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   3432871篇
  免费   241436篇
  国内免费   9402篇
耳鼻咽喉   48411篇
儿科学   111509篇
妇产科学   97284篇
基础医学   482015篇
口腔科学   97239篇
临床医学   308648篇
内科学   670308篇
皮肤病学   81724篇
神经病学   280134篇
特种医学   132834篇
外国民族医学   1122篇
外科学   516782篇
综合类   72790篇
现状与发展   11篇
一般理论   1301篇
预防医学   256994篇
眼科学   79177篇
药学   252633篇
  12篇
中国医学   7128篇
肿瘤学   185653篇
  2018年   36054篇
  2017年   27998篇
  2016年   32203篇
  2015年   36239篇
  2014年   50134篇
  2013年   75657篇
  2012年   99883篇
  2011年   105807篇
  2010年   63827篇
  2009年   61186篇
  2008年   99479篇
  2007年   106458篇
  2006年   108036篇
  2005年   103901篇
  2004年   100344篇
  2003年   97171篇
  2002年   94073篇
  2001年   160911篇
  2000年   164975篇
  1999年   139555篇
  1998年   40193篇
  1997年   35841篇
  1996年   35481篇
  1995年   34239篇
  1994年   31572篇
  1993年   29610篇
  1992年   109098篇
  1991年   105337篇
  1990年   102357篇
  1989年   99273篇
  1988年   91578篇
  1987年   89832篇
  1986年   84855篇
  1985年   81094篇
  1984年   60775篇
  1983年   51636篇
  1982年   30938篇
  1981年   27716篇
  1979年   55262篇
  1978年   39261篇
  1977年   33848篇
  1976年   31037篇
  1975年   34035篇
  1974年   40116篇
  1973年   38504篇
  1972年   36384篇
  1971年   33958篇
  1970年   31667篇
  1969年   30547篇
  1968年   28350篇
排序方式: 共有10000条查询结果,搜索用时 0 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.
7.
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   
8.
9.
10.

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   
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