全文获取类型
收费全文 | 541篇 |
免费 | 40篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 177篇 |
金属工艺 | 13篇 |
机械仪表 | 19篇 |
建筑科学 | 6篇 |
矿业工程 | 1篇 |
能源动力 | 12篇 |
轻工业 | 85篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 101篇 |
一般工业技术 | 111篇 |
冶金工业 | 17篇 |
原子能技术 | 1篇 |
自动化技术 | 24篇 |
出版年
2023年 | 8篇 |
2022年 | 8篇 |
2021年 | 16篇 |
2020年 | 13篇 |
2019年 | 19篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 21篇 |
2015年 | 24篇 |
2014年 | 15篇 |
2013年 | 34篇 |
2012年 | 41篇 |
2011年 | 45篇 |
2010年 | 40篇 |
2009年 | 46篇 |
2008年 | 31篇 |
2007年 | 27篇 |
2006年 | 29篇 |
2005年 | 16篇 |
2004年 | 19篇 |
2003年 | 12篇 |
2002年 | 14篇 |
2001年 | 11篇 |
2000年 | 14篇 |
1999年 | 7篇 |
1998年 | 8篇 |
1997年 | 2篇 |
1995年 | 5篇 |
1994年 | 9篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1990年 | 4篇 |
1989年 | 7篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有581条查询结果,搜索用时 15 毫秒
21.
Kimchi is often stored for a long period of time for a diet during the winter season because it is an essential side dish for Korean meals. In this study pH, abundance of bacteria and yeasts, bacterial communities, and metabolites were monitored periodically to investigate the fermentation process of kimchi for 120 d. Bacterial abundance increased quickly with a pH decrease after an initial pH increase during the early fermentation period. After 20 d, pH values became relatively stable and free sugars were maintained at relatively constant levels, indicating that kimchi fermentation by lactic acid bacteria (LAB) was almost completed. After that time, a decrease in bacterial abundance and a growth in Saccharomyces occurred concurrently with increased free sugar consumption and production of glycerol and ethanol. Finally, after 100 d, the growth of Candida was observed. Community analysis using pyrosequencing revealed that diverse LAB including Leuconostoc citreum, Leuconostoc holzapfelii, Lactococcus lactis, and Weissella soli were present during the early fermentation period, but the LAB community was quickly replaced with Lactobacillus sakei, Leuconostoc gasicomitatum, and Weissella koreensis as the fermentation progressed. Metabolite analysis using 1H‐NMR showed that organic acids (lactate, acetate, and succinate) as well as bioactive substances (mannitol and gamma‐aminobutyric acid (GABA)) were produced during the kimchi fermentation, and Leuconostoc strains and Lactobacillus sakei were identified as the producers of mannitol and GABA, respectively. Practical Application In this study, we have shown that the growth inhibition of yeasts including Saccharomyces and Candida is necessary to extend the shelf life of kimchi in long‐term storage. Additionally, we have shown that a mixed culture of Leuconostoc strains and Lactobacillus sakei is necessary to produce kimchi that contains both mannitol and gamma‐aminobutyric acid. 相似文献
22.
23.
Ji Hye JeonHang Ken Lee Dong Hwan WangSoon Mi Park Jeong Won KimKyung Joong Kim Jong Hyeok Park O Ok Park 《Solar Energy Materials & Solar Cells》2011,95(8):2443-2447
We present the effects of a concentration graded Li:Al cathode when it is made by one-step evaporation method using single alloy sources on the performance of organic solar cells. The concentration profile of the Li:Al cathode and related interface energy levels were investigated by means of secondary ion mass spectroscopy and ultraviolet photoelectron spectroscopy, in comparison with those of a common Al cathode. The results indicate that interfacial lithium accumulation introduces a cascade decrease of the work function (WF) of the cathode. The WF graded cathode applied to bulk heterojunction solar cells resulted in increased short circuit current and power conversion efficiency. Furthermore, the Li:Al cathode avoids the formation of interface Al-C complex, which may cause disruption of electron transport. 相似文献
24.
Che Denis Nchang Kang Hyun Ju Cho Byoung Ok Shin Jae Young Jang Seon Il 《Food science and biotechnology》2019,28(4):1207-1215
Food Science and Biotechnology - The aim of this study was to investigate the combined effects of Diospyros lotus leaves extracts (DLE) and Muscat Bailey A grape stalk extracts (MGSE) in obesity... 相似文献
25.
Potassium ion batteries (PIBs) are promising alternatives to Li‐ion batteries due to the abundance of potassium. However, the development of PIBs is in its early stages, and only a few anode materials have been reported. Herein, we explored anode materials for PIBs using high‐throughput computational screening. The alloying and conversion reactions of prospective anode materials were investigated using the Materials Project database. Grand potential diagrams were obtained to examine the reaction potential and theoretical capacity of the anode materials. Calculation results indicated that P, As, Si, and Sb anodes exhibited high theoretical capacities. In addition, the screening results revealed that phosphides generally exhibit a lower reaction potential compared with those of sulfides and oxides. A total of 18 binary compounds that exhibited a high theoretical capacity and a low reaction potential (greater than 450 mAh/g and 0.7 V) were identified as promising anode materials for PIBs. In particular, ZnP2, CuP2, SiP, NiP3, CoP3, V3S4, Nb3S5, Bi2O3, and Ga2O3 exhibited high theoretical capacities. 相似文献
26.
27.
Esra Evrim Yalçınkaya Füsun Okçu Pelit İmran Güney Hayati Türkmen 《Journal of Porous Materials》2014,21(6):1151-1158
In this study, the preparation and characterization of ionic liquid (IL) intercalated montmorillonite (MMT) and their application as a micro-solid phase extraction material for the determination of Chlorpyrifos (CP) pesticide in water samples were reported. The ionic liquids bearing different chain lengths [1-methyl-3-octylimidazolium bromide (C8mimBr), 1-methyl-3-undecyl-imidazolium bromide (C12mimBr) and 1-methyl-3-octadecyl-imidazolium bromide (C18mimBr)] were intercalated in the galleries of MMT. The IL-intercalated MMTs were characterized by means of XRD and TG methods. The (C12mimBr)-intercalated MMT had the highest sorption efficiency for the CP, which was 32 times higher than the original MMT. We also optimized the parameters for extracting CP from the (C12mimBr)-intercalated MMT. 相似文献
28.
Yong Ok Jeong 《Chemical engineering science》2003,58(7):1095-1102
A reverse-flow chromatographic reactor (RFCR) is a packed reactor in which the flow direction is reversed periodically and in which one of the reactants is strongly adsorbed on the catalyst. We study the performance of a RFCR used to destruct a pollutant A by a reaction with a reactant B, the emission level of which is subject to even stricter restrictions. Due to safety considerations, this reactant B is introduced in the center of the reactor. The RFCR operation enables a reduction of the regulated effluent products well below the minimum attainable under a steady-state operation of the same packed-bed reactor. Moreover, it can respond effectively to any perturbations in the pollutant feed rate and/or concentration. When the environmental regulations on the emission of B are stricter than those of A, it is often advantageous to feed slightly less B than the amount needed for complete conversion of A. We present a methodology for finding the operating conditions that lead to the minimal level of weighted emission of both A and B. A continuous feed of the reactant B is superior to operation in which the same amount of B is fed during each semi-cycle but in a non-continuous fashion. 相似文献
29.
Hybrid biocomposites are one of the emerging fields in polymer composites. The purpose of this study is the development and characterization of ceramic sheet (CS) hybrid polypropylene (PP) biocomposites for broadening of the field of potential applications of biocomposites. Hybrid PP biocomposites were manufactured with 20 wt % loadings of kenaf and the addition of a CS (single or double sided) by melting and compression molding. The effects of the CS on the mechanical and thermal properties of the hybrid PP biocomposites were analyzed in terms of tensile, flexural, and impact properties, and inflammability, smoke optical density, and toxicity of the combustion gas. Also, the surface morphology of fractured hybrid PP biocomposites was observed by SEM and AFM. In spite of the brittle properties of the ceramic, the mechanical properties of the hybrid PP biocomposites were improved and, also, the inflammability of the hybrid PP biocomposites with the CS was highly improved. As a result, full impregnation of CSs into the kenaf reinforced biocomposite can contribute to the improvement of both the mechanical properties and the inflammability of biocomposites, resulting in a broadening of the field of potential applications of biocomposites such as aerospace. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1917–1922, 2013 相似文献
30.
Seok Joo Park Ho Kyung Choi Young Ok Park Jae Ek Son 《Aerosol science and technology》2013,47(9):685-693
A shroud tube was used to decrease the amount of particles toward the bag filters from whole particles entering a filter vessel. The effects of the shroud tube on the flow field and particle behavior inside the vessel were studied. The air mixed with dust particles enters the vessel through a tangential inlet duct. Some of the particles are deposited on the inside wall of the vessel and the surface of the shroud tube. The other ones are collected on the filter surface or passed through it. The particles deposited on the wall surfaces fall into a hopper by gravity, and those collected on filters are removed by back pulse-jet flow. Computational simulation was performed to know the prereduction rate of particles by deposition on the wall surfaces for the different shroud tubes. The experiment was accomplished with some shroud tubes suggested by the results of computational simulation, and the experimental results were compared qualitatively with the computational results. The shroud tube blocked the direct transport of particles toward the bag filters and reduced the particle loading onto the filters. The particle loading was reduced when the upper region of the vessel was not blocked by the shroud tube more than when the vessel was blocked wholly with the filters from the upper end wall. However, the re-entrainment of the particles removed from the filters by the back pulse cleaning increased when the upper region of the vessel was not blocked by the shroud tube more than when the vessel was blocked wholly with the filters from the upper end wall. 相似文献