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The control of piecewise-deterministic processes is studied where only local boundedness of the data is assumed. Moreover the discount rate may be zero. The value function is shown to be solution to the Bellman equation in a weak sense; however the solution concept is strong enough to generate optimal policies. Continuity and compactness conditions are given for the existence of nonrelaxed optimal feedback controls. 相似文献
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Terminal alkynes undergo mild and efficient aminomethylation with aqueous formaldehyde and secondary amines under CuI catalysis. In most cases high to nearly quantitative yields of tertiary propargylamines are obtained in DMSO solution at room temperature. Aromatic, aliphatic and silylated acetylenes as well as alkynols can be used. Primary amines are less reactive and satisfactory yields of secondary propargylamines are obtained only with phenylacetylene. 相似文献
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Synthesis and Crystal Structure Determination of Lead(II) Oxide Halide Alcoholates with Different Connectivity of Pb4O4 Heterocubane‐like Subunits The reaction of red lead(II) oxide (Litharge) and lead(II) halide (Cl? and Br?) with diethylene glycole at a temperature of 180 °C leads to the isotypic compounds [Pb6(C4H8O3)O2Cl6] (1) and [Pb6(C4H8O3)O2Br6] (2) . In a similar synthesis with PbI2 as educt at temperature of 160 °C the two modifications β‐[Pb6(C4H8O3)O2I6] (3) and α‐[Pb6(C4H8O3)O2I6] (4) were found, whereas at a reaction temperature of 180 °C [Pb9(C2H4O2)(C4H8O3)O3I8] (5) was surprisingly obtained as product. The X‐ray diffraction data show that at a temperature of 180 °C a splitting of the ether took place. The cited compounds show cubane like subunits built by lead and oxygen atoms. These fragments are connected by alkoholate molecules. In 5 additionally an I6 octahedra centered by lead is observed. 相似文献
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Yu JQ Wu HC Ramarao C Spencer JB Ley SV 《Chemical communications (Cambridge, England)》2003,(6):678-679
A robust and recyclable palladium catalyst [Pd0EnCat] has been prepared by ligand exchange of polyurea-encapsulated palladium(II) acetate with formic acid, resulting in deposition of Pd(0) in the support material; Pd0EnCat is shown to be a highly efficient transfer hydrogenation catalyst for chemoselective reduction of a wide range of aryl ketones to benzyl alcohols. 相似文献