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Wolfgang Sümmermann Hans Rohleder und Friedhelm Korte 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1978,166(3):137-144
Zusammenfassung Im Rahmen eines koordinierten Forschungsprogramms des BMFT wurde eine orientierende Studie an möglichst repräsentativen Stichproben durchgeführt. Trotz relativ großer Streubreiten zeichnen sich die Bereiche der wichtigsten Lebensmittelgruppen deutlich voneinander ab mit Mittelwerten um 0,005 /g für fettarme pflanzliche Grundnahrungsmittel, um 0,05 /g für pflanzliche Nahrungsfette, um 0,3 /g für Milch-, Käse und Butterfette, um 0,15 /g für sonstige Nahrungsfette von Landtieren, um 0,03 /g für Hühnereier und um 10 /g für Fischfett. Wichtet man die Gehalte entsprechend der durchschnittlichen Diät in der BRD, so ergibt sich eine tägliche PCB-Aufnahme von rund 29 aus tierischen Fetten und rund 6 aus den übrigen Lebensmitteln. Die Gesamtaufnahme von ca. 35 g pro Tag und capita entspricht etwa dem Wert, der von der WHO als ADI-Wert für HCB (Hexachlorbenzol) in Aussicht genommen wurde.
Polychlorinated biphenyls (PCB) in foodThe situation in the Federal Republic of Germany
Summary In a coordinated research program of the Federal Ministry of Research and Technology (BMFT), a screening study was carried out with representative samples. In spite of rather large ranges of PCB concentrations, the most important food-stuffs show clearly defined clusters with mean values of approx. 0.005 /g in low fat food components of plant origin such as cereals or potatoes, approx. 0.05 /g in vegetable fats, approx. 0.3 /g in fat from milk, butter and cheese, approx. 0.15 gg/g in animal fat, approx. 0.03 in chicken eggs and approx. 10 /g in fish fat. Considering the mean diet in the FRG, a daily PCB intake of about 29 g from animal fat and of 6 from the other food-stuffs results. The total intake of about 35 g per day and capita is almost the same as the figure conditionally suggested by the WHO as the acceptable daily HCB (hexachlorobenzene) intake.相似文献
4.
Andrey Frolov Kimberly Miller Jeffrey T. Billheimer Tae-Hyeon Cho Friedhelm Schroeder 《Lipids》1997,32(11):1201-1209
Although it was recently recognized that sterol carrier protein-2 (SCP-2) interacts with fatty acids, little is known regarding the specificity of SCP-2 for long-chain fatty acids or branched-chain fatty-acid-like molecules. Likewise the location of the fatty-acid binding site within SCP-2 is unresolved. A fluorescent cis-parinaric acid displacement assay was used to show that SCP-2 optimally interacted with 14–22 carbon chain lipidic molecules: polyunsaturated fatty acids > monounsaturated, saturated > branched-chain isoprenoids > branched-chain phytol-derived fatty acids. In contrast, the other major fatty-acid binding protein in liver, fatty-acid binding protein (L-FABP), displayed a much narrower carbon chain preference in general: polyunsaturated fatty acids > branched-chain phytol-derived fatty acids > 14- and 16-carbon saturated > branched-chain isoprenoids. However, both SCP-2 and l-FABP displayed a very similar unsaturated fatty-acid specificity profile. The presence and location of the SCP-2 lipid binding site were investigated by fluorescence energy transfer. The distance between the SCP-2 Trp50 and bound cis-parinaric acid was determined to be 40 Å. Thus, the SCP-2 fatty-acid binding site appeared to be located on the opposite side of the SCP-2 Trp50. These findings not only contribute to our understanding of the SCP-2 ligand binding site but also provide evidence suggesting a potential role for SCP-2 and/or L-FABP in metabolism of branched-chain fatty acids and isoprenoids. 相似文献
5.
Wickerhamomyces anomalus killer strains are important for fighting pathogenic yeasts and for controlling harmful yeasts and bacteria in the food industry. Targeted disruption of key genes in β‐glucan synthesis of a sensitive Saccharomyces cerevisiae strain conferred resistance to the toxins of W. anomalus strains BS91, BCA15 and BCU24 isolated from olive brine. Competitive inhibition of the killing activities by laminarin and pustulan refer to β‐1,3‐ and β‐1,6‐glucans as the main primary toxin targets. The extracellular exoglucanase‐encoding genes WaEXG1 and WaEXG2 from the three strains were sequenced and were found to display noticeable similarities to those from known potent W. anomalus killer strains. Accession Nos for WaEXG1 genes for the strains in brackets are JQ734563 (BS91), JQ734564 (BCA15) and JQ734565 (BCU24); for WaEXG2 genes JQ734566 (BS91), JQ734567 (BCA15) and JQ734568 (BCU24), respectively. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
6.
Although fatty acid-binding proteins (FABP) differentially affect fatty acid uptake, nothing is known regarding their role(s)
in determining cellular phospholipid levels and phospholipid fatty acid composition. The effects of liver (L)- and intestinal
(I)-FABP expression on these parameters were determined using stably transfected L-cells. Expression of L- and I-FABP increased
cellular total phospholipid mass (nmol/mg protein) 1.7- and 1.3-fold relative to controls, respectively. L-FABP expression
increased the masses of choline glycerophospholipids (ChoGpl) 1.5-fold, phosphatidylserine (PtdSer) 5.6-fold, ethanolamine
glycerophospholipids 1.4-fold, sphingomyelin 1.7-fold, and phosphatidylinositol 2.6-fold. In contrast, I-FABP expression only
increased the masses of ChoGpl and PtdSer, 1.2- and 3.1-fold, respectively. Surprisingly, both L- and I-FABP expression increased
ethanolamine plasmalogen mass 1.6- and 1.1-fold, respectively, while choline plasmalogen mass was increased 2.3- and 1.7-fold,
respectively. The increase in phospholipid levels resulted in dramatic 48 and 33% decreases in the cholesterol-to-phospholipid
ratio in L- and I-FABP expressing cells, respectively. L-FABP expression generally increased polyunsaturated fatty acids,
primarily by increasing 20∶4n−6 and 22∶6n−3, while decreasing 18∶1n−9 and 16∶1n−7. I-FABP expression generally increased only
20∶4n−6 proportions. Hence, expression of both I- and L-FABP differentially affected phospholipid mass, class composition,
and acyl chain composition. Although both proteins enhanced phospholipid synthesis, the effect of L-FABP was much greater,
consistent with previous work suggesting that these two FABP differentially affect lipid metabolism. 相似文献
7.
Major advances in understanding cholesterol dynamics and the role that cholesterol plays in vascular disease have recently
been made. The brain is an organ that is highly enriched in cholesterol, but progress toward understanding brain cholesterol
dynamics has been relatively limited. This review examines recent contributions to the understanding of brain cholesterol
dynamics, focusing on extracellular and intracellular lipid carrier proteins, membrane cholesterol domains, and emerging evidence
linking an association between cholesterol dynamics and Alzheimer's disease. 相似文献
8.
The conversion of a number of alcohols, ethers, ketones, aldehydes, carboxylic acids, esters, and cyclic compounds and their mixtures on H-ZSM-5 at 673 K was investigated. These compounds can be easily converted to aromatic hydrocarbons if the C/H ratio of the molecule fragment, remaining after elimination of oxygen as water, is less than 0.62. At higher C/H ratios, coking of the catalyst increases, thus reducing its lifetime, a difficulty which can be overcome by hydrogenation of these compounds prior to their conversion over H-ZSM-5. A procedure is proposed for converting at least a part of organic waste chemicals to valuable products instead of burning them. 相似文献
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Foued Ameur Paul Fischer Klaus-U. Höffgen Friedhelm Meyer auf der Heide 《Acta Informatica》1996,33(7):621-630
A pac-learning algorithm is -space bounded, if it stores at most examples from the sample at any time. We characterize the -space learnable concept classes. For this purpose we introduce the compression parameter of a concept class and design our Trial and Error Learning Algorithm. We show : is -space learnable if and only if the compression parameter of is at most . This learning algorithm does not produce a hypothesis consistent with the whole sample as previous approaches e.g. by Floyd,
who presents consistent space bounded learning algorithms, but has to restrict herself to very special concept classes. On
the other hand our algorithm needs large samples; the compression parameter appears as exponent in the sample size. We present
several examples of polynomial time space bounded learnable concept classes: – all intersection closed concept classes with
finite VC–dimension. – convex -gons in . – halfspaces in . – unions of triangles in . We further relate the compression parameter to the VC–dimension, and discuss variants of this parameter.
Received May 24, 1994 / July 4, 1995 相似文献