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121.
Nishikawa T Koide Y Kajii S Wada K Ishikawa M Isobe M 《Organic & biomolecular chemistry》2005,3(4):687-700
The total synthesis of alpha-C-mannosyltryptophan (C-Man-Trp), a naturally occurring C-glycosylamino acid, was achieved from a commercially available alpha-methyl-D-mannoside in 10 steps including the following key steps: the C-glycosidation of a mannose derivative with a stannylacetylene, Castro indole synthesis, and Sc(ClO4)3-promoted coupling with L-serine-derived aziridine carboxylate. The glucose- and galactose-analogues of C-Man-Trp were also synthesized in a similar manner. Conformational analyses of the synthesized C-glycosyltryptophan and its synthetic intermediate are briefly discussed. 相似文献
122.
Matsuoka M Segawa J Amimoto I Masui Y Tomii Y Kitano M Kise M 《Chemical & pharmaceutical bulletin》1999,47(12):1765-1773
A series of 7-substituted-6-fluoro-1-fluoromethyl-4-oxo-4H- [1,3]thiazeto[3,2-a]quinoline-3-carboxylic acid derivatives (2a-1) was prepared and evaluated for antibacterial activity. These compounds were obtained by deacylation of 4-benzoyloxy-2-(1-chloro-2-fluoroethyl)thio-6,7- difluoroquinoline-3-carboxylate (10) and subsequent intramolecular cyclization followed by substitution with cyclic amines and then hydrolysis. The intramolecular cyclization reaction of 18, one of the diastereomers (17, 18) revealed that the cyclization reaction proceeded through an inversion to afford (-)-11a in good chemical and optical yield. The enantiomers of 2a were prepared from the enantiomers of 11a, which were obtained by the optical resolution of the racemate using high-performance liquid chromatography (HPLC). Compounds 2a,b showed excellent in vitro and in vivo antibacterial activity against both gram-negative and gram-positive bacteria including quinolone and Methicillin-resistant Staphylococcus aureus. 相似文献
123.
K. Selby M. Vollmer J. Masui V. Kresin W. A. de Heer W. D. Knight 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1989,12(1-4):477-479
Photoabsorption cross sections of small neutral sodium clusters are measured at wavelengths from 452 to 604 nm. We find that surface plasma oscillations of the valence electrons dominate the photoabsorption spectra. The experimental results are consistent with predictions based on an extended Clemenger-Nilsson model, general sum rules, and the experimental static electric polarizabilities. For Na8 a single broad resonance is observed, the peak wavelength is in excellent agreement with the model. The data for Na9 and Na10 support the prediction of double resonances. 相似文献
124.
G. Masui 《The Journal of chemical thermodynamics》2006,38(12):1711-1716
(p, ρ, T) Measurements and visual observations of the meniscus for isobutane were carried out carefully in the critical region over the range of temperatures: −15 mK ? (T − Tc) ? 35 mK, and of densities: −7.5 kg · m−3 ? (ρ − ρc) ? 7.5 kg · m−3 by a metal-bellows volumometer with an optical cell. Vapor pressures were also measured at T = (310, 405, 406, 407, and 407.5) K. The critical point of Tc and ρc was determined by the image analysis of the critical opalescence which is proposed in this study. The critical pressure pc was determined to be the pressure measurement at the critical point. Comparisons of the critical parameters with values given in the literature are presented. 相似文献
125.
Optical waveguide spectroscopy was used under non-contact conditions to analyze the visible absorption spectrum of poly(ethylene oxide) (M w = 150) modified cytochrome c (PEO150-cyt.c) adsorbed on an indium tin oxide (ITO) glass electrode. The redox reactions of the adsorbed PEO150-cyt.c were dynamically measured in situ in PEO oligomers (M w = 200). It was confirmed that PEO modification of cyt.c is effective in maintaining the redox activity of the cyt.c after adsorption on the ITO glass electrode. The PEO150-cyt.c adsorbed on the electrode re-dissolved gradually in PEO oligomer. Against this, PEO1000-cyt.c having longer PEO chains (M w = 1000) was found to be adsorbed stably on the electrode. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
126.
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128.
Fujita K Nakamura N Ohno H Leigh BS Niki K Gray HB Richards JH 《Journal of the American Chemical Society》2004,126(43):13954-13961
Well-defined voltammetric responses of redox proteins with acidic-to-neutral pI values have been obtained on pure alkanethiol as well as on mixed self-assembled-monolayer (SAM) omega-derivatized alkanethiol/gold bead electrodes. Both azurin (P. aeruginosa) (pI = 5.6) and subunit II (Cu(A) domain) of ba(3)-type cytochrome c oxidase (T. thermophilus) (pI = 6.0) exhibit optimal voltammetric responses on 1:1 mixtures of [H(3)C(CH(2))(n)()SH + HO(CH(2))(n)()SH] SAMs. The electron transfer (ET) rate vs distance behavior of azurin and Cu(A) is independent of the omega-derivatized alkanethiol SAM headgroups. Strikingly, only wild-type azurin and mutants containing Trp48 give voltammetric responses: based on modeling, we suggest that electronic coupling with the SAM headgroup (H(3)C- and/or HO-) occurs at the Asn47 side chain carbonyl oxygen and that an Asn47-Cys112 hydrogen bond promotes intramolecular ET to the copper. Inspection of models also indicates that the Cu(A) domain of ba(3)-type cytochrome c oxidase is coupled to the SAM headgroup (H(3)C- and/or HO-) near the main chain carbonyl oxygen of Cys153 and that Phe88 (analogous to Trp143 in subunit II of cytochrome c oxidase from R. sphaeroides) is not involved in the dominant tunneling pathway. Our work suggests that hydrogen bonds from hydroxyl or other proton-donor groups to carbonyl oxygens potentially can facilitate intermolecular ET between physiological redox partners. 相似文献
129.
Y Nishioka S Kyotani H Masui M Okamura M Miyazaki K Okazaki S Ohnishi Y Yamamoto K Ito 《Chemical & pharmaceutical bulletin》1989,37(11):3074-3077
Cisplatin (CDDP) containing albumin microspheres and microcapsules incorporating biodegradable macromolecules, chitin and chitosan, were prepared, and their CDDP content and releasing ability and susceptibility to various enzymes were examined. Chitin was incorporated during preparation of the microspheres, while chitosan was used to treat preformed microspheres. CDDP content was remarkably increased by chitin; when chitin was incorporated at a concentration of 1.5%, the CDDP content of the microspheres was found to be 16.2% (1.8 times that with no addition of chitin). CDDP release was suppressed by chitin and chitosan. The 50% CDDP release time was about 1.5 h when no chitin was added, but about 16 h was required when chitin was incorporated into the microspheres at a concentration of 1.5%. Chitin and chitosan suppressed the decomposition by protease. The microspheres treated with 70% deacetylated chitosan showed the greatest susceptibility to lysozyme. In conclusion, CDDP release can be controlled by the use of chitin or chitosan, and the microspheres should show no immunogenicity in vivo because of their susceptibility to lysozyme. 相似文献
130.
Yamaguchi M Kumano T Masui D Yamagishi T 《Chemical communications (Cambridge, England)》2004,(7):798-799
The chloro(Me(2)SO)ruthenium(II) complexes with tris(2-pyridylmethyl)amine or its derivative catalyses the selective, stereospecific, and photoregulative alkane oxidation in the presence of 2,6-dichloropyridine N-oxide under visible light irradiation. 相似文献