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41.
Alessandro Capuani Jürgen Behr Elke K. Arendt Rudi F. Vogel 《European Food Research and Technology》2014,238(6):979-988
The influence of reducing and oxidizing buckwheat sourdoughs on the rheological, protein, and bread properties of buckwheat and brown rice flour was investigated. Batters and breads prepared with chemically acidified doughs, fresh pre-doughs, and fresh pre-doughs containing glutathione (3 mM) were used as controls. No significant differences were observed after the addition of reducing and oxidizing sourdoughs in all trials. Proteolysis was observed after proofing time in buckwheat and brown rice batters, respectively. Acidified doughs increased the elasticity and the gelatinization temperature of buckwheat batters. No notable microstructure changes were detected in brown rice batters. The extension of fermentation time in sourdough caused a slight decrease in bread volumes in all trials. Sourdoughs increased the bread volume and decreased the crumb hardness of buckwheat breads. In trials with brown rice flour, the addition of sourdough did not show relevant volume differences as compared to the controls, except big voids in sourdough bread crumb. Linear correlations between hardness, volume, and cells’ density were observed. However, no clear correlations among rheological parameters and bread characteristics could be detected. These results indicated that the applied strains were responsible for the leavening capacity of the yeast during the proofing time and for crumb structure in trials with buckwheat and brown rice flour. Applied sourdoughs were able to change the molecular, and bread properties of buckwheat and brown rice bread. 相似文献
42.
Precursor-Derived Si-B-C-N Ceramics: Oxidation Kinetics 总被引:1,自引:0,他引:1
Elke Butchereit Klaus G. Nickel Anita Müller 《Journal of the American Ceramic Society》2001,84(10):2184-2188
The oxidation behavior of three precursor-derived ceramics—Si4.46 BC7.32 N4.40 (AMF2p), Si2.72 BC4.51 N2.69 (AMF3p), and Si3.08 BC4.39 N2.28 (T2/1p)—was investigated at 1300° and 1500°C. Scale growth at 1500°C in air can be approximated by a parabolic rate law with rate constants of 0.0599 and 0.0593 μm2 /h for AMF3p and T2/1p, respectively. The third material does not oxidize according to a parabolic rate law, but has a similar scale thickness after 100 h. The results show that at least within the experimental times these ceramics develop extremely thin scales, thinner than pure SiC or Si3 N4 . 相似文献
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Francisco A Toms‐Barbern Isabel Martos Federico Ferreres Branka S Radovic Elke Anklam 《Journal of the science of food and agriculture》2001,81(5):485-496
The HPLC phenolic profiles of 52 selected unifloral honey samples produced in Europe were analysed to detect possible markers for the floral origin of the different honeys. Lime‐tree (five markers), chestnut (five markers), rapeseed (one marker), eucalyptus (six markers) and heather (three markers) honeys had specific markers with characteristic UV spectra. In addition, the flavanone hesperetin was confirmed as a marker for citrus honey, as well as kaempferol for rosemary honey and quercetin for sunflower honey. Abscisic acid, which had been reported to be a possible marker for heather honey, was also detected in rapeseed, lime‐tree and acacia honeys. Ellagic acid in heather honey and the hydroxycinnamates caffeic, p‐coumaric and ferulic acids in chestnut, sunflower, lavender and acacia honeys were also detected. The characteristic propolis‐derived flavonoids pinocembrin, pinobanksin and chrysin were present in most samples in variable amounts. © 2001 Society of Chemical Industry 相似文献
46.
Elke Rauscher-Gabernig Robert Gabernig Werner Brueller Roland Grossgut Friedrich Bauer Peter Paulsen 《European Food Research and Technology》2012,235(2):209-220
Biogenic amines (histamine, tyramine, putrescine, cadaverine, agmatine, spermidine and spermine) are nitrogenous compounds. They occur naturally in living organisms and are involved in many biological processes. Nonetheless, high amounts in food may be hazardous to human health. The diamines putrescine and cadaverine in food can potentiate the effects of simultaneously ingested histamine. In protein-rich foods, high concentrations of these diamines are indicative for hygienic deficiencies in the food chain. Even though being formed endogenously and being essential for some physiological metabolic pathways, both diamines are known as precursors for carcinogenic nitrosamines. Putrescine also plays a certain role in tumour growth. Nevertheless, no tolerable levels in foods have been established so far. The present study suggests tolerable levels in cheese, fermented sausages, fish, sauerkraut and seasonings that are based on toxicological threshold levels, occurrence of diamines in foods and food consumption in Austria. Average daily intake of putrescine via fermented food was calculated to be 6.8 (female adults) and 8.8 (male adults) mg per person. Respective numbers for cadaverine were 9.8 and 11.6 mg per person and day. For putrescine, proposed maximum tolerable levels for sauerkraut, fish, cheese, fermented sausages and seasonings are 140, 170, 180, 360 and 510 mg/kg, respectively. Likewise, for cadaverine, in sauerkraut, fish, cheese, fermented sausages and seasonings, maximum tolerable levels are 430, 510, 540, 1,080 and 1,540 mg/kg, respectively. These limits can be met by current manufacturing practices, as ascertained from the results of our own studies and from literature. Admittedly, only few data are published on toxicological threshold levels of these diamines, which mean that these tolerable levels are associated with some uncertainty. 相似文献
47.
Christoph von Holst Anne Müller Erland Björklund Elke Anklam 《European Food Research and Technology》2001,213(2):154-160
This paper comprises a simplified method for the determination of polychlorinated biphenyls (PCBs) in food and feedingstuffs. The method includes a cold column extraction step, a simple clean-up with concentrated sulfuric acid, and a final determination of the PCBs using gas chromatography-mass spectrometry (GC/MS). An in-house validation study was performed to establish method performance characteristics such as decision limit, detection capability, trueness and precision of the method. To determine these characteristics both certified reference materials and spiked samples were utilized. The decision limit and the detection capability of the individual PCB congeners in food were 2 ng/g and 3 ng/g fat, respectively, while corresponding figures for feedingstuffs were 7 ng/g and 9 ng/g fat, respectively. The coefficient of variation (CV) varied from 2% to 5% for food on the 10 ng/g fat level and from 2% to 6% for feedingstuffs on the 25 ng/g fat level. The recoveries of the individual PCB congeners varied from 88% to 107%, indicating good correspondence with internationally recognized criteria for the performance characteristics of analytical methods. The robustness of the method was investigated by employing a factorial design methodology to determine the influence of six experimental factors on the results of the analysis. This clearly demonstrated that the method is fit for surveillance of PCBs in food and feedingstuffs, even though some care has to be taken with the solvent volume during the cold column extraction step as well as the addition of the standard to the sample. Additionally, the investigation clearly demonstrates that in-house validation approaches may be used for determination of the overall performance of analytical methods. 相似文献
48.
Carmelina Summa Fernando Cordeiro Raposo Josephine McCourt Roberto Lo Scalzo Karl-Heinz Wagner Ibrahim Elmadfa Elke Anklam 《European Food Research and Technology》2006,222(3-4):368-375
The free-radical scavenging activity of cocoa samples subjected to different roasting treatments has been determined. The
samples (raw, pre-roasted and roasted) were separated into four molecular weight fractions per sample (>30, 30–10, 10–5, and
<5 kDa). The free-radical scavenging activity was determined with the DPPH• (1,1-dipheny-2-picrylhydrazyl), and ABTS•+ [2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)] free-radical scavenging assays for all samples. Both tests were
compared in terms of sensitivity and measurement precision, at different reaction times. Comparing the results from each test,
the free-radical scavenging activity trends were similar for each fraction but with notable differences in the sensitivity
of the assays. Analysis of the concentration of reducing substances, such as water soluble phenolics, melanoidins, carbohydrates,
etc, in these fractions by the photometric Folin–Ciocalteu assay, showed a similar pattern to the free-radical scavenging
activity trend. Moreover, this comparison showed that there were significantly (P < 0.05) more reducing substances and free-radical scavenging activity in the 10–5 kDa roasted cocoa bean fraction. 相似文献
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50.
René-Maxime Gracien Sarah C. Reitz Marlies Wagner Christoph Mayer Steffen Volz Stephanie-Michelle Hof Vinzenz Fleischer Amgad Droby Helmuth Steinmetz Sergiu Groppa Elke Hattingen Johannes C. Klein Ralf Deichmann 《Magma (New York, N.Y.)》2017,30(1):75-83