145 resultados para 5-methoxy-3,4-dehydroxanthomegnin
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We report a heteroleptic ruthenium complex (007) featuring the electron-rich 5-octyl-2,2'-bis(3,4-ethylenedioxythiophene) moiety conjugated with 2,2-bipyridine and exhibiting 10.7% power conversion efficiency measured at the AM1.5G conditions, thanks to the enhanced light-harvesting that is closely related to photocurrent. This C107 sensitizer has an extremely high molar extinction coefficient,of 27.4 x 10(3) M-1 cm(-1) at 559 nm in comparison to its analogue C103 (20.5 x 10(3) M-1 cm(-1) at 550 nm) or Z907 (12.2 x 10(3) M(-1)cm(-1) at 521 nm) with the corresponding 5-hexyl-3,4-ethylenedioxythiopliene- or nonyl-substituted bipyridyl unit. The augmentation of molar extinction coefficients and the bathochromic shift of low-energy absorption peaks along with the pi-conjugation extension are detailed by TD-DFT calculations. The absorptivity of mesoporous titania films grafted with Z907, C103, or C107 sublinearly increases with the molar extinction coefficient of sensitizers, which is consistent with the finding derived from the surface coverage measurements that the packing density of those sensitizers decreases with the geometric enlargement of ancillary ligands.
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A new polymer-supported metallocene catalyst has been prepared, The polymer-supported metallocene displayed considerably high activity in ethylene polymerization, the highest being 3.62x10(7) gPE/molZr.h, the molecular weight of the polyethylene produced was Mn = 1.29x10(5). about 3-4 times those of corresponding homogeneous zirconocenes. The polymer-supported metallocene keeps the characteristics of homogeneous metallocene catalysts, and offers some features, such as adaptable to gas phase and slurry processes: easy to prepare in low cost: relatively high activity and lower MAO/Zr ratio; lower inorganic residues in the polyolefins as compared to cases of SiO2, Al2O3 or MgCl2; unitary active structure, no complex surface as with SiO2; good control of morphology of the resulting polymer.
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对γ辐照新型聚芳醚酮(PEK-C)的介电行为进行研究。20—200℃范围内的介电温度谱和30Hz—1MHz的频率谱表明。经过2.02 MGy剂量辐照后,PEK-C的介电行为发生了明显变化,不仅谱图形状有了改变,而且因辐照的PEK-C结构中产生了稳定的三苯自由基,介电系数ε′和介电损耗因子ε″大幅度增加,在20℃,1kHz时前者由3上升到5,后者由5.4×10~(-3)上升到4.6×10~(-1)。
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Four new highly brominated and fully substituted mono- and bis-phenols, 1-(2,3,6-tribromo-4,5-dihydroxybenzyl)pyrrolidin-2-one (1), 1,2-bis(2,3,6-tribromo-4,5-dihydroxyphenyl)ethane (2), 6-(2,3,6-tribromo-4,5-dihydroxybenzyl)-2,5-dibromo-3,4-dihydroxybenzyl methyl ether (3), and 2,3,6-tribromo-4,5-dihydroxybenzyl methyl sulfone (4), were characterized from the marine red alga Symphyocladia latiuscula. In addition, five known bromophenols, bis(2,3,6-tribromo-4,5-dihydroxyphenyl)methane (5), bis(2,3,6-tribromo-4,5-dihydroxybenzyl) ether (6), 2,3,6-tribromo-4,5-dihydroxybenzyl methyl ether (7), 2,3,6-tribromo-4,5-dihydroxymethylbenzene (8), and 2,3,6-tribromo-4,5-dihydroxybenzaldehyde (9), were also isolated and identified. The structures of these compounds were elucidated by spectroscopic methods including 1D and 2D NMR as well as by low- and high-resolution mass spectrometric analysis. Structurally, all of these compounds are highly brominated and fully substituted, and contain one or two 2,3,6-tribromo-4,5-dihydroxyphenyl unit(s) in each of the molecules. In addition, compound 4 possesses a unique sulfone structural feature. Each of the isolated compounds was evaluated for alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical-scavenging activity and all were found to be potent, with IC50 values ranging from 8.1 to 24.7 mu M, compared to the known positive control butylated hydroxytoluene (BHT), with an IC50 of 81.8 mu M.
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海藻是海洋生物中的一大类群,由于其特殊的生活环境,能够代谢产生大量结构独特多变和活性特殊多样的代谢产物,是化学和生物活性多样性研究的重要对象之一。我国海域辽阔,海藻资源丰富,为寻找结构新颖、生理活性独特的先导化合物,加强对海藻资源的开发利用,本论文对中国沿海的三种海洋红藻进行了化学成分和生物活性研究,同时对山东青岛海域生物量丰富的一种海洋红藻松节藻进行了动物体内抗糖尿病活性研究。 利用正相硅胶柱色谱、Sephadex LH-20柱色谱以及反相HPLC和重结晶等现代分离手段,对山东青岛沿海的红藻扇形叉枝藻(Gymnogongrus flabelliformis)进行了系统的化学成分研究,从中得到单体化合物26个,通过波谱学方法(IR、MS、NMR等)鉴定了他们的结构,分别为(3R,6R,7E)-(+)-3-O-phenylacetyl- 4,7-megastigmadiene-9-one(1),(3R,7E)-(-)-3-O-phenylacetyl-5,7-megastigmadiene -9-one(2),(3S,6R,7E)-(+)-3-hydroxyl-4,7-megastigmadien-9-one(3),(3S,5R,6S,7E)- (-)-3-hydroxy-5,6-epoxy-7-megastigmene-9-one(4),(3S,5S,6R,7E)-(+)-3-hydroxy- 5,6-epoxy-7-megastigmene-9-one(5),Dehydrovomifoliol(6),(3R)-(-)-4-[(2R,4S)-4- acetoxy-2-hydroxy-2,6,6-trimethylcyclohexylidene]-3-buten-2-one(7),2,3,3′-三溴-4,4′,5,5′-四羟基-1′-乙氧甲基双苯基甲烷(8),2,2′,3,3′-四溴-4,4′,5,5′-四羟基双苯基甲烷(9),3-溴-4,5-二羟基苯甲醛(10),2,3-二溴-4,5-二羟基苯甲基甲醚(11),2,3-二溴-4,5-二羟基苯甲醇(12),N, N-二甲基酪胺(13),4-羟基苯甲酸乙酯(14),4-羟基苯甲基乙醚(15),4-羟基苯乙基乙酯(16),4-羟基苯乙酸甲酯(17),4-羟基苯甲醛(18),豆甾-4-烯-3-酮(19),胆甾-4-烯-3-酮(20),胆甾醇(21),尿嘧啶(22),尿嘧啶核苷(23),腺嘌呤核苷(24),丁二酸(25),5-羟基-4-甲基-5-戊基-2,5-二氢呋喃-2-酮(26)。其中化合物1、2为新化合物,化合物3为新天然产物,所有化合物均为首次从该属海藻中分离得到。通过 MTT 法对部分单体化合物进行了肿瘤细胞毒活性筛选, 结果表明,化合物8、9、10、12对筛选的所有细胞株均有较强细胞毒活性,化合物11对人肺癌细胞株(A549)、人肝癌细胞株(Bel 7402)、人结肠癌细胞株(HCT-8)有一定细胞毒活性。通过研究单体化合物对小鼠腹腔巨噬细胞TNF-分泌的影响,对其进行抗炎活性筛选,结果表明,化合物8、9、11、13、17、23、24、25对小鼠腹腔巨噬细胞TNF-分泌表现出明显的抑制作用。 从采自山东荣成镆铘岛的红藻小珊瑚藻(Corallina pilulifera)的乙酸乙酯萃取物中分离得到16个单体化合物,通过波谱学方法鉴定化合物结构14个(另外2个正在鉴定中),分别为2α-乙氧酰基-2β-羟基-A-降胆甾-5-烯-4-酮(27),胆甾-4-烯-3-酮(28),胆甾醇(29),3β-羟基-胆甾-5,24(28)-二烯-7-酮(30),2α-羟基-胆甾-4-烯-3-酮(31),6α-羟基-胆甾-4-烯-3-酮(32),3β-羟基-胆甾-5-烯-7-酮(33),(E)-phytol epoxide(34),Phytenal(35),3,7,11,15- tetramethyl-hexadec-2-en-1-oll(Phytol)(36),Loloilide(37),(3S,5R,6S,7E)-(-)-3-hydroxy-5,6-epoxy-7- megastigmene-9-one(38),Dehydrovomifoliol(39),4-羟基苯甲醛(40)。其中,化合物 31为新天然产物,化合物27为首次从植物中分离得到,所有化合物均为首次从该种海藻中分离得到。通过 MTT 法对分离得到的单体化合物进行了肿瘤细胞毒活性筛选,化合物27和化合物32对筛选的所有肿瘤细胞株均有细胞毒活性,且化合物27对人胃癌细胞株(BGC-823)、人结肠癌细胞株(HCT-8)和人卵巢癌细胞株(A2780)具有中等强度抑制活性。化合物28、化合物31和化合物33对人肝癌细胞株(Bel 7402)、人结肠癌细胞株(HCT-8)和人卵巢癌细胞株(A2780)有一定细胞毒活性。 从采自广西北海涠洲岛的多管藻Polysiphonia sp.的乙酸乙酯萃取物中分离得到6个单体化合物,通过波谱学方法鉴定化合物结构5个(另外1个仍在鉴定),分别为胆甾醇(41),3,7,11,15-tetramethyl-hexadec-2-en-1-ol(Phytol)(42),3-吲哚甲醛(43),4-羟基苯甲醛(44),4-羟基苯甲酸(45)。 对山东青岛沿海的松节藻 (Rhodomela confervoides) 乙醇提取物进行了初步的体内抗糖尿病活性研究,采用链脲佐菌素诱导的2型糖尿病(STZ-DM)大鼠模型对其进行体内降糖实验,结果发现,松节藻乙醇提取物在糖尿病大鼠体内不仅具有显著的降血糖作用,且呈现良好的量–效关系,而且能够纠正糖尿病引发的物质代谢紊乱,增加体重,提高试验动物的成活率,因此具有良好的应用开发前景。
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黑碳和多环芳烃都是燃烧产生的污染物,并广泛存在于土壤及海洋特别是近海沉积物中。由于黑碳和多环芳烃对环境及生态系统具有不同的影响途径和危害,多年来一直受到环境研究者的极大重视。本文对我国近海几个海区(渤海湾、北黄海、胶州湾、南海珠江口及其邻近海区)沉积物中黑碳和多环芳烃的含量、分布及来源进行了研究,并首次对各海区表层沉积物中黑碳和多环芳烃的相关性进行了分析。 数据显示,中国近海各海区(渤海湾、北黄海、胶州湾、南海珠江口及其邻近海区)表层沉积物中黑碳的浓度范围为0.1 - 2.45 mg/gdw,占总有机碳浓度的1 - 41%,具有较大的空间差异。渤海湾表层沉积物中黑碳浓度最高(平均为2.18 mg/gdw),占沉积物中总有机碳浓度的27 - 41%。相比之下,北黄海、胶州湾和南海珠江口及其邻近海区表层沉积物中黑碳浓度较低,分别占沉积物中总有机碳浓度的6%、8%和5%。黑碳的分布主要受其来源的影响,陆地来源和河流输入是中国近岸海区表层沉积物中黑碳的重要来源。该研究显示黑碳在沉积物中的埋藏可能代表我国近海各海区碳循环中的一个重要碳汇。 中国近海各海区(渤海湾、北黄海、南海珠江口及其邻近海区)表层沉积物中多环芳烃的浓度范围为47.5 – 3673.5 ng/g(均为干重),亦具有很大的空间差异。渤海湾中多环芳烃的浓度最高(82.9 – 3673.5 ng/g),反映了该地区受人类污染严重的特征。在三个海区表层沉积物中,单组分多环芳烃的分布也具有明显不同的特征,渤海湾主要以5、6环的多环芳烃为主,而北黄海和南海珠江口及其邻近海区3、4环多环芳烃的浓度较高。基于多环芳烃的单组分分布特征和一些特殊指数,可以得到渤海湾表层沉积物中的多环芳烃以木材、煤的不完全燃烧来源为主,而北黄海海区和南海珠江口及其邻近海区的多环芳烃显示出木材、煤的燃烧和石油燃烧的混合来源。 中国近海表层沉积物中黑碳浓度与多环芳烃的浓度并不存在很好的相关性,这说明中国近海表层沉积物中的黑碳和多环芳烃具有不同的来源,且在沉积物中的埋藏受控于不同的地球化学作用。
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报道了青海赖草属植物一新种:圆稃赖草(Leymus oblongolenmatus L.Zhi et L.B.Cai)。该种的主要特征如下:多年生草本,杆直立、光滑、疏丛,高60~90cm。叶鞘粗糙,边缘膜质,长于或短于节间,叶舌膜质;叶片边缘内卷。穗状花序直立、密集、黄绿色,长10~15cm,宽5~15mm,穗轴粗糙,小穗常3~4枚生于每节,含3~6小花;颖披针形,长4~7mm,具3~5脉,边缘膜质;外稃长圆状披针形,不明显3脉,背部疏生短柔毛;花药黄色,长4~5mm。该种与L.paboahus相似。
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In this study, 260 mollusk fossil samples from a Red Clay sequence at Xifeng, Gansu province, in the northern China were analyzed quantitatively. 12 fossil species and four fossil zones have been identified. Three main ecological groups were determined based on ecological requirement of each mollusk taxon. According to fossil composition and succession of three ecological groups, the author discussed the origin and sedimentary environment of the red clay deposits, and the process of ecological environmental changes as well as the variations of the East Asia monsoons during 6.2-2.4 Ma in the Loess Plateau. A preliminary study on periodicity of paleoclimatic changes was also conducted by using spectral analysis method. The main results and conclusions are presented as follows:A continuous land mollusk fossil sequence of 6.2-2.4 Ma from Xifeng Red Clay Formation has been established, which provided a basic data for studying the environmental changes during late Miocene to Pliocene.The study of composition and preservation condition of mollusk fossils reveals a terrestrial in situ ecological population in the Red Clay Formation. All of identifiable mollusk species are composed of terrestrial taxa, which support the view that the Red Clay is an eolian origin, similar to the overlying Quaternary loess deposits.The mollusk record reveals the processes of ecological and environmental changes during 6.2-2.4 Ma in the Loess Plateau. Climatic changes experienced cold and dry from 6.2-5.4 Ma, warm and wet during 5.4-4.5 Ma, mild and moderate from 4.5-3-4 Ma, to rapid cooling and drying after 3.4 Ma. From '5.4- 2.4 Ma, climate was stepwise cooling. The cooling trend is in good agreement with a general1 0global cooling trend during this period, as documented by marine 5 0 records.4. Three remarked ecological shifts took place in mollusk assemblages from 6.2-2.4 Ma, focused on about 5.4, 4.5 and 3.4 Ma. The warming shift around 5.4 Ma was probably related to the rising of the global temperature. The cooling shifts around 4,5 and 3.4 Ma however might be closely linked to the uplift of Tibet Plateau and the development of Northern Hemisphere ice sheet.The succession in mollusk ecological groups also recorded the variability of the East Asian winter and summer monsoon. The winter monsoon dominated two periods from 6.2-5.4 Ma and from 3.4-2.4 Ma, while the summer monsoon was strong during 5.4-4.5 Ma. The variations in winter and summer monsoons were in phase during 4.5-3.4 Ma. Monsoon regimes changed with the duration about 1 Ma, which roughly corresponds to the cycle driven by tectonic activity on the time scales of ICP-IO7 years. In addition, mollusk fossils recorded the large amplitude and high frequency fluctuations overlapped on 105-107 years climate cycle.The maximum entropy spectral analysis and filter-band analysis of total mollusk individuals and three typical ecological groups suggest that the climate changes controlled mainly by solar insolation had periods about 70 ka and 40 ka on the time scales of 105 during late Miocene-Pliocene. Climatic periodicity intensified from 4.0 Ma, which reflected strengthened forcing by high latitude ice volume.
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本文以油气地质学、有机地球化学等学科的理论为指导,综合利用地质、地球化学、地球物理、分析测试等资料,结合盆地分析,充分运用油气成藏动力学和流体封存箱等新理论,运用含油气系统分析方法,对东营凹陷西南部博兴地区含油气系统的静态要素和动态过程进行了综合研究。首次在含油气系统内进行了油气成藏系统的划分和评价,建立了油气藏形成的地质概念模式,探讨了油气成藏机理,系统总结了油气富集规律及其控制因素,指出了进一步勘探的方向。主要取得了以下成果和认识:(1)通过盆地沉积充填综合研究,将博兴地区第三系划分出5个层序,提出馆陶组与下伏地层间、孔店组与下伏中生界地层间区域性不整合面,是区内油气聚集成藏的有利部位。提出地层的发育明显受构造控制,高青断层和石村断层控制了博兴注陷的构造一沉积演化、地层格架和沉积体系的空间展布,进而对烃源岩、储集层的发育、油气的运移和聚集具有明显的制约作用。(2)运用含油气系统分析方法,对博兴地区的成藏静态地质要素和动态作用进行了深入研究。指出研究区油气成藏条件优越,沙四上、沙三段是主要烃源岩,区内发现的石油可分为沙三型、沙四型和混合型;系统内各类储层发育,沙三段、沙一段和馆陶组构成了三套区域性盖层,生储盖具有三种不同的配置关系。晚第三纪馆陶期一明化镇期是生、排烃和油气运聚高峰期。(3)系统总结了研究区的油气藏类型及特征,探讨了它们在空间上的展布规律。纯化、小营、正理庄等地区以构造油气藏为主,高青断裂带、金家斜坡带以地层和构造一地层复合油气藏为主,梁家楼、乔庄、大芦湖等地区以构造一岩性、粉胜油气藏为主。构造汾由气藏分布于各层系,沙一段以构造一岩性、岩性油气藏为主,东营组、中生界以地层和构造一地层复合油气藏为主。(4)首次提出了在含油气系统内进一步划分油气成藏系统的新方案,明了壳了成藏系统的内涵,提出成藏系统是相对独立的油气运聚单元,润明了成藏系统的划分原则和方法。将研究区划分为西部高青断裂带、中部金家一正f甲川樊家、东部纯化-梁家楼和!北部小营平方匕等4个油气成藏系统,并对各系统进行了分析和评价。进步划分出8个成藏子系统,揭示了构造背景对各子系统们油气藏形成的控制作用。(5)根据地层压力与油气藏形成特征,提出了两种成藏动力学机制:自源封闭成藏动力学机制和它源开放成藏动力学机制。利用流体封存箱理论解释了本区油气运移聚集的机理模式,提出研究区油气藏的形成具有箱内成藏和箱外成藏两种成藏模式,前者具异常压力,为自源封闭成藏机制;后者为正常压力,为它源开放成藏机制,大多数为箱内成藏。(6)首次利用流体包裹体分析资料,结合烃源岩大量生排烃期、圈闭形成史,提出博兴地区具有两期成藏,晚期为主的特点,主要成藏期为晚第三纪馆陶一明化镇时期,北部及东部烃源岩层系中的油气藏形成相对较早;而西部和南斜坡金家地区油气藏形成较晚,主要成藏期大致在明化镇组沉积中后期,并延续至第四纪。(7)系统分析了油气富集的基本规律及主要控制因素,提出油气主要富集于汁-陷中部及边部的正向构造带,油气分布受构造背景、断裂、岩性、地层不整合、区-域性盖层等多种因素控制,明确了油气勘探的目标。
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基于二氢烷氧苄基嘧啶酮(DABO)类非核苷类逆转录酶抑制剂(NNRTIs)的构效关系研究,设计合成了2个新的6-(1H-吲哚-3-甲基)-5-乙基-3H-嘧啶-4-酮类化合物,并采用C8166细胞进行了体外抗HIV活性测试,为新型S-DABO类非核苷类逆转录酶抑制剂结构修饰提出了新的设想.
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本文研究了TritonX-100在浊点条件下对钴-4-(5-氯-2-吡啶偶氮)-1,3-二氨基苯(5-Cl-PADAB)络合物的析相条件,在pH4.0~6.0介质中,将胶束溶液加热到92±1℃,保持40min,络合物即被TritonX-100相富集。富集液在575nm测定吸光度,钴含量在0~4μg/5ml范围内服从比尔定律,干扰离子可在TritonX-100析相液中加入H_2SO_4消除。拟定的方法灵敏、简捷,已用于不经分离直接测定人发及自来水中痕量钴。
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This paper reports that the TM3+:Lu2SiO5 (Tm:LSO) crystal is grown by Czochralski technique. The room-temperature absorption spectra of Tm:LSO crystal are measured on a b-cut sample with 4 at.% thulium. According to the obtained Judd-Ofelt intensity parameters Omega(2)=9.3155 x 10(-20) cm(2), Omega(4)=8.4103 x 10(-20) cm(2), Omega(6)=1.5908 x 10(-20) cm(2), the fluorescence lifetime is calculated to be 2.03 ms for F-3(4) -> H-3(6) transition, and the integrated emission cross section is 5.81 x 10(-18) cm(2). Room-temperature laser action near 2 mu m under diode pumping is experimentally evaluated in Tm:LSO. An optical-optical conversion efficiency of 9.1% and a slope efficiency of 16.2% are obtained with continuous-wave maximum output power of 0.67 W. The emission wavelengths of Tm:LSO laser are centred around 2.06 mu m with spectral bandwidth of similar to 13.6 nm.
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A bulk crystal of Yb:Sc2SiO5 (Yb:SSO) with favorable thermal properties was successfully obtained by the Czochralski method. The energy level diagrams for Yb:SSO crystal were determined by optical spectroscopic analysis and semi-empirical crystal-field calculations using the simple overlap model. The full width at half maximum of the absorption band centering at 976 nm was calculated to be 24 nm with a peak absorption cross-section of 9.2x10(-21) cm(2). The largest ground-state splitting of Yb3+ ions is up to 1027 cm(-1) in a SSO crystal host. Efficient diode-pumped laser performance of Yb:SSO was primarily demonstrated with a slope efficiency of 45% and output power of 3.55 W.
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本论文依据主客体作用原理,从分子工程出发,主要利用各式杯芳烃主体与不同客体分子和金属离子进行组装,研究这类超分子的合成条件及规律,探讨主客体之间的相互影响及其自组装原理。 在第二章中,首先研究了银氨离子可诱导杯[4]芳烃(L1)形成超分子胶囊,接下来的工作中,我们对杯[4]芳烃进行修饰,合成了两种杯芳烃羧酸配体25, 26, 27, 28-tetrakis(carboxy methoxy)-calix[4]arene (L2) 和25, 26, 27, 28-tetrakis(carboxy methoxy)-p-t-butylcalix[4]arene (L3);并分别以六次甲基四胺和三苯基膦为中性配体,构筑了一个由胶囊构筑的三维网络结构和一个四核银的簇合物。 在第三章中,用六次甲基四胺作为中性配体与银离子和对磺酸杯[4]芳烃进行组装,得到了一个纳米孔材料,在该结构中,银与六次甲基四胺形成的配位多聚体作为模板,诱导对磺酸杯芳烃排列形成孔道。由于模板的作用,拉大了杯芳烃之间的距离。 在第四章中,用pnno (pyrazine-N,N’-dioxide)作为客体分子,在稀土离子存在的情况下与杯芳烃进行超分子组装。不同的实验方法分别得到了由超分子胶囊构筑的三维网络结构和A-B-A 的双层结构。稀土Nd与 5,11,17,23- tetrasulfonato- 25,26,27,28-tetra- ethoxycarbonylmethoxyl-calix[4]arene (L4)组装时,得到了一个由氢键连接的层状化合物。 在第五章中,在水溶液条件下,[M(bpdo)22H2O]2+ (M=Zn, Cu; bpdo=2, 2’- bipyridine-N, N’-dioxide )诱导对磺酸基杯[4]芳烃形成超分子胶囊;并且该胶囊通过电荷辅助的π•••π作用与[M(bpdo)3]2+组装成纳米孔材料,气体吸附的测试表明该纳米孔对甲醇有一定气体吸附能力。当用稀土离子代替金属离子时,形成了类似的超分子胶囊和孔状结构。结果表明稀土孔材料比过渡金属孔材料具有更好的热稳定性。进一步研究通过改变配体bpdo为tpdo (tpdo=terpyridine-1, 1’, 1’-trisoxide)得到了一个层状化合物。 在第六章中,将新型的有机配体与丙基焦杯芳烃或甲基间苯二酚杯芳烃进行自组装得到新奇的杯芳烃超分子结构。这些新型的有机配体含有N-O或C=O 官能团的有机分子4,4'-dipyridyl N, N'-dioxide (L5), tetra-2-pyridinyl-N, N', N", N"'-tetraoxide- pyrazine (L6) and 1, 10-phenanthroline-5, 6-dione (L7)。它们是具有特殊的氢键受体和空间构型的有机分子,由于氢键等弱相互作用在形成超分子结构中的重要作用,三种不同的有机配体与杯芳烃自组装得到了三种不同的杯芳烃超分子结构。
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本文采用室内培养、盆栽和田间试验相结合的方法,对3,5-二甲基吡唑的硝化抑制效果进行了初步探讨。结果表明,3,5-二甲基吡唑(DMP)的施用可以显著抑制土壤硝化作用的进行,其抑制效果受其本身用量及氮素用量的影响显著。但在常规氮施用量下,占纯氮量1.0%的DMP即可以起到显著的硝化抑制效果。在等N量和等抑制剂用量下,DMP的抑制效果显著优于双氰胺,而与3,4-二甲基吡唑磷酸盐效果相当。 对与氮转化有关的土壤酶活性影响结果表明,DMP只在施用后1~2天内对土壤脲酶活性具有短暂的抑制作用,但可较长时间显著抑制土壤硝酸还原酶活性,提高土壤亚硝酸还原酶活性。由于DMP的施用对土壤或肥料氮转化的有效调控,促进了作物对氮素的吸收累积,在生育期较长的水稻上效果更加显著。与对照相比,氮肥表观利用率提高了12.51%,水稻籽粒粗蛋白含量提高了6.24%。同时由于DMP的施用使土壤硝氮累积量显著降低,因此,土壤酸化程度及硝酸盐向土体下层的淋移趋势明显减缓。 对DMP施用后土壤微生物群落动态及微生物活性的研究结果表明,适量DMP的施用不会对表征土壤环境质量变化的土壤生物化学特性产生负面影响,而是通过专性抑制土壤氨氧化菌群落的增殖来实现其硝化抑制作用的,且对参与土壤氮素转化的亚硝酸氧化细菌和反硝化细菌影响很小。因此,DMP将是未来一种具有一定发展前景的土壤硝化作用的专一性抑制剂。