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   19881篇
  免费   1239篇
  国内免费   146篇
耳鼻咽喉   165篇
儿科学   447篇
妇产科学   383篇
基础医学   2231篇
口腔科学   764篇
临床医学   1849篇
内科学   4249篇
皮肤病学   428篇
神经病学   1271篇
特种医学   485篇
外国民族医学   7篇
外科学   2674篇
综合类   523篇
一般理论   15篇
预防医学   1738篇
眼科学   777篇
药学   1897篇
中国医学   227篇
肿瘤学   1136篇
  2024年   20篇
  2023年   227篇
  2022年   552篇
  2021年   1131篇
  2020年   749篇
  2019年   910篇
  2018年   1082篇
  2017年   751篇
  2016年   827篇
  2015年   817篇
  2014年   1110篇
  2013年   1285篇
  2012年   1742篇
  2011年   1805篇
  2010年   1059篇
  2009年   802篇
  2008年   1168篇
  2007年   1068篇
  2006年   902篇
  2005年   786篇
  2004年   612篇
  2003年   499篇
  2002年   434篇
  2001年   76篇
  2000年   76篇
  1999年   75篇
  1998年   56篇
  1997年   52篇
  1996年   46篇
  1995年   42篇
  1994年   21篇
  1993年   37篇
  1992年   42篇
  1991年   28篇
  1990年   29篇
  1989年   33篇
  1988年   27篇
  1987年   26篇
  1986年   29篇
  1985年   26篇
  1984年   23篇
  1983年   18篇
  1982年   17篇
  1981年   12篇
  1980年   13篇
  1979年   14篇
  1976年   12篇
  1974年   11篇
  1972年   13篇
  1969年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Objective: To determine whether packed red blood cell (PRBC) transfusion affects post-prandial superior mesenteric artery blood flow velocities (SMA BFVs) in very-low birth weight (VLBW) neonates and if so, at what time point after transfusion restoration of previous SMA BFV patterns occurs.

Design/Methods: VLBW pre-term neonates, older than 14 days and tolerating bolus enteral feedings administered every 3?h were enrolled in this prospective observational study. Pulsed Doppler ultrasound was used to measure pre- and post-prandial (at 45?min) time-averaged mean, peak and end diastolic velocities (TAMV, PSV, EDV) immediately before and after 15?ml/kg of PRBC transfusion was given over 3?h; patent ductus arteriosus (PDA) status was also evaluated. Subsequent pre- and post-prandial SMA BFVs were recorded 24 and 48?h after the transfusion.

Results: Pre- and post-prandial measurements were obtained for 21 out of 25 enrolled infants. Post-prandial SMA BFVs were attenuated during the feedings immediately after transfusion; at 24 and 48?h after transfusion, changes in post-prandial SMA BFVs were similar to those measured prior to transfusion; the presence of the PDA did not affect results.

Conclusions: PRBC transfusion blunted SMA BFV responses to feedings immediately after the transfusion with normalization observed 24?h post-transfusion.  相似文献   
4.
ABSTRACT

Purpose

To investigate the expression of IL-11 and its receptor IL-11Rα and to quantify density of CD163+ M2 macrophages in proliferative diabetic retinopathy (PDR).  相似文献   
5.
6.
7.
8.
9.
Purpose: Traffic accidents are one of the major health problems in the world, being the first cause of burden of illness and the second leading cause of death in Iran. The Sistan-Baluchestan province is one of the most accidental provinces of Iran with the highest rate of accidents-caused deaths. This study was conducted to determine the risk factors associated with traffic accidents in Zahedan through 2013 to 2016. Methods: This analytical cross-sectional study was carried out on 223 drivers from Zahedan who were traumatized by traffic accident and sent to Zahedan hospitals. The data were obtained through interviews taken by the trained interviewers via refereeing to the medical records and collected in the researcher-made checklist. Census was obtained from the study subjects. For data analysis, independent t-test, one-way ANOVA, Chi-square and logistic regression were used with the Stata software version 11.0. Results: In this study, 223 male subjects with the mean age of (32.54 ± 12.95) years, 39.8% single and 60.2% married, entered for investigation. Most accidents (38.8%) occurred between 12:00 to 17:59. While driving, 47.1% of the study subjects were using cell phones, 89.1% had manual use of mobile phones, 21.9% had a habit of sending short message service (SMS) and 23.4% had sent SMS within 10 min before the accident. The one way analysis of variance showed that the mean age of individuals with marital status, driving experience, education and accident with motorcycle were significantly different (p < 0.05). Also, the multivariate logistic regression test indicated a significant relationship of smoking, ethnicity, insurance and SMS typing while driving with motorcycle accident (p < 0.05). Conclusion: In this study, SMS and smoking while driving had the highest risk among the variables studied in the motorcycle accidents. Therefore, effective education attempting to enhance people''s awareness about the consequences of using cell phone and smoking during driving to reduce traffic accidents seems necessary.  相似文献   
10.

Background and study aims

Acute upper gastrointestinal bleeding is one of the main causes of hospitalisation. The purpose of this study was to determine the prognostic factors in non-variceal upper gastrointestinal bleeding.

Patients and methods

Clinical outcomes, demographic and laboratory variables of the subjects were collected from the HIS software and national code with the SQL format from three hospitals in Qazvin. The data were linked to the database software designed by the author. Clinical and upper endoscopic findings of patients’ records were collected through a questionnaire form in the designed software database.

Results

In this study, 29.2% of patients with favourable outcome and 64.2% of patients with unfavourable clinical outcomes had a history of anticoagulant drug use before hospitalisation (p?<?0.001). The prevalence of chronic cardiovascular disease, chronic liver disease, chronic lung disease, diabetes and dialysis was higher in subjects with poor clinical outcomes than those with a favourable clinical outcome.53.1% of subjects with favourable clinical outcome and 90.5% of subjects with undesirable clinical outcomes received packed red blood cell transfusion (p?<?0.001). 16.1% of subjects with desirable clinical outcome and 86.3% of subjects with undesirable clinical outcomes received endoscopic haemostatic treatment which was statistically significant (p?<?0.001).

Conclusion

Undesirable clinical outcome in patients with acute non-variceal upper gastrointestinal bleeding has a significant statistical association with longer hospitalisation, chronic underlying disease, anticoagulant administration, packed red blood cell infusion, higher Forrest stage, low systolic blood pressure, higher age, low haemoglobin, low platelet count, high INR and high BUN at the onset of diagnosis.  相似文献   
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