isocyanates because the hydroxyl
groups are secondary. This paper presents a simple and convenient method to increase the reactivity of soybean polyols with
secondary hydroxyl groups by ethoxylation reactions with the preservation of triglyceride ester bonds. The method uses mild
reaction conditions: low alkoxylation temperature of 35–45 °C, low pressure of 0.1–0.2 MPa (15–30 p.s.i.) and a superacid
as catalyst (HBF4). The new soybean polyols have a higher reactivity toward isocyanates in polyurethane formation due to the high percentage
of primary hydroxyl groups. The primary hydroxyl content was determined by the second order kinetics of polyol reaction with
phenyl isocyanate. 相似文献
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143.
地裂缝是严重影响我国人类生活、生产建设的主要地质灾害之一,是一种独特的地质灾害,近年来已引起人们的关注,它广泛分布于全国许多地方。框架结构是一种广泛使用的结构形式。由于人类活动或地质构造运动形成地裂缝,进而造成房屋开裂或倾斜。该文针对位于抗震设防区的框架结构房屋,分别用底部剪力法和PKPM静力分析法,来定量研究在地裂缝影响下框架结构的抗震性能,为双重灾害影响下结构抗震鉴定加固提供依据。 相似文献
144.
This research aimed to investigate the interspecific and intraspecific identification of Dendrobium by using the multi-locus method so as to provide a molecular basis for Dendrobium identification through the combination of chloroplast psbA-trnH intergenic region sequences and ribosome 5S rRNA gene spacer sequences. PCR direct sequencing was applied to detect the chloroplast psbA-trnH intergenic region sequences as well as the ribosome 5S rRNA gene spacer sequences of 12 Dendrobium species, while the psbA-trnH intergenic region sequences of Dendrobium denneanum dq-2 variety and dq- 5line were cloned and sequenced for single nucleotide polymorphism (SNP) analyzing. The sequences were analyzed by the software Sequencher4.14, Bioedit7.0, MEGA5.2 and Dansp5.0; the interspecific and intraspecific Kimara-2-Parameter(K2P) distances were also calculated. The phylogenetic tree (using Neighbor joining method) was constructed with Bulbophyllum odoratissimum and Bletilla striata as outgroup. The results showed an average length of chloroplast psbA-trnH gene sequences in Dendrobium as 742.3 bp, with 72 variable sites, including 33 information sites; the average length of the ribosome 5S rRNA gene spacer sequences in Dendrobium was 336.4 bp, with 213 variable sites including 139 information sites. Using psbAtrnH intergenic region sequences in combination with ribosome 5S rRNA gene spacer sequences can not only identify D. denneanum, D. hancockil, D. thysiflorum, D. devonianum, D. moniliforme, D. chrysotoxum, D. officinale, D. heterocarpum and D. nobile, but also differentiate D. officinale from different geographical populations, and distinguish the dq-2 variety and dq 5line with SNP in the multi locus of D. denneanum. 相似文献
145.
Mohd Talib Latif Sofia Aida Ngah Doreena Dominick Intan Suraya Razak Xinxin Guo Thunwadee Srithawirat Idris Mushrifah 《环境科学学报(英文版)》2015,27(7):143-155
The aim of this study was to determine the source apportionment of dust fall around Lake Chini, Malaysia. Samples were collected monthly between December 2012 and March2013 at seven sampling stations located around Lake Chini. The samples were filtered to separate the dissolved and undissolved solids. The ionic compositions(NO-3, SO2-4, Cl-and NH+4) were determined using ion chromatography(IC) while major elements(K, Na, Ca and Mg) and trace metals(Zn, Fe, Al, Ni, Mn, Cr, Pb and Cd) were determined using inductively coupled plasma mass spectrometry(ICP-MS). The results showed that the average concentration of total solids around Lake Chini was 93.49 ± 16.16 mg/(m2·day). SO2-4, Na and Zn dominated the dissolved portion of the dust fall. The enrichment factors(EF) revealed that the source of the trace metals and major elements in the rain water was anthropogenic, except for Fe. Hierarchical agglomerative cluster analysis(HACA) classified the seven monitoring stations and 16 variables into five groups and three groups respectively. A coupled receptor model, principal component analysis multiple linear regression(PCA-MLR), revealed that the sources of dust fall in Lake Chini were dominated by agricultural and biomass burning(42%),followed by the earth's crust(28%), sea spray(16%) and a mixture of soil dust and vehicle emissions(14%). 相似文献
146.
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149.
富油煤原位热解产生的油、气等有机物会通过岩层的压裂缝进入含水层,产生一系列环境行为效应.为探究富油煤热解产物对地下水的影响,以陕北榆神府矿区富油煤与含水介质粉砂为研究对象,采用批量平衡试验,开展了粉砂对煤焦油不同组分的吸附动力学与吸附热力学研究.结果表明:粉砂对煤焦油中酚油、萘油、洗油、蒽油、沥青的动力学吸附均符合准二级动力学方程,等温吸附模型符合Freundlich方程,说明粉砂对5种组分的吸附为单分子层化学吸附;受富油煤热解焦油组分含量差异影响,粉砂对5种组分的吸附量表现为酚油<萘油<洗油<蒽油<沥青,其最大吸附量分别为0.4520、0.7926、1.9015、3.6336、11.8001 mg·g-1,吸附量总和占煤焦油含量的68%~85%;随着温度的升高,粉砂对5种组分的吸附能力均有所减弱,表明升高温度不利于吸附行为的进行,且反应的ΔG0<0表明粉砂对5种组分的吸附过程主要以化学吸附为主且属于放热反应. 相似文献
150.
目的 解决大气环境试验站的气象数据报表存在数据缺失、数据超过边界、数据内部不一致、数据时间不一致等问题,采用数据质量审核技术找出缺失、可疑或错误的数据,对科研人员进行警示,使其能够追根溯源,分析存在问题的原因。方法 参照相关规程和标准,建立环境因素数据质量审核算法和审核流程,并使用计算机语言编程固化流程和算法,利用多线程算法对数据进行扫描,实现大批量气象数据的并行审核。结果 利用Python语言设计了环境因素质量控制软件,通过该软件的应用证明了该方法合理、有效,能够快速、准确地标注气象数据报表中存在质量问题的数据。利用软件统计了存在问题数据的数量和正确率。结论 通过加载数据测试,证明了环境因素数据质量审核方法和审核流程合理有效,利用设计的审核软件实现了气象数据报表快速审核,提高了审核效率,减少了科研人员的劳动强度,为进一步填补、修正和利用数据奠定了基础。 相似文献