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51.
Hydroperoxid-Abbau durch Isomerase aus Hafer. Untersuchungen zum Reaktionsmechanismus 总被引:1,自引:0,他引:1
Werner Heimann und Verena Klaiber 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1977,165(3):140-143
Zusammenfassung Isomerase aus Hafer wird durch Hydroxyoctadecadiensduren [Monohydroxysäuren] in ähnlich starkem Maße gehemmt wie durch Linolsäurehydroperoxide [LHPO]. Hydroxysduren scheinen sich wie LHPO an das Enzym anzulagern. Durch Zusatz von (1-14C)-Hydroxysäuren bei einem LHPO-Abbau-Versuch wurde untersucht, ob die isomeratische Bildung der Epoxyhydroxysduren über einen inter-oder intramolekularen Mechanismus verläuft. Bei dem Versuch traten radioaktiv-markierte Trihydroxysduren auf—die aus den primdr gebildeten Epoxyhydroxyoctadecensduren durch Hydrolyse entstehenden Reaktionsprodukte des isomeratischen LHPO-Abbaus. Die Auswertung ergab, daß mindestens 70% der LHPO intermolekular reagiert haben.
Herrn Stadtehemiedirektor i. R. Dr. Curt Wilhelm zum 76. Geburtstag. 相似文献
Hydroperoxide degradation by oat isomerase. Investigation of the reaction mechanism
Summary Oat isomerase is inhibited by hydroxyoctadecadienoic acids (monohydroxy acids) to a degree comparable with inhibition by linoleic acid hydroperoxides (LHPO). Hydroxy acids seem to combine with the enzyme like LHPO do. In an experiment on LHPO breakdown by isomerase 1-14C-hydroxy acids were added and it was examined whether the epoxyhydroxy acids are formed by an intermolecular or intramolecular mechanism. In this experiment 1-14C-labeled trihydroxy acids were formed; they arise from the hydrolysis of epoxyhydroxyoctadecenoic acids formed on their part by isomerase effected LHPO-breakdown. It was determined that at least 70% of LHPO are converted by intermolecular reaction.
Herrn Stadtehemiedirektor i. R. Dr. Curt Wilhelm zum 76. Geburtstag. 相似文献
52.
Li Meng Verena Coleman Yu Zhao Mario Ost Anja Voigt Annelies Bunschoten Jaap Keijer Katja Teerds Susanne Klaus 《International journal of molecular sciences》2021,22(7)
In the present investigation, we examined whether a change in whole body energy fluxes could affect ovarian follicular development, employing mice ectopically expressing uncoupling protein 1 in skeletal muscle (UCP1-TG). Female UCP1-TG and wild-type (WT) mice were dissected at the age of 12 weeks. Energy intake and expenditure, activity, body weight and length, and body composition were measured. Plasma insulin, glucose, leptin, plasma fibroblast growth factor 21 (FGF21) and plasma insulin-like growth factor 1 (IGF1) levels were analyzed and ovarian follicle and corpus luteum numbers were counted. IGF1 signaling was analyzed by immunohistochemical staining for the activation of insulin receptor substrate 1/2 (IRS1/2) and AKT. UCP1-TG female mice had increased energy expenditure, reduced body size, maintained adiposity, and decreased IGF1 concentrations compared to their WT littermates, while preantral and antral follicle numbers were reduced by 40% and 60%, respectively. Corpora lutea were absent in 40% of the ovaries of UCP1-TG mice. Phospho-IRS1, phospho-AKT -Ser473 and -Thr308 immunostaining was present in the granulosa cells of antral follicles in WT ovaries, but faint to absent in the antral follicles of UCP1-TG mice. In conclusion, the reduction in circulating IGF1 levels due to the ectopic expression of UCP1 is associated with reduced immunostaining of the IRS1-PI3/AKT pathway, which may negatively affect ovarian follicle development and ovulation. 相似文献
53.
To increase the applicability of carbon nanotubes (CNTs) oxygen-containing functional groups were generated on their widely inert surface by using glow-discharge plasmas. CNT-sheets (bucky papers) produced from the powder-like raw material were used as substrates allowing for a more defined characterization of one and the same surface by different analytical techniques. The plasma composition was analyzed by optical emission spectroscopy. Since the actual composition of the plasma-induced functional groups has still not been completely resolved, we performed an in-depth characterization of the treated samples by X-ray photoelectron (XPS) and Raman spectroscopy as well as electron spin resonance measurements. To overcome limitations of the XPS-analysis in distinguishing between groups featuring nearby binding energies, alcohol-, keto-/aldehyde-, and carboxyl-groups were tagged by derivatization techniques using fluorine-containing reagents (trifluoroaceticanhydride, trifluoromethylphenylhydrazine, and trifluoroethanol). Differential spectra were calculated to enhance the accuracy of the deconvolution of the XPS-spectra. This enabled us to determine dependencies of the plasma parameters, i.e. treatment time, process pressure, and gas composition (mixtures of Ar, O2, H2O, and H2), on the composition of the generated functional groups as well as an up to 6-fold enhancement in derivatizable groups for switching process gas from Ar/O2 to Ar/H2O. 相似文献
54.
55.
Verena Wiedenmann Kathleen Oehlke Ulrike van der Schaaf Hanna M. Koivula Kirsi S. Mikkonen Heike P. Karbstein 《Journal of food science》2019,84(12):3642-3652
Protein films can be applied to improve food quality and to reduce packaging waste. To overcome their poor water barrier properties, lipids are often incorporated. The function of incorporated lipid depends on the interface between filler and matrix. This study aimed to tailor the properties of a protein–lipid film by designing the oil/water interface to see if the concept of inactive/active filler is valid. Therefore, we varied the emulsifier stabilizing solid lipid nanoparticles (SLN) to promote (via β‐lactoglobulin) or to minimize (via Tween 20) interactions between particle surface and protein. SLN were incorporated into protein films and film properties were determined. Addition of SLN led to significantly decreased water vapor permeability (WVP) of protein films. However, WVP was mainly affected by the emulsifiers and not by the lipid. Protein‐stabilized SLN (BS) replaced a lacking protein in the protein network and therefore did not influence the mechanical properties of the films at ambient temperature. BS‐composite films were temperature sensitive, as lipid and sucrose palmitate melted at temperatures above 40 °C. Tween 20‐stabilized SLN (TS) led to reduced tensile strengths, probably due to perturbative effects of TS and plasticizing effects of Tween 20. Dynamic mechanical analysis showed that TS and Tween 20 increased film mobility. Melting of lipid and emulsifiers, and temperature‐dependent behavior of Tween 20 led to a strong temperature dependence of the film stiffness. By designing the interface, particles can be used to tailor mechanical properties of protein films. Tuned edible films could be used to control mass transfers between foods. 相似文献
56.
Companies have long used various approaches for organizing their employees' time for creative and routine tasks in order to improve innovative performance. In this paper, we examine how work schedule autonomy affects individuals' creative and routine performance. We then evaluate non‐commissioned time models. Results of laboratory experiments with 233 participants reveal that while average routine performance is not affected by schedule autonomy, the effect of schedule autonomy on creative performance depends on the subject's impulsiveness. There is evidence of an inverse relationship between schedule autonomy and creative performance among subjects of low impulsiveness. Hence, our results indicate that the optimal management policy depends on the manager's focus on creative or routine performance and the types of employees the manager supervises. For routine performance, the creativity time model has no significant impact. 相似文献
57.
Guo‐Feng Luo Yonatan Biniuri Margarita Vzquez‐Gonzlez Verena Wulf Michael Fadeev Ronit Lavi Itamar Willner 《Advanced functional materials》2019,29(33)
A series of metal ion‐terpyridine‐modified L‐tyrosinamide aptamers (Mn + = Cu2+ or Fe3+) act as enzyme‐mimicking catalysts (nucleoapzymes) for oxygen‐insertion into C? H bonds and the transformation of L‐tyrosinamide into amidodopachrome. The reaction proceeds in the presence of H2O2 and coadded L‐ascorbic acid. In one series of experiments, the catalyzed oxidation of L‐tyrosinamide to amidodopachrome by a set of nucleoapzymes consisting of Fe3+‐ or Cu2+‐terpyridine complexes tethered directly or through a 4 × thymidine (4 × T) bridge, to the 5′‐ or 3′‐end of the 49‐mer L‐tyrosinamide aptamer or to a shorter 23‐mer L‐tyrosinamide aptamer is examined. All nucleoapzymes reveal catalytic Michaelis–Menten enzyme‐like activities and the separated Fe3+‐ or Cu2+‐terpyridine and L‐tyrosinamide aptamer units show only minute catalytic properties. The catalytic activities of the nucleoapzymes are attributed to the concentration of the L‐tyrosinamide substrate by the aptamer units in proximity to the catalytic sites (Kd = (14 ± 0.1) × 10?6 m for all 49‐mer catalysts and Kd = (2.5 ± 0.1) × 10?6 m and Kd = (0.8 ± 0.04) × 10?6 m for the 23‐mer catalysts). Electron spin resonance experiments reveal that ?OH radicals and ascorbate radicals participate in the transformation of tyrosine derivatives to catechol products. An autocatalytic feedback mechanism for the amplified generation of the two radicals is suggested. 相似文献
58.
Effect of different biopolymers and polymers on the mechanical and permeation properties of extruded PHBV cast films 下载免费PDF全文
The biopolymer poly‐3‐hydroxybutyrate‐co‐3‐hydroxyvalerate (PHBV) is a promising material for packaging applications but its high brittleness is challenging. To address this issue, PHBV was blended with nine different biopolymers and polymers in order to improve the processing and mechanical properties of the films. Those biopolymers were TPS, PBAT, a blend of PBAT + PLA, a blend of PBAT + PLA + filler, PCL and PBS, and the polymers TPU, PVAc, and EVA. The extruded cast films were analyzed in detail (melting temperature, crystallinity, mechanical properties, permeation properties, and surface topography). A decrease in crystallinity and Young's modulus and an increase in elongation at break and permeability were observed with increasing biopolymer/polymer concentration. In PHBV‐rich blends (≥70 wt % PHBV), the biopolymers/polymers PCL, PBAT, and TPU increased the elongation at break while only slightly increasing the permeability. Larger increases in the permeability were found for the films with PBS, PVAc, and EVA. The films of biopolymer/polymer‐rich blends (with PBAT, TPU, and EVA) had significantly different properties than pure PHBV. A strong effect on the properties was measured assuming that at certain biopolymer/polymer concentrations the coherent PHBV network is disrupted. The interpretation of the permeation values by the Maxwell–Garnett theory confirms the assumption of a phase separation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46153. 相似文献
59.
Production,nutrient cycling and soil compaction to grazing of grass companion cropping with corn and soybean 总被引:1,自引:0,他引:1
Cristiano M. Pariz Ciniro Costa Carlos A. C. Crusciol Paulo R. L. Meirelles André M. Castilhos Marcelo Andreotti Nídia R. Costa Jorge M. Martello Daniel M. Souza Verena M. Protes Vanessa Z. Longhini Alan J. Franzluebbers 《Nutrient Cycling in Agroecosystems》2017,108(1):35-54
Agricultural management systems are needed to simultaneously enhance production, promote plant diversity, improve nutrient cycling and reduce soil compaction. We investigated the effects of intercropped forage grass on production of corn (Zea mays L.) harvested for silage at 0.20 and 0.45 m height in the summer, as well as on production of subsequent forage, soybean [Glycine max (L.) Merr.] harvested for silage, nutrient cycling and soil responses on a Typic Haplorthox in Botucatu, São Paulo State, Brazil. Palisade grass cv. BRS Piatã [Urochloa brizantha cv. BRS Piatã] was the introduced companion crop with corn (Years 1 and 2), while signal grass [Urochloa decumbens cv. Basilisk] was the residual weedy species in comparison. Guineagrass cv. Aruãna [Megathyrsus maximus cv. Aruãna] was the introduced companion crop with soybean (Year 3), with only a residual effect of crop systems from the previous two years. After the corn silage harvest, pasture was grazed by lambs in winter/spring using a semi-feedlot system. When cut at 0.45 m compared with 0.20 m height, corn intercropped with palisade grass had greater leaf nutrient concentration, improved agronomic characteristics, forage mass of pasture for grazing by lambs, greater surface mulch produced, and greater quantity of N, P and K returned to soil. Greater soil organic matter, P, K and Mg concentration, and base saturation in the surface soil depth and lower soil penetration resistance at all depths occurred at 0.45 m than at 0.20 m corn silage cutting height intercropped with palisade grass. Analyzing the system as a whole, harvesting corn silage crop with palisade grass intercrop at 0.45 m height was the most viable option in this integrated crop-livestock system. 相似文献
60.
Verena Ruhlmann Philipp Heusch Hilmar Kühl Karsten Beiderwellen Gerald Antoch Michael Forsting Andreas Bockisch Christian Buchbender Harald H. Quick 《Magma (New York, N.Y.)》2016,29(2):301-308