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   1783篇
  免费   96篇
  国内免费   37篇
耳鼻咽喉   52篇
儿科学   93篇
妇产科学   17篇
基础医学   143篇
口腔科学   40篇
临床医学   201篇
内科学   347篇
皮肤病学   85篇
神经病学   245篇
特种医学   210篇
外科学   133篇
综合类   50篇
预防医学   94篇
眼科学   38篇
药学   52篇
中国医学   1篇
肿瘤学   115篇
  2021年   23篇
  2020年   6篇
  2019年   19篇
  2018年   22篇
  2017年   25篇
  2016年   24篇
  2015年   32篇
  2014年   28篇
  2013年   63篇
  2012年   60篇
  2011年   41篇
  2010年   63篇
  2009年   54篇
  2008年   51篇
  2007年   55篇
  2006年   53篇
  2005年   62篇
  2004年   40篇
  2003年   33篇
  2002年   34篇
  2001年   40篇
  2000年   39篇
  1999年   48篇
  1998年   61篇
  1997年   55篇
  1996年   55篇
  1995年   40篇
  1994年   43篇
  1993年   42篇
  1992年   45篇
  1991年   40篇
  1990年   35篇
  1989年   62篇
  1988年   74篇
  1987年   47篇
  1986年   52篇
  1985年   58篇
  1984年   21篇
  1983年   21篇
  1982年   9篇
  1981年   13篇
  1980年   9篇
  1979年   18篇
  1978年   10篇
  1977年   8篇
  1976年   15篇
  1975年   13篇
  1974年   11篇
  1973年   7篇
  1970年   7篇
排序方式: 共有1916条查询结果,搜索用时 33 毫秒
71.
72.
73.
Kinnison  ML; Powe  NR; Steinberg  EP 《Radiology》1989,170(2):381-389
The authors reviewed 100 randomized controlled trials (RCTs) conducted in humans to compare safety or efficacy of new low-osmolality contrast media (LOM) with that of high-osmolality contrast media (HOM). Findings of the 43 RCTs judged to be of the highest quality suggest that the efficacy of LOM in imaging is equal or superior to that of HOM for all routes of administration. Heat sensation occurred less often with LOM for all routes and pain occurred less often with LOM for intraarterial routes. No differences were seen in nephrotoxicity or in frequency of nausea, vomiting, urticaria, bronchospasm, laboratory test abnormalities, or neurologic events. Greater cardiovascular changes were seen with HOM, including increased or decreased heart rate, increased left ventricular end-diastolic pressure, decreased systolic pressure, and QT prolongation, depending on route of administration. To demonstrate whether a reduction in clinically significant adverse outcomes truly occurs with LOM, trials will need to enlist larger numbers of patients and employ appropriate outcome measures. Future trials should stratify patients according to their risk of adverse reactions to provide better information about benefits of LOM in low- versus high-risk patients.  相似文献   
74.
75.
Effect of antenatal steroid administration on the fetal biophysical profile   总被引:2,自引:0,他引:2  
PURPOSE: Our objective was to determine whether antenatal steroid administration affects the biophysical profile score in fetuses. METHODS: A prospective study was conducted in 84 fetuses between 28 and 34 weeks' menstrual age at risk of preterm delivery. Two intramuscular injections of 12 mg of betamethasone were given to the mother 24 hours apart. All fetuses underwent biophysical profile testing prior to and between 24 and 48 hours after steroid administration. Biophysical profiles (including nonstress tests) were evaluated by two maternal-fetal medicine specialists blinded to the timing of steroid administration. Neonatal outcome, including Apgar score, menstrual age at delivery, admission to and length of stay in the neonatal intensive care unit, and mortality, was analyzed in all subjects. RESULTS: In 31 (37%; 95 confidence interval, 26.6-47.2%) of 84 cases, the biophysical profile score decreased at least 2 points after steroid administration. The most commonly affected variables were fetal breathing and the nonstress test. There was no significant difference in the neonatal outcome between the fetuses whose biophysical profile decreased and those whose did not. CONCLUSIONS: Biophysical profile scores were decreased in more than one third of fetuses within 48 hours of antenatal steroid administration, but neonatal outcome was not affected. Knowledge of this occurrence could avoid incorrect decision making regarding fetal well-being.  相似文献   
76.
This study presents the results of a 20 year review of maxillary sinus wash-outs performed on children. The results show a decreasing incidence of purulent sinusitis over the study period. Only 17 per cent of antral wash-outs undertaken yielded pus, indicating that surgical practice has failed to adequately take account of the changing disease incidence.  相似文献   
77.
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   
78.
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   
79.
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   
80.
Objective: To determine the immunity to hepatitis B, poliomyelitis and measles in fully vaccinated Aboriginal and Torres Strait Island children in north Queensland.
Methodology: A cross-sectional survey of immunity in a sample of children; 101 fully vaccinated Aboriginal and Torres Strait Island children, with a median age of 24.5 months, from 10 communities in North Queensland participated in this study. The main outcome measures were the prevalence of adequate antibody levels against hepatitis B, poliomyelitis and measles.
Results: Only 54% (95% Cl 44–63%) of the children had adequate immunity (10 m iu/mL) to hepatitis B, and one child had been infected despite vaccination. Although all the children (95% Cl 96–100%) had adequate immunity (i.e. neutralizing antibodies at a dilution of 1:8) to poliovirus 2, only 93% (95% Cl 86–96%) and 60% (95% Cl 50–69%) had adequate immunity to polioviruses 1 and 3, respectively. Nearly all (96%; 95% Cl 90–98%) of the children had adequate immunity (i.e. detectable IgG antibody) to measles.
Conclusions: Although a relatively low proportion of the children had adequate antibody levels against hepatitis B the clinical significance of this observation is uncertain. Further studies are needed to determine whether fully vaccinated Torres Strait Island children have been adequately protected and whether they require a booster dose of hepatitis B vaccine. A substantial proportion of fully vaccinated Aboriginal and Torres Strait Island children are inadequately protected against poliomyelitis, and therefore any such child with acute flaccid paralysis should be investigated fully for poliomyelitis. Vaccinated Aboriginal and Torres Strait Island children are well protected against measles, as are other Australian 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