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71.
Hitoshi Tanaka Hirofumi Kawai Tsuneyuki Sato Tadatoshi Ota 《Journal of polymer science. Part A, Polymer chemistry》1989,27(5):1741-1748
Polymerizations of some vinyl monomers were carried out with 2,2′-azobisisobutyronitrile at 60°C in the presence of a methyl methacrylate (MMA) dimer ( I ) or a MMA polymer ( II ) with a double bond at their ends to confirm the polymerization reactivity of unsaturated end group generated during the disproportionation in termination reaction of MMA polymerization. It was found that the polymerizations of α-monosubstituted monomers have been much retarded than those of α,α-disubstituted monomers by the addition of I . Kinetic study on MMA and methyl acrylate polymerizations showed that the rate constant for the reaction of a propagating radical with I was 5.4 and 29.2 L/mol s in their polymerizations, respectively. ESR study using I and II suggested that an addition reaction was a predominant mechanism for the reaction of an unsaturated end group with a radical rather than a hydrogen abstraction. 相似文献
72.
Tsuneyuki Sato Hidekazu Mukuno Hirotaka Ishida Makiko Seno Tomohiro Hirano 《Journal of polymer science. Part A, Polymer chemistry》2002,40(4):573-582
Vinyl thiocyanatoacetate (VTCA) was synthesized, and its radical polymerization behavior was studied in acetone with dimethyl 2,2′‐azobisisobutyrate (MAIB) as an initiator. The initial polymerization rate (Rp) at 60 °C was expressed by Rp = k[MAIB]0.6±0.1 [VTCA]1.0±0.1 where k is a rate constant. The overall activation energy of the polymerization was 112 kJ/mol. The number‐average molecular weights of the resulting poly (VTCA)s (1.4–1.6 × 104) were almost independent of the concentrations of the initiator and monomer, indicating chain transfer to the monomer. The chain‐transfer constant to the monomer was estimated to be 9.6 × 10?3 at 60 °C. According to the 1H and 13C NMR spectra of poly (VTCA), the radical polymerization of VTCA proceeded through normal vinyl addition and intramolecular transfer of the cyano group. The cyano group transfer became progressively more important with decreasing monomer concentration. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 573–582, 2002; DOI 10.1002/pola.10137 相似文献
73.
Takayuki Otsu Tsuneyuki Sato Munan Ko 《Journal of polymer science. Part A, Polymer chemistry》1969,7(12):3329-3336
In order to clarify the mechanism of initiation by dimethylbenzylanilinium chloride (DMBAC), the polymerization of methyl methacrylate with DMBAC has been investigated at 60–80°C. From the results of kinetic and tracer studies, it was found that this polymerization proceeded via a radical mechanism and benzyl radical was not an initiating species. However, it was also noted that DMBAC easily dissociated into dimethylaniline and benzyl chloride under the present conditions, and the overall activation energy for the methyl methacrylate polymerization was 14.6 kcal/mole. These observations indicate that initiating radicals other than benzyl radical, i.e., phenyl or methyl radicals, may be produced through a redox interaction between DMBAC and dimethylaniline dissociated from DMBAC. 相似文献
74.
Kobayashi T Ohmiya H Yorimitsu H Oshima K 《Journal of the American Chemical Society》2008,130(34):11276-11277
Cobalt-catalyzed reactions of haloalkanes with dimethylphenylsilylmethylmagnesium chloride result in highly regioselective dehydrohalogenation. The reaction does not follow the conventional E2 elimination mechanism but includes beta-hydride elimination from the corresponding alkylcobalt intermediate. The interesting reaction mechanism of the cobalt-catalyzed dehydrohalogenation offered unique transformations that are otherwise difficult to attain. 相似文献
75.
Makiko Seno Toshiya Ikezumi Takafumi Sumie Yasuhito Masuda Tsuneyuki Sato 《Journal of polymer science. Part A, Polymer chemistry》2000,38(11):2098-2105
The radical polymerization of N‐tert‐butyl‐N‐allylacrylamide (t‐BAA) was carried out in a dimethyl sulfoxide/H2O mixture in the presence of β‐cyclodextrin (β‐CD). The polymerization proceeded with the complete cyclization of the t‐BAA unit and yielded optically active poly(t‐BAA). The IR spectrum of the obtained polymer showed that the cyclic structure in the polymer was a five‐membered ring. The optical activity of poly(t‐BAA) increased with an increasing molar ratio of β‐CD to the t‐BAA monomer. The interaction of β‐CD with t‐BAA was confirmed by 1H NMR and 13C NMR analyses of the polymerization system. It is suggested that interaction of the t‐BAA monomer with the hydrophobic cavity of β‐CD plays an important role in the asymmetric cyclopolymerization of t‐BAA. The radical copolymerization of t‐BAA with styrene (St), methyl methacrylate, ethyl methacrylate, or benzyl methacrylate (BMA) also produced optically active copolymers with a cyclic structure from the t‐BAA unit. St and BMA carrying a phenyl group were predicted to compete with t‐BAA for interaction with β‐CD in the copolymerization system. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2098–2105, 2000 相似文献
76.
Tsuneyuki Sato Toru Takahashi Makiko Seno Tomohiro Hirano 《Journal of polymer science. Part A, Polymer chemistry》2001,39(24):4206-4213
A combined system of sodium tetraphenylborate (STPB) and p‐chlorobenzenediazonium tetrafluoroborate (CDF) serves as an effective initiator at low temperatures for acrylate monomers such as methyl methacrylate (MMA), ethyl acrylate, and di‐2‐ethylhexyl itaconate. The polymerization of MMA with the STPB/CDF system has been kinetically investigated in acetone. The polymerization shows a low overall activation energy of 60.3 kJ/mol. The polymerization rate (Rp) at 40 °C is given by Rp = k[STPB/CDF]0.5[MMA]1.6, when the molar ratio of STPB to CDF is kept constant at unity, suggesting that STPB and CDF form a complex with a large stability constant and play an important role in initiation and that MMA participates in the initiation process. From the results of a spin trapping study, p‐chlorophenyl and phenyl radicals are presumed to be generated in the polymerization system. A plausible initiation mechanism is proposed on the basis of kinetic and electron spin resonance results. A large solvent effect on the polymerization can be observed. The largest Rp value in dimethyl sulfoxide is 11 times the smallest value in N,N‐dimethylformamide. The copolymerization of MMA and styrene with the STPB/CDF system gives results somewhat different from those of conventional radical copolymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4206–4213, 2001 相似文献
77.
Makiko Seno Hironori Fukunaga Tsuneyuki Sato 《Journal of polymer science. Part A, Polymer chemistry》1998,36(16):2905-2912
The effect of fullerene (C60) on the radical polymerization of methyl methacrylate (MMA) in benzene was studied kinetically and by means of ESR, where dimethyl 2,2′-azobis(isobutyrate) (MAIB) was used as initiator. The polymerization rate (Rp) and the molecular weight of resulting poly(MMA) decreased with increasing C60 concentration ((0–2.11) × 10−4 mol/L). The molecular weight of polymer tended to increase with time at higher C60 concentrations. Rp at 50°C in the presence of C60 (7.0 × 10−5 mol/L) was expressed by Rp = k[MAIB]0.5[MMA]1.25. The overall activation energy of polymerization at 7.0 × 10−5 mol/L of C60 concentration was calculated to be 23.2 kcal/mol. Persistent fullerene radicals were observed by ESR in the polymerization system. The concentration of fullerene radicals was found to increase linearly with time and then be saturated. The rate of fullerene radical formation increased with MAIB concentration. Thermal polymerization of styrene (St) in the presence of resulting poly(MMA) seemed to yield a starlike copolymer carrying poly(MMA) and poly(St) arms. The results (r1 = 0.53, r2 = 0.56) of copolymerization of MMA and St with MAIB at 60°C in the presence of C60 (7.15 × 10−5 mol/L) were similar to those (r1 = 0.46, r2 = 0.52) in the absence of C60. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2905–2912, 1998 相似文献
78.
Makiko Seno Yoshinori Kawamura Tsuneyuki Sato 《Journal of polymer science. Part A, Polymer chemistry》1996,34(15):3121-3130
The effects of SnCl4 on the radical polymerization of N-allyl-N-phenylmethacrylamide (APM) and N-allyl-N-phenylacrylamide (APA) were investigated. The polymerizations of APM and APA with dimethyl 2,2-azobisisobutyrate (MAIB) were carried out at 50°C in benzene at various concentrations (0-1.0 mol/L) of SnCl4. The polymerization rates showed a maximum on varying the SnCl4 concentration, while the molecular weights of the resulting poly(APM) and poly(APA) were decreased with increasing SnCl4 concentration. In both systems, the degree of cyclization of polymers were decreased with the SnCl4 concentration. From the IR results, the cyclic structure of the resulting poly(APM)s was confirmed to be five-membered, whereas poly(APA)s contained not only five-membered but also six-membered rings. The 1H-NMR examination on the interactions of APM and APA with SnCl4 revealed that these monomers form 1:1 and 2:1 complexes with SnCl4 with fairly large stability constants. Copolymerizations of APM (M1) with methyl methacrylate (MMA) and styrene (St) (M2) were investigated at 60°C in benzene in the absence of SnCl4. APM units were found to be incorporated exclusively as five-membered rings in the resulting copolymer. Monomer reactivity ratios were estimated to be r1 = 0.29, r2 = 4.88 for APM/MMA and r1 = 0.66, r2 = 5.39 for APM/St. The presence of equimolar (to APM) SnCl4 was found to enhance the reactivity of APM toward poly(MMA) radical; r1 = 0.24, r2 = 2.56. © 1996 John Wiley & Sons, Inc. 相似文献
79.
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