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71.
72.
The adsorption of well-characterized comb-branched polystyrene onto a chrome plate from cyclohexane solution at the θ temperature has been studied by ellipsometry. Both the adsorbance of the polymer and the extension of the adsorbed layer are compared with values for the linear polystyrene of the same molecular mass. The adsorbance is higher than that of the linear polystyrene, whereas the extension of the adsorbed layer is smaller, reflecting the higher segment density of the branched polymer. The extension tb of the branched polymer is given approximately tb = tlg, where tl is the extension of linear polystyrene of the same molecular mass and g is the ratio of the radii of gyration of the branched and linear polymers. The ratio of the adsorbances Ab/Al of branched and linear polymer is approximately equal to g. These results indicate that the comb-branched polymer is adsorbed as a slightly distorted randam coil with extension and adsorbance governed primarily by the experimental gs factor. 相似文献
73.
74.
Masakatsu Saeki Masami Nakada Nobuyuki M. Masaki Zenko Yoshida Kazutoyo Endo Yoshitaka Minai Toshiyuki Yamashita Hiroshi Mutoh Masaaki Magara 《Hyperfine Interactions》1994,92(1):1177-1181
Experiments on the57Fe Mössbauer effect in frozen solutions were carried out in order to demonstrate the capabilities of a cryostat which was developed for the emission Mössbauer spectroscopy of237Np. We confirmed the existence of an aliovalent state of57Fe in the temperature range from 5.5 to 35 K. However, the relative amounts of Fe(II) and Fe(III) in the frozen matrix were almost constant for the temperature range from 5.5 to 150 K. The design, operation and capabilities of the cryostat are also described. 相似文献
75.
Shinji Funayama Masami Ishibashi Yumi Anraku Kanki Komiyama Satoshi
mura 《Tetrahedron letters》1989,30(52):7427-7430
Structures of novel citocydal antibiotics furaquinocins A and B, isolated from the fermentation broth of Streptomyces sp. KO-3988, was elucidated on the basis of spectroscopic analyses. 相似文献
76.
Katsuyuki Ogura Kazuo Ohtsuki Masami Nakamura Nobuhiro Yahata Kazumasa Takahashi Hirotada Iida 《Tetrahedron letters》1985,26(20):2455-2458
Methylthiomethyl p-tolyl sulfone (1) was conveniently alkylated to give mono- and dialkylated products (2 and 4). Reaction conditions for the trasformation of 2 and 4 into aldehydes (3) and ketones (5), respectively, were exploited. 相似文献
77.
Photolysis of acyclic monothioimides gave β-lactams and thioamides via Type II reaction involving γ-hydrogen abstraction by thiocarbonyl group. 相似文献
78.
Asymmetric conjugate addition of dialkylzinc to alpha,beta-unsaturated N-2,4,6-triisopropylphenylsulfonylaldimines 9 was catalyzed by 5 mol % N-Boc-L-valine-connected amidophosphane 5a-Cu(MeCN)(4)BF(4) in the presence of 4 angstroms MS in toluene to afford, after hydrolysis of an imine to an aldehyde through a short alumina column and reduction with sodium borohydride, the corresponding beta-alkylated alkanols 10 with 67-91% ee in reasonably high yields. 相似文献
79.
Masami Hasegawa Masaharu Tanemura 《Annals of the Institute of Statistical Mathematics》1976,28(1):509-519
Summary In this paper the tesselation of territories is discussed. When a mass of animals with teritoriality is introduced at random
simultaneously into a finite two-dimensional (2D) region, territories are gradually formed and finally settle to a steady
state. A model calculation for this process is carried out, where a Voronoi polygon is assumed as a territory. Comparisons
are made between the model calculation and Barlow's observation on an artificial population of mouthbreeder fish. Differences
between 1D and 2D case are also discussed.
The Institute of Statistical Mathematics 相似文献
80.
Most national curricula for both primary and secondary grades encourage the active involvement of learners through the manipulation of materials (either concrete models or dynamic instruments). This trend is rooted in the emphasis given, at the dawn of ICMI, to what might be called an experimental approach: the links between mathematics, natural sciences and technology were in the foreground in the early documents of ICMI and also in the papers of its first president, Felix Klein. However, the presence of this perspective in teaching practice is uneven. In this paper, we shall reconstruct first an outline of what happened in three different parts of the world (Europe, USA and Japan) under the direct influence of Klein. Then, we shall report classroom activities realized in the same regions in three different research centres: the Laboratory of Mathematical Machines at the University of Modena and Reggio Emilia, Italy (http://www.mmlab.unimore.it); the pedagogical space of Kinematical Model for Design Digital Library at Cornell, USA (http://kmoddl.library.cornell.edu/); and the Centre for Research on International Cooperation in Educational Development at Tsukuba University, Japan (http://math-info.criced.tsukuba.ac.jp/). They have maintained the reference to concrete materials (either models or instruments), with original interpretations that take advantage of the different cultural conditions. Although in all cases the reference to history is deep and systematic, the synergy with mathematical modelling and with information and communication technologies has been exploited, not to substitute but to complement the advantages of the direct manipulations. 相似文献