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881.
Tomokazu Ito Akihiko Nakatsuka Hideki Maekawa Akira Yoshiasa Takamitsu Yamanaka 《无机化学与普通化学杂志》2000,626(1):42-49
The crystal structures of MgAl2–xGaxO4 (0 ≤ x ≤ 2) spinel solid solutions (x = 0.00, 0.38, 0.76, 0.96, 1.52, 2.00) were refined using 27Al MAS NMR measurements and single crystal X‐ray diffraction technique. Site preferences of cations were investigated. The inversion parameter (i) of MgAl2O4 (i = 0.206) is slightly larger than given in previous studies. It is considered that the difference of inversion parameter is caused by not only the difference of heat treatment time but also some influence of melting with a flux. The distribution of Ga3+ is little affected by a change of the temperature from 1473 K to 973 K. The degree of order‐disorder of Mg2+ or Al3+ between the fourfold‐ and sixfold‐coordinated sites is almost constant against Ga3+ content (x) in the solid solution. A compositional variable of the Ga/(Mg + Ga) ratio in the sixfold‐coordinated site has a constant value through the whole compositional range: the ratio is not influenced by the occupancy of Al3+. The occupancy of Al3+ is independent of the occupancy of Ga3+, though it depends on the occupancy of Mg2+ according to thermal history. The local bond lengths were estimated from the refined data of solid solutions. The local bond length between specific cation and oxygen corresponds with that expected from the effective ionic radii except local Al–O bond length in the fourfold‐coordinated site and local Mg–O bond length in the sixfold‐coordinated site. The local Al–O bond length in the fourfold‐coordinated site (1.92 Å) is about 0.15 Å longer than the expected bond length. This difference is induced by a difference in site symmetry of the fourfold‐coordinated site. The nature that Al3+ in spinel structure occupies mainly the sixfold‐coordinated site arises from the character of Al3+ itself. The local Mg–O bond length in the sixfold‐coordinated site (2.03 Å) is about 0.07 Å shorter than the expected one. Difference Fourier synthesis for MgGa2O4 shows a residual electron density peak of about 0.17 e/Å3 in height on the center of (Ga0.59 Mg0.41)–O bond. This peak indicates the covalent bonding nature of Ga–O bond on the sixfold‐coordinated site in the spinel structure. 相似文献
882.
Kenzo Inoue Hidehito Miyamoto Tomoyuki Itaya 《Journal of polymer science. Part A, Polymer chemistry》1997,35(9):1839-1847
Novel multiarmed polymers with ethylene oxide units, [( CH2CH2O)n : 7, n = 3; 8, n= 7.2; 9, n = 11.8, and 12, n = 11.8] were prepared from the reaction of polyethylene glycol monomethyl ethers with acid chlorides of hexakis(3,5-dicarboxyphenoxy)-( 6 ) and hexakis(4-carboxyphenoxy)cyclotriphosphazenes ( 11 ) and conductivities of their Li+ salt complexes were investigated. The glass transition temperatures of the salt-free polymers are in the temperature range −59 to −54°C, indicative of a high degree of reorientational mobility of the arms. When LiClO4 was added to the multiarmed polymers, the Tg values raised monotonically. The extent of Tg elevation was affected by the length of arms and the number of oxygen atoms around cyclotriphosphazene core and increased in the order 7 > 8 > 12 > 9 . The conductivities increased in the order 9 > 8 = 12 > 7 and the maximum conductivities of 4.0 × 10−5 S/cm at 30°C and 6.0 × 10−4 S/cm at 90°C have been achieved for the 9 -Li+ complex with Li+/O = 0.03. Interestingly, the conductivity of 9 -Li+ complexes at constant reduced temperatures increased in the whole concentrations of LiClO4 examined (Li+/O = 0.01–0.2), although the degree of increase in conductivity above Li+/O = 0.06 became small. From the behaviors of Tg and the conductivity of multiarmed polymer–LiClO4 complexes, it appears that the conductivity is governed by relative concentrations of inter- and intramolecular complexes in the polymer matrix. The influence of structural change of the comb-shaped to multiarmed polymers on the conductivity is described. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1839–1847, 1997 相似文献
883.
Keiichiro Sugimoto Midori Amako Hiroaki Takeuchi Kazuya Nakagawa Morio Yoshimura Yoshiaki Amakura Tomoyuki Fujita Shigeo Takenaka Hiroshi Inui 《Molecules (Basel, Switzerland)》2022,27(1)
Inhibition of fructose absorption may suppress adiposity and adiposity-related diseases caused by fructose ingestion. Eucalyptus leaf extract (ELE) inhibits intestinal fructose absorption (but not glucose absorption); however, its active compound has not yet been identified. Therefore, we evaluated the inhibitory activity of ELE obtained from Eucalyptus globulus using an intestinal fructose permeation assay with the human intestinal epithelial cell line Caco-2. The luminal sides of a cell monolayer model cultured on membrane filters were exposed to fructose with or without the ELE. Cellular fructose permeation was evaluated by measuring the fructose concentration in the medium on the basolateral side. ELE inhibited 65% of fructose absorption at a final concentration of 1 mg/mL. Oenothein B isolated from the ELE strongly inhibited fructose absorption; the inhibition rate was 63% at a final concentration of 5 μg/mL. Oenothein B did not affect glucose absorption. In contrast, the other major constituents (i.e., gallic acid and ellagic acid) showed little fructose-inhibitory activity. To our knowledge, this is the first report that oenothein B in ELE strongly inhibits fructose absorption in vitro. ELE containing oenothein B can prevent and ameliorate obesity and other diseases caused by dietary fructose consumption. 相似文献
884.
Eishun Tsuchida Teruyuki Komatsu Yasuko Mastukawa Tomoyuki Okada 《Macromolecular Symposia》2002,186(1):1-6
Incorporation of different structured synthetic hemes, 5,10,15,20-tetraphenylporphyrinatoiron(II) derivetives with a covalently linked proximal base [FeP( 1 ) to FeP( 7 )], into human serum albumin (HSA), provides seven types of albumin-heme hybrids (HSA-FeP) with different O2-binding abilities. An HSA host absorbs a maximum of eight FeP molecules in each case. The obtained all HSA-FePs can reversibly bind and release O2 under physiological conditions (in aqueous media, pH 7.3, 37°C) as similar as hemoglobin and myoglobin. The difference in the fence structures did not affect the O2-binding parameters, however the axial histidine coordination significantly increased the O2-binding affinity, which is ascribed to the low O2-dissociation rate constants. The most remarkable effect of the heme structure appeared in the half-lifetime (τ1/2) of the O2-adduct complex. The dioxygenated rHSA-FeP( 4 ) showed an unusually long lifetime (τ1/2: 25 hr at 37°C) which is ca. 13-fold longer than that of rHSA-FeP( 1 ). 相似文献
885.
5-(4-Trimethylsilyethynylphenyl)-10,15,20-triphenylplatinumporphyrin was synthesized and copolymerized with trimethylsilylpropyne to give a new high-molecular-weight porphyrin polymer. The polymer formed a smooth and tough coating on many types of surfaces. The coating showed a strong blue luminescence from the platinumporphyrin residue which was quenched in the presence of oxygen. The relationship of the luminescence intensity vs oxygen pressure displayed a remarkably high pressure sensitivity in the low oxygen pressure area, which was ascribed to the high oxygen permeability of the polymer. 相似文献
886.
Jun Manabe Nagisa Sako Mizuki Ito Dr. Masaru Fujibayashi Dr. Chisato Kato Dr. Goulven Cosquer Prof. Katsuya Inoue Dr. Kiyonori Takahashi Prof. Takayoshi Nakamura Prof. Tomoyuki Akutagawa Dr. Seiya Shimono Dr. Hiroki Ishibashi Prof. Yoshiki Kubota Prof. Sadafumi Nishihara 《欧洲无机化学杂志》2023,26(34):e202300449
Materials exhibiting irreversible phase transitions, leading to changes in their properties, have a potential for novel application in electronic components such as a non-rewritable high-security memory. Here, we focused on the two salts, [(9-triptycylammonium)([18]crown-6)][Ni(dmit)2] ( 1 ) and [(9-triptycylammonium)([15]crown-5)][Ni(dmit)2] ( 2 ), which featured 2D sheet structures with alternately stacked cation and anion layers. Both salts exhibit similar cation arrangements, however, their anion arrangements differ significantly. The temperature-dependent magnetic susceptibilities of 1 and 2 were well reproduced by the alternating chain model (JAC1/kB=−306(8), JAC2/kB=−239(3) K) and the Curie-Weiss model (θ=−3.9(1) K), respectively. 1 experience a reversible phase transition around 40–60 K, causing anomalies in magnetic behavior. Moreover, an irreversible single-crystal-to-single-crystal phase transition to 1′ undergo at ~381 K, inducing a rearrangement of [Ni(dmit)2]− anions and a resistivity decrease from 6.5×106 to 6.5×102 Ω cm. The susceptibility curve of 1′ was reproduced by a combination of the Curie-Weiss and dimer models (Jdimer/kB=−407(5), θ=−26.7(5) K). The irreversible transition of 1 is the first example for such supramolecule and [Ni(dmit)2]− system to our knowledge, in opening potential new-type materials. 相似文献
887.
Dr. Wei Zheng Dr. Kosuke Oki Dr. Ranajit Saha Dr. Yuh Hijikata Prof. Eiji Yashima Dr. Tomoyuki Ikai 《Angewandte Chemie (International ed. in English)》2023,62(11):e202218297
Defect-free one-handed contracted helical tubular ladder polymers with a π-electron-rich cylindrical helical cavity were synthesized by alkyne benzannulations of the random-coil precursor polymers containing 6,6′-linked-1,1′-spirobiindane-7,7′-diol-based chiral monomer units. The resulting tightly-twisted helical tubular ladder polymers showed remarkably high enantioseparation abilities toward a variety of chiral hydrophobic aromatics with point, axial, and planar chiralities. The random-coil precursor polymer and analogous rigid-rod extended helical ribbon-like ladder polymer with no internal helical cavity exhibited no resolution abilities. The molecular dynamics simulations suggested that the π-electron-rich cylindrical helical cavity formed in the tightly-twisted tubular helical ladder structures is of key importance for producing the highly-enantioseparation ability, by which chiral aromatics can be enantioselectively encapsulated by specific π-π and/or hydrophobic interactions. 相似文献
888.
Prof. Ming-Shui Yao Prof. Ken-ichi Otake Jiajia Zheng Masahiko Tsujimoto Dr. Yi-Fan Gu Lu Zheng Dr. Ping Wang Dr. Shivanna Mohana Dr. Mickaele Bonneau Tomoyuki Koganezawa Tetsuo Honma Hirotaka Ashitani Shogo Kawaguchi Prof. Yoshiki Kubota Prof. Susumu Kitagawa 《Angewandte Chemie (International ed. in English)》2023,62(35):e202308990
A one-stone, two-bird method to integrate the soft porosity and electrical properties of distinct metal–organic frameworks (MOFs) into a single material involves the design of conductive-on-insulating MOF (cMOF-on-iMOF) heterostructures that allow for direct electrical control. Herein, we report the synthesis of cMOF-on-iMOF heterostructures using a seeded layer-by-layer method, in which the sorptive iMOF core is combined with chemiresistive cMOF shells. The resulting cMOF-on-iMOF heterostructures exhibit enhanced selective sorption of CO2 compared to the pristine iMOF (298 K, 1 bar, S from 15.4 of ZIF-7 to 43.2–152.8). This enhancement is attributed to the porous interface formed by the hybridization of both frameworks at the molecular level. Furthermore, owing to the flexible structure of the iMOF core, the cMOF-on-iMOF heterostructures with semiconductive soft porous interfaces demonstrated high flexibility in sensing and electrical “shape memory” toward acetone and CO2. This behavior was observed through the guest-induced structural changes of the iMOF core, as revealed by the operando synchrotron grazing incidence wide-angle X-ray scattering measurements. 相似文献
889.