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   65695篇
  免费   4740篇
  国内免费   341篇
耳鼻咽喉   666篇
儿科学   1680篇
妇产科学   1633篇
基础医学   8066篇
口腔科学   1582篇
临床医学   6540篇
内科学   14885篇
皮肤病学   914篇
神经病学   5145篇
特种医学   2025篇
外国民族医学   3篇
外科学   10171篇
综合类   1050篇
现状与发展   1篇
一般理论   105篇
预防医学   5444篇
眼科学   1890篇
药学   4622篇
中国医学   162篇
肿瘤学   4192篇
  2023年   317篇
  2022年   556篇
  2021年   1259篇
  2020年   781篇
  2019年   1076篇
  2018年   1353篇
  2017年   909篇
  2016年   1040篇
  2015年   1204篇
  2014年   1869篇
  2013年   2926篇
  2012年   3949篇
  2011年   4294篇
  2010年   2442篇
  2009年   2272篇
  2008年   4141篇
  2007年   4296篇
  2006年   4150篇
  2005年   4209篇
  2004年   3944篇
  2003年   3532篇
  2002年   3497篇
  2001年   795篇
  2000年   661篇
  1999年   760篇
  1998年   758篇
  1997年   621篇
  1996年   510篇
  1995年   496篇
  1994年   474篇
  1993年   455篇
  1992年   555篇
  1991年   522篇
  1990年   427篇
  1989年   459篇
  1988年   409篇
  1987年   389篇
  1986年   372篇
  1985年   426篇
  1984年   438篇
  1983年   400篇
  1982年   531篇
  1981年   446篇
  1980年   489篇
  1979年   311篇
  1978年   326篇
  1977年   325篇
  1976年   264篇
  1975年   294篇
  1974年   249篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
This report describes different imaging techniques of the esophagus in four patients during radiofrequency catheter ablation of atrial fibrillation in the left atrium. A novel use of a mixture of barium cream and gadolinium diglutamate allowed esophageal imaging during magnetic resonance angiography of the left atrium and pulmonary veins. Barium cream used during computer tomography angiographic imaging of the left atrium and pulmonary veins allowed esophageal imaging. The esophagus was also imaged with an electroanatomic mapping system. Esophageal and left atrial imaging helped to avoid catheter ablation in left atrial tissue overlapping the esophagus.  相似文献   
992.
Antibodies to Epstein-Barr virus associated cell membrane antigens persisted or slowly decreased during prolonged uncomplicated survival of patients with Burkitt's lymphoma in remission. Serum was sampled from four patients within 6 months before recurrence occurring after the first year and preceded by remission during more than 6 months. Rapid and significant decreases of the antibodies before clinical recognition of the recurrences were found in three patients. The fourth patient had slowly increasing titers before relapse. Immune stimulant treatment during remission, with BCG (Bacille Calmette Guérin vaccine) or BCG + Bordetella pertussis, temporarily increased the antibody levels. Possible mechanisms for the observed titer changes before recurrence are discussed.  相似文献   
993.
Few data are available on measurements of serum concentrations of complement proteins in inflammatory bowel disease (IBD). Therefore we measured serum levels of C3, C4, and C1-esterase inhibitor (C1-INH) as well as C-reactive protein (CRP) in 167 patients with Crohn's disease (CD) and 111 patients with ulcerative colitis (UC). Median serum concentrations of C3 and C1-INH were significantly higher in CD than in UC. According to multiple logistic regression analysis adjusted to age, sex, activity of disease, and presence of extraintestinal manifestations, IBD patients with high-normal (128%, 75th percentile ) C1-INH concentrations had significantly (0.0275) higher odds ratio to have a diagnosis of CD than UC. Patients with high-normal C3 (1.40 g/liter) and high (20 mg/liter) CRP concentrations had an even higher odds ratio of a CD diagnosis (P = 0.0132). Our findings indicate that measurement of C3, C1-INH, and CRP can be used as an additional marker to pANCA/ASCA for distinguishing patients with CD and UC.  相似文献   
994.
995.
996.
997.
The burden of senescent cells (SnCs), which do not divide but are metabolically active and resistant to death by apoptosis, is increased in older adults and those with chronic diseases. These individuals are also at the greatest risk for morbidity and mortality from SARS-CoV-2 infection. SARS-CoV-2 complications include cytokine storm and multiorgan failure mediated by the same factors as often produced by SnCs through their senescence-associated secretory phenotype (SASP). The SASP can be amplified by infection-related pathogen-associated molecular profile factors. Senolytic agents, such as Fisetin, selectively eliminate SnCs and delay, prevent, or alleviate multiple disorders in aged experimental animals and animal models of human chronic diseases, including obesity, diabetes, and respiratory diseases. Senolytics are now in clinical trials for multiple conditions linked to SnCs, including frailty; obesity/diabetes; osteoporosis; and cardiovascular, kidney, and lung diseases, which are also risk factors for SARS-CoV-2 morbidity and mortality. A clinical trial is underway to test if senolytics decrease SARS-CoV-2 progression and morbidity in hospitalized older adults. We describe here a National Institutes of Health-funded, multicenter, placebo-controlled clinical trial of Fisetin for older adult skilled nursing facility (SNF) residents who have been, or become, SARS-CoV-2 rtPCR-positive, including the rationale for targeting fundamental aging mechanisms in such patients. We consider logistic challenges of conducting trials in long-term care settings in the SARS-CoV-2 era, including restricted access, consent procedures, methods for obtaining biospecimens and clinical data, staffing, investigational product administration issues, and potential solutions for these challenges. We propose developing a national network of SNFs engaged in interventional clinical trials.  相似文献   
998.
999.
1000.

Background:

Major depressive disorder has been associated with abnormal resting-state functional connectivity (FC), especially in cognitive processing and emotional regulation networks. Although studies have found abnormal FC in regions of the default mode network (DMN), no study has investigated the FC of specific regions within the anterior DMN based on cytoarchitectonic subdivisions of the antero-medial pre-frontal cortex (PFC). Studies from different areas in the field have shown regions within the anterior DMN to be involved in emotional intelligence. Although abnormalities in this region have been observed in depression, the relationship between the ventromedial PFC (vmPFC) function and emotional intelligence has yet to be investigated in depressed individuals.

Methods:

Twenty-one medication-free, non–treatment resistant, depressed patients and 21 healthy controls underwent a resting state functional magnetic resonance imaging session. The participants also completed an ability-based measure of emotional intelligence: the Mayer-Salovey-Caruso Emotional Intelligence Test. FC maps of Brodmann areas (BA) 25, 10m, 10r, and 10p were created and compared between the two groups.

Results:

Mixed-effects analyses showed that the more anterior seeds encompassed larger areas of the DMN. Compared to healthy controls, depressed patients had significantly lower connectivity between BA10p and the right insula and between BA25 and the perigenual anterior cingulate cortex. Exploratory analyses showed an association between vmPFC connectivity and emotional intelligence.

Conclusions:

These results suggest that individuals with depression have reduced FC between antero-medial PFC regions and regions involved in emotional regulation compared to control subjects. Moreover, vmPFC functional connectivity appears linked to emotional intelligence.  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