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   3344902篇
  免费   229114篇
  国内免费   8691篇
耳鼻咽喉   46305篇
儿科学   111276篇
妇产科学   92452篇
基础医学   470542篇
口腔科学   92448篇
临床医学   302853篇
内科学   648253篇
皮肤病学   80529篇
神经病学   271292篇
特种医学   130029篇
外国民族医学   933篇
外科学   499810篇
综合类   66214篇
现状与发展   6篇
一般理论   1195篇
预防医学   250360篇
眼科学   76360篇
药学   249717篇
  13篇
中国医学   7296篇
肿瘤学   184824篇
  2021年   25500篇
  2019年   26218篇
  2018年   37675篇
  2017年   29211篇
  2016年   34016篇
  2015年   38120篇
  2014年   51617篇
  2013年   77192篇
  2012年   103611篇
  2011年   109209篇
  2010年   65605篇
  2009年   62204篇
  2008年   101883篇
  2007年   108789篇
  2006年   110626篇
  2005年   106529篇
  2004年   102238篇
  2003年   98688篇
  2002年   95281篇
  2001年   161325篇
  2000年   165283篇
  1999年   139249篇
  1998年   39523篇
  1997年   35006篇
  1996年   35088篇
  1995年   33869篇
  1994年   30839篇
  1993年   28923篇
  1992年   107184篇
  1991年   103203篇
  1990年   100387篇
  1989年   97112篇
  1988年   88702篇
  1987年   86675篇
  1986年   81522篇
  1985年   77590篇
  1984年   57606篇
  1983年   48559篇
  1982年   28617篇
  1979年   51158篇
  1978年   35706篇
  1977年   30937篇
  1976年   28126篇
  1975年   30602篇
  1974年   35856篇
  1973年   34241篇
  1972年   32344篇
  1971年   30080篇
  1970年   27666篇
  1969年   26657篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Individuals with sudden unilateral deafness offer a unique opportunity to study plasticity of the binaural auditory system in adult humans. Stimulation of the intact ear results in increased activity in the auditory cortex. However, there are no reports of changes at sub-cortical levels in humans. Therefore, the aim of the present study was to investigate changes in sub-cortical activity immediately before and after the onset of surgically induced unilateral deafness in adult humans. Click-evoked auditory brainstem responses (ABRs) to stimulation of the healthy ear were recorded from ten adults during the course of translabyrinthine surgery for the removal of a unilateral acoustic neuroma. This surgical technique always results in abrupt deafferentation of the affected ear. The results revealed a rapid (within minutes) reduction in latency of wave V (mean pre = 6.55 ms; mean post = 6.15 ms; p < 0.001). A latency reduction was also observed for wave III (mean pre = 4.40 ms; mean post = 4.13 ms; p < 0.001). These reductions in response latency are consistent with functional changes including disinhibition or/and more rapid intra-cellular signalling affecting binaurally sensitive neurons in the central auditory system. The results are highly relevant for improved understanding of putative physiological mechanisms underlying perceptual disorders such as tinnitus and hyperacusis.  相似文献   
4.
5.
6.
Abstract

Objective: To understand the origin of extremely high gonadotropin levels in a perimenopausal woman.

Methods: A 52-year-old woman with a 2?months of amenorrhea followed spontaneous menstrual cycles recovery was referred to our outpatient clinic with elevated follicle-stimulating hormone (FSH, 483 mUI/ml), luteinizing hormone (LH, 475 mUI/ml) and prolactin (PRL, 173?ng/ml). She was known to take levosulpiride. The gonadotropin levels did not fit with the clinical features.

Results: A gonadotroph tumor was ruled out. Further analysis confirmed constantly high FSH, LH and PRL levels. The measurements were repeated using different analytical platforms with different results. After serial dilutions, nonlinearity was present suggesting an immunoassay interference. After post-polyethylene glycol recovery, hormone levels appeared in the normal range. Anti-goat antibodies were recognized in the serum of the patient.

Conclusions: This case report shows a case of falsely abnormal high gonadotropin and PRL levels in a woman during menopause transition. In the clinical practice the evaluation of gonadotropin profile is not recommended at this age, but the abnormal levels stimulated further evaluation. An interference in the assay due to anti-goat antibodies resulted in abnormally high level of FSH and LH. A strict collaboration between clinicians and the laboratory is needed, when laboratory findings do not correspond to clinical findings.  相似文献   
7.
8.
9.

Background

Limited data exists demonstrating the efficacy of minimally invasive surgery (MIS) compared to median sternotomy (MS) for multiple valvular disease (MVD). This systematic review and meta-analysis aims to compare operative and peri-operative outcomes of MIS vs MS in MVD.

Methods

PubMed, Ovid, and Embase were searched from inception until August 2019 for randomized and observational studies comparing MIS and MS in patients with MVD. Clinical outcomes of intra- and postoperative times, reoperation for bleeding and surgical site infection were evaluated.

Results

Five observational studies comparing 340 MIS vs 414 MS patients were eligible for qualitative and quantitative review. The quality of evidence assessed using the Newcastle-Ottawa scale was good for all included studies. Meta-analysis demonstrated increased cardiopulmonary bypass time for MIS patients (weighted mean difference [WMD], 0.487; 95% confidence interval [CI], 0.365-0.608; P < .0001). Similarly, aortic cross-clamp time was longer in patients undergoing MIS (WMD, 0.632; 95% CI, 0.509-0.755; P < .0001). No differences were found in operative mortality, reoperation for bleeding, surgical site infection, or hospital stay.

Conclusions

MIS for MVD have similar short-term outcomes compared to MS. This adds value to the use of minimally invasive methods for multivalvular surgery, despite conferring longer operative times. However, the paucity in literature and learning curve associated with MIS warrants further evidence, ideally randomized control trials, to support these findings.
  相似文献   
10.
ABSTRACT

Objective

To investigate primary care physician clinical practice patterns, barriers, and education surrounding pediatric physical activity (PA), and to compare practice patterns by discipline.  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