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目的提供一种以化学接枝法替代传统物理吸附法的理论思路,改善机制砂石粉在水泥中的和易性。方法先将机制砂石粉与硅烷偶联剂γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(MPS)进行羟基反应,使其表面带有C=C化学官能团,再与丙烯酸(AA)、2-甲基丙烯酸聚乙二醇单甲醚酯(MPEG)共聚。采用傅里叶变换红外光谱(FT-IR)、场发射扫描电镜、热重曲线、X射线衍射等分析手段表征机制砂石粉的改性效果和表面结构。将合成的复合材料以不同的比例掺杂于水泥中,通过净浆实验研究合成材料与水泥的流动适应性和流动保持性。结果生成的高分子化合物以化学键的方式链接在机制砂石粉表面。与未修饰的机制砂石粉相比,修饰后的机制砂石粉的可流动性及流动保持性有较大改善。结论经高分子化合物改性后,机制砂石粉在水泥中的流动适应性和流动保持性有显著提高。该思路合成的新型材料对水泥基复合材料的理论研究有一定的现实意义。 相似文献
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选择氧化锌(Zn O)、铝掺杂氧化锌(AZO)、氧化锡锑(ATO)以及ATO包覆硫酸钡(Ba SO4)4种纳米粉体抗静电剂球磨分散得到其水相悬浮液,利用喷雾共混的方法制备改性聚丙烯腈(PAN)纺丝原液,进行湿法纺丝,研究了表面活性剂种类、研磨工艺对纳米粉体在水相中沉降性的影响,以及改性PAN纤维的抗静电性能。结果表明:采用自制的非离子/阴离子表面活性剂复配物(FCY)作为分散剂,FCY质量分数(相对于纳米粉体)为2%,研磨时间3 h,纳米粉体的水相分散效果好,分散工艺对4种纳米粉体均有很好的适用性;ATO改性PAN纤维具有较好的抗静电效果,当添加ATO质量分数为2.0%时,PAN纤维的体积比电阻为3.1×109Ω·cm,具有耐久性,可以满足抗静电织物对原料的要求。 相似文献
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《International Journal of Hydrogen Energy》2020,45(56):32145-32156
Agglomeration of CoB catalysts is a severe problem in hydrogen generation from NaBH4 hydrolysis. Herein, highly dispersed carbon nanofiber immobilized CoB catalysts (CoB/CN) were synthesized by a combined prereduction and carbonization method, which is used in hydrogen generation from NaBH4 hydrolysis. Morphological evolution of carbon nanofibers, phase structure and elemental distribution of CoB/CN catalysts are explored by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Compared to Co/carbon nanofiber catalysts (Co/CN) without prereduction, CoB/CN catalysts can afford higher CoB dispersity and specific surface area because the migration rate of cobalt species during carbonization is effectively retarded by prereduction. Hence the agglomeration of magnetic CoB nanoparticles can be effectively inhibited. The hydrogen generation experiment shows that CoB/CN catalysts process higher catalytic activity and lower activation energy than Co/CN. 相似文献
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采用荧光显微镜和沥青基本性能测试分析的方法,研究了糠醛抽出油对SBS改性沥青性能的影响。结果表明,糠醛抽出油的掺入能显著改善SBS在沥青中的分散性,使得SBS溶胀得更为充分,提高了改性沥青的抗老化性能和高温存储稳定性。随着糠醛抽出油掺量的增加,针入度逐渐升高,软化点和延度先升高后下降。 相似文献
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Dispersity in polymer science (IUPAC Recommendation 2009) 总被引:1,自引:0,他引:1
R. F. T. Stepto 《Polymer International》2010,59(1):23-24
This recommendation defines just three terms, viz., 1. molar‐mass dispersity, relative‐molecular‐mass dispersity, or molecular‐weight dispersity, 2. degree‐of‐polymerization dispersity, and 3. dispersity. “Dispersity” is a new word, coined to replace the misleading, but widely used term “polydispersity index” for M?w/M?n and X?w/X?n. The document, although brief, also has a broader significance in that it seeks to put the terminology describing dispersions of distributions of properties of polymeric (and non‐polymeric) materials on an unambiguous and justifiable footing. Copyright © 2009 Society of Chemical Industry 相似文献
8.
Yong S. Chung Sung I. Kang Oh W. Kwon Se G. Lee Yong R. Lee Byung G. Min Sung S. Han Seok K. Noh Won S. Lyoo 《应用聚合物科学杂志》2007,104(5):3240-3244
Biocompatible hydroxyapatite (HA)/poly(vinyl alcohol) (PVA) composites and their transparent films were prepared by the coprecipitation and solvent casting method. The formation of HA in PVA composite powder was confirmed by the characteristic phosphate bands at 1100–1032 and 565 cm?1 at FT‐IR spectra, and the weight ratio of HA to PVA was 50/50 examined by TGA. The crystal melting temperature of HA/PVA decreased compared with that of pure PVA. HA/PVA (50/50) composite powder and pure PVA were dissolved in dimethyl sulfoxide to obtain a film with HA/PVA weight ratio of 10/90. To improve HA particles' dispersity, which is one of the major factors affecting the mechanical properties of composite materials, various contents of citric acid were used for the preparation of HA/PVA films. At a citric acid concentration of 5 wt %, HA/PVA film with good dispersity of HA particles was obtained. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
9.
The interaction of nitrous oxide with ruthenium surfaces was studied in order to develop a fast and reliable method for the determination of the metallic surface area and dispersity of ruthenium catalysts as alternative to the established chemisorption methods using hydrogen, carbon monoxide or oxygen as probe molecule. Studies of the temperature dependence of the reactive or dissociative chemisorption of nitrous oxide using pulse technique showed that an oxygen monolayer of almost constant stoichiometry is formed in a narrow temperature range around 403 K. However, so-called ‘rest nitrogen peaks' were observed after saturation of an O-monolayer revealing a small additional nitrous oxide conversion which could be attributed to formation of subsurface oxygen by means of back-titration of the oxygen totally uptaken. This additional nitrous oxide consumption can be minimised by an adjustment of both the N2O-sampling loop volume and the catalyst sample weight in order to obtain an oxygen monolayer saturation by few pulses, and moreover, it can be considered as a correction for the calculation of the oxygen monolayer. A specific nitrous oxide consumption of 13.5 μmol/m2Ru has been determined on ruthenium black by means of alternating measurements of the nitrogen physisorption and N2O-pulse chemisorption. The reliability of the new method for characterisation of the dispersity or surface area of supported ruthenium was proved with ruthenium highly dispersed on γ-alumina. 相似文献
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