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排序方式: 共有2376条查询结果,搜索用时 671 毫秒
971.
It is proved that the integral is additive on simple summable functions of a generalized measure space. 相似文献
972.
973.
Garci´a-Lozano Julia Server-Carrio´ Juan Molla M. Carmen Escriva` Emilio 《Transition Metal Chemistry》1997,22(2):161-163
The crystal and molecular structures of [Mn(mep)2- (NCS)2] ({ {mep}}=4-methoxy-2-(5-methoxy-3-methyl-1H-pyrazol-1-yl)-6-methylpyrimidine) have been determined by X-ray crystallography. The crystal structure of the title compound is built up of isolated [Mn(mep)2(NCS)2] molecules with the stereochemistry of a distorted octahedron for the MnN6 chromophore. The e.p.r. (Q-band) data are in agreement with the structural data. 相似文献
974.
Identified π±,K
±, p and -p transverse momentum spectra at mid-rapidity in √sNN = 130 GeV Au-Au collisions were measured by the PHENIX experiment at RHIC as a function of collision centrality. Average
transverse momenta increase with the number of participating nucleonsN
part similarly for all particle species. The multiplicity densities scale faster thanN
part. TheK
± andp
±yields per participant increase faster than the π± yields. We combine the PHENIX neutral and charged pion measurement and find that in central collisions forp
T >-2 GeV/c,-p andp yields are comparable to or even exceed the pion yields. 相似文献
975.
976.
A general continuous review production planning problem with stochastic demand is considered. Conditions under which the stochastic problem may be correctly solved using an equivalent deterministic problem are developed. This deterministic problem is known to have the same solution as the stochastic problem. Moreover, conditions are established under which the deterministic equivalent problem differs from a commonly used deterministic approximation to the problem only in the interest rate used in discounting. Thus, solving the stochastic problem is no more difficult than solving a commonly used approximation of the problem. 相似文献
977.
The factors governing the competitiun between 1,2-and 1,3-eliminations have been studied and the results obtained have been applied to a biomimetic synthesis of chrysanthemol. 相似文献
978.
979.
980.
A facile two-step stereospecific synthesis of the protein farnesyltransferase inhibitor chaetomellic acid A (1) and its analogues was developed. Addition of organocuprates derived from Grignard reagents (e.g. tetradecylmagnesium chloride and CuBr.Me(2)S) to dimethyl acetylenedicarboxylate (DMAD) in tetrahydrofuran containing hexamethylphosphoramide was followed by capture of the resulting copper enolates with a variety of electrophiles (e.g. methyl iodide) to give dimethyl cis-butenedioate derivatives 4-11. Hydrolysis with lithium hydroxide generated the corresponding lithium carboxylates, which readily closed to 2,3-disubstituted maleic anhydrides 17-20 upon acid treatment. Compound 16, an analogue wherein the tetradecyl group of 1 is replaced by a farnesyl moiety, is 7-fold more potent than 1 as an inhibitor of protein farnesyltransferase from yeast and displays a 100:1 selectivity for this enzyme relative to yeast protein geranylgeranyltransferase. In contrast, analogue 15, which contains a geranylgeranyl side chain, shows ca. 10:1 selectivity for the latter enzyme. 相似文献