石墨炉原子吸收分光光度法测定茶叶中的铅

采用石墨炉原子吸收分光光度法测定了产自福建等地茶叶中的铅含量。方法的线性范围为0—80μg/L，回收率达91．7％-101．5％，相对标准偏差1．47％-3．88％。茶样检测结果表明，铅合格率为92．0％；不同茶类铅含量前3位由高到低依次为绿茶，乌龙茶，红茶；各类茶铅含量平均值为1．069mg／kg。     

ICP-OES法测成都市三环内表层土壤13种金属元素含量

采用电感耦合等离子体发射光谱(ICP-OES)法同时测定成都市三环内表层土壤13种金属元素含量与分布.研究显示,重金属元素As、Cr、Cu、Ni、Pb、Zn平均含量分别为24.3mg/kg,154.0 mg/kg,32.8 mg/kg,31.4 mg/kg,64.9 mg/kg,165.1 mg/kg.Mn、Mo、Fe平均含量分别为400.1 mg/kg,10.7 mg/kg,18911 mg/kg.Sr 74.0 mg/kg、Sb 4.9 mg/kg、Co 13.7 mg/kg、Sc 5.9 mg/kg.采用单项污染指数法和内梅罗综合污染指数法来评价土壤重金属污染程度,并针对表层土壤金属污染状况进行了讨论.     

微波消解-石墨炉原子吸收法研究益智及土壤中的铅含量

采用微波消解前处理方法,石墨炉原子吸收法研究了四大南药之一的益智不同器官及生长地土壤中重金属铅的含量。铅在益智不同器官内分布为:实根2.0244mg/kg、须根2.9428mg/kg、茎0.2232mg/kg、叶1.0228mg/kg、花0.0203mg/kg,果实中未检测出铅,土壤中铅含量分别为:表层26.2932mg/kg、中层24.4341mg/kg、深层12.3529mg/kg。结果表明,益智各器官及土壤中的铅含量远低于国家限量标准,说明海南地理环境有利于益智的种植。     

利用海藻中的碘培育富碘蔬菜防治IDD病的初步研究

以培育“绿色”富碘蔬菜，提高碘的土壤背景值，防治IDD病为目标，利用海带中的碘作为碘肥原料，进行了4种蔬菜的施碘实验。结果表明，通过施加硅藻土海藻碘肥，可培育出含碘量4～120mg/kg的叶菜类蔬菜(菠菜和白菜)和2～30mg/kg的果实类蔬菜(西红柿和萝卜)。不同作物对碘的富集能力不同，其由大到小顺序为：白菜，菠菜，西红柿和萝卜；不同部位对碘的吸收能力也不相同：叶子大于果实和根部。作物通过叶面从空气中吸收碘的能力和通过根部从土壤中吸收碘的能力相当。土壤对碘的保持能力有限，从低施肥量到高施肥量，碘在土壤中的残留率从50％下降到13％。就培育日常食用性蔬菜而言，适宜的施碘量为5～10mg/kg。     

茶叶中的铅污染问题

介绍了研究茶叶中铅污染的意义以及污染现状,从地域上和时间上阐述了茶叶铅污染现象的一般规律,从土壤母质、环境空气、农药化肥三个方面介绍可能导致茶叶铅含量超标的原因。     

洛阳市郊区叶菜中重金属含量抽样分析及评价

为了研究洛阳市郊区蔬菜中重金属污染状况,采用火焰原子吸收法对郊区李楼乡和孙旗屯乡抽取的叶菜样品中重金属Cu、Zn、Pb、Cd含量进行了测定。结果表明,8个蔬菜样品中Cu含量在0.393 9～0.970 7 mg/kg之间,Zn含量在1.395 0～10.080 0 mg/kg之间,均未超过国家蔬菜卫生限量标准;Pb含量在0.100 0～0.248 6 mg/kg之间,其中有3个样品Pb含量超出国家蔬菜卫生限量标准;Cd含量有5个样品未检出,其余3个样品也不超国标。经用单因子和综合因子污染指数评价,洛阳市郊区叶菜类蔬菜重金属污染大部分已处于警戒级到轻度污染,因此,应加强蔬菜中重金属污染的预防与治理工作。     

深圳市母乳中铅水平的调查分析

采用原子吸收法测定了深圳市300例母乳中的铅含量。结果表明,小于100μg/kg有297人,100～317μg/kg有3人;深圳市2月龄母乳喂养的婴儿在铅含量水平上是处于安全喂养水平,但是以私家车作为主要外出工具的受试者乳铅含量水平要高于其它各组,因此需要加强深圳市儿童铅含量水平的长期监测和环境铅污染治理工作。     

广州员村地区0—6岁109例儿童发铅含量的调查分析

通过对广州员村109名0－6岁儿童铅含量测定，结果发现扣年龄组儿童发铅超标严重，男、女间及各年龄组间无明显差异。结论：重视铅污染对儿童健康的危害，加强对铅污染的普查及防治。     

铅同位素在示踪城市环境污染源研究中的应用

在分析铅同位素示踪环境铅污染源理论的基础上,以成都市为例,对成都市城市环境（土壤、大气降尘、主要水系沉积物）铅污染的主要来源进行了研究.结果表明,成都市城市环境污染主要来自于燃煤扬尘和汽车尾气排放.铅同位素示踪理论应用于城市环境污染源的研究,能够取得比较理想的结果.     

城市灰尘重金属含量对城市土壤重金属的影响--以金华市为例

为系统了解城市重金属污染特性,采集了金华市不同功能区的城市灰尘与城市土壤样品,获得重金属含量,并对数据进行了统计分析。结果表明：（1）灰尘中重金属含量均高于土壤,含量最高的 Mn,平均质量分数为770．62 mg/kg,其次为 Zn,为696．72 mg/kg。土壤中 Mn 元素质量分数最高,为537．60 mg/kg。（2）灰尘、土壤中重金属均为中等变异,且土壤变异程度高于灰尘,说明土壤中的重金属受外界扰动更大。（3）城市灰尘和土壤中 Zn 元素表现为显著正相关,说明其对土壤有影响, Cu、 Pb 和 Mn 表现为正相关, Nb 基本不相关, Cr 为负相关,但相关性均不显著。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.