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   5697篇
  免费   691篇
  国内免费   332篇
  6720篇
  2024年   46篇
  2023年   167篇
  2022年   228篇
  2021年   392篇
  2020年   381篇
  2019年   601篇
  2018年   339篇
  2017年   184篇
  2016年   180篇
  2015年   208篇
  2014年   402篇
  2013年   433篇
  2012年   284篇
  2011年   301篇
  2010年   202篇
  2009年   231篇
  2008年   210篇
  2007年   221篇
  2006年   199篇
  2005年   151篇
  2004年   147篇
  2003年   122篇
  2002年   120篇
  2001年   99篇
  2000年   86篇
  1999年   71篇
  1998年   64篇
  1997年   66篇
  1996年   59篇
  1995年   72篇
  1994年   66篇
  1993年   50篇
  1992年   54篇
  1991年   36篇
  1990年   48篇
  1989年   18篇
  1988年   28篇
  1987年   19篇
  1986年   14篇
  1985年   28篇
  1984年   28篇
  1983年   13篇
  1982年   12篇
  1981年   9篇
  1980年   11篇
  1979年   10篇
  1978年   4篇
  1976年   1篇
  1975年   2篇
  1974年   2篇
排序方式: 共有6720条查询结果,搜索用时 18 毫秒
101.
Renal cell carcinoma (RCC) is associated with a high frequency of metastasis and only few therapies substantially prolong survival. Honokiol, isolated from Magnolia spp. bark, has been shown to exhibit pleiotropic anticancer effects in many cancer types. However, whether honokiol could suppress RCC metastasis has not been fully elucidated. In the present study, we found that honokiol suppressed renal cancer cells’ metastasis via dual-blocking epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC) properties. In addition, honokiol inhibited tumor growth in vivo. It was found that honokiol could up-regulate miR-141, which targeted ZEB2 and modulated ZEB2 expression. Honokiol reversed EMT and suppressed CSC properties partly through the miR-141/ZEB2 axis. Our study suggested that honokiol may be a suitable therapeutic strategy for RCC treatment.  相似文献   
102.
Small cell lung carcinoma (SCLC) is a highly aggressive cancer with low survival rate. Although initial response to chemotherapy in SCLC patients is well-rated, the treatments applied after the disease relapses are not successful. Drug resistance is accepted to be one of the main reasons for this failure. Therefore, there is an urgent need for new treatment strategies for SCLC. Meclofenamic acid, a nonsteroidal anti-inflammatory drug, has been shown to have anticancer effects on various types of cancers via different mechanisms. The aim of this study was to investigate the alterations that meclofenamic acid caused on a SCLC cell line, DMS114 using the tools of proteomics namely two-dimensional gel electrophoresis coupled to MALDI-TOF/TOF and nHPLC coupled to LC-MS/MS. Among the proteins identified by both methods, those showing significantly altered expression levels were evaluated using bioinformatics databases, PANTHER and STRING. The key altered metabolism upon meclofenamic acid treatment appeared to the cellular energy metabolism. Glycolysis was suppressed, whereas mitochondrial activity and oxidative phosphorylation were boosted. The cells underwent metabolic reprogramming to adapt into their new environment for survival. Metabolic reprogramming is known to cause drug resistance in several cancer types including SCLC. The identified differentially regulated proteins in here associated with energy metabolism hold value as the potential targets to overcome drug resistance in SCLC treatment.  相似文献   
103.
Oral Squamous Cell Carcinoma (OSCC) is a serious and one of the most common and highly aggressive malignancies. Epigenetic factors such as DNA methylation have been known to be implicated in a number of cancer etiologies. The main objective of this study was to investigate physiognomies of Promoter DNA methylation patterns associated with oral cancer epigenome with special reference to the ethnic population of Meghalaya, North East India. The present study identifies 27,205 CpG sites and 3811 regions that are differentially methylated in oral cancer when compared to matched normal. 45 genes were found to be differentially methylated within the promoter region, of which 38 were hypermethylated and 7 hypomethylated. 14 of the hypermethylated genes were found to be similar to that of the TCGA-HNSCC study some of which are TSGs and few novel genes which may serve as candidate methylation biomarkers for OSCC in this poorly characterized ethnic group.  相似文献   
104.
Ovarian cancer (OC) is ranked the first among the cancers threatening women's health. It attracts tremendous attention of cancer researchers because of its extremely high mortality rate. Recent studies have indicated that traditional herbal medicines (THMs) can play a pivotal role in cancer prevention and treatment. THMs are gaining popularity as a source of anti‐cancer agents. The plant of Balanophora polyandra, which has been used as a traditional herbal medicine, has been known for exhibiting potential haemostatic, analgesic, anti‐inflammatory and anti‐cancer properties. However, few studies on inhibitory effect of B. polyandra on OC have been performed. In the present study, we found that B. polyandra polysaccharides (BPP) induced cell cycle arrest at S phase, triggered apoptosis and inhibited migration and invasion of OC cells. Furthermore, we also found that there was a potential and close relationship between BPP and P53‐mediated pathway. Overall, these findings suggest that BPP can be a potential therapeutic agent for the treatment of OC.  相似文献   
105.
The two subunits (α and β) of pregnant mare serum gonadotropin have been dissociated and partially characterized. Recombination of the biologically inactive subunits results in the restoration of both the follicle stimulating and leuteinizing activities of pregnant mare serum gonadotropin. In addition, the α subunit of pregnant mare serum gonadotropin can be combined with the β subunit of either ovine luteinizing hormone, human chorionic gonadotropin, or follicle stimulating hormone with generation of the specific activity expected of the β subunit.  相似文献   
106.
A dodecapeptide EDIKPKTSLAFR ligand targeting CEN- 1 human nasopharyngeal carcinoma (NPC) was identified by in vivo phage display. Two tridecapeptides and their derivatives, named YR13 (YEDIKPKTSLAFR), EY 1 3 (EDIKPKTSLAFRY), EY 1 3-NH2 (EDIKPKTSLAFRY-NH2) and Fmoc-YR 1 3 (Fmoc-YEDIKPKTSLAFR), were synthesized and radiolabeled with ^[3]I. The stability in vitro, biodistribution and tissue distribution of selected phage particles in mice bearing NPC tumor were determined, and plasma metabolites analysis of radiolabeled peptides was carried out. Although Fmoc and NH2 groups could protect the peptide from deiodination, only Fmoc group inhibited the binding of Fmoc-YR13 to NPC tumors. The compound EY13-NH2, the C-terminal amide of peptide EY13, had the greatest serum stability, the least deiodination, and showed favorable tumor/blood ratios. The selected phage particles (phage 3 or phage 5) were more concentrated in NPC tumors than the control phage (initial phage display peptide library). EY13 could also inhibit the binding of selected phage particles to tumors. The results indicated that EDIKPKTSLAFR was a good candidate in diagnostic and therapeutic NPC.  相似文献   
107.
108.
目的:探讨彩色多普勒超声(CDFI)对乳腺癌新辅助化疗(NCT)疗效评价的临床应用价值。方法:选取2013年1月~2013年12月在我院接受新辅助化疗后行手术治疗的女性乳腺癌患者55例,以病理学评价为金标准,化疗后根据化疗效果分为有效组和无效组,利用CDFI观察患者NCT前后病灶超声指标、病灶内血流分级及阻力指数(RI)值变化。结果:55例患者中,临床触诊疗效评价符合率为36.4%,敏感度为60.7%;CDFI评价符合率为70.9%,敏感度为85.7%。CDFI检查显示,乳腺癌NCT后原发肿瘤病灶大小显著缩小,边界多清晰可见,内部回声及后方回声倾向正常。有效组NCT前后病灶内的血流类型和RI值变化有统计学意义(P0.05),无效组NCT前后病灶内的血流类型和RI值无明显变化(P0.05)。结论:CDFI技术可对乳腺癌NCT前后病灶大小及病灶内部血流动力学变化提供客观参数,是评价乳腺癌NCT疗效的有效方法。  相似文献   
109.
gp190 is a glycoprotein expressed on the cell surface of several human colon carcinoma cells in culture, on epithelial cells of fetal colon, but not on the normal mucosa of adult colon; thus it is referred to as an oncofetal crypt cell antigen. We report the characterisation of O[emsp4 ]-linked glycans carried by gp190 synthesised by [3H]glucosamine-labelled Caco-2 cells at the confluence (undifferentiated cells) and at three weeks of postconfluence (differentiated cells). By using a specific monoclonal antibody, gp190 was isolated and analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The mobility of gp190 from differentiated cells was found to be lower than that from undifferentiated cells, suggesting a more extensive glycosylation process in the former glycoprotein. The major results of the glycan characterisation have been as follows: (i) gp190 carries mainly, if not exclusively, O-linked glycans with the core-2 structure; (ii) the elongation with N-acetyllactosamine units of the Gal1,4GlcNAc1,6(Gal1,3)GalNAc tetrasaccharide predominates in gp190 synthesised by differentiated cells, whereas the direct 2,3sialylation of the tetrasaccharide is prevalent in gp190 synthesised by undifferentiated cells. The increment in the core-2 1,6GlcNAc-transferase activity under the Caco-2 differentiation process may be relevant in producing the larger occurrence of polylactosaminoglycans in gp190 from differentiated cells. Since no change in the activity of the 2,3sialyltransferases upon cell differentiation was observed, we suggest that the lower 2,3sialylation in gp190 synthesised by polarised cells might be due to a changed transit-rate through the distal Golgi apparatus.  相似文献   
110.
口腔鳞癌中D2-40表达的特点及临床意义   总被引:1,自引:0,他引:1  
目的探讨口腔鳞癌组织中淋巴管分布、密度及其与临床病理因素之间的关系。方法应用免疫组化SP法检测口腔癌D2-40的表达情况,计数淋巴管密度(lymphatic vessel density,LVD),分析其与临床病理特征间的关系。结果口腔鳞癌中的淋巴管形态及分布在不同区域具有异质性。与肿瘤中心(肿瘤实质)及癌旁正常组织比较,肿瘤边缘区(肿瘤间质)的淋巴管LVD为(11.09±2.958),显著高于肿瘤中心(5.81±1.334)及癌旁正常组织(4.96±1.716),且形态多呈扩张状态。结论口腔鳞癌中的淋巴管主要位于肿瘤边缘区,肿瘤边缘区LVD与淋巴结转移状态相关,检测口腔癌边缘区的LVD对预测是否发生淋巴结转移可能具有重要意义。  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