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   495篇
  免费   35篇
  国内免费   43篇
  2024年   1篇
  2023年   9篇
  2022年   8篇
  2021年   11篇
  2020年   16篇
  2019年   17篇
  2018年   13篇
  2017年   13篇
  2016年   14篇
  2015年   17篇
  2014年   13篇
  2013年   27篇
  2012年   25篇
  2011年   22篇
  2010年   20篇
  2009年   29篇
  2008年   23篇
  2007年   25篇
  2006年   24篇
  2005年   30篇
  2004年   17篇
  2003年   34篇
  2002年   14篇
  2001年   4篇
  2000年   13篇
  1999年   15篇
  1998年   12篇
  1997年   16篇
  1996年   11篇
  1995年   7篇
  1994年   20篇
  1993年   7篇
  1992年   10篇
  1991年   10篇
  1990年   1篇
  1989年   5篇
  1988年   4篇
  1987年   2篇
  1986年   2篇
  1985年   3篇
  1984年   5篇
  1983年   1篇
  1974年   1篇
  1972年   2篇
排序方式: 共有573条查询结果,搜索用时 31 毫秒
21.
The rare ginsenosides are recognized as the functionalized molecules after the oral administration of Panax ginseng and its products. The sources of rare ginsenosides are extremely limited because of low ginsenoside contents in wild plants, hindering their application in functional foods and drugs. We developed an effective combinatorial biotechnology approach including tissue culture, immobilization, and hydrolyzation methods. Rh2 and nine other rare ginsenosides were produced by methyl jasmonate-induced culture of adventitious roots in a 10 L bioreactor associated with enzymatic hydrolysis using six β-glycosidases and their combination with yields ranging from 5.54 to 32.66 mg L−1. The yield of Rh2 was furthermore increased by 7% by using immobilized BglPm and Bgp1 in optimized pH and temperature conditions, with the highest yield reaching 51.17 mg L−1 (17.06% of protopanaxadiol-type ginsenosides mixture). Our combinatorial biotechnology method provides a highly efficient approach to acquiring diverse rare ginsenosides, replacing direct extraction from Panax plants, and can also be used to supplement yeast cell factories.  相似文献   
22.
Early weaning usually causes intestinal disorders, enteritis, and diarrhea in young animals and human infants. Astragalus polysaccharides (APS) possesses anti-inflammatory activity. To study the anti-inflammatory mechanisms of APS and its potential effects on intestinal health, we performed an RNA sequencing (RNA-seq) study in lipopolysaccharide (LPS)-stimulated porcine intestinal epithelial cells (IPEC-J2) in vitro. In addition, LPS-stimulated BALB/c mice were used to study the effects of APS on intestinal inflammation in vivo. The results from the RNA-seq analysis show that there were 107, 756, and 5 differentially expressed genes in the control versus LPS, LPS versus LPS+APS, and control versus LPS+APS comparison groups, respectively. The results of Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated that the mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways play significant roles in the regulation of inflammatory factors and chemokine expression by APS. Further verification of the above two pathways by using western blot and immunofluorescence analysis revealed that the gene expression levels of the phosphorylated p38 MAPK, ERK1/2, and NF-κB p65 were inhibited by APS, while the expression of IκB-α protein was significantly increased (p < .05), indicating that APS inhibits the production of inflammatory factors and chemokines by the inhibition of activation of the MAPK and NF-κB inflammatory pathways induced by LPS stimulation. Animal experiments further demonstrated that prefeeding APS in BALB/c mice can alleviate the expression of the jejunal inflammatory factors interleukin 6 (IL-6), IL-Iβ, and tumor necrosis factor-α induced by LPS stimulation and improve jejunal villus morphology.  相似文献   
23.
24.
25.
(R)-2-(4′-Isobutylphenyl)propanoic acid (ibuprofen), (S)-3(4′-isobutylphenyl)butanoic acid and (S)-4-(4′-isobutylphenyl)pentanoic acid were obtained using microbial oxidation of (±)-l-isobutyl-4-(1′ -methyloctyl)benzene by Rhodococcus sp. BPM 1613.  相似文献   
26.
The extract of the stem bark of Siberian ginseng, Acanthopanax senticosus Harms (ASH), is believed to play a body-coping role in stress through a brain noradrenergic mechanism. The present study was carried out to investigate the effect of ASH on the neuronal activation patterns of c-Fos expression in the rat brain. With ASH administration, c-Fos accumulated in both the supraoptic nuclei (SON) and paraventricular nuclei (PVN), which regulate stress response. Only the caudal regions in the nucleus of the solitary tract (NTS), a locus innervating both the SON and PVN, were activated. Such a neuro-anatomical pattern associated with ASH suggests the possible involvement of these stress-related brain loci.  相似文献   
27.
In this study, we investigated the effects of Korean red ginseng water extract (KRGE) on hepatic lipid accumulation in HepG2 cells. KRGE decreased hepatic triglyceride and cholesterol levels. Further, KRGE suppressed expression of fatty acid synthase (FAS) and 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase. These results suggest that KRGE may reduce hepatic lipid accumulation by inhibition of FAS and HMG-CoA reductase expression in HepG2 cells.  相似文献   
28.
目的:黄芪是一种传统的提高身体各项机能的中药,本研究旨在探讨黄芪在高原缺氧环境下对运动小鼠疲劳缓解的效果.方法:雄性昆明种小鼠,随机分为对照组和黄芪高、中、低3个剂量组(30.0,3.0,1.0 g/kg),平原对照组在平原环境下饲养,缺氧小鼠在模拟5000m高原环境中饲养,每天灌胃给药,10d后在缺氧环境下进行游泳力竭实验,观察小鼠游泳力竭时间,同时检测血乳酸、血糖、肝糖原以及血清SOD活性和肝脏MDA等指标的变化.结果:与空白对照组比较,黄芪各剂量组可明显提高缺氧小鼠力竭游泳时间(P<0.05),减少血乳酸曲线下面积(P<0.05);黄芪高、中剂量组肝糖原显著增加(P<0.05),力竭游泳后血糖明显升高(P<0.05),SOD活性升高(P<0.05),MDA降低(P<0.05).结论:黄芪可显著缓解高原低氧小鼠的运动疲劳,具有明显的抗高原疲劳效果,具有进一步研究的价值.  相似文献   
29.
目的:探讨凉血活血汤联合阿维A胶囊治疗银屑病的临床疗效及其可能作用机制。方法:选择2012年7月~2015年11月于我院就诊的银屑病患者60例,按照就诊先后顺序分为实验组与对照组,每组各30例,实验组患者使用凉血活血汤联合阿维A胶囊进行治疗,对照组患者仅给予阿维A胶囊进行治疗。比较治疗前后两组患者血清白细胞介素17(IL-17)、白细胞介素22(IL-22)、白细胞介素23(IL-23)及血管内皮因子(VEGF)水平,同时比较两组患者的不良反应发生率及临床总有效率。结果:与治疗前相比,两组患者血清IL-17、IL-22、IL-23及VEGF水平均降低;治疗结束后与对照组相比,实验组患者血清IL-17、IL-22、IL-23及VEGF水平较低(P0.05);且与对照组相比,实验组患者的不良反应发生率较低(P0.05);临床总有效率较高(P0.05)。结论:凉血活血汤联合阿维A胶囊能明显提高银屑病患者的临床疗效,且安全性较高,可能与其降低血清IL-17、IL-22、IL-23及VEGF水平有关。  相似文献   
30.
Six α-monoglucosyl derivatives of ginsenoside Rg1 (G-Rg1) were synthesized by transglycosylation reaction of rice seed α-glucosidase in the reaction mixture containing maltose as a glucosyl donor and G-Rg1 as an acceptor. Their chemical structures were identified by spectroscopic analysis, and the effects of reaction time, pH, and glycosyl donors on transglycosylation reaction were investigated. The results showed that rice seed α-glucosidase transfers α-glucosyl group from maltose to G-Rg1 by forming either α-1,3 (α-nigerosyl)-, α-1,4 (α-maltosyl)-, or α-1,6 (α-isomaltosyl)-glucosidic linkages in β-glucose moieties linked at the C6- and C20-position of protopanaxatriol (PPT)-type aglycone. The optimum pH range for the transglycosylation reaction was between 5.0 and 6.0. Rice seed α-glucosidase acted on maltose, soluble starch, and PNP α-D-glucopyranoside as glycosyl donors, but not on glucose, sucrose, or trehalose. These α-monoglucosyl derivatives of G-Rg1 were easily hydrolyzed to G-Rg1 by rat small intestinal and liver α-glucosidase in vitro.  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