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1.
2.
The glycerol region geometry of modeled saturated monoacid triglycerides was altered by bond rotations and minor angle distortions
to convert theoretical α-forms into bent β′- and β-forms. Direct α to β conversion involves lateral disruption of fatty chain
packing to generate side-chain character typical of the β-form. Such disruption, which could contribute to fat bloom, allows
additional molecular movement and shifts in molecular mechanics energy (MME) that may approximate thermal changes observed
by differential scanning calorimetry during α to β transformations. Energy calculations at 100 points throughout each transformation
identified plausible conversion routes. A two-stage conversion, α to either of two stereospecific β′-forms bent at glycerol
followed by subsequent conversion to β, showed less chain movement and more favorable MME than direct α to β conversion. The
preferred path, based on energy profiles of each conversion, involves a β′-D form and rotation of carbonyl to α-carbon bonds
in chain #2 and a side chain (chain #3). 相似文献
3.
Dorota Johansson Björn Bergenståhl 《Journal of the American Oil Chemists' Society》1992,69(8):728-733
The influence of water on the interactions between fat and sugar crystals dispersed in triglyceride (vegetable) oils was qualitatively
estimated from sedimentation and rheological experiments. The experiments were performed both with and without food emulsifiers
(monoglycerides and lecithins) present in the oil. The effects of minor natural oil components (nontriglycerides) on the interactions
and on emulsifier adsorption to the crystals were examined by comparing a commercial refined oil and a chromatographically
purified oil. The results show that water generally increases the adhesion between fat and sugar crystals in oils and also
increases the surface activity of the oil-soluble food emulsifiers. Minor oil components give a small increase in the adhesion
between fat and sugar crystals in oils, but do not influence the adsorption of food emulsifiers in any systematic way. 相似文献
4.
Guan-Chiun?Lee Dong-Lin?Wang Yi-Fang?Ho Jei-Fu?ShawEmail author 《Journal of the American Oil Chemists' Society》2004,81(6):533-536
Lipase from Pseudomonas fluorescens efficiently catalyzed the alcoholysis of various TG in dry alcohols. For TG with short-chain FA, more MG were accumulated.
The yields of MG were affected by the alcohols used. The maximum yields of MG were as follows: 85% for monoacetin in n-butanol, 96% for monobutyrin in ethanol or n-butanol, 50% for monocaprylin in n-butanol, 48% for monolaurin in isopropanol, and 45% for monopalmitin in isopropanol. The MG produced were judged to be 2-MG
by TLC analysis. The presence of organic cosolvent affected the reaction rate of the lipase-catalyzed alcoholysis of TG. For
the alcoholysis of various TG in ethanol and cosolvent (1∶1, vol/vol), the rates had the following orders: (i) for tributyrin,
hexane > toluene > acetone > ethyl acetate > chloroform > acetonitrile > pyridine; (ii) for tricaprylin, hexane > acetone
> toluene > acetonitrile > ethyl acetate > pyridine > chloroform; and (iii) for trialurin, hexane > acetonitrile=acetone >
ethyl acetate > pyridine=chloroform > toluene. 相似文献
5.
Yuen May Choo Ah Ngan Ma Hawari Yahaya Y. Yamauchi M. Bounoshita M. Saito 《Journal of the American Oil Chemists' Society》1996,73(4):523-525
Successful separation of triglycerides, diglycerides, free fatty acids, carotenes, tocopherol, and tocotrienols from crude
palm oil has been achieved by supercritical fluid chromatography (SFC) with a combination of a C18 and a silica gel column.
The separation was carried out by the programmed extraction elution method. Free fatty acids were separated into five components
by gas-liquid chromatography; tocopherol and tocotrienols were also separated into four components by SFC analysis, and the
pure fractionated carotenes were obtained by preparative SFC. Thus, by using supercritical fluid chromatography, crude palm
oil components can be separated and fractionated, based on differences in their functional groups. 相似文献
6.
7.
研究了在超临界CO2状态下酶法酯化合成长短链脂肪酸三酰甘油的工艺条件,选用脂肪酶Lipozyme RM IM,以酯化率为参考指标,通过单因素试验考察反应压力、反应温度、反应时间、体系水分添加量、酶用量和底物物质的量比对酯化率的影响,再通过响应面对工艺条件进行优化,结果:反应压力11 MPa、反应温度56℃、反应时间15 h、体系水分添加量2.5%、酶用量4%、底物物质的量比3∶1。在此最佳工艺条件下进行酯交换试验,测得产品的酯化率为65.3%,且此法制得的三酰甘油热量值较普通葵花油降低了大约50%。 相似文献
8.
以氢化大豆油和反刍动物脂质为研究对象,采用Folch法提取油脂,氨丙基硅胶固相萃取小柱分离出油脂中的甘油三酯和磷脂,利用Sn-1,3专一性脂肪酶作用甘油三酯得到Sn-2甘油一酯和游离脂肪酸,磷脂酶A2作用磷脂得到游离脂肪酸和Sn-1溶血磷脂,并通过气相色谱分析2种不同来源油脂反式脂肪酸在甘油三酯和磷脂中的含量和位置分布情况。结果表明,反式脂肪酸占氢化大豆油甘油三酯总脂肪酸的41.466%,占反刍动物油脂甘油三酯总脂肪酸的2.451%~3.179%。反式脂肪酸在氢化大豆油甘油三酯中主要分布在Sn-2位,而在反刍动物油脂甘油三酯中主要分布在Sn-1,3位,在反刍动物油脂磷脂中则易分布在Sn-1上。不同来源的反式脂肪酸的膳食摄入量及其在甘油三酯中的位置分布不同,可能是导致不同来源反式脂肪酸对人体健康影响差异的原因。 相似文献
9.
在复合磁性载体ZrO_2/Fe_3O_4上负载碱源KF,制备出KF/ZrO_2/Fe_3O_4磁性固体碱催化剂,通过扫描透射电镜、比表面测试、碱强度、碱量测定等方法对催化剂的形貌结构与碱性进行表征,并将其应用于聚甘油的催化合成中,评价其催化性能。结果显示,该磁性固体碱催化剂表面负载有一定量的KF碱性活性中心,碱强度pH在11.1~15.0之间,总碱量为0.2mmol/g,为固体强碱类催化剂。在聚甘油合成中,反应条件温和,产品聚合度适中,色泽较浅,产物与催化剂易分离,表现出明显的催化活性,具有较高的应用价值与经济价值。 相似文献
10.
The demulsification of oil-in-water (O/W) emulsions under freezing conditions is connected to fat crystallization in the oil
droplet. Therefore, demulsification can be prevented by the use of oil with a low melting point, and also by lowering the
O/W ratio. However, an oil with a low melting point, such as sunflower, is rather expensive, and the O/W ratio has a significant
effect on the texture of emulsions. We searched for an oil that is suitable for the production of a freeze-stable emulsion
and found that soybean oil has unique characteristics. Normally, emulsions are more unstable at lower temperatures; soybean
oil emulsion is unstable at −10°C and stable at −20°C. This unique characteristic results from the following two reasons.
First, the solid fat content of soybean oil is almost the same at −10 and −20°C. Second, small crystals form a larger network
over a period of time, and the higher temperature promotes faster restructuring. This structure formation was microscopically
observed with the use of a thermostated stage. Structure formation was suppressed with the addition of a crystal structure
modifier, polyglycerol fatty acid full ester, which also suppressed coalescence. 相似文献