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   209517篇
  免费   3013篇
  国内免费   201篇
耳鼻咽喉   1527篇
儿科学   7666篇
妇产科学   3915篇
基础医学   19870篇
口腔科学   2716篇
临床医学   15375篇
内科学   38173篇
皮肤病学   1318篇
神经病学   18422篇
特种医学   10094篇
外国民族医学   4篇
外科学   35065篇
综合类   3133篇
现状与发展   3篇
一般理论   27篇
预防医学   20360篇
眼科学   4033篇
药学   12130篇
  1篇
中国医学   889篇
肿瘤学   18010篇
  2023年   413篇
  2022年   1044篇
  2021年   1643篇
  2020年   985篇
  2019年   1266篇
  2018年   23205篇
  2017年   18283篇
  2016年   20498篇
  2015年   2183篇
  2014年   2438篇
  2013年   2755篇
  2012年   9885篇
  2011年   23710篇
  2010年   20292篇
  2009年   12801篇
  2008年   21441篇
  2007年   23657篇
  2006年   2467篇
  2005年   3855篇
  2004年   4891篇
  2003年   5591篇
  2002年   3579篇
  2001年   614篇
  2000年   700篇
  1999年   429篇
  1998年   387篇
  1997年   326篇
  1996年   224篇
  1995年   202篇
  1994年   187篇
  1993年   132篇
  1992年   181篇
  1991年   241篇
  1990年   248篇
  1989年   195篇
  1988年   154篇
  1987年   134篇
  1986年   109篇
  1985年   144篇
  1984年   95篇
  1983年   72篇
  1982年   77篇
  1981年   55篇
  1980年   80篇
  1979年   52篇
  1978年   48篇
  1974年   55篇
  1938年   63篇
  1932年   57篇
  1930年   48篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
32.
Gastroesophageal reflux is the most common benign disorder of the esophagus and laparoscopic Nissen fundoplication has become the standard surgical treatment for its treatment. In our area, where the use of bougie calibration is debatable, postoperative dysphagia is encountered often after this surgery although it is usually not permanent. The aim of this study was to investigate the effect of using a soft silicone tube 39 F in diameter for esophageal calibration during laparoscopic Nissen fundoplication on the incidence of postoperative dysphagia. We divided cases scheduled to undergo laparoscopic Nissen fundoplication between January 2009 and November 2010 into two groups, each consisting 25 patients. Esophageal calibration with a 39 F silicone orogastric tube was used for the first group while there was no operative calibration in the second group. The surgical duration was recorded; the presence and severity of the postoperative dysphagia was calculated by using a dysphagia severity scoring system during the 1-year postoperative follow-up. The dysphagia severity scores were significantly lower in group 1 than group 2 on the postoperative second day and at the end of the first week and first month. We did not find a significant difference at the end of the 6-month and first year. There was also no significant difference regarding surgery duration. The use of a soft orogastric tube 39 F in diameter for esophagus calibration during laparoscopic Nissen fundoplication has significantly decreased the incidence of postoperative transient dysphagia without affecting the duration of surgery. Although dysphagia gradually resolves in the majority of patients, a safe and easy calibration method for its prevention is worth developing, and we believe that the use of our method in larger series could be beneficial.  相似文献   
33.
34.
35.
Hepatitis C is a global public health problem, and Pakistan is the second largest country in the globe with highest prevalence rate of hepatitis C virus (HCV). Until 2014, pegylated interferon (PEG-IFN) plus ribavirin (RBV) has been the standard therapy for HCV, however, owing to its adverse side effects and very low sustained virologic response (SVR) rates therapeutics trend is shifted toward direct-acting antivirals. Tripartite motif containing 22 (TRIM22) is a dynamic antiviral protein that can inhibit multiple viruses in vivo. Expression of TRIM22 mRNA has been linked to outcome of PEG-IFN and ribavirin therapy, where its higher expression leads to rapid virus clearance. However, in terms of therapy with direct-acting antiviral (DAA) or double DAA, impact of TRIM22 expression is largely unknown. These new drugs show more than 90% of SVR rates and lesser side effects and have proven to be better than IFN therapy. Endogenous IFN system suppresses various pathogens through the induction of antiviral effectors termed as interferon-stimulating genes (ISGs). We have studied the expression levels of one of these antiviral effectors, TRIM22 in response to sofosbuvir (SOF) and daclatasvir (DAC) in combination with RBV, using quantitative PCR in the peripheral blood mononuclear cells (PBMCs) of HCV-infected patients. We have observed sustained virus clearance in more than 90% of patients treated with DAA and double DAA and have seen the expression of TRIM22 to be higher in patients who attained SVR as compared to the untreated patients. We have also observed downregulation of TRIM22 in patients who failed to attain rapid virus clearance, and upregulation in those who achieved rapid clearance of virus. Genetic factors that determine the lower TRIM22 expression in these patients are needed to be explored that may also play a role in lower response to anti-HCV therapy. Endogenous IFN system and effects of antiviral proteins in response to DAA therapy is needed to be studied in order to better understand the host response toward these drugs to make them more effective.  相似文献   
36.
37.
SPECT with 99mTc-labeled agents is better able to detect viability after nitrate administration. Nitrates induce vasodilation and may increase blood flow to severely hypoperfused but viable myocardium, thereby enhancing tracer delivery and improving the detection of viability. Quantitative data on the changes in blood flow are lacking in SPECT but can be provided by PET. The aim of the present study was to use PET to evaluate whether nitrate administration increases blood flow to chronically dysfunctional but viable myocardium. METHODS: 13N-Ammonia PET was used to quantitatively assess blood flow, and 18F-FDG PET was used as the gold standard to detect viable myocardium. Twenty-five patients with chronic ischemic left ventricular dysfunction underwent 13N-ammonia PET at rest and after nitrate administration. RESULTS: A significant increase in nitrate-enhanced blood flow was observed in viable segments (from 0.55 +/- 0.15 to 0.68 +/- 0.24 mL/min/g, P < 0.05). No statistically significant change in blood flow was observed in nonviable segments (0.60 +/- 0.20 vs. 0.55 +/- 0.18 mL/min/g). A ratio of at least 1.1 for nitrate-enhanced flow to resting flow allowed optimal detection of viable myocardium, yielding a sensitivity of 82% with a specificity of 100%. CONCLUSION: 13N-Ammonia PET showed a significant increase in nitrate-enhanced blood flow in viable myocardium, whereas blood flow remained unchanged after nitrate administration in nonviable myocardium. Nitrate use during myocardial perfusion imaging will lead to improved assessment of myocardial viability.  相似文献   
38.
39.
40.
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