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   24190篇
  免费   1617篇
  国内免费   158篇
耳鼻咽喉   259篇
儿科学   565篇
妇产科学   442篇
基础医学   2822篇
口腔科学   967篇
临床医学   2135篇
内科学   5180篇
皮肤病学   520篇
神经病学   1518篇
特种医学   705篇
外国民族医学   5篇
外科学   3418篇
综合类   575篇
一般理论   17篇
预防医学   1941篇
眼科学   966篇
药学   2249篇
中国医学   249篇
肿瘤学   1432篇
  2024年   24篇
  2023年   282篇
  2022年   322篇
  2021年   1324篇
  2020年   882篇
  2019年   1102篇
  2018年   1318篇
  2017年   920篇
  2016年   995篇
  2015年   1012篇
  2014年   1387篇
  2013年   1611篇
  2012年   2211篇
  2011年   2252篇
  2010年   1307篇
  2009年   1001篇
  2008年   1485篇
  2007年   1360篇
  2006年   1142篇
  2005年   960篇
  2004年   753篇
  2003年   649篇
  2002年   564篇
  2001年   94篇
  2000年   101篇
  1999年   102篇
  1998年   76篇
  1997年   61篇
  1996年   64篇
  1995年   51篇
  1994年   31篇
  1993年   47篇
  1992年   34篇
  1991年   29篇
  1990年   30篇
  1989年   38篇
  1988年   36篇
  1987年   18篇
  1986年   18篇
  1985年   20篇
  1984年   31篇
  1983年   19篇
  1982年   26篇
  1981年   18篇
  1980年   15篇
  1979年   22篇
  1978年   18篇
  1976年   19篇
  1975年   13篇
  1974年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
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   
5.
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   
6.
Nonalcoholic fatty liver disease (NAFLD) is a major cause of liver‐related morbidity; its prevalence is elevating due to the rising epidemic of obesity. Several clinical trials have examined the effects of curcumin supplementation on anthropometric variables in NAFLD patients with inconclusive results. This dose–response meta‐analysis aimed to evaluate the impact of curcumin supplementation on body mass index (BMI), body weight, and waist circumference (WC) in patients with NAFLD. A systematic review of the literature was conducted using PubMed/Medline, ISI Web of Science, Scopus, Cochrane Library, EMBASE, Google Scholar, Sid.ir, and Magiran.com to identify eligible studies up to March 2019. A meta‐analysis of eligible studies was performed using the random‐effects model to estimate the pooled effect size. Eight randomized controlled trials with 520 participants (curcumin group = 265 and placebo group = 255) were included. Supplementation dose and duration ranged from 70 to 3,000 mg/day and 8 to 12 weeks, respectively. Curcumin supplementation significantly reduced BMI (weighted mean difference [WMD] = ?0.34 kg/m2, 95% CI [?0.64, ?0.04], p < .05) and WC (WMD = ?2.12 cm, 95% CI [?3.26, ?0.98], p < .001). However, no significant effects of curcumin supplementation on body weight were found. These results suggest that curcumin supplementation might have a positive effect on visceral fat and abdominal obesity that have been associated with NAFLD.  相似文献   
7.
8.
9.
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital condition. It responds well to early diagnosis and treatment, but otherwise the prognosis is poor. We present our case series of 12 patients (mean age, 2 ± 2.58 yr; age range, 2 mo–8 yr), emphasizing the diagnostic process and discussing our surgical results. The diagnosis of ALCAPA should be suspected in infants who have dilated cardiomyopathy with electrocardiographic changes that suggest ischemia, and in older children who have isolated mitral regurgitation. When clinical suspicion is high, the results of 2-dimensional echocardiography combined with color-flow Doppler studies in expert hands can establish the diagnosis, thus avoiding angiography in critically ill infants. The treatment of choice in our patients was transfer and reimplantation of the left coronary artery onto the ascending aorta. There were 2 deaths: both were infants in extremis who underwent emergency surgery. An older child with severe ventricular dysfunction was given mechanical ventricular assistance and then heart transplantation. As of this report, all 10 survivors remained well and asymptomatic.  相似文献   
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