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排序方式: 共有127条查询结果,搜索用时 31 毫秒
71.
K.-I. Akabori K. Tanaka A. Takahara T. Kajiyama T. Nagamura 《The European physical journal. Special topics》2007,141(1):173-180
Mechanical relaxation behavior in ultrathin polystyrene
(PS) films supported on silicon oxide (SiOx) and gold (Au) substrates
has been studied by dynamic viscoelastic measurement. Based on the method,
effects of free surface and substrate interface on the segmental dynamics
were discussed. In the case of thin PS films with a thickness of
approximately 200 nm, αa-relaxation process corresponding to
the segmental motion did not show any deviation from the bulk behavior. In
contrast, for the films thinner than about 50 nm, the relaxation time
distribution for the αa-process became broader, probably due to
a mobility gradient in the surface and interfacial regions. When we
sandwiched an ultrathin PS film between SiOx layers, another relaxation
process, in addition to the original αa-process, appeared at a
higher temperature side that we assigned to the interfacial αa-relaxation
process. However, this was never seen for an ultrathin PS
film between Au layers, implying that restriction from the substrate
interface might be weak in this case. 相似文献
72.
T. Yamaguchi K. Yoshida P. Smirnov T. Takamuku S. Kittaka S. Takahara Y. Kuroda M.-C. Bellissent-Funel 《The European physical journal. Special topics》2007,141(1):19-27
The microscopic structure and dynamic properties of water,
methanol, and acetonitrile confined in mesoporous MCM-41 materials
have been investigated under monolayer and capillary-condensation
conditions as a function of pore size and temperature by in situ
FTIR and X-ray diffraction and quasi-elastic neutron scattering
techniques. Both interfacial and confinement effects on the
structure and dynamics of the liquids in hydrophilic pores are
discussed at the molecular level. 相似文献
73.
Otsuka H Aotani K Higaki Y Takahara A 《Journal of the American Chemical Society》2003,125(14):4064-4065
A novel polymer hybridization method, "polymer scrambling", was developed on the basis of the macromolecular radical crossover reaction between the main chains of dynamic covalent polymers. The macromolecular crossover reaction was successfully monitored by GPC and NMR measurements. The present methodology is innovative for the preparation of novel polymer hybrid materials at the nanometer scale. 相似文献
74.
Amamoto Y Higaki Y Matsuda Y Otsuka H Takahara A 《Journal of the American Chemical Society》2007,129(43):13298-13304
Programmed thermodynamic formation of star-like nanogels from designed diblock copolymers with thermally exchangeable dynamic covalent bonds in their side chains and structure analysis of the nanogels were performed. Linear diblock copolymers that consist of poly(methyl methacrylate) block and random copolymer block of methyl methacrylate (MMA) and methacrylic esters with alkoxyamine moiety were prepared by atom transfer radical polymerization (ATRP). By heating the diblock copolymers in anisole, a cross-linking reaction occurred as a result of the radical crossover reaction of alkoxyamine moieties to afford star-like nanogels. Kinetic studies have revealed that the cross-linking behavior reaches equilibrium at a given reaction time, with characteristic reaction behaviors for thermodynamic reactions being observed. The equilibrium structures of the star-like nanogels were controlled by the initial concentrations of diblock copolymers as well as their compositions and molecular weights. Furthermore, by heating the star-like nanogels with excess alkoxyamine, linear polymers were successfully regenerated. The molecular weights and sizes of the nanogels were evaluated by gel permeation chromatography-multiangle laser light scattering (GPC-MALLS) and small-angle X-ray scattering (SAXS) measurements, respectively, and the morphologies of the nanogels were directly observed by scanning force microscopy (SFM). 相似文献
75.
Park S Lee Y Kim B Lee J Jeong Y Noh J Takahara A Sohn D 《Chemical communications (Cambridge, England)》2007,(28):2917-2919
Surface modified imogolite fiber, hydrated aluminium silicate that has the shape of a rigid hollow cylinder, was aligned with consistent nano spacing and was visualized by scanning tunneling microscopy. 相似文献
76.
Ju MJ Yang DH Takahara N Hayashi K Toko K Lee SW Kunitake T 《Chemical communications (Cambridge, England)》2007,(25):2630-2632
Highly sensitive and selective detection of 2,4-DNT, a representative explosive, was achieved by the synergic effect of molecular imprinting and host (cyclodextrin)-guest interaction in ultrathin layers of TiO(2) and SiO(2) gel; the detection limit using cSPI measurements reached nM concentration. 相似文献
77.
78.
Takanori Takahashi Kazuhiro Ikegaya Hirohmi Watanabe Nobukazu Miyagawa Shigeru Takahara Tsuguo Yamaoka 《先进技术聚合物》2000,11(6):307-315
A novel water‐dispersible reactive microgel, which had a diameter of 40–90 nm, was synthesized for photopolymer materials. The microgels have segments with substituted ammonium groups, to provide water solubility, in their polymer networked structure. It has unsaturated groups connected to the quaternary nitrogens by ionic bonding (I‐type microgel). The I‐type microgel was compared with one that has methacryloyl groups connected with the quaternary nitrogens of the microgel by covalent bonding (C‐type microgel). The I‐type microgels were able to separately control the modified amount of quaternary nitrogen and methacryloyl group. In the presence of 2,4‐diethylthioxantone as a photoinitiator and pentaerthritol triacrylate as a crosslinker, the photopolymer containing the C‐type or I‐type microgels had sensitivity high enough for practical use. Not only the amount of the methacryloyl group of the microgel but the amount of the quaternary nitrogen affected the sensitivity and the rate of polymerization of the water‐dispersible photopolymer containing the I‐type microgels. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
79.
Poly(p-hydroxystyrene)s (PHSs) partially protected by tetrahydropyranyl (THP), PPT-x, containing 2,2′-bis(4-(2-(vinyloxy)ethoxy)phenyl)propane as a crosslinking agent were used as three-component photopolymers in combination with diphenyliodonium 9,10-dimethoxyanthracene-2-sulfonate (DIAS) as a photoacid generator. The PPT-x with a higher THP-protecting ratio was deprotected at higher temperatures than the PPT-x with a lower THP-protecting ratio. The conversions of vinyl ether compound in the photopolymer films were not related to the THP-protecting ratios in PPT-x and increased with increasing baking time. Under different THP-protecting ratios and prebaking temperatures, the PPT-x showed varying lithographic behavior between a positive-working mode and a negative-working mode. These three-component photopolymer solutions of PPT-x have good preservation stability. © 1998 John Wiley & Sons, Ltd. 相似文献
80.
The copolymers containing a carboxyl group were used as the two-component photopolymers in combination with dimethyl 4-(o-nitrophenyl)-2,6-dimethyl-1,4-dihydro-3,5-pyridinedicarboxylate (NMHP) as a photobase generator. Under irradiation by 365 nm light, NMHP is converted to dimethyl 4-(o-nitrosophenyl)-2,6-dimethyl-3,5-pyridinedicarboxylate (NMP). NMP acts as a base catalyst for the thermal decarboxylation of a carboxyl group in the polymer. The decarboxylation in the polymer provides a negative-working photoresist under the additional flood-exposure of 365 nm light before development. This process is called the photoassisted contrast (PAC) process. NMHP acts as a dissolution inhibitor for the aqueous base development of the polymers containing a carboxyl group but NMP promotes the dissolution of the polymers. This change in the solubility inhibition of NMHP offers a positive-working photoresist without the process of post-exposure baking (PEB) and the PAC process. Therefore, NMP, the photoproduct of NMHP, produces dual-tone-mode photoresists with the copolymers containing a carboxyl group. © 1998 John Wiley & Sons, Ltd. 相似文献