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   3158篇
  免费   174篇
  国内免费   4篇
耳鼻咽喉   59篇
儿科学   257篇
妇产科学   41篇
基础医学   384篇
口腔科学   42篇
临床医学   197篇
内科学   640篇
皮肤病学   100篇
神经病学   169篇
特种医学   74篇
外科学   485篇
综合类   99篇
预防医学   148篇
眼科学   126篇
药学   295篇
中国医学   14篇
肿瘤学   206篇
  2023年   27篇
  2022年   39篇
  2021年   102篇
  2020年   51篇
  2019年   58篇
  2018年   89篇
  2017年   54篇
  2016年   59篇
  2015年   57篇
  2014年   101篇
  2013年   112篇
  2012年   223篇
  2011年   219篇
  2010年   109篇
  2009年   74篇
  2008年   136篇
  2007年   136篇
  2006年   134篇
  2005年   116篇
  2004年   108篇
  2003年   85篇
  2002年   78篇
  2001年   75篇
  2000年   53篇
  1999年   68篇
  1998年   21篇
  1997年   21篇
  1995年   23篇
  1993年   24篇
  1992年   79篇
  1991年   56篇
  1990年   48篇
  1989年   54篇
  1988年   44篇
  1987年   38篇
  1986年   53篇
  1985年   38篇
  1984年   34篇
  1983年   21篇
  1979年   33篇
  1977年   20篇
  1976年   33篇
  1975年   21篇
  1974年   19篇
  1973年   20篇
  1972年   21篇
  1971年   23篇
  1970年   31篇
  1969年   27篇
  1967年   19篇
排序方式: 共有3336条查询结果,搜索用时 15 毫秒
91.
92.
Efforts to understand the nature of “Not Just Right Experiences” (NJREs) have expanded the scientific understanding of obsessive–compulsive (OC) behavior. Approximately 80 % of unselected adults report experiencing NJREs and these experiences have been found to highly correlate with OC behavior. The purpose of this study was to assess NJREs in an unselected sample of adolescents (ages 14–17; N = 152), to compare their experience with adults (N = 237), and to assess the relation between NJREs and OC symptoms. Findings from questionnaires completed on the Internet were consistent with previous findings in adults, 81 % of adolescents endorsed recently having an NJRE. Some reactions differed according to age: adults reported NJREs as more frequent and adolescents endorsed feeling more compelled to respond. Surprisingly, OC symptoms were not significantly related to NJREs in the adolescents. Implications, limitations, and future directions for the study of NJREs in youth are discussed.  相似文献   
93.
A 30-d course of oral administration of a semipurified extract of the root of Withania somnifera consisting predominantly of withanolides and withanosides reversed behavioral deficits, plaque pathology, accumulation of β-amyloid peptides (Aβ) and oligomers in the brains of middle-aged and old APP/PS1 Alzheimer's disease transgenic mice. It was similarly effective in reversing behavioral deficits and plaque load in APPSwInd mice (line J20). The temporal sequence involved an increase in plasma Aβ and a decrease in brain Aβ monomer after 7 d, indicating increased transport of Aβ from the brain to the periphery. Enhanced expression of low-density lipoprotein receptor-related protein (LRP) in brain microvessels and the Aβ-degrading protease neprilysin (NEP) occurred 14-21 d after a substantial decrease in brain Aβ levels. However, significant increase in liver LRP and NEP occurred much earlier, at 7 d, and were accompanied by a rise in plasma sLRP, a peripheral sink for brain Aβ. In WT mice, the extract induced liver, but not brain, LRP and NEP and decreased plasma and brain Aβ, indicating that increase in liver LRP and sLRP occurring independent of Aβ concentration could result in clearance of Aβ. Selective down-regulation of liver LRP, but not NEP, abrogated the therapeutic effects of the extract. The remarkable therapeutic effect of W. somnifera mediated through up-regulation of liver LRP indicates that targeting the periphery offers a unique mechanism for Aβ clearance and reverses the behavioral deficits and pathology seen in Alzheimer's disease models.  相似文献   
94.
95.
Tey SK  Khanna R 《Blood》2012,120(5):994-1004
The endogenous presentation of the majority of viral epitopes through MHC class I pathway is strictly dependent on the transporter associated with antigen processing (TAP) complex, which transfers the peptide products of proteasomal degradation into the endoplasmic reticulum. A small number of epitopes can be presented through the TAP-independent pathway, the precise mechanism for which remains largely unresolved. Here we show that TAP-independent presentation can be mediated by autophagy and that this process uses the vacuolar pathway and not the conventional secretory pathway. After macroautophagy, the antigen is processed through a proteasome-independent pathway, and the peptide epitopes are loaded within the autophagolysosomal compartment in a process facilitated by the relative acid stability of the peptide-MHC interaction. Despite bypassing much of the conventional MHC class I pathway, the autophagy-mediated pathway generates the same epitope as that generated through the conventional pathway and thus may have a role in circumventing viral immune evasion strategies that primarily target the conventional pathway.  相似文献   
96.
In selected patients, transcatheter closure of atrial septal defects with the AMPLATZER Septal Occluder has yielded excellent results. However, there is a slight risk of device embolization after deployment. We report the case of a 26-year-old woman in whom an embolized AMPLATZER device was retrieved percutaneously from the right pulmonary artery. We also discuss important technical principles for managing this uncommon but potentially severe complication.Key words: Device removal/methods, embolization, therapeutic/instrumentation, heart catheterization/instrumentation, heart septal defects, atrial/ultrasonography, patient selection, prosthesis implantation/adverse effects, prostheses and implants, septal occluder device/adverse effects, treatment outcomeTranscatheter closure of atrial septal defects (ASDs) with use of the AMPLATZER® Septal Occluder (St. Jude Medical, Inc.; St. Paul, Minn) has yielded excellent results in properly selected patients.1,2 The major advantage of the AMPLATZER occluder is its easy retrieval at all stages of deployment before its final release from the delivery cable. Although embolization of AMPLATZER ASD occluders is rare, it can occur even when interventional cardiologists are experienced. Despite an earlier belief that the transcatheter retrieval of embolized AMPLATZER devices would be difficult, success rates from 50% to 75% have been reported.3,4 We describe the retrieval of an embolized AMPLATZER device in a young woman. In addition, we present some technical principles with which operators practicing device closure should be familiar.  相似文献   
97.
98.
99.
100.
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