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   18279篇
  免费   767篇
  国内免费   245篇
耳鼻咽喉   86篇
儿科学   447篇
妇产科学   763篇
基础医学   772篇
口腔科学   123篇
临床医学   6331篇
内科学   2944篇
皮肤病学   166篇
神经病学   866篇
特种医学   1100篇
外科学   1176篇
综合类   2658篇
现状与发展   1篇
预防医学   497篇
眼科学   210篇
药学   770篇
  6篇
中国医学   190篇
肿瘤学   185篇
  2024年   7篇
  2023年   78篇
  2022年   164篇
  2021年   239篇
  2020年   310篇
  2019年   280篇
  2018年   342篇
  2017年   336篇
  2016年   372篇
  2015年   370篇
  2014年   871篇
  2013年   989篇
  2012年   914篇
  2011年   1027篇
  2010年   934篇
  2009年   945篇
  2008年   994篇
  2007年   1075篇
  2006年   1081篇
  2005年   1024篇
  2004年   904篇
  2003年   707篇
  2002年   640篇
  2001年   658篇
  2000年   537篇
  1999年   483篇
  1998年   399篇
  1997年   403篇
  1996年   346篇
  1995年   329篇
  1994年   268篇
  1993年   227篇
  1992年   197篇
  1991年   174篇
  1990年   130篇
  1989年   77篇
  1988年   83篇
  1987年   62篇
  1986年   58篇
  1985年   76篇
  1984年   43篇
  1983年   32篇
  1982年   41篇
  1981年   20篇
  1980年   10篇
  1979年   7篇
  1978年   10篇
  1977年   5篇
  1976年   8篇
  1974年   3篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
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   
3.
4.
We present a patient with both dynamic left ventricular outflow tract obstruction and valvular aortic stenosis. The aortic valve was calcified, and velocities and gradients measured by continuous‐wave Doppler met standard criteria for severe aortic stenosis. The increased subvalvular velocities invalidated assumptions of the simplified Bernoulli equation; correction using the longer form of the Bernoulli equation suggested a lower but still significant gradient. The complex shape of the subvalvular spectral Doppler envelope indicated supranormal systolic function and dynamic left ventricular outflow obstruction. Left heart catheterization with an end‐hole catheter was required to determine the subvalvular and valvular components of the obstruction.  相似文献   
5.
金丽梅 《中外医疗》2016,(25):185-186
目的:探讨彩色多普勒超声诊断卵巢肿瘤蒂扭转的临床意义。方法方便选取2012―2015年该院收治的58例疑似卵巢肿瘤蒂扭转患者作为观察目标,入选病例均应用彩色多普勒超声进行检查,并将检查结果同术后病理检查结果进行比较。结果58例患者中,术后病理证实卵巢肿瘤蒂扭转者51例,彩色多普勒超声共确诊49例,检查准确率为96.1%;囊壁增厚、腹腔或盆腔积液、可见混合型团块是卵巢肿瘤蒂扭转的主要彩超表现。结论卵巢肿瘤蒂扭转应用彩色多普勒超声诊断,可显著提高诊断准确率,具有积极的临床使用和推广价值。  相似文献   
6.
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   
7.
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