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51.
Găină L Csámpai A Túrós G Lovász T Zsoldos-Mády V Silberg IA Sohár P 《Organic & biomolecular chemistry》2006,4(23):4375-4386
A series of novel 3(5)-aryl/ferrocenyl-5(3)-phenothiazinylpyrazoles and pyrazolines were obtained by substituent-dependent regioselective condensation of the corresponding (E)-3-(2-alkyl-10H-phenothiazin-3-yl)-1-aryl/ferrocenylprop-2-en-1-one with hydrazine or methylhydrazine in acetic acid. The different propensity of the primary formed beta-hydrazino adducts to undergo competitive retro-Mannich reaction was interpreted in terms of tautomerisation equilibrium constants calculated by DFT using a solvent model. The regioselectivity of the cyclisation reactions with methylhydrazine and the substituent-dependent redox properties of pyrazolines were also rationalized by comparative DFT calculations performed for simplified model molecules. On the effect of ultrasound-promoted oxidation with copper(II)nitrate phenothiazine-containing pyrazolines, enones and oxo-compounds were selectively transformed into sulfoxides. Only one sulfoxide enone was partially converted into an oxirane derivative. The structure of the novel products was determined by IR and NMR spectroscopy including COSY, HSQC, HMBC and DNOE measurements. 相似文献
52.
Application of a cinchona alkaloid-based chiral anion-exchanger stationary phase for the direct high-performance liquid chromatographic enantioseparation of N-protected unusual phenylalanine analogs is reported. The N-benzyloxycarbonyl, N-3,5-dinitrobenzyloxycarbonyl, N-benzoyl and N-3,5-dinitrobenzoyl derivatives were well separable with high resolution. To achieve optimal separation of the enantiomers, the chromatographic conditions and temperature were varied. Linear van't Hoff plots were observed in the studied temperature range, 278-343 K, and the apparent changes in enthalpy, delta(deltaH degrees), entropy, delta(delta S degrees), and Gibbs free energy, delta(delta G degrees), were calculated. The values of the thermodynamic parameters depended on the nature of the N-acyl groups, on the structures of the compounds, and especially on the nature of the substituent on C3 of phenylalanine. 相似文献
53.
Ya. R. Bazel I. P. Antal V. M. Lavra Zh. A. Kormosh 《Journal of Analytical Chemistry》2014,69(3):211-236
Methods for the determination of synthetic anionic surfactants published in the past two decades are considered, and their advantages and disadvantages are demonstrated. Spectrophotometric and potentiometric (with the use of ion-selective electrodes) techniques, including flow injection analysis versions, are used for the determination of anionic surfactants. Chromatographic techniques (primarily, high-performance liquid chromatography) are most frequently used for the separation, preconcentration, and determination of anionic surfactants in complex mixtures. Spectrofluorimetry, voltammetry, and immunoassay did not find wide application. 相似文献
54.
We study the Abelian sandpile model on . In d ≥ 3 we prove existence of the infinite volume addition operator, almost surely with respect to the infinite volume limit μ of the uniform measures on recurrent configurations. We prove the existence of a Markov process with stationary measure μ, and study ergodic properties of this process. The main techniques we use are a connection between the statistics of waves
and uniform two-component spanning trees and results on the uniform spanning forest measure on .
相似文献
55.
Dávid Ádám Zoltán Mincsovics Emil Pápai Katalin Ludányi Krisztina Antal István Klebovich Imre 《平面色谱法杂志一现代薄层色谱法》2008,21(2):119-123
JPC – Journal of Planar Chromatography – Modern TLC - A new, simplified open-vessel microwave extraction (OVME) method has been used to prepare aqueous extracts of Sennae folium and... 相似文献
56.
Mincsovics Emil Pápai Katalin Ludányi Krisztina Dávid Ádám Zoltán Budai Marianna Antal István Klebovich Imre 《平面色谱法杂志一现代薄层色谱法》2008,21(5):361-366
JPC – Journal of Planar Chromatography – Modern TLC - The newly developed experimental OPLC separation unit 100 (OSU 100) has been used for fully on-line multiple hyphenation using the... 相似文献
57.
Rockenbauer A Clément JL Culcasi M Mercier A Tordo P Pietri S 《The journal of physical chemistry. A》2007,111(23):4950-4957
Experiments were performed to elucidate the origin of the superhyperfine structure and line width alternation (LWA) seen in the ESR spectrum of the major diastereoisomer (1) of DEPMPO-OOH, the remarkably persistent superoxide adduct of 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline N-oxide (DEPMPO). Using selectively deuterated DEPMPO derivatives, we demonstrated that the superhyperfine pattern can be unambiguously attributed to long-range couplings. The recording in pyridine of highly resolved spectra in a wide temperature range, combined with two-dimensional simulation, allowed us to characterize an inverted LWA in 1 and revealed a uniform line broadening in the spectrum of the minor DEPMPO-OOH diastereoisomer (2), with both effects originating from a chemical exchange between conformers. When the individual spectra of 1 presenting LWA in the fast-exchange regime were simulated, four equally good fits were obtained and this ambiguity could be resolved by using a two-dimensional simulation technique. The thermodynamic and kinetic constants of this exchange were consistent with a rotation around the O-O bond. We propose that line broadening effects in 1 and 2 result from this O-O rotation concerted with the pseudo-rotation of the pyrrolidine ring. 相似文献
58.
A highly efficient trifluoromethanesulfonic acid-mediated rearrangement of the benzoylaminomethylthio group of 3-benzoylaminomethylthioindoles (7a-e) to position 2 of the indole ring was developed. Thus, 2-benzoylaminomethylthioindoles (9a-e) were obtained in good yields and were involved as key intermediates in the synthesis of the new γ-carboline analogue ring system: 2,9-dihydro-4-aryl-1,3-thiazino[6,5-b]indole derivatives (11a-e). The target thiazinoindoles (11a-e) were prepared via 2-thiobenzoylaminomethylindoles (10a-e) in modified Bischler-Napieralski reactions. 相似文献
59.
The retention of enantiomers of chiral analytes, i.e. alpha-substituted glycine analogs, on a quinine-based anion-exchanger chiral stationary phase was studied in the temperature range of 5-70 degrees C and at different mobile phase compositions, using isocratic elution in the reversed-phase mode. By variation of both mobile phase composition and temperature, baseline separations could be achieved for these enantiomers. Separation could be optimized more quickly by adjusting the column temperature rather than the mobile phase composition. The dependence of the natural logarithms of retention and selectivity factors (lnk' and lnalpha) on the inverse of temperature, 1/T (van't Hoff plots) was used to determine thermodynamic data on the enantiomers. Calculated thermodynamic constants (Delta(DeltaH degrees ), Delta(DeltaS degrees ) and Delta(DeltaG degrees )) were applied to promote an understanding of the thermodynamic driving forces for retention in this chromatographic system. The elution sequence of the enantiomers in most cases was determined. 相似文献
60.
Károlyi BI Bösze S Orbán E Sohár P Drahos L Gál E Csámpai A 《Molecules (Basel, Switzerland)》2012,17(3):2316-2329
A series of novel functionalized mono-, bis- and tris-(S)-{[(2S,4R,8R)-8-ethyl-quinuclidin-2-yl](6-methoxyquinolin-4-yl)}methanamines including ferrocene-containing derivatives was obtained by the reaction of the precursor amine with a variety of acylation agents. Their in vitro antitumor activity was investigated against human leukemia (HL-60), human neuroblastoma (SH-SY5Y), human hepatoma (HepG2) and human breast cancer (MCF-7) cells by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT)-assay and the 50% inhibitory concentration (IC(50)) values were determined. Our data indicate that the precursor amine has no antitumor activity in vitro, but the bis-methanamines with ureido-, thioureido and amide-type linkers display attractive in vitro cytotoxicity and cytostatic effects on HL-60, HepG2, MCF-7 and SH-SY5Y cells. Besides 1H- and 13C-NMR methods the structures of the new model compounds were also studied by DFT calculations. 相似文献