排序方式: 共有57条查询结果,搜索用时 0 毫秒
31.
Xiao‐Jing Wei Irini Abdiaj Carlo Sambiagio Chenfei Li Eli Zysman‐Colman Jesús Alczar Timothy Noël 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(37):13164-13168
A continuous‐flow, visible‐light‐promoted method has been developed to overcome the limitations of iron‐catalyzed Kumada–Corriu cross‐coupling reactions. A variety of strongly electron rich aryl chlorides, previously hardly reactive, could be efficiently coupled with aliphatic Grignard reagents at room temperature in high yields and within a few minutes’ residence time, considerably enhancing the applicability of this iron‐catalyzed reaction. The robustness of this protocol was demonstrated on a multigram scale, thus providing the potential for future pharmaceutical application. 相似文献
32.
33.
Rumyana Simeonova Dimitrina Zheleva Iva Valkova Georgi Stavrakov Irena Philipova Mariyana Atanasova Irini Doytchinova 《Molecules (Basel, Switzerland)》2021,26(7)
The acetylcholinesterase (AChE) inhibitors are the main drugs for symptomatic treatment of neurodegenerative disorders like Alzheimer’s disease. A recently designed, synthesized and tested hybrid compound between the AChE inhibitor galantamine (GAL) and the antioxidant polyphenol curcumin (CU) showed high AChE inhibition in vitro. Here, we describe tests for acute and short-term toxicity in mice as well as antioxidant tests on brain homogenates measured the levels of malondialdehide (MDA) and glutathione (GSH) and in vitro DPPH, ABTS, FRAP and LPO inhibition assays. Hematological and serum biochemical analyses were also performed. In the acute toxicity tests, the novel AChE inhibitor given orally in mice showed LD50 of 49 mg/kg. The short-term administration of 2.5 and 5 mg/kg did not show toxicity. In the ex vivo tests, the GAL-CU hybrid performed better than GAL and CU themselves; in a dose of 5 mg/kg, it demonstrates 25% reduction in AChE activity, as well as a 28% and 73% increase in the levels of MDA and GSH, respectively. No significant changes in blood biochemical data were observed. The antioxidant activity of 4b measured ex vivo was proven in the in vitro tests. In the ABTS assay, 4b showed radical scavenging activity 10 times higher than the positive control butylhydroxy toluol (BHT). The GAL-CU hybrid is a novel non-toxic AChE inhibitor with high antioxidant activity which makes it a prospective multitarget drug candidate for treatment of neurodegenerative disorders. 相似文献
34.
[structure: see text]. We report a new methodology for the construction of novel and uniquely shaped 3-azabicyclo[4.2.0]octan-4-one derivatives by combining the Ugi multicomponent reaction with [2+2] enone-olefin photochemical transformations. The overall sequence is capable of creating up to five stereocenters; however, in most cases, only two diastereomers are observed. 相似文献
35.
Eliass Zafati Michaël Brun Irini Djeran-Maigre Florent Prunier 《Comptes Rendus Mecanique》2014,342(9):539-557
Variant techniques are proposed for reproducing the elastic wave propagation in an unbounded medium such as the infinite elements, the absorbing boundary conditions or the perfect matched layers. Here, a simplified approach is adopted by considering absorbing layers characterized by the viscous Rayleigh matrix as studied by Semblat et al. [16] and Rajagopal et al. [14]. Here, further improvements to this procedure are provided. First, we start by establishing the strong form for the elastic wave propagation in a medium characterized by the Rayleigh matrix. This strong form will be used for deriving optimal conditions for damping out in the most efficient way the incident waves while minimizing the spurious reflected waves at the interface between the domain of interest and the Rayleigh damping layer. A procedure for designing the absorbing layer is proposed by targeting a performance criterion expressed in terms of logarithmic decrement of the wave amplitude in the layer thickness. Second, the GC subdomain coupling method, proposed by Combescure and Gravouil [9], is introduced for enabling the choice of any Newmark time integration schemes associated with different time steps depending on subdomains. When wave propagation is predicted by an explicit time integrator, the subdomain strategy is of great interest because it enables a different time integrator for the absorbing layer to be adopted. An external coupling software, based on the GC method, is used to carry out multi=time step explicit/implicit co-computations, making interact in time an explicit FE code (Europlexus) for the domain of interest, with an implicit FE code (Cast3m) handling the absorbing boundary layers. The efficiency of the approach is shown in 1D and 2D elastic wave propagation problems. 相似文献
36.
A mathematical model is worked out for analyzing propagation ability and the specific energy of horizontally polarized shear surface waves (SH-waves) in multilayered plates. All the layers are assumed to have monoclinic symmetry. Different types of boundary conditions imposed on the outer surfaces of plates are considered. Analytic solutions for one- and two-layered plates are presented. 相似文献
37.
Irini Akritopoulou-Zanze Ying Wang Hongyu Zhao Stevan W. Djuric 《Tetrahedron letters》2009,50(42):5773-5776
The synthesis of all four regioisomers of fused pyrrolidino-pyridines in a one-pot two-step sequential Ugi-inverse electron demand Diels–Alder reaction is described. Fused pyrrolidino-pyrazines, pyrrolidino-pyrimidines and azepinone pyridines can also be obtained in consecutive synthetic sequences. 相似文献
38.
Irini Dimitriyadis 《European Journal of Operational Research》1983,13(4):415-416
39.
40.
It is proved that if the probabilityP is normalised Lebesgue measure on one of thel
p
n
balls in R
n
, then for any sequencet
1
, t
2
, …, t
n
of positive numbers, the coordinate slabs {|x
i
|≤t
i
} are subindependent, namely,
. A consequence of this result is that the proportion of the volume of thel
1
n
ball which is inside the cube[−1, t]
n
is less than or equal tof
n
(t)=(1−(1−t)
n
)
n
. It turns out that this estimate is remarkably accurate over most of the range of values oft. A reverse inequality, demonstrating this, is the second major result of the article.
Supported in part by NSF DMS-9257020.
Supported by a grant from Public Benefit Foundation Alexander S. Onassis. This work will form part of a Ph.D. thesis written
by the second-named author. 相似文献