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   3395410篇
  免费   252767篇
  国内免费   5052篇
耳鼻咽喉   47356篇
儿科学   111310篇
妇产科学   94105篇
基础医学   493009篇
口腔科学   97615篇
临床医学   306764篇
内科学   651286篇
皮肤病学   74391篇
神经病学   270948篇
特种医学   129426篇
外国民族医学   902篇
外科学   510042篇
综合类   76573篇
现状与发展   13篇
一般理论   1305篇
预防医学   268439篇
眼科学   79469篇
药学   254508篇
  13篇
中国医学   6422篇
肿瘤学   179333篇
  2018年   36166篇
  2017年   27515篇
  2016年   30849篇
  2015年   35084篇
  2014年   49216篇
  2013年   74507篇
  2012年   101864篇
  2011年   108199篇
  2010年   64226篇
  2009年   60884篇
  2008年   101973篇
  2007年   108352篇
  2006年   109450篇
  2005年   106456篇
  2004年   102933篇
  2003年   98572篇
  2002年   96157篇
  2001年   151316篇
  2000年   156065篇
  1999年   131965篇
  1998年   38392篇
  1997年   34031篇
  1996年   34014篇
  1995年   32533篇
  1994年   30227篇
  1993年   28540篇
  1992年   105602篇
  1991年   103234篇
  1990年   100861篇
  1989年   97449篇
  1988年   90227篇
  1987年   88566篇
  1986年   83758篇
  1985年   80658篇
  1984年   60486篇
  1983年   51880篇
  1982年   30806篇
  1981年   27764篇
  1979年   56846篇
  1978年   40240篇
  1977年   33760篇
  1976年   32169篇
  1975年   34403篇
  1974年   41626篇
  1973年   39804篇
  1972年   37146篇
  1971年   35088篇
  1970年   32357篇
  1969年   30750篇
  1968年   28113篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Severe tuberculosis (TB) requiring intensive care unit (ICU) care is rare but commonly known to be of markedly bad prognosis. The present study aimed to describe this condition and to determine the mortality rate and risk factors associated with mortality. Patients with confirmed TB admitted to ICU between 1990 and 2001 were retrospectively identified and enrolled. Clinical, radiological and bacteriological data at admission and during hospital stay were recorded. A multivariate analysis was performed to identify the predictive factors for mortality. A total of 58 TB patients (12 females, mean age 48 yrs) admitted to ICU were included. Mean Acute Physiology and Chronic Health Evaluation (APACHE) II score at admission was 13.1+/-5.6 and 22 of 58 (37.9%) patients required mechanical ventilation. The in-hospital mortality was 15 of 58 (25.9%); 13 (22.4%) patients died in the ICU. The mean survival of patients who died was 53.6 days (range 1-229), with 50% of the patients dying within the first 32 days. The factors independently associated with mortality were: acute renal failure, need for mechanical ventilation, chronic pancreatitis, sepsis, acute respiratory distress syndrome, and nosocomial pneumonia. These data indicate a high mortality of patients with tuberculosis requiring intensive care unit care and identifies new independently associated risk factors.  相似文献   
42.
43.
44.
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   
45.
46.
47.
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   
48.
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   
49.
50.
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