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   5485篇
  免费   184篇
  国内免费   40篇
耳鼻咽喉   157篇
儿科学   186篇
妇产科学   291篇
基础医学   315篇
口腔科学   339篇
临床医学   433篇
内科学   1283篇
皮肤病学   70篇
神经病学   376篇
特种医学   232篇
外科学   1221篇
综合类   68篇
预防医学   100篇
眼科学   226篇
药学   165篇
中国医学   3篇
肿瘤学   244篇
  2024年   2篇
  2023年   33篇
  2022年   54篇
  2021年   124篇
  2020年   79篇
  2019年   88篇
  2018年   107篇
  2017年   109篇
  2016年   183篇
  2015年   199篇
  2014年   237篇
  2013年   307篇
  2012年   415篇
  2011年   387篇
  2010年   243篇
  2009年   211篇
  2008年   385篇
  2007年   484篇
  2006年   433篇
  2005年   440篇
  2004年   393篇
  2003年   266篇
  2002年   296篇
  2001年   59篇
  2000年   31篇
  1999年   23篇
  1998年   19篇
  1997年   16篇
  1996年   14篇
  1995年   10篇
  1994年   10篇
  1993年   6篇
  1992年   6篇
  1991年   9篇
  1989年   5篇
  1988年   1篇
  1987年   6篇
  1985年   5篇
  1984年   3篇
  1983年   2篇
  1981年   1篇
  1980年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1963年   1篇
排序方式: 共有5709条查询结果,搜索用时 15 毫秒
91.
92.
93.
ObjectiveThe aim was to compare coronary high-definition CT (HDCT) with standard-definition CT (SDCT) angiography as to radiation dose, image quality and accuracy.ResultsThe intraclass correlation coefficient (ICC) of measured vessel attenuation values in SDCT between the two radiologists was exceedingly good. The ICC was higher in HDCT. The radiation dose of HDCT was higher than that of SDCT. The mean tube current was 180 (mA) in HDCT and 147(mA) in SDCT with the same tube voltage (kVp). There was no significant difference between image quality.ConclusionHDCT has a higher radiation dose but has much more atenuation and the spatial resolution which improve measurement accuracy for imaging coronary arteries.  相似文献   
94.
Naegleria fowleri is a pathogenic free-living amoeba (FLA) that causes an acute fatal disease known as primary amoebic meningoencephalitis (PAM). The major problem for infections with any pathogenic FLA is a lack of effective therapeutics, since PAM has a case mortality rate approaching 99%. Clearly, new drugs that are potent and have rapid onset of action are needed to enhance the treatment regimens for PAM. Diamidines have demonstrated potency against multiple pathogens, including FLA, and are known to cross the blood-brain barrier to cure other protozoan diseases of the central nervous system. Therefore, amidino derivatives serve as an important chemotype for discovery of new drugs. In this study, we validated two new in vitro assays suitable for medium- or high-throughput drug discovery and used these for N. fowleri. We next screened over 150 amidino derivatives of multiple structural classes and identified two hit series with nM potency that are suitable for further lead optimization as new drugs for this neglected disease. These include both mono- and diamidino derivatives, with the most potent compound (DB173) having a 50% inhibitory concentration (IC50) of 177 nM. Similarly, we identified 10 additional analogues with IC50s of <1 μM, with many of these having reasonable selectivity indices. The most potent hits were >500 times more potent than pentamidine. In summary, the mono- and diamidino derivatives offer potential for lead optimization to develop new drugs to treat central nervous system infections with N. fowleri.  相似文献   
95.
Objective: The aim of this study was to evaluate whether exposure to second-hand smoke affected the six-minute walk test (6MWT) of obese non-asthmatic pediatric cases.Methods: Obese pediatric patients (body mass index >95th p) with no existing co-morbidities were included in the study. Smoke exposure was assessed with a self-reported questionnaire completed by the parents. The subjects were divided into two groups: Group 1 consisting of obese children exposed to passive smoking and Group 2 of obese children not exposed to passive smoking. In addition to 6MWT, spirometric flow and volume, including forced expiratory volume in 1 s and peak expiratory flow rate, were also measured in all subjects. The results of the 6MWT were assessed to determine any association with passive smoking.Results: The study included 75 obese pediatric cases (40 male, 35 female) with a mean age of 9.06±0.97 years. The 6MWT results in Group 1 was 501.88±62.12 meters and in Group 2 559.63±72.93 meters. The difference was statistically significant (p=0.001).Conclusions: Passive smoking may negatively affect the respiratory and cardiovascular capacity in obese children, who are already at risk of lower cardiopulmonary function. The evaluation of 6MWT in these pediatric patients may be useful for monitoring and families should be warned about potential problems due to smoking.  相似文献   
96.
Reviews in Endocrine and Metabolic Disorders - Endocrine Disrupting Chemicals (EDCs) are a global problem for environmental and human health. They are defined as “an exogenous chemical, or...  相似文献   
97.
Apelin has been identified as an endogenous ligand of the orphan G-protein-coupled apelin receptor (APJR). These receptors are widely expressed in the central nervous system and periphery and play a role in the regulation of fluid and glucose homeostasis, feeding behavior, vessel formation, cell proliferation and immunity. We aimed to investigate whether water immersion and restraint stress have effects on apelin and APJR expression and apoptosis in heart tissue of male Wistar rats. The cardiac tissues were obtained from control, water immersion and restraint stress (WIRS) and apelin antagonist (F13A) + WIRS groups of rats and embedded in paraffin wax. Immunohistochemical staining methods were used to localize apelin, APJR and TUNEL immunopositive cells. H-SCORE was used for semi-quantitative determinations. Apelin protein levels were determined by Western blot in the cardiac tissues and plasma corticosteroid levels were measured by enzyme immunoassay (EIA). Apelin immunolocalization was found especially in endothelial cells and mast cells and faintly in cardiomyocytes, APJR immunostaining was shown in endothelial cells and cardiomyocytes, and TUNEL reaction was observed in endothelial cells and in some fibroblasts. Apelin expression was significantly increased in the WIRS and F13A + WIRS groups compared to the control group. The APJR reaction was similar in all groups. The number of TUNEL-positive cells was significantly higher in the F13A + WIRS group than that of the control group. Our study showed that WIRS for 6 h increased plasma corticosterone levels and cardiac apelin expression in rats. The increased levels of apelin inhibited stress-induced apoptosis in heart. These results may be important for the therapeutic approach to a variety of stress-related heart disease.  相似文献   
98.
99.
100.
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