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   1415346篇
  免费   97699篇
  国内免费   2304篇
耳鼻咽喉   19971篇
儿科学   46184篇
妇产科学   41119篇
基础医学   206997篇
口腔科学   40206篇
临床医学   116118篇
内科学   282064篇
皮肤病学   30425篇
神经病学   110466篇
特种医学   53474篇
外国民族医学   367篇
外科学   212976篇
综合类   27189篇
现状与发展   1篇
一般理论   321篇
预防医学   108685篇
眼科学   32863篇
药学   108581篇
  1篇
中国医学   3022篇
肿瘤学   74319篇
  2018年   16121篇
  2017年   11611篇
  2016年   12733篇
  2015年   14560篇
  2014年   19309篇
  2013年   29456篇
  2012年   42286篇
  2011年   45217篇
  2010年   25787篇
  2009年   23357篇
  2008年   42505篇
  2007年   45993篇
  2006年   46256篇
  2005年   45157篇
  2004年   43193篇
  2003年   41698篇
  2002年   40925篇
  2001年   61743篇
  2000年   63639篇
  1999年   53792篇
  1998年   14800篇
  1997年   13189篇
  1996年   13419篇
  1995年   12668篇
  1994年   12023篇
  1992年   42714篇
  1991年   41871篇
  1990年   41425篇
  1989年   40014篇
  1988年   37383篇
  1987年   36498篇
  1986年   34915篇
  1985年   33239篇
  1984年   24728篇
  1983年   21488篇
  1982年   12747篇
  1981年   11259篇
  1979年   23621篇
  1978年   16544篇
  1977年   14373篇
  1976年   13585篇
  1975年   14952篇
  1974年   17580篇
  1973年   17029篇
  1972年   16222篇
  1971年   15132篇
  1970年   14045篇
  1969年   13636篇
  1968年   12903篇
  1967年   11292篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
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   
22.
23.
24.
25.
26.
27.
Delayed contrast enhancement after injection of a gadolinium-chelate (Gd-chelate) is a reference imaging method to detect myocardial tissue changes. Its localization within the thickness of the myocardial wall allows differentiating various pathological processes such as myocardial infarction (MI), inflammatory myocarditis, and cardiomyopathies. The aim of the study was first to characterize benign myocarditis using quantitative delayed-enhancement imaging and then to investigate whether the measure of the extracellular volume fraction (ECV) can be used to discriminate between MI and myocarditis.In 6 patients with acute benign myocarditis (32.2 ± 13.8 year-old, subepicardial late gadolinium enhancement [LGE]) and 18 patients with MI (52.3 ± 10.9 year-old, subendocardial/transmural LGE), myocardial T1 was determined using the Modified Look-Locker Imaging (MOLLI) sequence at 3 Tesla before and after Gd-chelate injection. T1 values were compared in LGE and normal regions of the myocardium. The myocardial T1 values were normalized to the T1 of blood, and the ECV was calculated from T1 values of myocardium and blood pre- and post-Gd injection.In both myocarditis and MI, the T1 was lower in LGE regions than in normal regions of the left ventricle. T1 of LGE areas was significantly higher in myocarditis than in MI (446.8 ± 45.8 vs 360.5 ± 66.9 ms, P = 0.003) and ECV was lower in myocarditis than in MI (34.5 ± 3.3 vs 53.8 ± 13.0 %, P = 0.004).Both inflammatory process and chronic fibrosis induce LGE (subepicardial in myocarditis and subendocardial in MI). The present study demonstrates that the determination of T1 and ECV is able to differentiate the 2 histological patterns.Further investigation will indicate whether the severity of ECV changes might help refine the predictive risk of LGE in myocarditis.  相似文献   
28.
29.
30.
The aim of the present study was to evaluate the antimicrobial activity of two synbiotic combinations, Lactobacillus fermentum with short-chain fructooligosaccharides (FOS-LF) and Bifidobacterium longum with isomaltooligosaccharides (IMO-BL), against enterohaemorrhagic Escherichia coli O157:H7 and enteropathogenic E. coli O86. Antimicrobial activity was determined (1) by co-culturing the synbiotics and pathogens in batch cultures, and (2) with the three-stage continuous culture system (gut model), inoculated with faecal slurry from an elderly donor. In the co-culture experiments, IMO-BL was significantly inhibitory to both E. coli strains, while FOS-LF was slightly inhibitory or not inhibitory. Factors other than acid production appeared to play a role in the inhibition. In the gut models, both synbiotics effectively inhibited E. coli O157 in the first vessel, but not in vessels 2 and 3. E. coli O86 was not significantly inhibited.  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