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   6462篇
  免费   427篇
  国内免费   29篇
耳鼻咽喉   38篇
儿科学   122篇
妇产科学   105篇
基础医学   919篇
口腔科学   195篇
临床医学   540篇
内科学   1407篇
皮肤病学   120篇
神经病学   711篇
特种医学   205篇
外科学   1121篇
综合类   36篇
一般理论   3篇
预防医学   388篇
眼科学   101篇
药学   453篇
中国医学   7篇
肿瘤学   447篇
  2023年   42篇
  2022年   77篇
  2021年   177篇
  2020年   105篇
  2019年   157篇
  2018年   190篇
  2017年   151篇
  2016年   146篇
  2015年   166篇
  2014年   263篇
  2013年   266篇
  2012年   476篇
  2011年   511篇
  2010年   246篇
  2009年   231篇
  2008年   425篇
  2007年   401篇
  2006年   365篇
  2005年   359篇
  2004年   286篇
  2003年   287篇
  2002年   288篇
  2001年   102篇
  2000年   75篇
  1999年   83篇
  1998年   87篇
  1997年   50篇
  1996年   52篇
  1995年   44篇
  1994年   36篇
  1993年   30篇
  1992年   42篇
  1991年   61篇
  1990年   51篇
  1989年   39篇
  1988年   37篇
  1987年   37篇
  1986年   47篇
  1985年   66篇
  1984年   32篇
  1983年   27篇
  1982年   26篇
  1981年   19篇
  1980年   24篇
  1979年   36篇
  1978年   16篇
  1975年   17篇
  1974年   21篇
  1973年   21篇
  1969年   14篇
排序方式: 共有6918条查询结果,搜索用时 15 毫秒
1.
To determine percent of patients without malignancy and ≤ 40 years of age with high cumulative radiation doses through recurrent CT exams and assess imaging appropriateness. From the cohort of patients who received cumulative effective dose (CED) of ≥ 100 mSv over a 5-year period, a sub-set was identified with non-malignant disease. The top 50 clinical indications leading to multiple CTs were determined. Clinical decision support (CDS) system scores were analyzed using a widely adopted standard of 1–3 (red) as “not usually appropriate,” 4–6 (yellow) “may or may not be appropriate,” and 7–9 (green) “usually appropriate.” Clinicians reviewed patient records to assess compliance with appropriate use criteria (AUC). 9.6% of patients in our series were with non-malignant conditions and 1.4% with age ≤ 40 years. CDS scores (rounded) were 2% red, 38% yellow, 27% green, and 33% unscored CTs. Clinical society guidelines for CT exams, wherever available, were followed in 87.5 to 100% of cases. AUCs were not available for several clinical indications as also referral guidelines for serial CT imaging. More than half of CT exams were unrelated to follow-up of a primary chronic disease. We are faced with a situation wherein patients in age ≤ 40 years require or are thought to require many CT exams over the course of a few years but the radiation risk creates concern. There is a fair number of conditions for which AUC are not available. Suggested solutions include development of CT scanners with lesser radiation dose and further development of appropriateness criteria.  相似文献   
2.
3.
Aggressive behavior linked to corticotropin-reactive autoantibodies.   总被引:3,自引:0,他引:3  
BACKGROUND: Altered stress response is characteristic for subjects with abnormal aggressive and antisocial behavior, but the underlying biological mechanisms are unclear. We hypothesized that autoantibodies (autoAbs) directed against several stress-related neurohormones may exist in aggressive subjects. METHODS: Using enzyme-linked immunosorbent assay, we studied whether autoAbs directed against corticotropin (ACTH), alpha-melanocyte-stimulating hormone (alpha-MSH), oxytocin, and vasopressin are present in serum of male subjects with conduct disorder and prisoners with history of violence. Healthy blood donors served as control subjects. RESULTS: Both conduct disorder and prisoners groups displayed strongly increased levels of ACTH-reactive immunoglobulin G (IgG) and immunoglobulin M (IgM) autoAbs compared with control subjects. Levels of oxytocin-reactive IgM autoAbs were slightly increased in both groups of aggressive subjects, whereas levels of vasopressin-reactive IgG and IgM autoAbs were lower only in conduct disorder. No differences in the levels of alpha-MSH-reactive autoAbs were found between aggressive and control subjects. CONCLUSIONS: High levels of ACTH-reactive autoAbs as well as altered levels of oxytocin- and vasopressin-reactive autoAbs found in aggressive subjects may interfere with the neuroendocrine mechanisms of stress and motivated behavior. Our data suggest a new biological mechanism of human aggressive behavior that involves autoAbs directed against several stress-related neurohormones.  相似文献   
4.
5.
6.
We would like to thank Professor Erdem Kasikcioglu for his interestin our article. In response to the initial question of why exhaustivephysical activity suppresses diastolic function,  相似文献   
7.
Between October 2001 and August 2002, 30 hospital patients became infected or colonised by a multiresistant (including to carbapenems) epidemic strain of Acinetobacter baumannii (AbMR) in a hospital outbreak. This study analysed the risk-factors associated with acquisition of this epidemic strain and investigated the prognosis of patients infected by AbMR, with the aim of elucidating factors which lead to mortality. A case-control study of the acquisition of AbMR in patients infected or colonised in the hospital outbreak was performed. Independent risk-factors leading to death were studied by logistic regression analysis. Multivariate analysis of the risk-factors for colonisation/infection with AbMR revealed an independent association with the presence of an arterial catheter (OR, 1.13; 95% CI, 1.03-1.25) and administration of imipenem as monotherapy (OR, 11.12; 95% CI, 2.33-53.09). Multivariate analysis of the prognostic features leading to mortality revealed a significant association with hypotension or shock (OR, 24.63; 95% CI, 1.56-387.56) at the time of bacterial isolation.  相似文献   
8.
9.
10.
For 3 months in 1969 a family in the United States that included a pregnant mother consumed pork containing methylmercury. Children, aged 20, 13, and 8 years and a neonate, developed severe neurological signs. Twenty-two years later, the 2 oldest had cortical blindness or constricted visual fields, diminished hand proprioception, choreoathetosis, and atentional deficits. Magnetic resonance images showed tissue loss in the calcarine and parietal cortices and cerebellar folia. The youngest had quadriplegia, blindness, and severe mental retradation until their deaths. The brain of the 8-year-old who died at age 30 showed cortical atrophy, neuronal loss, and gliosis, most pronounced in the paracentral and parietooccipital regions. The total mercury level in formalin-fixed, left occipital cortex was 1,974 ng/gm as measured by atomic absorption. Regional brain mercury levels correlated with extent of brain damage. A control patient had 38.5 ng of mercury/gm in the occipital cortex. Systemic organs in the patient and a control subject had comparable mercury levels. In mercury-intoxicated rats, we found that only 5 to 10% of total brain mercury was lost by formalin fixation. Brain inorganic mercury in the patient ranged from 82 to 100%. Since inorganic mercury crosses the blood-brain barrier poorly, biotransformation of methyl to inorganic mercury may have occurred after methylmercury crossed the blood-brain barrier, accounting for its persistence in brain and causing part of the brain damage.  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