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31.
The main biochemical function of the tocopherols is believed to be the protection of polyunsaturated fatty acids (PUFA) against
peroxidation. A critical question that must be asked in reference to this is whether there is a biochemical link between the
tocopherol levels and the degree of unsaturation in vegetable oils, the main source of dietary PUFA and vitamin E. We used
a mathematical approach in an effort to highlight some facts that might help address this question. Literature data on the
relative composition of fatty acids (16:0, 16:1, 18:0, 18:1, 18:2, and 18:3) and the contents of tocopherols (α-, β-, δ-,
and γ-tocopherol) in 101 oil samples, including 14 different botanical species, were analyzed by principal-component analysis
and linear regression. There was a negative correlation between α- and γ-tocopherols (r=0.633, P<0.05). Results also showed a positive correlation between linoleic acid (18:2) and α-tocopherol (r=0.549, P<0.05) and suggested a positive correlation between linolenic acid (18:3) and γ-tocopherol. 相似文献
32.
Lucian M. Rusnac Octavian Floarea Radu V. Vladea 《Journal of the American Oil Chemists' Society》1992,69(4):384-386
Continuous hydrogenation of industrially refined soybean oil with Harshaw Ni catalyst was achieved in a slurry column equipped
with Sulzer SMV motionless mixers. The influence of the operating parameters (temperature, pressure, catalyst concentration
and gas velocity) was investigated. The presumption that, in this equipment, the liquid-solid mass transfer limits the rate
of the process is in good agreement with the experimental data. 相似文献
33.
Free primary alcohols in oils and waxes from germs,kernels and other components of nuts,seeds, fruits and cereals 总被引:2,自引:0,他引:2
Kazuko Kawanishi Kumlko Aoki Yohei Hashimoto Akira Matsunobu 《Journal of the American Oil Chemists' Society》1991,68(11):869-872
The composition of free primary alcohols in oils and waxes obtained from the germ, kernel, seed coat, shell and skin (peel)
of various nuts, seeds, fruits and cereals and from the chrysalis of silkworm was examined. These alcohols are usually present
in small amounts, along with large quantities of hydrocarbons, esters and glycerides in oils and waxes. Thus, it is necessary
to remove hydrocarbons, esters and glycerides to analyze the alcohols. We found that preparative reverse-phase thin-layer
chromatography (TLC) was the best way to isolate alcohols from oils and waxes. Gas liquid chromatography (GLC) then detected
hexacosanol, octacosanol and triacontanol in the oils and waxes. Octacosanol usually was the predominant alcohol. Relationships
between the organs from nuts, seeds, fruits and cereals and the contents of octacosanol are suggested. For example, degermed
kernels contained two times more octacosanol than the germ, and the skin coat and shell contained one-half and one-fortieth
the octacosanol of the germ, respectively. 相似文献
34.
废餐饮油制备生物柴油研究现状与应用前景 总被引:5,自引:0,他引:5
介绍了利用废餐饮油制备生物柴油的研究现状与应用前景;叙述了酸催化、碱催化和酶催化的酯交换制备生物柴油工艺,以及每种工艺的优缺点.阐述了我国利用餐饮废油制取生物柴油的意义和利用餐饮废油制取生物柴油的商业化生产的可行性. 相似文献
35.
Craig A. Dorschel 《Journal of the American Oil Chemists' Society》2002,79(8):749-753
A study of processed peanut oil was undertaken to assess the utility of HPLC combined with tandem MS to obtain data easily
regarding the number of TAG of fats and oils and their FA composition. Mass chromatograms and spectra corresponding to only
TAG of a single M.W. were obtained for the full range of TAG in the sample. Analysis of the mass spectra allowed the identification
of more than 160 TAG in the sample by their FA composition. In addition, it was possible to estimate relative abundances of
the TAG and suggest the position of the FA on glycerol for a limited number of cases. This technique greatly simplifies the
task of assigning FA to coeluting TAG and facilitates identification of TAG present in trace quantities in mixtures, with
possible application in circumstances where such trace TAG could be significant markers. Results are quickly obtained without
extensive sample preparation or prefractionation of the sample. 相似文献
36.
Alejandrina Campanella Miguel A. Baltans 《European Journal of Lipid Science and Technology》2004,106(8):524-530
Vegetable oil epoxides (oxiranes) are customarily manufactured using acetic acid (AA) as oxygen carrier and reactant source, in aqueous/organic media. Further attack of the oxirane ring by AA proceeds in this acid‐catalyzed process, lowering yield. We report a study of the degradation of the ring by water‐solvated AA, using Amberlite IR‐120 as heterogeneous catalyst. The ring opening with solvated AA was found to be first order with respect to the concentration of epoxide groups and second order with respect to the carboxylic acid, with an activation energy of 58.7 ± 0.42 kJ mol?1. This value is within the range found in liquid‐liquid systems (51.3–66.3 kJ mol?1). Yet, using IR‐120, the degradation increases identically either by adding more mass of catalyst or by reducing its particle diameter while keeping the total mass constant, as both situations lead to higher external (exposed) area of the acidic catalyst (i.e., free protons associated to the sulfonic group) on the outer surface of the ion exchange resin beads. These free protons, in turn, become available to catalyze the attack on the oxirane groups of the long‐chain fatty acids, which cannot enter (diffuse) into the gel phase of the resin. Despite the unavoidable presence of surface‐exposed protons, the degradation can be reduced by several orders of magnitude – for similar process conditions – by using this type of heterogeneous catalysts instead of mineral acids. 相似文献
37.
Rosario?Zamora Gemma?Gómez Francisco?J.?HidalgoEmail author 《Journal of the American Oil Chemists' Society》2002,79(3):267-272
13C NMR spectra of oil fractions obtained chromatographically from 109 vegetable oils were obtained and analyzed to evaluate
the potential use of those fractions in the classification of vegetable oils and to compare the results with the NMR analysis
of complete oils. The oils included the following: virgin olive oils from different cultivars and regions of Europe and north
Africa; “lampante” olive, refined olive, refined olive pomace, hazelnut, rapeseed, high-oleic sunflower, corn, grapeseed,
soybean, and sunflower oils; and mixtures of virgin olive oils from different geographical origins. Oils were divided into
two sets of samples. The training set (98 samples) was employed to select the variables that resulted in significant discrimination
among the different oil classes. By using stepwise discriminant analysis, more than 98% of correct validated assignments were
obtained; these results were confirmed when applied to the test set (11 blind samples). Results suggest that the use of oil
fractions considerably increases the discriminating power of NMR in the analysis of vegetable oils. 相似文献
38.
The oxidative stabilities of one canola oil and six soybean oils of various fatty acid compositions were compared in terms
of peroxide values, conjugated dienoic acid values and sensory evaluations. Two of the soybean oils (Hardin and BSR 101) were
from common commercial varieties. The other four soybean oils were from experimental lines developed in a mutation breeding
program at Iowa State University that included A17 with 1.5% linolenate and 15.2% palmitate; A16 with 2% linolenate and 10.8%
palmitate; A87-191039 with 2% linolenate and 29.6% oleate; and A6 with 27.5% stearate. Seed from the soybean genotypes was
cold pressed. Crude canola oil was obtained without additives. All oils were refined, bleached and deodorized under laboratory
conditions with no additives and stored at 60°C for 15 days. The A17, A16, A87-191039 and A6 oils were generally more stable
to oxidation than the commercial soybean varieties and canola oil as evaluated by chemical and sensory tests. Canola oil was
much less stable than Hardin and BSR 101 oils by both chemical and sensory tests. The peroxide values and flavor scores of
oils were highly correlated with the initial amounts of linolenate (r=0.95, P=0.001). Flavor quality and flavor intensity
had negative correlations with linolenate, (r=−0.89, P=0.007) and (r=−0.86, P=0.013), respectively. 相似文献
39.
L.?Alonso M.?J.?Fraga M.?JuárezEmail author P.?Carmona 《Journal of the American Oil Chemists' Society》2002,79(1):1-6
A Fourier transform infrared spectroscopic procedure was used to analyze 34 edible fats (22 shortenings and 12 vegetable margarines)
as neat fats (IRNF) to determine their total trans fatty acid (TFA) content. The sloping baseline was corrected with a reference spectrum based on a nonprocessed olive oil.
The calibration was done using seven partially hydrogenated fats with an individual TFA content previously determined by the
combination of gas chromatography (GC) with argentation thin-layer chromatography. Taking into account the different absorptivities
of various trans isomers, different correction factors were calculated using the calibration standards (0.83 and 1.71 for single trans bonds in both diethylene and triethylene and for trans, trans-diethylene fatty acids, respectively) and applied to calculate the total TFA of samples. Moreover, the samples were converted
to their methyl esters and reanalyzed following the same procedure (IRFAME). Differences in TFA content of fats were not found when a t-test was used to compare the results obtained by IRNF vs. either IRFAME or GC, suggesting that IR of neat fats could be used, thus avoiding the need to prepare sample solutions in organic solvents
and to prepare fatty acid methyl esters. The mean TFA content (determined by IRNF) of a representative group of Spanish shortenings (22 samples) that varied widely in terms of fat sources, processes, and
purposes (bakery, sandwiches, ice cream, coatings, chocolate coverings) was 6.55±11.40%, although more than 54% contained
<3% of TFA. Fatty acid composition of shortenings by direct GC using a 100-m polar cyanopolysiloxane capillary column indicated
that the mean trans-18∶2 isomer content was 0.58%, ranging from 0.9 to 3.4%. Small amounts of trans-18∶3 isomers (<0.3%) were observed in 18 of the 22 shortenings studied; the maximal value was <2%. The mean value of the
fraction saturated+TFA of shortenings was high (59.95±12.73%), including two values higher than 83%. 相似文献
40.
Soybeans produced by induced mutation breeding and hybridization were cracked, flaked and hexane-extracted, and the recovered
crude oils were processed to finished edible oils by laboratory simulations of commercial oil-processing procedures. Three
lines yielded oils containing 1.7, 1.9 and 2.5% linolenic acid. These low-linolenic acid oils were evaluated along with oil
extracted from the cultivar Hardin, grown at the same time and location, and they were processed at the same time. The oil
from Hardin contained 6.5% linolenic acid. Low-linolenic acid oils showed improved flavor stability in accelerated storage
tests after 8 d in the dark at 60°C and after 8h at 7500 lux at 30°C, conditions generally considered in stress testing. Room
odor testing indicated that the low-linolenic oils showed significantly lower fishy odor after 1 h at 190°C and lower acrid/pungent
odor after 5 h. Potatoes were fried in the oils at 190°C after 5, 10 and 15 h of use. Overall flavor quality of the potatoes
fried in the low-linolenic oils was good and significantly better after all time periods than that of potatoes fried in the
standard oil. No fishy flavors were perceived with potatoes fried in the low-linolenic oils. Total volatile and polar compound
content of all heated oils increased with frying hours, with no significant differences observed. After 15 h of frying, the
free fatty acid content in all oils remained below 0.3%. Lowering the linolenic acid content of soybean oil by breeding was
particularly beneficial for improved oil quality during cooking and frying. Flavor quality of fried foods was enhanced with
these low-linolenic acid oils. 相似文献