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   3377002篇
  免费   268687篇
  国内免费   6048篇
耳鼻咽喉   48568篇
儿科学   107704篇
妇产科学   93115篇
基础医学   475557篇
口腔科学   99556篇
临床医学   307145篇
内科学   654058篇
皮肤病学   70442篇
神经病学   280956篇
特种医学   134404篇
外国民族医学   1247篇
外科学   507327篇
综合类   83074篇
现状与发展   4篇
一般理论   1430篇
预防医学   272678篇
眼科学   79828篇
药学   252597篇
  7篇
中国医学   6256篇
肿瘤学   175784篇
  2018年   33676篇
  2016年   28966篇
  2015年   33115篇
  2014年   47009篇
  2013年   71892篇
  2012年   96640篇
  2011年   102238篇
  2010年   60388篇
  2009年   57643篇
  2008年   97270篇
  2007年   103044篇
  2006年   104217篇
  2005年   101358篇
  2004年   98371篇
  2003年   94676篇
  2002年   93472篇
  2001年   153593篇
  2000年   159055篇
  1999年   135054篇
  1998年   39194篇
  1997年   35531篇
  1996年   35031篇
  1995年   33992篇
  1994年   31959篇
  1993年   29893篇
  1992年   109734篇
  1991年   106119篇
  1990年   103006篇
  1989年   99509篇
  1988年   92489篇
  1987年   91253篇
  1986年   86687篇
  1985年   83103篇
  1984年   63047篇
  1983年   54108篇
  1982年   32701篇
  1981年   29210篇
  1980年   27528篇
  1979年   59881篇
  1978年   42119篇
  1977年   35544篇
  1976年   33338篇
  1975年   35294篇
  1974年   43525篇
  1973年   41582篇
  1972年   38729篇
  1971年   36055篇
  1970年   33665篇
  1969年   31440篇
  1968年   28674篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
52.
In cystic fibrosis (CF), perturbations of total daily energy expenditure (TDEE) may be a major determinant of altered nutrition and growth. Measurement of TDEE is problematic, though the flex-heart rate method (FHRM) provides a close estimation of TDEE, as compared to the cost-prohibitive, gold standard, the double-labeled water method, and permits estimates of the energy cost of daily activities (ECA) above resting energy expenditure (REE). We hypothesize that alterations in ECA affects TDEE in CF. PURPOSE: To measure components of TDEE in adolescents with CF and normal lung function compared with controls, and to determine whether ECA can be improved by diet and exercise. METHODS: Clinically stable CF subjects (aged 9-13, n=12) and age- and gender-matched controls (n=13) had repeated measurements of TDEE by FHRM, REE, and maximal cardiopulmonary exercise testing (CPET) during a 6-week exercise and diet program. RESULTS: While the mean REE was similar in both groups, ECA was significantly lower in CF adolescents as compared to controls (p=0.02). During CPET, maximal exercise in CF was characterized by hyperventilation, which was unrelated to ventilation-perfusion mismatching. There were no changes in REE after dietary intervention. CONCLUSION: ECA in CF adolescents with normal lung function is lower when compared to healthy controls. These findings support the hypothesis that clinically stable patients with CF have inefficient energy metabolism or alternatively conserve energy during activities of daily living.  相似文献   
53.
Summary: A female patient with isovaleric acidaemia had a successful outcome from pregnancy.  相似文献   
54.
55.
56.
57.
58.
AIM: Cardiovascular risk factors can be present in children and young adults. We previously found abnormal microvascular function in children who had glucose intolerance and insulin resistance. The aim of the present study was to investigate whether they also have abnormalities in left ventricular mass (LVM) and arterial stiffness. METHODS: We measured heart dimensions and LVM using echocardiography, and arterial stiffness using pulse wave analysis in 23 children with good glucose handling (postfeeding glucose: 3.9 to 5 mmol/L) and 21 with poor glucose handling (7.7 to 11.4 mmol/L). RESULTS: The time to pulse reflection was slightly shorter in the poorer glucose handlers (mean+/-SD: 143+/-10 vs 153+/-20 ms, P=0.04), suggestive of increased arterial stiffness. Also in this group, there were significant relationships between intraventricular septal thickness, blood pressure and body mass index, but not in the normal glucose handlers. CONCLUSIONS: We have found that normal children who are in the lowest quintile of glucose tolerance in comparison with their peers are exhibiting the first signs of arterial stiffening. In addition, we have seen the beginnings of a relationship between blood pressure, body mass index and left ventricular enlargement in this group. While these changes may not yet be clinically significant, their emergence might be further evidence of early predisposition to cardiovascular disease.  相似文献   
59.
AIM: To evaluate whether the introduction of a strict protocol approach based on the systemic evaluation of critically ill pregnant women with complications of abortion affected outcome. SETTING: Indigent South Africans managed in the regional and tertiary hospitals of the Pretoria Academic Complex. METHOD: Since 1997 a standard definition of severe acute maternal morbidity (SAMM) has been used in the Pretoria Academic Complex. All cases of SAMM and maternal deaths were entered on the Maternal Morbidity and Mortality Audit System programme. A comparison of outcome of severely ill women who had complications of abortion was made between 1997-1998 (original protocol) and 2002-2004 (strict protocol). OUTCOME MEASURES: The mortality index and prevalence of organ system failure or dysfunction. RESULTS: In 1997-1998 there were 43 women with SAMM who survived and a further 10 maternal deaths due to complications of abortion, compared with 107 women with SAMM and 7 maternal deaths during 2002-2004. The mortality index declined from 18.9% in 1997-1998 to 6.1% in 2002-2004 (p = 0.02, odds ratio 0.28, 95% confidence limits 0.10 - 0.79). Significantly more women had hypovolaemic shock in 2002-2004 compared with 1997-1998 (54.4% v. 35.8%, p = 0.04), but fewer women had immune system failure including septic shock (18.4% v. 47.2%, p = 0.0002) and metabolic dysfunction (0 v. 5.7%, p = 0.03) and there was a trend to less renal failure (10.5% v. 22.6%, p = 0.06) and cardiac failure (4.4% v. 13.2%, p = 0.08). CONCLUSION: The strict protocol approach based on systemic evaluation in managing critically ill pregnant women with complications of abortion, coupled with an intensive, regular feedback mechanism, has been associated with a reduction in the mortality index.  相似文献   
60.
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