首页 | 官方网站   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   7583篇
  免费   392篇
  国内免费   53篇
医药卫生   8028篇
  2023年   75篇
  2022年   141篇
  2021年   267篇
  2020年   138篇
  2019年   166篇
  2018年   255篇
  2017年   177篇
  2016年   220篇
  2015年   222篇
  2014年   240篇
  2013年   309篇
  2012年   484篇
  2011年   550篇
  2010年   278篇
  2009年   234篇
  2008年   368篇
  2007年   414篇
  2006年   399篇
  2005年   364篇
  2004年   391篇
  2003年   380篇
  2002年   339篇
  2001年   109篇
  2000年   115篇
  1999年   103篇
  1998年   69篇
  1997年   56篇
  1996年   67篇
  1995年   55篇
  1994年   43篇
  1993年   43篇
  1992年   81篇
  1991年   79篇
  1990年   62篇
  1989年   59篇
  1988年   72篇
  1987年   54篇
  1986年   41篇
  1985年   38篇
  1984年   36篇
  1983年   24篇
  1980年   23篇
  1979年   50篇
  1978年   23篇
  1977年   27篇
  1975年   26篇
  1974年   24篇
  1968年   26篇
  1967年   29篇
  1966年   25篇
排序方式: 共有8028条查询结果,搜索用时 15 毫秒
991.
A simple method of checking for bleeding from the proximal anastomosis site in Bentall operations is described. After suturing a Carbo-Seal prosthesis to the aortic annulus, using a folding-over technique, the left ventricle is filled with cardioplegic solution through the prosthetic valve, and the heart is massaged to visualize possible leaks at the level of the suture.  相似文献   
992.
993.
994.
It is now evident that the cell cycle machinery has a variety of elements negatively regulating cell cycle progression. However, among these negative regulators in cell cycle control, only 4 have been shown to be consistently involved in the development of human cancers as tumor suppressors: Rb (Retinoblastoma susceptibility protein), p53, and two recently identified cyclin-dependent kinase inhibitors, p16INK4A/MTS1 and p15INK4B/MTS2. Because there are functional interrelations among these negative regulators in the cell cycle machinery, it is particularly interesting to investigate the multiplicity of inactivations of these tumor suppressors in human cancers, including leukemias/lymphomas. To address this point, we examined inactivations of these four genes in primary lymphoid malignancies by Southern blot and polymerase chain reaction-single- strand conformation polymorphism analyses. We also analyzed Rb protein expression by Western blot analysis. The p16INK4A and p15INK4B genes were homozygously deleted in 45 and 42 of 230 lymphoid tumor specimens, respectively. Inactivations of the Rb and p53 genes were 27 of 91 and 9 of 173 specimens, respectively. Forty-one (45.1%) of 91 samples examined for inactivations of all four tumor suppressors had one or more abnormalities of these four tumor-suppressor genes, indicating that dysregulation of cell cycle control is important for tumor development. Statistical analysis of interrelations among impairments of these four genes indicated that inactivations of the individual tumor-suppressor genes might occur almost independently. In some patients, disruptions of multiple tumor-suppressor genes occurred; 4 cases with p16INK4A, p15INK4B, and Rb inactivations; 2 cases with p16INK4A, p15INK4B, and p53 inactivations; and 1 case with Rb and p53 inactivations. It is suggested that disruptions of multiple tumor suppressors in a tumor cell confer an additional growth advantage on the tumor.  相似文献   
995.
996.
IntroductionLong-term follow-up studies focusing on the posterior extensor muscles in patients suffering from whiplash injury are scarce. The purpose of this study was to elucidate the changes in the posterior extensor muscles 10 years after whiplash injury.MethodsTwenty-three patients who had suffered from whiplash injury in 1994–1996 and had undergone MRI using a 1.5-T superconductive imager participated in this follow-up study (13 males, 10 females, mean age 51.8 years, mean follow-up 11.5 years). In addition, 60 healthy volunteers who had undergone MRI in the same period were included as controls (36 males, 24 females, mean age 47.8 years, mean follow-up 11.1 years). All participants underwent follow-up MRI. The cross-sectional areas of the deep posterior muscles (CSA) including the multifidus, semispinalis cervicis, semispinalis capitis, and splenius capitis were digitally measured at C3-4, C4-5, and C5-6 using NIH image. The long-term changes in the CSA were compared between the two groups. In addition, correlations between the CSA and cervical spine-related symptoms were evaluated.ResultsThe mean total CSA per patient (the sum of the area from C3-4 to C5-6) was 4811.6 ± 878.4 mm2 in the whiplash patients and 4494.9 ± 1032.7 mm2 in the controls at the initial investigation (p = 0.20), and 5173.4 ± 946.1 mm2 and 4713.0 ± 1065.3 mm2 at the follow-up (p = 0.07). The mean change in CSA over time was 361.8 ± 804.9 mm2 in the whiplash patients and 218.1 ± 520.7 mm2 in the controls (p = 0.34). Ten whiplash patients (43.5%) had neck pain and 11 (47.8%) had shoulder stiffness. However, there was no difference in the change in CSA over time between the symptomatic and asymptomatic patients.ConclusionsThere was no significant difference in the change in CSA between whiplash patients and healthy volunteers after a 10-year follow-up period. In both groups, the cross-sectional area slightly increased at follow-up. In addition, there was no association between the change in CSA and clinical symptoms such as neck and shoulder pain. These results suggest that whiplash injury is not associated with symptomatic atrophy of the posterior cervical muscles over the long term.  相似文献   
997.
In this study, we evaluated the initial clinical experience of early cardiac rehabilitation( CR) for very elderly patients over 85 years old after open heart surgery. From September 2007 to January 2011, 7 consecutive patients (85~90 years, mean 85.9 years, male:female=4:3) who underwent cardiac surgery in our institute were selected. Preoperative activity of daily living (ADL) scores were similar in all cases, and 1 patient used a cane for walking. Preoperative New York Heart Association (NYHA) classification was class III :3, class IV:4. Three patients were admitted for acute congestive heart failure approximately 1 month prior to surgery. Standard open heart surgery using bioprosthesis was performed: 3 patients underwent mitral valve replacement( MVR), 3 had aortic valve replacement( AVR), and 1 had tricuspid valve replacement (TVR). Postoperative clinical course was uneventful, and the mean time of ventilator support was 12.1 hours. Thereafter, early CR was introduced at the intensive care unit( ICU) in all patients, and the mean time of introduction of early rehabilitation was 1.7 days. In the last 4 cases, early CR was done the 1st day following surgery. CR was effectively performed in all cases without any problems or cardiac events, and all patients improved enough to leave their beds at 3~7 days, a mean of 4.4 days after surgery. The mean hospital stay after surgery was 30.9 days( 23 ~ 42 days), almost all patients were able to walk independently, and ADL scores at discharge were improved. Only 2 patients required a cane for walking. Postoperative NYHA classification was improved to class I :5, class II :2. From these results, early CR for very elderly patients over 85 years old could be a safe and effective tool to improve and maintain the ADL and quality of life following surgical intervention.  相似文献   
998.
We report a rare case of pulmonary squamous papilloma. A 42-year-old woman was referred to our hospital complaining of dry cough. A chest computed tomography (CT) showed a mass shadow in the lower lobe of left lung. Serum concentrations of carcinoembryonic antigen (CEA) and squamous cell carcinoma-related antigen (SCC) were elevated to 13.0 ng/ml and 11.8 ng/ml, respectively. The mass was positron emission tomography( PET)-positive, with a maximum standard uptake value( SUVmax) of 11.55, suggesting a malignant neoplasm. Under the guidance of video-assisted thoracoscopy, left basal segmentectomy was performed. Intra-operative diagnosis was a squamous papilloma and no malignancy. Her postoperative course was uneventful. She is currently alive without any sign of recurrence.  相似文献   
999.
1000.
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-23

京公网安备 11010802026262号