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991.
Comparison and Characterization of Compounds with Antioxidant Activity in Lycium barbarum Using High‐Performance Thin Layer Chromatography Coupled with DPPH Bioautography and Tandem Mass Spectrometry
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Shing‐Chung Lam Zhen Luo Ding‐Tao Wu Kit‐Leong Cheong De‐Jun Hu Zu‐Meng Xia Jing Zhao Shao‐Ping Li 《Journal of food science》2016,81(6):C1378-C1384
Methanol extracts from 50 batches of Lycium barbarum (L. barbarum, wolfberry) in China were compared and characterized using high‐performance thin‐layer chromatography coupled with 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) bioautography (HPTLC‐DPPH) and electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry (ESI‐Q‐TOF‐MS/MS), respectively. Results showed that similar components occupying the major antioxidant activity existed in L. barbarum collected from different origins. However, the average antioxidant capacities of methanol extracts of L. barbarum collected in Ningxia were significantly higher than those of Qinghai, Xinjiang, Inner Mongolia, and Gansu, which may contribute to rational use of L. barbarum in China. Furthermore, the chemical structure of compound with the highest antioxidant capacity was tentatively identified as 2‐O‐β‐d ‐glucopyranosyl‐l ‐ascorbic acid using ESI‐Q‐TOF‐MS/MS analysis, which possessed high potentials to be used as an antioxidant biomarker for the quality control of L. barbarum. Results are helpful for the bioactivity‐based quality control of L. barbarum, and beneficial for the improvement of their performance in functional/health foods area, suggesting that HPTLC‐DPPH bioautography with ESI‐Q‐TOF‐MS/MS could be used as a routine approach for quality control of antioxidant components in L. barbarum. 相似文献
992.
DNA barcoding as a new tool for food traceability 总被引:1,自引:0,他引:1
Andrea Galimberti Fabrizio De Mattia Alessia Losa Ilaria Bruni Silvia Federici Maurizio Casiraghi Stefano Martellos Massimo Labra 《Food research international (Ottawa, Ont.)》2013,50(1):55-63
Food safety and quality are nowadays a major concern. Any case of food alteration, especially when reported by the media, has a great impact on public opinion. There is an increasing demand for the improvement of quality controls, hence addressing scientific research towards the development of reliable molecular tools for food analysis. DNA barcoding is a widely used molecular-based system, which can identify biological specimens, and is used for the identification of both raw materials and processed food. In this review the results of several researches are critically analyzed, in order to exploit the effectiveness of DNA barcoding in food traceability, and to delineate some best practices in the application of DNA barcoding throughout the industrial pipeline. The use of DNA barcoding for food safety and in the identification of commercial fraud is also discussed. 相似文献
993.
994.
拉曼光谱特别是表面增强拉曼光谱(surface enhanced Raman scattering, SERS)是一种基于光的非弹性散射的光谱技术,具有实时、快速等特点,是一种很好的检测茶叶质量安全和品质分析的方法。本文介绍了拉曼光谱及SERS技术在茶叶农药残留、重金属和真菌毒素等质量安全检测方面的应用,以及在茶叶理化成分检测和茶叶种类分析等茶叶品质分析上的研究进展。 相似文献
995.
996.
Chain interactions of sodium alginate during its gelation were investigated by a new gelation method which was based on a Ca2+-concentrating gelling process (CCGP) produced by water evaporation of an alginate solution containing CaCl2. For two commercially available sodium alginate samples (low viscosity (LA) and medium viscosity (MA)) having different molecular weight distributions but the same G/M blocks, the critical Ca2+ concentrations for their gelation were found to be 4.6 (for LA) and 4.5 (for MA) μmol/mL after evaporating water from 1% of alginate solutions containing 4 μmol/mL of CaCl2. The CCGP gelation method for alginate under the above conditions were confirmed by rheological measurements and the observed highly ordered and uniform mesh structure of the CCGP-formed alginate gels shown in cryo-SEM images. Combinations of LA and MA at different ratios (0:4, 1:3, 2:2, 3:1, 4:0 on weight basis) were studied using the CCGP gelation method to further the understanding of the alginate chain interactions during gelation. Different LA/MA mixtures exhibited different rheological properties in either non-gelled or gelled systems, indicating that the molecular weight distributions of the sodium alginates influence the alginate chain interactions mediated by Ca2+. Thus, an appropriate combination of LA and MA is required for a strong alginate interchain interaction during CCGP, and alginate products with desirable characteristics can be produced by manipulating the mixing ratios of sodium alginates having different molecular weight distributions even at the same total composition and distribution of G/M blocks. 相似文献
997.
De Kwaadsteniet M Todorov SD Knoetze H Dicks LM 《International journal of food microbiology》2005,105(3):433-444
Strain ST15, isolated from soy beans, and identified as Enterococcus mundtii, produces a 3944 Da bacteriocin that inhibits the growth of Lactobacillus sakei, Enterococcus faecalis, Bacillus cereus, Propionibacterium sp., Clostridium tyrobutyricum, Acinetobacter baumanii, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pneumoniae and Streptococcus caprinus. Bacteriocin ST15 is inactivated by proteinase K, pronase, pepsin, protease and Triton X-114, but not when treated with catalase, alpha-amylase, Triton X-100, SDS, Tween 20, Tween 80, urea and EDTA. No change in activity was recorded after 2 h at pH values between 2.0 and 12.0, and after treatment at 100 degrees C for 90 min. Activity was, however, lost after treatment at 121 degrees C for 20 min. The mode of activity is bactericidal. The highest level of activity (51200 AU ml(-1)) was recorded when cells were grown in MRS broth, pH 6.5. Bacteriocin ST15 differs from other broad-spectrum bacteriocins described for Enterococcus spp. by being active against Gram-negative bacteria and by being smaller. 相似文献
998.
Rasschaert G Michiels J Arijs D Wildemauwe C De Smet S Heyndrickx M 《Journal of food protection》2012,75(5):859-866
Salmonella represents a major challenge to the pig industry, as pork presents a risk for human salmonellosis. In this study, we have examined the effect of farm type on the prevalence of fattening pigs shedding Salmonella on 12 farms at risk for harboring Salmonella. On six open (grow-to-finish) and six closed (farrow-to-finish) farms, the prevalence of pigs shedding Salmonella was determined on two occasions approximately 2 months apart. The serovar, phage type, and antimicrobial resistance of the obtained Salmonella isolates were determined. On all farms, pigs shedding Salmonella were detected on at least one of the two sampling days. The mean within-herd prevalence was 7.8%. Closed farms were two times less likely to have pigs shedding Salmonella than open farms. On open farms, the odds of finding Salmonella shedding in pigs were 1.9 times higher when sampling was performed at slaughter age than when samples were taken halfway through the fattening period. Salmonella enterica serovar Typhimurium was the most predominant serotype, with a prevalence of 62 to 63% on both farm types. Of all the Salmonella Typhimurium isolates, 65% had the tetraresistant profile ASSuT (ampicillin, streptomycin, sulfonamide, and tetracycline) with or without additional resistance to trimethoprim-sulfonamide. Phage type DT120 seemed to be especially associated with this antimicrobial-resistant profile. The prevalence of Salmonella Typhimurium isolates showing resistance to ampicillin, streptomycin, tetracycline, sulfonamide, trimethoprim-sulfonamide, and lincomycin hydrochloride and spectinomycin sulfate tetrahydrate was significantly higher on open farms than on closed farms. 相似文献
999.
Extrusion of Rice,Bean and Corn Starches: Extrudate Structure and Molecular Changes in Amylose and Amylopectin 总被引:1,自引:0,他引:1
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Nathan Levien Vanier Varatharajan Vamadevan Graziella Pinheiro Bruni Cristiano Dietrich Ferreira Vânia Zanella Pinto Koushik Seetharaman Elessandra da Rosa Zavareze Moacir Cardoso Elias Jose De J. Berrios 《Journal of food science》2016,81(12):E2932-E2938
The objective of this study was to evaluate the effects of starch source and amylose content on the expansion ratio, density, and texture of expanded extrudates, as well as to investigate the structural and molecular changes that occur in starch granules as a function of extrusion. The starches employed were rice starches (8%, 20%, and 32% amylose), carioca bean starch (35% amylose), and Hylon V® corn starch (55% amylose). The extrudates from rice starches containing 20% and 32% amylose exhibited the highest expansion ratio, while, extrudates from Hylon V® corn starch containing 55% amylose exhibited the lowest expansion ratio. The hardness values of the extrudates with 55% amylose were twice those of the extrudates with 20%, 32%, and 35% amylose. An additional finding was that although the amylopectin promoted the expansion of the gelatinized starch matrix, it failed to strengthen and sustain the walls of the extrudate bubbles during expansion. 相似文献
1000.