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   106381篇
  免费   8929篇
  国内免费   8719篇
  2023年   1269篇
  2022年   1615篇
  2021年   5024篇
  2020年   3799篇
  2019年   4726篇
  2018年   4468篇
  2017年   3272篇
  2016年   4633篇
  2015年   6741篇
  2014年   7918篇
  2013年   8399篇
  2012年   10076篇
  2011年   9080篇
  2010年   5590篇
  2009年   5034篇
  2008年   5762篇
  2007年   5191篇
  2006年   4522篇
  2005年   3540篇
  2004年   3004篇
  2003年   2749篇
  2002年   2298篇
  2001年   1881篇
  2000年   1707篇
  1999年   1680篇
  1998年   1022篇
  1997年   982篇
  1996年   923篇
  1995年   833篇
  1994年   799篇
  1993年   624篇
  1992年   825篇
  1991年   618篇
  1990年   470篇
  1989年   446篇
  1988年   354篇
  1987年   345篇
  1986年   266篇
  1985年   286篇
  1984年   156篇
  1983年   161篇
  1982年   99篇
  1981年   86篇
  1980年   60篇
  1979年   77篇
  1977年   59篇
  1975年   56篇
  1974年   52篇
  1973年   56篇
  1972年   49篇
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
101.
102.
103.
  相似文献   
104.
105.
106.
  相似文献   
107.
An integrated multi-trophic aquaculture (IMTA) system, with one fish cage model surrounded by an island and shellfish rafts, was used in the current study. Planktonic and sediment bacterial communities in the IMTA system were monitored over four seasons in 2019. In both plankton and sediment samples, the most dominant phyla were Proteobacteria and Bacteroidota. Sediment bacterial samples were more similar and had higher levels of biodiversity than planktonic bacterial samples. Obvious seasonal variations were found in plankton samples, but not in sediment samples. No obvious inter-site variations in planktonic and sediment bacteria (fish cages, shellfish rafts and control sites) were found and the results suggested that no obvious impact of feeding operations in fish culture cage model on bacterial communities in the IMTA system was observed in this study. Based on the sequence data, some faecal indicator bacteria and potentially pathogenic bacterial species were detected. According to the results, the bacterial water quality in the IMTA system was acceptable. PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) analysis revealed that the primary difference in potential functional roles of planktonic and sediment bacteria was amino acid transport and metabolism, which was active in different seasons.  相似文献   
108.
This study aims to explore the potential mechanisms of Xinnaokang in atherosclerosis treatment. Firstly, the active components of Xinnaokang were analysed by HPLC, which contains ginsenoside Rg1, puerarin, tanshinone, notoginsenoside R1, ammonium glycyrrhizate and glycyrrhizin. Network pharmacology analysis showed there were 145 common targets of Xinnaokang, including the chemical stress, lipid metabolite, lipopolysaccharide, molecules of bacterial origin, nuclear receptor and fluid shear stress pathways. Then, the animal experiment showed that Xinnaokang reduced the body weight and blood lipid levels of atherosclerotic mice. Vascular plaque formation was increased in atherosclerotic mice, which was markedly reversed by Xinnaokang. In addition, Xinnaokang reduced CAV-1 expression and increased ABCA1, SREBP-1 and LXR expressions in the vasculature. Xinnaokang promoted SREBP-2 and LDLR expressions in the liver but decreased IDOL and PCSK9 expressions, indicating that Xinnaokang regulated lipid transport-related protein expression. Cecal microbiota diversity was reduced in atherosclerotic mice but increased after Xinnaokang treatment. Xinnaokang treatment also improved gut microbiota communities by enriching Actinobacteria, Bifidobacteriales and Bifidobacteriaceae abundances. Metabolic profile showed that Xinnaokang significantly reduced homogentisate, phenylacetylglycine, alanine and methionine expressions in the liver of atherosclerotic mice. Xinnaokang effectively alleviated atherosclerosis, and this effect might be linked with the altered features of the liver metabolite profiles and cecal microbiota.  相似文献   
109.
Wang  Meng  Feng  Zhigang  Li  Xiaoxi  Sun  Shulan  Lu  Li 《Molecular and cellular biochemistry》2021,476(6):2561-2571
Molecular and Cellular Biochemistry - LncRNAs have been proposed to be associated with the tumorigenesis and progression of oral squamous cell carcinoma (OSCC). LncRNA HLA complex group 22 (HCG22)...  相似文献   
110.
Plant Cell, Tissue and Organ Culture (PCTOC) - For the first time, the effect of mechanocomposite (MC) based on biogenic silica and green-tea catechins on axillary shoot formation, physiological...  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