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   4356篇
  免费   236篇
  国内免费   55篇
耳鼻咽喉   14篇
儿科学   67篇
妇产科学   81篇
基础医学   500篇
口腔科学   64篇
临床医学   323篇
内科学   1469篇
皮肤病学   70篇
神经病学   507篇
特种医学   201篇
外科学   610篇
综合类   20篇
预防医学   117篇
眼科学   44篇
药学   224篇
中国医学   23篇
肿瘤学   313篇
  2023年   33篇
  2022年   73篇
  2021年   120篇
  2020年   88篇
  2019年   96篇
  2018年   136篇
  2017年   111篇
  2016年   128篇
  2015年   134篇
  2014年   188篇
  2013年   264篇
  2012年   363篇
  2011年   349篇
  2010年   212篇
  2009年   202篇
  2008年   295篇
  2007年   284篇
  2006年   261篇
  2005年   306篇
  2004年   261篇
  2003年   193篇
  2002年   162篇
  2001年   27篇
  2000年   20篇
  1999年   27篇
  1998年   23篇
  1997年   29篇
  1996年   25篇
  1995年   26篇
  1994年   14篇
  1993年   10篇
  1992年   14篇
  1991年   20篇
  1990年   18篇
  1989年   12篇
  1988年   23篇
  1987年   5篇
  1986年   7篇
  1985年   8篇
  1984年   12篇
  1982年   6篇
  1981年   9篇
  1980年   4篇
  1979年   5篇
  1974年   4篇
  1973年   3篇
  1970年   4篇
  1969年   5篇
  1966年   4篇
  1965年   3篇
排序方式: 共有4647条查询结果,搜索用时 15 毫秒
61.
The mechanical properties of deep fasciae strongly affect muscular actions, development of pathologies, such as acute and chronic compartment syndromes, and the choice of the various fascial flaps. Actually, a clear knowledge of the mechanical characterization of these tissues still lacks. This study focuses attention on experimental tests of different regions of human crural fascia taken from an adult frozen donor. Tensile tests along proximal–distal and medial–lateral direction at a strain rate of 120 %/s were performed at the purpose of evaluating elastic properties. Viscous phenomena were investigated by applying incremental relaxation tests at total strain of 7, 9 and 11 % and observing stress decay for a time interval of 240 s. The elastic response showed that the fascia in the anterior compartment is stiffer than in the posterior compartment, both along the proximal–distal and medial–lateral directions. This result can explain why the compartment syndromes are more frequent in this compartment with respect to posterior one. Furthermore, the fascia is stiffer along the proximal–distal than along medial–lateral direction. This means that the crural fascia can adapt to the muscular variation of volume in a transversal direction, while along the main axis it could be considered as a structure that contributes to transmitting the muscular forces at a distance and connecting the different segments of the limb. The stress relaxation tests showed that the crural fascia needs 120 s to decrease stress of 40 %, suggesting a similar time also in the living so that the static stretching could have an effect on the fascia.  相似文献   
62.
63.
64.
65.
66.
The design of a multitarget and multifunctional small molecule containing two functional groups reacting through different mechanisms represents an attractive goal for the medicinal chemist. The preparation of two bifunctional oxiranylmethyloxy anthraquinones, previously investigated as anticancer agents, is described here. These compounds combine a planar, DNA‐intercalating and pro‐oxidant anthraquinone scaffold and the alkylating epoxide functions which can covalently react with the nucleic acid. Their multilevel molecular reactivity was studied through a combination of analytical techniques: The DNA‐binding properties were investigated using a mass spectrometry‐based binding assay and by nuclear magnetic resonance, highlighting the formation of a covalent adduct with a nucleobase. Moreover, the contribution of the pro‐oxidant redox cycling was evaluated.  相似文献   
67.
Cardiotrophin-1 (CT-1) is a member of the interleukin (IL-6) family of cytokines. Plasma CT-1 levels correlate with the left ventricle mass index in patients with dilatated cardiomyopathy and congestive heart failure (CHF). The aim of this paper was to evaluate CT-1 plasma levels, before and after cardiac resynchronization therapy CRT, and to characterizeits prognostic role in patients with CHF. Fifty-two consecutive patients (M/F = 39/13; 56 ± 11 years old) underwent clinical and echocardiographic evaluation, and blood sample collection at baseline. The same evaluation was repeated 6.4 ± 0.79 months after CRT. Patients with a decreased LV end-systolic volume by at least 15% (reverse remodeling) were considered echo responders to CRT. Twenty-nine patients (56%) were responders to CRT. After CRT, only 15 patients (29%) showed increased CT-1 after CRT. They were all non responders to CRT. A multivariate, logistic modelshowed CT-1 as an independent predictor of CRT echo response (p = 0.005; OR 0.97). During follow-up (18 ± 7 months), 21 cardiac events in 18 patients occurred. A Cox multivariable model showed plasma BNP pre-CRT (p = 0.02; CI 1.2–5.6; OR 3.1) and CT1 post-CRT (p = 0.01; CI 1.4–4.3; OR 2.7) as independent predictors of cardiac events. Analysis of CT-1 plasma levels deserves future consideration for larger, longitudinal studies in patients with CHF.  相似文献   
68.

Background

Advanced glycation endproducts (AGEs) and its receptors (RAGEs) are heterogeneous signaling proteins associated to diabetes and responsible of endothelial alterations leading to atherosclerosis progression and graft failure. The aim of this study was to investigate the role of statin in reducing AGEs related endothelial damage.

Methods

Endothelial cell(EC) obtained from leftovers of saphenous vein grafts of non-diabetic patients were incubated with AGEs (2 and 20 μM) and subsequently treated with Simvastatin. Neutrophils (PNM) adherence, ROS production and RAGE and peroxisome proliferator-activated receptors-gamma (PPAR-γ) expression were analyzed. As clinical validation of the in vitro findings, ECs of diabetic patients in optimized glycaemic control administered with a 3 weeks Simvastatin regimen were similarly processed.

Results

Simvastatin blunted the rise in PMN adhesion and ROS generation following stimulation of saphenous vein EC culture with AGEs in vitro. This effect was time dependent and was associated to an increase in PPAR-γ induction paralleled by a decrease in RAGEs expression. Parallely, data from diabetic patients administered with Simvastatin showed a similar significant reduction in PNM adhesion and ROS generation. Simvastatin treatment significantly decreased RAGEs expression in ECs from diabetic patients and determined a slight increase in PPAR-γ expression but the latter failed to reach statistical significance. Interference in the function of these two crucial pathways might be at the root of the statin antinflammatory and antithrombotic effect in the context of AGEs-associated damage.

Conclusions

Despite the recently raised warning on the use of statins in the diabetic population, this study elucidates their cornerstone position in endothelial homeostasis of saphenous grafts in patients with controlled diabetes.  相似文献   
69.
70.
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