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   1519篇
  免费   101篇
  国内免费   25篇
儿科学   158篇
妇产科学   14篇
基础医学   139篇
口腔科学   66篇
临床医学   148篇
内科学   346篇
皮肤病学   38篇
神经病学   31篇
特种医学   328篇
外科学   89篇
综合类   24篇
预防医学   68篇
眼科学   16篇
药学   88篇
  1篇
中国医学   1篇
肿瘤学   90篇
  2023年   4篇
  2022年   7篇
  2021年   13篇
  2020年   8篇
  2019年   13篇
  2018年   25篇
  2017年   19篇
  2016年   22篇
  2015年   31篇
  2014年   26篇
  2013年   49篇
  2012年   12篇
  2011年   14篇
  2010年   40篇
  2009年   80篇
  2008年   22篇
  2007年   42篇
  2006年   41篇
  2005年   35篇
  2004年   25篇
  2003年   25篇
  2002年   25篇
  2001年   23篇
  2000年   23篇
  1999年   31篇
  1998年   101篇
  1997年   119篇
  1996年   114篇
  1995年   77篇
  1994年   82篇
  1993年   98篇
  1992年   18篇
  1991年   18篇
  1990年   19篇
  1989年   45篇
  1988年   40篇
  1987年   26篇
  1986年   33篇
  1985年   31篇
  1984年   17篇
  1983年   15篇
  1982年   19篇
  1981年   34篇
  1980年   20篇
  1979年   8篇
  1978年   8篇
  1977年   21篇
  1976年   19篇
  1975年   6篇
  1970年   1篇
排序方式: 共有1645条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
Homer  MJ 《Radiology》1985,157(1):259-260
A new needle-wire system has been developed for localization of nonpalpable breast lesions. The curved-end wire, which is made of a tough pseudoelastic alloy, eliminates many of the pitfalls of this procedure for both the radiologist and the surgeon. Advantages of this new system include the ability to anchor the needle during filming, the ability to easily reposition the needle if necessary, the option of injecting dye, the inability to transect the wire during surgery, and the option of leaving both the needle and wire in place in the subject to allow easier dissection during biopsy.  相似文献   
85.
86.
Background Stress echocardiography is useful for assessing patients with coronary artery disease unable to undergo formal exercise testing. Considerable skill is required to avoid large intra- and inter-observer variability due to poor endocardial definition. Intravenous ultrasound contrast agents are now available which may improve this variability. Aim To study intravenous Sonovue in assessing wall motion score and ejection fraction (EF) during stress echocardiography. Methods Thirty-eight patients undergoing arbutamine stress echocardiography for known or suspected coronary artery disease were studied. Echocardiographic analysis of wall motion score index, endocardial border detection (EBD) and EF was performed at rest and at peak stress before and after intravenous injection of Sonovue, by experienced and inexperienced observers. Results All three observers noted an improvement in endocardial border definition following Sonovue (p=<0.001). At baseline, there was a significant difference in wall motion score index between experienced and inexperienced observers at rest (p=0.01) and at peak stress (p=0.001). Following Sonovue administration this was no longer significant (p=0.07, p=0.114). Intra-observer variability of end diastolic, end systolic volumes (ESV) and EF improved following contrast (p<0.05) at rest and during stress. Conclusion Sonovue significantly improved EBD and reduced intra-observer variability of EF at rest and during peak arbutamine infusion.  相似文献   
87.

OBJECTIVE:

Inflammation plays an important role in the development of chronic lung disease (CLD), which has become a major cause of morbidity in surviving infants less than 1250 g at birth. The authors hypothesized that the progression of this inflammation and, therefore, the establishment of CLD would be decreased with the use of early prophylactic inhaled corticosteroids. Short, and long term respiratory and neurodevelopmental outcomes were also examined.

DESIGN:

A double-blind, randomized placebo controlled trial.

SETTING:

Level-III neonatal intensive care unit.

POPULATION STUDIED:

Sixty infants less than 1250 g at birth, diagnosed with respiratory distress syndrome and requiring ventilatory support at 72 h of age were enrolled in the study.

INTERVENTION:

Infants enrolled received either placebo or beclomethasone diproprionate by a metered dose inhaler, which was used in-line with the ventilator circuit while the infant was ventilated and then via a spacer until 28 days of age.

RESULTS:

Thirty infants were given beclomethasone and 30 were given placebo. There were two deaths in each group. Among the surviving infants, the frequency of moderate-to-severe CLD was 17% in each study group. Mean time to extubation was not different for beclomethasone compared with placebo at 16.4 and 12.5 days (P=0.12), respectively. The requirement for intravenous corticosteroids was lower in the beclomethasone-treated group (RR 0.67, 95% CI 0.43 to 1.04), although this difference was not statistically significant. The incidence of growth failure, infection and intraventricular hemmorhage did not differ between the two groups. Long term outcomes were not different with respect to the incidence of respiratory re-admissions, cerebral palsy, developmental delay, blindness or deafness.

CONCLUSIONS:

Early treatment with inhaled beclomethasone diproprionate did not reduce the incidence of CLD or decrease the duration of mechanical ventilation. The decrease in intravenous corticosteroid use was not statistically significant. Long term outcome was not affected.  相似文献   
88.
The breast is a complex anatomical structure where achieving a homogeneous dose distribution with radiation treatment is difficult. Despite obvious similarities in the approach to such treatment (using tangents) there is variation in the process of simulation, planning and treatment between radiation oncologists. Previous Australasian studies in the treatment of lung cancer, prostate cancer and Hodgkin’s disease highlighted considerable variation in many areas of treatment. As part of a multicentre breast phantom study involving 10 radiation oncology departments throughout New South Wales (NSW) and the Australian Capital Territory (ACT), a 22-question survey was distributed. The aim of the survey was to assess the extent of variation in the approach to the simulation, planning and treatment of early breast cancer using tangents. Responses from 10 different radiation oncology departments revealed variation in most areas of the survey. There is no reason to assume similar variations do not occur Australasia wide. Studies involving overseas radiation oncologists also reveal a wide variation in treating early breast cancer. The consequences of such variations remain unclear.  相似文献   
89.
A patient with progressive osteolysis of the carpal and tarsal bones with glomerulonephritis of unusual severity is described. There was a notable absence of osteodystrophy in this and other reported cases who had chronic renal failure.  相似文献   
90.
Pneumocystis carinii pneumonia studied by gallium-67 scanning   总被引:1,自引:0,他引:1  
The validity and reliability of gallium-67 (Ga-67) scanning for diagnosis and follow-up of Pneumocystis carinii pneumonia (PCP) were assessed in 34 patients thought to have pulmonary complications of acquired immunodeficiency syndrome (AIDS). Overall sensitivity was 94% and specificity 74%. Among patients with normal or equivocal chest radiographs at the time of admission, sensitivity was 86% and specificity 85%. The authors consider Ga-67 scanning a valid and reliable adjunct in the diagnosis of PCP in AIDS patients with respiratory symptoms when the chest radiograph is normal or equivocal.  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