全文获取类型
收费全文 | 206篇 |
免费 | 16篇 |
国内免费 | 2篇 |
专业分类
综合类 | 2篇 |
化学工业 | 127篇 |
机械仪表 | 3篇 |
轻工业 | 91篇 |
石油天然气 | 1篇 |
出版年
2023年 | 2篇 |
2022年 | 9篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 13篇 |
2017年 | 10篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 3篇 |
2012年 | 8篇 |
2011年 | 10篇 |
2010年 | 5篇 |
2009年 | 7篇 |
2008年 | 3篇 |
2007年 | 5篇 |
2006年 | 8篇 |
2005年 | 4篇 |
2004年 | 8篇 |
2003年 | 4篇 |
2002年 | 9篇 |
2001年 | 5篇 |
2000年 | 6篇 |
1999年 | 6篇 |
1998年 | 9篇 |
1997年 | 8篇 |
1996年 | 10篇 |
1995年 | 3篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有224条查询结果,搜索用时 15 毫秒
71.
72.
M.G. Zenobi T.L. Scheffler J.E. Zuniga M.B. Poindexter S.R. Campagna H.F. Castro Gonzalez A.T. Farmer B.A. Barton J.E.P. Santos C.R. Staples 《Journal of dairy science》2018,101(7):5902-5923
The objectives were to determine the optimal feeding amount of choline in a ruminally protected form to reduce the triacylglycerol (TAG) concentration in liver and to increase TAG in blood plasma of dairy cows. Pregnant, nonlactating multiparous Holstein cows (n = 77) were blocked by body condition score (3.59 ± 0.33) and assigned to treatment at 64 ± 10 d before calculated calving date. Dietary treatments were top-dressing of 0, 30, 60, 90, or 120 g/d of ruminally protected choline (RPC; Balchem Corp., New Hampton, NY) ions to supply the equivalent of 0, 6.5, 12.9, 19.4, and 25.8 g/d of choline ions. Diets were formulated to exceed nutrient requirements for maintenance and pregnancy and fed in ad libitum amounts for the first 5 d. From d 6 to 15, cows were restricted to consume approximately 31% of their net energy requirements to simulate early lactating cows in negative energy balance. Methionine intake was maintained throughout each 15-d period. Liver was biopsied at 5 and 14 d and analyzed for TAG and glycogen. Blood was sampled on d 5 and 14 and plasma analyzed for glucose, insulin, cholesterol, β-hydroxybutyrate, long-chain fatty acids, and haptoglobin. On d 14, a mixture of saturated long-chain fatty acids, ground corn, and dried molasses (50:37:13) was offered (908 g, as-is basis) 10 h after the single daily feeding. Blood samples were collected for 19 h and plasma analyzed for TAG and cholesterol to assess apparent absorption of dietary fat. Mean dry matter intake and energy balance decreased from means of 9.5 to 3.3 kg/d and from 0.6 to ?9.2 Mcal of net energy for lactation/d during the ad libitum and restricted feeding periods, respectively. Plasma concentrations of the lipid-soluble choline biomolecules, namely total phosphatidylcholines, total lysophosphatidylcholines, and sphingomyelin, increased with choline supplementation. Feed restriction increased plasma concentrations of β-hydroxybutyrate and free long-chain fatty acids, whereas those of glucose, insulin, and total cholesterol decreased. During feed restriction, concentration of hepatic TAG and plasma haptoglobin decreased linearly, whereas concentration of hepatic glycogen tended to increase quadratically with increasing intake of RPC. After fat supplementation, mean plasma concentration of TAG increased by an average of 21% with intake of RPC ions, peaking at intakes of ≥6.5 g/d of RPC ion. In summary, feeding RPC ions to cows in negative energy balance had increasing lipotropic effects on the liver when consumed up to 25.8 g/d, whereas feeding only 6.5 g/d increased concentrations of hepatic glycogen and TAG in the blood. 相似文献
73.
采用超临界CO_2萃取得到沙棘籽油和沙棘全果油,并采用气相色谱和超高效液相色谱-飞行时间质谱对其脂肪酸、sn-2位脂肪酸及甘三酯组成进行测定与分析。结果表明:沙棘籽油中亚油酸、亚麻酸和油酸的含量较多,分别为38.71%、25.66%和20.68%,这3种脂肪酸也是其主要的sn-2位脂肪酸,含量分别为46.46%、25.49%和23.02%;LOL(13.65%)、OLO(12.06%)和LLn O(11.23%)是沙棘籽油的主要甘三酯类型;沙棘全果油中棕榈油酸(36.86%)、棕榈酸(27.27%)和油酸(18.00%)的含量较高,主要的sn-2位脂肪酸为棕榈油酸(45.57%)和油酸(32.06%);沙棘全果油的主要甘三酯为POPo(14.38%)、PoOPo(13.77%)和OPO(12.06%)。 相似文献
74.
以纯度为96%的α-桐酸作为对照,考察了从桐油中经NARP-HPLC分离得到的3组含共轭亚麻酸的甘油三酯对人体肿瘤细胞株ECA-109 (食管癌)、SGC-7901(胃癌)、Bel-7402(肝癌)、LS-174-T(结肠癌)、KB(口腔癌)和正常细胞株 L02(肝细胞)的细胞毒性.结果发现α-桐酸对KB、Bel-7402和SGC-7901细胞的毒性明显弱于3组含共轭亚麻酸的甘油三酯.结果提示,除了α-桐酸的共轭三烯结构是桐油甘油三酯的细胞毒性的物质基础之外,含共轭亚麻酸的甘油三酯的分子结构对其抗肿瘤功效也有重要贡献. 相似文献
75.
Medium- and long-chain triacylglycerol (MLCT) is a modified lipid containing medium- chain (C6-C12) and long-chain fatty acids (C14-C24) in the same triacylglycerol (TAG) molecule. It can be produced either through enzymatic (with 1,3 specific or nonspecific enzyme) or chemical methods. The specialty of this structured lipid is that it is metabolized differently compared to conventional fats and oils, which can lead to a reduction of fat accumulation in the body. Therefore, it can be used for obesity management. It also contains nutritional properties that can be used to treat metabolic problems. This review will discuss on the health benefits of MLCT, its production methods especially via enzymatic processes and its applications in food industries. 相似文献
76.
Marc A. Bjurlin Scott Bloomer Michael J. Haas 《Journal of the American Oil Chemists' Society》2001,78(2):153-160
Commercial lipase preparations were surveyed to determine gross composition, amounts of nonprotein impurities, and esterolytic and lipolytic activities. Most of the 34 commercial lipase preparations contained more than 80% non-proteinaceous material, with salt and carbohydrate being the most abundant materials. The tributyrin hydrolase activity of these commercial lipase preparations was determined and expressed as lipase/esterase forestomach units (LFU). Tributyrin hydrolase activity ranged from negligible (5.3 LFU/g) to very high (>1000,000 LFU/g). Aspergillus and Penicillium preparations were low in tributyrin hydrolase activity. Candida rugosa preparations were intermediate in activity. Preparations of porcine pancreas, Rhizomucor, Pseudomonas, and Rhizopus lipases exhibited a broad range of levels of activity. No relation between protein content and tributyrin hydrolase activity was observed. Isoelectric focusing of the proteins present in the preparations demonstrated the presence of between 2 and 27 isophoretically discrete bands in the isoelectric range of 3 to 9. Although there were many similarities of distribution of protein isoelectric points within genera and spcies, the preparations generally displayed unique patterns of isophoretically discrete protein bands. Lipase zymography demonstrated the presence of 0 to 7 isophoretically discrete lipase activities in each preparation, spanning the entire range of isoelectric points surveyed. 相似文献
77.
abstract The structured lipids are produced through sn-1,3-specific interesterification of soybean oil with medium-chain triacylglycerol (MCT) in continuous reactions catalyzed by Thermomyces lanuginos... 相似文献
78.
Marcel S. F. Lie Ken Jie C. C. Lam Mohammed Khysar Pasha 《Journal of the American Oil Chemists' Society》1996,73(5):557-562
13C nuclear magnetic resonance (NMR) spectroscopic analysis of the whole oil (triacylglycerols) ofBiota orientalis seeds confirms the presence of oleate [18:1(9Z)], linoleate [18:2(9Z, 12Z)], linolenate [18:3((9Z, 12Z, 15Z)], 20:3 (5Z,
11Z, 14Z), 20:4(5Z, 11Z, 14Z, 17Z), and saturated fatty acids in the acyl groups by comparing the observed carbon shifts with
previously established shift data for model triacylglycerols. This technique shows that the saturated, 20:3 and 20:4 fatty
acids are distributed mainly in the α-acyl positions, whereas oleate, linoleate, and linolenate are randomly acylated to the
α- and β-positions of the glycerol “backbone”. Stereospecific hydrolysis of theBiota oil with pancreatic lipase, followed by chromatographic analysis of fatty esters, reveals the presence of trace amounts of 16:0(0.7%),
18:0(0.5%), 20:3 (0.4%), and 20:4 (1.3%) in the β-position of the glycerol “backbone”, which are undetectable by13C NMR technique on the whole oil. Semiquantitative assessment of the13C NMR signal intensities gives the relative percentages of the fatty acid distribution as: saturated 16:0, 18:0 (12.0% α-acyl),
oleate (7.7% α-acyl 8.7% β-acyl), total linoleate and linolenate (31.7% α-acyl; 24.2% βacyl), total 20:3 and 20:4 (15.7% α-acyl).
The13C NMR spectroscopic analysis of carrot seed oil identifies the presence of saturated (18:0), 18:1(6Z), 18:1(9Z), and 18:2(9Z,
12Z). The saturated fatty acid is found in the α-acyl positions. Semi-quantitative assessment of the signal intensities gives
the relative percentages of the fatty acids as: 18:0 (4.5% α-acyl), 18:1(6Z) (49.6% α-acyl; 19.7% β-acyl), oleate (6.5% α-acyl;
8.6% β-acyl) and linoleate (5.2% α-acyl; 6.9% β-acyl). 相似文献
79.
J. -P. Kurvinen O. Sjövall H. Kallio 《Journal of the American Oil Chemists' Society》2002,79(1):13-22
Triacylglycerol (TAG) molecular weight distribution and regioisomeric structure of selected molecular weight species in human
milk and in 32 human milk substitutes was determined. Negative ion chemical ionization mass spectrometry was used to determine
the molecular weight distribution and collisionally induced dissociation tandem mass spectrometry applied to identify the
sn-2 and sn-1/3 positions of fatty acids in TAG. The main molecular weight species of human milk TAG in decreasing order of abundance
were 52∶2, 52∶3, 52∶1, 54∶3, 50∶2, 50∶1, 54∶4, 48∶1, 54∶2, 48∶2, 46∶1, 52∶4, and 50∶3 (acyl carbon number/number of double
bonds), constituting 83 mol% of total TAG molecular species. In human milk substitutes, the proportion of the corresponding
molecular weight species varied from 33 to 87 mol%. The main TAG regioisomers within the molecular weight species 52∶2, 52∶3,
and 50∶1 in human milk were 18∶1-16∶0-18∶1 (83 mol%), 18∶1-16∶0-18∶2 (83 mol%), and 18∶1-16∶0-16∶0 (80 mol%), respectively.
In human milk substitutes, the corresponding proportions varied in a wide range of 0–82 mol%, 0–100 mol%, and 0–73 mol%, respectively.
Although TAG structures in some human milk substitutes closely resembled those in human milk, the great variation among samples
leads to the conclusion that it is still possible to improve the TAG composition in human milk substitutes by applying novel
methods to synthesize structured TAG. 相似文献
80.
José Ángel Cahua-Pablo Jaime Héctor Gómez-Zamudio Carlos Alberto Reséndiz-Abarca Vianet Argelia Tello-Flores Yesica Eulogio-Metodio Marco Antonio Ramírez-Vargas Miguel Cruz Luz del Carmen Alarcón-Romero Inés Matia-García Linda Anahí Marino-Ortega Ma. Isabel Zubillaga-Guerrero Eugenia Flores-Alfaro 《Lipids》2022,57(2):105-114
Dyslipidemia is the main risk factor for coronary artery disease and is characterized by alterations in concentrations of lipids, including low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), and triacylglycerols. The participation of several genes in the development of dyslipidemia has been evidenced. Genetic variants in SLC22A1 have been associated with elevated cholesterol and LDL-c levels. The aim of this study was to evaluate the association between single-nucleotide polymorphisms (SNPs) in the SLC22A1 gene with atherogenic risk lipid levels in Mexican women. Anthropometric and biochemical measurements were performed, and four SNPs in SLC22A1 were genotyped by real-time polymerase chain reaction. The Hardy–Weinberg equilibrium was verified, and haplotype frequencies were calculated. We found significant differences between the allele frequencies of the SNPs analyzed with those reported in Mexico and in the world, which could be due to differences in the historical admixture of the women studied. Generalized linear models were evaluated to determine the association between genotypes and haplotypes with lipids levels. We identified a significant increase in total cholesterol and LDL-c levels in women who were carriers of the GA and AG genotypes of the polymorphisms rs628031 and rs594709, respectively, significant effect that is also shown in a dominant inheritance model. Interestingly, we identified an important relationship of the AGC-GAT haplotype with the elevation in LDL-c levels and AGA-GAT haplotype with the elevation in HDL-c levels. On the other hand, we found a strong linkage disequilibrium between the polymorphisms studied. Our results show that variants in the SLC22A1 gene influence serum levels of atherogenic risk lipids, suggesting that these variants probably affect the function of organic cation transporter-1 and therefore, on the regulation of lipid metabolism. 相似文献