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1.
近红外光谱法检测聚醚多元醇伯羟基与仲羟基的相对含量   总被引:4,自引:1,他引:3  
文章利用近红外光谱法,采用多元线性回归检测了聚醚多元醇的伯羟基与仲羟基的相对含量,得到了较好的预测结果,对工业在线检测具有重要的参考价值.  相似文献
2.
采用FTIR技术跟踪研究了由乙二醇和环氧氯丙烷以及烯丙基缩水甘油醚共聚而成的不饱和氯代聚醚多元醇,与亚磷酸三甲酯发生酯交换反应和酯交换聚合反应以及Arbuzov重排反应过程,合成反应型聚醚多元醇亚磷酸酯阻燃剂的方法。实验考察了物质量配比、反应温度、投料方式等对上述反应进程的影响。分析结果表明反应温度是决定上述反应进程的关键因素,同时适当条件下合成的反应产物,可以用作一种光固化的兼有抗老化和增塑功能新型有机磷酸酯阻燃剂。  相似文献
3.
通过催化加氢来降低柴油中芳烃含量是提高油 品质量的一个重要过程.贵金属催化剂,如Pd或 Pt,具有非常高的反应活性,但易被原料油中的含硫 有机化合物毒化[1].因此,提高贵金属催化剂的耐 硫性能是一个重要的课题.已有的研究结果表明,贵 金属催化剂硫中毒的主要原因是硫在金属中心上产 生强化学吸附,因此,调节金属中心和硫之间的电子 相互作用可以改进催化剂的耐硫性能[2,3]. 催化生长的碳纳米纤维(CNF)是一种新型的碳 材料,其石墨层沿轴线方向闭合的特殊结构使它具 …  相似文献
4.
Microwave-assisted polyol process was developed for the synthesis of magnetite nanoparticles with precisely controlled size, high crystallinity and high water solubility. The process is simple, time-saving and low energy-consuming due to the advantages of polyols and microwave irradiation combined. The crystal phases of the nanoparticles were determined by transmission electron microscopy, X-ray powder diffraction and Raman spectrum. The coating materials of the nanoparticles were analyzed by Fourier transformed infrared spectroscopy and thermal gravimetric analysis. Precise size tuning enables an easier way to adjust the relaxation properties of the magnetite nanoparticles. The colloid nanoparticles with high longitudinal relaxivity (r1) and low ratio of transverse relaxivity (r2) to r1 have a potential application in magnetic resonance angiography.  相似文献
5.
Small crystallites of a metastable phase Co0.5Pt0.5 are precipitated by heating a rheological liquid precursor of cobalt–hydrazine complex and platinum chloride H2PtCl6·xH2O in polymer molecules of poly(vinylpyrrolidone) (PVP) in ethylene glycol. The hydrazine co-reduces nascent atoms from the Co2+ and Pt4+ that recombine and grow as Co0.5Pt0.5. The PVP molecules cap a growing Co0.5Pt0.5 as it achieves a critical size so that it stops growing further in given conditions. X-ray diffraction pattern of a recovered powder reveals a crystalline Co0.5Pt0.5 phase (average crystallite size D∼8 nm) of a well-known Fm3m-fcc crystal structure with the lattice parameter a=0.3916 nm (density ρ=14.09 g/cm3). A more ordered L10 phase (ρ=15.91 g/cm3) transforms (D≥25 nm) upon annealing the powder at temperature lesser than 700 °C (in vacuum). At room temperature, the virgin crystallites bear only a small saturation magnetization Ms=5.54 emu/g (D=8 nm) of a soft magnet and it hardly grows on bigger sizes (D≤31 nm) in a canted ferromagnetic structure. A rectangular hysteresis loop is markedly expanded on an optimally annealed L10 phase at 800 °C for 60 min, showing a surface modified coercivity Hc=7.781 kOe with remnant ratio Mr/Ms=0.5564, and Ms=39.75 emu/g. Crystallites self-assembled in an acicular shape tailor large Hc from ideal single domains and high magnetocrystalline anisotropy of a hard magnet L10 phase.  相似文献
6.
The influence of PVP on the magnetic properties of NiSn nanoparticles prepared by polyol method has been studied. NiSn nanoparticles exhibit superparamagnetic behavior although there is a ferromagnetic contribution due to particles agglomerated below the blocking temperature. The particle size is controlled by the addiction of PVP in varying amounts. The addition of PVP also favours the particles isolation, narrow the particle size distribution and decrease the interparticle interaction strength increasing the superparamagnetic contribution.  相似文献
7.
A polyol synthesis of silver nanoparticles in the presence of ultrasonic irradiation was compared with other configurations (at ambient temperature, 120 °C, and 120 °C with injected solutions) in the absence of ultrasonic irradiation in order to obtain systematic results for morphology and size distribution. For applying ultrasonic irradiation, rather fine and uniform spherical silver particles (21 ± 3.7 nm) were obtained in a simple (at ambient temperature without mechanical stirring) and fast (within 4 min, 3.61 × 10−3 mol min−1) manner than other cases (at ambient temperature (for 8 h, 0.03 × 10−3 mol min−1): 86 ± 16.8 nm, 120 °C (for 12 min, 1.16 × 10−3 mol min−1): 64 ± 14.9 nm, and 120 °C with injected solutions (during 12 min): 35 ± 6.8 nm; all other cases contained anisotropic shaped particles). Even though the temperature of polyol reaction reached only at 80 °C (<120 °C) in the presence of ultrasonic irradiation, a uniform mixing (i.e. enhanced collision between silver particle and surrounding components) by ultrasonic irradiation might induce a better formation kinetics and morphological uniformity.  相似文献
8.
研究了利用乙二醇、甘油、木糖醇、山梨醇、葡萄糖多元醇共浸渍方法促进Ni负载在MCM-41载体上的萘加氢活性.和传统的浸渍方法比较,只要在硝酸盐的水溶液中添加适合量的多元醇即可以提高金属活性中心和载体表面的相互作用,导致5 nm以下超细NiO粒子的形成,以及高分散的催化活性中心和异常高的催化活性;零价Ni的纳米粒子从36.1 nm减少到5 nm以下,同时萘的加氢活性取决于零价Ni纳米粒子的大小.利用多元醇共浸渍制备的负载型催化剂表现出优异的催化活性,即使在55 oC的低温环境中亦表现出100%的萘转化率.  相似文献
9.
We report our recent results in synthesis and characterization of cobalt carbide (Co3C and Co2C) nanoparticles and nanowires. The synthesis methods were based on a simple one-pot tetraethylene glycol reduction process. By changing the synthesis parameters, the nanocrystal morphology can be adjusted from nanoparticles with different size to nanowires. The magnetic properties of the nanostructure and their correlation to the crystalline structures and the nanoscale morphology have been investigated theoretically and experimentally. It is revealed that the properties are related to both the crystal structures and the morphology.  相似文献
10.
Self-assembled Sm-Co nanoparticles in the form of spherical aggregates (referred as nanospheres) with diameter ranging from 50 to 180 nm were achieved by means of polyol technique. The size distribution of the Sm-Co nanospheres can be regulated close to ∼100 nm by controlling the molar ratio of Sm:Co precursor. The spherical aggregates exhibited Sm2Co7 phase as a major constituent; while the aggregates obtained at higher Co concentration showed co-existence of Co-phase with Sm2Co7 phase. Upon annealing, the biphasic nature of nanospheres (Sm2Co7/Co) transformed into Sm2Co17 structure. By varying the Sm:Co precursor ratio from 1:5 to 1:9, the coercivity (Hc) and magnetization (Ms) values of the as-synthesized nanospheres can be tuned from 336 to 140 Oe and from 63.7 to 108 emu/g, respectively, and these values significantly improved after annealing. Maximum values of Hc (1050 Oe) at the Sm:Co molar ratio of 1:5 and Ms of 184.6 emu/g at the Sm:Co molar ratio of 1:9 were achieved in the annealed samples.  相似文献
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