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   2339篇
  免费   6篇
  国内免费   2篇
耳鼻咽喉   7篇
儿科学   157篇
妇产科学   24篇
基础医学   157篇
口腔科学   12篇
临床医学   208篇
内科学   837篇
皮肤病学   82篇
神经病学   168篇
特种医学   51篇
外科学   324篇
综合类   12篇
预防医学   159篇
眼科学   69篇
药学   39篇
中国医学   5篇
肿瘤学   36篇
  2023年   6篇
  2022年   10篇
  2021年   24篇
  2020年   9篇
  2019年   336篇
  2018年   370篇
  2017年   164篇
  2016年   24篇
  2015年   60篇
  2014年   281篇
  2013年   125篇
  2012年   71篇
  2011年   141篇
  2010年   96篇
  2009年   108篇
  2008年   129篇
  2007年   125篇
  2006年   34篇
  2005年   54篇
  2004年   13篇
  2003年   20篇
  2002年   4篇
  2001年   4篇
  2000年   2篇
  1999年   7篇
  1998年   7篇
  1997年   1篇
  1996年   2篇
  1994年   1篇
  1993年   2篇
  1991年   1篇
  1989年   1篇
  1986年   1篇
  1985年   15篇
  1984年   23篇
  1983年   17篇
  1982年   7篇
  1981年   5篇
  1980年   9篇
  1979年   13篇
  1978年   6篇
  1977年   6篇
  1976年   5篇
  1975年   1篇
  1974年   3篇
  1971年   2篇
  1970年   1篇
  1969年   1篇
排序方式: 共有2347条查询结果,搜索用时 31 毫秒
1.

Objectives

Expedient extubation after cardiac surgery has been associated with improved outcomes, leading to postoperative extubation frequently during overnight hours. However, recent evidence in a mixed medical-surgical intensive care unit population demonstrated worse outcomes with overnight extubation. This study investigated the impact of overnight extubation in a statewide, multicenter Society of Thoracic Surgeons database.

Methods

Records from 39,812 patients undergoing coronary artery bypass grafting or valve operations (2008-2016) and extubated within 24 hours were stratified according to extubation time between 06:00 and 18:00 (day) or between 18:00 and 6:00 (overnight). Outcomes including reintubation, mortality, and composite morbidity-mortality were evaluated using hierarchical regression models adjusted for Society of Thoracic Surgeons predictive risk scores. To further analyze extubation during the night, a subanalysis stratified patients into 3 groups: 06:00 to 18:00, 18:00 to 24:00, and 24:00 to 06:00.

Results

A total of 20,758 patients were extubated overnight (52.1%) and were slightly older (median age 66 vs 65 years, P < .001) with a longer duration of ventilation (4 vs 7 hours, P < .001). Day and overnight extubation were associated with equivalent operative mortality (1.7% vs 1.7%, P = .880), reintubation (3.7% vs 3.4%, P = .141), and composite morbidity-mortality (8.2% vs 8.0%, P = .314). After risk adjustment, overnight extubation was not associated with any difference in reintubation, mortality, or composite morbidity-mortality. On subanalysis, those extubated between 24:00 and 06:00 exhibited increased composite morbidity-mortality (odds ratio, 1.18; P = .001) but no difference in reintubation or mortality.

Conclusions

Extubation overnight was not associated with increased mortality or reintubation. These results suggest that in the appropriate clinical setting, it is safe to routinely extubate cardiac surgery patients overnight.  相似文献   
2.
3.
The prediction from Sokolov's (1960) theory that, following OR habituation, size of OR return is proportional to the amount of difference between the new stimulus and the habituating stimulus was tested using an auditory stimulus varying in frequency and intensity. Five Ss were allocated to each of 16 conditions, three conditions involving changes in frequency, three involving changes in intensity, nine involving changes in both frequency and intensity, with one control condition involving a repetition of the habituating stimulus. Following habituation of the GSR component of the OR to a criterion of response failure for three successive trials, magnitude of GSR under the 16 conditions was measured. Contrary to Sokolov's theory, only increase in intensity had a significantly different effect on OR return. More importantly, it was found that Ss habituating rapidly to the initial stimulus were less likely to show OR return to stimulus change. It was concluded that individual differences in habituation rate may be more important than stimulus difference effects in selective habituation.  相似文献   
4.
5.
6.
目的:从细胞水平探讨LPK-26对κ受体的作用及分子机制。方法:通过[3H]-Dip和[35S]GTPγS放射性结合实验研究LPK-26对CHO细胞上稳定表达κ阿片受体的竞争性受体结合特征及LPK-26对κ阿片受体偶联的G蛋白的激活。结果:LPK-26是一种κ阿片受体激动剂,其Ki值是0.66 nmol.L-1,与U50,488H相似;并且通过[35S]GTPγS结合实验,LPK-26激活G蛋白的能力明显大于U50,488H。结论:LPK-26可能是一种较为理想的新型镇痛药物。  相似文献   
7.
ObjectiveThere is a little published data on prevalence and determinants of underweight, overweight and obesity among adults in Nepal. This study analysed the cross-sectional Nepal Demographic and Health Survey (NDHS) 2016 to obtain these using the World Health Organization (WHO) and Asian-specific cutoffs of body mass index (BMI).MethodsThe 2016 NDHS used a multistage cluster-sampling design to obtain data on major health indicators in Nepal. The BMI cutoffs for underweight was <18.5 kg/m2. The BMI cutoffs for overweight/obesity as per the Asian and WHO classifications were ≥23, and ≥25 kg/m2, respectively. After reporting the prevalence according to sex and background characteristics, multilevel logistic regression was conducted to estimate odds ratios.SubjectsThis analysis included 12,652 adults (5283 males and 7369 females) with a median age of 40 years (interquartile range [IQR]: 28–54).ResultsThe overall median BMI was 21.5 kg/m2 (IQR:19.3–24.3). The overall prevalence of underweight was 16.7% (15.1% among males and 17.1% among females). The Asian-specific BMI cutoffs found the prevalence of overweight and obesity as 26.4% (27.4% among males and 25.6% among females) and 11.0% (7.7% among males and 13.3% among females), respectively. The WHO-recommended BMI cutoffs found 18.2% people overweight (16.7% among males and 19.3% among females) and 4.3% (2.5% among males and 5.6% among females) people obese. The prevalence and odds of extreme body weight categories (i.e., underweight, overweight and obesity) varied according to age, sex, education level, household wealth status, place, ecological zone and provinces of residence as per both recommended cutoffs. Overall, higher education level and wealth status were positively associated with overweight/obesity and inversely associated with underweight as per both cutoffs.ConclusionA large proportion Nepalese adults have either underweight, overweight or obesity, and could be at a greater risk of mortality and morbidity due to these extreme body weight categories. It is essential to address the factors or characteristics that are associated with the higher prevalence and likelihood of these extreme body weight categories to reduce the overall burden of underweight and overweight/obesity in Nepal.  相似文献   
8.
The aim of this retrospective, single-centre study was to identify the risk factors for bleeding after dental extractions in patients aged over 60 who were being treated with antiplatelet drugs. A total of 338 patients who fulfilled the inclusion criteria were enrolled, and their personal and clinical details, and complications with bleeding after extraction, were retrieved and recorded. There were 182 men and 156 women (mean (SD) age 72 (8) years). A total of 469 teeth were extracted, with a mean (SD) of 1.4 (0.6) teeth/patient. Seventy-seven patients (23%) developed mild, and 55 (16%) severe, bleeding postoperatively. No patient developed a major cardiovascular or cerebrovascular event. We calculated the significance of the association of different variables with the occurrence of postoperative haemorrhage using a multivariate stepwise logistic regression model. The presence of three or more coexisting conditions, a complicated tooth extraction, and the use of two antiplatelet drugs were independent risk factors, while discontinuation of antiplatelet treatment four or more days before the tooth was extracted was a protective factor. This suggests that clinicians should assess the thrombotic risk associated with the interruption of antiplatelet drugs as well as the risk of bleeding for each patient before dental extraction. Strong and effective measures for haemostasis may be preferred over blind discontinuation of antiplatelet drugs. This study is registered in the Chinese Clinical Trial Registry (No. ChiCTR1800014355).  相似文献   
9.

Background and aims

There is controversy on the potentially benign nature of metabolically healthy obesity (MHO), i.e., obese persons with few or no metabolic abnormalities. So far, associations between MHO and coronary artery calcification (CAC), a measure of subclinical atherosclerosis, have mainly been studied cross-sectionally in Asian populations. We assessed cross-sectional and longitudinal MHO CAC associations in a Caucasian population.

Methods and results

In the Heinz Nixdorf Recall Study, a population-based cohort study in Germany, CAC was assessed by electron-beam tomography at baseline and at 5-year follow-up. For cross-sectional and longitudinal analyses, we included 1585 participants free of coronary heart disease at baseline, with CAC measurements at baseline and at follow-up, and with either normal weight (BMI 18.5–24.9 kg/m2) or obesity (BMI ≥30.0 kg/m2) at baseline. We used four definitions of MHO. In our main analysis, we defined obese persons as metabolically healthy if they met ≤1 of the NCEP ATP III criteria for the definition of the metabolic syndrome – waist circumference was not taken into account because of collinearity with BMI.Persons with MHO had a higher prevalence of CAC than metabolically healthy normal weight (MHNW) persons (prevalence ratio = 1.59 (95% confidence interval 1.38–1.84) for the main analysis). Persons with MHO had slightly larger odds of CAC progression than persons with MHNW (odds ratios ranged from 1.17 (0.69–1.99) to 1.48 (1.02–2.13) depending on MHO definition and statistical approach).

Conclusion

Our analyses on MHO CAC associations add to the evidence that MHO is not a purely benign health condition.  相似文献   
10.

Objective

Although the Ross procedure provides excellent long-term survival and a high quality of life, its use has been limited to relatively few centers. In this study, we evaluated long-term Ross procedure results in adults to assess the predictors of pulmonary autograft durability.

Methods

Between 1998 and 2015, 793 consecutive adult patients underwent the Ross procedure. The total root replacement technique was used in all patients.

Results

The early mortality rate was 2.9%. The mean follow-up duration was 6.5 ± 3.2 years, and the 10-year survival rate was 90.4%. Longitudinal mixed-effects ordinal regression identified a combination of bicuspid aortic valve and aortic insufficiency (odds ratio, 2.19; P < .001) as predictors for progression of autograft valve insufficiency at follow-up. The cumulative incidence of autograft reoperations at 10 years was 8.6%. Competing risk regression identified bicuspid aortic valve insufficiency as the independent predictor of autograft reoperation (subdistribution hazard ratio, 2.16; P = .030). Moreover, patients with bicuspid aortic valve and aortic insufficiency had greater increases in annulus (P < .001), sinus (P < .001), and ascending aorta (P < .001) diameters over time.

Conclusions

For patients undergoing the Ross procedure, a combination of bicuspid aortic valves and aortic insufficiency is the main risk factor for late autograft dilatation and dysfunction.  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