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   6980篇
  免费   333篇
  国内免费   76篇
耳鼻咽喉   111篇
儿科学   127篇
妇产科学   258篇
基础医学   559篇
口腔科学   137篇
临床医学   612篇
内科学   1986篇
皮肤病学   89篇
神经病学   372篇
特种医学   292篇
外科学   1391篇
综合类   30篇
预防医学   312篇
眼科学   146篇
药学   312篇
中国医学   3篇
肿瘤学   652篇
  2024年   3篇
  2023年   47篇
  2022年   132篇
  2021年   239篇
  2020年   131篇
  2019年   196篇
  2018年   207篇
  2017年   147篇
  2016年   164篇
  2015年   167篇
  2014年   302篇
  2013年   333篇
  2012年   591篇
  2011年   606篇
  2010年   367篇
  2009年   334篇
  2008年   575篇
  2007年   584篇
  2006年   490篇
  2005年   410篇
  2004年   359篇
  2003年   322篇
  2002年   264篇
  2001年   41篇
  2000年   16篇
  1999年   36篇
  1998年   55篇
  1997年   33篇
  1996年   34篇
  1995年   26篇
  1994年   18篇
  1993年   11篇
  1992年   18篇
  1991年   9篇
  1990年   16篇
  1989年   13篇
  1988年   9篇
  1987年   9篇
  1986年   9篇
  1985年   13篇
  1984年   7篇
  1983年   8篇
  1982年   11篇
  1981年   9篇
  1980年   4篇
  1978年   2篇
  1976年   2篇
  1974年   4篇
  1973年   2篇
  1969年   1篇
排序方式: 共有7389条查询结果,搜索用时 15 毫秒
1.
2.
The aim of the study was to determine the effect of β-glucan on the cytotoxicity and genotoxicity of polypectomized patient's fecal water (FW). Polypectomized volunteers (n = 69) were randomly assigned to consume bread with or without β-glucan, for 3 months. FW was collected at the beginning (t = 0), the 30th and 90th day and 2 wk after the intervention. Cytotoxicity and genotoxicity were estimated on Caco-2 cells, using trypan blue exclusion test and comet assay, respectively. Gastrointestinal symptoms were recorded and subjects kept a 3-day food diary at baseline and after completion. Trypan blue exclusion test revealed cell survival of approximately 87% after incubation with FW. The FW samples showed 49% genotoxicity at the baseline. Genotoxicity in the intervention group decreased during the trial reaching statistical significance on the 90th day compared to control. An increase was noticed 2 wk after the trial, but it still remained significantly lower compared to control. Group-specific analysis for β-glucan also revealed significant decrease in the genotoxicity on the 90th day compared to baseline. β-glucan ingestion in polypectomized patients significantly decreased the genotoxicity of their FW. Our findings suggest that β-glucan consumption could possibly provide protection against colon cancer development.  相似文献   
3.
4.
5.
6.
Among the numerous signaling pathways involved in tumorigenesis, PI3K‐AKT‐mTOR is a key one that regulates diverse cellular functions. However, its prognostic value in esophageal carcinoma remains unclear. In our study, we examined the immunohistochemical expression of phosphorylated (p‐) AKT, mTOR, p70S6K and 4E‐BP1 along with the mutational status of PIK3CA and AKT1 genes by High Resolution Melting Analysis and Pyrosequencing in 44 esophageal carcinomas. The results were correlated with the clinicopathological characteristics of the patients in an effort to define their possible prognostic significance. Total p‐mTOR cytoplasmic expression, assessed in 10 random areas, was positively correlated with tumor stage (Kruskal–Wallis ANOVA, I/II vs III/IV, p = 0.0500). Μoreover, maximum p‐mTOR cytoplasmic immunoexpression, estimated in hot spot areas, was positively associated with tumor grade (Mann–Whitney U test, I/II vs III, p = 0.0565). Interestingly, p‐4E‐BP1 immunoreactivity was negatively correlated with tumor histological grade (Mann–Whitney U test, I/II vs III, p = 0.0427). No mutation was observed in exons 9 and 20 of PIK3CA gene and in exon 4 of AKT1 gene. In conclusion, our findings depict the presence of activated PI3K/AKT/mTOR pathway in esophageal cancer bringing forward p‐mTOR and p‐4E‐BP1 for their potential role in esophageal carcinogenesis. Additional studies are warranted to validate our findings.  相似文献   
7.
Inhaled iloprost controls pulmonary hypertension after cardiopulmonary bypass   总被引:15,自引:0,他引:15  
PURPOSE: Severe pulmonary hypertension (PH) is a major cause of right ventricular (RV) dysfunction. Various iv vasodilator modalities have been used with limited results because of lack of pulmonary selectivity. The aim of the present controlled study was to evaluate the efficacy of inhaled iloprost, a synthetic prostacyclin analogue, in patients with elevated pulmonary vascular resistance (PVR) immediately after separation from cardiopulmonary bypass (CPB). METHODS: Twelve patients with persistent PH after discontinuation of CPB were included in the study. In all patients standard hemodynamic monitoring was used. Inhaled iloprost was administered via nebulized aerosol at a cumulative dose of 0.2 micro g*kg(-1) for a total duration of 20 min. Complete sets of hemodynamic measurements were performed before inhalation (baseline), during and after cessation of the inhalation period. Echocardiographic monitoring of RV function was also used. RESULTS: Inhaled iloprost induced a reduction in the transpulmonary gradient at the end of the inhalation period in comparison to baseline (9.33 +/- 3.83 mmHg vs 17.09 +/- 6.41 mmHg, P < 0.05). The mean pulmonary artery pressure to systemic artery pressure ratio decreased over this period (0.28 +/- 0.08 vs 0.45 +/- 0.17, P < 0.05). A statistically significant decrease of the PVR to systemic vascular resistance ratio was also observed (0.15 +/- 0.05 vs 0.21 +/- 0.05, P < 0.05). Improved indices of RV function were observed in echocardiographic monitoring. CONCLUSION: Inhaled iloprost appears to be a selective pulmonary vasodilator and may be effective in the initial treatment of PH and the improvement of RV performance in the perioperative setting.  相似文献   
8.
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