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   986篇
  免费   37篇
  国内免费   3篇
耳鼻咽喉   3篇
儿科学   72篇
妇产科学   14篇
基础医学   108篇
口腔科学   26篇
临床医学   102篇
内科学   229篇
皮肤病学   21篇
神经病学   29篇
特种医学   254篇
外科学   50篇
综合类   10篇
预防医学   33篇
眼科学   5篇
药学   29篇
中国医学   1篇
肿瘤学   40篇
  2022年   3篇
  2021年   4篇
  2018年   14篇
  2017年   12篇
  2016年   8篇
  2015年   12篇
  2014年   17篇
  2013年   17篇
  2012年   23篇
  2011年   10篇
  2010年   33篇
  2009年   40篇
  2008年   26篇
  2007年   18篇
  2006年   20篇
  2005年   17篇
  2004年   17篇
  2003年   15篇
  2002年   10篇
  2001年   10篇
  2000年   7篇
  1999年   14篇
  1998年   50篇
  1997年   67篇
  1996年   50篇
  1995年   40篇
  1994年   51篇
  1993年   52篇
  1992年   9篇
  1991年   11篇
  1990年   10篇
  1989年   36篇
  1988年   40篇
  1987年   30篇
  1986年   29篇
  1985年   27篇
  1984年   12篇
  1983年   22篇
  1982年   17篇
  1981年   18篇
  1980年   21篇
  1979年   4篇
  1978年   8篇
  1977年   12篇
  1976年   9篇
  1975年   18篇
  1973年   4篇
  1952年   3篇
  1948年   5篇
  1935年   2篇
排序方式: 共有1026条查询结果,搜索用时 0 毫秒
81.
Objectives: To assess the influence of clinical status on the association between total plasma bilirubin and unbound bilirubin on death or adverse neurodevelopmental outcomes at 18–22 months corrected age in extremely low birth weight infants. Method: Total plasma bilirubin and unbound bilirubin were measured in 1101 extremely low birth weight infants at 5 ± 1 days of age. Clinical criteria were used to classify infants as clinically stable or unstable. Survivors were examined at 18–22 months corrected age by certified examiners. Outcome variables were death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss, and death prior to follow‐up. For all outcomes, the interaction between bilirubin variables and clinical status was assessed in logistic regression analyses adjusted for multiple risk factors. Results: Regardless of clinical status, an increasing level of unbound bilirubin was associated with higher rates of death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss and death before follow‐up. Total plasma bilirubin values were directly associated with death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss, and death before follow‐up in unstable infants, but not in stable infants. An inverse association between total plasma bilirubin and death or cerebral palsy was found in stable infants. Conclusions: In extremely low birth weight infants, clinical status at 5 days of age affects the association between total plasma bilirubin and death or adverse neurodevelopmental outcomes at 18–22 months of corrected age. An increasing level of UB is associated a higher risk of death or adverse neurodevelopmental outcomes regardless of clinical status. Increasing levels of total plasma bilirubin are directly associated with increasing risk of death or adverse neurodevelopmental outcomes in unstable, but not in stable infants.  相似文献   
82.
新缩瞳剂包公藤甲素人工合成研究   总被引:11,自引:0,他引:11  
包公藤甲素是从包公藤(Erycibe obtusifolia Benth.)茎中提得的一个新莨菪烷生物碱,具有强烈的缩瞳作用,临床用于治疗青光眼。本文报道用合成的6β-乙酰氧基托品酮为原料,经卤代、水解、还原和N-去甲基化等反应合成包甲素(8)。经光谱测定证实8与天然包甲素的结构完全一致。合成品系外消旋体,其作用机理与天然品相同,而强度则减半。  相似文献   
83.
84.
Huntington disease (HD) is caused by an expanded CAG repeat sequence in the HD gene. Although the age at onset is correlated to the CAG repeat length, this correlation only explains approximately half of the variation in onset age. Less variation between siblings indicates that the variation is, in part, explained by genetic modifiers. We analyzed polymorphic loci within or close to the HD gene on the HD chromosome in Danish HD patients. We found one specific haplotype segregating with later age at onset, compared with patients with similar CAG repeat length and another haplotype. The nine Danish families in the study carrying this haplotype most likely have a common founder. Several of the polymorphic loci displayed alleles that may be specific to the late-onset haplotype, implicating that from this study we cannot determine which of the loci tested (or other polymorphic loci in this chromosomal area) do in fact contain genetic modifiers of age at onset.  相似文献   
85.
86.
Medullary carcinoma of the breast: mammographic and US appearance   总被引:4,自引:0,他引:4  
  相似文献   
87.
Pulmonary histiocytosis X: comparison of radiographic and CT findings   总被引:6,自引:0,他引:6  
The authors retrospectively evaluated radiographs, computed tomographic (CT) scans, and results of pulmonary function tests (when available) for 17 patients with biopsy-proved pulmonary histiocytosis X. In 11 patients, high-resolution CT was used. In 12 patients, CT demonstrated cystic air spaces, usually less than 10 mm in diameter. In three of these 12, cysts were the only abnormality, but in six others, nodules (usually less than 5 mm in diameter) were also present. Two patients had only nodules and one, only emphysema. CT showed that many lesions that appeared reticular on plain radiographs were actually cysts. CT showed no central or peripheral concentration of lesions, but it did reveal that many small nodules were distributed in the centers of secondary lobules around small airways. CT findings correlated better with the diffusing capacity (rho = -0.71) than did the plain radiographic findings (rho = -0.57). Thus, CT was better than radiography at showing the morphology and distribution of lung abnormalities.  相似文献   
88.
Hayden  CK  Jr; Swischuk  LE; Rytting  JE 《Radiology》1987,164(1):131-134
Among 600 infants examined with ultrasound for vomiting, seven (mean age, 3 months) had distinctive features that can be considered diagnostic of gastric ulcer. The findings are thickening of the mucosa (greater than 4 mm) in the antropyloric region, elongation of the antropyloric canal, persistent spasm, and delayed gastric emptying. Two of the infants had slight thickening of the pyloric muscle. Gastrointestinal series or endoscopy demonstrated thickened gastric mucosa and a deformed gastric antrum in all infants, as well as actual ulceration in five.  相似文献   
89.
90.
Tempkin  DL; Ladika  JE 《Radiology》1987,163(1):275-276
An improved catheter for pulmonary arteriography via the antecubital approach is described. The catheter has been used successfully in 56 patients.  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