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排序方式: 共有74条查询结果,搜索用时 15 毫秒
1.
Lanthanum, cerium, neodymium, samarium, europium, gadolinium, dysprosium, erbium, ytterbium, lutetium and yttrium have been determined in 8 international rock standards by inductively coupled plasma atomic emission spectrometry (ICP-AES) without prior ion-exchange separation and preconcentration. The results for La, Ce, Nd, Eu, Dy, Yb and Y were in good agreement with the reported values, whereas those for Sm, Gd, Er and Lu were less accurate. However, the results for Sm, Gd, Er and Lu can also be used for studies of petrogenesis. 相似文献
2.
B. S. Randhawa R. Kaur K. Sweety 《Journal of Radioanalytical and Nuclear Chemistry》1997,220(2):271-273
Thermal decomposition of some hydroxy iron(III) carboxylates, i.e., iron(III) lactate, Fe(CH3CHOHCOO)3, iron(III) tartrate, Fe2(C4H4O6)3 and iron(III) citrate, Fe(C6H5O7) · 5H2O has been studied in static air atmosphere in the temperature range 298–773 K employing Mössbauer, infrared spectroscopies and themogravimetric methods. The compounds directly decompose to -Fe2O3 without undergoing reduction to iron(II) intermediates. An increase in particle size of -Fe2O3 has been observed with increasing decomposition temperature. The thermal stability follows the sequence: iron(III) tartrate > iron(III)citrate > iron(III)lactate. 相似文献
3.
Organic ammonium tribromide (OATB), N-methylpyrrolidine-2-one hydrotribromide (MPHT) was found to be an efficient catalyst for the regioselective ring opening of epoxides with various nucleophiles under solvent free conditions. This procedure occurs under neutral and mild reaction conditions with out adding any additive and afforded high yields of products.
4.
The utilization of therapeutic plants is expanding around the globe, coupled with the tremendous expansion of alternative medicine and growing demand in health treatment. Plants are applied in pharmaceuticals to preserve and expand health—physically, mentally and as well as to treat particular health conditions and afflictions. There are more than 600 families of plants identified so far. Among the plants that are often studied for their health benefit include the genus of Salvia in the mint family, Lamiaceae. This review aims to determine the bioactive components of Salvia and their potential as antidiabetic agents. The search was conducted using three databases (PubMed, EMBASE and Scopus), and all relevant articles that are freely available in the English language were extracted within 10 years (2011–2021). Salvia spp. comprises many biologically active components that can be divided into monoterpenes, diterpenes, triterpenes, and phenolic components, but only a few of these have been studied in-depth for their health benefit claims. The most commonly studied bioactive component was salvianolic acids. Interestingly, S. miltiorrhiza is undoubtedly the most widely studied Salvia species in terms of its effectiveness as an antidiabetic agent. In conclusion, we hope that this review stimulates more studies on bioactive components from medicinal plants, not only on their potential as antidiabetic agents but also for other possible health benefits. 相似文献
5.
B. S. Randhawa K. J. Sweety Manpreet Kaur J. M. Greneche 《Journal of Thermal Analysis and Calorimetry》2004,75(1):101-111
Thermal analysis of some transition metal ferrimaleate precursors, M3[Fe(mal)3]2·xH2O (M=Mn, Co, Ni, Cu) has been studied in static air atmosphere from ambient to 600°C. Various physico-chemical techniques, i.e. TG, DTG, DTA, XRD, IR, Mössbauer spectrometry, have been employed to characterize both the intermediates and final products. After dehydration the anhydrous precursors undergo decomposition to yield an iron(II) intermediate, M[FeII(mal)2] (M=Mn, Co, Ni, Cu) in the temperature range 160-275°C. A subsequent oxidative decomposition of iron(II) species leads to the formation of -Fe2O3 and MO in the successive stages. Finally a solid-state reaction occurs between the oxides above 400°C resulting in the formation of transition metal ferrites, MFe2O4. The ferrites have been obtained at much lower temperature and in less time than in the conventional ceramic method.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
6.
Hong Li Sahas Rathi Elizabeth S. Sterner Hui Zhao Shaw Ling Hsu Patrick Theato Yongming Zhang E. Bryan Coughlin 《Journal of polymer science. Part A, Polymer chemistry》2013,51(20):4309-4316
The synthesis and characterization of a photocleavable block copolymer containing an ortho‐nitrobenzyl (ONB) linker between poly(methyl methacrylate) and poly(d ‐lactide) blocks is presented here. The block copolymers were synthesized via atom transfer radical polymerization (ATRP) of MMA followed by ring‐opening polymerization (ROP) of d ‐Lactide and ROP of d ‐lactide followed by ATRP of MMA from a difunctional photoresponsive ONB initiator, respectively. The challenges and limitations during synthesis of the photocleavable block copolymers using the difunctional photoresponsive ONB initiator are discussed. The photocleavage of the copolymers occurs under mild conditions by simple irradiation with 302 nm wavelength UV light (Relative intensity at 7.6 cm: 1500 μW/cm2) for several hours. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4309–4316 相似文献
7.
Dr. Hyewon Lee Rathi L. Srinivas Ankur Gupta Prof. Patrick S. Doyle 《Angewandte Chemie (International ed. in English)》2015,54(8):2477-2481
Although microRNAs (miRNAs) have been shown to be excellent indicators of disease state, current profiling platforms are insufficient for clinical translation. Here, we demonstrate a versatile hydrogel‐based microfluidic approach and novel amplification scheme for entirely on‐chip, sensitive, and highly specific miRNA detection without the risk of sequence bias. A simulation‐driven approach is used to engineer the hydrogel geometry and the gel‐reaction environment is chemically optimized for robust detection performance. The assay provides 22.6 fM sensitivity over a three log range, demonstrates multiplexing across at least four targets, and requires just 10.3 ng of total RNA input in a 2 hour and 15 minutes assay. 相似文献
8.
Utkarsha Shedbalkar Richa Singh Sweety Wadhwani Sharvari Gaidhani B.A. Chopade 《Advances in colloid and interface science》2014
Gold nanoparticles have been employed in biomedicine since the last decade because of their unique optical, electrical and photothermal properties. Present review discusses the microbial synthesis, properties and biomedical applications of gold nanoparticles. Different microbial synthesis strategies used so far for obtaining better yield and stability have been described. It also includes different methods used for the characterization and analysis of gold nanoparticles, viz. UV–visible spectroscopy, Fourier transform infrared spectroscopy, X ray diffraction spectroscopy, scanning electron microscopy, ransmission electron microscopy, atomic force microscopy, electron dispersive X ray, X ray photoelectron spectroscopy and cyclic voltametry. The different mechanisms involved in microbial synthesis of gold nanoparticles have been discussed. The information related to applications of microbially synthesized gold nanoparticles and patents on microbial synthesis of gold nanoparticles has been summarized. 相似文献
9.
The olefin cross-metathesis reaction provides a rapid and efficient method for the synthesis of α,β-unsaturated 1,5-dicarbonyl derivatives which then serve as effective precursors to mono-tetrasubstituted pyridines. Manipulation of the key 1,5-dicarbonyl intermediate allows access to pyridines with a wide range of substitution patterns. An extension of this methodology facilitates the preparation of pyridines embedded within macrocycles, as exemplified by an efficient synthesis of (R)-(+)-muscopyridine. High levels of regiocontrol, short reaction sequences, and facile substituent variation are all notable aspects of this methodology. 相似文献
10.
Prof. Timothy J. Donohoe Adam R. Lacy Akshat H. Rathi Dr. Daryl S. Walter 《化学:亚洲杂志》2011,6(12):3214-3222
A new strategy that employs an exocyclic stereocenter to effect diastereocontrol in the tethered aminohydroxylation (TA) reaction is applied to the stereoselective synthesis of a range of amino alcohols in good to excellent yields, and with anti selectivities of up to 20:1. The influence of the reaction conditions and substrate parameters on the level of diastereocontrol is described. Furthermore, an “inside alkoxy” model is employed to rationalize the sense and degree of stereoselectivity observed in these systems. 相似文献