全文获取类型
收费全文 | 461篇 |
免费 | 5篇 |
国内免费 | 36篇 |
专业分类
化学 | 85篇 |
晶体学 | 8篇 |
力学 | 80篇 |
综合类 | 1篇 |
数学 | 3篇 |
物理学 | 233篇 |
综合类 | 92篇 |
出版年
2024年 | 3篇 |
2023年 | 4篇 |
2022年 | 10篇 |
2021年 | 10篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 13篇 |
2017年 | 7篇 |
2016年 | 15篇 |
2015年 | 14篇 |
2014年 | 23篇 |
2013年 | 21篇 |
2012年 | 35篇 |
2011年 | 43篇 |
2010年 | 29篇 |
2009年 | 39篇 |
2008年 | 33篇 |
2007年 | 28篇 |
2006年 | 26篇 |
2005年 | 5篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2002年 | 11篇 |
2001年 | 10篇 |
2000年 | 18篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 13篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 15篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有502条查询结果,搜索用时 15 毫秒
51.
52.
From the thermodynamical, optical texture and dielectric studies of the binary mixtures of 3β-chloro-5-cholestene (ChCl) and 4-n-decyloxybenzoic acid (DOBA), the phase diagram has been drawn. It has been observed that low concentrations of ChCl (1 to 7 mol%) in DOBA induce various types of twisted grain boundary (TGB) submesophases, whereas higher concentrations induce a smectic A (SmA) mesophase. Various optical textures of the TGB phases under different conditions of molecular anchoring have been observed. Weak transitions related with TGB phases have been detected from the temperature dependence of dielectric permittivity. The observed phase diagram of ChCl-DOBA binary system is in complete conformity with the theoretically predicted mean-field phase diagram derived by Renn within the framework of the chiral Chen-Lubenski model 相似文献
53.
Susumu Onaka 《哲学杂志》2020,100(13):1703-1715
54.
In this paper we introduce a peridynamic model for the evolution of damage from pitting corrosion capable of capturing subsurface damage. We model the anodic reaction in corrosion processes (in which electroplating is negligible) as an effective peridynamic diffusion process in the electrolyte/solid system coupled with a phase-change mechanism that allows for autonomous evolution of the moving interface. In order to simulate creation of subsurface damage, we introduce a corrosion damage model based on a stochastic relationship that connects the concentration in the metal to the damage of peridynamic mechanical-bonds that are superposed onto diffusion-bonds. We study convergence of this formulation for diffusion-dominated stage. The model leads to formation of a subsurface damage layer, seen in experiments. We validate results against experiments on pit growth rate and polarization data for pitting corrosion. We extend the 1D model to the 2D and 3D, and introduce a new damage-dependent corrosion model to account for broken mechanical bonds that enhance the corrosion rate. This coupled model can predict the pit shape and damage profile in materials with microstructural heterogeneities, such as defects, interfaces, inclusions, and grain boundaries. 相似文献
55.
《Physics letters. A》2019,383(22):2652-2657
The equilibrated grain boundary groove shape of solid Al in equilibrium with Al-Sn-Mg eutectic liquid was observed by using a Bridgman type directional solidification apparatus. The ratio of the thermal conductivity of the equilibrated liquid to the thermal conductivity of solid Al has been obtained as 0.91. In addition, the average Gibbs-Thomson coefficient, , the solid-liquid interfacial energy, and the grain boundary energy, , in the Al/Al-Sn-Mg system have been calculated from the measured grain boundary shapes. 相似文献
56.
O. V. Cherstiouk A. N. Gavrilov L. M. Plyasova I. Yu. Molina G. A. Tsirlina E. R. Savinova 《Journal of Solid State Electrochemistry》2008,12(5):497-509
Structural defects play major role in catalysis and electrocatalysis. Nanocrystalline (or nanostructured) materials composed
of nanometer-sized crystallites joined via grain boundaries have been recognized for their specific structure and properties,
differentiating them from single crystals, coarsely grained materials or nanometer-sized supported single-grained particles
(Gleiter, Nanostruct Mater 1:1–19, 1992). In this paper, we use Pt electrodes, prepared by electrodeposition on glassy carbon and gold supports, as model nanocrystalline
materials to explore the influence of grain boundaries and other structural defects on electrocatalysis of CO and methanol
oxidation. We build on the recently established correlations between the nanostructure (lattice parameter, grain size, and
microstrains) of electrodeposited Pt and the deposition potential (Plyasova et al., Electrochim. Acta 51:4447–4488, 2006) and use the latter to obtain materials with variable density of grain boundary regions. The activity of electrodeposited
Pt in the oxidation of methanol and adsorbed CO exceeds greatly that for Pt(111), polycrystalline Pt, or single-grained Pt
particles. It is proposed that active sites in nanostructured Pt are located at the emergence of grain boundaries at the surface.
For methanol electrooxidation, the electrodes with optimal nanostructure exhibit relatively high rates of the “direct” oxidation
pathway and of the oxidation of strongly adsorbed poisoning intermediate (COads), but not-too-high methanol dehydrogenation rate constant. These electrodes exhibit an initial current increase during potentiostatic
methanol oxidation explained by the COads oxidation rate constant exceeding the methanol decomposition rate constant.
相似文献
E. R. SavinovaEmail: |
57.
Dr. Xiaofei Yang Dr. Xuejie Gao Dr. Ming Jiang Dr. Jing Luo Jitong Yan Jiamin Fu Dr. Hui Duan Dr. Shangqian Zhao Prof. Yongfu Tang Dr. Rong Yang Ruying Li Prof. Jiantao Wang Dr. Huan Huang Prof. Chandra Veer Singh Prof. Xueliang Sun 《Angewandte Chemie (International ed. in English)》2023,62(5):e202215680
Sulfide electrolytes with high ionic conductivities are one of the most highly sought for all-solid-state lithium batteries (ASSLBs). However, the non-negligible electronic conductivities of sulfide electrolytes (≈10−8 S cm−1) lead to electron smooth transport through the sulfide electrolyte pellets, resulting in Li dendrite directly depositing at the grain boundaries (GBs) and serious self-discharge. Here, a grain-boundary electronic insulation (GBEI) strategy is proposed to block electron transport across the GBs, enabling Li−Li symmetric cells with 30 times longer cycling life and Li−LiCoO2 full cells with three times lower self-discharging rate than pristine sulfide electrolytes. The Li−LiCoO2 ASSLBs deliver high capacity retention of 80 % at 650 cycles and stable cycling performance for over 2600 cycles at 0.5 mA cm−2. The innovation of the GBEI strategy provides a new direction to pursue high-performance ASSLBs via tailoring the electronic conductivity. 相似文献
58.
The grain boundary plays an important role in the electrical behaviors of solid oxide electrolytes for solid state fuel cells. To reveal the relationship between the structure and the ionic conductivity of grain boundary,the conductive properties of {1 1 1} and {1 1 0} twist grain boundaries in 8 mol% yttria-stabilized zirconia have been examined. These boundaries have a series of Σ values defined by the coincident site lattice model. It has been found that the activation energy of {1 1 1} twist grain boundary increases and then decreases with the Σ value,while that of the {1 1 0} boundary shows an opposite trend. It is suggested that the properties can reflect the balance of the effects of lattice mismatch on the diffusion ability of oxygen vacancies and the segregation of oxygen vacancies and Y3 tions. Therefore,the properties in polycrystalline electrolyte can be adjusted by controlling the grain boundary structures. 相似文献
59.
60.
T. Striffler U. Stuhr H. Wipf H. Hahn S. Egelhaaf 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(2):245-251
By means of small-angle neutron scattering the microstructure of two nanocrystalline Pd samples (prepared by inert gas condensation)
has been studied at room temperature in a Q-range from [0pt] to [0pt] . An additional subsequent doping of the two samples with H as well as with D (concentrations < 4 at%) caused contrast variations
that provided more detailed structural information. The measured scattering intensity was modeled by a Porod contribution
from large heterogenities (e.g. pores) and a contribution from spherical grains with a log-normal distribution of their radii. To account for the presence
of grain boundaries, the grains were considered to be surrounded by a shell with a reduced Pd density and a thickness half
as large as the thickness of the grain boundaries. For the above model, the data of the H-doped, D-doped and undoped sample
were simultaneously fitted with one single set of adjustable parameters. The fits yielded for the two samples volume-weighted
mean grain radii of 10 nm and 13 nm. The values for the grain boundary thickness lie between 0.2 and 0.8 nm. Almost all of
the H- and D-atoms are, at low hydrogen concentrations, located in the grain boundaries.
Received 1 May 2000 相似文献