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排序方式: 共有92条查询结果,搜索用时 15 毫秒
1.
2.
G. Mascellani L. Liverani A. Prete G. L. Bergonzini P. Bianchini L. Silvestro 《Journal of carbohydrate chemistry》2013,32(8):1165-1177
Abstract The active site of dermatan sulfate (DS) for heparin cofactor II (HCII) was isolated in a fragment obtained by periodate oxidation, borohydride reduction, mild acid hydrolysis, and SE- and SAX-chromatography of beef mucosal and pig skin DS preparations. Characterization by mass spectrometry, one- and two-dimensional NMR spectroscopy, and HPLC analysis of disaccharides, obtained by exhaustive digestion with chondroitinase-ABC, indicates that the fragment has the prevalent structure 1, GalNAc-4SO3-[IdoA-2SO3-GalNAc-4SO3]4-R, where R is CH(CH2OH)CH(COO?)-OH. 1, is the largest DS fragment thus far isolated containing IdoA2SO3 as the only uronic acid. Its lower activity (30%) with respect to the parent polymeric DS is explainable by Tollefsen model, requiring longer polyanionic chains for formation of ternary complex with thrombin. 相似文献
3.
We report the structural and morphological properties of well-aligned ZnO nanowires grown at 750 °C on Au-deposited and annealed
(100)Si substrates using carbo-thermal evaporation. As-grown nanowires are made of wurtzite ZnO, have cylindrical shape and
carry droplet-like nanoparticles (NPs) at their tips, as expected for vapour–liquid–solid (VLS) growth. Grazing incidence
X-ray diffraction measurements demonstrate that the NPs are made of pure fcc Au. No secondary Au/Zn alloy phases were detected.
Bragg diffraction patterns confirmed that the nanowires were grown with their crystal c-axes parallel to the [100] direction
of Si (i.e. normal to the substrate surface), while Au NPs are mostly (111)-oriented. The diameter distribution of ZnO nanowires
mimics that of the Au NPs at their tips. A quantitative study of the nanostructure size distribution after sequential annealing
and growth steps evidences the occurrence of three nanoscale processes: (i) Ostwald ripening and/or coalescence of Au NPs
before nanowire nucleation, (ii) Au-catalysed VLS nucleation and axial growth of ZnO nanowires and (iii) radial growth of
nanowires by a vapour–solid process. These processes originate the NP and nanowire size evolution during the experiments.
The present findings are interpreted in terms of Zn vapour pressure changes during carbo-thermal evaporation.
PACS 61.46.+w; 68.65.-k; 81.16.Dn 相似文献
4.
Spadavecchia J Prete P Lovergine N Tapfer L Rella R 《The journal of physical chemistry. B》2005,109(37):17347-17349
Gold nanoparticles heavily functionalized with oligonucleotides have been used in a variety of DNA detection methods. The optical properties of three-dimensional aggregates of Au nanoparticles in solution or deposited onto suitable surfaces have been analyzed to detect hybridization processes of specific DNA sequences as possible alternatives to fluorescent labeling methods. This paper reports on the preparation of gold nanoparticles directly deposited onto the surface of silicon (Si) and sapphire (Al2O3) substrates by a physical methodology, consisting in the thermal evaporation of a thin Au film and its successive annealing. The method guarantees the preparation of monodispersed single-crystal Au nanoparticles with a strong surface plasmon resonance (SPR) peak centered at about 540 nm. We show that the changes of SPR excitation before and after DNA functionalization and subsequent hybridization of Au nanoparticles immobilized onto Si and Al2O3 substrates can be exploited to fabricate specific biosensors devices in solid phase. 相似文献
5.
L. Biasetto M. Manzolaro A. Andrighetto G. Meneghetti S. Carturan P. Zanonato P. Colombo G. Prete 《The European Physical Journal A - Hadrons and Nuclei》2009,42(3):517-521
The target is one of the key issues of isotope separation on line (ISOL) facilities. SPES, now under development at LNL-INFN,
is an innovative ISOL facility possessing a target chatacterized by seven separate uranium dicarbide thin disks. The research
on the materials development and target prototyping is discussed in the following. 相似文献
6.
7.
G. Viesti B. Fornal F. Gramegna G. Prete R. A. Ricci G. D'Erasmo L. Fiore G. Guarino A. Pantaleo I. Iori A. Moroni P. Blasi F. Lucarelli 《Zeitschrift für Physik A Hadrons and Nuclei》1986,324(2):161-171
The reactions induced by 143 MeV32S on58Ni have been studied detecting discrete γ-rays in coincidence with projectile-like fragments (PLF). Information on PLF excitation probability and sequential decay of target-like fragments (TLF) has been obtained. For the28Si+62Zn outgoing channel at small energy loss (¦Q¦<20 MeV), both PLF and TLF data indicate that thermal equilibrium is not attained. The hypothesis of an equal excitation energy partition between the two reaction fragments does not describe properly experimental TLF data. A dependence of PLF excitation probability on the outgoing channel is found for the two final channels32S+58Ni and28Si+62Zn. The values of the spin alignment parameterP zz, derived for PLF and TLF from measurements ofγ-rays anisotropy, are in disagreement with the expectations of the transport theory for dissipative collisions. 相似文献
8.
D. Scarpa L. Biasetto S. Corradetti M. Manzolaro A. Andrighetto S. Carturan G. Prete P. Zanonato D. W. Stracener 《The European Physical Journal A - Hadrons and Nuclei》2011,47(3):32
In the framework of the R&D program for the SPES (Selective Production of Exotic Species) project of the Istituto Nazionale
di Fisica Nucleare (INFN), production yields of neutron-rich isotopes have been measured at the Holifield Radioactive Ion
Beam Facility (HRIBF, Oak Ridge National Laboratory, USA). This experiment makes use of the multi-foil SPES target prototype
composed of 7 uranium carbide discs, with excess of graphite (ratio C/U = 4 . 77 isotopes of medium mass (between 72 and 141amu), produced via proton-induced fission of uranium using a 40MeV proton
beam, have been collected and analyzed for the target heated at 2000 ° C target temperature. 相似文献
9.
10.
A. Saxena D. Fabris G. Prete D. V. Shetty G. Viesti B. K. Nayak D. C. Biswas R. K. Choudhury S. S. Kapoor M. Lunardon S. Moretto G. Nebbia S. Pesente V. Rizzi A. M. Samant M. Barbui E. Fioretto M. Cinausero A. Brondi G. La Rana R. Moro E. Vardaci N. Gelli F. Lucarelli 《Nuclear Physics A》2004,730(3-4):299-315
Pre-scission and post-scission multiplicities of neutrons and alpha particles have been simultaneously measured for the fission-like reactions of 340 MeV 28Si on 232Th. Dynamical model calculations using HICOL code predict that about 90% of the observed events are of quasi-fission type while the remaining 10% are from compound nucleus fission decay. Moving source fits were carried out to the observed neutron and alpha particle spectra, measured at different angles with respect to the fragment directions. The pre-scission and post-scission neutron multiplicities are deduced to be 8.7±2.0 and 9.4±2.0, respectively. The corresponding multiplicity values for alpha particles are found to be 0.22±0.08 and 0.1±0.03. From the measured post-scission neutron multiplicity, it is inferred that about 65±20 MeV of the initial excitation energy remains at scission. This may be compared to the value of 85±30 MeV estimated from PACE2 statistical model calculations, adjusted to reproduce the measured pre-scission neutron multiplicity. From a comparison of the Statistical Model predictions with the measured pre-scission neutron multiplicity, the fission delay is estimated to be of 5+7−3×10−20 s which overlaps with the average duration of fission-like process from the contact to the scission point (2×10−20 s) as determined from HICOL-based dynamical calculations. For the delay time deduced as above, the pre-scission alpha particle multiplicity calculated by the PACE2 code is about a factor two larger than the experimental one, demonstrating the difficulties in modelling the alpha particle emission from highly elongated shapes that characterize the fissioning system from the contact point to scission. 相似文献