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   538篇
  免费   17篇
  国内免费   38篇
儿科学   10篇
妇产科学   2篇
基础医学   44篇
口腔科学   2篇
临床医学   41篇
内科学   234篇
皮肤病学   4篇
神经病学   24篇
特种医学   104篇
外科学   19篇
综合类   16篇
预防医学   32篇
药学   46篇
中国医学   1篇
肿瘤学   14篇
  2021年   8篇
  2020年   4篇
  2019年   10篇
  2018年   6篇
  2017年   4篇
  2016年   4篇
  2015年   6篇
  2014年   9篇
  2013年   9篇
  2012年   13篇
  2011年   20篇
  2010年   12篇
  2009年   15篇
  2008年   21篇
  2007年   31篇
  2006年   22篇
  2005年   22篇
  2004年   21篇
  2003年   15篇
  2002年   14篇
  2001年   21篇
  2000年   20篇
  1999年   11篇
  1998年   21篇
  1997年   8篇
  1996年   11篇
  1995年   20篇
  1994年   11篇
  1993年   13篇
  1992年   6篇
  1991年   7篇
  1990年   16篇
  1989年   21篇
  1988年   13篇
  1987年   11篇
  1986年   13篇
  1985年   10篇
  1984年   6篇
  1983年   11篇
  1982年   5篇
  1981年   11篇
  1980年   5篇
  1979年   4篇
  1978年   11篇
  1977年   6篇
  1976年   8篇
  1973年   4篇
  1972年   4篇
  1971年   3篇
  1970年   3篇
排序方式: 共有593条查询结果,搜索用时 15 毫秒
121.
人白血病HL60细胞的分化状态对细胞凋亡的影响   总被引:2,自引:0,他引:2  
用细胞培养和流式细胞术等方法,研究人白血病HL60细胞诱导分化后,对三尖杉酯碱(Har)和喜树碱(Cam)诱导细胞凋亡的影响。结果表明,12-豆蔻酰及13-乙酸佛波酯以16nmol·L-1浓度处理HL60细胞24h,细胞向单核/巨噬细胞方向分化,阻断于G1期;分化细胞抗Har和Cam诱导的细胞凋亡,但其c-myc基因的表达无变化。1.4%二甲基亚砜处理HL60细胞48h,细胞向粒细胞方向分化,阻断于G1期;分化细胞抗Cam,而不抗Har诱导的细胞凋亡;分化细胞的c-myc基因表达明显下降。结果提示,人白血病HL60细胞的分化状态,明显影响三尖杉酯碱和喜树碱诱导的细胞凋亡,但可能与c-myc基因的表达变化无关。  相似文献   
122.
该指南是英国皮肤科医师协会针对皮肤科医生制定的 ,反映了当前文献报道中的最新研究资料。在解释这些资料时应慎重 ,因为未来的研究可能会改变现有的结论或推荐方案。在应用该指南时 ,需因人而异 ,因地制宜。遵守指南并不能确保万无一失 ,因此对实施指南时的偏离不应都归咎于疏忽 (该指南并不能保证面面俱到 ,在实际应用中可加以变通 )。简介 :甲真菌病是最常见的皮肤病之一。英国对 10 0 0 0人进行的一项大规模问卷调查显示发病率为 2 71%。芬兰和美国最近的真菌学对照调查表明 ,发病率为 7%~ 10 %。甲真菌病发病率的升高和有效抗真菌新…  相似文献   
123.
Middleton  WD; Melson  GL 《Radiology》1989,173(2):427-429
To determine the appearance of artifactual renal duplication in ultrasound (US) imaging, the authors analyzed 22 examples of such duplication in 20 patients. The artifact appeared as a duplication of the collecting system in 18, as a suprarenal mass in three, and as upper-pole cortical thickening in one. It occurred in the left kidney in 15 patients, in the right kidney in three, and bilaterally in two. To determine the frequency of the artifact, 50 additional patients were scanned. It was identified in eight of these patients. Imaging characteristics and the results of in vitro modeling proved the artifact was due to sound beam refraction between the lower pole of the spleen or liver and adjacent fat. This artifact is much more common in the left kidney and occurs more frequently in obese patients. Knowledge of the appearance and cause of this artifact should help radiologists avoid diagnostic errors.  相似文献   
124.
A new class of radio frequency (RF) coils for magnetic resonance (MR) imaging and spectroscopy is introduced. The coils consist of two loop-gap resonators of equal diameters positioned along a common axis. They are tuned to the mode in which the current in the two loops flows in opposite directions. These coils are "decoupled" from a uniform excitation field of arbitrary orientation (including circularly polarized fields) by intrinsic decoupling and by means of back-to-back fast recovery diodes. Measurements made with the coils and a phantom saline tank indicate that the signal-to-noise ratio obtainable with these coils is almost identical to that obtained with single loops. Imaging of several anatomic areas, including knee, wrist, and shoulder, has been performed with a 1.5-T MR system that uses circularly polarized RF. A small series of patients with torn rotator cuffs underwent imaging. Difficulties in establishing the diagnosis with MR imaging because of anatomic complexity are illustrated. The value of pulse sequences with long repetition times to increase the signal intensity of fluid in the joint is shown.  相似文献   
125.
Objective: To examine trends in leisure time physical activity and inactivity in Australians aged 15 years or older from 1989 to 2011. Method: We used data from six Australian National Health Surveys conducted from 1989/90 to 2011/12 in which physical activity was assessed using comparable questions. Analyses examined trends in the prevalence of sufficient physical activity (≥150 minutes/week moderate‐to‐vigorous physical activity) and of inactivity (<30 minutes/week moderate‐to‐vigorous physical activity). Results: The proportion of sufficiently active adults was 39.2% in 1989 and 40.7% in 2011 with an overall declining trend of 0.2% per year (p=0.012). The prevalence of inactivity was 38.7% in 1989 and 37.3% in 2011; the overall time trend by year was stable (OR=0.999, p=0.242). In women, sufficient physical activity decreased by 0.3% per year from 35.5% in 1989 (p=0.025); inactivity increased from 39.5% by 0.3% per year (p=0.004). In men, sufficient physical activity prevalence was 43.1% in 1989 with a steady trend; inactivity decreased from 37.9% by 0.5% per year (p<0.0001). Conclusions: The prevalence of sufficient physical activity remains low and inactivity high. Women appear to be a key target group for intervention. Public health efforts have been ineffective over two decades for improving physical activity among Australian adults. Implications for public health: This research supports calls for a national physical activity action plan given the multitude of benefits from sufficient physical activity. Maintenance of consistent physical activity questions in future National Health Surveys will facilitate long term tracking of physical activity levels in the Australian population.  相似文献   
126.
Startle disease or hyperekplexia (STHE; MIM 149400) is a rare disorder that is characterized by marked muscular hypertonia in infancy and an exaggerated startle response to unexpected acoustic or tactile stimuli. Mutations in the gene encoding the α‐1 subunit of the inhibitory glycine receptor (GLRA1) were reported as causes of STHE. Recently, we encountered a Korean male infant with generalized stiffness that was observed from the first 3 days of life. The abnormal startle response was evident from the fourth week of life, and he showed marked improvement in the startle response and muscle hypertonia after being administered phenobarbital and clonazepam. Direct sequencing analysis of the infant and his parents revealed a de novo variation (c.910A>C) in the GLRA1 gene, resulting in a novel Lys304Gln missense mutation. © 2007 Movement Disorder Society  相似文献   
127.
Digestive Diseases and Sciences - Helicobacter pylori (H. pylori) infects ~ 35% of Americans and can lead to serious sequelae if left untreated. Growing evidence indicates that...  相似文献   
128.
129.
130.
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