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三七生长初期不同部位微量元素的含量测定 总被引:6,自引:1,他引:6
采用电感耦合等离子体发射光谱法(ICP-AES),对文山地区GAP种植及农户常规种植的生长初期三七不同部位中的微量元素Mg、P、Ca、Mn、Na、Fe、Co、Cu、Zn、Mo、Cr、Ni、Ge、Se等14种元素进行了测定分析。结果表明,三七的根、茎、叶中含有丰富的人体必需Mg、P、Ca、Mn、Na、Fe、Co、Cu、Zn、Mo、Ge、Se等有益元素,且P、Ca、Mg、Fe含量较高,Na、Mn、Co、Zn次之,Co、Mo、Cr、Ni、Ge、Se含量均较低。为三七GAP栽培标准和特征制订、三七道地药材的化学特征——化学指纹图谱的建立及研究提供理论依据。 相似文献
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ICP-AES法测定铜精矿中As、Sb、Bi、Ca、Mg、Pb、Co、Zn和Ni 总被引:4,自引:0,他引:4
提出采用ICP-AES法同时测定铜精矿中As、Sb、Bi、Ca、Mg、Pb、Zn、Ni、Co的分析方法:样品经王水 HF HClO4溶液后,直接测定。该方法测定As、Sb、Bi、Ca、Mg、Pb、Zn、Ni、Co的回收率在97.9%~102%之间,相对标准偏差在0.23%~2.5%之间。通过和国家标准物质比对及国家标准分析方法的比对,结果准确可靠,现该方法已用于本公司铜精矿的日常分析。 相似文献
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颜卿 《广东微量元素科学》2009,16(4):40-40
人们都想了解和掌握必需微量元素和宏量元素含量配合较为均衡的蔬菜。根据专家们的研究发现,在人们食用的蔬菜中,含人体必需宏量元素和微量元素适量同时较为均衡的蔬菜有20多种,它们是:白萝卜、胡萝卜、小白菜、小青菜、油菜、蕹菜、白茱苔、蒜苗、油角豆、马兰头、韭菜、苦瓜、芪椰菜、莴苣笋(茎)、山药、芦笋、蒜苔、藕、红辣椒、青辣椒等,这些蔬菜所含的人体必需微量元素如:Fe、Me、Zn、Cu、Se等和人体必需宏量元素如K、Na、Ca、Mg等都是中等量,并且含量都是比较均衡,为人们日常调配饮食,购买、 相似文献
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颜卿 《广东微量元素科学》2009,(8):60-60
人们都想了解和食用必需微量元素和宏量元素含量配合较为均衡的蔬菜。根据研究发现,在人们食用的蔬菜中,含人体必需宏量元素和微量元素适量同时较为均衡的蔬菜有20多种,它们是:白萝卜、胡萝卜、小白菜、小青菜、油菜、蕹菜、白茱苔、蒜苗、油角豆、马兰头、韭菜、苦瓜、芪椰菜、莴苣笋(茎)、山药、芦笋、蒜苔、藕、红辣椒、青辣椒等,这些蔬菜所含的人体必需微量元素如: 相似文献
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建立电感耦合等离子体发射光谱法同时测定固体生物质燃料中钾、钠、钙、镁、砷、铜、铁、锰8种元素的含量。样品采用5 mL硝酸溶液和2 mL过氧化氢溶液进行微波消解,在选定的仪器工作条件下进行测定。钠、钙、镁、砷、铜、铁、锰的质量浓度在0~5.0 mg/L,钾的质量浓度在0~50.0 mg/L范围内与光谱强度具有良好的线性关系,相关系数均大于0.999,方法检出限为0.002~0.022 mg/L。样品的加标回收率为91.9%~108.2%,测定结果的相对标准偏差为2.1%~6.8%(n=6)。该方法简便、快速、高效且准确,适用于固体生物质燃料中钾、钠、钙、镁、砷、铜、铁、锰的测定。 相似文献
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2008年高考理综全国卷(Ⅰ),陕西、湖北、湖南、安徽、福建、浙江、辽宁、江西、广西、河北、山西、河南等省区采用;理综全国卷(Ⅱ),黑龙江、吉林、内蒙古、甘肃、青海、云南、贵州、新疆、西藏等省区采用.这2套试卷的化学试题难度有明显的差异,本文做一对比分析. 相似文献
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An approach to the synthesis of dipeptide olefin isosteres using intermolecular olefin cross-metathesis is presented. In particular, a synthesis of the Pro-Gly isostere (1) is reported. Conversion of N-BOC-proline into the corresponding vinyl-substituted carbamate provides the N-terminal cross-metathesis partner (2). Methyl 3-butenoate (3) is employed as the C-terminal component. Treatment of the two partners in an optimized molar ratio affords the cross product 1 (83% yield). Three other examples are demonstrated to evaluate the potential of the approach. 相似文献
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Among the many types of transition-metal-catalyzed C-C bond-forming reactions, olefin metathesis has come to the fore in recent years owing to the wide range of transformations that are possible with commercially available and easily handled catalysts. Consequently, olefin metathesis is now widely considered as one of the most powerful synthetic tools in organic chemistry. Until recently the intermolecular variant of this reaction, cross-metathesis, had been neglected despite its potential. With the evolution of new catalysts, the selectivity, efficiency, and functional-group compatibility of this reaction have improved to a level that was unimaginable just a few years ago. These advances, together with a better understanding of the mechanism and catalyst-substrate interactions, have brought us to a stage where more and more researchers are employing cross-metathesis reactions in multistep procedures and in the synthesis of natural products. The recent inclusion of alkynes and hindered bicyclic olefins as viable substrates for bimolecular metathesis coupling, the discovery of enantioselective cross-metathesis and cross-metathesis in water, and the successful marriage of metathesis and solid-phase organic synthesis has further widened the scope of this versatile reaction. 相似文献
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A highly demanding cross-metathesis (CM) reaction for the formation of the C24-C25 trisubstituted olefin of dolabelide C has been optimized. A difference in reactivity between the E and Z enone isomers in this reaction was uncovered, and the selection of the Z isomer of the starting enone was critical for the success of the cross-metathesis. Application to the synthesis of the C16-C30 fragment of dolabelide C is reported. 相似文献
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The total synthesis of the nonadjacently linked bis-THF acetogenin bullatanocin (squamostatin C) is described. The synthetic strategy is a modular one based on three components, two mono-THF alkenes and a butenolide precursor, and the olefin cross-metathesis and Wittig olefination as the segment-coupling reactions. The synthesis confirms the structure of the natural product, and its convergent design makes it especially attractive for analogue synthesis. 相似文献
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Olefin cross-metathesis couples two alkenes to form complex molecules and has been widely used in solution-phase organic synthesis. However, this powerful method has rarely been used in solid-phase organic synthesis. Herein we report that olefin cross-metathesis is a synthetically viable method particularly when a traceless longer linker is inserted between solid support and reacting olefins. 相似文献
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Total synthesis of (+)-varitriol and its C6′-epimer have been achieved starting from commercially available d-(?)-ribose and o-anisic acid. The key steps involved are Corey Chaykovsky reaction, triethylamine mediated epimerization, and an olefin cross-metathesis. 相似文献
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[reaction: see text] A convergent approach to the synthesis of the bis-tetrahydrofuran (THF) components of the nonadjacently linked THF-containing acetogenins is illustrated in the synthesis of 2, a potential intermediate for the antitumor agent bullatanocin (squamostatin C). The plan centers on the olefin cross-metathesis of THF allylic alcohol derivatives 3 and 4 as the key segment coupling step and the assembly of 3 and 4 through the iodoetherification of 1,2-O-isopropylidene-5-alkene precursors. 相似文献
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Matthias Schuster Siegfried Blechert 《Angewandte Chemie (International ed. in English)》1997,36(19):2036-2056
Transition metal catalyzed C? C bond formations belong to the most important reactions in organic synthesis. One particularly interesting reaction is olefin metathesis, a metal-catalyzed exchange of alkylidene moieties between alkenes. Olefin metathesis can induce both cleavage and formation of C? C double bonds. Special functional groups are not necessary. Although this reaction—which can be catalyzed by numerous transition metals—is used in industry, its potential in organic synthesis was not recognized for many years. The recent abrupt end to this Sleeping-Beauty slumber has several reasons. Novel catalysts can effect the conversion of highly fictionalized and sterically demanding olefins under mild reaction conditions and in high yields. Improved understanding of substrate–catalyst interaction has greatly contributed to the recent establishment of olefin metathesis as a synthetic method. In addition to the preparation of polymers with fine-tuned characteristics, the metathesis today also provides new routes to compounds of low molecular weight. The highly developed ring-closing metathesis has been proven to be key step in the synthesis of a growing number of natural products. At the same time interesting applications can be envisioned for newly developed variants of bimolecular metathesis. Improvements in the selective cross-metathesis of acyclic olefins as well as promising attempts to include alkynes as viable substrates provide for a vivid development of the metathesis chemistry. 相似文献
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Total synthesis of the proposed structure 2 for phomopsin B was achieved by using an intramolecular olefin metathesis as a key step. The spectral data, however, did not match with those of the natural product reported. Re-examination of the reported NMR data led to the structural revision of phomopsin B to known dothiorelone A 18. The R configuration of dothiorelone A was determined by total synthesis through a cross-metathesis with a chiral olefin 19. 相似文献
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[reaction: see text] Trisubstituted alkenes have been prepared via intermolecular olefin cross-metathesis (CM) between alpha-olefins and symmetrically 1,1-disubstituted olefins using an imidazolylidene ruthenium benzylidene complex. Of particular interest is the synthesis of isoprenoid/prenyl groups by a simple solvent-free CM reaction with isobutylene. In addition, prenyl groups can also be installed by a cross-metathesis of 2-methyl-2-butene with a variety of alpha-olefins at room temperature with low catalyst loadings. 相似文献