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   118309篇
  免费   30358篇
  国内免费   1131篇
耳鼻咽喉   2540篇
儿科学   3259篇
妇产科学   2823篇
基础医学   5743篇
口腔科学   5413篇
临床医学   28929篇
内科学   28092篇
皮肤病学   3637篇
神经病学   14339篇
特种医学   4039篇
外科学   19274篇
综合类   268篇
现状与发展   40篇
一般理论   26篇
预防医学   15870篇
眼科学   2490篇
药学   2659篇
  1篇
中国医学   61篇
肿瘤学   10295篇
  2024年   753篇
  2023年   5177篇
  2022年   1428篇
  2021年   3302篇
  2020年   5680篇
  2019年   2518篇
  2018年   7453篇
  2017年   7722篇
  2016年   8330篇
  2015年   8580篇
  2014年   11059篇
  2013年   13222篇
  2012年   5358篇
  2011年   5253篇
  2010年   7669篇
  2009年   9901篇
  2008年   4879篇
  2007年   3873篇
  2006年   5010篇
  2005年   3468篇
  2004年   2796篇
  2003年   2364篇
  2002年   2121篇
  2001年   1931篇
  2000年   1223篇
  1999年   1803篇
  1998年   2241篇
  1997年   2018篇
  1996年   2072篇
  1995年   1774篇
  1994年   1182篇
  1993年   998篇
  1992年   798篇
  1991年   699篇
  1990年   562篇
  1989年   577篇
  1988年   535篇
  1987年   411篇
  1986年   388篇
  1985年   333篇
  1984年   310篇
  1983年   364篇
  1982年   287篇
  1981年   240篇
  1980年   166篇
  1979年   95篇
  1978年   142篇
  1977年   139篇
  1976年   107篇
  1974年   92篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Although previous studies have shown successful treatment of persistent diarrhea (PD) with the use of yogurt-based diets, some recent ones speculate the need of special formulas for the nutritional management of PD complicated cases. In the present study, we tested the hypothesis that the consumption of 3 lactose-free diets, with different degrees of complexity, is associated with lower stool output and shorter duration of diarrhea when compared with the use of a yogurt-based one on the nutritional management of PD. A total of 154 male infants, aged between 1 and 30 months, with PD and with or without dehydration, were randomly assigned to 1 of 4 treatment groups. Throughout the study, the patients were placed in a metabolic unit; their body weights and intakes of oral rehydration solution, water, and formula diets, in addition to outputs of stool, urine, and vomit, were measured and recorded at 24-hour intervals. Four different diets were used in this study: diet 1, yogurt-based formula; diet 2, soy-based formula; diet 3, hydrolyzed protein-based formula; and diet 4, amino acid–based formula. Throughout the study, only these formula diets were fed to the children. The data showed that children fed the yogurt-based diet (diet 1) or the amino acid–based diet (diet 4) had a significant reduction in stool output and in the duration of diarrhea. The use of an inexpensive and worldwide-available yogurt-based diet is recommended as the first choice for the nutritional management of mild to moderate PD. For the few complicated PD cases, when available, a more complex amino acid–based diet should be reserved for the nutritional management of these unresponsive and severe presentations. Soy-based or casein-based diets do not offer any specific advantage or benefits and do not seem to have a place in the management of PD.  相似文献   
62.
63.
64.
65.
Milos Jesenak  MD  PhD    Peter Banovcin  MD  PhD    Zuzana Rennerova  MD  PhD    Lubica Jakusova  MD  PhD    Zuzana Havlicekova  MD  PhD    Vladimir Pohanka  MD  PhD  MPH  FCCP    Maria Pia Villa  MD  PhD    Roberto Ronchetti  MD  PhD 《International journal of dermatology》2009,48(9):941-946
Background  The atopy patch test (APT) is no longer an experimental method; it is increasingly being used as a standard diagnostic tool for the characterization of patients with aeroallergen- and food-triggered disorders. Some technical aspects of this test still remain to be answered. We aimed to study the reproducibility of this test over time in the general child population.
Methods  In a general population of 118 children, we investigated the reproducibility of duplicate APTs with four food allergens in their native form, which were repeated at set intervals from the first test: 7 days (group 1), 14 days (group 2), and 21 days (group 3).
Results  We observed very poor reproducibility on both sides of the back in all three studied subgroups. The reproducibility rates and Cohen's κ values did not improve when we did not consider the side of the back. There were no differences in the prevalence of atopy between the subjects with reproducible and nonreproducible APT results. All three groups studied showed no difference in the prevalence rates of atopy. There was no relationship between APT and skin prick test positivity for the same allergen. Questionnaire-derived data about previous food-related reactions did not help in the evaluation of the doubtful nonreproducible APT results with food allergens.
Conclusions  Our results show that the reproducibility of food APTs is poor and unsatisfactory over time, and there is an urgent need for the development of optimal, stable, and good-quality APT testing substances.  相似文献   
66.
Iron deficiency may exacerbate symptoms in the Restless Legs Syndrome (RLS). We investigated the effect of intravenous iron sucrose or placebo on symptoms in patients with RLS and mild to moderate iron deficit. Sixty patients with primary RLS (seven males, age 46 (9) years, S‐ferritin ≤45 μg/L) recruited from a cohort of 231 patients were randomly assigned in a 12‐months double‐blind, multi‐centre study of iron sucrose 1000 mg (n = 29) or saline (n = 31). The primary efficacy variable was the RLS severity scale (IRLS) score at week 11. Median IRLS score decreased from 24 to 7 (week 11) after iron sucrose and from 26 to 17 after placebo (P = 0.123, N.S. for between treatment comparison). The corresponding scores at week 7 were 12 and 20 in the two groups (P = 0.017). Drop out rate because of lack of efficacy at 12 months was 19/31 after placebo and 5/29 patients after iron sucrose (Kaplan–Meier estimate, log rank test P = 0.0006) suggesting an iron induced superior long term RLS symptom control. Iron sucrose was well tolerated. This study showed a lack of superiority of iron sucrose at 11 weeks but found evidence that iron sucrose reduced RLS symptoms both in the acute phase (7 weeks) and during long‐term follow up in patients with variable degree of iron deficiency. Further studies on target patient groups, dosing and dosing intervals are warranted before iron sucrose could be considered for treatment of iron deficient patients with RLS. © 2009 Movement Disorder Society  相似文献   
67.
68.
This study evaluated the effects of tobacco Purchase, Use and Possession (PUP) laws on student perceptions of adolescent tobacco use within towns and schools. Twenty‐four towns were randomly assigned into two conditions, the experimental condition (E PUP) involved efforts to increase both PUP law enforcement and reduce minors' access to commercial sources of tobacco, whereas the control condition (C) focused only on efforts to reduce minors' access to commercial sources of tobacco. A hierarchical linear modeling analytical approach was selected due to the multilevel data and nested design. The present study found that over time, youth in the experimental PUP condition observed less youth tobacco usage at school and in their town, and perceived lower rates of tobacco among their peers at school and among friends than youth in the control condition. The findings suggest that PUP law enforcement might be used to strengthen community norms against youth tobacco use.  相似文献   
69.
70.
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