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   20135篇
  免费   1378篇
  国内免费   739篇
耳鼻咽喉   20篇
儿科学   946篇
妇产科学   182篇
基础医学   1431篇
口腔科学   23篇
临床医学   1967篇
内科学   4089篇
皮肤病学   26篇
神经病学   2162篇
特种医学   1146篇
外国民族医学   9篇
外科学   1767篇
综合类   3718篇
现状与发展   3篇
预防医学   838篇
眼科学   26篇
药学   1958篇
  7篇
中国医学   1028篇
肿瘤学   906篇
  2024年   34篇
  2023年   260篇
  2022年   468篇
  2021年   689篇
  2020年   621篇
  2019年   596篇
  2018年   576篇
  2017年   722篇
  2016年   726篇
  2015年   697篇
  2014年   1248篇
  2013年   1276篇
  2012年   1213篇
  2011年   1291篇
  2010年   992篇
  2009年   1104篇
  2008年   1042篇
  2007年   1102篇
  2006年   1028篇
  2005年   815篇
  2004年   640篇
  2003年   629篇
  2002年   529篇
  2001年   461篇
  2000年   422篇
  1999年   313篇
  1998年   297篇
  1997年   285篇
  1996年   273篇
  1995年   223篇
  1994年   223篇
  1993年   172篇
  1992年   153篇
  1991年   170篇
  1990年   99篇
  1989年   111篇
  1988年   100篇
  1987年   68篇
  1986年   78篇
  1985年   87篇
  1984年   68篇
  1983年   38篇
  1982年   47篇
  1981年   46篇
  1980年   51篇
  1979年   36篇
  1978年   23篇
  1977年   31篇
  1976年   18篇
  1975年   19篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
PurposeThe purpose of this study was to make a systematic review and meta-analysis to determine the stent diameter (8 mm vs. 10 mm) that conveys better safety and clinical efficacy for transjugular intrahepatic portosystemic shunt (TIPS).Materials and methodsFour databases were used to identify clinical trials published from inception until March 2020. Data were extracted to estimate and compare one-year and three-year overall survivals, hepatic encephalopathy, variceal rebleeding, and shunt dysfunction rates between patients with 8 mm covered stents and those with 10 mm covered stents.ResultsFive eligible studies were selected, which included 489 patients (316 men, 173 women). The 8 mm covered stent group had higher efficacy regarding one-year or three-year overall survival (odds ratio [OR], 2.88; P = 0.003) and (OR, 1.81; P = 0.04) and lower hepatic encephalopathy (OR, 0.69; P = 0.04) compared with 10 mm covered stent group. There were no significant differences in variceal rebleeding rate (OR 0.80; P = 0.67). However, shunt dysfunction was lower in 10 mm covered stent group (OR, 2.26; P = 0.003).ConclusionsOur results suggest that the use of 8 mm covered stents should be preferred to that of 10 mm covered stents for TIPS placement when portal pressure is frequently monitored.  相似文献   
2.
3.
目的:探讨MR对PRES的临床诊断价值。方法应用3.0 T MR对30例PRES患者进行常规扫描,其中19例同时行MRA检查,13例行MRV检查。结果 PRES病变主要累及顶枕叶,双侧基本对称;病变主要位于脑白质内,也可累及其它部位。PRES病变的特点是呈长T 1长T 2信号,边缘不清,无明显占位效应。MRA及MRV均无异常发现。结论 MR对PRES可以作出准确诊断,对临床有重要的指导意义。  相似文献   
4.
5.
6.
7.
8.
《Clinical therapeutics》2019,41(5):836-847
PurposeA role for the immune system in causing myalgic encephalopathy/chronic fatigue syndrome (ME/CFS) is long suspected, but few studies have looked for specific autoantibodies that might contribute to the symptoms. Our aim was to look for evidence of antibodies to neuronal proteins in patients with ME/CSF.MethodsSera samples from 50 patients and 50 healthy individuals were sent coded to the Neuroimmunology Laboratory in Oxford. Screening for antibody binding to neuronal tissue was performed on brain tissue and neuronal cultures. Specific serum antibodies were assessed by antigen-specific cell-based assays and radioimmunoassays. After antibody testing, the associations between seropositive status and clinical data were investigated.FindingsOverall, 8 patients and 11 participants were found to have some serum immunoreactivity toward neuronal or neuromuscular junction proteins, but only 1 patient and 2 participants had specific serum antibodies. Nevertheless, seropositive status in patients with ME was associated with shorter duration since onset and a more severe disease.ImplicationsThe results indicate no overall increased frequency of antibodies to neuronal proteins in ME/CSF and no evidence of a specific antibody that might be causative or contribute to clinical features in patients. However, the association of seropositive status with shorter duration of disease and more severe symptoms suggests a possible role of antibodies at onset in some patients and should be the focus of future studies.  相似文献   
9.
Accurately predicting the hepatic clearance of compounds using in vitro to in vivo extrapolation (IVIVE) is crucial within the pharmaceutical industry. However, several groups have recently highlighted the serious error in the process. Although empirical or regression-based scaling factors may be used to mitigate the common underprediction, they provide unsatisfying solutions because the reasoning behind the underlying error has yet to be determined. One previously noted trend was intrinsic clearance-dependent underprediction, highlighting the limitations of current in vitro systems. When applying these generated in vitro intrinsic clearance values during drug development and making first-in-human dose predictions for new chemical entities though, hepatic clearance is the parameter that must be estimated using a model of hepatic disposition, such as the well-stirred model. Here, we examine error across hepatic clearance ranges and find a similar hepatic clearance-dependent trend, with high clearance compounds not predicted to be so, demonstrating another gap in the field.  相似文献   
10.
INTRODUCTIONThis study aimed to investigate the therapeutic response to injected human umbilical cord blood mesenchymal stem cells (UCBMSCs) among albino rats with streptozotocin (STZ)-induced diabetes mellitus.METHODSControl group (GI; n = 25) rats were fed with standard rat diet. Rats with STZ-induced diabetes mellitus without (GII; n = 25) and with (GIII; n = 25) differentiated human UCBMSCs implantation were the test groups. Rats were sacrificed in Week 11 following implantation. Liver biopsies were sectioned and stained in order to highlight both the presence and function of impregnated cells in the liver tissue.RESULTSHaematoxylin and eosin-stained sections in GI and GII rats showed normal liver architecture while GIII rats showed presence of cell clusters inside the liver tissue and around the central veins. Cell clusters with blue cytoplasm were present in sections in GIII rats but absent in GI and GII rats, indicating the presence of injected differentiated human UCBMSCs. The anti-human insulin immunostaining of GIII rats showed clusters of cells within the liver parenchyma and around central veins, indicating that these cells were active and secreting insulin.CONCLUSIONUCBMSCs are proficient in differentiating into insulin-producing cells in vivo under specific conditions and, when transplanted into the liver of albino rats with STZ-induced diabetes mellitus, were able to secrete insulin and partially control the status of diabetes mellitus in rats.  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