首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   733篇
  免费   93篇
  国内免费   1篇
综合类   5篇
化学工业   59篇
金属工艺   1篇
机械仪表   1篇
能源动力   1篇
轻工业   753篇
石油天然气   1篇
一般工业技术   5篇
冶金工业   1篇
  2024年   13篇
  2023年   21篇
  2022年   32篇
  2021年   41篇
  2020年   35篇
  2019年   51篇
  2018年   65篇
  2017年   48篇
  2016年   55篇
  2015年   44篇
  2014年   52篇
  2013年   47篇
  2012年   62篇
  2011年   61篇
  2010年   17篇
  2009年   23篇
  2008年   21篇
  2007年   16篇
  2006年   21篇
  2005年   13篇
  2004年   14篇
  2003年   9篇
  2002年   13篇
  2001年   5篇
  2000年   4篇
  1999年   5篇
  1998年   6篇
  1997年   4篇
  1996年   10篇
  1995年   4篇
  1994年   3篇
  1993年   1篇
  1992年   7篇
  1988年   1篇
  1980年   3篇
排序方式: 共有827条查询结果,搜索用时 0 毫秒
1.
Extraction of Anthocyanin Pigments from Purple Sunflower Hulls   总被引:2,自引:0,他引:2  
The anthocyanin pigments in hulls of purple sunflower seeds were extracted using three solvent systems, 50:1:49 ethanol-acetic acid-water (EAW), 0.01M acetic acid (AAc), or water containing SO2. Solvent, extraction time, size of ground hulls, pH of extracting solvent, hulls/solvent ratio, and concentration of SO2 in water, were investigated. All were significant factors affecting yield of extracted anthocyanins. EAW and SO2 were more effective extractants than AAc. Optimum conditions from response surface optimization for the extraction with sulphurous water were: SO2 at 200 mg/L, hull size 20 mesh, extraction time 5 min at 22°C, and solvent/hulls ratio = 20.  相似文献   
2.
The colour stability of juice and purées made from a mixture of two strawberry varieties, stored at + 20°C or at –20°C under aerobic and anaerobic conditions, was studied. High-performance liquid chromatography and spectrophotometric analysis were used to monitor the changes in colour during storage. Pelargonidin 3-glucoside comprised 80% of the total anthocyanin content. Four other pelargonidin-based peaks were found, being 10.4%, 3.5%, 0.7% and 0.3% of the total and two cyanidin peaks were present, being 3.3% and 0.4% of the total. Clarification before storage caused considerable losses in the initial anthocyanin concentrations. Storage conditions (air versus nitrogen) did not influence the rate of loss of anthocyanins during storage or the formation of polymeric pigments. There were no losses in anthocyanins and no increase in the amount of colour measured at 510 nm due to polymers in samples stored at–20°C. Polymerisation occurred in the samples stored at + 20°C, especially in the clarified samples.  相似文献   
3.
Supplementation with anthocyanins, which are a type of flavonoids mainly found in various berries, is hypothesized to be a promising approach to lower the risk of developing cognitive decline. The aim of this systematic review was to provide a comprehensive overview of dietary intervention trials describing effects of berry anthocyanins on cognitive performance in humans, while also addressing potential underlying mechanisms. A total of 1197 articles were identified through a systematic search, and 49 studies reporting effects on cognitive performance (n = 18), vascular function (n = 22), or cardiometabolic risk markers (n = 32) were included. Significant improvements were observed on memory, while some of the studies also reported effects on attention and psychomotor speed or executive function. Vascular function markers such as brachial artery flow-mediated vasodilation were also affected and consistent evidence was provided for the beneficial effects of berry anthocyanins on endothelial function. Finally, studies reported improvements in blood pressure, but effects on metabolic risk markers (e.g. carbohydrate and lipid metabolism) were less consistent. In conclusion, this review provides evidence for the beneficial effects of berry anthocyanins on cognitive performance as memory improved. Whether observed anthocyanin-induced improvements in vascular function and blood pressure underlie beneficial effects on cognitive performance warrants further study.  相似文献   
4.
Abstract: We have previously reported that bilberry anthocyanins exhibit an anti‐pruritic effect in a mouse model of allergic contact dermatitis. It has been reported that anthocyanins are particularly sensitive to thermal treatment and are easily hydrolyzed to anthocyanidins when exposed to high temperatures. The objective of this study was to compare the anti‐pruritic effect of anthocyanin‐rich quality‐controlled bilberry extract and anthocyanidin‐rich degraded extract using a mouse model of allergic contact dermatitis. BALB/c mice with allergic contact dermatitis induced by 4 weeks of repeated application of 2,4,6‐trinitro‐1‐chlorobenzene (TNCB) were administered Bilberon‐25 orally for 4 weeks after sensitization with TNCB. The effect of Bilberon‐25 on pruritus was evaluated by measurement of scratching behavior. RBL‐2H3 mast cells were used to investigate the effect of Bilberon‐25 on degranulation in 48/80‐stimulated mast cells. Compared with nonheated Bilberon‐25, the proportion of anthocyanins in heated Bilberon‐25 decreased, and the proportion of anthocyanidins was increased in heated‐time dependent manner. Treatment with non‐heated Bilberon‐25 significantly attenuated the TNCB‐induced increase in scratching behavior, whereas treatment with 2 h‐heated Bilberon‐25 did not. Moreover, 300 μg/mL nonheated Bilberon‐25 showed significant inhibition of degranulation in RBL‐2H3 mast cells, whereas 2 h‐heated Bilberon‐25 had no effect at any concentration studied. It is assumed that the inhibitory effect of bilberry anthocyanins on pruritus might be mediated, at least in part, by its inhibitory effect on mast cell degranulation. In conclusion, the anthocyanin‐rich but not anthocyanidin‐rich bilberry extract may be a useful dietary supplement for skin diseases involving pruritic symptoms, such as chronic allergic contact dermatitis, atopic dermatitis, and rhinitis.  相似文献   
5.
桑椹果酒酒糟中原花青素提取工艺研究   总被引:2,自引:0,他引:2  
左勇  李杨  谢晖  祁峰 《中国酿造》2012,31(8):40-44
选用溶剂浸提法从桑椹果酒酒糟中提取花青素.通过单因素和响应面(BBD)试验优化提取工艺.结果表明,影响花青素提取量因素的优先次序为提取温度>固液比>提取时间,较优的提取工艺条件为提取温度80℃、提取时间150.3min、料液比1∶20.在该条件下,花色素提取量的理论预测值为1.92264mg/g,实际验证为1.894mg/g,提取得率达到理论预测值的98.5%.  相似文献   
6.
ABSTRACT: Processing of black currant juice includes crushing, heating, enzyme treatment, pressing, pasteurization, clarification, and filtration. Changes in concentration of impact aroma compounds and anthocyanins during black currant juice processing in pilot plant scale were examined. Impact compounds were identified by gas chromatography-olfactometry and quantified by dynamic headspace and gas chromatography-mass spectrometer. Anthocyanins were analyzed by the pH-differential method. Identified aroma compounds comprised volatiles like esters, terpenes, terpenoids, and ketones. The reduction of aroma compounds and anthocyanins during the process was approximately 50 to 100% and 25%, respectively. The pressing step definitely had a negative effect on the concentration of aroma compounds and anthocyanins, and the heating treatments were mainly negative as well.  相似文献   
7.
构建大豆分离蛋白-花青素共价复合纳米颗粒,以粒径、Zeta电位、自由基清除能力、光学显微镜观察为指标,对纳米颗粒和Pickering乳液进行研究。结果表明,通过添加花青素在一定程度上改变了纳米颗粒和Pickering乳液的粒径分布与Zeta电位值;对比可知,添加花青素后纳米颗粒和乳液体系更加稳定。此外,当花青素添加量为0.15%时,纳米颗粒的粒径分布较为均一,粒径相对体积最大;纳米颗粒Zeta电位绝对值最大;自由基清除能力相对较强;并且以0.15%花青素添加量的纳米颗粒制备的Pickering乳液液滴分布较为均匀,不易发生聚集,较为稳定。  相似文献   
8.
9.
对玫瑰茄花色苷纯化工艺进行优化研究,通过对X-5、DA-201、HPD-100、D101、AB-8五种大孔树脂进行筛选,得出最适用于玫瑰茄花色苷纯化的树脂为HPD-100大孔树脂。通过单因素和正交实验对HPD-100大孔树脂纯化条件进行优化,得出最佳吸附工艺条件是:样液浓度为1.5 mg/m L,上样流速为2 m L/min,p H值为3.0,吸附率为91.988%;最佳解吸工艺条件是:洗脱液浓度为70%,洗脱流速为1.75 m L/min,洗脱液用量60 m L,解吸率为92.144%,纯化后的玫瑰茄红色素色价为38.5。通过纯化前后玫瑰茄红色素高效液相色谱图的比较可知:玫瑰茄红色素主要含有5种成分,纯化后的色素矢车菊花色苷的含量明显升高。  相似文献   
10.
Abstract: Phenolic compounds and anthocyanins in muscadines have attracted much attention due to their diverse biological activities. With bioassays of antioxidant activities in terms of total phenolic content (TPC), total anthocyanin content (TAC), total procyanidin content (TPA), oxygen radical absorbance capacity (ORAC), and ferric reducing antioxidant power (FRAP) of different parts of the Noble muscadine, the butanol (BuOH) extract of the muscadine skin showed the highest TPC (317.91 ± 1.83 mg GAE/100 g FW), which might be ascribed to its high TAC of 227.06 ± 1.29 mg/100 g fresh weight (FW). The ethyl acetate (EtOAc) extract of the muscadine seed contained the highest TPA (55.30 ± 0.63 mg CE/100 g FW). Correlation analyses demonstrated a significant linear relationship of TPC and TAC compared to their ORAC and FRAP values within the range of R2 from 0.9283 to 0.9936, which suggested that phenolics and anthocyanins in the extracts contributed significantly to their antioxidant potential. Nineteen individual phenolics and 5 anthocyanins were identified by HPLC‐MS, which indicated different chemical profiles of anthocyanins and other phenolics in the muscadine extracts. Practical Application: The paper has provided rich information of bioactive phytochemical profiles in different solvent extracts and their correlation with the antioxidant activity in the muscadine that is a very special regional fruit in U.S. Its high content of phenolic compounds demonstrates that muscadine could be beneficial to human health.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号