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排序方式: 共有86条查询结果,搜索用时 15 毫秒
71.
Dr. Angel T. Garcia-Esparza Dr. Tatsuya Shinagawa Dr. Samy Ould-Chikh Muhammad Qureshi Dr. Xuyuan Peng Dr. Nini Wei Dr. Dalaver H. Anjum Dr. Alain Clo Dr. Tsu-Chien Weng Dr. Dennis Nordlund Dr. Dimosthenis Sokaras Prof. Jun Kubota Prof. Kazunari Domen Prof. Kazuhiro Takanabe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(21):5874-5878
For overall water-splitting systems, it is essential to establish O2-insensitive cathodes that allow cogeneration of H2 and O2. An acid-tolerant electrocatalyst is described, which employs a Mo-coating on a metal surface to achieve selective H2 evolution in the presence of O2. In operando X-ray absorption spectroscopy identified reduced Pt covered with an amorphous molybdenum oxyhydroxide hydrate with a local structural order composed of polyanionic trimeric units of molybdenum(IV). The Mo layer likely hinders O2 gas permeation, impeding contact with active Pt. Photocatalytic overall water splitting proceeded using MoOx/Pt/SrTiO3 with inhibited water formation from H2 and O2, which is the prevailing back reaction on the bare Pt/SrTiO3 photocatalyst. The Mo coating was stable in acidic media for multiple hours of overall water splitting by membraneless electrolysis and photocatalysis. 相似文献
72.
Molecular dynamics simulations have proven to be accurate in predicting depth distributions of low-energy ions implanted in materials. Free parameters adjusted for every ion-target combination are conventionally used to obtain depth profiles in accordance with the experimental ones. We have previously developed a model for predicting depth profiles in crystalline Si without free parameters. The electronic stopping power was calculated using local total electron density. The model underestimated the stopping in the ?1 1 0? channeling direction. We have now taken a new approach to calculate the electronic stopping power. We use the local valence (3p2) electron density to account for the electronic energy loss between collisions and the Firsov model to account for the electronic energy loss during collision. The lowest electron densities are adjusted with a parametrization that is same for all ions in all implanting directions to correct the problems in the ?1 1 0? channeling direction. 相似文献
73.
Helium (He) is present in fusion reactor wall materials, and its effect on radiation damage must be taken into account. The effect of He on displacement cascades in tungsten (W) has been studied using molecular dynamics simulations. Three different W–W potentials were compared and found to differ, especially for the clustering of the vacancies formed in the cascades. While there are differences in the amounts of damage depending on the potential, the overall effect of He in interstitial positions was to increase the amount of damage, while He in substitutional positions reduces it, due to the effect He has on the recombination of tungsten interstititals. 相似文献
74.
Steven P. Davis Masashi Matsumura Andreia Williams Thomas M. Nordlund 《Journal of fluorescence》2003,13(3):249-259
The fluorescent probe/base, 2-aminopurine (2AP), has been incorporated into DNA pentamers that otherwise contain only adenine, the base that has been shown to stack strongly with itself and with the adenine mimic, 2AP. The probe base has been placed in each of the five positions in single strands. Optical spectral shifts, energy-transfer efficiencies, and their respective temperature dependencies behave simply as a function of 2AP position: those quantities approximately double when 2AP is placed between two adenines, compared to 2AP at either end of the chain. Transfer efficiencies of 80% (at 5°C) are measured for APAAA and AAPAA, 68% for AAAPA, while PAAAA and AAAAP efficiencies are 52% and 46%, respectively (P = 2AP). The spectroscopic parameters are therefore reliable measures of local DNA conformation that can be interpreted in a straightforward manner in terms of interbase electronic interactions. Interactions of 2AP with nonadenine bases have previously been shown to mostly be much weaker. 相似文献
75.
Silje Bøen Torsetnes Marianne Nordlund Broughton Elisabeth Paus Trine Grønhaug Halvorsen Léon Reubsaet 《Analytical and bioanalytical chemistry》2014,406(11):2733-2738
This paper compares two methods to determine the tumor marker progastrin-releasing peptide (ProGRP): as routine assay, the automated time-resolved immunofluorometric assay (TR-IFMA), which allows total ProGRP determination; and the immunocapture liquid chromatography selected reaction monitoring mass spectrometry (LC–SRM-MS) method, which additionally allows isoform differentiation. The investigation included 60 serum samples from patients suffering from various cancer diseases which may cause elevated ProGRP levels (small cell lung carcinoma; SCLC, non-small cell lung carcinoma; NCLC; and medullary thyroid cancer; MTC, as well as some with unspecific diagnosis). The two methods showed good correlation (R 2?=?0.887). However, the MS method determines the total ProGRP concentration systematically approximately 30 % lower than the TR-IFMA, implying that the absolute values generated by the methods are not interchangeable. The MS method gives additional information about isoform levels in the samples, providing novel insight into isoform expression on the protein level. 相似文献
76.
Nordlund D Ogasawara H Bluhm H Takahashi O Odelius M Nagasono M Pettersson LG Nilsson A 《Physical review letters》2007,99(21):217406
We determine electron delocalization rates in liquid water and ice using core-hole decay spectroscopy. The hydrogen-bonded network delocalizes the electrons in less than 500 as. Broken or weak hydrogen bonds--in the liquid or at the surface of ice--provide states where the electron remains localized longer than 20 fs. These asymmetrically bonded water species provide electron traps, acting as a strong precursor channel to the hydrated electron. 相似文献
77.
78.
LG Briquet A Jana L Mether K Nordlund G Henrion P Philipp T Wirtz 《J Phys Condens Matter》2012,24(39):395004
In this paper a new interatomic potential based on the Kieffer force field and designed to perform molecular dynamics (MD) simulations of carbon deposition on silicon surfaces is implemented. This potential is a third-order reactive force field that includes a dynamic charge transfer and allows for the formation and breaking of bonds. The parameters for Si-C and C-C interactions are optimized using a genetic algorithm. The quality of the potential is tested on its ability to model silicon carbide and diamond physical properties as well as the formation energies of point defects. Furthermore, MD simulations of carbon deposition on reconstructed (100) silicon surfaces are carried out and compared to similar simulations using a Tersoff-like bond order potential. Simulations with both potentials produce similar results showing the ability to extend the use of the Kieffer potential to deposition studies. The investigation reveals the presence of a channelling effect when depositing the carbon at 45°?incidence angle. This effect is due to channels running in directions symmetrically equivalent to the (110) direction. The channelling is observed to a lesser extent for carbon atoms with 30°?and 60°?incidence angles relative to the surface normal. On a pristine silicon surface, sticking coefficients were found to vary between 100 and 73%, depending on deposition conditions. 相似文献
79.
Half or full core hole in density functional theory X-ray absorption spectrum calculations of water?
Cavalleri M Odelius M Nordlund D Nilsson A Pettersson LG 《Physical chemistry chemical physics : PCCP》2005,7(15):2854-2858
We analyze the performance of two different core-hole potentials in the theoretical modeling of XAS of ice, liquid and gas phase water; the use of a full core-hole (FCH) in the calculations, as suggested by Hetenyi et al. [B. Hetenyi, F. De Angelis, P. Giamozzi and R. Car, J. Chem. Phys., 2004, 120(18), 8632], gives poor agreement with experiment in terms of intensity distribution as well as transition energies, while the half core hole (HCH) potential, in the case of water, provides a better compromise between initial and final state effects, leading to good agreement with the experimental data. 相似文献