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931.
932.
Kenji Yamagishi Keiko Yamamoto Sachiko Yamada Hiroaki Tokiwa 《Chemical physics letters》2006,420(4-6):465-468
Fragment molecular orbital–interfragment interaction energy calculations of the vitamin D receptor (VDR)/1,25-dihydroxyvitamin D3 complex were utilized to assign functions of key residues of the VDR. Only one residue forms a significant interaction with the corresponding hydroxy group of the ligand, although two residues are located around each hydroxy group. The degradation of binding affinity for derivatives upon removal of a hydroxy group is closely related to the trend in the strength of the hydrogen bonds. Type II hereditary rickets due to an Arg274 point mutation is caused by the lack of the strongest hydrogen bond. 相似文献
933.
[formula: see text] The first total synthesis of spicamycin amino nucleoside 2 has been achieved. The aminoheptose unit 5 was prepared stereoselectively from myo-inositol, and the characteristic N-glycoside linkage was constructed by way of Pd-catalyzed coupling reaction of 5 with 6-chloropurine derivative 6. 相似文献
934.
Alkynyl ketones can be reduced to chiral propargylic alcohols by a complex aluminum hydride modified by chiral 2,2′-dihydroxy-1,1′-binaphthyl. The synthetic utility has been demonstrated by the synthesis of the Japanese beetle and rove beetle pheromones. 相似文献
935.
Uneven dielectric barrier discharge (DBD) reactors driven by positive–negative pulse plasma discharges were investigated for particulate matter (PM) removal from a diesel engine. Two kinds of uneven alumina plates and three kinds of uneven stainless steel plates were used to assemble six kinds of uneven DBD reactors of discharge gaps 0.4–1.0 mm. The experimental results show that PM from diesel engines can be removed using the uneven DBD reactors. The maximum PM removal was 67% at 300 W energy injections using the DBD reactor of 0.4 mm gap distance. PM removal increased with decreasing gap distance. The energy efficiency using the uneven DBD reactor of a shorter gap distance was higher than that using the uneven DBD reactor of a longer gap distance as the uneven DBD reactor of a shorter gap distance has a higher PM deposition rate. The energy efficiency was typically in a range of 3–10.6 g/kWh at an energy density of 2–16 J/L. A comparison of this study with reports given by other research groups is given. 相似文献
936.
H Saji Y Magata Y Yamada K Tajima Y Yonekura J Konishi Y Ohmomo A Yokoyama 《Chemical & pharmaceutical bulletin》1992,40(3):734-736
A nicotine agonist, 11C-labeled (S)-nicotine, was synthesized by N-methylation of (S)-nornicotine with [11C]-methyl iodide in dimethylformamide-dimethylsulfoxide in order to study nicotinic receptors in the human brain by positron emission tomography. The radiochemical yield of this N-methylation reaction was more than 90% within 5 min. After purification by high performance liquid chromatography the radiochemical purity of the product was more than 99% and the specific radioactivity was 7.4-11.1 GBq/mumol. The regional distribution of (S)-[11C]nicotine in the mouse brain after intravenous injection was compared with that of (R)-[11C]nicotine. After injection of (S)-[11C]nicotine, the regional uptake of radioactivity was in the following order: cortex greater than thalamu approximately hippocampus greater than striatum greater than hypothalamus greater than cerebellum. Moreover, (S)-[11C]nicotine was displaced from the brain by unlabeled (S)-nicotine, but unlabeled (R)-nicotine caused no change in uptake. In contrast, (R)-[11C]nicotine showed a lower brain uptake and lesser regional differences in radioactivity. 相似文献
937.
Ichikawa T Kitazaki T Matsushita Y Hosono H Yamada M Mizuno M Itoh K 《Chemical & pharmaceutical bulletin》2000,48(12):1947-1953
New routes for the synthesis of the optically active antifungal triazoles 1-[(1R,2R)-2-(2,4-difluorophenyl)-2-hydroxy-1-methyl-3-(1H-1,2,4-triazol-1-yl)propyl]-3-[4-(1H-1-tetrazolyl)phenyl]-2-imidazolidinone (1b) and the 3-14-(1H-1,2,3-triazol-1-yl)phenyl]-2-imidazolidinone analog (1a) that possess an imidazolidine nucleus were established. The key synthetic intermediates, (2R,3R)-3-(2,2-diethoxvethyl)amino-2-(2,4-difluorophenyl)-1-(1H1,2,4-triazol-1-yl)-2-butanol (8) and (2R,3R)-2-(2,4-difiuorophenyl)-3-(2-h ydroxyethyl)amino-1-(1H-1,2,4-triazol-1-yl)-2-butanol (14), were prepared by the ring-opening reaction of the oxirane (2) with the corresponding 2-substituted ethylamines. The acetal (8) was converted to the imidazolidinones (1a, b) by condensation with the carbamates (10a, b) followed by treatment with hydrochloric acid and subsequent catalytic hydrogenation. The candidate selected for the clinical trials, 1b (TAK-456), was alternatively prepared from the hydroxyethylamino intermediate (14) via two reaction steps: condensation with the carbamate (10b) to the urea (15) and subsequent cyclization to the imidazolidinones. This newly developed synthetic route could be applied to a large scale preparation of 1b. 相似文献
938.
Sato J Saito N Yamada Y Maeda K Takata T Kondo JN Hara M Kobayashi H Domen K Inoue Y 《Journal of the American Chemical Society》2005,127(12):4150-4151
Germanium nitride beta-Ge3N4 dispersed with RuO2 nanoparticles is presented as the first example of a non-oxide photocatalyst for the stoichiometric decomposition of H2O into H2 and O2. All of the successful photocatalysts developed for overall water splitting over the past 30 years have been based on oxides of metals. The discovery of a non-oxide photocatalyst, such as nitrides and oxynitrides, achieving the same function is therefore expected to stimulate research on non-oxide photocatalysts. New opportunities for progress in the development of visible light-driven photocatalysis can thus be expected, as the higher valence band positions of metal nitrides compared to the corresponding metal oxides provide narrower band gaps, which are suitable for visible light activity. 相似文献
939.
Masao Kaneko Masahisa Ochiai Kazuhiko Kinosita Akira Yamada 《Journal of polymer science. Part A, Polymer chemistry》1982,20(4):1011-1019
The characteristics of the photoinduced electron transfer reaction from polystyrene pendant tris(2,2′-bipyridyl)ruthenium (II) complex [Ru(bpy)] to methylviologen (MV2+) were studied. The rate constant k1 from the excited state of the complex, Ru(bpy), to MV2+ were determined for both the polymeric and monomeric complexes from the lifetime τ of Ru(bpy) and the quenching rate of Ru(bpy) by MV2+. The polymer pendant Ru(bpy) showed three kinds of τ components ranging from 7 to 474 ns, in contrast to the monomeric complex, which showed one component of 350 ns. The k1 values for both complexes were almost the same, on the order of 108 L/mol s. The photoinduced electron transfer from solid-phase Ru(bpy) to liquid-phase MV2+ was realized by utilizing the polymer complex, and the solid–liquid interphase reaction system is discussed. 相似文献
940.