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61.
Tadahiro Kiguchi Hiroyuki Aota Akira Matsumoto 《Journal of polymer science. Part A, Polymer chemistry》2003,41(4):606-615
At the start of our research program concerned with the elucidation of the crosslinking polymerization mechanism leading to interpenetrating polymer network (IPN) formation, in which IPNs consist of both polymethacrylates and polyurethane (PU) networks, this article deals with the polyaddition crosslinking reaction leading to PU network formation. Therefore, 2‐methacryloyloxyethyl isocyanate (MOI) was radically copolymerized with methyl methacrylate (MMA) in the presence of CBr4 as a chain‐transfer agent. The resulting poly(MMA‐co‐MOI)s, having pendant isocyanate (NCO) groups as novel multifunctional polyisocyanates, were used for polyaddition crosslinking reactions with ethylene glycol as a typical diol. The second‐order rate constants depended on both the functionality of poly(MMA‐co‐MOI) and the NCO group concentration. The actual gel points were compared with the theoretical ones calculated according to Macosko's equation; the deviation of the actual gel point from the theoretical value became more remarkable for a greater functionality of poly(MMA‐co‐MOI) and at a lower NCO group concentration or at a lower poly(MMA‐co‐MOI) concentration. These are discussed mechanistically, with consideration given to the significance of intramolecular cyclization and intramolecular crosslinking reactions leading to the shrinkage of the molecular size of the prepolymer, along with the data of the intrinsic viscosities of resulting prepolymers and the swelling ratios of resulting gels. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 606–615, 2003 相似文献
62.
63.
Koike T Yokota S Fujiwara H Sugimoto T Noguchi S de Caro D Valade L 《Inorganic chemistry》2008,47(16):7074-7076
Electrochemical oxidation of a bent donor molecule, ethylenedioxytetrathiafulvalenoquinone-1,3-dithiolmethide ( 2), in chlorobenzene (PhCl)/ethanol containing NBu 4FeCl 4 as a supporting electrolyte is performed using an undoped silicon wafer electrode. Black crystals of 2 6.Fe 2OCl 6.2PhCl are obtained that have a different molecular formula from that of 2 2.FeCl 4 crystals obtained previously using a platinum rod electrode. The new crystal has a structure composed of alternately stacked layers of 2 molecules and Fe 2OCl 6 (2-) ions, whose Fe-O-Fe bond is completely linear and for which the geometry around the Fe atom is almost tetrahedral. The electrical resistivity decreases with temperature until ca. 200 K, but below this temperature, it gently increases. The magnetic susceptibility (chi p) observed can be described by the sum of chi p obeying a Curie-Weiss law for the impurity spins and of chi p obeying a dimer model with a spin-exchange integral ( J approximately -180 K) in each Fe 2OCl 6 (2-) ion, which is also weakly coupled to neighboring Fe 2OCl 6 (2-) ions through an additional exchange interaction. 相似文献
64.
The color of an object appears to be different for elderly and young persons. This is because human visual features vary with on age. In general, the spectral transmittance of the crystalline lens of an elderly person is lower than that of a young person. The low spectral transmittance decreases the brightness of the visual field. This phenomenon affects the color appearance of an image in human visual perception. In this paper, a lightness transform method is proposed to improve the color appearance of images for elderly persons. In the proposed method, colors that are difficult for an elderly person to see are transformed into colors that are easy to see by adding lightness contrast. The performance of the proposed method is confirmed in experiments using digital images. 相似文献
65.
A novel flavanonol (1), three new isoflavones (2-4) and a new flavan-3-ol (5) were isolated along with ten other known flavonoids (6-15) from the methanolic extract of propolis collected from Chitwan, Nepal. Their structures were determined on the basis of spectral analysis. 相似文献
66.
67.
Fujita Y Ohshima N Hasegawa A Schweizer F Takeda T Kiuchi F Hada N 《Molecules (Basel, Switzerland)》2011,16(1):637-651
The novel glycosphingolipid, β-D-GalNAcp(1-->4)[α-D-Fucp(1-->3)]-β-D-GlcNAcp(1-->)Cer (A), isolated from the marine sponge Aplysinella rhax has a unique structure, with D-fucose and N-acetyl-D-galactosamine moieties attached to a reducing-end N-acetyl-D-glucosamine through an α1-->3 and β1-->4 linkage, respectively. We synthesized glycolipid 1 and some non-natural di- and trisaccharide analogues 2-6 containing a D-fucose residue. Among these compounds, the natural type showed the most potent nitric oxide (NO) production inhibitory activity against LPS-induced J774.1 cells. Our results indicate that both the presence of a D-Fucα1-3GlcNAc-linkage and the ceramide aglycon portion are crucial for optimal NO inhibition. 相似文献
68.
Nagatani N Yamanaka K Ushijima H Koketsu R Sasaki T Ikuta K Saito M Miyahara T Tamiya E 《The Analyst》2012,137(15):3422-3426
Influenza virus RNA was amplified by a continuous-flow polydimethylsiloxane microfluidic RT-PCR chip within 15-20 min. The amplified influenza virus RNA was observed with the naked eye, as the red color at the test line, using a lateral flow immunoassay within 1 min. 相似文献
69.
Degeneracy of the eigenvalues of the Pauli–Fierz Hamiltonian with spin 1/2 is proven by the Kramers degeneracy theorem. The
Pauli–Fierz Hamiltonian at fixed total momentum is also investigated.
相似文献
70.
The color appearance of a food image is very important for making it look delicious. Many food images acquired in low illumination environments do not give delicious impressions because of the deterioration of their color appearance. We propose an image enhancement method to improve the color appearance of a food image acquired in a low illumination environment. In the proposed method, the lightness of each pixel is first enhanced within a color gamut on an equal hue plane in the CIELAB color space. The boundary of the color gamut is given by a lookup table calculated in advance. Then, when the hue of the pixel is attributed to foods, the chroma is enhanced within the color gamut. In this case, we consider Helmholtz–Kohlrausch (H-K) effect, which indicates the relation of the hue, chroma, and lightness in human visual perception. According to H-K effect, the perceived lightness increases as the chroma is enhanced. Therefore, the perceived lightness is preserved after the chroma enhancement, so that the food image is not too enhanced. To verify the effectiveness of the proposed method, experiments are conducted using several food images. 相似文献