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121.
Chromatographia - In the chemical characterization of medically valued Cannabis, the present work has used a gas chromatography (GC) method coupled with mass spectrometry (MS) for identification... 相似文献
122.
Undoped and doped ZnO with 1 at.% (atomic percentage) chromium (Cr) was synthesized by RF reactive co-sputtering for oxygen gas sensing applications. The prepared films showed a highly c-oriented phase with a dominant (0 0 2) peak at a Bragg angle of around 34.2°. The operating temperature of the prepared ZnO sensor was around 350 °C and shifted to around 250 °C for the doped ZnO sensor which is lower than that of previously reported work. The sensitivity of the sensor toward oxygen gas was enhanced by doping ZnO with 1 at.% Cr. Good stability and repeatability of the sensor were demonstrated when tested under different concentration of oxygen atmosphere. 相似文献
123.
[reaction: see text] The synthesis of primary amines via reductive amination of the corresponding carbonyl compounds with aqueous ammonia is achieved for the first time with soluble transition metal complexes. Up to an 86% yield and a 97% selectivity for benzylamines were obtained in the case of various benzaldehydes by using a Rh-catalyst together with water-soluble phosphine and ammonium acetate. In the case of aliphatic aldehydes, a bimetallic catalyst based on Rh/Ir gave improved results. 相似文献
124.
Waheed A Jones RA McCarty J Yang X 《Dalton transactions (Cambridge, England : 2003)》2004,(22):3840-3841
Reaction of Zn(OAc)(2).2H(2)O with pyrazine in refluxing ethanol gives the unusual heptanuclear complex Zn7(mu4-O)(2)(OAc)(10)(Pz)(2) (1) (OAc = acetate, Pz = pyrazine) in 46% yield. A single-crystal X-ray diffraction study of revealed a central Zn(7) core in which two pseudo-tetrahedral Zn(4) units are joined at a common vertex. The two pyrazine molecules are bound as terminal (eta1) ligands. 相似文献
125.
Riaz N Anis I Malik A Ahmed Z Aziz-ur-rehman Muhammad P Nawaz SA Choudhary MI 《Chemical & pharmaceutical bulletin》2003,51(3):252-254
Paeonins A and B, new monoterpene galactosides have been isolated from the chloroform-soluble fraction of the roots of Paeonia emodi and showed potent lipoxygenase inhibitory activity. The structures of 1 and 2 have been assigned on the basis of spectral analysis including one- and two-dimensional NMR techniques. 相似文献
126.
The nucleophilic cleavage of alpha-amino acetals induced by TMSOTf can be used to prepare a wide range of substituted 1,2-aminoethers. In particular, organometallic reagents, N-heterocycles, and enamines all react efficiently to give products in good yield. In appropriate cases, good levels of stereocontrol are possible, but this is very dependent on the nature of the nucleophile and the substrate, with diethylzinc proving particularly effective across a range of substrates. The degree of stereocontrol can be used to infer the nature of the reactive intermediates involved in the reaction. With diethylzinc, it is most likely that the reaction proceeds by coordination of the nucleophile to the amino group followed by transfer of an ethyl group to an alpha-oxocarbenium ion. With non-coordinating nucleophiles, the stereochemical outcome can be rationalised in terms of addition to the possible alpha-alkoxy aziridinium ion intermediates. 相似文献
127.
报道了在兰州重离子加速器国家实验室电子回旋共振离子源原子物理实验平台上,用高电荷态40Arq+(1≤q≤12)离子作用于半导体Si固体表面时的电子发射产额实验测量.实验中,通过改变炮弹离子的电荷态和引出电压选取其不同的势能和动能,系统地研究了入射离子势能沉积和与其在固体中的电子能损对表面电子发射产额的贡献.结果表明,作为引起表面电子发射的两个主要因素,单离子的电子发射产额与炮弹离子在固体表面的势能沉积和电子能损都有近似的正比关系. 相似文献
128.
Abdul Manaf Hashim Seiya Kasai Kouichi Iizuka Tamotsu Hashizume Hideki Hasegawa 《Microelectronics Journal》2007,38(12):1268-1272
Theoretical analysis of potential distribution in the interdigital-gated high electron mobility transistor (HEMT) plasma wave device was carried out. The dc I–V characteristics of capacitively coupled interdigital structure showed that uniformity of electric field under the interdigital gates was improved compared to the dc-connected interdigital gate structure. Admittance measurements of capacitively coupled interdigital gate structure in the microwave region of 10–40 GHz showed the conductance modulation by drain–source voltage. These results indicate the existence of plasma wave interactions. 相似文献
129.
Afaq Shagufta Khan Sadia Kazmi Mehdi Hassan Fatima Itrat Malik Abdul Inamullah Farah Farhad Zahid Abbas Tanveer Tareen Rasool Bakhsh 《Chemistry of Natural Compounds》2021,57(2):269-273
Chemistry of Natural Compounds - Armatans A (1) and B (2), new isoflavans, have been isolated from the EtOAc-soluble fraction of the MeOH extract of Colutea armata Hemsl. & Lace, along with... 相似文献
130.
Muhammad Aslam Mirza Abdul Jabbar Kandhro Muhammad Yar Khuhawar Rafee Arain 《Journal of separation science》2009,32(18):3169-3177
An analytical procedure has been developed for the separation of Cu(II), Ni(II), Co(II), Fe(II), Pd(II), Th(IV), V(IV), and determination of Fe(II), Co(II), Ni(II), and V(IV) by MEKC after chelation with bis(salicylaldehyde)tetramethylethylenediimine (H2SA2Ten). Uncoated fused silica capillary was used with an applied voltage of 30 kV with photo‐diode array detection at 228 nm. SDS was added as micellar medium at pH 8.2 with sodium tetraborate buffer (0.1 M). Linear calibrations were established within 0.015–1000 μg/mL of each element with LOD within 5–67 ng/mL. The method was applied for the determination of vanadium from crude oil and ore samples in the range 0.34–2.40 and 114.2–720.7 μg/g with RSD 1.7–3.8 and 0.98–2.30% (n = 3), respectively. Fe, Ni, and Co present in crude oil and ore samples were also determined with RSD 1.3–2.8, 1.1–4.1, and 1.2–3.5% (n = 3), respectively. The results were compared with that of supplier's specifications and atomic absorption spectrometry (AAS). Method was evaluated by standard addition technique. 相似文献