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931.
In this work, oximes are converted to their corresponding carbonyl compounds in good yields using N‐bromo‐N‐phenyl‐para‐toluenesulfonamide, under microwave irradiation. The simple work‐up procedure minimizes loss of product. 相似文献
932.
Line Lucry Ferdinand Enoma Franois Estour Sabine Mnager Olivier Lafont Hassan Oulyadi 《Journal of heterocyclic chemistry》2002,39(4):663-670
A series of 46 3‐phenyloctahydropyrimido[1,2‐a]‐s–triazine derivatives were synthesized. This synthesis was performed via iminodimethylation of dialkylated 2‐aminopyrimidinedione synthons by substituted primary arylamines. In vitro pharmacological evaluation of these compounds is reported. One of them exhibited antifungal activity against Microsporum canis (10?65010?5 mol/L), and another showed affinity for serotoninergic 5‐HT1A and 5‐HT2b receptors (10?85010?7 mol/L). 相似文献
933.
Inas El Hassan Robert Lauricella Béatrice. Tuccio 《Central European Journal of Chemistry》2006,4(2):338-350
The syntheses of seven N-aryl-C,C-dialkoxycarbonylnitrones 1–7, six of which were original, were achieved from the appropriate aryl-nitroso compounds. These ketonitrones were found to
trap efficiently carbon-centred free radicals in aqueous media, yielding stable aminoxyl radicals whose EPR spectra lasted
several days. The two penta-deuterated compounds 6 and 7 were also found to be efficient at trapping methoxyl radical. Their various spin adducts showed simple three line signals,
very sensitive to the polarity of the environment. This study represents the very first use of linear ketonitrones as spin
traps. 相似文献
934.
Nabil M. Hassan Abdelgawad A. Fahmi Fouad F. Abd-El-Mageid Abdou O. Abdelhamid 《中国化学会会志》1996,43(6):493-496
Several new pyrazolo[5,I-c]triazine, selenadiazoline, thiadiazoline, selenadiazolo[3,2-a]quitiazolone, and arylazothiazole derivatives were synthesised by the reaction of hydrazonoyl halides with different reagents. The structure of new heterocycles were assigned on the basis of their elemental analysis, spectral data, and alternate synthesis whenever possible. 相似文献
935.
PVC calcium ion-selective electrodes based on either calcium bis-di(n-decyl)phosphate or calcium bis-di[4-(1,1,3,3-tetramethylbutyl)phenyl]phosphate with various solvent mediators (alone or in pairs) have been evaluated with particular respect to interference from Na(+), K(+), Mg(2+), Sr(2+), Ba(2+), Mn(2+), Cu(2+), Ni(2+) and Zn(2+) ions. PVC calcium ion-selective electrodes based on calcium bis-di[4-(n-octyl)phenyl]phosphate with varied amounts of decan-l-ol plus di-n-octyl phenylphosphonate showed a continuous gradation in selectivity coefficients on going from a high fraction of decan-l-ol to a high fraction of the second mediator. Thus, k(pot)(Ca,Mg) changed from 1.6 for an electrode based exclusively on decan-l-ol to 4.9 x 10(-4) for one based completely on di-n-octyl phenylphosphonate. The corresponding k(pot)(Ca,Na) values were 7.0 x 10(-2) and 1.1 x 10(-3). 相似文献
936.
937.
938.
The secondary dissociation constants of α-phthalic and phosphoric acids have been determined in 50% w/w methanol-water mixture from the e.m.f measurements of the cell of the type: Pt; H2(1 atm), M2A(m), MHA(m), MCl, AgCl; Ag at different temperatures (288.15–308.15 K) and at different ionic strengths. The thermodynamic values ΔG°, ΔH°, ΔS° for the respective equilibria are estimated. The possibility of using these acids as basis for some buffer solutions in 50% methanol – water mixture is discussed. 相似文献
939.
Marchalín S Cvopová K Kriz M Baran P Oulyadi H Daïch A 《The Journal of organic chemistry》2004,69(12):4227-4237
(R)- and (S)-alpha-phenylethylamine (alpha-PEA: 7) have been used separately to resolve successfully a racemate 2-formyl-1,4-DHP derivative 4. The process was based on the difference of the solubility of both Schiff bases (6) since one of them crystallized out from the solution. These imines obtained by condensation of (R)-alpha-PEA (7) or (S)-alpha-PEA (7) with aldehyde (rac-4) were separated and analyzed by X-ray diffraction, and their exposition to an hydrochloric hydrolysis conditions led to the enantiopure (4R)-4 or (4S)-4 in excellent yields. Separate condensation of other chiral (8 and 13) and racemic (18) amino thiols as auxiliary with rac-4, (4S)-4, or (4R)-4 is accompanied by an in situ crystallization-induced dynamic resolution, whereby one distereomer of thiazole template selectively precipitates and can be isolated by simple filtration in 76-82% yield with dr > 99. The thiazole species isolated from this process resulted from an amino aldehyde condensation followed by a spontaneous thiol-imine cycloaddition. Finally, the racemate (+/-)-(4R,2'R)-19 and the diastereomerically pure homologous (4S,2'R)-23 and (4R,2'S)-20 (obtained in good yields (79-82%) from 2-aminoethanethiol (18) and 2-formyl-1,4-DHP derivative rac-4, (4S)-4, or (4R)-4, respectively) were converted conveniently in a one-pot procedure into newly tricyclic thiolactams in the DHP series in racemic ((+/-)-(6R,9bR)-21, 72% yield)) and enantiopure ((6S,9bR)-24, 71% yield); (6R,9bS)-24, 70% yield) forms. 相似文献
940.
Two novel uranyl PVC matrix membrane sensors responsive to uranyl ion are described. The first sensor incorporates tris(2-ethylhexyl)phosphate (TEHP) as both electroactive material and plasticizer and sodium tetraphenylborate (NaTPB) as an ion discriminator. The sensor displays a rapid and linear response for UO22+ ions over the concentration range 1×10−1–2×10−5 mol l−1 UO22+ with a cationic slope of 25.0±0.2 mV decade−1. The working pH range is 2.8–3.6 and the life span is 4 weeks. The second sensor contains O-(1,2-dihydro-2-oxo-1-pyridyl)-N,N,N′,N′-bis(tetra-methylene)uronium hexafluorophosphate (TPTU) as a sensing material, sodium tetraphenylborate as an ion discriminator and dioctyl phenylphosphonate (DOPP) as a plasticizer. Linear and stable response for 1×10−1–5×10−5 mol l−1 UO22+ with near-Nernstian slope of 27.5±0.2 mV decade−1 are obtained. The working pH range is 2.5–3.5 and the life span of the sensor is 6 weeks. Interference from many inorganic cations is negligible for both sensors. However, interference caused by some ions (e.g. Th4+, Cu2+, Fe3+) is eliminated by a prior ion exchange or solvent extraction step. Direct potentiometric determination of as little as 5 μg ml−1 uranium in aqueous solutions shows an average recovery of 97.2±1.3%. Application for the determination of uranium at levels of 0.01–1 wt.% in naturally occurring and certified ores gives results with good correlation with data obtained by X-ray fluorescence. 相似文献