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51.
Nuno Calçada Loureiro Satyabrata Ghosh Júlio C. Viana José Luis Esteves 《Polymer-Plastics Technology and Engineering》2015,54(4):350-356
In this work we present the thermal characterization of the full scope of polyhydroxyalcanoate and poly(lactic acid) blends obtain by injection molding. Blends of polyhydroxyalcanoate and poly(lactic acid) (PHA/PLA) were prepared in different compositions ranging from 0–100% in steps of 10%. The blends were injection molded and then characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD). The increment of PHA fraction increased the degree of crystallinity of the blend and the miscibility of the base polymers as verified by the Fox model. The WAXD analysis indicates that the presence of PHA hindered the PLA crystallization. The crystallization evolution trough PHA weight fraction (wf) shows a phase inversion around 50-60%. SEM analyses confirmed that the miscibility of PHA/PLA blends increased with the incorporation of PHA and became total for values of PHA higher that 50%. 相似文献
52.
全淀粉生物降解塑料技术研究现状 总被引:3,自引:1,他引:2
阐述了淀粉基生物降解塑料的研究现状及发展趋势;重点介绍了全淀粉生物降解塑料技术,从天然淀粉材料本身的多种理化特性着手,对全淀粉塑料的研究背景、现状、特点进行了较为全面的论述;并在此基础上总结归纳出了其今后的发展趋势。 相似文献
53.
54.
研究了快速鉴别可降解一次性塑料制品成分的方法。首先利用衰减全反射红外光谱方法采集市场常见生物降解塑料的红外光谱图,作为标准对照谱图。然后收集市场一次性可降解塑料制品,包括塑料袋、餐盒、餐具、杯子、吸管等,用手术刀切下制品薄层,采用衰减全反射红外光谱法对薄层进行表征,结合生物降解塑料标准对照谱图及常见塑料填料标准谱图确定一次性塑料制品成分。在此基础上选择有代表性的一次性塑料制品的红外谱图,建立一次性可降解塑料制品标准红外谱图库。结果表明:采集样品材质可分三大类,分别以聚乳酸、淀粉、聚对苯二甲酸/己二酸/丁二酯为主体添加适当填料。未知样品与谱库数据匹配度,可作为未知样品的初步判定依据。可见通过红外光谱衰减全反射分析方法可以对可降解一次性塑料制品材质成分进行分析,该方法无需前处理,操作简单,为大批量可降解包装制品检测提供了一种简便、快捷、准确的方法。 相似文献
55.
56.
Novel sol-gel derived calcium phosphate coatings on Mg4Y alloy 总被引:1,自引:0,他引:1
Abhijit RoySatish S. Singh Moni Kanchan DattaBoeun Lee J. OhodnickiPrashant N. Kumta 《Materials Science and Engineering: B》2011,176(20):1679-1689
Calcium phosphates (CaPs) and silicon containing calcium phosphates (Si-CaPs) coatings on a biodegradable magnesium yttrium alloy (Mg4Y) were prepared by a sol-gel technique to improve the bioactivity of the alloy surface. The experimental results show that thick porous coatings comprised of nano-sized calcium phosphate particles can be prepared by heating the as dip coated substrates at 450 °C. The in vitro degradation results show that the coatings do not alter the degradation kinetics of the substrates significantly and the release of magnesium and yttrium ions at initial time points was very similar for both the coated and bare substrates. The cyto-compatibility studies using MC3T3-E1 osteoblasts show that the coated substrates were more bioactive than the uncoated substrates as the cells begin to grow and form a matrix on the coated substrates more easily than on the bare metal. These preliminary results collectively show the potential of use of sol-gel derived calcium phosphate coatings on magnesium based degradable scaffolds to improve their surface bioactivity. 相似文献
57.
Glaucia M. F. Aragao Maria G. Corradini Micha Peleg 《Journal of the American Oil Chemists' Society》2008,85(12):1143-1153
During isothermal lipid oxidation at relatively high temperatures, the peroxide concentration frequently peaks while at relatively
low temperatures it only rises slowly. These are two manifestations of a process where formation and degradation happen simultaneously
on different time scales. A phenomenological mathematical model, comprising a decay factor superimposed on an accumulation
term can describe these scenarios. Each has a characteristic time constant shortened by raising the temperature and a rate
constant that increases with it. The model’s mathematical structure and the magnitude of its coefficients depend on the particular
system. However, regardless of the chosen expressions, if the degradation characteristic time falls within or just beyond
the experiment’s duration, a peak peroxide value will be observed whose height and shape will primarily depend on the other
model’s parameters. If this characteristic time is far outside the time of the experiment , no peak will be recorded. The
model need not be unique and no detailed knowledge of the oxidation mechanisms is required for its formulation. Consequently
it can be derived directly from experimental peroxide value versus time relationships, without the need to monitor the intermediate
reactions by specialized instrumental methods such as DSC. Through the formation term adjustment, the model can also account
for the temperature dependent lag in the rise of the peroxide value and/or the appearance of its peak. 相似文献
58.
Priscila M.A. Alves Rosemary A. CarvalhoIzabel C.F. Moraes Carla G. LucianoAna Mônica Q.B. Bittante Paulo J.A. Sobral 《Food Hydrocolloids》2011
Both gelatin and poly(vinyl alcohol) (PVA) can be cross linked with glutaraldehyde (GLU). In the case of gelatin, the GLU reacts with each ε-NH2 functional group of adjacent lysine residues, while for PVA, the GLU reacts with two adjacent hydroxyl groups, forming acetal bridges. Thus it can be considered possible to cross link adjacent macromolecules of gelatin and PVA using GLU. In this context, the aims of this work were the development of biodegradable films based on blends of gelatin and poly(vinyl alcohol) cross linked with GLU, and the characterization of some of their main physical and functional properties. All the films were produced from film-forming solutions (FFS) containing 2 g macromolecules (PVA + gelatin)/100 g FFS, 25 g glycerol/100 g macromolecules, and 4 g GLU (25% solution)/100 g FFS. The FFS were prepared with two concentrations of PVA (20 or 50 g PVA/100 g macromolecules) and two reaction temperatures: 90 or 55 °C, applied for 30 min. The films were obtained after drying (30 °C/24 h) and conditioning at 25 °C and 58% of relative humidity for 7 days, and were then characterized. The results for the color parameters, mechanical properties, phase transitions and infrared spectra showed that some chemical modifications occurred, principally for the gelatin. However, in general, all the characteristics of the films were either typical of films based on blends of these macromolecules without cross linking, or slightly higher. A greater improvement in the properties of this material was probably not observed due to the crystallinity of the PVA, which has a melting point above 90 °C. The presence of microcrystals in the polymer chain probably reduced macromolecular mobility, hindering the reaction. Thus more research is necessary to produce biodegradable films with improved properties. 相似文献
59.
通过目前已经公开的1989~2006年4月止的中国专利,对生物降解塑料技术专利进行各种指标的分析研究,从而揭示本技术领域中一些有价值的技术经济情报信息,为企业和科研机构的研发、创新活动以及开展知识产权战略提供参考和帮助。 相似文献
60.
Super-hydrophobic surface has been prepared onto biodegradable polymer by a combination of transcribing microscopic structure of a water-repellent leaf and a chemical treatment. An aroid leaf has been chosen for the preparation of the super-hydrophobic surface since the leaf has concavity microscopic structure, which is easy to handle for a material use. The microscopic pattern was transcribed onto poly(ε-caprolactone) (PCL) sheet by using replica method, then it was further treated by soaking in a mixture of acetone/methanol solution. The resultant PCL having the microscopic concavity pattern showed high water contact angle of 148° and also showed antibacterial property for filamentous fungi. 相似文献