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   1642569篇
  免费   111259篇
  国内免费   2568篇
耳鼻咽喉   22712篇
儿科学   53316篇
妇产科学   43175篇
基础医学   242859篇
口腔科学   46104篇
临床医学   147908篇
内科学   309030篇
皮肤病学   37437篇
神经病学   121642篇
特种医学   63270篇
外国民族医学   276篇
外科学   246555篇
综合类   33860篇
现状与发展   3篇
一般理论   404篇
预防医学   117923篇
眼科学   38338篇
药学   129270篇
  10篇
中国医学   4709篇
肿瘤学   97595篇
  2019年   12230篇
  2018年   17621篇
  2017年   13782篇
  2016年   15494篇
  2015年   17278篇
  2014年   23589篇
  2013年   34928篇
  2012年   47282篇
  2011年   49917篇
  2010年   29349篇
  2009年   27634篇
  2008年   46213篇
  2007年   49584篇
  2006年   50454篇
  2005年   47624篇
  2004年   45980篇
  2003年   44054篇
  2002年   42633篇
  2001年   86424篇
  2000年   88320篇
  1999年   73423篇
  1998年   18767篇
  1997年   16320篇
  1996年   16515篇
  1995年   15628篇
  1994年   14183篇
  1993年   13361篇
  1992年   55330篇
  1991年   54050篇
  1990年   52987篇
  1989年   51409篇
  1988年   46514篇
  1987年   45268篇
  1986年   42861篇
  1985年   40211篇
  1984年   29371篇
  1983年   24846篇
  1982年   13762篇
  1979年   26563篇
  1978年   18242篇
  1977年   15951篇
  1976年   14402篇
  1975年   16281篇
  1974年   18970篇
  1973年   18289篇
  1972年   17382篇
  1971年   16272篇
  1970年   15234篇
  1969年   14443篇
  1968年   12971篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
Pulmonary hamartomas are usually an incidental finding and range in size from 1 cm to 8 cm in diameter in various series. We report a case of a massive pulmonary hamartoma (size 25.5 × 17.5 × 6.5 cm and weighing 1134 g) in a 61 year old male who presented with a short history of breathlessness. The tumour was arising from the medial border of the right lung and occupying most of the right chest extending in to the anterior mediastinum. The tumour was compressing the right lung and there was no evidence of infiltration into the surrounding structures. It was successfully treated by surgical resection and final histology was pulmonary hamartoma with predominantly adipose and leiomyomatous differentiation.  相似文献   
42.
OBJECTIVE: To explore the presence and grade of denervation in three mimic muscles in facial nerve palsy. METHODS: The frontalis, orbicularis oculi (OO), and mentalis muscles were explored in 54 patients with Bell's palsy, after 30 days from the beginning of symptoms. Concentric needle electromyography, including fibrillation detection, was performed in the three muscles on the affected side. Compound muscle action potentials (CMAP) were recorded on both sides and a CMAP ratio was calculated from each muscle. The House-Brackman scale was used to assess the initial clinical evaluation and the follow-up until recovery. RESULTS: Fibrillation was recorded in 32 patients on the 30th day after the onset and was present in 100% of mentalis and in 90% of frontalis, but in only 34% of OO, a statistically significant difference. The grade of fibrillation in OO was also statistically lower from those in the other two muscles. The 32 patients were grouped according to the presence (A) or not (B) of fibrillation in OO. In group A, CMAP ratios (affected/normal side) did not differ significantly among the three muscles. However, in group B they were significantly greater in OO and frontalis than in mentalis. In between-group comparison, group B muscles had significantly higher CMAP ratios, lower degree of fibrillation, and better functional recovery. CONCLUSION: In facial palsy, the presence and grade of fibrillation in OO are lower than in frontalis and mentalis muscles and prognosis is more favorable for the non-fibrillating OO group of patients.  相似文献   
43.
Although studies have documented underuse of controller medications and overuse of short-acting inhaled ss(2)-agonist among children with persistent asthma in disadvantaged communities, the persistence of oral ss(2)-agonist use in pediatric practice has not been studied since inhaled short-acting ss(2)-agonists became widespread. We describe medications used to treat asthma among children 3 to 5 years of age at 10 Head Start and other subsidized preschool centers in East and Central Harlem, New York City. We interviewed 149 parents/guardians of children who were identified as having probable asthma based on physician's diagnosis, persistent symptoms, hospitalization, and medication use. We classified 86 of the 149 children (58%) as having current persistent asthma. Only 15 of them (17%) were reported to have used controller medications at least 5 days/week in the last 4 weeks-only 2 of whom used inhaled corticosteroids. By contrast, 53 children (62%) used oral ss(2)-agonist in the last 4 weeks, often (72%) in conjunction with nebulized or inhaled short-acting ss(2)-agonist. Use of oral ss(2)-agonist was associated with more severe symptoms. This study documents the continued widespread use of oral ss(2)-agonist for treatment of children in a low-income community with high prevalence of asthma.  相似文献   
44.
45.
46.
Vitiligo and psoriasis are both common skin disorders. However, psoriasis strictly confined to pre-existing vitiligo areas is rare and suggests a causal relationship. We report here on two patients with a strict anatomical colocalization of vitiligo and psoriasis. The histopathological examinations showed typical changes for both diseases together with a dense infiltrate of CD4+ and CD8+ T cells. By immunohistochemistry, intracytoplasmatic granzyme B and tumour necrosis factor alpha (TNF-alpha) were detected within the T-cell population, suggesting the functional activity of these cells and the creation of a local T helper 1 (Th1)-cytokine milieu. Additionally, in one patient we could identify anti-melanocytic T cells by tetramer staining and enzyme-linked immunospot (ELISPOT) analysis. These skin-infiltrating lymphocytes might trigger, by the local production of Th-1 cytokines such as TNF-alpha and interferon-gamma (IFN-gamma), the eruption of psoriatic plaques in patients with a genetic predisposition for psoriasis.  相似文献   
47.
目的:描述胚胎种植前遗传诊断在1例携带Ⅰ型白细胞黏附缺陷病(LAD-1)携带者并完成健康妊娠夫妇中的应用。设计:病例报道。机构:大学医院生殖中心。患者:1例男女双方都是LAD-1携带者的夫妇,女方CD18基因的外显子4携带有G400A置换,男方的外显子5携带有C562T置换。干预:标准体外受精(IVF)后第3天行卵裂期活检和分裂球遗传分析以检测2处突变以及21号染色体标记物。主要观察指标:1个未罹患LAD-1婴儿的出生。结果:得到15个卵母细胞,其中10个受精。8个胚胎适宜胚胎活组织检查。  相似文献   
48.
Using the SF-12 to measure physical and mental functioning, the authors examine the intra-individual changes in health-related quality of life (HRQOL) 6 months post-discharge for depressed older adults. In addition, they examine three sets of predictors that might influence these changes. The sample of depressed older adults was recruited from an inpatient geropsychiatry unit. Although their physical and mental health scores on the SF-12 were lower than comparable norms, the sample showed an average increase in their mental functioning but a decrease in the physical functioning over the 6 months. Negative life-events were significant predictors of people who reported no change in their mental health functioning and decreases in their physical health functioning. Interestingly, those who experienced positive life events were more likely to report declines and younger participants were more likely to report no change in their physical functioning. The findings indicate that the effects of depression on HRQOL can have enduring effects on a sample of previously hospitalized older adults. The significance of life event changes might signify the importance of taking into account non-traditional areas of medical interventions. Further, the findings indicate the usefulness of the SF-12 quantifying HRQOL outcomes.  相似文献   
49.
50.
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