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   7598篇
  免费   667篇
  国内免费   960篇
  2024年   12篇
  2023年   99篇
  2022年   177篇
  2021年   431篇
  2020年   331篇
  2019年   403篇
  2018年   378篇
  2017年   286篇
  2016年   338篇
  2015年   461篇
  2014年   591篇
  2013年   663篇
  2012年   739篇
  2011年   620篇
  2010年   414篇
  2009年   379篇
  2008年   398篇
  2007年   373篇
  2006年   335篇
  2005年   290篇
  2004年   267篇
  2003年   259篇
  2002年   203篇
  2001年   156篇
  2000年   104篇
  1999年   98篇
  1998年   77篇
  1997年   60篇
  1996年   55篇
  1995年   44篇
  1994年   43篇
  1993年   29篇
  1992年   21篇
  1991年   23篇
  1990年   12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9225条查询结果,搜索用时 34 毫秒
71.
Recent studies have shown that tumour necrosis factor‐α–induced protein 8 like‐1(TIPE1) plays distinct roles in different cancers. TIPE1 inhibits tumour proliferation and metastasis in a variety of tumours but acts as an oncogene in cervical cancer. The role of TIPE1 in nasopharyngeal carcinoma (NPC) remains unknown. Interestingly, TIPE1 expression was remarkably increased in NPC tissue samples compared to adjacent normal nasopharyngeal epithelial tissue samples in our study. TIPE1 expression was positively correlated with that of the proliferation marker Ki67 and negatively correlated with patient lifespan. In vitro, TIPE1 inhibited autophagy and induced cell proliferation in TIPE1‐overexpressing CNE‐1 and CNE‐2Z cells. In addition, knocking down TIPE1 expression promoted autophagy and decreased proliferation, whereas overexpressing TIPE1 increased the levels of pmTOR, pS6 and P62 and decreased the level of pAMPK and the LC3B. Furthermore, the decrease in autophagy was remarkably rescued in TIPE1‐overexpressing CNE‐1 and CNE‐2Z cells treated with the AMPK activator AICAR. In addition, TIPE1 promoted tumour growth in BALB/c nude mice. Taken together, results indicate that TIPE1 promotes NPC progression by inhibiting autophagy and inducing cell proliferation via the AMPK/mTOR signalling pathway. Thus, TIPE1 could potentially be used as a valuable diagnostic and prognostic biomarker for NPC.  相似文献   
72.
Osteoarthritis (OA) is a common joint disease in the middle and old age group with obvious cartilage damage, and the regeneration of cartilage is the key to alleviating or treating OA. In stem cell therapy, bone marrow stem cell (BMSC) has been confirmed to have cartilage regeneration ability. However, the role of stem cells in promoting articular cartilage regeneration is severely limited by their low homing rate. Stromal cell‐derived factor‐1α (SDF‐1α) plays a vital role in MSC migration and involves activation, mobilization, homing and retention. So, we aim to develop SDF‐1α‐loaded microbubbles MB(SDF‐1α), and to verify the migration of BMSCs with the effect of ultrasound combined with MB(SDF‐1α) in vitro and in vivo. The characteristics of microbubbles and the content of SDF‐1α were examined in vitro. To evaluate the effect of ultrasound combined with chemotactic microbubbles on stem cell migration, BMSCs were injected locally and intravenously into the knee joint of the OA model, and the markers of BMSCs in the cartilage were detected. We successfully prepared MB(SDF‐1α) through covalent bonding with impressive SDF‐1α loading efficacy loading content. In vitro study, ultrasound combined with MB(SDF‐1α) group can promote more stem cell migration with highest migrating cell counts, good cell viability and highest CXCR4 expression. In vivo experiment, more BMSCs surface markers presented in the ultrasound combined with MB(SDF‐1α) group with or without exogenous BMSCs administration. Hence, ultrasound combined with MB(SDF‐1α) could promote the homing of BMSCs to cartilage and provide a novel promising therapeutic approach for OA.  相似文献   
73.
Chronic pancreatitis (CP) is characterized by persistent inflammation of the pancreas that results in progressive loss of the endocrine and exocrine compartment owing to atrophy and/or replacement with fibrotic tissue. Currently, the clinical therapeutic scheme of CP is mainly symptomatic treatment including pancreatic enzyme replacement, glycaemic control and nutritional support therapy, lacking of specific therapeutic drugs for prevention and suppression of inflammation and fibrosis aggravating in CP. Here, we investigated the effect of isoliquiritigenin (ILG), a chalcone‐type dietary compound derived from licorice, on pancreatic fibrosis and inflammation in a model of caerulein‐induced murine CP, and the results indicated that ILG notably alleviated pancreatic fibrosis and infiltration of macrophages. Further in vitro studies in human pancreatic stellate cells (hPSCs) showed that ILG exerted significant inhibition on the proliferation and activation of hPSCs, which may be due to negative regulation of the ERK1/2 and JNK1/2 activities. Moreover, ILG significantly restrained the M1 polarization of macrophages (RAW 264.7) via attenuation of the NF‐κB signalling pathway, whereas the M2 polarization was hardly affected. These findings indicated that ILG might be a potential anti‐inflammatory and anti‐fibrotic therapeutic agent for CP.  相似文献   
74.
CircPRTM5 is associated with cell proliferation and migration in many kinds of malignancies. However, the functions and mechanisms of CircPRTM5 in CRC progression remain unclear. We explored the role and the mechanisms of CircPRTM5 in the development of CRC. Tissues of CRC patients and matched adjacent non-tumour tissues were collected to evaluate the expression of CircPRTM5. The expression of CircPRTM5 in CRC tissues was significantly higher than that in adjacent tissues. The biological functions of CircPRTM5 in CRC were determined by overexpression and down-regulation of CircPRTM5 in CRC cells in vitro and in vivo. The results indicate that knockdown of CircPRTM5 can significantly inhibit the proliferation of CRC cells. The potential mechanisms of CircPRTM5 in CRC development were identified by RT-qPCR, Western blotting analysis and luciferase reporter assay. CircPRTM5 competitively regulates the expression of E2F3 by capillary adsorption of miR-377. CircPRMT5 regulates CRC proliferation by regulating the expression of E2F3, which affects the expression of the cell cycle-associated proteins cyclinD1 and CDK2. CircPRTM5 exerts critical regulatory role in CRC progression by sponging miR-377 to induce E2F3 expression.  相似文献   
75.
76.
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   
77.
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   
78.
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   
79.
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   
80.
目的:分析腰大池引流联合法舒地尔治疗动脉瘤性蛛网膜下腔出血的疗效及对血清可溶性细胞间黏附分子-1(sICAM-1)、脂肪酸结合蛋白质(FABP)、核细胞趋化蛋白(MCP-1)水平和脑积水形成的影响。方法:选择我院2016年3月~2018年3月收治的112例动脉瘤性蛛网膜下腔出血患者,按随机数字表法分为对照组(n=48)和研究组(n=64)。对照组采用腰大池引流治疗,研究组基于对照组联合法舒地尔治疗。比较两组临床疗效,治疗前后血清sICAM-1、FABP、MCP-1水平、血压、大脑中动脉血流参数水平和神经功能的变化,脑积水发生率及不良反应发生情况。结果:治疗后,研究组总有效率显著高于对照组(89.02%vs.72.91%,P<0.05)。两组治疗后血清sICAM-1、FABP、MCP-1、血压、大脑中动脉血流参数水平和神经功能缺损评分量表(NIHSS)均较治疗前下降,格拉斯哥昏迷评分(GCS)均较治疗前上升,研究组以上指标较对照组改变更明显(均P<0.05)。两组不良反应发生情况比较差异无统计学意义(P>0.05)。结论:腰大池引流联合法舒地尔治疗动脉瘤性蛛网膜下腔出血的疗效明显优于单用腰大池引流治疗,其可显著降低血清sICAM-1、FABP、MCP-1水平,降低脑积水发生率,改善患者预后。  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