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991.
2,4,6‐Trichloro‐1,3,5‐triazine efficiently catalyzed the condensation reactions between 2‐aminothiophenol and aromatic aldehydes to afford 2‐arylbenzothiazolles in good‐to‐excellent yields. Simple and mild reaction conditions, the use of a cheap catalyst and easy work up, and isolation are notable features of this method. J. Heterocyclic Chem., (2011).  相似文献   
992.
In this paper we first introduce the famous Klein tization approach and taking the negative modes into account densities could be achieved without confronting any paradox. paradox. Afterwards by proposing the Krein quan- , we will show that the expected and exact current  相似文献   
993.
We have studied the charge‐transfer‐induced deactivation of nπ* excited triplet states of benzophenone derivatives by O2(3Σ), and the charge‐transfer‐induced deactivation of O2(1Δg) by ground‐state benzophenone derivatives in CH2Cl2 and CCl4. The rate constants for both processes are described by Marcus electron‐transfer theory, and are compared with the respective data for a series of biphenyl and naphthalene derivatives, the triplet states of which have ππ* configuration. The results demonstrate that deactivation of the locally excited nπ* triplets occurs by local charge‐transfer and non‐charge‐transfer interactions of the oxygen molecule with the ketone carbonyl group. Relatively large intramolecular reorganization energies show that this quenching process involves large geometry changes in the benzophenone molecule, which are related to favorable Franck‐Condon factors for the deactivation of ketone‐oxygen complexes to the ground‐state molecules. This leads to large rate constants in the triplet channel, which are responsible for the low efficiencies of O2(1Δg) formation observed with nπ* excited ketones. Compared with the deactivation of ππ* triplets, the non‐charge‐transfer process is largely enhanced, and charge‐transfer interactions are less important. The deactivation of singlet oxygen by ground‐state benzophenone derivatives proceeds via interactions of O2(1Δg) with the Ph rings.  相似文献   
994.
This study aimed at investigating the impact of early versus normal grain harvesting on the chemical composition and secondary metabolites of Amaranthus cruentus species grown in South Africa. Mature harvested grain had higher (p < 0.05) DM, CF, NDF and ADF content compared to prematurely harvested grain. There were no significant (p > 0.05) differences between CP, ADL and GE of premature and mature harvested grains. Mature harvesting resulted in higher grain Ca, P, Mg and K content. Essential amino acids spectrum and content remained similar regardless of maturity at harvest. The grains displayed an ample amount of unsaturated fatty acids; the highest percentage was linoleic acid: 38.75% and 39.74% in premature and mature grains, respectively. β-Tocotrienol was detected at 5.92 and 9.67 mg/kg in premature and mature grains, respectively. The lowest was δ-tocotrienol which was 0.01 and 0.54 mg/kg in premature and mature grains, respectively. Mature harvested grain had a higher secondary metabolite content compared to premature harvested grains. The results suggest that mature harvested Amaranthus cruentus grain contain more minerals and phytochemicals that have health benefits for human and livestock immunity and gut function, which ultimately improves performance. This study concludes that A. cruentus grown in South Africa is a potential alternative cereal to major conventional cereals.  相似文献   
995.
DSC-measurements show in a simple and convincing manner that the precipitation of the metastableS-phase in an Al-2.1% Cu-1.3% Mg alloy is enhanced in the presence of lattice defects (dislocation loops, helices, dislocations), but is little influenced by pre-existing GPB-zones.
Zusammenfassung DSC-Untersuchungen zeigen auf einfache und überzeugende Weise, da\ die Bildung der metastabilen S-Phase in einer Al-Cu-Mg-Legierung (Al-2.1%, Cu 1.3 %Mg) in Gegenwart von Gitterdefekten (Versetzungsringe, Wendeln, Versetzungen) gesteigert, aber durch vorherige GPB-Zonen nur wenig beeinflu\t wird.


We are greatly indebted to Centre de Recherches de Voreppe S. A. for the preparation of the alloy.  相似文献   
996.
The high-field 1H NMR spectra of 1,3-propanesultams (2), 2,4-butanesultams (3) and 2,4-dimethyl-1,3-butadienesultams (6) are reported. Comparison of 2,3 and 6 with 1,3-propanesultone (1) and 2,4-dimethyl-1,3-butadienesultone (5) reveals that the paramagnetic shift induced by the NH group is smaller than that induced by oxygen. NMR spectra at lower temperature show coupling effects with the NH proton. A half-chair conformation was deduced for 2,4-butanesultam from coupling constants and from a conformational analysis based on the R values, but a chair-chair interconversion could not be detected in the temperature range between 210 and 330 K. An unambiguous assignment was carried out for the methyl signals in the spectrum of 5 by homodecoupling experiments.  相似文献   
997.
The presence of small GP-zones in an Al-3 wt% Zn solid solution aged at temperatures below 80° is inferred from calorimetric reversion studies, although this composition lies outside the miscibility gap of the accepted phase diagram. The size of the zones is about 1 to 1.5 nm, as measured by high resolution electron microscopy.We are greatly indebted to the research staff in the electron microscopy laboratory of C.E.N.G. (Grenoble, France) for the use of a high resolution electron microscope.  相似文献   
998.

Today, plant extracts based on synthetic procedures have drawn consideration over conventional methods like physical and chemical procedures to synthesize nanomaterials. Green synthesis of nanomaterials has become an area of interest because of numerous advantages such as non-hazardous, economical, and feasible methods with a variety of applications in biomedicine, nanotechnology and nano-optoelectronics and as catalysts for various organic transformations. In this research, silver nanoparticles were deposited on the surface of nano-silica spheres by an in-situ reduction of Ag+ ions using an aqueous extract of Thymus kotschyanus aerial parts as a natural reducing and a capping agent. The result recorded from ultraviolet–visible (UV–Vis) spectrometer, Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS) and X-ray powder diffraction supports the biosynthesis and characterization of Ag/SiO2 nanoparticles. The results indicated that the average size of Ag/SiO2 nanoparticles is 25–60 nm. The Ag/SiO2 nanoparticles act as an environmentally friendly heterogeneous catalyst in the synthesis of spirooxindoles via the three-component condensation reaction of isatins, activated methylene reagents, and 1,3-dicarbonyl compounds in aqueous media, and the desired products were obtained with yields ranging from 90 to 98%. The catalyst can be recovered easily and used repetitively without significant loss of catalytic activity.

Graphical abstract
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999.
1000.
11H-Indeno[1,2-b]quinoxalin-11-ones generated in situ from ninhydrin and various 1,2-phenylenediamines, catalysed by montmorillonite K10 under microwave irradiation, condense with 4-hydroxyproline to produce 11-(1H-pyrrol-1-yl)-11H-indeno[1,2-b]quinoxaline derivatives in good yields.  相似文献   
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