全文获取类型
收费全文 | 260篇 |
免费 | 38篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 1篇 |
综合类 | 4篇 |
化学工业 | 122篇 |
金属工艺 | 5篇 |
机械仪表 | 3篇 |
能源动力 | 1篇 |
轻工业 | 162篇 |
石油天然气 | 1篇 |
无线电 | 1篇 |
一般工业技术 | 4篇 |
出版年
2024年 | 4篇 |
2023年 | 8篇 |
2022年 | 10篇 |
2021年 | 15篇 |
2020年 | 14篇 |
2019年 | 10篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 13篇 |
2013年 | 12篇 |
2012年 | 12篇 |
2011年 | 17篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 6篇 |
2007年 | 2篇 |
2006年 | 11篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 8篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1985年 | 1篇 |
排序方式: 共有304条查询结果,搜索用时 22 毫秒
91.
A. Witthayapanyanon E. J. Acosta J. H. Harwell D. A. Sabatini 《Journal of surfactants and detergents》2006,9(4):331-339
Inspired by the concept of lipophilic and hydrophilic linkers, extended surfactants have been proposed as highly desirable
candidates for the formulation of microemulsions with high solubilization capacity and ultralow interfacial tension (IFT),
especially for triglyceride oils. The defining characteristic of an extended surfactant is the presence of one or more intermediate-polarity
groups between the hydrophilic head and the hydrophobic tail. Currently only limited information exists on extended surfactants;
such knowledge is especially relevant for cleaning and separation applications where the cost of the surfactant and environmental
regulations prohibit the use of concentrated surfactant solutions. In this work, we examine surfactant formulations for a
wide range of oils using dilute solutions of the extended surfactant classes sodium alkyl polypropyleneoxide sulfate (R-(PO)
x
−SO4Na), and sodium alkyl polypropyleneoxide-polyethyleneoxide sulfate (R-(PO)
y
-(EO)
z
−SO4Na). The IFT of these systems was measured as a function of electrolyte and surfactant concentration for polar and nonpolar
oils. The results show that these extended surfactant systems have low critical micelle concentrations (CMC) and critical
microemulsion concentrations (CμC) compared with other surfactants. We also found that the unique structure of these extended
surfactants allows them to achieve ultralow IFT with a wide range of oils, including highly hydrophobic oils (e.g., hexadecane),
triolein, and vegetable oils, using only ppm levels of these extended surfactants. It was also found that the introduction
of additional PO and EO groups in the extended surfactant yielded lower IFT and lower optimum salinity, both of which are
desirable in most formulations. Based on the optimum formulation conditions, it was found that the triolein sample used in
these experiments behaved as a very polar oil, and all other vegetable oils displayed very hydrophobic behavior. This unexpected
triolein behavior is suspected to be due to uncharacterized impurities in the triolein sample, and will be further evaluated
in future research. 相似文献
92.
Synthesis of polyunsaturated fatty acid-enriched triglycerides by lipase-catalyzed esterification 总被引:2,自引:0,他引:2
L. Esteban Cerdán A. Robles Medina A. Giménez Giménez M. J. Ibáñez González E. Molina Grima 《Journal of the American Oil Chemists' Society》1998,75(10):1329-1337
This paper reports on the synthesis of triglycerides by enzymatic esterification of polyunsaturated fatty acids (PUFA) with
glycerol. A PUFA concentrate obtained from cod liver oil was used to optimize the reaction to favor triglyceride synthesis
with lipases. The type and amount of lipase and organic solvent, glycerol content, temperature, water content, and amount
and time of addition of molecular sieves were studied. The optimal reaction mixture and conditions were: 9 mL hexane, 60°C,
0.5% (vol/vol) water, 1 g molecular sieves added after 24 h of reaction, glycerol/fatty acid molar ratio 1:3 and 100 mg of
Novozym 435 (Novo Nordisk A/S) lipase. Under these conditions, an enriched triglyceride yiedl of 84.7% containing 27.4% eicosapentaenoic
acid and 45.1% docosahexaenoic acid was obtained from a cod liver oil PUFA concentrate. 相似文献
93.
T. Haryati Y. B. Che Man H. M. Ghazali B. A. Asbi L. Buana 《Journal of the American Oil Chemists' Society》1998,75(7):789-792
The triglyceride (TG) composition of palm oil is normally determined by high-performance liquid chromatography (HPLC). The
HPLC chromatograms indicated a good separation of most of the TG components in the oil. The TG can be classified based on
either the TG groups, i.e., triunsaturated, monosaturated, disaturated, or trisaturated, or the number of double bonds, i.e.,
zero, one, two, three, or four double bonds. The more unsaturated the fatty acid, the greater the iodine value (IV). Therefore,
it is hypothesized that the IV of an oil can be determined based upon the TG composition of the oil. Based on the TG groups,
stepwise regression analysis showed that the areas of the disaturated, trisaturated, and triunsaturated TG peaks could predict
the IV with a coefficient of determination (R
2) of 0.990. The regression based on the number of double bonds yielded a good regression equation with R
2=0.992. The important variables were the peak area of the fatty acids that contained zero, one, two, and three double bonds.
This study concludes that the TG composition can be used to predict the IV of palm oil. The best prediction model is obtained
by using the number of double bonds in the TG as the independent variable. 相似文献
94.
Structure of Inclusion Complexes of Cyclodextrins with Triglyceride at Vegetable Oil/Water Interface
K.AZUKO SHIMADA K.IMIKO KAWANO J.UNKO ISHII T.AKASHI NAKAMURA 《Journal of food science》1992,57(3):655-656
The interfacial tension of vegetable oil (soybean oil or coconut oil)/ water interface decreased with the increase of cyclodextrin (CD) concentration. The interfacial excess and interfacial area were calculated from the Gibbs’ adsorption equation. The average number of CD molecules including a fatty acid residue of soybean oil at the interface was estimated at 2.4 for each of α-CD and β-CD. The average number of CD molecules complexed with a fatty acid residue of coconut oil was 1.8 for α-CD and 1.7 for β-CD. These results suggested that the CD molecules formed the inclusion complex with the triglyceride according to the chain length of fatty acid residue at the interface. 相似文献
95.
Nestor?U.?SorianoJr. Veronica?P.?Migo Masatoshi?MatsumuraEmail author 《Journal of the American Oil Chemists' Society》2003,80(10):997-1001
Consumption of ozone by unsaturated FA moieties of sunflower oil (SFO) was monitored by 1H NMR and FTIR spectroscopy. Degradation of linoleate was found to be 1.5 and 1.8 times higher than oleate when SFO was ozonized
in the absence and presence of water, respectively. Products of ozonation in both cases include aldehydes and ozonides with
1,2,4-trioxolane ring. Hydroxyl-containing compounds, which could be carboxylic acids and/or hydroperoxides, were also detected
in samples ozonized in the presence of water. The extent of ozonation had very little effect on the aldehyde/ozonide ratio
obtained from NMR spectra, especially in the ozonation of neast SFO. The aldehyde/ozonide ratios obtained regardless of the
extent of ozonation were 10.5:89.5 and 46.6:53.4 for SFO ozonized in the absence and presence of water, respectively. 相似文献
96.
Shrikant N. Khot John J. Lascala Erde Can Shantaram S. Morye George I. Williams Giuseppe R. Palmese Selim H. Kusefoglu Richard P. Wool 《应用聚合物科学杂志》2001,82(3):703-723
Triglyceride oils derived from plants have been used to synthesize several different monomers for use in structural applications. These monomers have been found to form polymers with a wide range of physical properties. They exhibit tensile moduli in the 1–2 GPa range and glass transition temperatures in the range 70–120 °C, depending on the particular monomer and the resin composition. Composite materials were manufactured utilizing these resins and produced a variety of durable and strong materials. At low glass fiber content (35 wt %), composites produced from acrylated epoxidized soybean oil by resin transfer molding displayed a tensile modulus of 5.2 GPa, a flexural modulus of 9 GPa, a tensile strength of 129 MPa, and flexural strength of 206 MPa. At higher fiber contents (50 wt %) composites produced from acrylated epoxidized soybean oil displayed tensile and compression moduli of 24.8 GPa each, and tensile and compressive strengths of 463.2 and 302.6 MPa, respectively. In addition to glass fibers, natural fibers such as flax and hemp were used. Hemp composites of 20% fiber content displayed a tensile strength of 35 MPa and a tensile modulus of 4.4 GPa. The flexural modulus was ∼2.6 GPa and the flexural strength was in the range 35.7–51.3 MPa, depending on the test conditions. The flax composite materials had tensile and flexural strengths in the ranges 20–30 and 45–65 MPa, respectively. The properties exhibited by both the natural- and synthetic fiber-reinforced composites can be combined through the production of “hybrid” composites. These materials combine the low cost of natural fibers with the high performance of synthetic fibers. Their properties lie between those displayed by the all-glass and all-natural composites. Characterization of the polymer properties also presents opportunities for improvement through genetic engineering technology. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 703–723, 2001 相似文献
97.
血浆低密度脂蛋白(lipoprotein LDL)具有异质性, 由一系列大小、密度和化学组成各异的颗粒组成。血浆甘油三酯水平越高, 生成的小而密LDL 越多。近年来对LDL 亚组份与冠心病的关系进行了深入的研究, 认为小而密LDL 在动脉粥样硬化的发生中起重要作用, 是冠心病的危险因子。小而密LDL 亚组分比密度较低的较大颗粒更具有致动脉硬化性, 可能与其更易被氧化、诱导内皮细胞表达粘附因子有关。 相似文献
98.
Paula Renee Chen Sangsu Shin Young Min Choi Elizabeth Kim Jae Yong Han Kichoon Lee 《International journal of molecular sciences》2016,17(3)
In avians, yolk synthesis is regulated by incorporation of portomicrons from the diet, transport of lipoproteins from the liver, and release of lipids from adipose tissue; however, the extent to which lipolysis in adipose tissue contributes to yolk synthesis and egg production has yet to be elucidated. G0/G1 switch gene 2 (G0S2) is known to bind and inhibit adipose triglyceride lipase (ATGL), the rate-limiting enzyme in lipolysis. The objective of this study was to determine whether overexpression of the G0S2 gene in adipose tissue could successfully inhibit endogenous ATGL activity associated with egg laying. Two independent lines of transgenic quail overexpressing G0S2 had delayed onset of egg production and reduced number of eggs over a six-week period compared to non-transgenic quail. Although no differences in measured parameters were observed at the pre-laying stage (5 weeks of age), G0S2 transgenic quail had significantly larger interclavicular fat pad weights and adipocyte sizes and lower NEFA concentrations in the serum at early (1 week after laying first egg) and active laying (5 weeks after laying first egg) stages. Overexpression of G0S2 inhibited lipolysis during early and active laying, which drastically shifted the balance towards a net accumulation of triacylglycerols and increased adipose tissue mass. Thereby, egg production was negatively affected as less triacylglycerols were catabolized to produce lipids for the yolk. 相似文献
99.
Tomohisa Nagano Nobuyoshi Seki Yoichi Tomita Tomonori Sugita Yuta Aida Munenori Itagaki Satoshi Sutoh Hiroshi Abe Akihito Tsubota Yoshio Aizawa 《International journal of molecular sciences》2015,16(9):20576-20594
Reduced low-density lipoprotein (LDL) cholesterol level is a characteristic feature of dyslipidemia in chronic hepatitis C virus (HCV) infection. However, abnormality in serum triglyceride (TG) has not been fully investigated. To clarify the impact of HCV genotype 1b (G1b) infection and advanced fibrosis on serum TG profiles, TG concentrations in lipoprotein fractions were examined in fasting sera from 185 subjects with active or cleared HCV infection by high-performance liquid chromatography. Serum lipoproteins were fractionated into four classes: chylomicron, very low-density lipoprotein (VLDL), LDL, and high-density lipoprotein (HDL). Then, the significance of HCV G1b infection on TG levels in each lipoprotein fraction was determined using multiple regression models. We found that active HCV G1b infection was positively associated with high HDL-TG levels and low VLDL-TG levels, independent of other factors included in the regression model. In VLDL sub-fractions, active HCV infection was only found to be associated with low levels of large VLDL-TG. Similarly, advanced liver fibrosis in chronic HCV G1b infection was associated with high levels of LDL-TG, HDL-TG, and small VLDL-TG, independent of other clinical factors. These findings indicate that active HCV G1b infection and advanced fibrosis are closely associated with abnormal serum TG profiles. 相似文献
100.
Low-calorie triglyceride synthesis by lipase-catalyzed esterification of monoglycerides 总被引:2,自引:0,他引:2
Monoglycerides of erucic acid (C22:1, Δ13), prepared by conventional methods, were reacted with caprylic acid (octanoic acid, C8.0) by using lipases as catalysts with the intention of synthesizing a triglyceride that contains two molecules of caprylic
acid and one molecule of erucic acid (caprucin). The reaction was carried out by mixing lipase powder, a small quantity of
water, and the reactants in a temperature-controlled stirred batch reactor. Organic solvents or emulsifying agents were not
required. When the nonspecific lipase fromPseudomonas cepacia was used, a yield of approximately 37% caprucin was obtained, together with a complex mixture of di- and triglycerides that
resulted from the random transesterification of the erucic acid. The fatty acid-specific lipase fromGeotrichum candidum promoted minimal transesterification of erucic acid and resulted in a yield of 75% caprucin and approximately 10% interesterification
products. Lipase fromCandida rugosa exhibited a similar, although less pronounced, specificity to that fromG. candidum and promoted more transesterification of erucic acid. Optimum conditions forG. candidum lipase were at 50°C and an initial water content of 5.5%. After the reaction, erucic acid was converted to behenic acid by
hydrogenation, thereby converting caprucin into caprenin, a commercially available low-calorie triglyceride. 相似文献