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991.
Dr. Eiichi Kayahara Kei Fukayama Prof. Tohru Nishinaga Prof. Dr. Shigeru Yamago 《化学:亚洲杂志》2016,11(12):1793-1797
The oxidation processes of [n]cycloparaphenylenes ([n]CPPs) (n=5–12) were systematically investigated by cyclic and rotating disk electrode voltammetry. All CPPs underwent pseudo‐reversible two‐electron oxidation irrespective of ring size, forming the corresponding radical cations and then dications. The results were in sharp contrast to those observed for linear oligoparaphenylenes, which only undergo one‐electron oxidation. The difference in the first and second oxidation potentials in the CPP oxidation was affected by the ring size and became more significant as the decrease of CPP size. In other words, while the first oxidation from neutral CPP to the radical cation occurred faster as the size of CPP becomes smaller, the second oxidation from the radical cation to dication exhibited opposite size dependence. 相似文献
992.
Shigeo Yoneda Kenji Ozaki Akira Tsubouchi Hideo Kojima Kazunori Yanagi 《Journal of heterocyclic chemistry》1988,25(2):559-563
The synthesis of tetrakis(alkylthio)thieno[3,4-c]thiophenes la-e by the dimerization reaction of bis(alkylthio)cyclopropenethiones is described. The remarkable thermodynamic and kinetic stability suggests the significant electron-accepting conjugation of the alkylthio substituents to the carbanionic 1, 3, 4, and 6 carbons in the framework. The isopropylthio- and ethylthio-substituted thienothiophenes 1d and 1e undergo cycloaddition reactions with dienophiles such as N-phenylmaleimide and dimethyl acetylenedicarboxylate to give the cycloadducts in moderate yields. 相似文献
993.
Shinji Ando Tohru Matsuura Shigekuni Sasaki 《Journal of polymer science. Part A, Polymer chemistry》1992,30(11):2285-2293
We measured the 15N-, 1H-, and 13C-NMR chemical shifts for a series of aromatic diamines and aromatic tetracarboxylic dianhydrides dissolved in DMSO-d6, and discuss the relationships between these chemical shifts and the rate constants of acylation (k) as well as such electronic-property-related parameters such as ionization potential (IP), electronic affinity (EA), and the energy ε of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). The 15N chemical shifts of the amino group of diamines (δN) depend monotonically on the logarithm of k (log k) and on IP. We inferred the reactivities of diamines whose acylation rates have not been measured from their δN, and we propose an arrangement of diamines in the order of their reactivity. The 1H chemical shift of amino hydrogens (δH) and the 13C chemical shift of carbons bonded to nitrogen (δC) are roughly proportional to δN, but these shifts are not as closely correlated with log k and IP. Although the 13C chemical shifts of the carbonyl carbon of dianhydrides (δC,) varies much less than the δC and δN of diamines, δC, can be an index of acylation reactivity for dianhydrides because it is closely correlated with εLUMO. These facts indicate that the chemical shifts of diamines and dianhydrides are displaced according to their electron-donor and electron-acceptor properties, and that these chemical shifts can be used as indices of the electronic properties of monomers. Changes in reactivity caused by the introduction of trifluoromethyl groups into diamines and dianhydrides are inferred from the displacements of δN and δC © 1992 John Wiley & Sons, Inc. 相似文献
994.
CF3Br? H2 mixtures highly diluted with Ar were studied by using a time-resolved IR-emission of HBr and a gas-chromatography for reaction products. The temperature range covered was 1000–1600 K and the total pressure behind the reflected shock waves used was 1.2–2.6 atm. CF3H, C2F6, and C2F4 were produced and the yields of these products were determined as a function of temperature. The main product under our experimental conditions was CF3H. The mechanism and the rate constants of CF3Br? H2 reaction at high temperatures were discussed. The experimental data was satisfactorily modeled using a 14-reaction mechanism. Reaction (5) played an important role in the formation of CF3H together with reaction (4). The rate constant expression k5 = 2.2 × 1013 exp(?12 kcal/RT) cm3 mol?1 s?1 gave the best agreement between the calculated and observed results. © 1993 John Wiley & Sons, Inc. 相似文献
995.
996.
Jun Segawa Masahiko Kitano Kenji Kazuno Masami Tsuda Ichiro Shirahase Masakuni Ozaki Masato Matsuda Masahiro Kise 《Journal of heterocyclic chemistry》1992,29(5):1117-1123
A series of 8-substituted-7-fluoro-5-oxo-5H-thiazolo[3,2-a]quinoline-4-carboxylic acids was prepared and evaluated for antibacterial activity. These compounds were synthesized from ethyl 2-mercaptoquinoline-3-carboxylates 17 which were obtained from anilines 11 by a route involving an intramolecular cyclization reaction. 相似文献
997.
Huang H Hu Y Zhang J Sato H Zhang H Noda I Ozaki Y 《The journal of physical chemistry. B》2005,109(41):19175-19183
Miscibility and hydrogen-bonding interactions, as well as the morphological properties, of biodegradable polymer blends of poly(3-hydroxybutyrate) (PHB) and a 80% hydrolyzed poly(vinyl alcohol) (PVA80) were studied using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). It was found that PHB is miscible with PVA80 in the amorphous phase over the whole composition range. PVA80 or PHB assumes the amorphous state when its content in the blend is lower than 30 or 20 wt %, respectively. Due to the heavy overlapping of C=O stretching bands from both PVA80 and PHB and the nonmeasurable peak shift in the OH stretching band region, hydrogen-bonding interactions between the OH group of PVA80 and the C=O group of PHB were not detectable at room temperature, but were observed at a higher temperature of 180 degrees C. This is because hydrogen-bonding interactions are promoted above the melting points of these two crystalline polymers, by increasing the mixing entropy and reducing the Deltachi effect. Blending PHB with PVA80 does not have a significant effect on the OH groups of PVA80 that are hydrogen bonded with each other. Instead, the C=O groups of PHB dispossess some of the OH groups that are hydrogen bonded to the C=O groups of PVA80, which gives rise to the miscibility between PVA80 and PHB in the amorphous phase. 相似文献
998.
The Pictet-Spengle P-S reaction of Nb-hydroxytryptamines 5 and cysteinals 6 in the presence of trifluoroacetic acid(TFA) at room, temperature gave the tetracyclic compounds 7 as well as the corresponding Nb-hydroxy-β-carbolines 8. The optically active nitrones 9, isolated from the similar reaction of 5 and optically active 6, gave optically active 7 and 8. 相似文献
999.
[reaction: see text] The enantioselective borodeuteride reduction catalyzed by optically active beta-ketoiminato cobalt complexes was applied to N-(di(o-tolyl)phosphinyl)aldimines to afford the corresponding optically active deuterated primary amines in high yields with high enantiomeric excesses after simple deprotection. The present deuteride reduction of aldimines is in the opposite sense of the enantioselective for the previously reported borohydride reduction of ketones or diphenylphosphinyl aldimines. The stereochemical course in these enantioselective reductions is discussed. 相似文献
1000.
Correlation of liquid-liquid equilibria in aqueous and organic systems using a modified Wilson model
A modified Wilson model is extended to involve three ternary parameters per ternary to allow the model to represent ternary liquid-liquid equilibria accurately. The calculated results for 19 ternary systems obtained from the present modification are compared with the previous results obtained from other modified Wilson models. The model is further extended to treat quaternary liquid-liquid equilibria for six aqueous systems and one nonaqueous system using binary, ternary, and quaternary parameters. Mutual solubilities for 19 systems over a wide temperature range are represented with the model having temperature-dependent energy parameters. 相似文献