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   2454篇
  免费   263篇
  国内免费   36篇
耳鼻咽喉   9篇
儿科学   112篇
妇产科学   18篇
基础医学   301篇
口腔科学   119篇
临床医学   217篇
内科学   781篇
皮肤病学   26篇
神经病学   103篇
特种医学   241篇
外科学   375篇
综合类   69篇
一般理论   1篇
预防医学   157篇
眼科学   21篇
药学   131篇
中国医学   2篇
肿瘤学   70篇
  2021年   26篇
  2020年   17篇
  2019年   32篇
  2018年   64篇
  2017年   41篇
  2016年   27篇
  2015年   41篇
  2014年   41篇
  2013年   77篇
  2012年   74篇
  2011年   69篇
  2010年   75篇
  2009年   97篇
  2008年   75篇
  2007年   101篇
  2006年   100篇
  2005年   121篇
  2004年   74篇
  2003年   48篇
  2002年   60篇
  2001年   54篇
  2000年   78篇
  1999年   77篇
  1998年   76篇
  1997年   66篇
  1996年   72篇
  1995年   65篇
  1994年   65篇
  1993年   66篇
  1992年   41篇
  1991年   48篇
  1990年   51篇
  1989年   59篇
  1988年   76篇
  1987年   63篇
  1986年   50篇
  1985年   63篇
  1984年   42篇
  1983年   37篇
  1982年   41篇
  1981年   23篇
  1980年   27篇
  1979年   25篇
  1978年   16篇
  1977年   28篇
  1976年   29篇
  1975年   17篇
  1974年   15篇
  1971年   15篇
  1970年   20篇
排序方式: 共有2753条查询结果,搜索用时 31 毫秒
131.

Background  

Differential adipokine expression in obesity influences the inflammatory milieu, and may explain in part obesity’s negative impact on pancreatic disease. Pancreatic juice analysis may provide a good means to evaluate the local pancreatic inflammatory milieu. The presence of adipokines in pancreatic juice is unknown.  相似文献   
132.
133.
134.
There is a growing chorus of voices in the scientific community calling for greater openness in the sharing of raw data that lead to a publication. In this commentary, we discuss the merits of sharing, common concerns that are raised, and practical issues that arise in developing a sharing policy. We suggest that the cognitive science community discuss the topic and establish a data‐sharing policy.  相似文献   
135.
136.
Molecular phylogeny of Burkholderia pseudomallei   总被引:4,自引:0,他引:4  
In terms of population structure, the species Burkholderia pseudomallei contains both clonal and non-clonal elements. By indexing variation in rRNA loci using the restriction endonuclease BamHI, we found that two ribotypes (types 1 and 3) are predominant in nature. Ribotype 3 is prevalent in Asian countries while ribotype 1 is more widespread. Some disease association was suggested for 4 ribotypes and strains of ribotype 4 were markedly associated with a fatal outcome. DNA macrorestriction (XbaI) profiles resolved by pulsed-field gel electrophoresis revealed great heterogeneity within the prevalent ribotypes and these profiles appeared to be reliable strain markers. Arabinose environmental strains were characterised by BamHI ribotypes that were markedly distinct form clinical and environmental isolates of the arabinose negative phenotype.  相似文献   
137.
Clinical studies of heart failure utilizing losartan, an angiotensin-II receptor antagonist, found that this drug is well tolerated and demonstrates hemodynamic, neurohormonal, and symptomatic improvement. To assess all-cause mortality in heart failure patients treated with losartan, a meta-analysis including 1,896 patients was performed on 6 controlled, double-blind, multiple-dose studies, regardless of sample size or duration of follow-up. A combination of logarithmic (log) odds ratios with a continuity correction was utilized for the meta-analysis. Treatment groups were comparable with regard to demographic characteristics, heart failure characteristics, and concomitant cardiovascular therapies. Concomitant use of open-label angiotensin-converting enzyme (ACE) inhibitors was not allowed in any study. The mean left ventricular ejection fraction obtained in individual studies ranged from 23% to 31%. Seven hundred forty patients were randomized to control therapy and 1,154 patients were randomized to losartan therapy. There were 36 deaths (3.12%) in the losartan groups compared with 47 in the control groups (6.35%) during the double-blind periods. The odds of dying in the losartan groups were 0.51 times (0.31 to 0.81) that of dying in the control groups (p = 0.004). In this analysis, treatment with losartan provided a beneficial effect upon survival. However, because the number of deaths in these studies is relatively small and the follow-up relatively short, a large confirmatory study is needed to assess the mortality benefit of losartan compared with an ACE inhibitor.  相似文献   
138.
A study of tuberculin sensitivity was performed in 353 children aged 4-6 years, all vaccinated at birth with British BCG vaccine. Significant waning of tuberculin reactions with increasing age was found (p < 0.05). In the age group < 4.5 years, the mean tuberculin reaction was 6.6 mm, in the age group 4.5-5.5 years 5.2 mm and in the age group of > 5.5 years 3.5 mm. The number of children with positive reactions (> or = 5 mm) was 165 (40%) and those with strong reactions (> or = 10 mm) 49 (14%). None of the latter children had active tuberculosis during a follow-up period of 12 months. Eighty-three (24%) of the children had no reaction. The children who had been revaccinated with the MPR vaccine against measles, rubella and parotitis (n = 31) had significantly larger tuberculin reactions than the non-revaccinated children. Atopic dermatitis or infections during the preceding six months did not have any significant influence on reaction sizes. Our results demonstrate that the variation in size of tuberculin reactions after BCG vaccination at birth is large. We conclude that tuberculin sensitivity wanes rapidly by the age of 4.0-6.3 years.  相似文献   
139.
Dietary intake during diarrhea in children less than three years of age was estimated from information recorded on illustrated dietary forms used by children's caretakers during the first week of illness in a prospective community-based study of diarrheal diseases in Lima, Peru. The frequency of consumption and the amount consumed of food groups and selected commonly consumed foods were analyzed by the final duration of the diarrheal episode. Cereals were less frequently consumed during the acute phase of diarrheal episodes that ultimately became persistent (>14 days'duration), apparently shortening the duration of the episode by one day (median duration of four days in children not consuming vs three days in children consuming cereals during diarrhea, p <0.02 Kaplan-Meier logrank test). Only roots and tubers (mainly potatoes) were consumed in greater quantity during episodes that became persistent. There was no evidence that consumption of breast milk or non-maternal milk was associated with an alteration in diarrheal duration. This study provides further evidence of the beneficial effects of continuing feeding during diarrhea using foods available at the home level, especially cereals, which are commonly used in the diet of young children.  相似文献   
140.
During a 12-month surveillance period in 1981-1982, Moraxella catarrhalis was detected in cultures from nasopharyngeal aspirates from 76 (17%) of 449 children hospitalized with middle or lower respiratory tract infection. Seroconversion to M. catarrhalis was positive in 4(5%) of the 76 patients with M. catarrhalis present in nasopharyngeal aspirates and in 4(1%) of 373 patients with a negative finding. Although children with respiratory tract infections were often colonized by the organism, this was rarely the infective agent of the middle or lower airways. Four of 8 patients with seroconversion to M. catarrhalis exhibited a concomitant RSV infection. The carriage of this species was more closely associated with parainfluenza virus infections. Serological responses to M. catarrhalis were not associated with acute otitis media, and were also rare in children with pneumonia. It is concluded that bronchopulmonary infections caused by M. catarrhalis are rare in children, and that M. catarrhalis aetiology need not be considered in the selection of antibiotics in cases of community-acquired pneumonia or other infections of the middle or lower respiratory tract affecting primarily healthy children.  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