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   29806篇
  免费   2781篇
  国内免费   48篇
耳鼻咽喉   221篇
儿科学   1046篇
妇产科学   977篇
基础医学   4229篇
口腔科学   630篇
临床医学   3995篇
内科学   5489篇
皮肤病学   390篇
神经病学   2869篇
特种医学   757篇
外科学   3479篇
综合类   636篇
一般理论   33篇
预防医学   3485篇
眼科学   404篇
药学   2225篇
中国医学   40篇
肿瘤学   1730篇
  2022年   204篇
  2021年   460篇
  2020年   290篇
  2019年   527篇
  2018年   603篇
  2017年   419篇
  2016年   468篇
  2015年   561篇
  2014年   790篇
  2013年   1181篇
  2012年   1721篇
  2011年   1715篇
  2010年   949篇
  2009年   876篇
  2008年   1505篇
  2007年   1669篇
  2006年   1538篇
  2005年   1476篇
  2004年   1511篇
  2003年   1337篇
  2002年   1264篇
  2001年   761篇
  2000年   732篇
  1999年   683篇
  1998年   335篇
  1997年   308篇
  1996年   274篇
  1995年   278篇
  1994年   254篇
  1993年   230篇
  1992年   551篇
  1991年   530篇
  1990年   462篇
  1989年   546篇
  1988年   452篇
  1987年   408篇
  1986年   455篇
  1985年   365篇
  1984年   320篇
  1983年   335篇
  1982年   193篇
  1981年   184篇
  1979年   253篇
  1978年   194篇
  1977年   164篇
  1976年   168篇
  1974年   156篇
  1973年   184篇
  1972年   154篇
  1971年   165篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
971.
Bronchiolitis obliterans syndrome is characterized by fibrotic obliteration of small airways which severely impairs graft function and survival after lung transplantation. Bronchial epithelial cells from the transplanted lung can undergo epithelial to mesenchymal transition and this can be accentuated by activated macrophages. Macrophages demonstrate significant plasticity and change phenotype in response to their microenvironment. In this study we aimed to identify secretory products from macrophages that might be therapeutic targets for limiting the inflammatory accentuation of epithelial to mesenchymal transition in bronchiolitis obliterans syndrome. TNFα, IL‐1β and IL‐8 are elevated in bronchoalveolar lavage from lung transplant patients prior to diagnosis of bronchiolitis obliterans syndrome. Classically activated macrophages secrete more TNFα and IL‐1β than alternatively activated macrophages and dramatically accentuate TGF‐β1‐driven epithelial to mesenchymal transition in bronchial epithelial cells isolated from lung transplant patients. Blocking TNFα, but not IL‐1β, inhibits the accentuation of epithelial to mesenchymal transition. In a pilot unblinded therapeutic intervention in five patients with progressive bronchiolitis obliterans syndrome, anti‐TNFα treatment improved forced expiratory volume in 1 second and 6‐min walk distances in four patients. Our data identify TNFα as a potential new therapeutic target in bronchiolitis obliterans syndrome deserving of a randomized placebo controlled clinical trial.  相似文献   
972.
973.
974.

OBJECTIVE:

To examine treatment indications, efficacy and side effects of oral beta-blockers for the treatment of problematic hemangiomas.

METHODS:

A retrospective review of patients with hemangiomas presenting to the Alberta Children’s Hospital Vascular Birthmark Clinic (Calgary, Alberta) between 2009 and 2011 was conducted. The subset of patients treated with oral beta-blockers was further characterized, investigating indication for treatment, response to treatment, time to resolution of indication, duration of treatment, occurrence of rebound growth and side effects of therapy.

RESULTS:

Between 2009 and 2011, 311 new patients with hemangiomas were seen, of whom 105 were treated with oral beta-blockers. Forty-five patients completed beta-blocker treatment while the remainder continue to receive therapy. Indications for treatment were either functional concerns (68.6%) or disfigurement (31.4%). Functional concerns included ulceration (29.5%), periocular location with potential for visual interference (28.6%), airway interference (4.8%), PHACES syndrome (3.8%), auditory interference (0.95%) and visceral location with congestive heart failure (0.95%). The median age at beta-blocker initiation was 3.3 months; median duration of therapy was 10.6 months; and median maximal treatment dose was 1.5 mg/kg/day for propranolol and 1.6 mg/kg/day for atenolol. Ninety-nine patients (94.3%) responded to therapy with size reduction, colour changes, softened texture and/or healing of ulceration. Rebound growth requiring an additional course of therapy was observed in 23 patients. Side effects from beta-blockers included cool extremities (26.7%), irritability (17.1%), lower gastrointestinal upset (14.3%), emesis (11.4%), hypotension (10.5%), poor feeding (7.6%), lethargy (4.8%), bronchospasm (0.95%) and rash (0.95%). Side effects did not result in complete discontinuation of beta-blocker treatment in any case; however, they prompted a switch to a different beta-blocker preparation in some cases. Resolution of the primary indication, requiring a median time of three months, occurred in 87 individuals (82.9%).

CONCLUSIONS:

Treatment of infantile hemangiomas with oral beta-blocker therapy is highly effective and well tolerated, with more than 94% of patients demonstrating a response to treatment and 90% showing resolution of the primary functional indication for treatment.  相似文献   
975.
976.
977.
978.
Introduction: Nerve cross-sectional area reference values have been reported for many nerves, but there have been few studies in pediatric and geriatric populations. This study was conducted to determine the influence of age on nerve cross-sectional area. Methods: Thirty-two children (3 months to 16 years) and 20 geriatric adults (67–92 years) without known neurologic conditions underwent bilateral ultrasound to measure the area of the following nerves: median at the wrist and forearm; ulnar at the wrist and elbow; radial in the spiral groove; sciatic in the distal thigh; fibular at the knee; tibial at the knee and ankle; and sural at the ankle. Results: In general, nerve cross-sectional area increased with age. Nerve size correlated most closely with age, but a correlation was also seen with body mass index. Conclusions: Nerve cross-sectional area increases with age, which is important to note when using ultrasound to evaluate children and geriatric patients. Muscle Nerve 47: 890–893, 2013  相似文献   
979.
980.
Introduction: Nerve and muscle ultrasound has been studied in several conditions, but validity and reliability have not been assessed systematically. Methods: Nerve cross‐sectional area and muscle thickness were measured ultrasonographically at several sites in 4 cadavers, which were then dissected, and actual measurements were obtained. To assess intrarater and interrater reliability, between 3 and 5 ultrasonographers, with varying experience levels, made repeated measurements on healthy volunteers. Results: Correlation coefficients for nerve and muscle validity were >0.968 (P < 0.001), and for intrarater reliability were >0.901 (P < 0.001) for still and real‐time images. Correlation coefficients for interrater reliability were more varied, but for still images they were all significant at the P < 0.001 (0.542–0.998) level, and for real‐time images they were significant at the P < 0.05 level for half the sites (0.243–0.981). Conclusion: Overall, nerve and muscle ultrasound is a valid and reliable diagnostic imaging technique. Muscle Nerve, 2013  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