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   549篇
  免费   43篇
  国内免费   78篇
  2024年   1篇
  2023年   6篇
  2022年   15篇
  2021年   21篇
  2020年   24篇
  2019年   31篇
  2018年   35篇
  2017年   20篇
  2016年   33篇
  2015年   41篇
  2014年   50篇
  2013年   53篇
  2012年   47篇
  2011年   46篇
  2010年   22篇
  2009年   14篇
  2008年   21篇
  2007年   35篇
  2006年   31篇
  2005年   16篇
  2004年   30篇
  2003年   16篇
  2002年   13篇
  2001年   4篇
  2000年   10篇
  1999年   5篇
  1998年   6篇
  1997年   6篇
  1996年   5篇
  1995年   1篇
  1994年   4篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1990年   1篇
  1984年   1篇
  1983年   2篇
排序方式: 共有670条查询结果,搜索用时 15 毫秒
661.
Niu  Lu  He  Hongli  Zhang  Yuanyu  Yang  Jing  Zhao  Qianqian  Xing  Guojie  Zhong  Xiaofang  Yang  Xiangdong 《Transgenic research》2021,30(1):1-9
Transgenic Research - Genomic insertions and flanking regions of transgenes in host genomes constitute a critical component of precise molecular characterization and event-specific detection, which...  相似文献   
662.
663.
[背景] 由于抗生素的滥用,导致“超级细菌”出现,寻找新的抗菌药物将有效地应对细菌耐药问题,因为大多数抗菌药物都是从微生物中发现的,所以药用植物内生真菌的研究拓宽了药用资源,并且具有巨大的应用价值。[目的] 对采自江西九江庐山植物园的决明草进行内生真菌分离,筛选出拮抗菌株,并对拮抗菌株的次级代谢产物进行分离,分析其抗菌物质理化性质,为新型抗菌物质的研究提供基础数据。[方法] 用管碟法筛选拮抗菌株,并根据形态学特征和分子生物学的方法鉴定菌株,采用硅胶柱层析、葡聚糖凝胶LH-20柱层析和RP-C18柱层析对其次级代谢产物进行分离,并用液质联用(高分辨飞行时间质谱)和能谱仪分析所得抗菌物质的分子量和分子式。[结果] 筛选到一株广谱拮抗活性菌株桔青霉ZH-11,通过管碟法显示其对大肠杆菌、金黄色葡萄球菌、苏云金芽孢杆菌、水稻黄单胞菌、枯草芽孢杆菌、地衣芽孢杆菌、白色念珠菌、蜡样芽孢杆菌这8株指示菌均有较好的抑菌效果。从桔青霉ZH-11次级代谢产物中分离得到纯化合物Y3,其分子量为410.169 1,分子式为C24H26O6。当Y3浓度为10 μg/mL时,其对大肠杆菌和苏云金芽胞杆菌的抑菌圈直径分别为16.23 mm和17.27 mm。[结论] 菌株桔青霉ZH-11的活性物质与已知的来源于桔青霉类的抗菌活性物质不同,该研究结果为进一步挖掘桔青霉属的活性产物奠定基础,同时丰富了人们对决明草内生真菌的认识。  相似文献   
664.
665.
As a traditional Chinese medicine, Rhododendron molle G. Don has a long history of treating rheumatoid arthritis. In this study, RAW 264.7 cells induced by lipopolysaccharide (LPS) were established as cell inflammatory model to evaluate the anti-inflammatory activity of chloroform extract from R. molle leaves (CERL), ethyl acetate extract from R. molle leaves (EERL) and butanol extract from R. molle leaves (BERL) and analyze the potential anti-inflammatory components of R. molle. Potential anti-inflammatory components analysis of CERL were performed by HPLC and UHPLC-Q-TOF-MS. Prediction of potential anti-inflammatory components by molecular docking experiments. Compared with negative control group, 25 μg/mL CERL could reduce the release level of NO by 62 %, and the mRNA expression levels of COX-2, IL-6, IL-1β and TNF-α were reduced by 69.74 %, 86.25 %, 77.94 % and 56.80 %, respectively. Western-Blot showed similar results. CERL, EERL and BERL exerted their inhibitory activity in dose-dependent manner. All results showed that the higher the concentration, the better the anti-inflammatory activity. CERL showed the best inhibitory activity, the second was EERL, and then was BERL. 21 terpenoids and 4 flavonoids were identified in CERL by UHPLC-Q-TOF-MS. Molecular docking results showed that triterpenoids in CERL had better interaction with target proteins (TNF-α, IL-1β). It indicated that triterpenoids may be potential anti-inflammatory components of R. molle leaves. This study explored the anti-inflammatory activities of CERL, EERL, BERL, which laid a foundation for further promoting the clinical application of R. molle.  相似文献   
666.
667.

Heparosan, the capsular polysaccharide discovered in many pathogenic bacteria, is a promising material for heparin preparation. In this study, the Pasteurella multocida heparosan synthase 1 (PmHS1) module was used to synthesize heparosan with controlled molecular weight, while tuaD/gtaB module or gcaD module was responsible for UDP-precursors production in Bacillus subtilis 168. After metabolic pathway optimization, the yield of heparosan was as high as 237.6 mg/L in strain containing PmHS1 module and tuaD/gtaB module, which indicated that these two modules were key factors in heparosan production. The molecular weight of heparosan varied from 39 to 53 kDa, which indicated that heparosan molecular weight could be adjusted by the amount of PmHS1 and the ratio of two UDP precursors. The results showed that it would be possible to produce safe heparosan with appropriate molecular weight which is useful in heparin production.

  相似文献   
668.
669.
670.
Gastric cancer has the fifth highest incidence of disease and is the third leading cause of cancer-associated mortality in the world. The etiology of gastric cancer is complex and needs to be fully elucidated. Thus, it is necessary to explore potential pathogenic genes and pathways that contribute to gastric cancer. Gene expression profiles of the GSE33335 and GSE54129 datasets were downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) were compared and identified using R software. The DEGs were then subjected to gene set enrichment analysis and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses. Survival analyses based on The Cancer Genome Atlas database were used to further screen the essential DEGs. A knockdown assay was performed to determine the function of the candidate gene in gastric cancer. Finally, the association between the candidate gene and immune-related genes was investigated. We found that GPNMB serves as an essential gene, with a high expression level, and predicts a worse outcome of gastric cancer. Knockdown of GPNMB inhibited gastric cancer cell proliferation and migration. In addition, GPNMB may augment the immunosuppressive ability of gastric cancer by recruiting immunosuppressive cells and promoting immune cell exhaustion through PI3K/AKT/CCL4 signaling axis. Collectively, these data suggest that GPNMB acts as an important positive mediator of tumor progression in gastric cancer, and GPNMB could exert multimodality modulation of gastric cancer-mediated immune suppression.  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