全文获取类型
收费全文 | 190篇 |
免费 | 5篇 |
国内免费 | 4篇 |
专业分类
化学 | 64篇 |
晶体学 | 2篇 |
力学 | 4篇 |
数学 | 13篇 |
物理学 | 116篇 |
出版年
2023年 | 3篇 |
2022年 | 1篇 |
2019年 | 3篇 |
2018年 | 4篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 6篇 |
2013年 | 45篇 |
2012年 | 4篇 |
2011年 | 6篇 |
2010年 | 7篇 |
2009年 | 8篇 |
2008年 | 5篇 |
2007年 | 13篇 |
2006年 | 11篇 |
2005年 | 8篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1991年 | 7篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 4篇 |
1974年 | 1篇 |
排序方式: 共有199条查询结果,搜索用时 15 毫秒
31.
Correlation between deformation bleaching and mechanoluminescence in coloured alkali halide crystals
The present paper reports the correlation between deformation bleaching of coloration and mechanoluminescence (ML) in coloured
alkali halide crystals. When the F-centre electrons captured by moving dislocations are picked up by holes, deep traps and other compatible traps, then deformation
bleaching occurs. At the same time, radiative recombination of dislocation captured electrons with the holes gives rise to
the mechanoluminescence. Expressions are derived for the strain dependence of the density of colour centres in deformed crystals
and also for the number of colour centres bleached. So far as strain, temperature, density of colour centres, E
a and volume dependence are concerned, there exists a correlation between the deformation bleaching and ML in coloured alkali
halide crystals. From the strain dependence of the density of colour centres in deformed crystals, the value of coefficient
of deformation bleaching D is determined and it is found to be 1.93 and 2.00 for KCl and KBr crystals, respectively. The value of (D+χ) is determined from the strain dependence of the ML intensity and it is found to be 2.6 and 3.7 for KCl and KBr crystals,
respectively. This gives the value of coefficient of deformation generated compatible traps χ to be 0.67 and 1.7 for KCl and KBr crystals, respectively. 相似文献
32.
33.
The problem of peristaltic flow of a Newtonian fluid with heat transfer in a vertical asymmetric channel through porous medium is studied under long-wavelength and low-Reynolds number assumptions. The flow is examined in a wave frame of reference moving with the velocity of the wave. The channel asymmetry is produced by choosing the peristaltic wave train on the walls to have different amplitudes and phase. The analytical solution has been obtained in the form of temperature from which an axial velocity, stream function and pressure gradient have been derived. The effects of permeability parameter, Grashof number, heat source/sink parameter, phase difference, varying channel width and wave amplitudes on the pressure gradient, velocity, pressure drop, the phenomenon of trapping and shear stress are discussed numerically and explained graphically. 相似文献
34.
35.
J. Araña J.M. Doña Rodríguez O. González Díaz J.A. Herrera Melián J. Pérez Peña 《Applied Surface Science》2006,252(23):8193-8202
The photocatalytic mineralization of methanol, ethanol and 1-propanol is compared with those of their homologous carboxylic acids (formic, acetic and propanoic). The presence of S2O82− ions almost does not affect the alcohols mineralization. But, those of the acids are slowed down. In addition to this, adding H2O2 inhibits the alcohols mineralization and those of the acids, but to a lesser extent.FT-IR studies have shown that carboxylates generated from the oxidation of the corresponding alcohols adsorb at different centres from those where carboxylates directly generated from formic, acetic and propanoic acids do.From the obtained results, mineralizations of these compounds have been correlated with their proximity and accessibility to photoactive centres. 相似文献
36.
The absorption cross-section integral and the oscillator strength of the 960 nm absorption band due to F2
– colour centres in LiF crystal is determined at room temperature from the absorption cross-section spectrum of the F2
– centres obtained from saturable absorption studies. A comparison with previous results is made. 相似文献
37.
本文通过对电子陷获型红外上转换材料的激发光谱和发光光谱特性曲线的测试,论证该材料与一般红外器件相比,具有响应光谱范围广(0.8~1.6μm)等优点,为该材料的推广应用提供了可靠的依据。 相似文献
38.
We discuss theoretical work on motion-limited trapping kinetics at very low temperatures where theories based upon strictly diffusive models break down due to quantum mechanical effects. In addition, we present numerical results which confirm earlier asymptotic predictions regarding the survival probability for one-dimensional chains, and discuss the important role fluctuations and selfaveraging (or the lack thereof) play in the analysis of finite systems. 相似文献
39.
J. Nawrocki 《Chromatographia》1991,31(3-4):177-192
Summary The review describes many different controversies concerning the surface chemistry of silica. The first part concerns the variable nature of alkyl bonded phases for HPLC, the physical requirements for silica and the role of silanols as adsorption centres. The existence of a small population of strong adsorption sites is pointed out and the reasons for the strong and undesirable adsorption discussed; the part played by trace metals in the silica matrix is emphasised. 相似文献
40.
Optimised hydrothermal synthesis of multi-dimensional hybrid coordination polymers containing flexible organic ligands 总被引:2,自引:0,他引:2
Filipe A. Almeida Paz Joo Rocha Jacek Klinowski Tito Trindade Fa-Nian Shi Luís Mafra 《Progress in Solid State Chemistry》2005,33(2-4):113-125
In this paper, we summarise our recent research interest in the hydrothermal synthesis and structural characterisation of multi-dimensional coordination polymers. The use of N-(phosphonomethyl)iminodiacetic acid (also referred to as H4pmida) in the literature as a versatile chelating organic ligand is briefly reviewed. This molecule plays an important role in the formation of centrosymmetric dimeric [V2O2(pmida)2]4− anionic units, which were first used by us as building blocks to construct novel coordination polymers. Starting with [V2O2(pmida)2]4− in solution, we have isolated [M2V2O2(pmida)2(H2O)10] species (where M2+ = Mn2+, Co2+ or Cd2+) via the hydrothermal synthetic approach, which were then employed for the construction of [CdVO(pmida)(4,4′-bpy)(H2O)2]·(4,4′-bpy)0.5·(H2O), [CoVO(pmida)(4,4′-bpy)(H2O)2]·(4,4′-bpy)0.5, [Co(H2O)6][CoV2O2(pmida)2(pyr)(H2O)2]·2(H2O) and [Cd2V2O2(pmida)2(pyr)2(H2O)4]·4(H2O) by the inclusion of bridging organic ligands in the reactive mixtures, such as pyrazine (pyr) and 4,4′-bipyridine (4,4′-bpy). These materials can contain channel systems, and exhibit magnetic behaviour, not only due to the V4+ centres but also to the transition metal centres which establish the links between neighbouring dimeric [V2O2(pmida)2]4− anionic units. A closely related anionic moiety, [Ge2(pmida)2(OH)2]2−, was engineered to allow the study of such crystalline hybrid materials using one- and two-dimensional high-resolution solid-state NMR. 相似文献