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   5120989篇
  免费   405989篇
  国内免费   16697篇
耳鼻咽喉   72599篇
儿科学   161279篇
妇产科学   135901篇
基础医学   763186篇
口腔科学   145263篇
临床医学   468905篇
内科学   935128篇
皮肤病学   120199篇
神经病学   426371篇
特种医学   200872篇
外国民族医学   1104篇
外科学   774403篇
综合类   149454篇
现状与发展   24篇
一般理论   2841篇
预防医学   428827篇
眼科学   123768篇
药学   365797篇
  32篇
中国医学   14012篇
肿瘤学   253710篇
  2021年   57079篇
  2019年   59683篇
  2018年   76539篇
  2017年   58606篇
  2016年   65256篇
  2015年   77745篇
  2014年   112719篇
  2013年   178530篇
  2012年   144170篇
  2011年   152292篇
  2010年   132112篇
  2009年   131816篇
  2008年   137960篇
  2007年   148181篇
  2006年   155398篇
  2005年   150216篇
  2004年   150447篇
  2003年   139776篇
  2002年   129599篇
  2001年   203188篇
  2000年   201031篇
  1999年   180115篇
  1998年   77341篇
  1997年   71793篇
  1996年   69507篇
  1995年   65333篇
  1994年   59277篇
  1993年   54862篇
  1992年   134477篇
  1991年   129391篇
  1990年   123828篇
  1989年   120621篇
  1988年   111591篇
  1987年   109516篇
  1986年   103722篇
  1985年   100915篇
  1984年   81928篇
  1983年   72033篇
  1982年   53353篇
  1981年   49384篇
  1980年   46228篇
  1979年   72692篇
  1978年   56323篇
  1977年   49554篇
  1976年   46057篇
  1975年   46413篇
  1974年   53398篇
  1973年   51223篇
  1972年   48059篇
  1971年   44194篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.

The exercise pressor reflex is a feedback mechanism engaged upon stimulation of mechano- and metabosensitive skeletal muscle afferents. Activation of these afferents elicits a reflex increase in heart rate, blood pressure, and ventilation in an intensity-dependent manner. Consequently, the exercise pressor reflex has been postulated to be one of the principal mediators of the cardiorespiratory responses to exercise. In this updated review, we will discuss classical and recent advancements in our understating of the exercise pressor reflex function in both human and animal models. Particular attention will be paid to the afferent mechanisms and pathways involved during its activation, its effects on different target organs, its potential role in the abnormal cardiovascular response to exercise in diseased states, and the impact of age and biological sex on these responses. Finally, we will highlight some unanswered questions in the literature that may inspire future investigations in the field.

  相似文献   
22.
23.
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   
24.
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   
25.
26.
Collagens are the most abundant proteins in the extracellular matrix. They provide a framework to build organs and tissues and give structural support to make them resistant to mechanical load and forces. Several intra‐ and extracellular modifications are needed to make functional collagen molecules, intracellular post‐translational modifications of proline and lysine residues having key roles in this. In this article, we provide a review on the enzymes responsible for the proline and lysine modifications, that is collagen prolyl 4‐hydroxylases, 3‐hydroxylases and lysyl hydroxylases, and discuss their biological functions and involvement in diseases.  相似文献   
27.
28.
29.
30.
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