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   7535篇
  免费   663篇
  国内免费   972篇
  2024年   19篇
  2023年   99篇
  2022年   285篇
  2021年   423篇
  2020年   318篇
  2019年   389篇
  2018年   361篇
  2017年   280篇
  2016年   328篇
  2015年   454篇
  2014年   574篇
  2013年   640篇
  2012年   725篇
  2011年   627篇
  2010年   416篇
  2009年   378篇
  2008年   412篇
  2007年   365篇
  2006年   325篇
  2005年   280篇
  2004年   260篇
  2003年   254篇
  2002年   192篇
  2001年   160篇
  2000年   108篇
  1999年   99篇
  1998年   73篇
  1997年   47篇
  1996年   54篇
  1995年   42篇
  1994年   39篇
  1993年   30篇
  1992年   22篇
  1991年   23篇
  1990年   13篇
  1989年   13篇
  1988年   9篇
  1987年   13篇
  1986年   4篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1982年   4篇
  1981年   2篇
  1950年   1篇
排序方式: 共有9170条查询结果,搜索用时 93 毫秒
61.
Numerous studies have demonstrated that thioredoxin-interacting protein (TXNIP) expression of peripheral blood leucocytes is increased in coronary artery disease (CAD). However, the molecular mechanism of this phenomenon remained unclear. DNA methylation plays important roles in the regulation of gene expression. Therefore, we speculated there might be a close association between the expression of TXNIP and methylation. In this study, we found that compared with controls, DNA methylation at cg19693031 was decreased in CAD, while mRNA expressions of TXNIP and inflammatory factors, NLRP3, IL-1β, IL-18, were increased. Methylation at cg19693031 was negatively associated with TXNIP expression in the cohort, THP-1 and macrophages/foam cells. Furthermore, Transwell assay and co-cultured adhesion assay were performed to investigate functions of TXNIP on the migration of THP-1 or the adhesion of THP-1 on the surface of endothelial cells, respectively. Notably, overexpressed TXNIP promoted the migration and adhesion of THP-1 cells and expressions of NLRP3, IL-18 and IL-1β. Oppositely, knock-down TXNIP inhibited the migration and adhesion of THP-1 and expressions of NLRP3, IL-18. In conclusion, increased TXNIP expression, related to cg19693031 demethylation orientates monocytes towards an inflammatory status through the NLRP3 inflammasome pathway involved in the development of CAD.  相似文献   
62.
A growing number of studies recognize that long non‐coding RNAs (lncRNAs) are essential to mediate multiple tumorigenic processes, including hepatic tumorigenesis. However, the pathological mechanism of lncRNA‐regulated liver cancer cell growth remains poorly understood. In this study, we identified a novel function lncRNA, named polo‐like kinase 4 associated lncRNA (lncRNA PLK4, GenBank Accession No. RP11‐50D9.3), whose expression was dramatically down‐regulated in hepatocellular carcinoma (HCC) tissues and cells. Interestingly, talazoparib, a novel and highly potent poly‐ADP‐ribose polymerase 1/2 (PARP1/2) inhibitor, could increase lncRNA PLK4 expression in HepG2 cells. Importantly, we showed that talazoparib‐induced lncRNA PLK4 could function as a tumour suppressor gene by Yes‐associated protein (YAP) inactivation and induction of cellular senescence to inhibit liver cancer cell viability and growth. In summary, our findings reveal the molecular mechanism of talazoparib‐induced anti‐tumor effect, and suggest a potential clinical use of talazoparib‐targeted lncRNA PLK4/YAP‐dependent cellular senescence for the treatment of HCC.  相似文献   
63.
There are many different types of cardiovascular diseases, which impose a huge economic burden due to their extremely high mortality rates, so it is necessary to explore the underlying mechanisms to achieve better supportive and curative care outcomes. Sphingosine 1‐phosphate (S1P) is a bioactive lipid mediator with paracrine and autocrine activities that acts through its cell surface S1P receptors (S1PRs) and intracellular signals. In the circulatory system, S1P is indispensable for both normal and disease conditions; however, there are very different views on its diverse roles, and its specific relevance to cardiovascular pathogenesis remains elusive. Here, we review the synthesis, release and functions of S1P, specifically detail the roles of S1P and S1PRs in some common cardiovascular diseases, and then address several controversial points, finally, we focus on the development of S1P‐based therapeutic approaches in cardiovascular diseases, such as the selective S1PR1 modulator amiselimod (MT‐1303) and the non‐selective S1PR1 and S1PR3 agonist fingolimod, which may provide valuable insights into potential therapeutic strategies for cardiovascular diseases.  相似文献   
64.
Alloy materials such as Si and Ge are attractive as high‐capacity anodes for rechargeable batteries, but such anodes undergo severe capacity degradation during discharge–charge processes. Compared to the over‐emphasized efforts on the electrode structure design to mitigate the volume changes, understanding and engineering of the solid‐electrolyte interphase (SEI) are significantly lacking. This work demonstrates that modifying the surface of alloy‐based anode materials by building an ultraconformal layer of Sb can significantly enhance their structural and interfacial stability during cycling. Combined experimental and theoretical studies consistently reveal that the ultraconformal Sb layer is dynamically converted to Li3Sb during cycling, which can selectively adsorb and catalytically decompose electrolyte additives to form a robust, thin, and dense LiF‐dominated SEI, and simultaneously restrain the decomposition of electrolyte solvents. Hence, the Sb‐coated porous Ge electrode delivers much higher initial Coulombic efficiency of 85% and higher reversible capacity of 1046 mAh g?1 after 200 cycles at 500 mA g?1, compared to only 72% and 170 mAh g?1 for bare porous Ge. The present finding has indicated that tailoring surface structures of electrode materials is an appealing approach to construct a robust SEI and achieve long‐term cycling stability for alloy‐based anode materials.  相似文献   
65.
66.
为探究PPARγ与c/EBPα基因在苏太猪不同组织中的表达与脂肪沉积的关系,本实验以10月龄苏太猪为研究对象,运用实时荧光定量PCR (q RT-PCR)技术检测PPARγ与c/EBPα基因mRNA在苏太猪心、肝、脾、肺、肾、胃、背最长肌和皮下脂肪8个组织中的表达水平。结果表明,PPARγ与c/EBPα基因在苏太猪的8个组织中均有不同程度的表达,其中,PPARγ基因在苏太猪脾脏组织中的表达量最高,皮下脂肪中的表达水平仅次于脾;以背最长肌中PPARγ基因的相对表达量作对比,背最长肌与脾、肺和皮下脂肪的相对表达差异极显著(p<0.01),其余为差异不显著(p>0.05),表达量高低顺序为脾>皮下脂肪>肺>心>胃>肾>肝>背最长肌;c/EBPα基因在苏太猪的皮下脂肪的表达量最高,以背最长肌中c/EBPα基因的相对表达量作对比,在肝、脾、皮下脂肪组织中表达差异极显著(p<0.01),肺的相对表达差异显著(p<0.05),其余组织中差异不显著(p>0.05),表达量的高低顺序为皮下脂肪>肝>脾>肺>肾>心>胃>背最长肌。两基因在各组织中表达趋势趋于一致。试验结果表明PPARγ和c/EBPα基因可能对猪脂肪沉积有重要影响。  相似文献   
67.
In China, three institutes for botanical research were established in the 1920s. They were the Department of Botany, Biological Laboratory of the Science Society of China (1922, Nanjing), the Fan Memorial Institute of Biology (1928, Beiping), and the Institute of Botany, Beiping Academy of Sciences (1929, Beiping).  相似文献   
68.
Ba  Limin  Wang  Zhenbao  Liu  William J  Wu  Dongxun  Xiang  Wangzhen  Qi  Peng  Dong  Chunna  Hu  Yanxin  Lu  Ping  Xiao  Jin  Yu  Changyuan 《中国科学:生命科学英文版》2020,63(10):1604-1607
正Dear Editor,Swine major histocompatibility complex (MHC) is a highly polymorphic gene in pigs and is also called swine leukocyte antigen (SLA)(Fan et al., 2018). SLA is divided into three major categories, SLA Ⅰ (SLA-1,-2,-3), SLA Ⅱ, and SLA Ⅲ(Smith et al., 2005). SLA Ⅰ plays an important role in cellular immunity which can eliminate viruses and other foreign  相似文献   
69.
Idiopathic pulmonary fibrosis (IPF) is a progressive disease characterized by excessive deposition of extracellular matrix (ECM) and chronic inflammation with limited therapeutic options. Psoralen, a major active component extracted from Psoralea corylifolia L. seed, has several biological effects. However, the role of psoralen in IPF is still unclear. Here, we hypothesized that psoralen played an essential role in IPF in the inhibition of fibroblast proliferation and inflammatory response. A murine model of IPF was established by injecting bleomycin (BLM) intratracheally, and psoralen was administered for 14 days from the 7th to 21st day after BLM injection. Our results demonstrated that psoralen treatment reduced body weight loss and improved the survival rate of mice with IPF. Histological and immunofluorescent examination showed that psoralen alleviated BLM‐induced lung parenchymal inflammatory and fibrotic alteration. Furthermore, psoralen inhibited proliferation and collagen synthesis of mouse fibroblasts and partially reversed BLM‐induced expression of α‐smooth muscle actin at both the tissue and cell level. Moreover, psoralen decreased the expression of transforming growth factor‐β1, interleukin‐1β, and tumor necrosis factor‐α in the lungs of BLM‐stimulated mice. Our results reveale for the first time that psoralen exerts therapeutic effects against IPF in a BLM‐induced murine model.  相似文献   
70.
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