有机合成的新世纪――－有机合成近年进展鉴赏

本文简要介绍了2005年至今有机合成领域的进展,第一部份有机合成方法学的一些新进展中突出介绍了金属参与的有机合成反应、自由基介导的合成反应、"一个反应瓶"内的多步反应以及不对称反应四个方面;第二部份复杂天然产物全合成则以10个分子的为例介绍这方面的进展。     

有机磷化合物的研究 66.亚磷酸二酯对碳氮双键诱导不对称加成反应的分子力学研究

本文应有MNDO和MM2(85)研究了亚磷酸二酯对碳氮双键的诱导不对称加成反应的结构效应,催化剂种类和浓度以及溶剂等因素对诱导方向及de值的影响.结果表明,反应的诱导方向及诱导效果强烈地受到在反应过渡态中诱导基团的苯环与催化剂配合作用的影响.当苯环不参与配合时,诱导产物以R构型为主;当苯环参与配合时,诱导产物以S构型为主.该模型解释了催化剂种类和浓度、溶剂及酯烷基等结构效应.     

模拟地热水中304不锈钢管和镀锌钢管的腐蚀与结垢

采用扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)和电化学测试的方法研究了304不锈钢管和镀锌钢管在模拟地热水(我国中部平原地热水的环境条件)中的腐蚀与结垢行为.结果表明,不锈钢管的结垢产物为"针"状物,其组成主要为CaCO3和MgCO3;镀锌钢管的腐蚀与结垢产物为"球"状物和"针"状物,其组成主要为Zn(OH)2、ZnO和CaCO3;腐蚀产物与结垢产物在晶核的形成生长过程中往往存在相互作用,同时它们在基材表面的分布对镀锌钢管的进一步腐蚀产生一定的抑制作用.     

有机磷化合物的研究 66.亚磷酸二酯对碳氮双键诱导不对称加成反应的分子力学研究

本文应用MNDO和MM2(85)研究了亚磷酸二酯对碳氮双键的诱导不对称加成反应的结构效应,催化剂种类和浓度以及溶剂等因素对诱导方向及de值的影响.结果表明,反应的诱导方向及诱导效果强烈地受到在反应过渡态中诱导基团的苯环与催化剂配合作用的影响.当苯环不参与配合时,诱导产物以R构型为主;当苯环参与配合时,诱导产物以S构型为主.该模型解释了催化剂种类和浓度、溶剂及酯烷基等结构效应.     

2-吡喃酮的催化不对称Diels-Alder反应研究进展

2-吡喃酮是一种含有共轭二烯的杂环化合物,它可以作为一种特殊的双烯体参与Diels-Alder反应.经过几十年的发展,2-吡喃酮的Diels-Alder反应在复杂天然产物的合成中得到了广泛地应用.近年来,2-吡喃酮的催化不对称Diels-Alder反应也引起了合成化学家的关注.对2-吡喃酮参与的不对称正电子需求和反电子需求的Diels-Alder反应的发展,以及它们在天然产物全合成中的应用进行了总结.     

锡粉促进下α-酰肼基-γ-戊烯酸乙酯的合成

探索了锡粉促进下,乙醛酸乙酯、酰肼和烯丙基溴的"一锅法"反应.各种酰肼都能参与反应并以高产率生成α-酰肼基-γ-戊烯酸乙酯.当异戊烯基溴和巴豆基溴代替烯丙基溴反应时,得到的都是γ-加成产物.该反应提供了一种合成α-酰肼基-γ-戊烯酸酯化合物的新方法.     

有机叠氮化合物参与的反应:C—N3基团保留的研究进展

有机叠氮化合物在天然产物全合成、药物化学以及材料化学等领域有广泛的应用.叠氮基团在反应过程中倾向于脱除氮气,转化为多种多样的含氮杂环以及氨基类化合物,但在许多天然产物全合成的关键步骤中,都需要保留叠氮基团.总结了近二十年有机叠氮化合物参与的反应中C—N₃键保留的反应类型,主要包括环加成反应、与不饱和键的加成、Winstein重排和1,2-叠氮迁移等.     

来源于天然产物的基质金属蛋白酶(MMPs)抑制剂

基质金属蛋白酶（MMPs）参与一系列重大疾病的病理过程,基质金属蛋白酶抑制剂具有广阔的药用前景。本文概述了基质金属蛋白酶抑制剂的研究历史和最新的研究理念。重点回顾总结了天然产物中基质金属蛋白酶的活性抑制成分和对基质金属蛋白酶转录表达抑制的天然产物成分以及这些化合物的抗癌效果。     

化学教学过程中学生参与现状的调查分析

借助"学生参与"量表编制化学教学过程中学生参与现状调查表,对学生进行前测和后测,调查分析学生参与的现状,并就教师在实施参与策略前后学生的参与现状进行对比分析,同时对调查结果进行了反思。     

基于“异氰基双官能团化”策略构建嘧啶二酮骨架

正Angew.Chem.Int.Ed.2018,57,5720～5724异氰基中碳原子特有的反应性质使得异腈能参与许多类型的有机反应.就异氰基的官能团化而言,大部分的反应仅涉及到碳原子的官能团化.毫无疑问,同时实现异氰基中碳原子和氮原子的官能团化将极大地丰富产物的结构类型.第三军医大学药学与检验医学系魏晔课题组首次提出"异氰基双官能团化"策略,采用环状肟酯和异腈为起     

Analytical strategies to determine antibiotic residues in fish

The accelerated growth of aquaculture has resulted in a series of harmful effects to human health. The widespread and unrestricted use of antibiotics in this industry, to prevent bacterial infections, leads to remaining amounts in the aquatic environment. This has resulted in the emergence of antibiotic-resistant bacteria in aquaculture environments, in the increase in antibiotic resistance in fish pathogens as well as in the transfer of these resistance determinants to human pathogens. Moreover, the use of large amounts of antibiotics may lead to the presence of residual antibiotics in fish tissue and fish products. Fluoroquinolones, tetracyclines, penicillins, sulphonamides and other antibiotics, exhibiting activity against both Gram-positive and Gram-negative bacteria, are widely used for the treatment and prevention of diseases in fish. An extended and comprehensive review on the recent analytical methodologies concerning antibiotic residues in fish reported in the literature is provided in the present article. Emphasis is given on sample preparation regarding isolation and purification, chromatographic conditions and method validation according to legislation. Results of published assays are comparatively presented and criticised.     

石柱黄连及根际土壤中矿质元素特征分析

研究石柱黄连不同器官及其根际土壤中矿质元素特征,探究黄连根茎矿质元素间及其与土壤环境的相关性。采用电感耦合等离子体质谱法(ICP-MS)、电感耦合等离子体发射光谱法(ICP-OES)及原子荧光光谱法(AFS)测定了15组石柱黄连植株和根际土壤中18种矿质元素含量,所得数据运用SPSS 22.0统计软件分析。石柱黄连根际土壤中锰、磷、镁、镉、汞等元素含量的变异性较大,部分采样点土壤中镉含量超过农用地土壤污染风险筛选值。在检测的18种元素中,黄连植株中钙、镁、磷、钾含量最高,其次是铁、锰、锌,再次是锶、铜、镍,最后是铅、钒、钴、镉、钼、铬、砷、汞。须根对大部分矿质元素的富集能力强于根茎或地上部;黄连根茎对锌的富集能力强于须根或地上部;地上部对钙、磷、钾、铬的富集能力强于须根或根茎。Spearman分析表明黄连根茎矿质元素间、黄连根茎与土壤中矿质元素有一定相关性,部分具有统计学意义(P＜0.05)。石柱黄连不同器官中矿质元素含量有明显差异,以此建立的指纹图谱可用于区分黄连根茎及须根的粉末样品;黄连根茎中矿质元素间主要表现为协同作用,黄连根茎与土壤中矿质元素既有协同作用又有拮抗作用。     

青藏高原湖泊影响锂元素迁移和富集的矿物、元素及环境因素——以西藏郭扎错钻孔沉积物为例

作为我国战略性矿产的锂矿,主要赋存于青藏高原盐湖中。湖泊系统中,锂的富集和迁移规律关系到锂矿的高效提取和未来锂矿的储量估算。本文以西藏咸水湖郭扎错的钻孔沉积物为例,结合AMS14C年代和Mg元素含量变化,系统分析了孔隙水、碳酸盐矿物和硅酸盐矿物的锂含量变化,探讨了矿物、镁元素、环境变化和早期成岩作用等对锂元素迁移和富集的影响。郭扎错沉积物中锂和镁大部分存在于硅酸盐矿物中,锂和镁较高的相关性说明二者存在于相同的硅酸盐矿物中,如粘土矿物。大约90%的锂赋存在硅酸盐矿物中,约8.5%的锂赋存在碳酸盐矿物中,孔隙水中的锂含量占比仅约1.5%。碳酸盐矿物中Mg/Li摩尔比值为78–270,是孔隙水中10多倍,而硅酸盐矿物中的Mg/Li摩尔比值稳定在24–29之间。水–沉积物相互作用促进硅酸盐矿物中锂的释放,咸水环境下释放的锂多于淡水环境下。碳酸盐矿物中,锂和镁主要存在于方解石中。镁离子对锂离子的迁移具有阻碍作用,低温、高盐度下的阻碍作用更强。湖泊沉积物可能是湖水锂的一个重要来源。     

Effects of dilute acid and steam explosion pretreatments on the cellulose structure and kinetics of cellulosic fraction hydrolysis by dilute acids in lignocellulosic materials

Worldwide, yellows diseases impact plants important in human nutrition, the natural environment, and the culture and commerce of humans. Since the presumed pathogens, mycoplasma-like organisms (MLOs), have not been isolated in pure culture in vitro, their study must proceed by other experimental approaches. In a study of disease affecting grapevines in Europe and North America, polymerase chain reactions (PCR) and restriction analyses of PCR-amplified DNA were used to detect and differentiate strains of MLOs associated with grapevine yellows. MLOs were detected both in naturally diseased grapevines and in experimentally inoculated host plants. The data indicated an unexpected genomic diversity among grapevine-infecting MLOs, and supported their classification with MLOs in the aster yellows, X-disease, and elm yellows groups. The presence of diverse MLOs in grapevines provokes consideration that these MLOs may be present in overlapping geographic ranges and that multiple MLO infections may occur in individual plants, increasing the complexity of grapevine yellows epidemiology and control and the significance of sensitive MLO detection in planting stock and phytosanitary-regulated germplasm.     

煤烘玉米和饮水为介质地氟病区骨畸形病人全血尿多元素含量的分析

采集了贵族个煤烘玉米为主要介质和河北２个饮水为介质氟病区内骨畸形病人的全血、尿、检测了其中８种元素含量,结果表明,贵州各氟病区少儿骨软化与成年骨硬化畸形病人的全血铝、钙、磷、铁和尿氟、铝均显著高于同龄对照组,尿磷均低于同龄对照组。少儿骨软化病人全血锌均下降,尿锌多下降。某水型氟病区骨软化经产妇尿氟、全血铜升高;骨软化少年全血铝显著升高,锌、铁下降,尿氟升高,尿锌,磷下降。海边的典型氟骨症病人全血、     

延边地区65～108岁健康老人头发中锌、铜、铁、锰、镁的含量

用原子吸收光谱法测定延边地区317名65～108岁老人头发中锌、铜、铁、锰、镁含量，观察不同民族、性别、年龄老人这些元素的差异。结果表明：1.朝鲜旗发锌低于汉族，满族发铜低于汉族、朝鲜族，汉族发镁高于朝鲜族、满族，发铁、发锰在汉、朝、满民族之间无区别。2．汉族、朝鲜族男发锌高于女性，汉族女性发铜高于男性，发铁、发锰、发镁在性别之间无区别。3、90岁组朝鲜族发锰、发镁低于65岁、76岁组，朝鲜族发锌、发铜、发铁在65～108岁之间无统计学意义。     

谈科学探究中的归纳与演绎

逻辑推理过程与事物的认识过程同时存在,科学探究离不开逻辑推理过程。归纳和演绎是认识过程中的两种逻辑推理形式,在学生的科学探究活动中,尤其是在提出问题、猜想与假设、设计实验方案与解释结论阶段,归纳和演绎发挥着重要的作用。本文重点论述了寻求现象原因的求异归纳推理、探寻化学物质通性及变化规律的不完全归纳推理、探求个别物质性质的演绎三段论、解释个别现象的演绎解释推理过程在科学探究中的重要作用。     

GC-MS analysis of penta- and tetra-cyclic triterpenes from resins of Pistacia species. Part II. Pistacia terebinthus var. Chia

Pistacia species contain oleoresins with bioactive triterpenes. In this study triterpenes, including minor components, were identified and quantified in both neutral and acidic fractions of Pistacia terebinthus var. Chia resin, grown exclusively in Chios island (Greece), collected traditionally, as well as using stimulating agents (liquid collection). It was proved that these two resin samples were composed of several different minor triterpenes, while major constituents were similar but in different proportions. Compounds that differentiated two resin samples of P. lentiscus and P. terebinthus var. Chia, both traditionally collected, were detected, in order to identify the nature of resins present in archaeological materials. In the traditionally collected resin, 37 triterpenes were identified, 12 in the acidic and 25 in the neutral fraction. In the liquid collection resin 10 compounds were identified in the acidic and 23 in the neutral fraction, while 16 compounds were not contained in the traditionally collected resin. The main triterpenes in both resin samples collected traditionally and using stimulating agents were: isomasticadienonic acid (23.6 and 26.3% w[sol ]w of the triterpenic fraction, respectively), 28-norolean-17-en-3-one (16.3 and 17.5% w[sol ]w of the triterpenic fraction, respectively) and masticadienonic acid (5.8 and 6.0% w[sol ]w of the triterpenic fraction). In this study the qualitative and quantitative composition of triterpenes was compared in the Pistacia lentiscus and P. terebinthus var. Chia resin samples collected with the traditional and new liquid techniques, and also triterpenes in resins of P. terebinthus obtained by the traditional technique and using stimulating agents. The aim of the study was also to examine whether the collection technique influenced the triterpenes contained in P. terebinthus var. Chia resin samples.     

Physiological changes in barley plants under combined toxicity of aluminum, copper and cadmium

Crop production on acid soil is markedly reduced, further, a multiple heavy metal pollution except Al on acid soil is detected in many areas. The present study was undertaken to assess the toxicities of Al, Cd, and Cu separately and in combinations, three heavy metals very often coexisting on acid soil, and to identify their interactions in two kinds of barley seedlings differing in Al tolerance. The plant growth, metals accumulations, total soluble protein and sugar contents, MDA contents and the activities of SOD and POD were estimated in roots and leaves after 5-week supply of the heavy metals excess in the nutrient solution. The results indicated that the stress treatments including low pH (pH 4.5) alone all adversely affected plant growth and disturbed the cell metabolism seriously. The development of toxic symptoms corresponded to a high accumulation of Al, Cd, Cu and to a poor increase in soluble sugar contents but to a high increase in MDA contents, to the decrease in soluble protein contents and to the much elevated SOD and POD activities in both roots and leaves. In addition, binary metal combinations of Al + Cd and Al + Cu both produced the synergistic response for the growth of barley seedlings, in particular for Shang 70-119, while, ternary metal combination of Al + Cu + Cd produced different interactions in two kinds of genotypes, thus, the significant synergistic response was seen in Shang 70-119, but the antagonistic response was detected in Gebeina. The different responses to ternary metal combination of two genotypes may result from the different metal bioaccumulation patterns, hence, the existence of Cd and Cu promoted Al accumulation in Shang 70-119 but inhibited Al accumulation in Gebeina.     

Zinc in gastrointestinal and liver disease

Zinc is an essential trace element with important biological functions, depending on the structural and/or catalytic role played by zinc ions in a large variety of enzymes. Zinc plays a critical role in cellular integrity, protein synthesis, nucleic acid metabolism, contributing to cell growth, proliferation, differentiation and death. The present review reports data on zinc homeostasis and metabolism, zinc absorption, intercellular trafficking, intracellular transport inside enterocytes and hepatocytes. Particular emphasis is given to data regarding the role of zinc carriers ZnTs and Zips, and to their expression in liver and gut in experimental and in human studies. The role of zinc in the gastrointestinal tract and in the liver as a powerful antioxidant and its relationship with apoptosis is discussed. Possible implications of zinc status in different disorders of the gastrointestinal tract are presented, focusing on its possible introduction in the therapy of inflammatory bowel diseases. Data on the role of zinc and zinc carriers in the evolution of liver fibrosis towards cirrhosis are also discussed. Finally, data on the ability of zinc therapy to obtain regression of liver cirrhosis in patients affected by Wilson's disease are reported, and the hypothesis that zinc could protect against liver fibrosis in chronic liver disease of different origin is presented.