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91.
The extended Boltzmann equation introduced in previous papers is used to compute the torque exerted on a macroscopic sphere or cylinder placed in a dilute gas, when the mean free path of the gas molecules is small compared to the characteristic dimension of the sphere or cylinder. The usual hydrodynamic results are recovered in this kinetic theory calculation.Work supported in part by the National Science Foundation Grant No. CHE 77-16308. 相似文献
92.
Reactions of propargyl trimethyl silane with ω-ethoxy lactams 1a-c under the influence of boron trifluoride etherate afford ω-allenyl lactams 3a-c; 5-allenyl-2-pyrrolidinone is hydrolysed to γ-allenyl-GABA. 相似文献
93.
We present a transpose-free version of the nonsymmetric scaled Lanczos procedure. It generates the same tridiagonal matrix
as the classical algorithm, using two matrix–vector products per iteration without accessing AT. We apply this algorithm to obtain a transpose-free version of the Quasi-minimal residual method of Freund and Nachtigal
[15] (without look-ahead), which requires three matrix–vector products per iteration. We also present a related transpose-free
version of the bi-conjugate gradients algorithm.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
94.
Jan R. de Dobbelaere Erica L. van Zeeventer Jan W. de Haan Henk M. Buck 《Theoretical chemistry accounts》1975,38(3):241-244
INDO calculations have been performed for the activated complex of the [1, 5] H.-shift in 1,3-cyclohexadiene and 1,3,5-cycloheptatriene. During the migration in the cyclohexadiene system a homoconjugation was calculated between the carbon atoms C1 and C5. For cycloheptatriene it could be demonstrated that one double bond does not participate in the reaction. Activation enthalpies are related to (homo)conjugation in the transition state of the reaction for cyclic conjugated dienes and trienes. The electron density on the migrating hydrogen can be related to the electron affinity of the ring system in the transition state.[/p] 相似文献
95.
Henk Hiemstra Wim J. Klaver Marinus J. Moolenaar W.Nico Speckamp 《Tetrahedron letters》1984,25(47):5453-5456
The combination of a silicon directed N-acyliminium ion cyclization reaction and a subsequent SN2′ substitution of an imide nitrogen with lithium dimethyl cuprate constitutes a novel approach to functionalized transfused carbobicycles. 相似文献
96.
Intramolecular reactions of acyclic N-acyliminium ions with allyl silanes, induced by protic or Lewis acid, lead to 3-vinylpyrrolidines or 3-vinylpiperidines. 相似文献
97.
98.
Biology often uses hierarchical self-assembly to produce complex functional structures from smaller components. At each level of this stepwise process, non-covalent interactions bring together the subunits of a lower level of complexity, using the information encoded in their structures. Applying this approach to synthetic systems represents a formidable challenge, because it requires a high degree of command of non-covalent interactions. In this tutorial review, recent developments in the hierarchical self-assembly of discrete columnar aggregates are discussed. 相似文献
99.
A terpyridine ruthenium (II) complex containing a substituted and an unsubstituted terpyridine ligand was synthesized, and its luminescence properties were studied in a solid-state single-layer light-emitting electrochemical cell. The obtained devices emitted light of a very deep red color (CIE, x = 0.717 y = 0.282) at low external applied bias. It is the first example of an electroluminescence device based on a bis-chelated ruthenium complex. Its ambient atmosphere decay is remarkably different from analogous devices using tris-chelated ruthenium complexes. 相似文献
100.
Kinderman SS Wekking MM van Maarseveen JH Schoemaker HE Hiemstra H Rutjes FP 《The Journal of organic chemistry》2005,70(14):5519-5527
[reaction: see text] Catalytic Sn(OTf)2-induced cyclization of linear, aryl-containing allylic N,O-acetals produced vinyl-substituted tetrahydroisoquinolines and tetrahydro-1H-beta-carbolines. The usefulness of the vinyl moiety in the resulting products was demonstrated via the synthesis of various key building blocks for alkaloid structures. The alpha-vinyl moiety was utilized in a [2,3] sigmatropic rearrangement, in ring-closing metathesis and a cross-metathesis-based synthesis of vincantril, an antianoxia agent, and a synthetic member of the vincamine type natural products. 相似文献