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   15324篇
  免费   1519篇
  国内免费   2807篇
  2024年   30篇
  2023年   197篇
  2022年   284篇
  2021年   629篇
  2020年   543篇
  2019年   664篇
  2018年   616篇
  2017年   526篇
  2016年   717篇
  2015年   977篇
  2014年   1184篇
  2013年   1245篇
  2012年   1438篇
  2011年   1368篇
  2010年   995篇
  2009年   878篇
  2008年   1015篇
  2007年   929篇
  2006年   868篇
  2005年   811篇
  2004年   724篇
  2003年   655篇
  2002年   572篇
  2001年   350篇
  2000年   285篇
  1999年   209篇
  1998年   175篇
  1997年   136篇
  1996年   111篇
  1995年   77篇
  1994年   65篇
  1993年   40篇
  1992年   45篇
  1991年   44篇
  1990年   26篇
  1989年   28篇
  1988年   24篇
  1987年   15篇
  1986年   9篇
  1985年   16篇
  1984年   13篇
  1983年   13篇
  1982年   17篇
  1981年   10篇
  1980年   6篇
  1979年   9篇
  1976年   5篇
  1972年   7篇
  1970年   5篇
  1965年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
152.
153.
A series of derivatives of the amine of 9-dihydro-9-O-ethylamino-N-desmethyl-N-isopropyl erythromycin A derivatives were synthesized as motilin agonists. The compounds were developed for potency without showing antibacterial activity and inhibition of the hERG potassium channel. The formamide of the amide series was found to show the optimal combination of properties relative to carbamates, ureas, thioureas, and amines. This prompted an investigation of heterocyclic isosteres for the amide. In this series the triazole had the optimal combination of properties. From the study, two compounds met the criteria for detailed pharmacokinetic studies.  相似文献   
154.
Biomechanics and Modeling in Mechanobiology - The aim of this study was to evaluate the effectiveness of various head injury criteria and associated risk functions in prediction of vulnerable road...  相似文献   
155.
目的:探讨mi R-5195-3p对人宫颈癌细胞系Si Ha增殖、迁移与侵袭的影响。方法:采用qRT-PCR检测人宫颈癌细胞SiHa和正常上皮细胞HaCaT中mi R-5195-3p的表达水平。将mi R-5195-3p mimic转染至Si Ha细胞中构建外源性过表达细胞株,阴性对照组中则转染NC mimic,并用q RT-PCR验证转染效率;通过MTT和集落形成实验检测细胞增殖能力;划痕愈合实验检测细胞横向迁移能力; Transwell小室实验检测细胞纵向迁移能力和侵袭能力;采用qRT-PCR和Western blot检测E-cadherin、Vimentin与snail m RNA转录水平及蛋白表达水平。结果:宫颈癌细胞Si Ha中的mi R-5195-3p表达水平较HaCaT偏低(P 0. 05)。与阴性对照组相比,转染mi R-5195-3p mimic的SiHa细胞中mi R-5195-3p水平显著增高(P 0. 01);并且其体外增殖(P 0. 001),迁移(P 0. 001)与侵袭能力(P 0. 001)明显减弱;同时E-cadherin表达水平上调而Vimentin、snail表达水平下调。结论:过表达mi R-5195-3p可能通过阻碍EMT通路抑制宫颈癌细胞Si Ha的增殖,迁移与侵袭。  相似文献   
156.
Multiplexed single‐cell protein secretion analysis provides an in‐depth understanding of cellular heterogeneity in intercellular communications mediated by secreted proteins in both fundamental and clinical research. However, it has been challenging to increase the proteomic parameters co‐profiled from every single cell in a facile way. Herein, a simple method to improve the multiplexed proteomic parameters of PDMS microwell based single‐cell secretion analysis platform by sandwiching PDMS stencil in between two antibody‐coated glass slides is introduced. Two different antibody panels can be immobilized easily by static coating, without using sophisticated fluid handling or bulky equipment. 5‐plexed, 3‐fluorescence color single‐cell secretion assay is demonstrated with this platform to investigate human monocytic U937 cells in response to lipopolysaccharide and phorbol myristate acetate stimulation, which identified the existence of functional subsets dictated by different cytokine profiles. The technology introduced here is simple, easy to operate, which holds great potential to become a powerful tool for profiling multiplexed single‐cell cytokine secretion at high throughput to dissect cellular heterogeneity in secretome signatures.  相似文献   
157.
158.
Oral squamous cell carcinoma (OSCC) is the most common malignant tumour in the oral and maxillofacial region. Numerous cancers share ten common traits (“hallmarks”) that govern the transformation of normal cells into cancer cells. Long non‐coding RNAs (lncRNAs) are important factors that contribute to tumorigenesis. However, very little is known about the cooperative relationships between lncRNAs and cancer hallmark‐associated genes in OSCC. Through integrative analysis of cancer hallmarks, somatic mutations, copy number variants (CNVs) and expression, some OSCC‐specific cancer hallmark‐associated genes and lncRNAs are identified. A computational framework to identify gene and lncRNA cooperative regulation pairs (GLCRPs) associated with different cancer hallmarks is developed based on the co‐expression and co‐occurrence of mutations. The distinct and common features of ten cancer hallmarks based on GLCRPs are characterized in OSCC. Cancer hallmark insensitivity to antigrowth signals and self‐sufficiency in growth signals are shared by most GLCRPs in OSCC. Some key GLCRPs participate in many cancer hallmarks in OSCC. Cancer hallmark‐associated GLCRP networks have complex patterns and specific functions in OSCC. Specially, some key GLCRPs are associated with the prognosis of OSCC patients. In summary, we generate a comprehensive landscape of cancer hallmark‐associated GLCRPs that can act as a starting point for future functional explorations, the identification of biomarkers and lncRNA‐based targeted therapy in OSCC.  相似文献   
159.
Vascular endothelial growth factor (VEGF) is a well‐known angiogenic factor, however its ability in promoting therapeutic angiogenesis following myocardial infarction (MI) is limited. Here, we aimed to investigate whether dual treatment with insulin‐like growth factor binding protein‐4 (IGFBP‐4), an agent that protects against early oxidative damage, can be effective in enhancing the therapeutic effect of VEGF following MI. Combined treatment with IGFBP‐4 enhanced VEGF‐induced angiogenesis and prevented cell damage via enhancing the expression of a key angiogenic factor angiopoietin‐1. Dual treatment with the two agents synergistically decreased cardiac fibrosis markers collagen‐I and collagen‐III following MI. Importantly, while the protective action of IGFBP‐4 occurs at an early stage of ischemic injury, the action of VEGF occurs at a later stage, at the onset angiogenesis. Our findings demonstrate that VEGF treatment alone is often not enough to protect against oxidative stress and promote post‐ischemic angiogenesis, whereas the combined treatment with IGFBP4 and VEGF can utilize the dual roles of these agents to effectively protect against ischemic and oxidative injury, and promote angiogenesis. These findings provide important insights into the roles of these agents in the clinical setting, and suggest new strategies in the treatment of ischemic heart disease.  相似文献   
160.
This study aimed to explore new therapeutic targets to improve the survival rate of patients with oral squamous cell carcinoma (OSCC).MiR-210-3p, EphrinA3 and EMT related indices were evaluated in OSCC tissues and cell lines. In addition, the relationship between differential EphrinA3 expression and tumour progression was explored through molecular biology techniques, in vitro functional experiments and tumour xenotransplantation models. The expression of EphrinA3 (rs = −0.719, P < .05) and E-cadherin (rs = −0.856, P < .05) was negatively correlated with the pathological grading in OSCC tissues. Protein clustering shows EphrinA3 may be associated with tumour progression. EphrinA3 also can regulate the biological behaviour of oral cancer cells. And it regulates the EMT by the PI3K/AKT signalling pathway. MiR-210-3p targeted the gen EFNA3. Up-regulation of miR-210-3p expression can decrease the expression of EphrinA3 and further to influence the biological behaviour of OSCC. The miR-210-3p-EphrinA3-PI3K/AKT signalling axis plays an important role in the progress of OSCC. EphrinA3 may serve as a novel target for oral cancer treatment.  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