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441.
Thomas J. Venanzi Bruce P. Bryant Carol A. Venanzi 《Journal of computer-aided molecular design》1995,9(5):439-447
Summary A model of analogue-receptor binding is developed for the l-alanine receptor in the channel catfish using the AM1-SM2 and ab initio SCRF computational methods. Besides interactions involving the zwitterionic moiety of the amino acid analogue and complementary subsites on the receptor, the model suggests the presence of a hydrophobic pocket with dispersion interactions between the receptor and the residue on the amino acid analogue. Conformational analysis suggests not only a small compact active site on the receptor, but also that the analogues with the highest affinity occupy nearly identical regions of space. Although the binding interaction is dominated by the ionic terms, AM1-SM2 calculations indicate that free energy terms associated with cavity formation, solvent reorganization, and dispersion interactions can be correlated to activation and neural response. From a consideration of this model, molecular features of the analogues that are important for binding and neural response were deduced and other analogues or ligands were developed and tested. 相似文献
442.
Darryn E. Bryant 《Journal of Algebraic Combinatorics》1995,4(3):197-200
Decompositions of the complete graph with n vertices K
n into edge disjoint cycles of length m whose union is K
n are commonly called m-cycle systems. Any m-cycle system gives rise to a groupoid defined on the vertex set of K
n via a well known construction. Here, it is shown that the groupoids arising from all m-cycle systems are precisely the finite members of a variety (of groupoids) for m = 3 and 5 only. 相似文献
443.
Recently the generalized Doyen-Wilson problem of embedding a 5-cycle system of orderu in one of orderv was completely solved. However it is often useful to solve the more general problem of the existence of a 5-cycle system of orderv with a hole of sizeu. In this paper we completely solve this problem.Dedicated to Hanfried Lenz on the occasion of his 80th birthdayResearch supported by NSF grant DMS 9225046 相似文献
444.
利用离子注入技术制备ZnS发光二极管,当激发参数改变时,电致发光给出不同的发射颜色。一种类型ZnS发光二极管是将Nd离子注入到ZnS的一个表面,而Er离子注入到另一个表面,两而的电极做成条状并彼此交错,仪当反向偏压时才给出电致发光,因而外加电压改变极性时,二极管将是绿色(Er3+)或橙色(Nd3+)发光。第二种类型ZnS发光二极管是将Er和Nd离子注入到ZnS的同一表面,但是不同的深度,当外加电压的大小改变时,二极管发光颜色可以从绿色到橙色或者从橙色到绿色。 相似文献
445.
446.
H.C. Bryant A.A. Carter M. Coupland E. Eisenhandler W.R. Gibson P.I.P. Kalmus T.W. Pritchard H. Sandhu S.J. Watts G.T.J. Arnison A. Astbury J.K. Davies G.H. Grayer D. Hill A.W. Robertson T.P. Shah C. Sutton 《Nuclear Physics B》1980,168(2):207-221
The polarization parameter has been measured for K?p elastic scattering at nine incident beam momenta between 0.955 and 1.272 GeV/c covering the c.m. angular range . Experimental results and coefficients of Legendre polynomial fits to the data are presented and compared with other measurements and a partial-wave analysis. 相似文献
447.
在真空中用共蒸发方法制的直流电致发光薄膜ZnS:Cu,Nd,Cl,实验中测量了它的可见和红外发射。本文研究了Nd3+离子的各个激发态的寿命各个辐射波长的发射强度与温度和外加电压的关系,发现导带中参与电致发光激发过程的热电子能量分布遵从玻尔兹曼函数,热电子平均能量是0.16eV左右,这个值和能量转换效率测量结果相一致。 相似文献
448.
449.
Robert D. Bryant Fen-Ann Kunng Michael S. South 《Journal of heterocyclic chemistry》1995,32(5):1473-1476
A large scale synthesis of 3-chloro-5-methoxypyridazine was developed (18 moles) that relies on the protection of the pyridazinone nitrogen of 4,5-dichloro-3(2H)-pyridazinone as the tetrahydropyranyl derivative 2 . The 5-chloro position of the protected pyridazinone was selectively displaced with methoxide to give 3 followed by catalytic hydrogenation of the 4-chloro group to give 4. Removal of the protecting group with acid followed by phosphorous oxychloride treatment gave the target compound 6 in good yield. This route is superior to the previously described synthesis of this compound. 相似文献
450.
Hernández G Teng CL Bryant RG LeMaster DM 《Journal of the American Chemical Society》2002,124(16):4463-4472
Paramagnetically induced relaxation effects of O2 and the nitroxide 4-hydroxy TEMPO were measured for the amide protons of perdeuterated rubredoxin from the hyperthermophilic archaeon Pyrococcus furiosus and the mesophilic bacterium Clostridium pasteurianum. For both O2 and the impermeant nitroxide, the induced relaxation at the static solvent inaccessible amide sites is dominated by long-range interactions with the paramagnetic species in the bulk aqueous phase. The upper bound of O2 solubility in the internal matrix of the rubredoxins is one-tenth that of the bulk aqueous phase. Furthermore, the difference between the oxygen solubilities inside the two rubredoxins is at most 1% that of bulk water O2 solubility, suggesting that there are only modest differences in this measure of fluidity for the mesophile vs hyperthermophile protein interiors. Calculations based on the assumption of a paramagnet uniformly distributed on the protein exterior yield accurate predictions at nearly all amide sites for the minimum relaxation value observed from either the O2 or nitroxide data. Model calculations indicate that the readily obtained paramagnetically induced relaxation effects should prove effective in recognition of structural homology for proteins that are too widely diverged for sequence-based recognition. 相似文献