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   109312篇
  免费   11554篇
  国内免费   6103篇
耳鼻咽喉   845篇
儿科学   1063篇
妇产科学   1550篇
基础医学   29808篇
口腔科学   4990篇
临床医学   7037篇
内科学   14577篇
皮肤病学   2020篇
神经病学   7626篇
特种医学   2134篇
外国民族医学   26篇
外科学   8872篇
综合类   16550篇
现状与发展   23篇
一般理论   2篇
预防医学   2952篇
眼科学   3593篇
药学   10740篇
  18篇
中国医学   3226篇
肿瘤学   9317篇
  2024年   61篇
  2023年   1251篇
  2022年   1731篇
  2021年   3315篇
  2020年   3370篇
  2019年   2995篇
  2018年   3087篇
  2017年   3627篇
  2016年   4173篇
  2015年   4660篇
  2014年   6997篇
  2013年   8641篇
  2012年   6741篇
  2011年   7797篇
  2010年   6338篇
  2009年   6041篇
  2008年   6390篇
  2007年   6295篇
  2006年   5810篇
  2005年   4972篇
  2004年   4241篇
  2003年   3473篇
  2002年   2649篇
  2001年   2246篇
  2000年   1945篇
  1999年   1618篇
  1998年   1388篇
  1997年   1321篇
  1996年   1146篇
  1995年   1365篇
  1994年   1218篇
  1993年   1087篇
  1992年   888篇
  1991年   862篇
  1990年   727篇
  1989年   707篇
  1988年   609篇
  1987年   545篇
  1986年   473篇
  1985年   712篇
  1984年   635篇
  1983年   434篇
  1982年   540篇
  1981年   416篇
  1980年   352篇
  1979年   312篇
  1978年   216篇
  1977年   167篇
  1976年   148篇
  1975年   56篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
31.
32.
《Immunity》2022,55(7):1234-1249.e6
  1. Download : Download high-res image (215KB)
  2. Download : Download full-size image
  相似文献   
33.
Ochratoxin A (OTA) is a mycotoxin that mainly causes nephrotoxicity. The single nephrotoxicity of OTA exposure on glomeruli or renal tubule had been well documented, however, the comparison toxicity between it is still unclear. Here, C57BL/6 mice and two types of nephrocyte were treated with concentration-gradient OTA to explore its differentiation nephrotoxicity. Results showed that OTA induced nephrotoxicity in vivo and in vitro, manifested as the deteriorative kidney function in mice and the cut-down cell viability in nephrocyte. Besides, results of murine kidney pathological section and IC50 of two types nephrocyte indicated that OTA-induced toxicity in renal tubule was higher than its in glomeruli. In addition, OTA exposure induced autophagy signaling differentiation expression. It revealed that autophagy was implicated in OTA-induced differential nephrotoxicity in glomeruli and renal tubule. Altogether, we proved that OTA induces a differentiation nephrotoxicity in glomeruli and renal tubule, and it is related to autophagy differential regulation.  相似文献   
34.
Cyanidin-3-glucoside (C3G) is a well-known natural anthocyanin with antioxidant and anti-inflammatory properties. In this study, we explored the role and action mechanism of C3G in high glucose (HG)-induced damage of human nucleus pulposus cells (HNPCs). Cell viability was assessed by CCK-8 assay. TUNEL assay was performed for detecting apoptotic rate. Western blot was performed to determine the expression levels of cl-caspase-3, caspase-3, Bax, Bim, collagen II, aggrecan, MMP-3, MMP-13, and ADAMTS5. Reactive oxygen species (ROS) generation was analyzed using DCFH-DA staining. The Nrf2 was knocked down or overexpressed in HNPCs through transfection with si-Nrf2 or pcDNA3.0-Nrf2. C3G treatment (12.5, 25, and 50 μM) improved cell viability of HNPCs under HG condition. HG-induced cell apoptosis of HNPCs was attenuated by C3G with decreased apoptotic rate and relative levels of cl-caspase-3/caspase-3, Bax, and Bim. C3G treatment caused significant increase in expression levels of collagen II and aggrecan and decrease in the relative levels of MMP-3, MMP-13, and ADAMTS5. After treatment with C3G, ROS generation in HNPCs was markedly reduced. Treatment with N-acetylcysteine (NAC) reversed HG-induced cell apoptosis and extracellular matrix (ECM) degradation. C3G treatment induced the expression of Nrf2 and HO-1 in HG-induced HNPCs. Moreover, knockdown of Nrf2 reversed the inhibitory effect of C3G on ROS production. Summarily, C3G exerted a protective effect on ROS-mediated cellular damage in HNPCs under HG condition, which was attributed to the induction of the Nrf2/HO-1 signaling pathway.  相似文献   
35.
Hepatitis E virus (HEV) is the most common cause of acute liver failure (LF) and one of the most common factors causing acute injury in acute-on-chronic LF (ACLF). When HEV-related LF occurs, a series of changes take place in both the intrahepatic environment and extrahepatic microenvironment. The changed types and distribution of immune cells (infiltrating macrophages and increased lymphocytes) in liver tissue, as well the increased proinflammatory cytokines and chemokines in the blood, indicate that the occurrence and progression of HEV-related LF are closely related to immune imbalance. The clinical features and immune reaction in the body during HEV-related acute LF (ALF) and ACLF are complicated. This review highlights recent progress in elucidating the clinical manifestations of HEV-associated ALF and ACLF and discusses the corresponding systemic immune changes and possible regulatory mechanisms.  相似文献   
36.
37.
《Dental materials》2022,38(8):1283-1300
ObjectivesTo compare new bone formation in mandibular critical-sized bone defects (CSBDs) in healthy, diabetic, osteoporotic, and diabetic-osteoporotic rats filled with bioceramics (BCs) with or without bone marrow mesenchymal stem cells (BMSCs).MethodsA total of 64 adult female Sprague-Dawley rats were randomized into four groups (n = 16 per group): Group 1 healthy, Group 2 diabetic, Group 3 osteoporotic, and Group 4 diabetic-osteoporotic rats. Streptozotocin was used to induce type 1 diabetes in Group 2 and 4, while bilateral ovariectomy was used to induce osteoporosis in Group 3 and 4. The central portion of the rat mandibular symphysis was used as a physiological CSBD. In each group, eight defects were filled with BC (hydroxypatatite 60% and β-tricalcium phosphate 40%) alone and eight with BMSCs cultured on BC. The animals were sacrificed at 4 and 8 weeks, and the mandibles were processed for micro-computed tomography to analyze radiological union and bone mineral density (BMD); histological analysis of the bone union; and immunohistochemical analysis, which included immunoreactivity of vascular endothelial growth factor (VEGF) and bone morphogenetic protein 2 (BMP-2).ResultsIn all groups (healthy, diabetics, osteoporotics, and diabetics-osteoporotics), the CSBDs filled with BC + BMSCs showed greater radiological bone union, BMD, histological bone union, and more VEGF and BMP-2 positivity, in comparison with CSBDs treated with BC alone (at 4 and 8 weeks).ConclusionsApplication of BMSCs cultured on BCs improves bone regeneration in CSBDs compared with application of BCs alone in healthy, diabetic, osteoporotic, and diabetic-osteoporotic rats.  相似文献   
38.
ObjectivesTo determine the anti-inflammatory effects of green tea catechins in immortalized human gingival epithelial cells (Ca9-22) stimulated with Porphyromonas gulae lipopolysaccharide (LPS).MethodsCa9-22 cells were incubated with P. gulae LPS (10 μg/ml) with or without green tea catechins, epigallocatechin-3-gallate (EGCg), epigallocatechin (EGC), epicatechin-3-gallate (ECG), and epicatechin (EC) (each at 50 μM), for 6 or 24 h. Real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay were used to determine the induction of cyclooxygenase 2 (COX2), tumor necrosis factor alpha (TNF-ɑ), interleukin 6 (IL-6), and IL-8. Furthermore, the expression of toll-like receptors (TLRs) 2 and 4 was examined using real-time PCR and western blotting analysis, and phosphorylation of the p38 and ERK1/2 was examined using western blotting analysis.ResultsAt the mRNA and protein levels, EGCg, EGC, ECG, and EC were found to significantly inhibit COX2, TNF-ɑ, IL-6, and IL-8. Furthermore, the levels of ERK1/2 and p38 phosphorylation induced by P. gulae LPS were decreased following the addition of each of the catechins, as well as TLR2 and 4 mRNA and protein.ConclusionsThese findings indicate that green tea catechins are potent inhibitors of in?ammatory responses induced by P. gulae LPS, and may also be useful for prevention and/or attenuation of periodontitis.  相似文献   
39.
40.
目的 探讨扶正化瘀方含药血清对肝星状细胞(HSC)激活素A(activinA)/smad信号通路活化的影响。方法 20只SD大鼠按照随机数字表法分为对照组及扶正化瘀(Fzhy)-低、中、高剂量含药血清组,每组5只,分别以蒸馏水,0.75、1.5、3.0 g/kg扶正化瘀溶液(扶正化瘀胶囊药物粉末与蒸馏水配制)灌胃1次/d,连续3 d,取血制备空白血清(对照组)和含药血清。以大鼠HSC-T6细胞为研究对象,分别用5%、10%、20%体积分数的各组含药血清培养细胞。CCK-8检测细胞存活率,选取细胞存活率在50%左右的体积分数重新分为对照组及Fzhy-低、中、高剂量组。流式细胞术检测细胞周期及凋亡率、线粒体膜电位变化和活性氧(ROS)水平;实时荧光定量聚合酶链反应检测细胞中activinA、smad3、samd7、核因子(NF)-κB的mRNA水平;蛋白质印迹法检测细胞中activinⅡA受体(ActRⅡA)、smad3、NF-κB p65、胱天蛋白酶(caspase)-3的蛋白水平。结果 各扶正化瘀含药血清组的细胞存活率均低于对照组(P<0.05),选择体积分数为10%的含药血清进行后续实验。对照组和各扶正化瘀方含药血清组细胞周期和凋亡率差异均无统计学意义。对照组及Fzhy-低、中、高剂量组细胞内ROS水平及线粒体膜电位水平降低比例逐次升高(P<0.05)。与对照组比较,Fzhy-中、高剂量组smad3 mRNA表达水平降低,smad7 mRNA升高,Fzhy-低、中、高剂量组NF-κB、activinA mRNA,smad3、NF-κB p65、ActRⅡA蛋白表达水平降低,Fzhy-低剂量组、中剂量组caspase-3蛋白表达水平升高(P<0.05);与Fzhy-低剂量组相比,Fzhy-中、高剂量组smad3 mRNA表达水平降低,Fzhy-中剂量组activinA及smad7 mRNA升高(P<0.05)。结论 扶正化瘀方含药血清可通过影响HSC-T6细胞增殖、参与细胞的氧化应激以及调节细胞activinA/smad信号转导通路来实现抗纤维化作用。  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