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71.
Atsushi Suenaga Dr. Tetsu Narumi Dr. Noriyuki Futatsugi Dr. Ryoko Yanai Yousuke Ohno Dr. Noriaki Okimoto Dr. Makoto Taiji Dr. 《化学:亚洲杂志》2007,2(5):591-598
Short peptides that fold into β‐hairpins are ideal model systems for investigating the mechanism of protein folding because their folding process shows dynamics typical of proteins. We performed folding, unfolding, and refolding molecular dynamics simulations (total of 2.7 μs) of the 10‐residue β‐hairpin peptide chignolin, which is the smallest β‐hairpin structure known to be stable in solution. Our results revealed the folding mechanism of chignolin, which comprises three steps. First, the folding begins with hydrophobic assembly. It brings the main chain together; subsequently, a nascent turn structure is formed. The second step is the conversion of the nascent turn into a tight turn structure along with interconversion of the hydrophobic packing and interstrand hydrogen bonds. Finally, the formation of the hydrogen‐bond network and the complete hydrophobic core as well as the arrangement of side‐chain–side‐chain interactions occur at approximately the same time. This three‐step mechanism appropriately interprets the folding process as involving a combination of previous inconsistent explanations of the folding mechanism of the β‐hairpin, that the first event of the folding is formation of hydrogen bonds and the second is that of the hydrophobic core, or vice versa. 相似文献
72.
Toshio Kurobori Tetsu Kitao Yukio Hirose Ken-ichi Kawamura Daijyu Takamizu Masahiro Hirano Hideo Hosono 《Radiation measurements》2004,38(4-6):759-762
We report a new technique to fabricate both laser-active F2 and F3+ colour centres in lithium fluoride and permanent periodic gratings with fringe spacings as fine as sub-micron size simultaneously by two interfering infrared femtosecond (fs) laser pulses. In particular, the optical properties of such colour centres produced by a single fs laser pulse are compared with those created by damage from radiation such as X-rays. Moreover, the present technique is applied to the first production of three-dimensional active channel waveguide and a pulsed distributed-feedback (DFB) laser at around 700 nm in LiF containing F2 colour centres with fine-pitched micro-grating structures. 相似文献
73.
We study the q-difference analogue of the sixth Painlevé equation (q-PVI) by means of tau functions associated with the affine Weyl group of type D5. We prove that a solution of q-PVI coincides with a self-similar solution of the q-UC hierarchy. As a consequence, we obtain in particular algebraic solutions of q-PVI in terms of the universal character which is a generalization of the Schur polynomial attached to a pair of partitions. 相似文献
74.
A TiO2-coated indium tin oxide electrode was further coated with Ni(OH)2 by electrodeposition to obtain a TiO2-Ni(OH)2 bilayer film. Upon irradiation of the bilayer film with UV light in a pH 10 buffer, the Ni(OH)2 layer was oxidized, and it turned from colorless to brown; oxidative energy was stored in the layer. The potential of the oxidative energy thus stored was about +0.7 V versus Ag|AgCl. The stored energy could be reversibly taken out of the film by chemical and electrochemical means. The photooxidized Ni(OH)2 was rereduced by alcohols, aldehydes, phenol, I-, H2O2, formate, and acetone. 相似文献
75.
Nunokawa K Ito M Sunahara T Onaka S Ozeki T Chiba H Funahashi Y Masuda H Yonezawa T Nishihara H Nakamoto M Yamamoto M 《Dalton transactions (Cambridge, England : 2003)》2005,(16):2726-2730
New mixed metal clusters with M19 metal frameworks have been synthesized by NaBH4 reduction of Au(NO3)(PMe2Ph) together with AgNO3 in ethanol. Single crystal X-ray diffraction has revealed Au12Ag7 and Au17Ag2 metal skeletons for these clusters, which are best described in terms of bicapped pentagonal antiprismatic cages with a staggered-staggered M(5) ring configuration. These clusters connect the missing link between M13 icosahedral and M25 biicosahedral clusters providing a view of the cluster growth process. A TEM image of this cluster has been observed, which has clearly demonstrated single-sized nano-particles of less than 1.0 nm. 相似文献
76.
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78.
Quyen Thi le Nguyen Maiko Okajima Tetsu Mitsumata Kai Kan Hang Thi Tran Tatsuo Kaneko 《Colloid and polymer science》2012,290(2):163-172
Anionic polysaccharide (PS) was extracted from Aphanothece stagnina biomaterials where trivalent metal ions were remarkably condensed from environmental water. Structural analyses indicated
that the PS was considered to be a kind of sulfated rhamnoglucan-containing uronic acid at a composition of 23 mol% and that
the total composition of anionic groups such as sulfate and carboxylate was 31 mol% to the monosaccharide residues. Since
the PS was found to be a huge macromolecule with an ultra-high molecular weight (3.14 × 107 g/mol), the simple calculation indicated that about 9.5 × 104 anions exist on one chain of the PS. The electric conductivity of the highly anionic PS solutions indicated that the metal
ions such as Ga3+, La3+, and Ca2+ complexed ionically with PS chains. The PS formed the gels as a result of trivalent metal complexation, but the gelation
behavior of the PS was different from that of the representative metal-complexable polysaccharide, alginate, in terms of the
minimum gel formation concentration and the average molecular weight between cross-linking points. 相似文献
79.
Hiroshi Suzuki Tetsu Itotagawa Yuli Setyo Indartono Hiromoto Usui Norihide Wada 《Rheologica Acta》2006,46(2):287-295
Rheological characteristics of trimethylolethane (TME) clathrate–hydrate slurry treated with drag-reducing surfactants were investigated. Friction coefficients and apparent viscosities were measured when the concentration of TME and its hydrate fraction treated with and without drag-reducing surfactants were changed in several steps. From the results, it is found that the surfactant addition causes effective drag reduction in a pipe flow when the hydrate fraction becomes high, while effective drag reduction disappears in the cases of low hydrate fraction. The results of viscosity measurements indicate that the TME molecules disturb the formation of shear-induced structures (SIS) causing drag reduction phenomena. To investigate this interaction between TME and surfactant micelles, the effect of TME concentration on viscosity and relaxation time of solutions was discussed. From this, it was found out that there exists a critical concentration of TME on the formation of SIS and that it becomes larger as shear rate increases. Thus, we conclude that this interaction between TME and micellar structures causes less drag reduction for the cases of low hydrate fraction, while the drag reduction appears in cases of high hydrate fraction because TME concentration in liquid phase becomes small. 相似文献
80.
Masahiro Yoshida Kenji Ishii Ignace Jarrige Tetsu Watanuki Kazutaka Kudo Yoji Koike Ken'ichi Kumagai Nozomu Hiraoka Hirofumi Ishii Ku‐Ding Tsuei Jun'ichiro Mizuki 《Journal of synchrotron radiation》2014,21(1):131-135
A single‐crystal momentum‐resolved resonant inelastic X‐ray scattering (RIXS) experiment under high pressure using an originally designed diamond anvil cell (DAC) is reported. The diamond‐in/diamond‐out geometry was adopted with both the incident and scattered beams passing through a 1 mm‐thick diamond. This enabled us to cover wide momentum space keeping the scattering angle condition near 90°. Elastic and inelastic scattering from the diamond was drastically reduced using a pinhole placed after the DAC. Measurement of the momentum‐resolved RIXS spectra of Sr2.5Ca11.5Cu24O41 at the Cu K‐edge was thus successful. Though the inelastic intensity becomes weaker by two orders than the ambient pressure, RIXS spectra both at the center and the edge of the Brillouin zone were obtained at 3 GPa and low‐energy electronic excitations of the cuprate were found to change with pressure. 相似文献