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71.
M. Bonelli A.C. Ferrari A. Fioravanti A. Li Bassi A. Miotello P.M. Ossi 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,25(3):269-280
Tetrahedral amorphous carbon films have been produced by pulsed laser deposition, at a wavelength of 248 nm, ablating highly
oriented pyrolytic graphite at room temperature, in a 10-2 Pa vacuum, at fluences ranging between 0.5 and 35 Jcm-2. Both (100) Si wafers and wafers covered with a SiC polycrystalline interlayer were used as substrates. Film structure was
investigated by Raman spectroscopy at different excitation wavelength from 633 nm to 229 nm and by transmission Electron Energy
Loss Spectroscopy. The films, which are hydrogen-free, as shown by Fourier Transform Infrared Spectroscopy, undergo a transition
from mainly disordered graphitic to up to 80% tetrahedral amorphous carbon (ta-C) above a threshold laser fluence of 5 J cm-2. By X-ray reflectivity roughness, density and cross-sectional layering of selected samples were studied. Film hardness as
high as 70 GPa was obtained by nanoindentation on films deposited with the SiC interlayer. By scratch test film adhesion and
friction coefficients between 0.06 and 0.11 were measured. By profilometry we obtained residual stress values not higher than
2 GPa in as-deposited 80% sp3 ta-C films.
Received 25 June 2001 相似文献
72.
Maria Quant Dr. Anders Lennartson Ambra Dreos Mikael Kuisma Paul Erhart Karl Börjesson Dr. Kasper Moth‐Poulsen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13265-13274
Molecular solar‐thermal energy storage systems are based on molecular switches that reversibly convert solar energy into chemical energy. Herein, we report the synthesis, characterization, and computational evaluation of a series of low molecular weight (193–260 g mol?1) norbornadiene–quadricyclane systems. The molecules feature cyano acceptor and ethynyl‐substituted aromatic donor groups, leading to a good match with solar irradiation, quantitative photo‐thermal conversion between the norbornadiene and quadricyclane, as well as high energy storage densities (396–629 kJ kg?1). The spectroscopic properties and energy storage capability have been further evaluated through density functional theory calculations, which indicate that the ethynyl moiety plays a critical role in obtaining the high oscillator strengths seen for these molecules. 相似文献
73.
Fioravanti S Colantoni D Pellacani L Tardella PA 《The Journal of organic chemistry》2005,70(8):3296-3298
Aza-MIRC (Michael-initiated ring closure) and C-H insertion products were obtained in the reactions of trifluoromethylated olefins with different nosyloxycarbamates by changing base and solvent. Aza-Michael addition products were not isolated. The presence and the position of the trifluoromethyl group allow control of the outcome of the reactions. 相似文献
74.
Cecchet F Fioravanti G Marcaccio M Margotti M Mattiello L Paolucci F Rapino S Rudolf P 《The journal of physical chemistry. B》2005,109(39):18427-18432
Ordered thin layers of a spirobifluorene derivative containing an amino group were formed by grafting them onto a self-assembled monolayer (SAM) of 11-mercaptoundecanoic acid (11-MUA) on gold. Either physical (H-bonding) or chemical bonding (activated by EDCl) was investigated. X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy confirmed that both methods can be used to effectively graft 2-amino-9,9'-spirobifluorene molecules onto the SAM surface, giving high surface coverages, with a significantly higher packing in the case of chemisorbed films. EIS measurements also showed that the covalently bonded spirobifluorene SAMs act as an effective barrier to both ion penetration and heterogeneous electron transfer. 相似文献
75.
Enantioselective aza-Michael initiated ring closure (MIRC) additions of ethyl nosyloxycarbamate to 2-(phenylsulfanyl)-2-cycloalkenones catalysed by Cinchona alkaloids were studied. The results suggest that the enantioselectivity obtained is influenced by the structure of the catalyst and the different amination conditions. Substrate ring size also plays an important role. 相似文献
76.
D.M. DAmbra J.V. Marzik R. Kershaw J. Baglio K. Dwight A. Wold 《Journal of solid state chemistry》1985,57(3):351-356
Single crystals of MoS2 and WS2 were grown by chemical vapor transport in both the presence and absence of cobalt. Hall measurements indicate that cobalt cannot diffuse appreciably into the bulk of MoS2 or WS2 and, therefore, can be present only on the surface. Similar results were obtained for as-grown crystals annealed or sulfided in contact with Co9S8 or sulfided after being dipped in a 0.1M CoSO4/methanol solution. 相似文献
77.
Laura CarrocciaStefania Fioravanti Lucio Pellacani Claudia SadunPaolo A. Tardella 《Tetrahedron》2011,67(30):5375-5381
(E)-Trifluoromethyl imines were considered as ideal substrates to be transformed into the corresponding diaziridines by a direct amination reaction with nosyloxycarbamates. The diastereoselective induction was strongly controlled by the N-substituent. Similar results were obtained in the epoxidation reactions performed on the same substrates using m-CPBA as oxidant. Starting from enantiopure imines chiral diaziridines or oxaziridines were obtained with very high enantiopurity. 相似文献
78.
We study the form of the high spin expansion of the minimal anomalous dimension for long operators belonging to the sl(2) sector of SYM. Keeping fixed the ratio j between the twist and the logarithm of the spin, the minimal anomalous dimension expands as γ(g,j,s)=f(g,j)lns+f(0)(g,j)+O(1/lns). This particular double scaling limit is efficiently described, including the desired accuracy O((lns)0), in terms of a linear integral equation. By its use, we are able to evaluate both at weak and strong coupling the subleading scaling function f(0)(g,j) as a series in j, up to the order j5. Thanks to these results, the possible extension of the liaison with the O(6) non-linear sigma model may be tackled on a solid ground. 相似文献
79.
Stefania Fioravanti M. Antonietta Loreto Lucio Pellacani Paolo A. Tardella 《Tetrahedron: Asymmetry》1990,1(12):913-930
Thermal reaction of ethyl azidoformate with proline-derived optically active enamines of cyclohexanone, followed by photolysis, proceeds with opposite facial selectivity to that observed using (ethoxycarbonyl)nitrene. A tentative explanation is proposed. The absolute configuration of the main product, 2-(ethoxycarbonylamino)cyclohexanone (6), was deduced by chemical correlation. 相似文献
80.
We describe a novel, cost effective and simple technique for the manufacture of high sensitivity absorption cells for microfluidic analytical systems. The cells are made from tinted polymethyl methacrylate (PMMA) in which microfluidic channels are fabricated. Two windows (typically 250 μm thick, resulting in little optical power loss) are formed at either end of the channel through which light is coupled. Unwanted stray light from the emitter passes through a greater thickness of the tinted substrate (typically the length of the cell) and is preferentially absorbed. In effect, this creates a pin-hole configuration over the length of the absorption cell, providing improved performances (sensitivity, S/N ratios, baseline noise and limit of detection) when used as an absorption cell compared to clear substrates. The method is used to achieve a LOD of 20 nM with a colourimetric iron assay and a LOD of 0.22 milli-absorption units with a pH assay. 相似文献