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41.
Moridi N Danylyuk O Suwinska K Shahgaldian P 《Journal of colloid and interface science》2012,377(1):450-455
The title compound, 5,11,17,23-tetra-carboxy-25,26,27,28-tetradodecyloxy-calix[4]arene, 1, has been studied at the air–water interface, self-assembled as Langmuir monolayers, for its ability to interact with an active pharmaceutical ingredient (API), acetaminophen (APAP), and to initiate its crystallization. The Π/A isotherm study shows that there is a clear interaction between 1 and APAP causing an expansion of the monolayer. In addition to the known phase transition occurring at a surface tension of 38 mN m?1, an additional kink is observed in the compression isotherm for concentrations of APAP above 40 mM suggesting that this API is causing an additional phase transition of the monolayer. Interface-initiated crystallization studies show that the presence of a monolayer spread on a supersaturated solution of APAP (26 g L?1) triggers this API crystal growth from the interface. The transfer of 1-based monolayers on glass surfaces has been carried out using the Langmuir–Blodgett technique. The so-produced monolayers have been shown to template the crystallization of APAP. LB films of 1 have characterized using imaging and spectroscopic ellipsometry. The results suggest that each monolayer has an average thickness of 18 Å, which is consistent with the molecular structure of 1 self-organized parallel to the interface with the alkyl chains pointing out parallel to the axis of the macrocycle and without interdigitation of the alkyl chains. The presence of APAP in the subphase during the LB transfer causes a limited but relevant increase in the layer thickness. The study of the capabilities of the LB films to initiate crystallization of APAP is also demonstrated showing the influence of the monolayer packing on the quantity of formed crystals. 相似文献
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Krystian Pluta Kinga Suwiska 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(3):374-375
The title compound, C19H13N3S, is folded, with the central ring in a boat conformation. The folding angle between the two quinoline rings is 150.2 (1)°. The 14‐methyl substituent is in a quasi‐axial orientation with respect to the thiazine ring. The S?N—Cmethyl angle is 120.1 (1)°. 相似文献
45.
Kinga Suwiska Boenna Golankiewicz Wojciech Zielenkiewicz 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(6):767-769
The biologically important molecule tricyclic acyclovir, presented here as 3‐[(2‐hydroxyethoxy)methyl]‐6‐methyl‐3H‐imidazolo[1,2‐a]purin‐9(5H)‐one dihydrate, C11H13N5O3·2H2O, shows conformational flexibility, which is observed in the solid state as two symmetrically independent molecules with different side‐chain conformations. Additionally, one of these molecules exhibits side‐chain disorder, such that there are three different conformations in the crystal. Water molecules found in the crystal form (H2O)8 clusters which are located between molecules of tricyclic acyclovir. The complex hydrogen‐bond network formed between water and tricyclic acyclovir in the solid state may be related to the solvation of the molecules in solution. 相似文献
46.
Karolina Syrek Monika Sotys-Mrz Kinga Pawlik Magdalena Gurgul Grzegorz D. Sulka 《Molecules (Basel, Switzerland)》2022,27(15)
In this work, we present a systematic study on the influence of Cu2+ ion concentration in the impregnation solution on the morphology, structure, optical, semiconducting, and photoelectrochemical properties of anodic CuOx-TiO2 materials. Studied materials were prepared by immersion in solutions with different concentrations of (CH3COO)2Cu and subjected to air-annealing at 400 °C, 500 °C, or 600 °C for 2 h. The complex characterization of all studied samples was performed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), reflectance measurements, Mott–Schottky analyses, and photocurrent measurements. It was found that band gap engineering based on coupling CuO with TiO2 (Eg~3.3 eV) is an effective strategy to increase the absorption in visible light due to band gap narrowing (CuOx-TiO2 materials had Eg~2.4 eV). Although the photoactivity of CuO-TiO2 materials decreased in the UV range due to the deposition of CuO on the TiO2 surface, in the Vis range increased up to 600 nm at the same time. 相似文献
47.
Zbigniew Ka?u?a Arkadiusz KazimierskiKrzysztof Lewandowski Kinga SuwińskaBeata Szcz?sna Marek Chmielewski 《Tetrahedron》2003,59(31):5893-5903
Starting from (l)-ethyl lactate and 4-vinyloxy-azetidin-2-one the diastereomeric (4S,6R)- and (4S,6S)-4-methyl-5-oxa-3-methylene and 3-oxo-cephams were obtained. The formation of the cepham skeleton proceeds with a diastereomeric excess up to 80%, depending on catalyst and reaction conditions. For comparison, the corresponding racemic cephams lacking a methyl at C-4 or with a gem-dimethyl group at C-4 were synthesized. 相似文献
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A new method was developed to analyze the stable carbon and oxygen isotope ratios of small samples (400 +/- 20 micro g) of calcium carbonate. This new method streamlines the classical phosphoric acid/calcium carbonate (H(3)PO(4)/CaCO(3)) reaction method by making use of a recently available Thermoquest-Finnigan GasBench II preparation device and a Delta Plus XL continuous flow isotope ratio mass spectrometer. Conditions for which the H(3)PO(4)/CaCO(3) reaction produced reproducible and accurate results with minimal error had to be determined. When the acid/carbonate reaction temperature was kept at 26 degrees C and the reaction time was between 24 and 54 h, the precision of the carbon and oxygen isotope ratios for pooled samples from three reference standard materials was =0.1 and =0.2 per mill or per thousand, respectively, although later analysis showed that materials from one specific standard required reaction time between 34 and 54 h for delta(18)O to achieve this level of precision. Aliquot screening methods were shown to further minimize the total error. The accuracy and precision of the new method were analyzed and confirmed by statistical analysis. The utility of the method was verified by analyzing calcite from Devils Hole, Nevada, for which isotope-ratio values had previously been obtained by the classical method. Devils Hole core DH-11 recently had been re-cut and re-sampled, and isotope-ratio values were obtained using the new method. The results were comparable with those obtained by the classical method with correlation = +0.96 for both isotope ratios. The consistency of the isotopic results is such that an alignment offset could be identified in the re-sampled core material, and two cutting errors that occurred during re-sampling then were confirmed independently. This result indicates that the new method is a viable alternative to the classical reaction method. In particular, the new method requires less sample material permitting finer resolution and allows automation of some processes resulting in considerable time savings. 相似文献
50.
Godsi O Turner B Suwinska K Peskin U Eichen Y 《Journal of the American Chemical Society》2004,126(41):13519-13525
The enolpyridine, OH-ketoenamime, NH equilibrium in crystals of 1,3-bis(pyridin-2-yl)propan-2-one was studied using temperature-dependent single-crystal X-ray diffraction. The relative population of the different tautomers was found to be sensitive to the temperature in the range of 100-300 K, illustrating the small thermodynamic difference between these two tautomers. This energy resemblance is partially attributed to the molecular packing in the crystal, where the molecules are arranged in the form of dimers. Ab initio electronic energy calculations (HF/6-31G** and MP2/6-31G**) reveal the effect of dimerization in the crystal on the electronic energy levels. Several tautomeric states were identified in the dimer of 1,3-bis(pyridin-2-yl)propan-2-one. A model is proposed in which four of these dimer states are populated in the crystal at ambient temperatures. The crystallographic data were treated according to this four-state dimer model, suggesting that the free energy of the OH-NH dimers is higher than that of the OH-OH dimers by 120 +/- 10 cal mol(-1) and that the NH-NH dimers are yet higher in free energy by 50 +/- 10 cal mol(-1). 相似文献