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   28739篇
  免费   2977篇
  国内免费   1489篇
耳鼻咽喉   274篇
儿科学   311篇
妇产科学   499篇
基础医学   5676篇
口腔科学   561篇
临床医学   1464篇
内科学   3471篇
皮肤病学   606篇
神经病学   1292篇
特种医学   469篇
外国民族医学   15篇
外科学   1890篇
综合类   4794篇
现状与发展   6篇
预防医学   791篇
眼科学   259篇
药学   2870篇
  2篇
中国医学   699篇
肿瘤学   7256篇
  2024年   32篇
  2023年   428篇
  2022年   566篇
  2021年   1098篇
  2020年   962篇
  2019年   769篇
  2018年   671篇
  2017年   783篇
  2016年   765篇
  2015年   1081篇
  2014年   1442篇
  2013年   1491篇
  2012年   1382篇
  2011年   1760篇
  2010年   1528篇
  2009年   1614篇
  2008年   1637篇
  2007年   1719篇
  2006年   1564篇
  2005年   1516篇
  2004年   1446篇
  2003年   1381篇
  2002年   1193篇
  2001年   1157篇
  2000年   1025篇
  1999年   799篇
  1998年   637篇
  1997年   538篇
  1996年   430篇
  1995年   394篇
  1994年   246篇
  1993年   189篇
  1992年   111篇
  1991年   93篇
  1990年   53篇
  1989年   55篇
  1988年   64篇
  1987年   44篇
  1986年   49篇
  1985年   58篇
  1984年   60篇
  1983年   33篇
  1982年   49篇
  1981年   46篇
  1980年   45篇
  1979年   32篇
  1978年   34篇
  1977年   36篇
  1976年   23篇
  1973年   15篇
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
991.
目的探究miR-150-5p靶向SIRT1提高肝癌细胞放射敏感性的作用机制。方法用分次放疗放射递增法诱导建立放射抵抗型细胞株(RR-HepG2);RT-qPCR检测HepG2和RR-HepG2在不同放射剂量下miR-150-5p的表达水平;细胞克隆实验检测相同放射剂量下两种细胞的放疗敏感性;流式细胞计量术和Western blot检测过表达miR-150-5p对HepG2凋亡的影响;双荧光素酶报告基因法检测miR-150-5p与SIRT1的关联;细胞克隆实验和Western blot检测过表达SIRT1后,细胞的放疗敏感性和凋亡蛋白的变化。结果与亲代HepG2比较,相同放射剂量下,RRHepG2组miR-150-5p的表达量均显著降低(P<0. 05);放射处理后,与control、agomiR-NC组比较,agomiR-150-5p组的细胞存活分数显著降低,敏感性高(P<0. 05),Bax、caspase-9蛋白表达水平显著升高,Bcl-2蛋白表达水平显著降低,细胞凋亡率显著升高;双荧光素酶报告基因法验证miR-150-5p靶向调控SIRT1。与agomiR-NC组比较,野生型(WT) agomiR-150-5p荧光素酶活性显著降低,SIRT1蛋白水平显著降低(P<0. 05);与anta-agomiR-NC比较,野生型(WT) anta-agomiR-150-5p荧光素酶活性显著升高,SIRT1蛋白水平显著升高(P<0. 05);放射处理后,与agomiR-NC组比较,agomiR-150-5p组的细胞存活分数显著降低,Bax、caspase-9蛋白表达水平显著升高,Bcl-2蛋白表达水平显著降低(P<0. 05);与agomiR-150-5p+vector组比较,agomiR-150-5p+SIRT1组的细胞存活分数显著升高,Bax、caspase-9蛋白表达水平显著降低,Bcl-2蛋白表达水平显著升高(P<0. 05)。结论 miR-150-5p靶向SIRT1,下调其表达,提高肝癌细胞放射敏感性,可为临床肝癌放射治疗增敏提供靶点。  相似文献   
992.
In recent years, a subgroup of B‐cell precursor acute lymphoblastic leukemia (BCP ALL) without an established abnormality (“B‐other”) has been shown to be characterized by rearrangements of ABL1, ABL2, CSF1R, or PDGFRB (a.k.a. ABL‐class genes). Using FISH with probes for these genes, we screened 55 pediatric and 50 adult B‐other cases. Three (6%) of the adult but none of the childhood B‐other cases were positive for ABL‐class aberrations. RT‐PCR and sequencing confirmed a rare SFPQ‐ABL1 fusion in one adult B‐other case with t(1;9)(p34;q34). Only six SFPQABL1‐positive BCP ALLs have been reported, present case included. A review of these shows that all harbored fusions between exon 9 of SFPQ and exon 4 of ABL1, that the fusion is typically found in adolescents/younger adults without hyperleukocytosis, and that IKZF1 deletions are recurrent. The few patients not treated with tyrosine kinase inhibitors (TKIs) and/or allogeneic stem cell transplantation relapsed, strengthening the notion that TKI should be added to the therapy of SFPQABL1‐positive BCP ALL.  相似文献   
993.
994.
The aberrant expression of matrix metalloproteinases (MMPs) is known to contribute to the pathogenesis of airway remodeling and alveolar disruption in chronic obstructive pulmonary disease (COPD). In the discovery stage, 11 COPD from five families were subjected to whole‐genome sequencing, and 21 common polymorphisms in MMPs and TIMPs were identified. These polymorphisms were genotyped in two subsequent verification studies. Of these polymorphisms, c.2392G>A (rs2664370T>C) and c.4158C>A (rs2664369T>G) in MMP16 remained significantly different. Functionally, we found that MMP16 expression was significantly increased in peripheral blood monocytes (PBMCs) from COPD and in cigarette smoke extract‐treated 16HBE cells compared with controls. This was also shown by bioinformatics analysis. COPD carrying rs2664370CC showed decreased levels of MMP16 in the plasma and in PBMCs compared with those carrying CT and TT. Treatment with hsa‐miR‐576‐5p mimics led to a greater reduction in luciferase reporter activity in cells transfected with rs2664370CC. Moreover, blood levels of base excess, PCO2, and PO2 in COPD with rs2664370CC were significantly lower than those with rs2664370CT+TT. Taken together, these results demonstrate that the rs2664370T>C polymorphism in MMP16 protects against the risk of COPD, likely by favoring interaction with hsa‐miR‐576‐5p, leading to reduced MMP16 expression and improved blood gas levels.  相似文献   
995.
996.
Immunohistochemically p16 (CDKN2A)‐negative uterine cervical squamous cell carcinoma (SCC) is uncommon, and there are few reports about its pathological features. This study explored the causes of p16 negativity in such cases. We analyzed diagnostic tissue samples of five cases of p16‐negative cervical SCC among 107 patients who underwent hysterectomy at Kyoto University Hospital between January 2010 and December 2015. The samples were subjected to immunohistochemical staining, in situ hybridization and a genetic analysis. Two of five cases were positive for human papilloma virus (HPV) by genotyping. One was positive for HPV56 with promoter hypermethylation of CDKN2A and co‐existing Epstein–Barr virus infection. Another was positive for HPV6 categorized as low‐risk HPV with condylomatous morphology. Among the remaining three cases, one had amplification of the L1 gene of HPV with promoter hypermethylation of CDKN2A and TP53 mutation, and one of the other two HPV‐negative cases had a homozygous CDKN2A deletion, while the other was positive for p53 and CK7. p16‐negativity of cervical SCC is often associated with an unusual virus infection status and CDKN2A gene abnormality.  相似文献   
997.
Microglial inflammation is identified as a key process associated with Parkinson's disease (PD) pathogenesis. Our previous study showed that miR‐29c‐3p (miR‐29c) exhibited anti‐inflammatory properties in PD animal and neuronal models. However, the specific role and regulatory mechanism of miR‐29c played in microglia are still unclear. In this study, lipopolysaccharide (LPS)‐stimulated BV‐2 cells were used to establish a cellular model of microglial activation for investigating PD. The results showed a decreased expression of miR‐29c in LPS‐induced BV‐2 cells. Over‐expression of miR‐29c suppressed LPS‐triggered Iba‐1 increment, pro‐inflammatory cytokine release, and NF‐кB and TXNIP/NLRP3 inflammasome activation. Silence of miR‐29c induced similar effects with LPS on microglial inflammation. In addition, we found that NFAT5 was negatively correlated with miR‐29c. Knockdown of NFAT5 blocked the aggravated inflammation in microglia treated by miR‐29c inhibitor. Thus, these findings suggest that miR‐29c modulates NLRP3 inflammasome to impair microglial inflammatory responses by targeting NFAT5, which represents a promising therapeutic target for PD.  相似文献   
998.
We identified a de novo 44.7 Kb interstitial 12p13.33 micro-deletion that involves solely the first exon of the CACNA1C (MIM 114205), using microarray-based comparative genomic hybridization (aCGH). The associated main phenotype is characterized by expressive language impairment, tremors, fine motor-skills delay, muscular hypotonia, and joint laxity. A careful comparison between the clinical and genomic characteristics between our proband and 20 previously reported patients, led us to propose CACNA1C haploinsufficiency as the main cause of both expressive language delay and motor-skills impairment. Pathogenic variants of CACNA1C have been associated to a plethora of clinical phenotypes, such as Timothy syndrome (TS, OMIM 601005), Brugada syndrome (BRGDA3, OMIM 611875) and a variety of neuropsychiatric disorders (bipolar disorder, major depression, schizophrenia, autism spectrum disorder, psychotic manifestations). In this report we describe a 12p13.33 micro-deletion involving one coding gene only, in contrast with previous studies that mostly concluded that a multi-genes deletion in the 12p13.33 sub-telomeric region is responsible of the minimum clinical phenotype of patients with 12p13.33 monosomy. Certainly, larger deletions spanning multiple Mb in 12p13.33 are responsible for more severe phenotypes, associated to a variable degree of dysmorphic features.  相似文献   
999.
1000.
Alpinumisoflavone (AIF) as a principal active ingredient of traditional Chinese herb Derris eriocarpa exerts a broad spectrum of anticancer activities against solid tumors. However, little is known about the effect of AIF on papillary thyroid cancer (PTC). Objectives of this study are to investigate the effect of AIF on cell growth, apoptosis, and metastasis of PTC cells and uncover its underlying mechanisms. Results showed that AIF treatment notably suppressed cell viability, migration, invasion, and epithelial–mesenchymal transition (EMT) process, as well as induced apoptotic cell death. In addition, microarray analysis results revealed that miR-141-3p level was dramatically elevated upon AIF insulation, suggesting that miR-141-3p may mediate the suppressive role of AIF against PTC. Moreover, miR-141-3p knockdown effectively reversed the effects of AIF on cell growth, migration, invasion, and EMT, while promoted PTC cell apoptosis escape. Furthermore, in vivo findings also confirmed that the antigrowth and antimetastasis activities of AIF were, at least partly, mediated by upregulation of miR-141-3p. Overall, AIF could serve as a potential anticancer compound for PTC treatment. Anat Rec, 2019. © 2019 American Association for Anatomy Anat Rec, 303:1842–1850, 2020. © 2019 American Association for Anatomy  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