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   3912篇
  免费   283篇
  国内免费   106篇
耳鼻咽喉   11篇
儿科学   93篇
妇产科学   12篇
基础医学   140篇
口腔科学   17篇
临床医学   746篇
内科学   712篇
皮肤病学   6篇
神经病学   136篇
特种医学   32篇
外科学   94篇
综合类   446篇
预防医学   1313篇
眼科学   16篇
药学   412篇
  2篇
中国医学   65篇
肿瘤学   48篇
  2024年   3篇
  2023年   46篇
  2022年   29篇
  2021年   112篇
  2020年   83篇
  2019年   83篇
  2018年   92篇
  2017年   93篇
  2016年   99篇
  2015年   99篇
  2014年   191篇
  2013年   290篇
  2012年   211篇
  2011年   215篇
  2010年   169篇
  2009年   176篇
  2008年   187篇
  2007年   198篇
  2006年   193篇
  2005年   167篇
  2004年   139篇
  2003年   121篇
  2002年   120篇
  2001年   107篇
  2000年   89篇
  1999年   87篇
  1998年   89篇
  1997年   86篇
  1996年   72篇
  1995年   119篇
  1994年   72篇
  1993年   53篇
  1992年   54篇
  1991年   29篇
  1990年   39篇
  1989年   35篇
  1988年   31篇
  1987年   13篇
  1986年   28篇
  1985年   21篇
  1984年   26篇
  1983年   22篇
  1982年   29篇
  1981年   19篇
  1980年   19篇
  1979年   12篇
  1978年   11篇
  1977年   8篇
  1976年   9篇
  1974年   3篇
排序方式: 共有4301条查询结果,搜索用时 202 毫秒
81.
BackgroundThe exposure of children to lead has decreased in recent years, thanks notably to the banning of leaded gasoline. However, lead exposure remains a matter of public health concern, because no toxicity threshold has been observed, cognitive effects having been demonstrated even at low levels. It is therefore important to update exposure assessments. A national study was conducted, in 2008–2009, to determine the blood lead level (BLL) distribution in children between the ages of six months and six years in France. We also assessed the contribution of environmental factors.MethodsThis cross-sectional survey included 3831 children recruited at hospitals. Two-stage probability sampling was carried out, with stratification by hospital and French region. Sociodemographic characteristics were recorded, and blood samples and environmental data were collected by questionnaire. Generalized linear model and quantile regression were used to quantify the association between BLL and environmental risk factors.ResultsThe geometric mean BLL was 14.9 μg/l (95% confidence interval (CI) = [14.5–15.4]) and 0.09% of the children (95% CI = [0.03–0.15]) had BLLs exceeding 100 μg/l, 1.5% (95% CI = [0.9–2.1] exceeding 50 μg/l. Only slight differences were observed between French regions. Environmental factors significantly associated with BLL were the consumption of tap water in homes with lead service connections, peeling paint or recent renovations in old housing, hand-mouth behavior, passive smoking and having a mother born in a country where lead is often used.ConclusionsIn children between the ages of one and six years in France, lead exposure has decreased over the last 15 years as in the US and other European countries. Nevertheless still 76,000 children have BLL over 50 μg/l and prevention policies must be pursued, especially keeping in mind there is no known toxicity threshold.  相似文献   
82.
Critical reassessment of established inotropic drugs such as the phosphodiesterase inhibitors and the digitalis glycosides has reaffirmed the need for novel cardiotonic agents that will not only beneficially affect the haemodynamic and functional impairment of patients with overt congestive heart failure, but also prevent its clinical manifestation and reduce the high mortality. None of the drugs examined in these directions - calcium sensitisers, β-receptor blockers, sodium channel modulators, digitalis derivatives - have been shown to achieve these goals. The research on endogenous digitalis did not, as was hoped, reveal a general strategy for improving the therapeutic index of cardiac glycosides. The proof that Na+/K+-transporting ATPase of cardiac muscle is the molecular point of attack (receptor) for the inotropic and toxic effects of digitalis-like acting C/D-cis and C/D-trans steroids revealed the cyclopentano-perhydrophenanthrene nucleus as their common pharmacophoric lead structure. This has opened a wide field for lead development in the direction of derivatives that favourably discriminate between the inotropy-linked α1-isoform and the toxicity-linked α3-isoform of Na+/K+-ATPase as the basis for the design of inotropic agents with high therapeutic margin.  相似文献   
83.
84.
Cardiac implantable electronic devices (CIEDs) frequently need to be extracted due to infection, hardware failure, and other causes. The extraction of the CIED is typically performed using percutaneous methods. While these procedures are mostly performed without incident there is a small risk of significant complications. Dedicated imaging pre‐CEID removal to include the central veins and heart with multidetector computed tomography (MDCT) can be utilized to evaluate the lead course and termination, the integrity of the central veins and cardiac chambers, and identify potential complications that may alter the lead extraction procedure as well as reimplantation of subsequent leads. Indications for preprocedural imaging, the technique of dedicated preprocedural lead extraction MDCT, and the approach to the interpretation of the images is discussed in this review.  相似文献   
85.
Breast cancer is the second most common cancer worldwide, accounting for 25% of all female cancers. Although the survival rate has increased significantly in the past few decades, patients who develop secondary site metastasis as well as those diagnosed with triple negative breast cancer still represent a real unmet medical challenge. Previous studies have shown that chloropyramine ( C4 ) inhibits FAK‐VEGFR3 signalling. More recently, C4 is reported to have SASH1 inducing properties. However, C4 exerts its antitumour and antiangiogenic effects at high micromolar concentrations (>100 μm ) that would not be compatible with further drug development against invasive breast cancer driven by FAK signalling. In this study, molecular modelling guided structural modifications have been introduced to the chloropyramine C4 scaffold to improve its activity in breast cancer cell lines. Seventeen compounds were designed and synthesized, and their antiproliferative activity was evaluated against three human breast cancer lines (MDA‐MB‐231, BT474 and T47D). Compound 5c was identified to display an average activity of IC50 = 23.5–31.3 μm , which represents a significant improvement of C4 activity in the same assay model. Molecular modelling and pharmacokinetic studies provided more promising insights into the mechanistic features of this new series.  相似文献   
86.
87.
《Heart rhythm》2021,18(9):1566-1576
  1. Download : Download high-res image (186KB)
  2. Download : Download full-size image
  相似文献   
88.
89.
90.
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