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991.
Jana E. Reetz Sebastian Zühlke Michael Spiteller Klaus Wallner 《Journal für Verbraucherschutz und Lebensmittelsicherheit》2012,7(4):283-290
The current discussion about the relevance of guttation as a water source for honey bees (Apis mellifera L.) draws attention to the activity of water foraging bees. However, due to the wide foraging range, field observations of water foraging bees are difficult to carry out. Therefore, samples of returning bees were collected in front of the entrance early in the morning as well as during the day in summer and autumn 2010. In the laboratory, honey sacs of bees without pollen or propolis were examined. Honey sac samples with a weight of ≥0.005?g were classified as successful foragers. For the determination of water or nectar foragers, the honey sac contents of successful foragers were analyzed with a refractometer. Due to the dilution and the precision of the refractometer, an accuracy of 5?% was possible. Based on the known range of sugar concentrations in nectars, the analyzed samples were divided into nectar foragers (25–65?% sugar) and water foragers (0–15?% sugar). The study reveals that nectar and water foraging bees can be discriminated by analyzing the honey sac extracts with a refractometer. In autumn, the water demand of honey bee colonies is almost exclusively covered by water collection, whereas during summer nectar is mainly used as a substitute for water. In general, water collection is not restricted to certain times of the day. 相似文献
992.
Susanne?K?gelEmail author Jürgen?Gross Christoph?Hoffmann Detlef?Ulrich 《European Food Research and Technology》2012,234(3):399-404
The study focuses on the odor-active intensity and occurrence of three methoxypyrazines in ladybird beetles, Harmonia axyridis, invasive in Europe and the USA, and Coccinella septempunctata, native in Europe, but invasive in the USA. It is known from previous studies that H. axyridis has negatively influenced the taste of wine in the USA because of releasing their hemolymph in must during harvesting. In
relation to C. septempunctata, H. axyridis had more nitrogen containing compounds in its hemolymph and 2-isopropyl-3-methoxypyrazine (IPMP) and mainly 2-sec-buthyl-3-methoxypyrazine
(SBMP) in higher amounts. The compound IPMP was detected as the main odor-active compound in both ladybird beetle species.
Wines infested with hemolymph of C. septempunctata were more readily detected as altered wine with a ‘ladybird taint’ than wines infested with H. axyridis. 2-isobuthyl-3-methoxypyrazine (IBMP) could be identified as second intensive odor-active compound of C. septempunctata, which occurred in a much lower frequency in H. axyridis. SBMP, the second highest measured N-compound of H. axyridis, had a lower olfactory active threshold in gas chromatography–olfactometry test. C. septempunctata contained less SBMP in its hemolymph than H. axyridis. This study objected that besides H. axyridis also C. septempunctata can influence the taste of wine in a detectable way. 相似文献
993.
Denis Schütz Marco Deluca Werner Krauss Antonio Feteira Tim Jackson Klaus Reichmann 《Advanced functional materials》2012,22(11):2285-2294
Bismuth sodium titanate (BNT)‐derived materials have seen a flurry of research interest in recent years because of the existence of extended strain under applied electric fields, surpassing that of lead zirconate titanate (PZT), the most commonly used piezoelectric. The underlying physical and chemical mechanisms responsible for such extraordinary strain levels in BNT are still poorly understood, as is the nature of the successive phase transitions. A comprehensive explanation is proposed here, combining the short‐range chemical and structural sensitivity of in situ Raman spectroscopy (under an applied electric field and temperature) with macroscopic electrical measurements. The results presented clarify the causes for the extended strain, as well as the peculiar temperature‐dependent properties encountered in this system. The underlying cause is determined to be mediated by the complex‐like bonding of the octahedra at the center of the perovskite: a loss of hybridization of the 6s2 bismuth lone pair interacting with the oxygen p‐orbitals occurs, which triggers both the field‐induced phase transition and the loss of macroscopic ferroelectric order at the depolarization temperature. 相似文献
994.
Jackson LS Beacham-Bowden T Keller SE Adhikari C Taylor KT Chirtel SJ Merker RI 《Journal of food protection》2003,66(4):618-624
Patulin is a mycotoxin produced primarily by Penicillium expansum, a mold responsible for rot in apples and other fruits. The growth of this fungus and the production of patulin are common in fruit that has been damaged. However, patulin can be detected in visibly sound fruit. The purpose of this project was to determine how apple quality, storage, and washing treatments affect patulin levels in apple cider. Patulin was not detected in cider pressed from fresh tree-picked apples (seven cultivars) but was found at levels of 40.2 to 374 microg/liter in cider pressed from four cultivars of fresh ground-harvested (dropped) apples. Patulin was not detected in cider pressed from culled tree-picked apples stored for 4 to 6 weeks at 0 to 2 degrees C but was found at levels of 0.97 to 64.0 microg/liter in cider pressed from unculled fruit stored under the same conditions. Cider from controlled-atmosphere-stored apples that were culled before pressing contained 0 to 15.1 microg of patulin per liter, while cider made from unculled fruit contained 59.9 to 120.5 microg of patulin per liter. The washing of ground-harvested apples before pressing reduced patulin levels in cider by 10 to 100%, depending on the initial patulin levels and the type of wash solution used. These results indicate that patulin is a good indicator of the quality of the apples used to manufacture cider. The avoidance of ground-harvested apples and the careful culling of apples before pressing are good methods for reducing patulin levels in cider. 相似文献
995.
Klaus Gassenmeier Peter Schieberle 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1995,201(3):241-248
The most important odorants in the crumbs of wheat breads (French-type) prepared according to two different dough recipes using pre-fermentation (crumb I: liquid pre-ferment, containing 0.25% yeast and 1.5% yeast in the final dough; crumb II: soft dough pre-ferment containing 15% yeast and 4.6% yeast in the final dough) were evaluated on the basis of aroma extract dilution analyses. In crumb I, exhibiting the more typical flavour, comparatively higher flavour dilution (FD) factors were found especially for 2-phenylethanol (2-PE) and 3-methyl-butanol (3-MB), while in crumb II the FD factors of methional, 1-octen-3-one, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, butanoic acid and 2- and 3-methylbutanoic acid were higher than in crumb I. Quantitative studies (stable isotope dilution assays) of 2-PE and 3-MB formation, in the liquid pre-ferments containing low yeast concentrations (0.25%) revealed that anaerobic conditions and a fermentation temperature of 35 °C favoured the production of both odorants. Model studies, in which either the 3-MB precursors L-leucine and 3-methylbutanal or the 2-PE precursors L-phenylalanine and phenylacetaldehyde had been added to the pre-ferments, indicated that bakers yeast significantly (15–55%) converted these precursors into the respective odorant.
Intensive Aromastoffe in der Krume von Weißbrot (französische Art)-Einfluß von Vorteigen und Studien zur Bildung wichtiger Geruchsstoffe im Verlauf der Teigherstellung
Zusammenfassung Die wichtigsten Geruchsstoffe in den Krumen von Weißbroten (französische Art), die nach verschiedenen Rezepturen aus vorfermentiertem Teig hergestellt worden waren (Krume I: flüssiger Vorteig mit 0,25% Bäckerhefe und 1,5% Hefe im backfertigem Teig; Krume II: weicher Vorteig mit 15% Hefe und 4,6% Hefe im backfertigen Teig) wurden anhand von Aromaextraktverdün-nungsanalysen bewertet. In Krume I, die das typischere Aroma aufwies, zeigten insbesondere 2-Phenylethanol und 3-Methylbutanol vergleichsweise höhere FD-Faktoren, während in Krume II die FD-Faktoren von Methional, 1-Octen-3-on, 4-Hydroxy-2,5-dimethyl-3(2H)-furanon, Buttersäure sowie 2- und 3-Methylbuttersäure höher waren als in Krume I. Quantitative Untersuchungen (Isotopenver-dünnungsanalysen) zur Freisetzung von 2-Phenylethanol (2-PE) und 3-Methylbutanol (3-MB) in flüssigen Vorteigen mit niedrigen Hefekonzentrationen (0,25%) zeigten, daß anaerobe Bedingungen sowie eine Fermentationstemperatur von 35 °C die Aromastoffbildung begünstigen. Modellstudien, in denen Vorteige zum einen mit L-Leucin und 3-Methylbutanal als Vorläufer von 3-MB, zum anderen mit L-Phenylalanin und Phenylacetaldehyd als Vorläufer des 2-PE angereichert worden waren, ergaben, daß Bäckerhefe diese Vorläufer sehr effektiv (15 bis 55%) zu den Aromastoffen umsetzt.相似文献
996.
In a previous study irradiation of cowpea flours and pastes at medium (10 kGy) and high (50 kGy) doses resulted in significant changes in protein-related functional properties. To understand some of the effects of gamma irradiation on cowpea proteins in particular, we isolated proteins from cowpea flours (FPC) and pastes (PPC) treated with gamma irradiation at 2, 10, and 50 kGy and analyzed their functional, thermal and molecular properties. Nitrogen solubility index of both FPC and PPC decreased, whereas oil absorption and emulsion capacities increased significantly with increasing irradiation dose. Differential scanning calorimetry showed decreases in transition temperatures (Td) and enthalpies (ΔH), indicating a progressive denaturation of cowpea proteins with increasing irradiation. Size exclusion HPLC revealed increases in protein molecular weights, probably due to protein–protein cross-linking with irradiation in a dose-dependent manner. Reducing SDS-PAGE of FPC and PPC samples seems to suggest that the contribution of disulphide bonds to irradiation-induced cowpea protein–protein cross-linking is small. 相似文献
997.
Uwe Gröber Joachim Schmidt Klaus Kisters 《Critical reviews in food science and nutrition》2020,60(2):257-275
AbstractInteractions between drugs and micronutrients have received only little or no attention in the medical and pharmaceutical world in the past. Since more and more pharmaceutics are used for the treatment of patients, this topic is increasingly relevant. As such interactions – depending on the duration of treatment and the status of micronutrients – impact the health of the patient and the action of the drugs, physicians and pharmacists should pay more attention to such interactions in the future. This review aims to sensitize physicians and pharmacists on drug micronutrient interactions with selected examples of widely pescribed drugs that can precipitate micronutrient deficiencies. In this context, the pharmacist, as a drug expert, assumes a particular role. Like no other professional in the health care sector, he is particularly predestined and called up to respond to this task. The following article intends to point out the relevance of mutual interactions between micronutrients and various examples of widely used drugs, without claiming to be exhaustive. 相似文献
998.
Elberling B Søndergaard J Jensen LA Schmidt LB Hansen BU Asmund G Zunić TB Hollesen J Hanson S Jansson PE Friborg T 《Environmental science & technology》2007,41(7):2407-2413
Acid mine drainage (known as AMD) is a well-known environmental problem resulting from the oxidation of sulfidic mine waste. In cold regions, AMD is often considered limited by low temperatures most of the year and observed environmental impact is related to pollution generated during the warm summer period. Here we show that heat generation within an oxidizing, sulfidic, coal-mining waste-rock pile in Svalbard (78 degrees N) is high enough to keep the pile warm (roughly 5 degrees C throughout the year) despite mean annual air temperatures below -5 degrees C. Consequently, weathering processes continue year-round within the waste-rock pile. During the winter, weathering products accumulate within the pile because of a frozen outer layer on the pile and are released as a flush within 2 weeks of soil thawing in the spring. Consequently, spring runoff water contains elevated concentrations of metals. Several of these metals are taken up and accumulated in plants where they reach phytotoxic levels, including aluminum and manganese. Laboratory experiments document that uptake of Al and Mn in native plant species is highly correlated with dissolved concentrations. Therefore, future remedial actions to control the adverse environmental impacts of cold region coal-mining need to pay more attention to winter processes including AMD generation and accumulation of weathering products. 相似文献
999.
Brischke Christian Grünwald Leopold K. Bollmus Susanne 《Holz als Roh- und Werkstoff》2021,79(6):1659-1659
European Journal of Wood and Wood Products - 相似文献
1000.
Michael Prückler Susanne Siebenhandl-Ehn Silvia Apprich Stefan Höltinger Cornelia Haas Erwin Schmid Wolfgang Kneifel 《LWT》2014
Wheat, together with maize and rice, accounts to about 90% of the world's cereal production. During the milling process, wheat bran, besides other valuable compounds such as wheat germ and parts of the endosperm, remains as major by-product. Wheat bran is composed of various histological cell layers, called the pericarp, testa, hyaline and aleurone layer and its weight ratio to milled wheat is about 25%. Annually, over 650 million tons of wheat are produced in the world, of which more than 69% are used for food. The thereby accruing biomass of wheat bran can be estimated as 150 million tons, which are basically used in the feed industry. Even if numerous studies have investigated potential health benefits of consuming more whole grain foods, the addition of bran to existing food systems may confer difficulties in terms of processing, nutrition or sensory acceptance by consumers. This review will summarize state-of-the-art technological approaches such as mechanical, thermal or enzymatic treatment used to modify the functional properties of wheat bran and coincidently describe the impact on the food system. 相似文献