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141.
[reaction: see text] The silver(I)-catalyzed reaction of alkynones with alcohols represents a general tool for the synthesis of 1-allenyl isochromenes. The reaction most probably proceeds via the formation of benzopyrylium cation, which subsequently undergoes nucleophilic attack of an alcohol to give the annulation products. 相似文献
142.
The Calf Antibiotic and Sulfonamide Test (CAST), a microbial inhibition screening test, was developed for detecting antibiotics and sulfonamides in bob veal calf carcasses. The test uses Bacillus megaterium ATCC 9885 as the indicator organism and Mueller Hinton agar as the growth medium. Compared to Swab Test on Premises (STOP), developed in 1970, this screening test has higher sensitivity and the ability to detect a wider range of veterinary antimicrobial residual drugs, particularly sulfonamides, at lower concentrations. Carcasses that are tested with CAST and suspected of containing chemical residue above tolerance level are retained for confirmation. Disposition of these carcasses are determined upon laboratory result. Routine testing of bob veal calves with CAST allowed the Food Safety and Inspection Service to release most calf carcasses within 24 h post-slaughter, thus conserving shipping and handling resources. However, changes in the regulation in 1990 dictate that disposition of carcasses found to contain violative levels of sulfonamide residues should be based on laboratory findings. The analysis of the data for the years 1990-1994 and 1998 indicate that the use of CAST over the years was significant, and had a direct impact on reduction of residue violations in veal carcasses. With the use of CAST, potentially harmful antimicrobial chemicals entering the human food chain through veal meat have been minimized. 相似文献
143.
Structural assignment and molecular order of three-ring mesogen by 13C NMR spectroscopy in mesophase
A homologous series of rod-like molecules with three phenyl rings in the core and terminal alkoxy chains are synthesised from mesogenic two-ring aldehyde by coupling with non-mesogenic 4-alkoxy anilines. The mesophase properties are evaluated with hot-stage optical polarising microscopy and differential scanning calorimetry, and accordingly, all the molecules exhibited enantiotropic nematic and smectic C phases along with monotropic low-temperature smectic phases. For a representative homologue, the existence of smectic C phase is further confirmed by noticing a sharp reflection at small angle region in powder X-ray diffraction which varies with change in temperature. The main focus of the investigation, however, is the clear demonstration of chemical shift assignment of static 13C NMR of a representative three-phenyl ring mesogen in smectic C phase. In this novel approach, the static 13C NMR spectral data of synthetic mesogenic intermediate namely two-ring aldehyde are utilised for the chemical shift assignment of three-ring mesogens. Further, the orientational order parameter of two-ring aldehyde in smectic A and three-ring mesogen in smectic C phase is carried out by measuring the 13C-1H dipolar couplings by 2D separated local field spectroscopy. 相似文献
144.
Preparation,spectroscopic, thermal and powder X‐ray diffraction characterization,and antimicrobial activities of mixed bis(O,O′‐diisopropyldithiophosphato‐S,S′)antimony(III) derivatives with some oxygen and sulfur donor ligands 下载免费PDF全文
Newly synthesized mixed bis(O,O′‐diisopropyldithiophosphato‐S,S′)antimony(III) derivatives have been characterized using physicochemical, spectral, thermal and powder X‐ray diffraction studies, and their antimicrobial activities were investigated. These derivatives have nanometric crystallite size (11.39–14.67 nm) with unit cell volume (4968.47 and 5079.79 Å3) and lower symmetry (monoclinic) crystal system. After thermal decomposition in inert atmosphere, these derivatives give antimony sulfide as a final decomposition product which has many potential applications, and they exhibit enhanced antimicrobial activities (greater zone of inhibition) as compared to the free ligands and standard drugs (chloroamphenicol and terbinafine were used as standard antibacterial and antifungal drugs, respectively) due to the nanometric size of the complexes. 相似文献
145.
Alassad Mustafa Hussain Muhammad Nihal Agarwal Nitin 《Central European Journal of Operations Research》2022,30(1):367-394
Central European Journal of Operations Research - With the power of social media being harnessed to coordinate events and revolutions across the globe, it is important to identify the key sets of... 相似文献
146.
Sachin V. Bhilare Nitin B. Darvatkar Amol R. Deorukhkar Meghana S. Rasalkar 《合成通讯》2013,43(18):3111-3117
1‐Butyl‐3‐methylimidazolium chloroaluminate, [bmim]Cl·.AlCl3 (molar fraction, N=0.67), ionic liquid has been used in combination with metallic Zn for the reductive coupling of carbonyl compounds to synthesize symmetrical olefins, with the Z‐isomer formed predominantly. The ionic liquid played a dual role of Lewis acid catalyst and solvent. 相似文献
147.
Enantiomerically pure 4-oxo-2-cyclopentenyl derivatives were prepared by kinetic resolution with penicillin G acylase (EC 3.5.1.11) immobilized on an epoxy activated polymer. The enzyme selectively hydrolyzes the phenylacetyl ester of the (S)-enantiomer to give the (S)-alcohol. The enantioselectivity E increases from 12.4 in 0.05 M phosphate buffer, to E = 100–110 in acetonitrile-buffer (20% v/v) and E >200 in diisopropyl ether. The immobilized enzyme is stable and retains >90% of its activity after 10 recycles over one week at room temperature. 相似文献
148.
149.
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
150.
Gowrisankar Reddipalli Mallam Venkataiah Nitin W. Fadnavis 《Tetrahedron: Asymmetry》2011,22(18-19):1778-1783
(?)-α-Conhydrine was synthesized from propargyl alcohol in 20% overall yield in nine steps. The key intermediates were obtained via a regioselective epoxide opening, cross-metathesis, tandem hydrogenation and hydrogenolysis, and stereoselective dihydroxylaton. The side product from the epoxide ring opening was used to synthesize the seven-membered amino sugar DMJ analogue. 相似文献