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   26907篇
  免费   2821篇
  国内免费   321篇
耳鼻咽喉   113篇
儿科学   94篇
妇产科学   938篇
基础医学   1248篇
口腔科学   529篇
临床医学   4638篇
内科学   5111篇
皮肤病学   203篇
神经病学   1667篇
特种医学   467篇
外国民族医学   6篇
外科学   2226篇
综合类   3365篇
现状与发展   3篇
一般理论   2篇
预防医学   5600篇
眼科学   81篇
药学   1891篇
  44篇
中国医学   478篇
肿瘤学   1345篇
  2024年   53篇
  2023年   489篇
  2022年   728篇
  2021年   1295篇
  2020年   1284篇
  2019年   1056篇
  2018年   1096篇
  2017年   1213篇
  2016年   1324篇
  2015年   1089篇
  2014年   1926篇
  2013年   2838篇
  2012年   1732篇
  2011年   1729篇
  2010年   1381篇
  2009年   1313篇
  2008年   1272篇
  2007年   1121篇
  2006年   963篇
  2005年   902篇
  2004年   764篇
  2003年   637篇
  2002年   580篇
  2001年   515篇
  2000年   398篇
  1999年   302篇
  1998年   327篇
  1997年   285篇
  1996年   224篇
  1995年   170篇
  1994年   158篇
  1993年   133篇
  1992年   132篇
  1991年   112篇
  1990年   81篇
  1989年   59篇
  1988年   69篇
  1987年   66篇
  1986年   37篇
  1985年   45篇
  1984年   38篇
  1983年   25篇
  1982年   16篇
  1981年   14篇
  1980年   11篇
  1979年   11篇
  1978年   8篇
  1977年   11篇
  1976年   9篇
  1975年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Background and Objectives The benefits and indications for blood transfusion among surgical patients are controversial. There is evidence which suggests that blood transfusion is associated with poor clinical outcomes and risks of infection, but there are few data in the elderly population. Materials and Methods Data were collected on haemoglobin concentrations and transfusions in 919 patients undergoing hip fracture repair at a university hospital over a 2‐year period. 28‐day and 180‐day mortality were specified as primary outcomes. A composite infection outcome (chest infections, urinary tract infections and wound infections) was the main secondary outcome. Preoperative, operative and/or postoperative transfusions were the main exposure variable. Regression analyses were used to explore the associations between transfusion and outcomes, adjusting for pre‐defined preoperative variables. Results 300 patients (32·6%) were transfused at least once during their admission. There was no evidence of a significant difference in either 28‐day survival or 180‐day survival between transfused and non‐transfused hip fracture patients. The transfused group had higher adjusted composite infection rate (HR, 1·91; 95% CI, 1·41–2·59, P < 0·001) and prolonged length of stay in hospital than the non‐transfused group (HR, 1·15; 95% CI, 1·07, 1·23, P < 0·001). Anaemia at the time of admission, extra capsular fracture and using walking aids in an indoor setting were preoperative variables, which predicted the need for transfusion. Conclusion Among an elderly population with hip fracture, blood transfusion was not associated with changes in mortality, but was associated with an increased rate of postoperative infection. These data add to the wider literature about adverse clinical outcomes in patients receiving blood transfusions and emphasises the need for prospective trials to evaluate the role of transfusion in the elderly.  相似文献   
992.
Strontium ranelate is claimed to be related with increased risk of thromboembolic events. No explanation of this increased incidence of thromboembolism has been identified. However, growing evidence has clearly demonstrated the involvement of blood rheology in any thrombotic process. The aim of this study was to assess hemorheological changes with strontium ranelate treatment in elderly women with osteoporosis. This study was designed in a prospective manner. Twenty-two elderly women diagnosed with osteoporosis were included. During a 2-month treatment period, participants received strontium ranelate 2 g/day. Hemorheological parameters including erythrocyte deformability, erythrocyte aggregation and plasma viscosity were measured before and after 2 months therapy with strontium ranelate. The median age of the patients was 70.0 (range = 65-80) years. After 60 days of treatment, there was no statistically significant change in hemorheological parameters. None of the subjects developed clinical venous thromboembolic event (VTE) during the 2-month period of strontium ranelate treatment. Our study demonstrated that in elderly women, treatment of osteoporosis with strontium ranelate did not change hemorheological parameters over 2 months of time. However, its long-term effects on hemorheologic parameters should be evaluated further with a larger sample.  相似文献   
993.
The determination of the approximately truest value in height measurement is important in many fields, but it is difficult to perform true measurements, especially in the elderly individuals. We planned to investigate the following items in geriatric Turkish population: to calculate the decrease in height with advancing age by using the standing height measurement and estimated height derived from the knee height; to evaluate the significance of difference between the two measurement methods in the calculation of body mass index (BMI) and waist/height ratio (WHtR); to determine the cut-off value of WHtR according to estimated height in elderly individuals. We studied 551 cases aged between 19 and 97 years. Knee height was measured using a sliding caliper in a sitting position. Linear regression analysis was carried out to derive predictive equations for the estimation of stature with adults (≤50 years of age) according to the gender. This equation was then used to estimate height among elderly subjects. Of the cases, 60.3% were <60 years (mean: 48.75 ± 7.50); 39.7% of the cases were >60 years (mean: 69.51 ± 7.12). Estimated BMI (EBMI) measurements in the females and males >60 years were in average 1.23 kg/m2 and 0.92 kg/m2 higher than their real BMIs, respectively. EBMI measurements in the females <60 years were 0.32 kg/m2 higher than their real BMIs (p < 0.01). There is a statistically significant difference between WHtR in the females of both age groups, and in the males >60 years, as compared to our estimated WHtR (EWHtR) measurements (p < 0.01). The cut-off point of WHtR was 0.61 and 0.58 in the female and male cases of >60 years in our study, respectively. WHtR seemed to be a better anthropometric index that could predict most cardiometabolic risk factors in our study. EWHtR emerged to be a better cardiometabolic risk index especially in the elderly group.  相似文献   
994.
Although an association between SA concentrations and mortality in the patients is well known, this association is not conclusive in elderly community-dwelling populations. We therefore attempted to determine whether this association could be extended to a Japanese 70-year-old community-dwelling population. Seventy-year-old subjects residing in Niigata City, Japan participated. Baseline examinations including a determination of SA concentrations were performed in June 1998 in 600 participants, and they were followed for 10 years. During the 10-year follow up, 80 subjects died. Albumin levels were divided into four groups (highest > 45 g/l, higher 43-44 g/l, lower 41-42 g/l, lowest <40 g/l). The survival rate using Kaplan-Meier methods was longer in the highest and higher albumin groups than in the lowest and lower groups. No differences were found between the four groups in the mortalities from cancer, cardiovascular disease (CVD) or pneumonia. Individuals with the lowest albumin levels had 2.7 or 2.9 times higher total mortality, whether adjusted with confounding factors or not, using Cox regression analysis. The mortality hazard ratio (HR) found in the lowest group was compared to the highest group. In an elderly 70-year-old Japanese community-dwelling population, lower SA concentrations were an independent predictor of total mortality, but not mortality due to cancer, CVD, or pneumonia.  相似文献   
995.
996.
997.
998.
999.
1000.
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