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41.
虾保鲜剂的研制 总被引:3,自引:1,他引:2
为延长南美白对虾的保鲜期,本论文以壳聚糖和山梨糖醇等为主要成分与常用防腐保鲜剂进行比较研究.在一定的低温(4℃件下,将市场上新购的活虾,在不同的保鲜剂溶液中浸泡3~5 min,在虾体的体表形成一层保护膜. 在贮藏期间以细菌总数、TVB-N值、pH值和感官评定等作为鲜度指标定期取样测定. 实验结果表明:5%的水溶性壳聚糖、10%的山梨糖醇与4%L-异抗坏血酸钠等复配而成的天然保鲜剂用于南美白对虾的保鲜效果显著. 与空白对照组相比,可延缓细菌总数增长2~3d,5d内抑制TVB-N值在30. 0×10-2mg/g以下,维持了较低的pH值.本论文将对提高虾的品质,促进我国水产加工业的健康发展,具有重大的意义. 相似文献
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L. L. Barbosa Guilherme Antonio Finazzi P. C. Tulio I. A. Carlos 《Journal of Applied Electrochemistry》2008,38(1):115-125
The chronopotentiometric technique was used to analyze the electrodeposition of Fe–Zn film on a Pt electrode. Three different
Fe3+/Zn2+ molar ratios, Fe26.8 wt.%–Zn73.2 wt.%, Fe46 wt.%–Zn54 wt.% and Fe66.6 wt.%–Zn33.4 wt.%, were used in a solution containing
sorbitol as the Fe3+-complexing agent, with a total concentration of the two cations of 0.20 M. Coloration of Fe–Zn films were light gray, dull
dark gray and bright graphite, depending on the Fe3+/Zn2+ ratios in the deposition bath. The highest stripping to deposition charge density ratio was 47.5%, at 15 mA cm−2 in the Fe26.8 wt.%–Zn73.2 wt.% bath. Energy dispersive spectroscopy indicated that the codeposition type of Fe and Zn in
the Fe26.8 wt.%–Zn73.2 wt.% and Fe46 wt.%–Zn54 wt.% baths was normal at all jd tested, while in the Fe66.6 wt.%–Zn33.4 wt.% bath there was a transitional current density from normal to equilibrium codeposition
at 50 mA cm−2. Scanning electron microscopy showed that Fe–Zn films of high quality were obtained from the Fe66.6 wt.%–Zn33.4 wt.% and
Fe26.8 wt.%–Zn73.2 wt.% baths, since the films were smooth. X-ray analysis of the Zn–Fe films obtained at 15, 25 and 50 mA cm−2, in the Fe26.8 wt.%–Zn73.2 wt.%, Fe46 wt.%–Zn54 wt.% and Fe66.6 wt.%–Zn33.4 wt.% plating baths, suggested the occurrence,
in general, of a mixture of Fe11Zn40, Fe4Zn9, βFe, αFe, Fe2O3, Zn and PtZn alloys in the deposit. 相似文献
45.
Starch-gelatin edible films: Water vapor permeability and mechanical properties as affected by plasticizers 总被引:5,自引:0,他引:5
A.A. Al-HassanM.H. Norziah 《Food Hydrocolloids》2012,26(1):108-117
Physical and mechanical properties of edible films based on blends of sago starch and fish gelatin plasticized with glycerol or sorbitol (25%, w/w) were investigated. Film forming solutions of different ratios of sago starch to fish gelatin (1:0, 2:1, 3:1, 4:1, and 5:1) were used and cast at room temperature. Amylose content of sago starch was between 32 and 34% and the protein content of the fish gelatin was found to be 81.3%. The findings of this study showed that the addition of fish gelatin in starch solutions has a significant effect (p < 0.05), resulting in films with lower tensile strength (TS) and higher water vapor permeability (WVP). On the other hand, increasing protein content (from 10.9% to 21.6%) in film samples plasticized with sorbitol showed significantly lower (p < 0.05) TS but no trend was observed in % elongation-at-break (EAB) and no differences in WVP. However, TS decreased with higher protein content in the samples when either plasticizers were used in general, but no significance differences was observed among the samples (p < 0.05) with glycerol with exception to film with high protein content (21.6%) only and no trend was observed in % EAB among samples as well. Significant difference (p < 0.05) was observed in TS and viscosity between different formulations with sorbitol. The morphology study of the sago starch/fish gelatin films showed smoother surfaces with decreasing protein in the samples with either plasticizer. DSC scans showed that plasticizers and protein content incorporated with sago starch films reduced the glass transition temperature (Tg) and melting temperature (Tm) and the melting enthalpy (ΔHm). In this study, observation of a single Tg is an indication of the compatibility of the sago starch and fish gelatin polymers to form films at the concentration levels used. 相似文献
46.
With regard to 45 pomegranate fruits from different regions and several domestic varieties, fruit weight was found to be 137.1–738.2 g, peel share 34.4–73.1%, aril share 26.9–65.6% and fruit juice yield 19.2–48.0%. Brix degree of pomegranate juice samples obtained from the aforementioned fruits changed from 12.2 to 17.8 and was lower than 14.0 in approximately 18% of the samples. Titratable acidity of pomegranate juice samples varied between 2.4 and 30 g/L and the formol number varied between 4.0 and 20.0. The sorbitol/xylitol content ranged between 16 and 423 mg/L, mostly lying between 51 and 200 mg/L with a frequency of 64%. The share of samples containing sorbitol/xylitol higher than 250 g/L is 7%. 相似文献
47.
Dr. Reinhard Geyer Dr. Peter Kraak Dr. Axel Pachulski Dr. Rainer Schödel 《化学,工程师,技术》2012,84(4):513-516
Nickel catalysts supported on ZrO2, TiO2 and ZrO2/TiO2 mixtures performed more active, selective and stable than Ni/SiO2 catalysts in the hydrogenation of glucose to sorbitol. This was shown by catalytic testing as well as by determination of Ni crystallite size before and after the test. The reason for the better performance was assumed to be metal‐support interaction in the Ni/ZrO2, Ni/TiO2 and Ni/ZrO2/TiO2 catalysts. 相似文献
48.
In this work, we compare the effects of sorbitol derivatives (1,3:2,4-dibenzylidene sorbitol (DBS), 1,3:2,4-di(p-methylbenzylidene) sorbitol (MDBS) and 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol (DMDBS)) on the performances of poly(3-octyl thiophene)/[6,6]-phenyl C61-butyric acid methyl ester (P3OT/PCBM) bulk heterojunction (BHJ) organic photovoltaic (OPV) devices and explore the mechanism. Differential scanning calorimetry (DSC) and atomic force microscopy (AFM) measurements indicate that DBS, MDBS and DMDBS are nucleating agents of P3OT. DMDBS has the strongest molecular polarizability and exhibits the best propensity for self-assembly in 1,2-dichlorobenzene (ODCB). The strong π-π stacking of aromatic benzylidene group and the high density of the fibrillary aggregates supply more nucleation surfaces for P3OT, leading DMDBS has the highest nucleation efficiency (NE). Sorbitol derivatives accelerate the crystallization rate (G) of P3OT with the order as GP3OT/DMDBS > GP3OT/MDBS > GP3OT/DBS > GP3OT. The acceleration of the crystallization increases the number of tie molecules, causing the improvement of the connectivity between ordered regions, resulting dramatically increasing the carrier transport of P3OT. GP3OT/DMDBS is highest, the connectivity between ordered regions is best in P3OT with DMDBS. UV–vis measurement indicates that the intra-chain order of P3OT reduces with the addition of sorbitol derivative, and the intra-chain order of P3OT with DMDBS is lowest. The P3OT/PCBM/sorbitol derivative BHJ OPV devices were fabricated and show that the short circuit current JSC P3OT/DMDBS > JSC P3OT/MDBS > JSC P3OT/DBS > JSC P3OT. It hints that the connectivity of tie molecules plays a significant role in defining semiconducting polymer transport characteristics, and is perhaps more important than molecular level interactions (inter- and intra-chain order) for efficient macroscopic charge carrier transport. Finally, it shows that adding sorbitol derivatives can improve the power conversion efficiency (PCE) of P3OT/PCBM BHJ OPV device, the best PCE as 1.77% is obtained in the P3OT/PCBM/DMDBS device. 相似文献
49.
以籼米为主要原料,添加单甘酯、复合磷酸盐、TG酶(谷氨酰胺转氨酶)和山梨醇,制作大米凝胶,研究添加物对大米凝胶的热特性、流变特性、晶体结构、微观结构的影响,初步探究添加物对大米凝胶稳定性的作用机理。结果表明,添加TG酶、复合磷酸盐、单甘酯能显著提高大米凝胶的糊化峰值温度,而添加山梨醇则降低大米凝胶的糊化峰值温度。添加TG酶、山梨醇、单甘酯能显著提高大米凝胶的糊化热焓,而添加复合磷酸盐降低了大米凝胶的糊化热焓。四种添加物均能提高大米凝胶的弹性模量(G')上升的起始温度(T_(oG'))和G'峰值对应的温度(T_(G'max));添加山梨醇的大米凝胶,其弹性模量峰值(G'_(max))和黏性模量峰值(G″_(max))增大,而添加TG酶、复合磷酸盐、单甘酯的大米凝胶,其G'_(max)和G″_(max)降低。四种添加物均能降低大米凝胶G'值的变化速率和结晶程度,抑制凝胶的老化,降低凝胶内部孔洞数量和凝胶表面粗糙度。 相似文献
50.