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251.
Nakamura T Miyamae T Nakai I Kondoh H Kawamoto T Kobayashi N Yasuda S Yoshimura D Ohta T Nozoye H Matsumoto M 《Langmuir : the ACS journal of surfaces and colloids》2005,21(8):3344-3353
Organic ditellurides (R2Te2 where R = n-butyl (C4), n-octyl (C8), and n-cetyl (C16)) were synthesized, and their adsorption states after oxidation on Au(111) surfaces were studied by X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), theoretical analyses, near-edge X-ray absorption fine structure (NEXAFS) measurements, contact angle measurements, and atomic force microscopy (AFM). The obtained results show that dialkyl ditellurides form autooxidized monolayers (AMs) on the surfaces under ambient conditions and that the oxidation process is accelerated by ambient light. XPS, UPS, and theoretical analyses suggest that the autooxidized ditelluride species consist of polymers or oligomers with Te-O-Te-O network structures stabilized by oxygen bridges between tellurium molecules following the cleavage of tellurium-gold bonds. NEXAFS and contact angle measurements indicate that the average tilt angles of the alkyl chains from the surface normal are smaller for the AMs of dialkyl ditellurides having longer alkyl chains. AFM measurements show defects and roughness features around a few angstroms in height on the surfaces of the dialkyl ditelluride AMs. 相似文献
252.
Akihiro Ito Tooru Ooya Nobuhiko Yui 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):233-236
A polypseudorotaxane was prepared using 4-(N,N-dimethylamino) benzoyl modified β-cyclodextrin (DMAB-β-CD) and biotin-terminated poly(propylene glycol) (biotin-terminated
PPG) in water for 7 days. When the biotin-terminated PPG was added to a saturated solution of DMAB-β-CD at room temperature,
the polypseudorotaxane was not obtained. However, with increasing temperature to 60 °C, precipitation was observed. The 1H-NMR spectrum indicated that the obtained precipitate was the polypseudorotaxane. The final yield was 54%, which was higher
than that previously reported for polypseudorotaxane formation using chemically modified β-CD. The polypseudorotaxane can
be useful to make a polyrotaxane via avidin–biotin molecular recognition using the terminal biotin group. 相似文献
253.
beta-Cyclodextrin-conjugated poly(epsilon-lysine) (beta-CDPL) was synthesized as a novel polymeric host for constructing a smart supramolecular assembling system. Systematic studies on the inclusion complexation between the polymeric host with an alpha- or beta-CD cavity and a model guest molecule provided evidence that dual cooperative interactions, specific host-guest interaction and intermolecular ionic interaction, played a dominant role in leading to a fast aggregation phenomenon. In addition, a rapid phase transition induced by the supramolecular assembly was observed reversibly in response to a small change in pH or temperature. 相似文献
254.
Thermal lensing spectrophotometry is applied to the determination of iron(II) with 4,7-diphenyl-1,10-phenanthroline disulfonic acid in aqueous solution, and in chloroform by ion-pair extraction with trioctylmethylammonium chloride. A phase-sensitive detection system with digital processing was used, the optimum modulation frequency being 5–10 Hz. A baseline drift of 0–03% was achieved. In water, the enhancement factor (sensitivity relative to conventional spectrophotometry) was 70 at an exciting power of 800 mW, and 2 × 10-9 M iron(II) was determined. In chloroform 2 × 10-10 M iron(II)—complex could be detected, the enhancement factor being 1200. 相似文献
255.
Sadayuki Koizumi T. Imato Nobuhiko Ishibashi 《Analytical and bioanalytical chemistry》1997,357(1):37-43
Potentiometric selectivities of a plasticized poly(vinyl chloride) (PVC) membrane containing a hydrophobic quaternary ammonium
salt and triphenyltin chloride (TPTCl) for several inorganic anions were evaluated by measurements of the membrane potential
of a bi-ionic system (the so-called bi-ionic membrane potential). The addition of TPTCl to the plasticized PVC membrane containing
a quaternary ammonium salt gave rise to selectivity patterns different from the Hofmeister anion series, which is observed
for a membrane containing only the quaternary ammonium salt. The change in the selectivity pattern from the Hofmeister to
the non-Hofmeister was observed under conditions where the TPTCl concentration was higher than the quaternary ammonium salt
in the membrane. Response mechanisms and the selectivity of the TPTCl-based electrode are discussed with respect to the concentration
dependence of TPTCl and quaternary ammonium salt in the membrane.
Received: 6 July 1995/Revised: 2 February 1996/Accepted: 6 February 1996 相似文献
256.
Toru Takagishi Nobuhiko Kuroki Hiroshi Kozuka Masaru Mitsuishi 《Journal of polymer science. Part A, Polymer chemistry》1985,23(12):3021-3029
The extent of binding of 1-amino-4-alkylaminoanthraquinone-2-sulfonates (alkyl?methyl, ethyl, propyl, and butyl), which have different chemical structures from methyl orange derivatives, by polyion complexes consisting of a piperidinium cationic polymer and various polyanions such as sodium poly acrylate, poly methacrylate, poly styrenesulfonate, carboxymethylcellulose, and dextran sulfate, was measured in an aqueous solution. The effect of alkyl group of the anthraquinone dye on the binding behavior was investigated. Also, the resultant binding characteristics were compared with those previously observed with methyl orange and its homologs. These polyion complexes exhibited very strong binding affinity toward the anthraquinone dye. The polyion complex of the polycation and sodium poly styrenesulfonate bound the dye noncooperatively and the binding process was athermal. The first binding constant accompanying the binding is of the order of 105–106. In contrast, the polyion complexes composed of the polycation and the other polyanions exhibited strong cooperative binding and the binding process was exothermic. The possible mode of binding is discussed. 相似文献
257.
Toru Takagishi Takeo Sugimoto Akiyo Hayashi Nobuhiko Kuroki 《Journal of polymer science. Part A, Polymer chemistry》1983,21(8):2311-2322
Polyethylenimine (PEI) was crosslinked with dichloroethane, glyoxal, or glutaraldehyde and polymers of various degrees of crosslinkage were made. The insoluble polymers obtained were examined for their ability to bind methyl orange and its homologs, methyl, ethyl, propyl, and butyl orange at 5, 15, 25, and 35°C, respectively, in an aqueous solution. PEI crosslinked with glutaraldehyde showed markedly increased binding affinity toward these cosolutes compared with the polymers crosslinked with dichloroethane or glyoxal. The extent of the binding increased with an increase in the degree of crosslinkage. These results suggest that the enhancement of the binding by the crosslinking is due mainly to a dual effect, introduction of hydrophobic moieties and proximity of neighboring polymer chains. The first binding constants and the thermodynamic parameters that accompanied the binding were calculated. The thermodynamic data show that the binding process is athermal and is stabilized entirely by the entropy term. Water-soluble PEI exhibited stronger cooperative interactions than the crosslinked polymer because the mobilities of the chains of the former are greater than those of the latter. 相似文献
258.
Yamauchi M Honda Y Matsuki N Watanabe T Date K Hiramatsu H 《The Journal of organic chemistry》1996,61(8):2719-2725
The Diels-Alder reaction of 1,1-dicarbonylethenes 1 with dienes was investigated. The adduct of the reaction of 1, whose two carbonyl groups were different, with cyclopentadiene showed moderate stereoselectivity and this was explained by FMO theory. However, in the Lewis acid-catalyzed addition, the reaction proceeded with high stereoselectivity to give the exo adduct 3x. This might be due to steric hindrance because the benzene ring cannot orient in the plane of the conjugated system in the metal-chelated enedione 6. Applying this principle to (1'R,2'S,5'R)-5-methyl-2-(1-methyl-1-phenylethyl)cyclohexyl 2-benzoylacrylate (1d), we achieved a diastereomeric Diels-Alder reaction to afford 3x-R, whose structure was confirmed by the X-ray crystal analysis. 相似文献
259.
Katagiri H Iki N Matsunaga Y Kabuto C Miyano S 《Chemical communications (Cambridge, England)》2002,(18):2080-2081
Thiacalix[4]aniline (4), a cyclic tetramer of p-tert-butylaniline bridged with four sulfides, extracted Au(III) and Pd(II) ions specifically from acidic solutions among 41 metal ions including soft metal ions such as Hg(II), Cd(II), Zn(II), Pb(II), and Cu(II). 相似文献
260.
Toru Takagishi Yozo Naoi Ichiro Sonoda Nobuhiko Kuroki 《Journal of polymer science. Part A, Polymer chemistry》1980,18(7):2323-2331
The extent of binding of methvI orange, ethyl orange, propyl orange, and butyl orange by crosslinked polyvinylpyrrolidone was measured in all aqueous Solution. The first binding constants and the thermodynamic parameters accompanying the binding were evaluated. These values were compared with those of water-soluble polyvinylpyrrolidone. The first binding constant, the absolute magnitude of ΔF°, and the value of ΔS° of the crosslinked polyvinylpyrrolidone are substantially larger than those of the water-soluble product for any particular dye. These behaviors can be accounted for in terms of increased hydrophobic domains in the former and enhanced hydrophobic contribution in the binding process. Also the binding of the dye by the crosslinked polymer in a nonaqueous solvent, ethylene glycol, was measured to assess the contribution of hydrophobic interaction to the dye-polymer complex formation in aqueous medium. It was found that the binding of butyl orange by the crosslinked polymer is suppressed in ethylene glycol and the contribution of entropy term to the free energy change in the aqueous environment is large compared with that in ethylene glycol. The significance of the hydrophobic of the hydrophobic interaction in the dye-polymer association process is described. 相似文献