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排序方式: 共有117条查询结果,搜索用时 15 毫秒
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Prof. Giuseppe Alibrandi Dr. Valeria Amendola Dr. Greta Bergamaschi Dr. Riccardo Dollenz Prof. Luigi Fabbrizzi Prof. Maurizio Licchelli Dr. Carmelo Lo Vecchio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(11):3729-3734
The combined activity of the 1.1.1‐cryptand and of a dicopper(II) bistren cryptate complex including chloride makes the Cl? ion be continuously and slowly delivered to the solution, without any external intervention. The 1.1.1‐cryptand slowly releases OH? ions, according to a defined kinetics, and each OH? ion displaces a Cl? ion from the cryptate. Chloride displacement induces a sharp colour change from bright yellow to aquamarine and can be conveniently monitored spectrophotometrically, even in diluted solutions. The 1.1.1‐cryptand is the motor of a molecular dispenser (the dicopper(II) cryptate) delivering chloride ion automatically, from the inside of the solution. 相似文献
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M. Amendola S. Loreti R. Remetti M. Capogni P. L. Carconi M. L. Cozzella P. De Felice A. Fazio F. Pisacane 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(1):109-115
This work deals with the absolute measurement of the neutron emission rate from a 241Am–Be source by means of the manganese sulphate bath technique, which is the principal method for the absolute determination of the neutron emission rate from radionuclide neutron sources. The facility consists of a spherical container filled with an aqueous solution of manganese sulphate with a 241Am–Be neutron source placed at the center. As well known, neutrons from the source, after having been thermalized by the aqueous solution, undergo neutron capture by hydrogen, manganese, sulphur, and oxygen nuclei, thus inducing a certain activity to the solution. Subsequent gamma spectrometry measurements of 56Mn activity generated by 55Mn neutron activation allows to determine the neutron emission rate of the source, The experimental activity has involved a variety of measurement techniques and calculation procedures, ranging from neutron reactor activation to liquid scintillation counting and Monte Carlo calculations. Neutron activations of 55Mn samples has been carried out with the TRIGA reactor of the ENEA-Casaccia Research Centre, and 56Mn activated samples were subsequently characterized by liquid scintillation counting, in order to obtain reference standards for the calibration of the NaI(Tl) scintillation detectors utilized to record gamma-ray emission from 56Mn. Monte Carlo calculations, carried out by the MCNPX code, were required to calculate neutron transport within the sulphate manganese bath, in particular to determine 55Mn neutron capture probability, and (n, α) and (n, p) concurrent reactions, as well as the neutron leakage. Such a procedure has allowed to maintaining the neutron emission rate uncertainty well below 1 %. All the measurements have been carried out at the ENEA-Casaccia Research Centre by the Italian National Institute of Ionizing Radiation Metrology. 相似文献
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Marta Giamberini Eugenio Amendola Cosimo Carfagna 《Macromolecular rapid communications》1995,16(2):97-105
By reacting a rigid rod epoxy terminated molecule (p-bis(2,3-epoxypropoxy)-α-methylstilbene) with an aliphatic carboxylic acid (decanedioic acid), a lightly crosslinked liquid crystalline network is obtained. This network exhibits a smectic-like phase. While the mesophasic structure resulted “frozen” by the crosslinks in the case of higly crosslinked liquid crystalline epoxy resins, in this case a reversible transition from the liquid crystalline to the isotropic phase is observed. Moreover, while curing the same rigid rod epoxy molecule with amines resulted in a thermoset with a nematic structure, in this case a more ordered mesophase can be obtained. Preliminary results show that it is possible to orient macroscopically the mesogenic chains by stretching thin films above the glass transition temperature (Tg) and then quickly cooling down to the glassy state. This makes this material very attractive in the field of optical applications. 相似文献
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Meccanica - This article deals with the mathematical derivation and the validation over benchmark examples of a numerical method for the solution of a finite-strain holonomic (rate-independent)... 相似文献
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Amendola V Fabbrizzi L Mangano C Pallavicini P Roboli E Zema M 《Inorganic chemistry》2000,39(25):5803-5806
The enantiomerically pure bis-imino bis-quinoline ligands R,R-ImQ and S,S-ImQ have been prepared by Schiff condensation of 2-quinoline carboxyaldehyde with the pure R,R and S,S enantiomers of trans-1,2-diaminocyclohexane. Both ligands form 2:2 helical complexes with CuI perchlorate, and the crystal and molecular structure of [Cu2(R,R-ImQ)2]ClO4.H2O have been determined by X-ray diffraction methods: the [Cu2(R,R-ImQ)2]2+ molecular cation is a chiral double helix of M handedness, in which the two ligands are entertwined in such an arrangement that half of each ligand is not equivalent to the other half of the same ligand. Coupled circular dichroism and 1H NMR studies reveal that in CH3CN solution a rearrangement takes place toward a more symmetric helical structure (in which the two halves of the same ligand become equivalent), which maintains the same handedness found in the solid state and is a pure M isomer. Solid state and CH3CN solution CD experiments confirm that [Cu2(S,S-ImQ)2]ClO4.H2O, both in solution and in the solid state, is a pure double helix of P handedness, i.e., the enantiomer of the species containing the R,R ligand. 相似文献
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Amendola V Mangano C Pallavicini P 《Dalton transactions (Cambridge, England : 2003)》2004,(18):2850-2854
Three-component systems made of a tetradentate bis-amino bis-quinoline ligand, a transition metal cation (Ni2+ or Cu2+) and a fluorescent indicator (Coumarin 343) have been studied in a water-dioxane (1 : 4 v/v) mixture, through potentiometric, pH-spectrophotometric and pH-fluorimetric titrations. For the Cu2+ containing systems, an "on-off-on" variation of fluorescence intensity vs. pH has been observed, whereas in the presence of Ni2+ a simple "on-off" profile of the fluorescence intensity vs. pH was obtained. These ternary systems thus behave as window-shaped or conventional pH-indicators, depending whether Cu2+ or Ni2+ is used as the cation. 相似文献