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《Sensors and actuators. B, Chemical》2006,113(1):106-111
A stable film made from hydroxyethylcellulose (HEC) on pyrolytic graphite (PG) electrode was employed for incorporating hemoglobin (Hb), myoglobin (Mb) and horseradish peroxidase (HRP), and the electrochemical characteristics of the proteins were studied correspondingly. Experimental results revealed that HEC film could greatly accelerate electron transfer between the proteins and electrode, and the proteins showed a thin layer electrochemical behavior in the film. Moreover, all the proteins in the film exhibited good catalytic activity towards the reduction of hydrogen peroxide (H2O2) in the low H2O2 concentration range. In the high concentration range, H2O2 would exhibit toxicity effect on the proteins. The electrochemical properties and electrocatalytic abilities of the three heme proteins in HEC film have been compared, and the optimal conditions for H2O2 biosensor fabrication have been obtained. 相似文献
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《Catalysis communications》2007,8(11):1834-1837
Benzophenone and its derivatives were prepared via Friedel–Crafts acylation reactions using ionic liquids (ILs) of BmimCl–FeCl3, BmimCl–AlCl3 and BmimCl–ZnCl2 as dual catalyst–solvent. Among them, BmimCl–FeCl3 showed much higher catalytic activity than that observed for the other two ILs, and in conventional organic solvents. In these reaction systems, good to excellent yields (up to 97%) of acylation products were obtained in a short reaction time. This method features high yield, a simple product isolation procedure, ILs reusability and reduced waste discharge, thus rendering this catalytic system both efficient and environmentally friendly. 相似文献
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目的 对微酸性电解水在水产品保鲜加工中的应用研究进展进行总结,为后续研究提供理论参考。方法 在介绍微酸性电解水制备原理与作用机制的基础上,围绕该技术在水产品保鲜加工中的应用研究进展予以阐述,提出存在问题与解决办法。结果 水产品经微酸性电解水处理后,可明显抑制水产品中的微生物生长,延缓pH值升高,改善保水性能,保持产品色泽,提升质构特性。然而,随着消费者对水产品品质要求的不断提高,仅使用微酸性电解水处理并非理想的方式,可结合其他理化与生物保鲜技术,以提升微酸性电解水的综合作用效果。结论 微酸性电解水在水产品保鲜加工中占有一定优势,且能结合其他处理方式提升其在水产品杀菌保鲜与品质保持等方面的加工效率。 相似文献
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《Food Control》2014
Shelf-life of commercial thawed tuna was studied in different packaging atmospheres: Air, High O2 (70%O2/30%CO2), Sprayed green tea extract in High O2, Low O2 (40%O2/40%CO2/20%N2), Non O2 (60%CO2/40%N2) and Carbon monoxide (60%CO2/39.5%N2/0.5%CO). Three-cm-wide slices were analysed at days 0 (24 h post-thawing), 4 and 6 from the date of packaging while kept in retail conditions. Analysis performed each day of the study were: gas concentration in the headspace, colour, pH, exudative losses, lipid oxidation, total volatile bases nitrogen, microbiological analysis and a sensory test (fresh and cooked fish). The atmospheres ‘Non O2’ and ‘Low O2’ were the most effective for increasing tuna shelf-life due to better general lipid oxidation characteristics, microbial counts and sensory results. Shelf-life reached up to 6 days post-thawing in these cases although tuna should be consumed cooked to prevent risk of pathogens or toxins. Also, the use of antioxidants or carbon monoxide improved colour and flavour attributes and should be considered as alternatives for packaging. 相似文献
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This study was conducted to investigate the effects of different tempering methods and freeze-thaw cycles on melanosis and quality parameters of pacific white shrimp. Frozen pacific white shrimps tempered with radio frequency tempering (RFT) were compared to that in water tempering (WT) and refrigerator tempering (RT) in terms of temper loss, total volatile base nitrogen (TVBN), polyphenol oxidase (PPO) activity, melanosis, total sulfhydryl contents, differential scanning calorimetry (DSC), and texture properties after 0, 1, 3, 5 freeze-thaw cycles. Results showed that crushed ice was effective as an effective surrounding medium for six layers of frozen shrimp reaching −2 °C within 6 min in RFT. For quality attributes, the temper loss of samples tempered with radio frequency is lower than that of RT and WT after all freeze-thaw cycles, and RFT resulted in the lowest TVBN value (9.17 mgN/100 g) of shrimps after the 5th freeze-thaw cycle. The PPO activity and melanosis of samples increased as the number of freeze-thaw cycles increased, and RFT effectively inhibited the development of melanosis. After the 3rd freeze-thaw cycle, the enthalpy change (△H) and the sulfhydryl content (0.16 mmol/gprot) of radio frequency tempered samples was significantly higher (p < 0.05) than that of WT and RT. RFT retained the hardness and chewiness of shrimp samples in all freeze-thaw cycles. Therefore, RFT effectively inhibited melanosis and reduce protein oxidation in Pacific white shrimp during freeze-thaw cycles with its fast and uniform heating characteristics. 相似文献
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Xi Chen Guo-Ping Wu Qiu-Feng Cai Guang-Ming Liu Kiyoshi Osatomi Wen-Jin Su Min-Jie Cao 《Food chemistry》2012,130(3):679-686
An aminopeptidase was purified from Japanese flounder skeletal muscle to homogeneity by ammonium sulphate fractionation and three chromatographies. The enzyme was approximately 100 kDa with isoelectric point of 5.7 as estimated by two-dimensional polyacrylamide gel electrophoresis. Its optimum temperature and pH were 45 °C and 7.5, respectively. According to peptide mass fingerprinting study, the enzyme revealed high identity to a puromycin-sensitive aminopeptidase. It had a broad specificity toward aminopeptidase substrates and preferred to hydrolyse Lys-MCA with kcat/Km of 8.1 × 106 M?1 s?1, and the activation energy (Ea) of 72.5 kJ M?1. Metal-chelating agents effectively inhibited the enzyme activity, and Zn2+, Mn2+ and Co2+ significantly restored the apoenzymatic activity dialysed by EDTA, whilst inhibitors to other proteinases did not show much effect. Furthermore, bestatin strongly inhibited its activity. These results indicate that the purified enzyme is a metalloaminopeptidase which would possibly contribute to free amino acids increase in fish muscle. 相似文献
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