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   292980篇
  免费   58322篇
  国内免费   11783篇
耳鼻咽喉   3143篇
儿科学   7580篇
妇产科学   3427篇
基础医学   43727篇
口腔科学   8757篇
临床医学   38545篇
内科学   54609篇
皮肤病学   10031篇
神经病学   23218篇
特种医学   8878篇
外国民族医学   77篇
外科学   33900篇
综合类   34957篇
现状与发展   36篇
一般理论   45篇
预防医学   21283篇
眼科学   6438篇
药学   29424篇
  213篇
中国医学   12670篇
肿瘤学   22127篇
  2024年   795篇
  2023年   3236篇
  2022年   8124篇
  2021年   11968篇
  2020年   12524篇
  2019年   16934篇
  2018年   16837篇
  2017年   17631篇
  2016年   17703篇
  2015年   20508篇
  2014年   22977篇
  2013年   23649篇
  2012年   21300篇
  2011年   22186篇
  2010年   21256篇
  2009年   15590篇
  2008年   14714篇
  2007年   13581篇
  2006年   12441篇
  2005年   11000篇
  2004年   8703篇
  2003年   8431篇
  2002年   7249篇
  2001年   5283篇
  2000年   4492篇
  1999年   3566篇
  1998年   2189篇
  1997年   2271篇
  1996年   1639篇
  1995年   1498篇
  1994年   1355篇
  1993年   945篇
  1992年   1154篇
  1991年   1005篇
  1990年   906篇
  1989年   840篇
  1988年   737篇
  1987年   645篇
  1986年   601篇
  1985年   494篇
  1984年   426篇
  1983年   350篇
  1982年   334篇
  1981年   311篇
  1980年   239篇
  1979年   246篇
  1978年   219篇
  1977年   245篇
  1976年   225篇
  1974年   175篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
A pathological feature in atherosclerosis is the dysfunction and death of vascular endothelial cells (EC). Oxidized low‐density lipoprotein (LDL), known to accumulate in the atherosclerotic arterial walls, impairs endothelium‐dependent relaxation and causes EC apoptosis. A major bioactive ingredient of the oxidized LDL is lysophosphatidylcholine (LPC), which at higher concentrations causes apoptosis and necrosis in various EC. There is hitherto no report on LPC‐induced cytotoxicity in brain EC. In this work, we found that LPC caused cytosolic Ca2+ overload, mitochondrial membrane potential decrease, p38 activation, caspase 3 activation and eventually apoptotic death in mouse cerebral bEND.3 EC. In contrast to reported reactive oxygen species (ROS) generation by LPC in other EC, LPC did not trigger ROS formation in bEND.3 cells. Pharmacological inhibition of p38 alleviated LPC‐inflicted cell death. We examined whether heparin could be cytoprotective: although it could not suppress LPC‐triggered Ca2+ signal, p38 activation and mitochondrial membrane potential drop, it did suppress LPC‐induced caspase 3 activation and alleviate LPC‐inflicted cytotoxicity. Our data suggest LPC apoptotic death mechanisms in bEND.3 might involve mitochondrial membrane potential decrease and p38 activation. Heparin is protective against LPC cytotoxicity and might intervene steps between mitochondrial membrane potential drop/p38 activation and caspase 3 activation.  相似文献   
82.
83.
84.
85.
1. To investigate Genkwa Flos hepatotoxicity, a cell metabolomics strategy combined with serum pharmacology was performed on human HL-7702 liver cells in this study.

2. Firstly, cell viability and biochemical indicators were determined and the cell morphology was observed to confirm the cell injury and develop a cell hepatotoxicity model. Then, with the help of cell metabolomics based on UPLC-MS, the Genkwa Flos group samples were completely separated from the blank group samples in the score plots and seven upregulated as well as two down-regulated putative biomarkers in the loading plot were identified and confirmed. Besides, two signal molecules and four enzymes involved in biosynthesis pathway of lysophosphatidylcholine and the sphingosine kinase/sphingosine-1-phosphate pathway were determined to investigate the relationship between Genkwa Flos hepatotoxicity and these two classic pathways. Finally, the metabolic pathways related to specific biomarkers and two classic metabolic pathways were analyzed to explain the possible mechanism of Genkwa Flos hepatotoxicity.

3. Based on the results, lipid peroxidation and oxidative stress, phospholipase A2/lysophosphatidylcholine pathway, the disturbance of sphingosine-1-phosphate metabolic profile centered on sphingosine kinase/sphingosine-1-phosphate pathway and fatty acid metabolism might be critical participators in the progression of liver injury induced by Genkwa Flos.  相似文献   

86.
Neuroscience and Behavioral Physiology - Objective. To determine the frequency, structure, and severity of cognitive impairments in patients with bipolar affective disorder (BAD) in remission....  相似文献   
87.
First described in 1955 in New Jersey, epizootic haemorrhagic disease (EHD) causes a severe clinical disease in wild and domestic ruminants worldwide. Epizootic haemorrhagic disease outbreaks occur in deer populations each year from summer to late autumn. The etiological agent is EHD virus (EHDV) which is a double‐stranded segmented icosahedral RNA virus. EHD virus utilizes point mutations and reassortment strategies to maintain viral fitness during infection. In 2018, EHDV serotype 2 was predominantly detected in deer in Illinois. Whole genome sequencing was conducted for two 2018 EHDV2 isolates (IL41747 and IL42218) and the sequence analyses indicated that IL42218 was a reassortant between different serotypes whereas IL41747 was a genetically stable strain. Our data suggest that multiple strains contribute to outbreaks each year.  相似文献   
88.
89.
目的 通过阿霉素(Dox)复制大鼠慢性心力衰竭(CHF)模型,观察Liguzinediol对CHF大鼠心功能的影响。方法 通过血流动力学观察Liguzinediol对Dox(腹腔注射,2 mg/kg)诱导的CHF大鼠左心室内压最大上升/下降速率(±dp/dtmax)、左心室内压(LVSP)、动脉收缩压(ASP)、动脉舒张压(ADP)和心率(HR)的变化;观察Liguzinediol对血清一氧化氮(NO)、一氧化氮合成酶(NOS)、超氧化物歧化酶(SOD)、肿瘤坏死因子-α(TNF-α)和白细胞介素-6(IL-6)以及血浆中丙二醛(MDA)的影响。结果 Liguzinediol能增加LVSP、+dp/dtmax、ASP、ADP、AP、HR,降低-dp/dtmax(P<0.05~0.01);降低NO、iNOS以及MDA的浓度,同时增强了SOD的活性(P<0.05~0.01);抑制IL-6和TNF-α的生成(P<0.05~0.01)。结论 Liguzinediol可明显改善Dox诱导的CHF大鼠血流动力学指标,减少模型大鼠炎症因子的释放以及抑制氧自由基的生成。   相似文献   
90.
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