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排序方式: 共有329条查询结果,搜索用时 15 毫秒
91.
A mechanism is suggested to explain the information processing abilities of simple natural brains, which, by experimental evidence, display behavior like chaotic dynamical systems while at rest. The Lorenz system of equations is dealt with as a case study, and a comparison of the suggested mechanism with the standard theory of neural networks is made. 相似文献
92.
Chau Hon Ho Erich Odermatt Ingo Berndt Joerg C. Tiller 《Journal of polymer science. Part A, Polymer chemistry》2008,46(15):5053-5063
Polylysines (PL) are highly interesting polymers due to their biocompatibility and their high number of reactive amino groups. So far it was not possible to synthesize them directly from L ‐lysine. Here, we describe two different synthesis routes to selectively polymerize lysine in one batch without the use of protection groups. Applying 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide as activating agent for the polycondensation of L ‐lysine in water gave selectively linear ε‐PLL. In contrast to this, the polymerization of L ‐lysine in chloroform in the presence of dicyclohexyl carbodiimide and 18‐crown‐6 ether selectively afforded pure α‐PLL. We also assessed the capability of polylysine derivatization by polymer analog reactions with acetic anhydride, methyl iodide and 2,4,6‐trinitrobenzenesulfonic acid. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5053–5063, 2008 相似文献
93.
Extensive plastic deformation of titanium aluminum carbonitride/amorphous carbon nanocomposite coating at room temperature was observed in this study. Nanoindentation measurement showed that the coating hardness was 24.4 GPa with the plasticity of 57.6%. The critical load of 1.3 m coating in scratch test was beyond 100 N. The depth of the 100 N scratch track identified by microstylus profilometer was 6.7 m, while the thickness of the coating in the center of the scratch track observed by scanning electron microscopy was 0.4 m, which is only about one third of that for the as-deposited coating. The amorphous carbon with sp2 hybrid and -bonding is proposed to account for this unique plasticity. PACS 81.15.Gh; 81.07.Bc 相似文献
94.
Giora Hon 《Physics in Perspective (PIP)》2003,5(2):150-173
95.
N. -S. Hon 《Colloid and polymer science》1978,256(7):710
Ohne Zusammenfassung 相似文献
96.
Lee HM Olmstead MM Suetsuna T Shimotani H Dragoe N Cross RJ Kitazawa K Balch AL 《Chemical communications (Cambridge, England)》2002,(13):1352-1353
A sample of C60 containing ca. 9% Kr@C60 has been used to form crystalline (0.09Kr@C60/0.91C60).(NiII(OEP)).2C6H6 whose X-ray crystal structure reveals that the Kr atom is centered within the carbon cage and does not produce a detectable change in the size of the fullerene. 相似文献
97.
N R Skrynnikov F A Mulder B Hon F W Dahlquist L E Kay 《Journal of the American Chemical Society》2001,123(19):4556-4566
A relaxation dispersion-based NMR experiment is presented for the measurement and quantitation of micros-ms dynamic processes at methyl side-chain positions in proteins. The experiment measures the exchange contribution to the 13C line widths of methyl groups using a constant-time CPMG scheme. The effects of cross-correlated spin relaxation between dipole-dipole and dipole-CSA interactions as well as the effects of scalar coupling responsible for mixing of magnetization modes during the course of the experiment have been investigated in detail both theoretically and through simulations. It is shown that the complex relaxation properties of the methyl spin system do not complicate extraction of accurate exchange parameters as long as care is taken to ensure that appropriate magnetization modes are interchanged in the middle of the constant-time CPMG period. An application involving the measurement of relaxation dispersion profiles of methionine residues in a Leu99Ala substitution of T4 lysozyme is presented. All of the methionine residues are sensitive to an exchange event with a rate on the order of 1200 s(-1) at 20 degrees C that may be linked to a process in which hydrophobic ligands are able to rapidly bind to the cavity that is present in this mutant. 相似文献
98.
Based on the idea of kriging and the radial basis function approximation, we develop in this paper a numerical scheme to integrate harmonic functions with restricted sampling data. To be more precise, the integration is performed by using the function values which are given as discrete sampling data on only part of the boundary. These problems often arise from non-destructive evaluation techniques in the engineering industry. The existence and uniqueness of the solution and the error estimation for the proposed numerical scheme are also discussed. Several numerical experimental results are presented for the verification on the accuracy and convergence of the method. 相似文献
99.
David J. Burns Hon Wai Lam 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(37):10089-10093
1,3‐Enynes containing allylic hydrogens cis to the alkyne are shown to act as one‐carbon partners, rather than two‐carbon partners, in various rhodium‐catalyzed oxidative annulations. The mechanism of these unexpected transformations is proposed to occur through double C H activation, involving a hitherto rare example of the 1,4‐migration of a RhIII species. This phenomenon is general across a variety of substrates, and provides a diverse range of heterocyclic products. 相似文献
100.