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   8864篇
  免费   1568篇
  国内免费   529篇
耳鼻咽喉   22篇
儿科学   83篇
妇产科学   90篇
基础医学   2072篇
口腔科学   242篇
临床医学   507篇
内科学   1650篇
皮肤病学   108篇
神经病学   658篇
特种医学   74篇
外国民族医学   2篇
外科学   632篇
综合类   1043篇
现状与发展   2篇
预防医学   224篇
眼科学   128篇
药学   1190篇
  3篇
中国医学   794篇
肿瘤学   1437篇
  2024年   117篇
  2023年   395篇
  2022年   740篇
  2021年   955篇
  2020年   726篇
  2019年   560篇
  2018年   525篇
  2017年   510篇
  2016年   582篇
  2015年   661篇
  2014年   786篇
  2013年   827篇
  2012年   541篇
  2011年   535篇
  2010年   437篇
  2009年   461篇
  2008年   399篇
  2007年   293篇
  2006年   221篇
  2005年   165篇
  2004年   141篇
  2003年   96篇
  2002年   67篇
  2001年   56篇
  2000年   32篇
  1999年   34篇
  1998年   25篇
  1997年   17篇
  1996年   22篇
  1995年   9篇
  1994年   7篇
  1993年   3篇
  1992年   4篇
  1991年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1986年   2篇
  1982年   1篇
  1981年   1篇
  1977年   2篇
  1973年   1篇
  1971年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
赵慧梅  唐志书  全心雨  宋忠兴  王梅  张珍 《中草药》2024,55(13):4423-4433
目的 探究五味沙棘散对卵清蛋白(ovalbumin,OVA)诱导的过敏性哮喘大鼠的保护作用及机制。方法 SD大鼠随机分为对照组、模型组、地塞米松(0.5 mg/kg)组和五味沙棘散(0.5、2.0 g/kg)组,建立OVA诱导的大鼠早期支气管哮喘模型,苏木素-伊红(HE)和Masson染色观察支气管病理情况及纤维化程度;免疫组化检测支气管间隙连接蛋白43(connexin 43,Cx43)的表达和分布;ELISA检测血清中免疫球蛋白E(immunoglobulin E,IgE)和白细胞介素-13(interleukin-13,IL-13)水平;亚甲基蓝法和WSP-1荧光探针法测定血清中硫化氢(hydrogen sulfide,H2S)水平。建立CdCl2诱导的支气管上皮BEAS-2B细胞损伤模型,MTT法检测细胞活性;Hoechest 33342染色法观察细胞核形态变化;MitoSOX染色检测细胞线粒体活性氧(mitochondrial reactive oxygen species,mtROS)水平;Western blotting检测半胱氨酸天冬氨酸蛋白酶-3(cystein-asparate protease-3,Caspase-3)、核因子红细胞系2相关因子(nuclear factor erythroid 2-related factor,Nrf2)和Kelch样ECH关联蛋白1(Kelch like ECH associated protein 1,Keap1)蛋白表达。结果 五味沙棘散能够减少支气管黏膜上皮细胞脱落和黏液分泌(P<0.001),降低胶原纤维的沉积和Cx43的表达及分布(P<0.05、0.01、0.001),降低血清中IgE、IL-13水平(P<0.05),升高血清中H2S水平(P<0.05、0.01)。五味沙棘散含药血清呈剂量相关性地抑制CdCl2诱导的BEAS-2B细胞凋亡及mtROS水平(P<0.01、0.001),上调Caspase-3和Nrf2蛋白表达(P<0.05、0.01),下调Keap1蛋白表达(P<0.01)。结论 五味沙棘散对OVA诱导的哮喘大鼠和CdCl2诱导的支气管上皮细胞凋亡均具有保护作用,其机制可能与调控Nrf2/Keap1信号通路有关。  相似文献   
22.
BackgroundLINC00941 has been proved to be related to various tumors, but its relationship with laryngocarcinoma remains vague.MethodsLINC00941 expression in laryngocarcinoma tumor and laryngocarcinoma cells was determined by real time‐quantitative polymerase chain reaction (RT‐qPCR). Besides, the five‐year survival of laryngocarcinoma patients with different LINC00941 expression was analyzed with Kaplan–Meier survival analysis, and the clinical characteristics of laryngocarcinoma patients were also recorded. After transfection, cell viability, cell proliferation, apoptosis, cell cycle, migration, and invasion were detected by cell counting kit‐8 (CCK‐8), colony formation, flow cytometry, cell scratch, and Transwell assays, respectively. Glycolysis was assessed by the colorimetric method. Expressions of proliferation‐associated proteins, migration‐associated proteins, glycolysis‐associated proteins, and phosphatidylinositol 3‐kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signal pathway‐associated proteins were detected by Western blot.ResultsIn laryngocarcinoma tumor tissues and cells, LINC00941 was highly expressed. High expression of LINC00941 decreased the 5‐year survival of laryngocarcinoma patients, and it was positively related to lymph node metastasis and clinical stages. LINC00941 overexpression decreased apoptosis but promoted cell viability, proliferation, cell‐cycle progression, migration, and invasion, and glucose consumption and lactate production in laryngocarcinoma cells. Moreover, LINC00941 overexpression elevated expressions of Ki‐67, PCNA, MMP2, N‐Cadherin, HK2, PFKFB4, and PKM, activated the PI3K/AKT/mTOR signal pathway but reduced E‐Cadherin expression, while LINC00941 silencing had the opposite effects. PKM overexpression reversed the effects of LINC00941 silencing on cellular and glycolytic phenotypes.ConclusionLINC00941 promoted in vitro progression and glycolysis of laryngocarcinoma cells by upregulating PKM via activating the PI3K/AKT/mTOR signaling pathway.  相似文献   
23.
Introduction: Abnormal deposition of α-synuclein (ASN) is a hallmark and possible central mechanism of Parkinson’s disease and other synucleinopathies. Their therapy is currently hampered by the lack of early, screening-compatible diagnostic methods and efficient treatments.

Areas covered: Patent applications related to synucleinopathies obtained from Patentscope and Espacenet databases are described against the background of current knowledge regarding the regulatory mechanisms of ASN behavior including alternative splicing, post-translational modifications, molecular interactions, aggregation, degradation, and changes in localization.

Expert opinion: As the central pathological feature and possibly one of root causes in a number of neurodegenerative diseases, deregulation of ASN is a potentially optimal diagnostic and therapeutic target. Changes in total ASN may have diagnostic value, especially if non-invasive /peripheral tissue tests can be developed. Targeting the whole ASN pool for therapeutic purposes may be problematic, however. ASN mutations, truncation, and post-translational modifications have great potential value; therapeutic approaches selective towards aggregated or aggregation-prone ASN forms may lead to more successful and safe treatments. Numerous ASN interactions with signaling pathways, protein degradation and stress mechanisms widen its potential therapeutic significance dramatically. However, significant improvement in the basic knowledge on ASN is necessary to fully exploit these opportunities.  相似文献   

24.
目的研究不同类型先天性肛门直肠畸形(ARM)胎鼠直肠末端肠神经系统(ENS)发育程度,探讨SHH/BMP4在其发育过程中的作用。方法利用全反式维甲酸(ATRA)诱导大鼠产生肛门直肠畸形胚胎,孕20d剖宫取胎,应用免疫组织化学方法检测对照组和高、低位ARM组直肠末端神经元特异性烯醇化酶(NSE)及骨形态发生蛋白4(BMP4)的表达;反转录-聚合酶链反应(RT-PCR)方法检测各组直肠末端SHH/BMP4mRNA的表达差异。结果对照组肠壁肌间及黏膜下神经丛可见NSE和BMP4抗体染色阳性细胞,ARM高位组与ARM低位组、对照组比较,阳性细胞的平均光密度(MOD)值明显降低,差异均有统计学意义(P<0.05);ARM低位组和对照组相比,阳性细胞的MOD值略降低,差异有统计学意义(P<0.05)。在ARM直肠末端SHH和BMP4基因表达呈正相关(P<0.01,r=0.884),对照组与ARM组相比较,BMP4和SHHmRNA的表达水平明显高于ARM组,差异均有统计学意义(P<0.05),不同ARM组之间比较,高位ARM组的表达水平显著减弱低于低位ARM组,差异也有统计学意义(P<0.05)。结论①不同类型ARM胎鼠直肠末端ENS发育程度存在差异,不仅与闭锁的位置密切相关,还可能与BMP4基因的表达水平有关。②过量的ATRA可能抑制了SHH/BMP4信号表达,干扰了直肠ENS的正常发育。  相似文献   
25.
目的 建立SD大鼠后囊膜混浊(posterior capsular opacification,PCO)动物模型,检测Rho/Rock通路中的关键因子RhoA、Rho激酶Ⅰ(Rho associated coiledcoil forming protein kinase-Ⅰ,Rock Ⅰ)和肌球蛋白轻链(phosphorylated myosin light chain,p-MLC)在PCO中的表达.探讨Rho/Rock通路在PCO形成过程中的作用.方法 选用健康SD大鼠30只,随机分为对照组(0d)和实验组(3d、7d、14 d、28 d),每个时间点各6只.所有大鼠(右眼)均行晶状体囊外摘出术,显微镜下观察不同时间点术眼前节的炎症反应及PCO发生情况.ELISA法检测不同时间点房水中TGF-β的表达.处死大鼠后摘除眼球行组织病理学检查,免疫组织化学和Western Blot法检测RhoA、Rock Ⅰ、p-MLC在晶状体后囊上的表达.结果 随着术后观察时间的推移,PCO混浊程度逐渐增加,HE染色显示晶状体上皮细胞不同程度的增生、移行.对照组术后0d、3d、7d、14 d、28 d房水中TGF-β的表达量分别为(37.28±1.31)μg·L-1、(40.29±3.17) μg·L-1、(42.12±3.45) μg·L-1、(60.42±4.75) μg·L-1、(68.69±8.06)μg·L-1,实验组各时间点与对照组相比,差异有统计学意义(F=137.158,P<0.05);不同时间点两两相比,差异均有统计学意义(均为P<0.05).术后0d、3d、7d、14 d和28 d晶状体后囊膜上RhoA蛋白相对表达量(RhoA/GAPDH)分别为1.00±0.00、1.49±0.01、1.57±0.03、1.77±0.02和1.97±0.02,实验组各时间点与对照组相比,差异有统计学意义(F=94.546,P<0.05);不同时间点两两相比,差异均有统计学意义(均为P<0.05).Rock Ⅰ蛋白的表达量(Rock Ⅰ/GAPDH)分别为1.00±0.00、0.35±0.12、1.42 ±0.14、1.78±0.09和1.95±0.14,实验组各时间点与对照组相比,差异有统计学意义(F=30.942,P<0.05);不同时间点两两相比,差异均有统计学意义(均为P<0.05).p-MLC蛋白的相对表达量(p-MLC/GAPDH)分别为1.00±0.00、1.44±0.08、1.47±0.13、1.63±0.10和2.12±0.20,实验组各时间点与对照组相比,差异有统计学意义(F =34.313,P<0.05);不同时间点两两相比,差异均有统计学意义(均为P<0.05).结论 RhoA、Rock Ⅰ、p-MLC在PCO形成过程中表达逐渐增多,Rho/Rock信号转导通路可能与PCO的发生、发展有关.  相似文献   
26.
BACKGROUNDHepatocellular carcinoma (HCC) exhibits high invasiveness and mortality rates, and the molecular mechanisms of HCC have gained increasing research interest. The abnormal DNA damage response has long been recognized as one of the important factors for tumor occurrence and development. Recent studies have shown the potential of the protein RING finger and WD repeat domain 3 (RFWD3) that positively regulates p53 stability in response to DNA damage as a therapeutic target in cancers. AIMTo investigate the relationship between HCC and RFWD3 in vitro and in vivo and explored the underlying molecular signalling transduction pathways. METHODS RFWD3 gene expression was analyzed in HCC tissues and adjacent normal tissues. Lentivirus was used to stably knockdown RFWD3 expression in HCC cell lines. After verifying the silencing efficiency, Celigo/cell cycle/apoptosis and MTT assays were used to evaluate cell proliferation and apoptosis. Subsequently, cell migration and invasion were assessed by wound healing and transwell assays. In addition, transduced cells were implanted subcutaneously and injected into the tail vein of nude mice to observe tumor growth and metastasis. Next, we used lentiviral-mediated rescue of RFWD3 shRNA to verify the phenotype. Finally, the microarray, ingenuity pathway analysis, and western blot analysis were used to analyze the regulatory network underlying HCC. RESULTSCompared with adjacent tissues, RFWD3 expression levels were significantly higher in clinical HCC tissues and correlated with tumor size and TNM stage (P < 0.05), which indicated a poor prognosis state. RFWD3 silencing in BEL-7404 and HCC-LM3 cells increased apoptosis, decreased growth, and inhibited the migration in shRNAi cells compared with those in shCtrl cells (P < 0.05). Furthermore, the in vitro results were supported by the findings of the in vivo experiments with the reduction of tumor cell invasion and migration. Moreover, the rescue of RFWD3 shRNAi resulted in the resumption of invasion and metastasis in HCC cell lines. Finally, gene expression profiling and subsequent experimental verification revealed that RFWD3 might influence the proliferation and metastasis of HCC via the Wnt/β-catenin signalling pathway.CONCLUSIONWe provide evidence for the expression and function of RFWD3 in HCC. RFWD3 affects the prognosis, proliferation, invasion, and metastasis of HCC by regulating the Wnt/β-catenin signalling pathway.  相似文献   
27.
目的从PI3K/AKT信号通路研究三七总皂苷(panax notoginseng saponins,PNS)预防糖尿病大血管病变的机制。方法雄性SD大鼠分为对照组、模型组和治疗组,模型组和治疗组大鼠高脂饲料喂养6周后给予链脲佐菌素单次腹腔注射(30 mg·kg-1体质量)建立2型糖尿病模型,成模后治疗组给予PNS灌胃干预(100mg·kg-1体质量)。血糖仪检测大鼠空腹尾静脉血糖(FBG),ELISA法测定血清空腹胰岛素(FINS)和糖化血红蛋白(GHbA1c)水平,苏木素-伊红(HE)染色观察腹主动脉病理形态改变,荧光定量PCR检测腹主动脉标记物MMP2、MMP9、CD34、VEGF及PI3K、AKT mRNA相对表达,Western Blot法观察PI3K和AKT蛋白表达情况。结果模型组和治疗组大鼠在STZ注射造模后,FBG均显著高于对照组(P<0.01和P<0.01),两组间差异无统计学意义(P>0.05)。模型组和治疗组血清INS均显著高于对照组(P<0.01和P<0.01),治疗组INS显著低于模型组(P<0.05)。HE染色显示,与对照组比较,模型组动脉壁变薄,平滑肌细胞增多,排列紊乱,内膜不光滑;治疗组较模型组明显改善。模型组MMP2、MMP9表达较对照组显著上调(P<0.05和P<0.01),治疗组MMP9较模型组显著下调(P<0.01)。模型组CD34、VEGF表达较对照组显著上调(P<0.05和P<0.01),治疗组CD34较模型组显著下调(P<0.05)。模型组大鼠PI3K表达较对照组显著上调(P<0.05),治疗组PI3K表达较模型组显著下调(P<0.05)。模型组PI3K蛋白、p-AKT蛋白表达均显著高于对照组(P<0.01和P<0.01),治疗组PI3K、p-AKT均显著低于对照组(P<0.01和P<0.05),模型组p-AKT/AKT显著高于对照组(P<0.05),治疗组p-AKT/AKT较模型组有显著降低趋势,且与对照组差异无统计学意义。结论PNS可能通过下调PI3K/AKT信号通路预防糖尿病大血管病变。  相似文献   
28.
In this study, we aimed to evaluate the effect of Nobiletin (NOB) on the placenta of Sprague–Dawley (SD) rats that had undergone reduced uterine perfusion pressure (RUPP) surgery and to evaluate the safety of NOB intervention during pregnancy. The results showed that NOB alleviated placental hypoxia, attenuated placental cell apoptosis, and inhibited placental damage in RUPP rats. No side effect of NOB intervention during pregnancy was observed. BeWo cell lines with P53 knockdown were then constructed using lentiviral transfection, and the P53 signaling pathway was found to be essential for NOB to reduce hypoxia-induced apoptosis of the BeWo cell lines. In summary, NOB attenuated hypoxia-induced placental damage by regulating the P53 signaling pathway, and those findings may contribute some insights into the role of NOB in placental development and the prevention of placental-related diseases.  相似文献   
29.
30.
Background miR1555p is associated with autoimmune diseases. T helper 17 (Th17) cells, interleukin (IL)‐17, and suppressor of cytokines signaling 1 (SOCS1) have important roles in the pathogenesis of systemic sclerosis (SSc). The purpose of this study was to explore the role of miR1555p in the regulation of IL‐17 and SOCS1 expression in Th17 cells and the subsequent effect on SSc disease progression.MethodsTh17 cells were isolated from peripheral blood mononuclear cells of SSc patients and healthy controls (HCs). RT‐qPCR and western blotting were used to examine the expression patterns of miR1555p, IL‐17, and SOCS1. Luciferase reporter assays were performed to confirm SOCS1 as a target of miR1555p. RNA pull‐down assays were performed to detect the interaction of IL‐17 and SOCS1 with miR1555p. In situ hybridization was performed to analyze the co‐expression pattern of miR1555p and IL17A in Th17 cells.ResultsThe levels of Th17 cell‐derived miR1555p were significantly up‐regulated in SSc patients compared with HCs, and its levels were negatively correlated with SOCS1 levels. Meanwhile, miR1555p positively regulated IL‐17 expression levels in Th17 cells isolated from SSc patients as the disease progressed. Using pmirGLO vectors, SOCS1 was confirmed as a target of miR1555p. The binding status of IL17 and SOCS1 to miR1555p was related to SSc progression. An increase in the co‐localization of miR1555p and IL‐17 was associated with greater SSc progression.ConclusionsIL‐17 and SOCS1 expression modulated by Th17 cell‐derived miR1555p are critical for SSc progression, which may provide novel insights into the pathogenesis of SSc.  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