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41.
Juthathip Fangkangwanwong Mitsuru Akashi Toshiyuki Kida Suwabun Chirachanchai 《Macromolecular rapid communications》2006,27(13):1039-1046
Summary: A chitosan‐hydroxybenzotriazole (HOBt) aqueous solution prepared by simply mixing chitosan and HOBt in water provides an effective system to functionalize chitosan in an aqueous environment. This aqueous solution in combination with water‐soluble carbodiimide (WSC) allows the conjugation of functional groups onto chitosan under mild conditions without requiring any organic solvents or acid and heat. In this contribution, a series of model reactions that use a novel water‐based system of chitosan to functionalize the polymer with boc‐L ‐phenylalanine, poly(ethylene glycol) methyl ether, and dicarboxylated poly(ethylene glycol) is demonstrated.
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43.
Hiroharu Ajiro Daisuke Kamei Mitsuru Akashi 《Journal of polymer science. Part A, Polymer chemistry》2008,46(17):5879-5886
Methacrylic acid (MAA), methyl methacrylate (MMA), methacrylamide, and oligomers of MAA and MMA were selected as a model of active radical species in living template polymerization using stereocomplex formation. The adsorption behaviors of the aforementioned model compounds were examined toward porous isotactic‐(it‐) poly(methyl methacrylate) (PMMA) ultrathin films on a quartz crystal microbalance, which was prepared by the extracting of syndiotactic‐(st‐) poly(methacrylic acid) (PMAA) from it‐PMMA/st‐PMAA stereocomplexes. The apparent predominant adsorption of oligomers to monomers was observed in both PMAA and PMMA oligomers, suggesting that the mechanism of template polymerization follows the pick up mechanism. Although vinyl monomers were not incorporated into the porous it‐PMMA ultrathin film, both PMMA and PMAA oligomers were adsorbed at the initial stages. However, adsorbed amounts were limited to about 5 and 15% at 0.1 mol L?1, respectively, which are much smaller values than corresponding st‐polymers. The results imply that radical coupling reaction is prevented during template polymerization to support the resulting living polymerization. ATR‐IR spectral patterns of oligomer complexes and it‐PMMA slightly changed in both cases, suggesting complex formation. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5879–5886, 2008 相似文献
44.
Specific thermosensitive volume change of biopolymer gels derived from propylated poly(γ-glutamate)s
Taiki Shimokuri Tatsuo Kaneko Mitsuru Akashi 《Journal of polymer science. Part A, Polymer chemistry》2004,42(18):4492-4501
Thermosensitive biopolymers with an amphipathic structure were synthesized through the propyl esterification of the carboxyl groups of poly(γ-glutamic acid) (γ-PGA). The clouding temperature on heating was controlled by the addition of different amounts of NaCl and by the degree of esterification. The clearing temperature on cooling was independent of the aqueous milieu, presumably because of the strong multiple hydrogen bonds between the polymer chains formed in the collapsed state. The hydrogel of γ-PGA propylate crosslinked by a chemical reaction with hexamethylene diisocyanate also showed pH-responsive and thermoresponsive shrinking, but the volume recovery was incomplete during the cooling process. A Fourier transform infrared/attenuated total reflection study showed that the incomplete volume recovery might be associated with the amide hydrogen bonding being strengthened by the chemical crosslinkage. The addition of urea made the volume change complete. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4492–4501, 2004 相似文献
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Diamond powders with silicon additives were shock compressed by using a flyer impact technique. Pressure and temperature histories in the powder mixtures were numerically simulated in order to determine the optimum experimental condition which resulted in the highest Vicker's hardness. This was found to be: an initial diamond particle size of 2–4m at 7.2 % silicon by volume. The results of the simulations were consistent with the distribution of the microstructure and the microhardness in the compact.This article was processed using Springer-Verlag TEX Shock Waves macro package 1990. 相似文献
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48.
Masaaki Abe Haruo Akashi Kiyoshi Isobe Akihiko Nakanishi Atsushi Yagasaki 《Journal of Cluster Science》1996,7(1):103-107
The methallyl moieties of [{(3-C4H7)2Rh}2(V4O12)]2– couple to yield 2,5-dimethyl-1,5-hexadiene in a selective manner by the action of P(OEt),3, while the reaction of [(
3-C4H7)2 Rh(acac)] with P(OEt)3 produces a mixture of organic compounds. The result shows that the vanadate support has a significant influence on the reactivity of organometallic complexes. 相似文献
49.
YanCAI MingQingCHEN JuanXU PinFangWU AkashiMITSURU XiaoHuaHUAN 《中国化学快报》2004,15(9):1109-1112
Poly (N-vinylacetamide) (PNVA) was synthesized by the free radical polymerization and its samarium (Ⅲ) binary complex was prepared and characterized by means of IR, UV-vis, X-ray photoelectron spectroscopy (XPS) and fluorescence spectra. The fluorescent intensity of samarium (Ⅲ) characteristic emission was increased significantly due to efficient energy transfer from polymeric ligand to Sm (Ⅲ) ion in the complex. 相似文献
50.
Sunatsuki Y Ohta H Kojima M Ikuta Y Goto Y Matsumoto N Iijima S Akashi H Kaizaki S Dahan F Tuchagues JP 《Inorganic chemistry》2004,43(14):4154-4171
The [Fe(II)(H(3)L)](BF(4))(2).3H(2)O (1) complex was synthesized, where H(3)L (tris[[2-[(imidazole-4-yl)methylidene]amino]ethyl]amine) is a tripodal ligand obtained by condensation of tris(2-aminoethyl)amine and 4-formylimidazole (fim) in a 1:3 molar ratio. Starting from 1, a series of complexes, [Fe(II)(H(1.5)L)](BF(4))(0.5) (2) (=[Fe(II)(H(3)L)][Fe(II)(L)]BF(4)), [Fe(H(1.5)L)]BF(4) (3) (=[Fe(II)(H(3)L)][Fe(III)(L)](BF(4))(2)), [Fe(III)(H(3)L)](BF(4))(3).fim.H(2)O (4), and [Fe(III)(L)].2.5H(2)O (5), has been synthesized and characterized. The single-crystal X-ray structure of each complex has been determined. The Fe(II) compound, 2, and a mixed valence Fe(II)-Fe(III) compound, 3, involve formally hemi-deprotonated ligands, H(1.5)L. The structure of 3 consists of a homochiral two-dimensional assembled sheet, arising from the intermolecular hydrogen bonds between [Fe(II)(H(3)L)](2+) and [Fe(III)(L)](0) (3). All but 5 exhibit spin crossover between low-spin (LS) and high-spin (HS) states. This is a rare case where both Fe(II) and Fe(III) complexes containing the same ligand exhibit spin-crossover behavior. Magnetic susceptibility and M?ssbauer studies showed that 3 has three accessible electronic states: LS Fe(II)-LS Fe(III), HS Fe(II)-LS Fe(III), and HS Fe(II)-HS Fe(III). Compounds 1-3 show the light-induced excited spin-state trapping effect at the Fe(II) sites upon irradiation with green light. The solution magnetic properties, electronic spectra, and electrochemical properties of 1, 4, and 5 were also studied. 相似文献