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排序方式: 共有119条查询结果,搜索用时 62 毫秒
31.
T. Ohsaka Y. Shibata K. Ishi S. Takahashi M. Ishii Y. Fujiki 《Solid State Communications》1985,55(12):1119-1121
The reflection spectra of the one-dimensional ionic conductors K1.6Al1.6Ti6.4O16 and Rb1.49Al1.65Ti6.35O15.92 have been measured for the polarizations E ∥ c (channel direction) and E 6 c in the frequency region 60–2000 cm-1. The spectra of these two compounds are very similar with their features and have the same number of bands. The vibrational mode frequencies are obtained from a Kramers-Kronig analysis for each polarized reflectivity spectrum. A comparison of the corresponding mode frequencies for both priderites shows that only the lowest frequency mode observed in the E 6 c spectra is strongly associated with the alkali ion, while the others are not. The effect due to the non-stoichiometry is not found in the infrared reflection spectra. 相似文献
32.
Takuya Sato Nobuyuki Hara Nobuo Tajima Atsushi Sudo Michiya Fujiki Yoshitane Imai 《Tetrahedron letters》2018,59(17):1619-1622
Although chiral 1,1′-binaphthalene-2,2′-diyl-O,O-bis(N,N-dimethylthiocarbamate) (1) revealed no circularly polarized luminescence (CPL) signals, Newman–Kwart rearrangement of O-thiocarbamate groups at 1 yielded clear CPL signals from 1,1′-binaphthalene-2,2′-diyl-S,S-bis(N,N-dimethylthiocarbamate) (2), which acts as a CPL-gen molecule. 相似文献
33.
Green tea: Health benefits as cancer preventive for humans 总被引:8,自引:0,他引:8
Fujiki H 《Chemical record (New York, N.Y.)》2005,5(3):119-132
Green tea is an acknowledged cancer preventive in Japan. The aim of this review article is to develop the concept of cancer prevention with green tea beverage for humans, which has largely been our exclusive research territory. This paper briefly reviews several topics, beginning with the introduction of our initial work on penta-O-galloyl-beta-D-glucose and (-)-epigallocatechin gallate (EGCG), the main constituent of green tea extract. The mechanisms of EGCG action, particularly the reduction of TNF-alpha are discussed, and we show how use of 3H-EGCG revealed a wide range of target organs for cancer prevention. The results of an epidemiological study in Saitama Prefecture allowed us to determine the cancer preventive amount of green tea-10 Japanese-size cups per day, about 2.5 g green tea extract-which made it possible for us to introduce the two-stage strategy of cancer prevention with green tea. The first stage is the delay of cancer onset for the general population. The second stage is the prevention of recurrence of cancer for patients following cancer treatment. Combination cancer prevention with green tea and cancer preventive drugs is proving especially beneficial for Japanese, who drink green tea every day. And finally, the stimulating comments of Prof. Jim Watson have encouraged green tea scientists. 相似文献
34.
Cheng-yuan Huang Ning Wang Katsumasa Fujiki Yuji Otsuka Masao Akamatsu Yukari Fujimoto 《Journal of carbohydrate chemistry》2013,32(6):289-298
The N-Troc (2,2,2-trichloroethoxycarbonyl) groups in glucosamine and muramic acid derivatives were removed by treatment with tetrabutylammonium fluoride (TBAF) under mild conditions. The use of Troc protection for the amino group in aminosugars such as glucosamine is increasing the importance for selective and efficient glycosylation, and the cleavage method described here will expand the available opportunities for using the Troc group in the preparation of a variety of glycans. This cleavage is especially advantageous for compounds that are labile or may be decomposed under acidic conditions, strong basic conditions, or reductive conditions. 相似文献
35.
Yoshitaka Miyamoto Michiya Fujiki Kotohiro Nomura 《Journal of polymer science. Part A, Polymer chemistry》2004,42(17):4248-4265
The ring‐opening metathesis polymerization (ROMP) of norbornenes containing acetyl‐protected glucose [2,3,4,6‐tetra‐O‐acetyl‐glucos‐1‐O‐yl 5‐norbornene‐2‐carboxylate ( 1 )] and maltose [2,3,6,2′,3′,4′,6′‐hepta‐O‐acetyl‐maltos‐1‐O‐yl 5‐norbornene‐2‐carboxylate ( 2 )] was explored in the presence of Mo(N‐2,6‐iPr2C6H3)(CHCMe2Ph)(OtBu)2 ( A ), Ru(CHPh)(Cl)2(PCy3)2 ( B ; Cy = cyclohexyl), and Ru(CHPh)(Cl)2(IMesH2)(PCy3) ( C ; IMesH2 = 1,3‐dimesityl‐4,5‐dihydromidazol‐2‐ylidene). The polymerizations promoted by B and A proceeded in a living fashion with exclusive initiation efficiency, and the resultant polymers possessed number‐average molecular weights that were very close to those calculated on the basis of the monomer/initiator molar ratios and narrow molecular weight distributions (weight‐average molecular weight/number‐average molecular weight < 1.18) in all cases. The observed catalytic activity of B was strongly dependent on both the initial monomer concentration and the solvent employed, whereas the polymerization initiated with A was completed efficiently even at low initial monomer concentrations. The polymerization with C also took place efficiently, and even the polymerization with 1000 equiv of 1 was completed within 2 h. First‐order relationships between the propagation rates and the monomer concentrations were observed for all the polymerization runs, and the estimated rate constants at 25 °C increased in the following order: A > C > B . On the basis of these results, we concluded that ROMP with A was more suitable than ROMP with B or C for the efficient and precise preparation of polymers containing carbohydrates. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4248–4265, 2004 相似文献
36.
Kohei Mishima Daiki Kaji Prof. Dr. Michiya Fujiki Prof. Dr. Yoshitane Imai 《Chemphyschem》2021,22(17):1728-1737
Herein, magnetic circularly polarized luminescence (CPL) (MCPL) spectroscopy was conducted to analyze an EuIII(hfa)3 complex with three chiral PIII-ligands. Resultantly, (R)-chirality luminophores with S-up orientation and (S)-chirality luminophores with N-up orientation were observed to possess symmetrical mirror image spectra, i. e., they were enantiomers. Similarly, the (R)-chirality luminophores with N-up orientation and the (S)-chirality luminophores with S-up orientation were also enantiomers. Contrarily, (R)-S-up and (S)-S-up were diastereomers and did not possess a mirror-image relationship. Likewise, (R)-N-up and (S)-N-up were diastereomers. The J-dependency of gMCPL and gCPL datasets suggested that the N-up/S-up external magnetic field, with the aid of chiral PIII-ligands, increased the gMCPL values by two- to sixteen-fold and modulated the gMCPL signs at J=1–4. Additionally, the origins of the nonideal mirror-symmetric CPL and MCPL spectral characteristics of EuIII(hfa)3 with three chiral PIII-ligands were discussed in terms of parity (space-inversion, P)-symmetry, time-reversal (T)-symmetry, and PT-symmetry laws. 相似文献
37.
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39.
Tokunaga N Fujiki Y Shinkai S Sada K 《Chemical communications (Cambridge, England)》2006,(34):3617-3618
Face-selective decoration of a single crystal constructed from 1-pyrenemethylammonium chloride by an anionic porphyrin dye is reported. CLSM observations indicated that the {001} face of the single crystal was selectively coated by the anionic porphyrin (TPPS). This novel achievement could be the first step for preparation of multi-component composite materials mediated by anisotropy of organic single crystals toward photochemical devices. 相似文献
40.
Noda K Ohuchi Y Hashimoto A Fujiki M Itoh S Iwatsuki S Noda T Suzuki T Kashiwabara K Takagi HD 《Inorganic chemistry》2006,45(3):1349-1355
Controlled-potential electrochemical oxidation of cis-[Ru(ROCS2)2(PPh3)2] (R = Et, iPr) yielded corresponding Ru(III) complexes, and the crystal structures of cis-[Ru(ROCS2)2(PPh3)2] and trans-[Ru(ROCS2)2(PPh3)2](PF6) were determined. Both pairs of complexes exhibited almost identical coordination structures. The Ru-P distances in trans-[Ru(III)(ROCS2)2(PPh3)2](PF6) [2.436(3)-2.443(3) A] were significantly longer than those in cis-[Ru(II)(ROCS2)2(PPh3)2] [2.306(1)-2.315(2) A]: the smaller ionic radius of Ru(III) than that of Ru(II) stabilizes the trans conformation for the Ru(III) complex due to the steric requirement of bulky phosphine ligands while mutual trans influence by the phosphine ligands induces significant elongation of the Ru(III)-P bonds. Cyclic voltammograms of the cis-[Ru(ROCS2)2(PPh3)2] and trans-[Ru(ROCS2)2(PPh3)2]+ complexes in dichloromethane solution exhibited typical dual redox signals corresponding to the cis-[Ru(ROCS2)2(PPh3)2](+/0) (ca. +0.15 and +0.10 V vs ferrocenium/ferrocene couple for R = Et and iPr, respectively) and to trans-[Ru(ROCS2)2(PPh3)2](+/0) (-0.05 and -0.15 V vs ferrocenium/ferrocene for R = Et and iPr, respectively) couples. Analyses on the basis of the Nicholson and Shain's method revealed that the thermal disappearance rate of transient trans-[Ru(ROCS2)2(PPh3)2] was dependent on the concentration of PPh3 in the bulk: the rate constant for the intramolecular isomerization reaction of trans-[Ru(iPrOCS2)2(PPh3)2] was determined as 0.338 +/- 0.004 s(-1) at 298.3 K (deltaH* = 41.8 +/- 1.5 kJ mol(-1) and deltaS* = -114 +/- 7 J mol(-1) K(-1)), while the dissociation rate constant of coordinated PPh3 from the trans-[Ru(iPrOCS2)2(PPh3)2] species was estimated as 0.113 +/- 0.008 s(-1) at 298.3 K (deltaH* = 97.6 +/- 0.8 kJ mol(-1) and deltaS* = 64 +/- 3 J mol(-1) K(-1)), by monitoring the EC reaction (electrode reaction followed by chemical processes) at different concentrations of PPh3 in the bulk. It was found that the trans to cis isomerization reaction takes place via the partial dissociation of iPrOCS2(-) from Ru(II), contrary to the previous claim that it takes place by the twist mechanism. 相似文献