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101.
H. Takeuchi Y. Yamamoto Y. Kamo T. Oku M. Nakayama 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,52(3):311-314
We have investigated electric field strengths in the AlxGa1-xN layer, FAlGaN's, of AlxGa1-xN/GaN heterostructures with and without a GaN cap layer using photoreflectance (PR) spectroscopy. Franz-Keldysh oscillations
(FKOs) from the AlxGa1-xN layer are clearly observed in the PR spectra. It is found from analysis of the FKOs that stacking of the cap layer causes
a remarkable enhancement of FAlGaN. This fact demonstrates that the FKO profile is a non-destructive probe for a change of built-in electric field strength
induced by a cap layer. Numerical calculations of FAlGaN based on a Schr?dinger-Poisson equation clarify that the magnitude of the enhancement of FAlGaN is dominated by the cap-layer thickness. 相似文献
102.
Possibility of hydrogen gas storage in carbon (C) and boron nitride (BN) clusters was investigated by molecular orbital calculations. Chemisorption calculation was carried out for C60, B24N24 and B36N36 with changing position of hydrogen atom to compare the bonding energy at carbon, nitrogen and boron, tetragonal and hexagonal rings. Chemisorption calculation of hydrogen for BN clusters showed that hydrogen bondings with nitrogen atoms and tetragonal rings were the most stable. Stability of H2 molecules inside BN and C clusters was also investigated by molecular orbital calculations. C and BN clusters showed possibility of hydrogen storage of 6.5 and 4.9 wt%, respectively. 相似文献
103.
Bunichiro Yamada Fuminori Oku Takahiro Harada 《Journal of polymer science. Part A, Polymer chemistry》2003,41(5):645-654
The addition of propagating radicals of methyl acrylate (MA) and styrene (St) to CH2?C(CO2CH3)CH2? and CH2?C(C6H5)CH2? ω‐end groups of poly(methyl methacrylate) (PMMA) and polystyrene (PSt) was investigated. The end groups were as reactive as MA and St toward the poly(methyl acrylate) (PMA) and PSt radicals, respectively. The adduct radical derived from the two types of PMMA end groups and PMA radicals underwent β fragmentation exclusively to yield PMMA radicals and end groups bound to PMA chains. The addition of PSt radicals to PMMA with CH2?C(CO2Me)CH2? end groups resulted in adduct radicals that underwent β fragmentation and addition to St or coupling with PSt radicals. Adduct radicals formed by the addition of PMA radicals to both types of end groups of PSt exclusively formed C? C bond by coupling with PMA radicals to form branched structures or by addition to MA monomer to give a copolymer. The fate of the adduct radicals was highly dependent on the type of polymer chain and the substituent bound to the end group. Steric congestion of the adduct radical arising from the α‐methyl group of the PMMA chain was considered to be crucial for fragmentation to expel the PMMA radical. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 645–654, 2003 相似文献
104.
Covalently linked dimers of Ru(bpy)3 2+ (3 and 4) connected by two or three carbon atoms were synthesized as models for Ru(bpy)3 2+-containing vinyl polymer (1). The luminescence properties of 3 and 4 were compared with those of its component monomer, 4,4′-dimethyl-2,2′-bipyridine-bis(2,2′-bipyridine)ruthenium(II) complex (2). In excited 3 and 4, intramolecular interaction leading to enhanced quenching was not observed. Electron-transfer quenching of the excited dimer with methylviologen (MV2+) and the zwitterionic viologen, 1,1′-bis(3-sulfopropyl)4,4′-bipyridinium (SPV), was studied and compared with that of 1 and 2. The low quenching efficiency in 1, 3, and 4 systems can be ascribed to the steric hindrance of unexcited ruthenium complex. Energy migration between ruthenium complexes in the excited 1, 3, and 4 can be ruled out from the kinetic evidence. 相似文献
105.
Takumi Kataishi Kotaro Kato Yoshiaki Makihara Yuichi Kitashima Sigeru Ohara Fumiaki Anzai Seiich Inokuma Hiroyuki Oku Masa‐aki Ubukata Yutaka Takahashi Taichi Nakano 《应用有机金属化学》2008,22(12):665-670
A combination catalyst of Pd(dba)2‐PPh3‐CuI‐LiCl or Pd(dba)2‐P(2‐furyl)3‐CuI‐LiCl effectively catalyzed the cross‐coupling of (Z)‐germyl(stannyl)ethenes with aryl halides, providing novel triethyl(2,2‐diarylethenyl)germanes in good to high yields. The reaction proceeds with retention of configuration. Cross‐coupling results in the formation of phenylene or phenyleneethynylene derivatives with terminal stereochemically defined vinylgermane unit(s). Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
106.
107.
Takeo Oku Ryosuke Motoyoshi Kazuya Fujimoto Tsuyoshi Akiyama Balachandran Jeyadevan John Cuya 《Journal of Physics and Chemistry of Solids》2011,72(11):1206-1211
Copper oxide (CuOx) thin films were produced by spin-coating and electrodeposition methods, and their microstructures and photovoltaic properties were investigated. Thin film solar cells based on the Cu2O/C60 and CuO/C60 heterojunction or bulk heterojunction structures were fabricated on F-doped or In-doped SnO2, which showed photovoltaic activity under air mass 1.5 simulated sunlight conditions. Microstructures of the CuOx thin films were examined by X-ray diffraction and transmission electron microscopy, which indicated the presence of Cu2O and CuO nanoparticles. The energy levels of the present solar cells were also discussed. 相似文献
108.
Takanori Hirano Takeo Oku Masayuki Kawaguchi Katsuaki Suganuma 《Molecular Crystals and Liquid Crystals》2013,570(1):787-792
Abstract Boron nitride nanocapsules with gold, iron oxide and germanium nanoparticles were produced. High-resolution electron microscopy and electron energy-loss spectroscopy showed the gold, iron oxide and germanium nanoparticles were encapsulated in the boron nitide sheets. Weak peaks of photoluminescence spectrum were observed from the nanocapsules with germanium nanoparticles. The present work indicates that the boron nitide nanocapsules with conducting, magnetic and semiconductor nanoparticles can be produced by are melting method, and models for the formation mechanism and nano-structures of the boron nitide nanocapsule were proposed. 相似文献
109.
Kikuchi K Ioka A Oku T Tanaka Y Saihara Y Ogumi Z 《Journal of colloid and interface science》2009,329(2):306-309
Water electrolysis is well known to produce solutions supersaturated with oxygen. The oxygen in electrolyzed solutions was analyzed with a dissolved oxygen meter and the Winkler method of chemical analysis. The concentration of oxygen measured with the dissolved oxygen meter agreed with that obtained using the Winkler method. However, measurements using a 10-fold dilution method showed a larger concentration of dissolved oxygen compared to the above methods. We developed a modified Winkler method to measure total oxygen concentration more accurately, which agreed with the results obtained from the 10-fold dilution experiment. The difference in measurements is due to the existence of oxygen nanobubbles, as confirmed by the observation of dynamic light scattering using a laser. Further analysis of the oxygen nanobubbles demonstrated that the stability of the nanobubbles was sufficient for chemical reaction and solvation to bulk solution. 相似文献
110.
Kenji Kikuchi Mayuka Kitawaki Atsushi Suzuki Takeo Oku 《Journal of colloid and interface science》2009,338(2):480-485
By controlling both the kind of ion and the ionic strength of electrolytes in an emulsion polymerization system of vinyl pivalate containing about 1% sodium lauryl sulfate as a surfactant, nanoparticles of polyvinylpivalate having a diameter of about 25 nm were successfully prepared. The use of high concentrations of lithium chloride and lithium sulfate (1.0 mol L−1) prevented the nanoparticles from aggregating and produced nanoparticles sizes of 25–50 nm. Ammonium acetate and sodium acetate, on the other hand, accelerated the aggregate of the nanoparticles. These phenomena were examined in detail and found to be similar to the Hofmeister phenomena and the combination rule proposed by Craig et al. 相似文献