全文获取类型
收费全文 | 153篇 |
免费 | 11篇 |
国内免费 | 28篇 |
专业分类
化学 | 107篇 |
力学 | 27篇 |
物理学 | 28篇 |
综合类 | 30篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 6篇 |
2019年 | 2篇 |
2018年 | 12篇 |
2017年 | 17篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 5篇 |
2013年 | 19篇 |
2012年 | 4篇 |
2011年 | 8篇 |
2010年 | 4篇 |
2009年 | 6篇 |
2008年 | 8篇 |
2007年 | 13篇 |
2006年 | 15篇 |
2005年 | 8篇 |
2004年 | 10篇 |
2003年 | 1篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
排序方式: 共有192条查询结果,搜索用时 15 毫秒
81.
J. V. Hamilton M. B. Schmidt K. W. Greer C. Shah 《Radiation Physics and Chemistry》1998,52(1-6):283-288
In this study, the effects of sterilization dose and atmosphere on UHMWPE wear properties and crosslinking were examined. The relationship between crosslinking and adhesive / abrasive wear mechanisms of acetabular cups was investigated.
The use of a vacuum sterilization atmosphere resulted in improvements in the wear resistance of UHMWPE for the adhesive/abrasive wear mechanisms for the doses examined in this study. The two measures of crosslinking, swelling ratio and gel fraction, values can be used to predict hip simulator wear rates over the sterilization dose range of 0 to 50 kGy for the vacuum atmosphere samples. Of the two measures, the swelling ratio is a more sensitive measure of the extent of crosslinking, particularly for highly crosslinked materials and therefore a more sensitive predictor of adhesive/abrasive wear rates. 相似文献
82.
Hydrogel has been extensively studied for use as articular cartilage. The static and dynamic viscoelasticity behaviors of hydrogel grafted with ultra-high-molecular-weight polyethylene (UHMWPE) were studied by finite-element method (FEM) and dynamic mechanical analysis in this article. The results show that creep deformation presents an exponential function with the pore fluid velocity of hydrogel material. During the first period of stress relaxation, the internal fluid pore pressure of hydrogel material is less than partial pressure, which leads to the increasing fluid exudation, and the stress relaxation rate changes quickly. With the loss of fluid, the pore pressure and partial pressure achieve balance. Then, finally, stress relaxation reaches relative equilibrium. The storage modulus of hydrogel material increases with the increasing frequency, and there is a logarithmic regression between them. With the decrease in liquid–solid ratio, the storage modulus declines, while the loss modulus first increases and then decreases. When the strain increases, both storage modulus and loss modulus show an upward trend. 相似文献
83.
《先进技术聚合物》2018,29(7):1889-1894
In this study, the preparation of ultra‐high molecular weight polyethylene/graphene nanocomposite was carried out using single‐supported Ziegler‐Natta catalyst, and the operational conditions were optimized via response surface methodology. For this purpose, the effect of 3 parameters, monomer pressure, temperature, and molar ratio of [Al] respect to [Ti] on the catalyst productivity and molecular weight of the synthesized nanocomposite polymer, was investigated using the Box‐Behnken experimental design at 3 levels. Monomer pressure, temperature, and molar ratio of [Al] respect to [Ti] were considered as independent variables and catalyst productivity and molecular weight as dependent variables. The highest catalyst productivity and molecular weight were equal to 923 (grPE/mmolTi.h) and 2.04 (million gr/mol), respectively, which were obtained under optimal reaction conditions: temperature of 60°C, pressure of 8 bar, and molar ratio of 185. Finally, in order to investigate the morphology and nanoparticle dispersion in polymer matrix, scanning electron microscope and X‐ray diffraction were used. The results indicate the homogenous dispersion of graphene nanoparticles in polymer matrix. 相似文献
84.
This paper presents an experimental study on the impact behaviour of composite laminates made of a Dyneema® woven fabric and four different resin matrices. Three thicknesses of each kind of resin laminate were subjected to impact by a spherical steel projectile in a velocity regime ranging from 100 to 200 m/s. The results revealed that the laminates having flexible matrices performed much better in perforation resistance and energy absorption, but had a greater extent of deformation and damage than the counterparts with rigid matrices. It was found that the matrix rigidity played a crucial role in controlling the propagation of transverse deformation, and thereby the local strain and perforation resistance of laminates. The more rigid matrix restrained the laminate's transverse deformation to a smaller area at a given time, which led to higher local strain and lower perforation resistance. Fibre failure in tension was identified as the dominant failure mechanism for the tested laminates. 相似文献
85.
Huaming Wang Jingshi Cao Fubin Luo Changlin Cao Qingrong Qian Baoquan Huang Liren Xiao Qinghua Chen 《先进技术聚合物》2019,30(7):1673-1683
In this paper, silicone‐coated intumescent flame retardants was prepared by an efficient and simple approach, aiming at enhancing the flame‐retardant efficiency and smoke suppression properties. The surface of expandable graphite (EG) was treated prior to the coverage of nonflammable silicone. The resultant silicone‐modified EG hybrid (SEG) was combined with ammonium polyphosphate (APP) and applied as a flame‐retardant and smoke‐suppressant for ultrahigh molecular weight polyethylene (UHMWPE). Compared with UHMWPE/APP/EG (with 15 wt% APP/EG), UHMWPE/APP/SEG (with 15 wt% APP/SEG) gives decrement by 18.5% in the peaks of the heat release rate, 6.33% in total heat release and 13.6% in total smoke release, whereas increment by 23% in tensile strength and 12.1% in elongation at break, respectively. It is suggested that the introduction of silicone on the surface of EG can improve the interfacial compatibility between EG and UHMWPE. Moreover, it can lead to forming more char residue and reducing the release of smoke particulates during combustion process of the composites. 相似文献
86.
87.
88.
K. Jacobson 《Polymer Degradation and Stability》2006,91(9):2133-2139
The validity of the total luminescence intensity (TLI) method for determining the amount of hydroperoxides in a UHMWPE sample has been assessed. Measurements of hydroperoxides with FTIR before and after a TLI run showed that only about 50% of the hydroperoxides were decomposed at 150 °C. It was also found that this value was not constant with ageing time, which means that the TLI value could not be representative of the total number of hydroperoxides in a sample as a function of ageing time. Thermoluminescence was also found to complicate the measurements and could, if care was not taken, give TLI values that were much too high. In addition it was found that the TLI value is actually connected with the build-up of carbonyls rather than the build-up of hydroperoxides. This last finding is consistent with part one of this study, where it was reported that CL from oxidising UHMWPE is a type of activated CL, where carbonyls are the activating species. From all of these results it is concluded that TLI is not a suitable method for determining hydroperoxides in UHMWPE. 相似文献
89.
Hironobu Koseki Hiroyuki Shindo Itaru Furuichi Koumei Baba 《Surface and interface analysis : SIA》2008,40(9):1278-1283
Amorphous diamond‐like carbon (DLC) has drawn a great deal of attention for its superior wear properties against ultra‐high molecular weight polyethylene (UHMWPE). Its rate of wear, however, is not necessarily maintained within a specific range. The aim of this study was to evaluate the mechanical features and tribological properties of three types of surfaces: (i) uncoated, (ii) carbon‐ion implantation (CII)‐treated, and (iii) DLC‐film‐coated substrate. The surface alterations were carried out on cobalt–chrome (Co? Cr? Mo) alloy by the plasma‐source ion implantation (PSII) method. The wear properties and friction coefficient were estimated by a pin‐on‐plate wear‐tester. We found, as a result, that the implanted carbon penetrated the substrates in which good adhesion was expected. Though the surface modifications by CII and DLC hardened the surfaces, the surface with DLC was also roughened (Ra = 39 nm). In contrast, the surface modified by CII had a very smooth surface (Ra = 15 nm) and low friction coefficient (ranging from 0.15 to 0.20), resulting in a low rate of wear. Our findings suggest that CII on the Co? Cr? Mo alloy/UHMWPE pair offers potential benefits as a hard coating for artificial total‐joint arthroplasty. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
90.
《Surface and interface analysis : SIA》2018,50(5):558-563
Carbon fibers were coated in an attempt to improve the interfacial properties between carbon fibers and ultra‐high molecular weight polyethylene resin matrix. Atomic force microscopy, scanning electron microscopy, and X‐ray photoelectron spectroscopy were performed to characterize the changes of carbon fiber surface. Atomic force microscopy results show that the coating of carbon fiber significantly increased the carbon fiber surface roughness. X‐ray photoelectron spectroscopy indicates that silicon containing functional groups obviously increased after modification. Interlaminar shear strength was used to characterize the interfacial properties of the composites. 相似文献