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1.
F. Cataldo Y. Keheyan S. Baccaro 《Journal of Radioanalytical and Nuclear Chemistry》2004,262(2):443-450
Anthracite coal and oil bitumen were submitted to γ-radiation at a total dose of 1 MGy and the radiation-processed samples
were studied by FT-IR spectroscopy, thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The coal samples
were studied also by TGA coupled with FT-IR spectroscopy of the evolved gases. Thermal analysis has revealed a completely
different behavior of the radiolyzed samples in comparison to the unirradiated samples. Both for coal and bitumen significantly
less volatile fraction was released during the TGA and in both cases a significant increase in the amount of carbon coke produced
at 800-900 °C was observed. The radiation processed bitumen increased significantly its ethyl acetate insolubles content.
These results were interpreted in terms of extensive crosslinking and coalification of the samples under the action of γ-radiation.
The results of this study have been applied to the carbonization process of terrestrial sedimentary organic matter which is
commonly attributed to the action of heat flux from the depth of the Earth but which may be also due to the action of natural
radiation. Other application of the results of the present study is to the complex organic matter present on the surfaces
of comets and meteorites. This complex matter was formed by exposure of simple precursors to a field of high energy radiation
for millions or billions of years and is consequently transformed into coal-like and bitumen-like matter. The same arguments
apply to the carbon grains present in the interstellar and circumstellar medium.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Ahlen S Ambrosio M Antolini R Auriemma G Baker R Baldini A Bam BB Barbarino GC Barish BC Battistoni G Bellotti R Bemporad C Bernandini P Bilokon H Bisi V Bloise C Bower C Bussino S Cafagna F Calicchio M Campana D Campana P Carboni M Cecchini S Cei F Chiarella V Cormack R Corona A Coutu S De Cataldo G Dekhissi H De Marzo C De Vincenzi M Di Credico A Diehl E Erriquez O Favuzzi C Ficenec D Forti C Fusco P Giacomelli G Giannini G Giglietto N Giubellino P Grassi M Green P Grillo A Guarino F 《Physical review letters》1994,72(5):608-612
3.
4.
B. Evrard P. Bertholet M. Gueders M. Piette G. Piel D. Cataldo L. Delattre 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):303-308
Ro 28-2653 is a new synthetic inhibitor of matrix metalloproteinases. The ability of these enzymes to degrade various components
of the extracellular matrix seems to play a major role in tumors progression and is potentially effective against bronchial
remodeling in asthma and BPCO. Ro 28-2653 is very poorly soluble in water. This low solubility estimated at about 0.56 μg/ml
in water at 25 °C gives rise to difficulties in pharmaceutical formulation of oral, injectable or nebulizable solutions. The
purpose of our study is to prepare and to characterize inclusion complexes between Ro 28-2653 and cyclodextrins and to investigate
the biopharmaceutical repercussion of the inclusion of the active substance.
The complex formation was investigated by phase solubility studies. 1H-NMR spectroscopy and molecular modeling studies were carried out to elucidate the structure of the inclusion complex between
Ro 28-2653 and cyclodextrin. Oral, intravenous and nebulizable solutions of Ro 28-2653 were developed with cyclodextrin. The
in vivo studies were performed on healthy sheep for the pharmacokinetic evaluation of the oral and intravenous formulations
while the nebulization of the complex solution was studied by using an asthma model in mouse. 相似文献
5.
F. Cataldo Y. Keheyan S. Baccaro 《Journal of Radioanalytical and Nuclear Chemistry》2004,262(2):423-428
Three isomeric chiral terpenes, R(+)-limonene, S(-)-limonene and R(-)-a-phellandrene were γ-radiolyzed in sealed vials at
room temperature with a total radiation dose of 317 kGy. The radiolyzed samples were analyzed by FT-IR, electronic absorption
spectroscopy, liquid chromatography using a diode-array detector (HPLC-DAD) and by polarimetry. Despite a relatively high
radiation dose used, all the chiral molecules selected have shown a low radioracemization rate. This fact and the role played
by the impurities in the selective radio-degradation of one of the two enantiomers has been discussed in the context of the
origin of chirality in prebiotic molecules and the chirality enhancement in a prebiotic world. The results were also discussed
in the frame of the radiosterilization technique of chiral drugs, perfumes and food components.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
Cataldo L Dutan C Misra SK Loss S Grützmacher H Geoffroy M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(11):3463-3468
The EPR spectrum of the novel radical Mes*(CH3)P--PMes* (Mes*=2,4,6-(tBu)3C6H2) was measured in the temperature range 100-300 K, and was found to be drastically temperature dependent as a result of the large anisotropy of the 31P hyperfine tensors. Below 180 K, a spectrum of the liquid solution is accurately simulated by calculating the spectral modifications due to slow tumbling of the radical. To achieve this simulation, an algorithm was developed by extending the well-known nitroxide slow-motion simulation technique for the coupling of one electron spin to two nuclear spins. An additional dynamic process responsible for the observed line broadening was found to occur between 180 K and room temperature; this broadening is consistent with an exchange between two conformations. The differences between the isotropic 31P couplings associated with the two conformers are shown to be probably due to an internal rotation about the P--P bond. 相似文献
7.
The radiolysis of β(−)pinene has been studied at five different radiation dose, namely at 50, 100, 150, 300 and 600 kGy with
a dose rate of 2.2 kGy/h. At lower radiation dose, β(−)pinene showed a reduction of the optical activity, hence, the expected
radioracemization appeared predominant. At higher radiation dose, an opposite and unexpected trend was observed: the optical
activity increased almost linearly with the radiation dose. The increase of [α]D of radiolyzed β(−)pinene was due to the formation oligomers, mainly a dimer and/or a trimer of β(−)pinene which remain soluble
in the monomer but which displayed a higher optical activity than the starting monomer, contributing to the increase in the
specific optical rotation. Simultaneously to the formation of the dimer/trimer the radiolysis of β(−)pinene induced also its
polymerization into a poly(β(−)pinene) resin which was insoluble in the monomer and which was characterized by a high structural
order and by the preservation of the chiral centers so that it showed an enhanced specific optical rotation which is ≈2 times
that of the monomer. It is shown that poly(β(−)pinene) radiopolymer can be easily racemized in presence of a Friedel-Crafts
catalyst. The kinetics of β(−)pinene radiation-induced oligomerization and polymerization can be described by a pseudofirst
order rate constant k = 1.9·10−7·s−1. The radiation chemical yield for the same reaction is G = 1.93·10−6 mol/J. The work shows that also the radiation-induced polymerization of chiral monomers may be a tool for the preservation
and amplification of the optical activity of the monomer with implications for abiotic mechanisms of chiral amplification. 相似文献
8.
Franco Cataldo 《Polymer Degradation and Stability》1998,60(2-3):233-237
Free-standing films of cis-transoidal polyphenylacetylene, when treated with ozonized air at 1–2% by weight O3 concentration, undergo a cis-trans isomerization induced by ozone as shown by electronic spectra. Moreover, the presence of the radical cation of polyphenylacetylene can be observed during ozone addition. The cis-trans isomerization is also confirmed by FT-IR spectra of polyphenylacetylene ozonized in solution. Hydroperoxidic groups, as well as peroxidic and aldehydic, are observed by FT-IR spectroscopy on ozonized polyphenylacetylene; in addition, ozonide groups are clearly present. The kinetics of ozonization of cis-transoid and trans-cisoid polyphenylacetylene was followed by electronic spectroscopy. The curves obtained as a function of ozonization time have a characteristic sigmoid shape. Polyphenylacetylene reacts more slowly with ozone than with the isolated double bonds of cis-1,4-polyisoprene, and thus it cannot act as an antiozonant. 相似文献
9.
Iodice M Cusanno F Acha A Ambrozewicz P Aniol KA Baturin P Bertin PY Benaoum H Blomqvist KI Boeglin WU Breuer H Brindza P Bydzovský P Camsonne A Chang CC Chen JP Choi S Chudakov EA Cisbani E Colilli S Coman L Craver BJ De Cataldo G de Jager CW De Leo R Deur AP Ferdi C Feuerbach RJ Folts E Fratoni R Frullani S Garibaldi F Gayou O Giulani F Gomez J Gricia M Hansen JO Hayes D Higinbotham DW Holmstrom TK Hyde CE Ibrahim HF Jiang X Kaufman LJ Kino K Kross B Lagamba L LeRose JJ Lindgren RA 《Physical review letters》2007,99(5):052501
An experiment measuring electroproduction of hypernuclei has been performed in hall A at Jefferson Lab on a 12C target. In order to increase counting rates and provide unambiguous kaon identification two superconducting septum magnets and a ring imaging Cherenkov detector were added to the hall A standard equipment. An unprecedented energy resolution of less than 700 keV FWHM has been achieved. Thus, the observed (Lambda)(12)B spectrum shows for the first time identifiable strength in the core-excited region between the ground-state s-wave Lambda peak and the 11 MeV p-wave Lambda peak. 相似文献
10.
F. Cataldo 《Journal of Radioanalytical and Nuclear Chemistry》2007,272(1):107-113
The terpenes α-(+)-pinene, and α-(−)pinene have been radiolyzed at radiation doses of 150, 300 and 600 kGy. The radiolyzed
samples have been analyzed by FT-IR spectroscopy and polarimetry. Both α-(+)-, α-(−)-pinenes show a linear trend to radioracemization
as a function of the radiation dose administered ≈2.5·10−3 [α]D/kGy. The solvent fractionation and the liquid chromatographic analysis (HPLC) of the radiolyzed samples shows that both α-pinene
enantiomers produce ocimene and dipentene together with minor quantities of other products and a resin. The kinetics of α-pinene
decomposition under radiolytic conditions can be described by a pseudofirst order rate constant k∼5.3·10−7s−1 while the radiation chemical yield for the same reaction has a G = 5.0 molecules/100 eV, so that about 30% of the original α-pinene is converted into other products at 600 kGy. 相似文献