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91.
Jun-Ichi Matsumoto Teruyuki Miyamoto Akira Minamida Yoshiro Nishimura Hiroshi Egawa Haruki Nishimura 《Journal of heterocyclic chemistry》1984,21(3):673-679
Fluorination of the 2,6-disubstituted 3-aminopyridines 5 and 12 by the Balz-Schiemann reaction is described. 2,6-Dichloro-3-pyridinediazonium tetrafluoroborate ( 6 ) and 2-substituted 6-acetylamino-3-pyridinediazonium tetrafluoroborates 13 were heated with or without a solvent to give the corresponding fluorinated pyridines 7 and 14 , respectively, in good yields. 2-Substituted 6-acetylamino-3-fluoropyridines ( 14 ) were converted by a known method into a series of 7-substituted 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids 21 including enoxacin [1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridine-3-carboxylic acid [( 2 )], a new potential antibacterial agent. 相似文献
92.
Yoshiro Ito Hajime Ohtani Shouji Ueda Yasuki Nakashima Shin Tsuge 《Journal of polymer science. Part A, Polymer chemistry》1994,32(2):383-388
The determination of end groups in polystyrenes (PSts) polymerized anionically with n-butyllithium as the initiator was carried out by pyrolysis-gas chromatography (Py-GC). The relative proportions of the end groups decrease with increasing molecular weight (MW). Consequently, the peaks which reflect the structure of the end groups can be distinguished by comparing pyrograms of samples with different MW. By comparing the intensities of these peaks relative to total intensities of all the peaks in the pyrogram, the numberaverage molecular weight (Mn) of the polymer can be estimated. The observed Mn values of PSts estimated by this method are compared with those determined by size exclusion chromatography (SEC). By this method it was possible to make direct determination of Mn values of PSts with MWs between 1000 and ca. 1 million. Furthermore, the calibration curve produced by the relative intensity of one of the most characteristic peaks (2-phenyl-1-heptene; C4H9? CH2C (Ph) = CH2) for the end group to total intensity of all the peaks in the pyrogram, gave rapid and highly reproducible Mn values. © 1994 John Wiley & Sons, Inc. 相似文献
93.
n-type organic field-effect transistors with very high electron mobility based on thiazole oligomers with trifluoromethylphenyl groups 总被引:1,自引:0,他引:1
Ando S Murakami R Nishida J Tada H Inoue Y Tokito S Yamashita Y 《Journal of the American Chemical Society》2005,127(43):14996-14997
Novel thiazole oligomers and thiazole/thiophene co-oligomers with trifluoromethylphenyl groups were developed as n-type semiconductors for OFETs. They showed excellent n-type performances with high electron mobilities. A 5,5'-bithiazole with trifluoromethylphenyl groups forms a closely packed two-dimensional columnar structure leading to a high performance n-type FET. The electron mobility was enhanced to 1.83 cm2/Vs on the OTS-treated substrate. 相似文献
94.
Queueing Systems - This paper proposes a new algorithm for computing the stationary distribution vector in continuous-time upper block-Hessenberg Markov chains. To this end, we consider the... 相似文献
95.
Intermolecular anionic rearrangement of the trimethylgermyl group in trimethylgermylacetonitrile, bis(trimethylgermyl)acetonitrile, and tris(trimethylgermyl)acetonitrile is described. 相似文献
96.
Yoshiro Ikeda 《Mathematische Zeitschrift》1925,22(1):16-25
Ohne Zusammenfassung 相似文献
97.
98.
Synthetic study for two 2H‐chromenic acids, 8‐chlorocannabiorcichromenic acid and mycochromenic acid
Seiji Yamaguchi Masahiro Nedachi Mikiko Maekawa Yohei Murayama Masahiro Miyazawa Yoshiro Hirai 《Journal of heterocyclic chemistry》2006,43(1):29-41
99.
Hydrogen peroxide in the presence of (NH4)6Mo7O24 · 4H2O and potassium carbonate is a chemoselective method to oxidize secondary alcohols to ketones and to oxidize aldehydes to acids, the latter also accelerated by cerium chloride. 相似文献
100.
Yamaguchi S Muro S Kobayashi M Miyazawa M Hirai Y 《The Journal of organic chemistry》2003,68(16):6274-6278
The absolute structures of some naturally occurring chiral 2-isopropenyl-2,3-dihydrobenzofurans, (+)-remirol (1a), (+)-remiridiol (1b), (+)-angenomalin (2), and (+)-isoangenomalin (3), were studied by respective chiral synthesis. Kinetic resolutions of racemic 2-isopropenyl-2,3-dihydrobenzofurans, 2-isopropenyl-4,6-dimethoxy-2,3-dihydrobenzofuran (4), 4-hydroxy-2-isopropenyl-2,3-dihydrobenzofuran-5-carbaldehyde (8), and 2-isopropenyl-6-(MOM)oxy-2,3-dihydrobenzofuran-5-carbaldehyde (11c), by Sharpless dihydroxylation using (DHQ)(2)AQN or (DHQD)(2)AQN gave the corresponding chiral 2-isopropenyl-2,3-dihydrobenzofurans. Chiral (S)-(+)-4 (99% ee, using (DHQD)(2)AQN) was converted to natural remirol (S)-(+)-1a and then to natural remiridiol (S)-(+)-1b. (S)-(+)-8 (97% ee, using (DHQD)(2)AQN) was converted to natural angenomalin (S)-(+)-2. (R)-(-)-11c (>99% ee, using (DHQ)(2)AQN), was converted to natural isoangenomalin (R)-(+)-3. Thus, the absolute structures of natural remirol (+)-1a and remiridiol (+)-1b and angenomalin (+)-2 were determined to be S, and the structure of natural isoangenomalin (+)-3 was R. 相似文献