全文获取类型
收费全文 | 60篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
化学 | 29篇 |
力学 | 5篇 |
数学 | 23篇 |
物理学 | 8篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2013年 | 3篇 |
2012年 | 2篇 |
2011年 | 1篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 8篇 |
2001年 | 2篇 |
1999年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1940年 | 1篇 |
1937年 | 2篇 |
1935年 | 2篇 |
1932年 | 1篇 |
排序方式: 共有65条查询结果,搜索用时 15 毫秒
51.
D. Bikiaris A. Vassiliou K. Chrissafis K.M. Paraskevopoulos A. Jannakoudakis A. Docoslis 《Polymer Degradation and Stability》2008,93(5):952-967
The effect of acid treatment of multi-walled carbon nanotubes (MWCNTs) on the mechanical, thermal and mainly thermo-oxidative stability of isotactic polypropylene (iPP) was evaluated. From the acid treatment surface carboxylic groups were mainly formed, while the nanotubes' length was gradually reduced by increasing the treatment time. Young's modulus, tensile strength and storage modulus of the iPP/MWCNT nanocomposites were increased by increasing the treatment time of the MWCNTs, due to finer dispersion inside the polymer matrix, as revealed by TEM and micro-Raman spectroscopy. Furthermore, the nanotubes acted as nucleating agents, an effect more pronounced with finer filler dispersion. Thermal stability in an inert atmosphere also increased. Thermo-oxidative stability tests in air and O2 revealed that oxidative degradation took place in two stages. In the first stage, corresponding to temperatures up to 230 °C, the MWCNTs accelerated the oxidation of iPP, while at higher than 300 °C temperatures the trend was reversed. Incubation studies proved that, at the first stages, oxidation was due to random chain scission of iPP and oxygen uptake. This behaviour was accelerated by the MWCNTs' surface carboxylic groups and, as found by O2 permeability studies, was mainly a surface process. In the second stage, due to the shielding effect of MWCNTs, the removal of the gases produced during decomposition was hindered. At this stage the presence of MWCNTs resulted in more thermo-oxidatively stable nanocomposites. 相似文献
52.
O. Papadopoulou J. Novakovic P. Vassiliou E. Filippaki Y. Bassiakos 《Applied Physics A: Materials Science & Processing》2013,113(4):981-988
Three representative ancient-like bronzes are employed for the chemical synthesis of Cu2(OH)3Cl rich patinas in order to study the influence of the alloying elements in the evolution of the chloride attack and to further conduct stabilization treatment via Hydrogen Glow Discharge Plasma (HGDP) at low temperature and pressure. The corrosion behavior of specimens having Sn and Pb as main alloying elements is governed by a decuprification mechanism and by the formation of Sn–Pb–O enriched barrier layers. In the case of the Zn containing alloy, dezincification is more pronounced at the corrosion initial stages, and copper species predominate the corrosion products evolution. A three-hour HGDP treatment leads to Cu+ production and metallic Cu, Sn, Zn, and Pb redeposition, as a result of metal cation reduction. This process is accompanied by partial removal of Cl species, O diminution, and change in coloration. The further increase of the Cl/O atomic ratio measured on the post-treated surfaces leads to the formation of nantokite and thus to the conclusion that the stabilization of objects with extensive Cl attack is not feasible by HGDP without preliminary chemical treatment. 相似文献
53.
Nondisruptive Dissolution of Hyperpolarized 129Xe into Viscous Aqueous and Organic Liquid Crystalline Environments
下载免费PDF全文
![点击此处可从《Angewandte Chemie (International ed. in English)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ashley E. Truxal Clancy C. Slack Muller D. Gomes Dr. Christophoros C. Vassiliou Prof. Dr. David E. Wemmer Prof. Dr. Alexander Pines 《Angewandte Chemie (International ed. in English)》2016,55(15):4666-4670
Studies of hyperpolarized xenon‐129 (hp‐129Xe) in media such as liquid crystals and cell suspensions are in demand for applications ranging from biomedical imaging to materials engineering but have been hindered by the inability to bubble Xe through the desired media as a result of viscosity or perturbations caused by bubbles. Herein a device is reported that can be reliably used to dissolve hp‐129Xe into viscous aqueous and organic samples without bubbling. This method is robust, requires small sample volumes (<60 μL), is compatible with existing NMR hardware, and is made from readily available materials. Experiments show that Xe can be introduced into viscous and aligned media without disrupting molecular order. We detected dissolved xenon in an aqueous liquid crystal that is disrupted by the shear forces of bubbling, and we observed liquid‐crystal phase transitions in (MBBA). This tool allows an entirely new class of samples to be investigated by hyperpolarized‐gas NMR spectroscopy. 相似文献
54.
Chitosan derivatives as biosorbents for basic dyes 总被引:1,自引:0,他引:1
Lazaridis NK Kyzas GZ Vassiliou AA Bikiaris DN 《Langmuir : the ACS journal of surfaces and colloids》2007,23(14):7634-7643
The scope of this study was to prepare and evaluate chitosan derivatives as biosorbents for basic dyes. This was achieved by grafting poly (acrylic acid) and poly (acrylamide) through persulfate induced free radical initiated polymerization processes and covalent cross-linking of the prepared materials. Remacryl Red TGL was used as the cationic dye. Equilibrium sorption experiments were carried out at different pH and initial dye concentration values. The experimental equilibrium data for each adsorbent-dye system were successfully fitted to the Langmuir, Freundlich and pH-dependent Langmuir-Freundlich sorption isotherms. Thermodynamic parameters of the adsorption process such as DeltaG degrees, DeltaH degrees, and DeltaS degrees were calculated. The negative values of free energy reflected the spontaneous nature of adsorption. The typical dependence of dye uptake on temperature and the kinetics of adsorption indicated the process to be chemisorption. The grafting modifications greatly enhanced the adsorption performance of the biosorbents, especially in the case of powdered cross-linked chitosan grafted with acrylic acid, which exhibited a maximum adsorption capacity equal to 1.068 mmol/g. Kinetic studies also revealed a significant improvement of sorption rates by the modifications. Diffusion coefficients of the dye molecule were determined to be of the order 10(-13) - 10(-12) m2/s. Furthermore, desorption experiments affirmed the regenerative capability of the loaded material. 相似文献
55.
Katsiaouni S Dechert S Brückner C Meyer F 《Chemical communications (Cambridge, England)》2007,(9):951-953
This contribution describes the synthesis of a novel pyrazole-pyrrole building block and its use in the formation of a non-aromatic, Schiff base-type macrocycle incorporating a chromophore and H-bonding donor and acceptor functionalities inside and outside of the macrocycle, which makes it predestined for molecular recognition systems. 相似文献
56.
Efstathios Vassiliou 《Rendiconti del Circolo Matematico di Palermo》2013,62(3):393-408
Local connection forms provide a very useful tool for handling connections on principal bundles, because, essentially, they involve only the adjoint representation and the left (logarithmic) differential of the structure group, thus overcoming any complexities of the total space. The main results here characterize connections related together by bundle morphisms. A few applications refer to connections on (Banach) associated bundles and connections on projective limit bundles (in the Fréchet framework). The role of local connection forms is further illustrated by their sheaf-theoretic globalization, resulting in a sheaf-theoretic approach to principal connections. The latter point of view is naturally leading to a theory of connections on abstract principal sheaves. 相似文献
57.
Stereochemistry is information, and stereoselective reactions are the means by which that information may be communicated within and between molecules. The control of remote stereogenic centres can be achieved by stereochemical relay, and the use of thermodynamic control over conformational preference is turning out to be a very powerful method for long-range transmission of stereochemical information. 相似文献
58.
Peter J. Vassiliou 《Differential Geometry and its Applications》2006,24(4):332-350
We provide necessary and sufficient conditions on the derived type of a vector field distribution V in order that it be locally equivalent to a partial prolongation of the contact distribution , on the 1st order jet bundle of maps from R to Rq, q?1. This result fully generalises the Goursat normal form from the theory of exterior differential systems. Our proof is constructive: it is proven that if V is locally equivalent to a partial prolongation of then the explicit construction of contact coordinates algorithmically depends upon the integration of a sequence of geometrically defined and algorithmically determined integrable Pfaffian systems on M. Though the tools required are rather different, our main theorem may be regarded as a generalisation of the work of R.B. Gardner and W.F. Shadwick on the feedback linearisation of autonomous nonlinear control systems. 相似文献
59.
P.-C. G. Vassiliou 《The Journal of the Operational Research Society》1981,32(6):503-506
The literature on supply models for manpower planning shows that an important consideration is the size of the discrepancy between the age or length of service distribution of the population and the age distribution which would be reached if present policies were continued indefinitely. In the present paper we study the asymptotic behaviour of the age distribution in any manpower system. An application to a decision problem in a university system is given. 相似文献
60.
The local supercluster of galaxies (LSG) is considered as an expanding region inside a vacuole which is itself embedded in a Friedmann model. It is shown that de Vaucouleurs' data for the LSG can be accounted for by this inhomogeneous cosmological model. On the contrary, the interpretation of these observations would meet some difficulty with a theory of tired light.Dedicated to Achille Papapetrou on the occasion of his retirement. 相似文献