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991.
Takahiro Gunji Hiroshi Okonogi Tomomi Sakan Norihiro Takamura Koji Arimitsu Yoshimoto Abe 《应用有机金属化学》2003,17(8):580-588
Polyvinylpolysilsesquioxane (PVPS) organic–inorganic hybrid gel films comprising polyethylene and siloxane backbone linkages were prepared through two routes: trimethoxy(vinyl)silane (VTS) was first subjected to radical polymerization of the vinyl groups, followed by acid‐catalyzed hydrolytic polycondensation of the trimethoxysilyl groups (route A) to afford PVPS; in the second route PVPS was prepared in reverse order (route B). PVPS gel films were transparent and homogeneous. We find that the mechanical and heat‐resisting properties correlate both to the degree of polymerization and the degree of cross‐linking. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
992.
Tran Thi Ngoc Lan Rokuro Nishimura Yoshio Tsujino Kiyoshi Imamura Munehiro Warashina Nguyen Thai Hoang Yasuaki Maeda 《Analytical sciences》2004,20(1):213-217
A passive sampling method was applied to measure the concentrations of air pollutants, such as sulfur dioxide, nitrogen oxides, ammonia, hydrogen chloride, and nitric, formic and acetic acids, in the ambient air at four test sites in the southern region of Vietnam. The monthly averages and the average concentrations of air pollutants during the period from July 2001 to September 2002 are reported here. The concentrations of air pollutants varied widely, depending on the test sites and the sampling periods. The average concentrations of sulfur dioxide in the air during the period from July 2001 to September 2002 at the four test sites were 3.3-16.9 ppb, and those of nitrogen dioxide were 5.4-12.8 ppb. The concentrations of nitrogen monoxide and hydrogen chloride were very low at all of the test sites. The observed concentrations of all of the above-mentioned pollutants were lower than those of the Vietnamese standards of air pollutants. 相似文献
993.
A weighted graph is one in which every edge e is assigned a nonnegative number, called the weight of e. The sum of the weights of the edges incident with a vertex υ is called the weighted degree of υ. The weight of a cycle is defined as the sum of the weights of its edges. In this paper, we prove that: (1) if G is a 2‐connected weighted graph such that the minimum weighted degree of G is at least d, then for every given vertices x and y, either G contains a cycle of weight at least 2d passing through both of x and y or every heaviest cycle in G is a hamiltonian cycle, and (2) if G is a 2‐connected weighted graph such that the weighted degree sum of every pair of nonadjacent vertices is at least s, then for every vertex y, G contains either a cycle of weight at least s passing through y or a hamiltonian cycle. AMS classification: 05C45 05C38 05C35. © 2005 Wiley Periodicals, Inc. J Graph Theory 相似文献
994.
995.
We propose a technique for chromatic dispersion monitoring based on optical time domain level monitoring.Experimental and simulation results show that the technique is effective for the monitoring of dispersion in 42.7-Gbps CS-RZ signals for dynamic dispersion compensation. 相似文献
996.
997.
Ken Kashima Hiroshi Sato Kiyoshi Musha Ken-Ichiro Kanno Tamotsu Takahashi 《Analytical sciences》2007,23(10):1249-1251
Measurements of time of flight (TOF) mobility of organic semiconductors become difficult when the mobility values are high, since the electronic signals overlap with the noise of the short part in drift time. Such noise of the short part in the drift time in the TOF method for measurements of carrier mobility was reduced by three methods: (1) longer distance (3.5 m) between sample and the N(2) laser, (2) optical connection (photo coupler) between the N(2) laser and the pulse generator, and (3) using a digital filter to remove characteristic pulses caused by N(2) laser. Each method showed significant reduction of the noise. When all three methods were applied, 94% of the noise was reduced. The measurement of TOF mobility was demonstrated with TPD (N,N'-diphenyl-N,N'-di(meta-tolyl)benzidine) film. Electronic signals in TOF measurements were clearly observed and the TOF mobility was determined to be 9.0 x 10(-4) cm(2)/V s. 相似文献
998.
Inorganic-organic intercalation compounds comprised of montmorillonite (MMT) and aniline salts with different counter anions were prepared by a mechanochemical processing. The intercalation process and the formed structure of intercalation compounds were investigated via X-ray diffraction analysis. The amounts of intercalated species were very likely dependent on the types of counter anions and increased with decreasing the size of counter anions during the mechanochemical processing. Very interestingly, much larger interlayer expansions of 1.51 nm was observed for aniline hydrofluoride AnF- and aniline hydrochloride AnCl-MMT systems in higher intercalates loading levels, suggesting that neutral guest molecules also introduce within the interlayer regions together with anilinium cations by van der Waals interactions. Judging from the larger interlayer expansions and the size of guest molecules, intercalated species are expected to prefer a tri-molecular layer arrangement with their aromatic rings perpendicular to the silicate sheets. In contrast, for aniline hydrobromide AnBr-MMT, the interlayer expansion was ca. 0.52 nm, which reveals that only anilinium cations are introduced by ion exchange and they probably adopt a vertical orientation in the interlayers. It is inferred that aniline hydroiodide AnI-MMT compounds have a heterogeneous structure containing both anilinium and sodium cations in the interlayers. Different intercalation behaviors during the mechanochemical processing strongly suggest the smaller the size of counter anions, the more guest molecules can be intercalated into the confined clay interlayers in highly ordered arrangements. 相似文献
999.
A sensitive liquid chromatograph/tandem mass spectrometric technique (LC/MS/MS) was applied to determine aliphatic and aromatic carbonyl compounds in ambient air. Traces of the carbonyl compounds were sampled by passing through a Sep-Pak DNPH-silica cartridge. Their derivatives were thus eluted with acetonitrile, separated by reversed-phase liquid chromatography and determined by quadrupole tandem mass spectrometry in an atmospheric pressure chemical ionization (APCI) mode with multiple reaction monitoring (MRM). The detection limits (DL) of the carbonyl compounds were 0.8 - 15 ng/m3. A number of the carbonyl compounds were detected at n.d.- 14 microg/m3 levels. The precursor ion scanning analysis was applied to identify the unknown compounds. 相似文献
1000.
Kiyoshi Yoshimoto 《Discrete Mathematics》2007,307(22):2808-2819
In this paper, we prove that if a claw-free graph G with minimum degree δ?4 has no maximal clique of two vertices, then G has a 2-factor with at most (|G|-1)/4 components. This upper bound is best possible. Additionally, we give a family of claw-free graphs with minimum degree δ?4 in which every 2-factor contains more than n/δ components. 相似文献