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   357374篇
  免费   72645篇
  国内免费   21369篇
耳鼻咽喉   3796篇
儿科学   6803篇
妇产科学   3937篇
基础医学   48066篇
口腔科学   10565篇
临床医学   55867篇
内科学   64453篇
皮肤病学   10231篇
神经病学   29187篇
特种医学   12650篇
外国民族医学   204篇
外科学   40933篇
综合类   47723篇
现状与发展   79篇
一般理论   47篇
预防医学   23135篇
眼科学   9742篇
药学   34518篇
  308篇
中国医学   17517篇
肿瘤学   31627篇
  2024年   943篇
  2023年   5211篇
  2022年   11457篇
  2021年   15982篇
  2020年   16570篇
  2019年   20001篇
  2018年   20474篇
  2017年   20863篇
  2016年   20997篇
  2015年   25108篇
  2014年   28121篇
  2013年   26231篇
  2012年   23624篇
  2011年   26392篇
  2010年   22949篇
  2009年   16813篇
  2008年   16219篇
  2007年   15195篇
  2006年   15491篇
  2005年   15206篇
  2004年   10012篇
  2003年   9909篇
  2002年   8480篇
  2001年   7874篇
  2000年   7829篇
  1999年   7860篇
  1998年   5114篇
  1997年   5149篇
  1996年   4035篇
  1995年   3820篇
  1994年   3112篇
  1993年   2136篇
  1992年   2360篇
  1991年   1943篇
  1990年   1638篇
  1989年   1431篇
  1988年   1208篇
  1987年   1003篇
  1986年   790篇
  1985年   660篇
  1984年   384篇
  1983年   237篇
  1982年   139篇
  1981年   145篇
  1980年   97篇
  1979年   98篇
  1978年   14篇
  1977年   10篇
  1975年   8篇
  1971年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Cantharidin (CTD) is an effective antitumor agent. However, it exhibits significant hepatotoxicity, the mechanism of which remains unclear. In this study, biochemical and histopathological analyses complemented with ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS)-based targeted metabolomic analysis of bile acids (BAs) were employed to investigate CTD-induced hepatotoxicity in rats. Sixteen male and female Sprague–Dawley rats were randomly divided into two groups: control and CTD (1.0 mg/kg) groups. Serum and liver samples were collected after 28 days of intervention. Biochemical, histopathological, and BA metabolomic analyses were performed for all samples. Further, the key biomarkers of CTD-induced hepatotoxicity were identified via multivariate and metabolic pathway analyses. In addition, metabolite–gene–enzyme network and Kyoto Encyclopedia of Genes and Genomes pathway analyses were used to identify the signaling pathways related to CTD-induced hepatotoxicity. The results revealed significantly increased levels of biochemical indices (alanine aminotransferase, aspartate aminotransferase, and total bile acid). Histopathological analysis revealed that the hepatocytes were damaged. Further, 20 endogenous BAs were quantitated via UHPLC-MS/MS, and multivariate and metabolic pathway analyses of BAs revealed that hyocholic acid, cholic acid, and chenodeoxycholic acid were the key biomarkers of CTD-induced hepatotoxicity. Meanwhile, primary and secondary BA biosynthesis and taurine and hypotaurine metabolism were found to be associated with the mechanism by which CTD induced hepatotoxicity in rats. This study provides useful insights for research on the mechanism of CTD-induced hepatotoxicity.  相似文献   
23.
24.
We propose a high order finite difference linear scheme combined with a high order bound preserving maximum-principle-preserving (MPP) flux limiter to solve the incompressible flow system. For such problem with highly oscillatory structure but not strong shocks, our approach seems to be less dissipative and much less costly than a WENO type scheme, and has high resolution due to a Hermite reconstruction. Spurious numerical oscillations can be controlled by the weak MPP flux limiter. Numerical tests are performed for the Vlasov-Poisson system, the 2D guiding-center model and the incompressible Euler system. The comparison between the linear and WENO type schemes, with and without the MPP flux limiter, will demonstrate the good performance of our proposed approach.  相似文献   
25.
宫腔积液指宫腔内液体积存(积水、积血或积脓),是绝经后女性常见体征之一,常于超声检查时发现。持续宫腔积液患者,需宫腔镜检查寻找病因。本文报道1例以宫腔积液为首发症状,经宫腔镜检查确诊为胃型宫颈腺癌的患者。通过病例回顾并文献复习,以期为更多绝经后宫腔积液及宫颈病变的诊断提供参考,避免漏诊及误诊。1病例资料患者67岁,女,主因"绝经18年,不规则阴道出血2月"于2020年5月就诊于首都医科大学附属北京妇产医院妇科微创中心。  相似文献   
26.
Metformin, a drug for type 2 diabetes mellitus, has shown therapeutic effects for various cancers. However, it had no beneficial effects on the survival rate of human malignant mesothelioma (HMM) patients. The present study was performed to elucidate the underlying mechanism of metformin resistance in HMM cells. Glucose‐starved HMM cells had enhanced resistance to metformin, demonstrated by decreased apoptosis and autophagy and increased cell survival. These cells showed abnormalities in mitochondria, such as decreased ATP synthesis, morphological elongation, altered mitochondrial permeability transition pore and hyperpolarization of mitochondrial membrane potential (MMP). Intriguingly, Mdr1 was significantly upregulated in mitochondria but not in cell membrane. The upregulated mitochondrial Mdr1 was reversed by treatment with carbonyl cyanide m‐chlorophenyl hydrazone, an MMP depolarization inducer. Furthermore, apoptosis and autophagy were increased in multidrug resistance protein 1 knockout HMM cells cultured under glucose starvation with metformin treatment. The data suggest that mitochondrial Mdr1 plays a critical role in the chemoresistance to metformin in HMM cells, which could be a potential target for improving its therapeutic efficacy.  相似文献   
27.
Gold nanoparticles (Au NPs) hold great promise in food, industrial and biomedical applications due to their unique physicochemical properties. However, influences of the gastrointestinal tract (GIT), a likely route for Au NPs administration, on the physicochemical properties of Au NPs has been rarely evaluated. Here, we investigated the influence of GIT fluids on the physicochemical properties of Au NPs (5, 50, and 100?nm) and their implications on intestinal epithelial permeability in vitro. Au NPs aggregated in fasted gastric fluids and generated hydroxyl radicals in the presence of H2O2. Cell studies showed that GIT fluids incubation of Au NPs affected the cellular uptake of Au NPs but did not induce cytotoxicity or disturb the intestinal epithelial permeability.  相似文献   
28.
29.
We report a case of benign lymphoplasmacytic plaque (LPP) in a child. These asymptomatic erythematous papulonodular lesions are an emerging clinicopathological entity. Herein, we describe a previously unreported site for LPP lesions, namely, the volar wrist and the distal ipsilateral palm.  相似文献   
30.
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