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111.
Abstract In addition to confounding mass-based wear measurements in serum-lubricated hip simulator experiments, fluid absorption by the acetabular cups may simultaneously modify the wear resistance of the ultra-high molecular weight polyethylene (UHMWPE) from which they are composed. To decouple the fluid absorption and wear processes enabling clearer investigation of this effect, absorption was first imposed during an initial stage where UHMWPE was exposed to pressurized (10 MPa) fluid. This was followed by a second stage, where resultant wear behavior was assessed by a multidirectional pin-on-flat technique that, though still providing a serum-lubricating environment, does not promote the simultaneous fluid absorption occurring in hip simulator testing. Both unirradiated and highly crosslinked UHMWPE were investigated, each with both bovine calf serum and water soaking exposures of duration to 129 days. The pressurized soaking of a highly crosslinked UHMWPE decreased its wear resistance, causing an increase in wear rate by approximately 50% during subsequent serum-lubricated multidirectional pin-on-flat sliding tests as compared to non-soaked material. The magnitude of this effect did not appear to depend on whether the soaking fluid was water or serum, nor did it appear to depend on soak time provided it was at least of a 14-day duration, during which more rapid transient fluid absorption occurs. Such soaking did not produce as pronounced an effect on unirradiated UHMWPE, as its lack of wear resistance likely causes the absorption-affected surface region to be removed within the earliest stages of sliding contact. 相似文献
112.
采用差示扫描量热仪(DSC)对含有不同含量超高分子量聚乙烯(UHMWPE)的聚丙烯进行测试和表征,采用Ozawa方法、莫志深方法和Kissinger方法分析了该体系的非等温结晶动力学。利用自行研制的超临界流体挤出发泡实验装置,对含有UHMWPE的PP进行了超临界二氧化碳挤出发泡实验研究。结果表明:超高分子量聚乙烯的加入降低了PP的结晶活化能,含有UHMWPE的PP在较高的温度下开始结晶,且由于超高分子量聚乙烯大分子链的存在,与聚丙烯分子链发生缠结,阻碍聚丙烯分子链排入晶格,降低了结晶速率,结晶温区拓宽,有利于聚丙烯挤出发泡成型;加入UHMWPE后,PP的发泡效果明显改善,泡孔平均直径减小,泡孔尺寸分布更加均匀,PE-UHMW的含量为5份时,表观密度达到0.038g/cm-3。 相似文献
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114.
利用传统的熔融 混合方法制备碳黑填充的聚丙烯 (PP) /超高分子量聚乙烯 (UHMWPE)复合物。当PP/UHMWPE混合比大于 3 / 7,碳黑填充PP/UHMWPE复合物的PTC和NTC效应类似于碳黑填充的纯净PP聚合物。然而当重量比等于或小于 3 / 7时 ,复合物所表现的PTC效应非常相似于碳黑填充的纯净的UHMWPE聚合物。在复合物中应用粘度非常高的聚合物作为一种组分可以有效消除NTC效应 相似文献
115.
The relationships between the mechanical behavior of ultra-high molecular weight polyethylene (UHMWPE) and the long-term clinical performance of acetabular component bearings remain poorly understood. During previous hip simulator validation studies, researchers have correlated the mechanical behavior and surface morphology of polymeric biomaterials with the wear performance in a hip simulator. For the present study, we sought correlations between clinical performance and quantitative metrics of the mechanical behavior and surface morphology of retrieved cups. Nine all-UHMWPE acetabular cups of the same cemented design, 32 mm head size, and manufacturer were retrieved after an average implantation time of 14.1 years (range: 11.5–16.4 years). The implants were manufactured from RCH-1000, sterilized by gamma radiation in air and implanted between 1980 and 1983. Mechanical behavior of the retrieved components was determined using the previously validated small punch test, which subjects miniature specimens to multi-axial loading conditions. Surface morphology of the retrievals was assessed using white light interferometry. No significant relationship was observed between the surface roughness measurements and patient related variables. However, statistically significant relationships were observed between the mechanical behavior determined by the small punch test and the implantation time and patient weight associated with the retrieved hip cups. These findings support the hypothesis that the mechanical behavior of UHMWPE is related, at least in part, to the clinical performance of acetabular component bearings for total hip replacement. 相似文献
116.
UHMWPE/PA1010塑料合金的制备及性能 总被引:1,自引:0,他引:1
采用共辐照接枝法合成UHMWPE-g-AA接枝共聚物;采用共混技术制备UHMWPE/PA1010合金。以UHMWPE-g-AA接枝共聚物作为UHMWPE/PA1010合金增容剂。由于PA1010与UHMWPE-g-AA有较强的相互作用,UHMWPE/PA1010合金的冲击强度和断裂伸长率提高,韧性得到改善;同时,这种相互作用限制了A1010的结晶,使PA1010中正常的结晶含量减少,结晶温度升高。SEM结果表明,增容作用使基体与分散相间界面张力减小,粘结性增强,从而使分散相的粒子尺寸减小,分布更加均匀,拉伸断面显示明显的牵拉现象。共混体系的摩擦系数与纯PA1010相比明显降低,摩擦时在 PA1010表面形成完整UHMWPE的润滑膜,使磨耗量减小,摩擦系数降低。 相似文献
117.
118.
冻胶法制备超高分子量聚乙烯/SiO2杂化微孔膜研究——稀释剂与SiO2对铸膜液熔融结晶性能的影响 总被引:2,自引:0,他引:2
根据界面相分离原理,以矿物油为稀释剂,O2为添加剂,采用冻胶法制备了超高分子量聚乙烯(UHMWPE)膜以及UHMWPE/SiO2杂化微孔膜,讨论了稀释剂以及无机粒子含量对膜熔融结晶性能的影响.结果表明,矿物油作为微孔稀释剂,其加入使微孔膜中UHMWPE熔点降低,结晶度减小.当SiO2与UHMWPE质量比低于8/10时,随SiO2含量增加,UHMWPE熔点变化不显著,熔限增加,结晶温度升高,相对结晶度增大,微晶尺寸减小;当SiO2加入量足够大时,相对结晶度反而减小.随SiO2其含量增加,界面孔增多,膜孔隙率提高,水通量增大,泡点孔径先增大后减小. 相似文献
119.
120.
采用热压固化成型法制得了尺寸范围在9~50μm、密度为0.9413g/cm3、相对分子量为6×106的粉末状超高分子量聚乙烯(UHMWPE)颗粒;并用γ射线平面静止辐照方法,分别用120kGy、250kGy和500kGy剂量辐照样品,辐照剂量率为5kGy/h.采用UMT-Ⅱ多功能摩擦试验机考察了不同辐射剂量下交联UHMWPE的生物摩擦学性能,采用电子扫描电镜(SEM)分析了磨损表面形貌并讨论了其磨损机理.结果表明,辐射剂量为120kGy的UHMWPE磨损率最小,随着辐射剂量的增加,摩擦系数逐渐增大,辐射交联后UHMWPE的摩擦磨损性能均优越于未辐射UHMWPE的摩擦磨损性能. 相似文献