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   2374966篇
  免费   175259篇
  国内免费   3425篇
耳鼻咽喉   33185篇
儿科学   78442篇
妇产科学   67941篇
基础医学   350394篇
口腔科学   67347篇
临床医学   213007篇
内科学   459512篇
皮肤病学   51246篇
神经病学   191322篇
特种医学   91250篇
外国民族医学   602篇
外科学   352715篇
综合类   48561篇
现状与发展   4篇
一般理论   859篇
预防医学   185145篇
眼科学   54191篇
药学   177583篇
  7篇
中国医学   4215篇
肿瘤学   126122篇
  2018年   24921篇
  2017年   19176篇
  2016年   21515篇
  2015年   24209篇
  2014年   32874篇
  2013年   50858篇
  2012年   69195篇
  2011年   74308篇
  2010年   43290篇
  2009年   40453篇
  2008年   71274篇
  2007年   76574篇
  2006年   76651篇
  2005年   75079篇
  2004年   72153篇
  2003年   69647篇
  2002年   68142篇
  2001年   102876篇
  2000年   106068篇
  1999年   88913篇
  1998年   25894篇
  1997年   23176篇
  1996年   23454篇
  1995年   22182篇
  1994年   20908篇
  1993年   19408篇
  1992年   70387篇
  1991年   69373篇
  1990年   68082篇
  1989年   65976篇
  1988年   61459篇
  1987年   60371篇
  1986年   57556篇
  1985年   54917篇
  1984年   41482篇
  1983年   36153篇
  1982年   21790篇
  1981年   19637篇
  1979年   39718篇
  1978年   28581篇
  1977年   24343篇
  1976年   22803篇
  1975年   24834篇
  1974年   29688篇
  1973年   28852篇
  1972年   27365篇
  1971年   25521篇
  1970年   23919篇
  1969年   22844篇
  1968年   21417篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.

Interstitial lung disease (ILD) represents a significant cause of morbidity and mortality in systemic sclerosis (SSc). The purpose of this study was to examine recirculating lymphocytes from SSc patients for potential biomarkers of interstitial lung disease (ILD). Peripheral blood mononuclear cells (PBMCs) were isolated from patients with SSc and healthy controls enrolled in the Vanderbilt University Myositis and Scleroderma Treatment Initiative Center cohort between 9/2017–6/2019. Clinical phenotyping was performed by chart abstraction. Immunophenotyping was performed using both mass cytometry and fluorescence cytometry combined with t-distributed stochastic neighbor embedding analysis and traditional biaxial gating. This study included 34 patients with SSc-ILD, 14 patients without SSc-ILD, and 25 healthy controls. CD21lo/neg cells are significantly increased in SSc-ILD but not in SSc without ILD (15.4 ± 13.3% vs. 5.8 ± 0.9%, p = 0.002) or healthy controls (5.0 ± 0.5%, p < 0.0001). While CD21lo/neg B cells can be identified from a single biaxial gate, tSNE analysis reveals that the biaxial gate is comprised of multiple distinct subsets, all of which are increased in SSc-ILD. CD21lo/neg cells in both healthy controls and SSc-ILD are predominantly tBET positive and do not have intracellular CD21. Immunohistochemistry staining demonstrated that CD21lo/neg B cells diffusely infiltrate the lung parenchyma of an SSc-ILD patient. Additional work is needed to validate this biomarker in larger cohorts and longitudinal studies and to understand the role of these cells in SSc-ILD.

  相似文献   
3.
4.
5.
6.
7.
Journal of Behavioral Medicine - Evidence supports the use of graphic warnings to educate the public about the health harms of smoking and suggests warnings eliciting negative emotional responses...  相似文献   
8.
Noninvasive imaging of cardiac fibrosis is important for early diagnosis and intervention in chronic heart diseases. Here, we investigated whether noninvasive, contrast agent-free MRI T2-mapping can quantify myocardial fibrosis in preclinical models of aging and pressure overload. Myocardial fibrosis and remodeling were analyzed in two animal models: (i) aging (15-month-old male CF-1 mice vs. young 6- to 8-week-old mice), and (ii) pressure overload (PO; by transverse aortic constriction in 4- to 5-month-old male C57BL/6 mice vs. sham-operated for 14 days). In vivo T2-mapping was performed by acquiring data during the isovolumic and early diastolic phases, with a modified respiratory and ECG-triggered multiecho TurboRARE sequence on a 7-T MRI. Cine MRI provided cardiac morphology and function. A quantitative segmentation method was developed to analyze the in vivo T2-maps of hearts at midventricle, apex, and basal regions. The cardiac fibrosis area was analyzed ex vivo by picro sirius red (PSR) staining. Both aged and pressure-overloaded hearts developed significant myocardial contractile dysfunction, cardiac hypertrophy, and interstitial fibrosis. The aged mice had two phenotypes, fibrotic and mild-fibrotic. Notably, the aged fibrotic subgroup and the PO mice showed a marked decrease in T2 relaxation times (25.3 ± 0.6 in aged vs. 29.9 ± 0.7 ms in young mice, p = 0.002; and 24.3 ± 1.7 in PO vs. 28.7 ± 0.7 ms in shams, p = 0.05). However, no significant difference in T2 was detected between the aged mild-fibrotic subgroup and the young mice. Accordingly, an inverse correlation between myocardial fibrosis percentage (FP) and T2 relaxation time was derived (R2 = 0.98): T2 (ms) = 30.45 – 1.05 × FP. Thus, these results demonstrate a statistical agreement between T2-map–quantified fibrosis and PSR staining in two different clinically relevant animal models. In conclusion, T2-mapping MRI is a promising noninvasive contrast agent-free quantitative technique to characterize myocardial fibrosis.  相似文献   
9.
10.
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