Results 171 to 180 of about 3,034,026 (343)

Generic regular universes in higher order gravity theories [PDF]

arXiv, 2013
We review recent results on the Cauchy-Kowalevsky structure of theories with higher derivatives in vacuum. We prove genericity of regularity of solutions under the assumption of analyticity. Our approach is framed in the general context of formal series expansions of the metric around a regular point.
arxiv  

Reactions of Spiro[2.6]nona-4,6,8-triene Derivatives with Acids and Bases. Rearrangement to a Heptafulvene Derivative and Formation of Ether Linkage Compounds [PDF]

, 1979
Takashi Toda, Katsuhiro Saito, Toshio Mukai   +2 more
openalex   +1 more source

Studies on Spiroheterocyclic Nitrogen Compounds. Part 1 : Synthesis of Some New Spiro Pyrazolines, Isoxazolines and Pyrimidinethiones Containing Benzanilide Moiety [PDF]

, 1984
B. E. BAYOUMY, SAID EL BAHAIE, A. E. ABDEL RAHMAN   +2 more
openalex   +1 more source

Synthesis, Molecular Docking Study, Anti-Oxidant and Cytotoxicity Evaluation of New Spiro Six Membered Ring Derivatives of 5-nitro isatin

Iraqi Journal of Pharmaceutical Sciences
Spiro-5-nitro isatino six memberd ring (quinazoline-4-one, thiazine-4-one and oxazine-4-one) respectively were produced by a cycloaddition of 5-nitro isatin Schiff bases [1–5] with anthranilic acid, o-mercapto benzoic acid and salicylic acid.
Hala Ayad Mohamed Rasheed, Suaad M. H. Al-Majidi   +1 more
doaj   +1 more source

Synthesis of Functionalized Spiro-Heterocycles by Sequential Multicomponent Reaction/Metal Catalyzed Carbocylizations from Simple β-Ketoesters and Amides

, 2007
International audienceA new strategy from simple cyclic β-ketoesters or amides involving a selective three-component reaction and a ring closing metathesis or a palladium catalyzed carbocyclization in a sequential fashion to access spiro-heterocycles is ...
Habib-Zahmani, Hadjira, Rodriguez, Jean, Viala, Jacques   +2 more
core   +3 more sources

α‐Amination of 1,3‐Dicarbonyl Compounds and Analogous Reactive Enolate‐Precursors Using Ammonia under Oxidative Conditions

Angewandte Chemie International Edition, EarlyView.
Using ammonia in combination with hypochlorites as simple oxidants under phase‐transfer conditions allows for the direct oxidative α‐amination of reactive enolate precursors such as cyclic β‐ketoesters, oxindoles, as well as malonitriles and malonates with good to excellent yields.
Christopher Mairhofer, Katharina Röser, Gabriel Burel, Sarah Merzinger, Jean‐François Brière, Roland Obermüller, Mario Waser   +6 more
wiley   +1 more source

Influence of Ligand Design and Non‐Covalent Interactions on the Isoselective Ring‐Opening Polymerization of rac‐β‐Butyrolactone Using Salan and Salalen Rare‐Earth Metal Catalysts

Angewandte Chemie International Edition, EarlyView.
Polyhydroxybutyrates are key sustainable polyesters, but controlling the stereoregularity is crucial for exhibiting the most promising thermal and mechanical properties. Highly active rare‐earth metal salan/salalen complexes yield isotactic (Pm up to 0.96 at 0 °C) or syndioenriched (Pr up to 0.91) PHB, depending on the steric demand of the ligand and ...
Stefanie Hörl, Ion Chiorescu, Jonas Bruckmoser, Jonas Futter, Bernhard Rieger   +4 more
wiley   +1 more source

DIASTEREOS ELECTIVE SYNTHESIS OF BRIDGEHEAD HETEROBICYCLIC SPIRO COMPOUNDS DERIVED FROM TANDEM MICHAEL INTRAMOLECULAR 1,3-DIPOLAR CYCLOADDITION OF NITRONES [PDF]

, 2000
Md. Jashim Uddin, Tetsuya Fujimoto, Akikazu Kakehi, Hirofusa Shirai, Iwao Yamamoto   +4 more
openalex   +1 more source

STUDIES ON SPIROHETEROCYCLES : SYNTHESIS OF NEW SPIRO 4- THIAZOLIDINONES AS POSSIBLE BIODYNAMICS [PDF]

Journal of Sciences, Islamic Republic of Iran, 1992
Spiro-4- thiazolidinones have been synthesized by the cyclocondensation of phthalazinyl hydrazones with cyclic ketones and substituted mercapto acetic acids. Compounds were screened for their antibacterial, antifungal and antihypertensive activity.
doaj  

Human interparietal bones: Examination of existing classification schemes and development of a graphic library depicting variations

The Anatomical Record, EarlyView.
Examples from the graphic library depicting morphologies of interparietal bones, ossicles at lambda, mendosal sutures, and intrasutural ossicles. Abstract Due to its complex ossification during development, the superior region of the human occipital bone is a frequent site of supernumerary bones known as interparietal bones.
Melissa D. Clarkson, Rhian R. Dunn, Joseph T. Hefner, Holly A. Long, Micayla C. Spiros   +4 more
wiley   +1 more source