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101.
Waldemar Adam Hector Rebollo Heinz Dürr Karl-Heinz Pauly Karl Peters Eva-Maria Peters Hans-Georg von Schnering 《Tetrahedron letters》1982,23(9):923-926
4-Methyl-1,2,4-triazoline-3,5-dione (MTAD) gives with 7-spiro-fluorenyl-1,3,5-cycloheptatriene () initially he norcaradine-type urazole () which at ambient temperatures rearranges into (), while 102 gives the tropilidene-type endoperoxide (). 相似文献
102.
Stowers MA van Wuijckhuijse AL Marijnissen JC Scarlett B van Baar BL Kientz CE 《Rapid communications in mass spectrometry : RCM》2000,14(10):829-833
Matrix-assisted laser desorption/ionization (MALDI) mass spectra were obtained from single biological aerosol particles using an aerosol time-of-flight mass spectrometer (ATOFMS). The inlet to the ATOFMS was coupled with an evaporation/condensation flow cell that allowed the aerosol to be coated with matrix material as the sampled stream entered the spectrometer. Mass spectra were generated from aerosol composed either of gramicidin-S or erythromycin, two small biological molecules, or from aerosolised spores of Bacillus subtilis var niger. Three different matrices were used: 3-nitrobenzyl alcohol, picolinic acid and sinapinic acid. A spectrum of gramicidin-S was generated from approximately 250 attomoles of material using a molar ratio of 3-nitrobenzyl alcohol to analyte of approximately 20:1. A single peak, located at 1224 Da, was obtained from the bacterial spores. The washing liquid and extract solution from the spores were analyzed using electrospray mass spectrometry and subsequent MS/MS product ion experiments. This independent analysis suggests that the measured species represents part of the B. subtilis peptidoglycan. The on-line addition of matrix allows quasi-real-time chemical analysis of individual, aerodynamically sized particles, with an overall system residence time of less than 5 seconds. These results suggest that a MALDI-ATOFMS can provide nearly real-time identification of biological aerosols. Copyright 2000 John Wiley & Sons, Ltd. 相似文献
103.
Eduardo Dfaz Hector Barrios Jose Luis Nava Raul G. Enriquez Angel Guzmn Len G. Leticia Jose Fernando Fuentes Fuentes B. Aidee Angelina Quintero Jose Dolores Solano 《Journal of heterocyclic chemistry》1997,34(3):1037-1041
The Stereoselective addition of the pyrimidine derivative 1 to the exocyclic methylene of the α,β unsaturated dehydrocostus lactone 2, Ivalin acetate 3 and Zaluzanin A diacetate 4, was achieved resulting in a new C-C bond formation. In the cases of compounds 3 and 4, after the addition, the lactone was cleaved followed by reclosure into a lactam ring system. 相似文献
104.
Choi M Yamamoto K Itoh T Makishima M Mangelsdorf DJ Moras D DeLuca HF Yamada S 《Chemistry & biology》2003,10(3):261-270
We present a new method to investigate the details of interaction between vitamin D nuclear receptor (VDR) and various ligands, namely a two-dimensional alanine scanning mutational analysis. In this method, the transactivation of various ligands is studied in conjunction with a series of alanine scanning mutations of the residues lining the ligand binding pocket (LBP) of VDR, and the complete set of results is profiled in a patch table. We investigated examples from four structurally diverse groups of known VDR ligands: the native vitamin D hormone and two compounds with the same side chain configuration; four 20-epi compounds; three 19-nor compounds; and two nonsecosteroids. The patch table of the results indicates characteristics of each group in terms of its interaction with 18 LBP residues. We demonstrate the validity of this approach by application to docking studies of the two nonsecosteroids. 相似文献
105.
Hebah Muhsien Sabiah AL Ubeed Deep Jyoti Bhuyan Muhammad A. Alsherbiny Amrita Basu Quan V. Vuong 《Molecules (Basel, Switzerland)》2022,27(3)
Cannabis is well-known for its numerous therapeutic activities, as demonstrated in pre-clinical and clinical studies primarily due to its bioactive compounds. The Cannabis industry is rapidly growing; therefore, product development and extraction methods have become crucial aspects of Cannabis research. The evaluation of the current extraction methods implemented in the Cannabis industry and scientific literature to produce consistent, reliable, and potent medicinal Cannabis extracts is prudent. Furthermore, these processes must be subjected to higher levels of scientific stringency, as Cannabis has been increasingly used for various ailments, and the Cannabis industry is receiving acceptance in different countries. We comprehensively analysed the current literature and drew a critical summary of the extraction methods implemented thus far to recover bioactive compounds from medicinal Cannabis. Moreover, this review outlines the major bioactive compounds in Cannabis, discusses critical factors affecting extraction yields, and proposes future considerations for the effective extraction of bioactive compounds from Cannabis. Overall, research on medicinal marijuana is limited, with most reports on the industrial hemp variety of Cannabis or pure isolates. We also propose the development of sustainable Cannabis extraction methods through the implementation of mathematical prediction models in future studies. 相似文献
106.
107.
Max Chacn Hector Rojas-Pescio Sergio Pealoza Jean Landerretche 《Entropy (Basel, Switzerland)》2022,24(3)
The mechanism of cerebral blood flow autoregulation can be of great importance in diagnosing and controlling a diversity of cerebrovascular pathologies such as vascular dementia, brain injury, and neurodegenerative diseases. To assess it, there are several methods that use changing postures, such as sit-stand or squat-stand maneuvers. However, the evaluation of the dynamic cerebral blood flow autoregulation (dCA) in these postures has not been adequately studied using more complex models, such as non-linear ones. Moreover, dCA can be considered part of a more complex mechanism called cerebral hemodynamics, where others (CO2 reactivity and neurovascular-coupling) that affect cerebral blood flow (BF) are included. In this work, we analyzed postural influences using non-linear machine learning models of dCA and studied characteristics of cerebral hemodynamics under statistical complexity using eighteen young adult subjects, aged 27 ± 6.29 years, who took the systemic or arterial blood pressure (BP) and cerebral blood flow velocity (BFV) for five minutes in three different postures: stand, sit, and lay. With models of a Support Vector Machine (SVM) through time, we used an AutoRegulatory Index (ARI) to compare the dCA in different postures. Using wavelet entropy, we estimated the statistical complexity of BFV for three postures. Repeated measures ANOVA showed that only the complexity of lay-sit had significant differences. 相似文献
108.
Hector Puebla Roland Martin Jose Alvarez-Ramirez Ricardo Aguilar-Lopez 《Chaos, solitons, and fractals》2009,39(2):971-980
A new feedback control method is proposed to control the spatio-temporal dynamics in excitable media. Applying suitable external forcing to the system’s slow variable, successful suppression and control of propagating pulses as well as spiral waves can be obtained. The proposed controller is composed by an observer to infer uncertain terms such as diffusive transport and kinetic rates, and an inverse-dynamics feedback function. Numerical simulations shown the effectiveness of the proposed feedback control approach. 相似文献
109.
Asymplectic integration of a Poisson manifold (M, Λ) is a symplectic groupoid (Γ,η) whichrealizes the given Poisson manifold, i.e. such that the space of units Γ0 with the induced Poisson structure Λ0 is isomorphic to (M, Λ). This notion was introduced by A. Weinstein in [28] in order to quantize Poisson manifolds by quantizing their symplectic
integration. Any Poisson manifold can be integrated by alocal symplectic groupoid ([4], [13]) but already for regular Poisson manifolds there are obstructions to global integrability
([2], [6], [11], [17], [28]).
The aim of this paper is to summarize all the known obstructions and present a sufficient topological condition for integrability
of regular Poisson manifolds; we will indeed describe a concrete procedure for this integration. Further our criterion will
provide necessary and sufficient if we require Γ to be Hausdorff, which is a suitable condition to proceed to Weinstein’s
program of quantization. These integrability results may be interpreted as a generalization of the Cartan-Smith proof of Lie’s
third theorem in the infinite dimensional case.
Recherche supportée par D.G.I.C.Y.T. Espagne (Proyecto PB90-0765) et Xunta de Galicia (Proxecto XUGA20704B90) 相似文献
Recherche supportée par D.G.I.C.Y.T. Espagne (Proyecto PB90-0765) et Xunta de Galicia (Proxecto XUGA20704B90) 相似文献
110.