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81.
Yasuto Tsuruta Hirofumi Inoue Keiko Fukunaga Sayaka Munemura Misa Ozaki Masaya Ohta Fumito Matsuura 《Analytical sciences》2005,21(6):697-699
A highly sensitive method for the determination of bisphenol-A in water with semi-micro column high-performance liquid chromatography using 2-methoxy-4-(2-phthalimidinyl)phenylsulfonyl chloride as a fluorescent labeling reagent has been developed. The labeling reaction was carried out at 70 degrees C for 20 min in borate buffer (pH 9.5). The derivative eluted at 11.6 min on a reversed-phase column with methanol-water (78:22, v/v) at a flow-rate of 0.2 ml/min. The fluorescence was monitored at 308 nm for excitation and 410 nm for emission. The detection limit (S/N = 3) was 10 fmol per injection. The labeling yield was about 95%. 相似文献
82.
Specific swelling behaviors of alkali‐metal poly(styrene sulfonate) gels in aqueous solvent mixtures
Yoko Fukunaga Mariko Hayashi Mitsuru Satoh 《Journal of Polymer Science.Polymer Physics》2007,45(10):1166-1175
Counterion‐ and solvent‐specific swelling behaviors were investigated for alkali‐metal poly(styrene sulfonate) (PSSM) gels having different degrees of sulfonation in aqueous organic solvent mixtures [water plus methanol, ethanol, 2‐propyl alcohol, t‐butyl alcohol, dimethyl sulfoxide (DMSO), acetone, acetonitrile, tetrahydrofuran, or dioxane]. With an increasing organic solvent concentration, most gel systems, except for DMSO, showed a volume phase transition. The transition abruptly occurred without significant deswelling in the lower solvent concentration region. Such swelling behavior contrasted with that of other common charged gel systems, including alkali‐metal polyacrylate (PAAM) gels, which showed gel collapse after gradual deswelling with an increasing organic solvent concentration. The dielectric constant at the critical transition point (Dcr) for most mixed solvent systems decreased in the order of PSSK ≥ PSSCs ≥ PSSNa > PSSLi; that is, larger counterion systems were favorable for the transition. The counterion specificity also contrasted with our previous results for PAAM gels: PAANa > PAAK > PAALi ~ PAACs. On the other hand, the solvent specificity for the PSSM gels was similar to that for the PAAM gels; the higher the dielectric constant was of the organic solvent, the higher the Dcr value was at which the transition occurred. These specificities were examined on the basis of the solvation properties of the counterions and polymer charged groups and the solvent properties such as the Gutmann–Mayer donor number and acceptor number. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1166–1175, 2007 相似文献
83.
Kazuhiro Mori Toshiharu Fukunaga Masaaki Sugiyama Kenji Iwase Koji Oishi Osamu Yamamuro 《Journal of Physics and Chemistry of Solids》2012,73(11):1274-1277
For Low Heat Cement (LHC), its hydration reaction properties and compressive strength development were studied by quasi-elastic neutron scattering (QENS) and compressive strength test. In the QENS experiments, the amount of hydration products was estimated and the hydration behavior of LHC was revealed in the early hydration times of 7 days. Simultaneously, we compared the compressive strength of a mortar specimen made from LHC with the amount of hydration products. It was found that the compressive strength is strictly proportional to the amount of hydration products in the range from 15 h to 7 days of hydration. 相似文献
84.
Hiroki Fukunaga Dr. Wataru Kosaka Honoka Nemoto Dr. Kouji Taniguchi Dr. Shogo Kawaguchi Dr. Kunihisa Sugimoto Prof. Dr. Hitoshi Miyasaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(70):16755-16766
The insertion of “sandwiched spins” between magnetic layers could efficiently affect the interlayer magnetic correlations, but doing so increases the complexity in the interlayer spin alignment because of competition between the inserted spin-layer interaction JNNI and the interlayer through-space interaction JNNNI if the magnitude of JNNI is of the same order as JNNNI with reciprocal signs of the respective interactions. Herein, systematic tuning of the magnetic phase variations by JNNI and JNNNI in two kinds of metal-variable isostructural series of supramolecular pillared layer magnets [MCp*2][{Ru2II,II(2,3,5,6-F4CO2)4}2(TCNQ)] ⋅ 2 DCE (M=Co, Fe, Cr; 2,3,5,6-F4PhCO2−=2,3,5,6-tetrafluorobenzoate; TCNQ=7,7,8,8-tetracyano-p-quinodimethane; DCE=1,2-dichloroethane) and their DCE-free series, in which [MCp*2]+ (Cp*=η5-C5Me5) species with S=0, 1/2, and 3/2 for M=Co, Fe, Cr, respectively, are sandwiched between ferrimagnetic layers of [{Ru2}2(TCNQ)]−, is demonstrated. The results showed that the flexible magnetic natures of these magnets are changeable in dependence on JNNI and JNNNI, as well as on interlayer inserted spins M. 相似文献
85.
Taisuke Matsuno Kengo Fukunaga Sota Sato Hiroyuki Isobe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(35):12298-12302
Upon encapsulating an oval‐shaped hydrocarbon guest, a cylindrical host deforms its shape to maximize intermolecular contacts. Structure–assembly relationship studies with a series of hydrocarbon guests disclosed the importance of molecular shapes and CH–π contacts. Multiple contacts and weak CH–π hydrogen bonds resulted in an optimal assembly; however, the shape deformation resulted in severe retardation of rotational motions in the crystal. Thus, unlike a circular guest, the oval‐shaped guest did not change its orientation in the host. Unexpectedly, the planar guest did not affect the packing structure to form a double helix in intertwined host arrays. 相似文献
86.
Determination of ASP3258, a novel phosphodiesterase type 4 inhibitor,in rat plasma by high‐performance liquid chromatography with fluorescence detection and its application to pharmacokinetic study
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Yoshiaki Ohtsu Fumiyo Takanuki Yasuhisa Fukunaga Kiyoshi Noguchi 《Biomedical chromatography : BMC》2015,29(2):161-163
The potent phosphodiesterase 4 inhibitor ASP3258 contains a carboxylic acid moiety and a naphthyridine ring and is a novel therapeutic agent for asthma and chronic obstructive pulmonary disease. To support the drug development of ASP3258, we developed and validated a simple method for its determination in rat plasma. Following the addition of the analog AS1406604‐00 as an internal standard, plasma samples were processed using C18‐bonded solid‐phase extraction cartridges under acidic conditions and injected into a high‐performance liquid chromatography system with fluorescence detection. Chromatographic separation was achieved on a Shiseido Capcell Pak C18 UG120 column (3.0 × 150 mm, 5 µm) with a mobile phase consisting of acetonitrile–0.5% acetic acid (50:50, v/v). HPLC eluent was monitored with a fluorescence detector set at a wavelength of 315 nm for excitation and 365 nm for emission. The calibration curve was linear over a range of 2.5–250 ng/mL. Validation data demonstrated that the method is selective, sensitive and accurate. In addition, the present method was successfully applied to rat plasma samples from a pharmacokinetic study. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
87.
Neutron and X-ray diffraction measurements were performed to investigate the structure of Na2S–GeS2 glasses synthesized by mechanical alloying. The Ge–S coordination numbers calculated from the total correlation functions show that GeS4 tetrahedra form the basic framework structure of Na2S–GeS2 glasses. In addition, a three-dimensional structural model of the (Na2S)50(GeS2)50 glass was obtained by using reverse Monte Carlo (RMC) simulation on neutron and X-ray diffraction data, and it was compared with the RMC model previously obtained for a (Li2S)50(GeS2)50 glass. The results show that the Ge–S framework structures in the two glasses are almost the same in the short and intermediate ranges; that is, the Ge–S framework structures are formed mainly by the connection of corner-sharing GeS4 tetrahedra. Many of the Na ions are coordinated by four S atoms, which are non-bridging S atoms and/or bridging S atoms. 相似文献
88.
Shuichi Wakimoto Hiroyuki Kimura Mamoru Fukunaga Keisuke Nishihata Masayasu Takeda Kazuhisa Kakurai Yukio Noda Yoshinori Tokura 《Physica B: Condensed Matter》2009,404(17):2513
Polarized neutron diffraction experiments have been performed on multiferroic materials RMn2O5 (R=Ho, Er) under electric fields in the ferroelectric commensurate (CM) and the low-temperature incommensurate (LT-ICM) phases, where the former has the highest electric polarization and the latter has reduced polarization. It is found that, after cooling in electric fields down to the CM phase, the magnetic chirality is proportional to the electric polarization. Also we confirmed that the magnetic chirality can be switched by the polarity of the electric polarization in both the CM and LT-ICM phases. These facts suggest an intimate coupling between the magnetic chirality and the electric polarization. However, upon the transition from the CM to LT-ICM phase, the reduction of the electric polarization is not accompanied by any reduction of the magnetic chirality, implying that the CM and LT-ICM phases contain different mechanisms of the magnetoelectric coupling. 相似文献
89.
Y. Fukunaga M. Harada S. Bandow S. Iijima 《Applied Physics A: Materials Science & Processing》2009,94(1):5-9
Resistivity of pelletized carbon nanohorn particles (CNHs) decreased immediately as the pressure for making the pellet increased.
This behavior can be fitted by a power scaling relation with quasi-2-dimensional percolating conducting channels. Similarly,
the resistivity of a pelletized boron-doped CNHs (B-CNHs) also decreased rapidly as a function of boron concentration in the
region of low boron contents (<∼0.5%). On the other hand, the characteristic temperature for variable range hopping (VRH)
conduction indicated different behavior, showing almost constant values for pristine CNHs and drastic changes for B-CNHs.
By analyzing these experimental results using VRH theory it was found that the resistivity drop for B-CNHs can be explained
by the increase of the electronic density of states at the Fermi level of nanohorns due to substitutional doping of boron
in the sp2 bonded carbon network which is unlike the percolation for pristine CNHs. 相似文献
90.
Polarized Raman spectra are investigated in GeSe and SnSe at low temperatures. New Raman lines which can not be expected by a group theoretical analysis for the known crystal structure of the orthorhombic D162h have been observed typically in the (a, a) and (b, b) polarization configurations. With decreasing temperature, three lines in GeSe grow weakly at 89,201 and strongly at 226 cm-1 below 150 K, accompanied by enhancement of layer breathing mode (175 cm-1 at 273 K) intensity. One line in SnSe grows weakly at 193 cm-1 below 50 K. The appearance of the new Raman lines as well as a resistivity anomaly suggests a novel structural phase transition in this system. 相似文献