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81.
An analytical method, referred to as "derivatization-electron probe X-ray micro-analysis (XMA)", has been developed to determine the distribution of a small amount of the functional groups in a polymer. The suitable conditions for the derivatization reaction with epoxy groups, which contribute to the hardening reactions of polymers, were investigated. It was found that epoxy groups in polymers were derivatized selectively using gas-phase esterification with hydrochloric acid (HCI). The most suitable amount of HCl in a 50 ml vial was 300 microl. After setting a sample in the vessel without directly contacting the reagent, by reacting the reagent and the sample at 25 degrees C for 1 h, the highest reaction yield and selectivity were obtained. By derivatization-XMA using this reaction condition, the measurement of the distribution of epoxy groups in the polymer became feasible. Actual applications to a depth analysis of epoxy groups in the hardened acrylic coating and epoxy resin proved that this method is useful for the characterization of polymers and for the study of the hardening reaction of polymers. 相似文献
82.
Tetsuji Kametani Hiroo Matsumoto Toshio Honda Mitsuo Nagai Keiichiro Fukumoto 《Tetrahedron》1981,37(15):2555-2560
A stereoselective synthesis of des-A-ring steroids and has been achieved by an intramolecular cycloaddition of 3-isopropenyl-5-(4-methoxybenzocyclobutenyl) pentan-2-one-2-ethylene ketal and 1-(4-methoxy-benzocyclobutenyl)-4-methylpent-4-en-3-ol , respectively. 相似文献
83.
Tetsuji Kametani Ryuko Nitadori Hirohumi Terasawa Keiichi Takahashi Masataka Ihara Keiichiro Fukumoto 《Tetrahedron》1977,33(9):1069-1071
Atheroline (3) an oxoaporphine alkaloid, has been synthesised by photolysis of 8 bromo 1-(3-hydroxy-4-methoxybenzoyl)-6,7-dimethoxyisoquinoline (13) in the presence of sodium hydroxide. 相似文献
84.
Masataka Ihara Keiichiro Fukumoto 《Angewandte Chemie (International ed. in English)》1993,32(7):1010-1022
The one-pot intramolecular double Michael reaction of compounds having two different α, β-unsaturated carbonyl groups to form polycyclic compounds can be carried out by three different methods: in the first the substrate is treated with lithium hexamethyldisilazide, in the second with chlorotrimethylsilane, triethylamine, and zinc chloride at an elevated temperature, and in the third with tert-butyldimethylsilyl trifluoromethanesulfonate and triethylamine. The reaction proceeds with complete regioselectivity and high stereoselectivity following a stepwise mechanism. Spiro-fused bicyclo[2.2.2]octane derivatives can be constructed with high stereoselectivity by the intromolecular double Michael reaction by using the first method. Enantiomerically pure atisine and the enantiomer of atisirene were synthesized stereoselectively by application of this methodology. The syntheses of steroids and angular triquinane-type sesquiterpenoids were possible with the second method. Heterocyclic compounds with a bridgehead nitrogen atom were obtained by the reaction of α, β-unsaturated amides following the second and third methods. The asymmetric synthesis of tylophorine with diastereofacial control was achieved by the intramolecular reaction according to the third method. The sulfur-mediated intramolecular double Michael reaction utilizing the third method produced trans-hydroindane derivatives. Furthermore, the intramolecular Michael-aldol reaction can be employed in synthesizing polycyclic systems with cyclobutane units by treatment with tert-butyldimethylsilyl trifluoromethanesulfonate in the presence of triethylamine. The intermolecular double Michael reaction and related reactions will also be described. 相似文献
85.
Codamine (1) was obtained in 88.4% yield by Eschweiler-Clarke reaction of X with formalin and formic acid, whereas it formed in 46.2% yield in case of Mannich reaction of X with formalin and hydrochloric acid. 相似文献
86.
Ihara M Makita K Fujiwara Y Tokunaga Y Fukumoto K 《The Journal of organic chemistry》1996,61(18):6416-6421
Stereoselective syntheses of tricyclo[5.3.0.0(3,8)]decane 22 and tricyclo[6.3.0.0(3,9)]undecane 26, the basic skeletons of copaborneol and longiborneol, were achieved by the intramolecular double Michael reactions of 2-cyclopenten-1-ones 15-17. The substrates were prepared starting with tricyclo[5.2.1.0(2,6)]deca-4,8-dien-3-one (6). The intramolecular double Michael reactions were carried out under three different conditions: TMSCl-Et(3)N-ZnCl(2), TMSI-(TMS)(2)NH, and Bu(2)BOTf-(TMS)(2)NH. The framework 26 of longiborneol was constructed in good yields using the latter two reagent systems. 相似文献
87.
Masataka Ihara Masahiro Toyota Keiichiro Fukumoto Tetsuji Kametani 《Tetrahedron letters》1984,25(30):3235-3238
Intramolecular double Michael reaction of the α,β-unsaturated enone ester (16), prepared from the dienone (5), stereoselectively gave the tetracyclic product (17), which was converted into the isoatisirene type compound (20). 相似文献
88.
Tetsuji Kametani Keiichiro Fukumoto Hiroshi Kurobe Hideo Nemoto 《Tetrahedron letters》1981,22(37):3653-3656
The acid catalysed cyclization of β-hydroxy selenide (), which was prepared from nerolidol () the epoxide (), was carried out to give bicyclic ether () directly which was further transformed into caparrapl oxide (). 相似文献
89.
Burrell KH Ejima S Schissel DP Brooks NH Callis RW Carlstrom TN Colleraine AP DeBoo JC Fukumoto H Groebner RJ Hill DN Hong R Hosogane N Jackson GL Jahns GL Janeschitz G Kellman AG Kim J Lao LL Lee P Lohr JM Luxon JL Mahdavi MA Moeller CP Ohyabu N Osborne TH Overskei D Petersen PI Petrie TW Phillips JC Prater R Scoville JT Seraydarian RP Shimada M Sleaford BW Snider RT Stambaugh RD Stav RD St John HE Stockdale R Strait EJ Taylor T Tooker JF Yamaguchi S 《Physical review letters》1987,59(13):1432-1435
90.
Sekiguchi A Nishina A Kimura H Fukumoto RH Kanoh K Ishihara H Koketsu M 《Chemical & pharmaceutical bulletin》2005,53(11):1439-1442
We investigated the superoxide anion scavenging effects of thirteen 2-amino-1,3-selenazoles using a highly sensitive quantitative chemiluminescence method. At 166 microM, the 2-amino-1,3-selenazoles scavenged in the range of 14.3 to 96.7% of O2-. 2-Piperidino-1,3-selenazole and 4-phenyl-2-piperidino-1,3-selenazole exhibited the strongest superoxide anion-scavenging activity among the 2-amino-1,3-selenazoles. The 50% inhibitory concentrations (IC50) of 2-piperidino-1,3-selenazole and 4-phenyl-2-piperidino-1,3-selenazole were determined to be 4.03 microM and 92.6 microM, respectively. Thus, these compounds acted in vitro as effective O2- scavengers. 相似文献