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   1339800篇
  免费   94667篇
  国内免费   2926篇
耳鼻咽喉   19726篇
儿科学   40291篇
妇产科学   38685篇
基础医学   187730篇
口腔科学   39911篇
临床医学   112945篇
内科学   263562篇
皮肤病学   30378篇
神经病学   106589篇
特种医学   53827篇
外国民族医学   435篇
外科学   208808篇
综合类   31069篇
现状与发展   6篇
一般理论   436篇
预防医学   92222篇
眼科学   31394篇
药学   100360篇
  4篇
中国医学   2990篇
肿瘤学   76025篇
  2018年   11816篇
  2015年   11968篇
  2014年   16800篇
  2013年   25385篇
  2012年   33221篇
  2011年   35111篇
  2010年   20874篇
  2009年   20357篇
  2008年   33787篇
  2007年   36928篇
  2006年   37489篇
  2005年   36219篇
  2004年   35310篇
  2003年   34248篇
  2002年   33781篇
  2001年   63729篇
  2000年   65424篇
  1999年   55495篇
  1998年   14694篇
  1997年   13486篇
  1996年   12970篇
  1995年   12246篇
  1994年   11493篇
  1992年   42842篇
  1991年   41347篇
  1990年   40627篇
  1989年   39609篇
  1988年   37018篇
  1987年   36448篇
  1986年   34926篇
  1985年   33135篇
  1984年   24841篇
  1983年   21071篇
  1982年   12674篇
  1981年   11578篇
  1980年   10784篇
  1979年   23947篇
  1978年   17082篇
  1977年   14849篇
  1976年   13391篇
  1975年   15281篇
  1974年   18092篇
  1973年   17579篇
  1972年   16824篇
  1971年   15736篇
  1970年   14930篇
  1969年   14362篇
  1968年   13472篇
  1967年   12024篇
  1966年   11267篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
102.
103.
Monatsschrift Kinderheilkunde - Fusionen und Übernahmen in der Pharmaindustrie haben zu einer Konzentration geführt, von der auch die Impfstoffproduktion mit nur noch wenigen global...  相似文献   
104.
Abstract

The leading cause of death of adolescents in developed countries is injury. Alcohol is a major contributor to adolescent injury. Most of the injury deaths in youth are caused by traffic crashes. Driving under the influence (DUI) and riding with a driver who is under the influence (RUI) of alcohol increase the risk of road crash. The focus of this study is how adolescents’ risk of DUI and RUI differ in relation to their experience of parental control and peer pressure to substance use, other risky behaviours and leisure time activities. The analyses are based on data from the European School Survey Project on Alcohol and Other Drugs collected from 15- to 16-year-old Finnish adolescents in 2015 (n?=?4049, response rate 88.7%). The study shows that problems tend to entangle in some adolescent groups in which DUI and RUI are also more common. Adolescents with higher probability of using various substances, of starting alcohol use at young age, of experiencing weak parental control, and high peer pressure are at higher risk of DUI and RUI. The results indicate that professionals and authorities handling underage DUI and RUI ought to consider adolescents’ situation as a whole.  相似文献   
105.
Postoperative pulmonary complications are associated with an increase in mortality, morbidity and healthcare utilisation. The Agency for Healthcare Research and Quality recommends risk assessment for postoperative respiratory complications in patients undergoing surgery. In this hospital registry study of adult patients undergoing non-cardiac surgery between 2005 and 2017 at two independent healthcare networks, a prediction instrument for early postoperative tracheal re-intubation was developed and externally validated. This was based on the development of the Score for Prediction Of Postoperative Respiratory Complications. For predictor selection, stepwise backward logistic regression and bootstrap resampling were applied. Development and validation cohorts were represented by 90,893 patients at Partners Healthcare and 67,046 patients at Beth Israel Deaconess Medical Center, of whom 699 (0.8%) and 587 (0.9%) patients, respectively, had their tracheas re-intubated. In addition to five pre-operative predictors identified in the Score for Prediction Of Postoperative Respiratory Complications, the final model included seven additional intra-operative predictors: early post-tracheal intubation desaturation; prolonged duration of surgery; high fraction of inspired oxygen; high vasopressor dose; blood transfusion; the absence of volatile anaesthetic use; and the absence of lung-protective ventilation. The area under the receiver operating characteristic curve for the new score was significantly greater than that of the original Score for Prediction Of Postoperative Respiratory Complications (0.84 [95%CI 0.82–0.85] vs. 0.76 [95%CI 0.75–0.78], respectively; p < 0.001). This may allow clinicians to develop and implement strategies to decrease the risk of early postoperative tracheal re-intubation.  相似文献   
106.
107.
Objective: A multidisciplinary vocational rehabilitation programme, the Vocational Enablement Protocol (VEP) was developed to address the specific needs of employees with hearing difficulties. In the current study we evaluated the process of implementing the VEP in audiologic care among employees with hearing impairment. Design: In conjunction with a randomized controlled trial, we collected and analysed data on seven process parameters: recruitment, reach, fidelity, dose delivered, dose received and implemented, satisfaction, and perceived benefit. Study sample: Sixty-six employees with hearing impairment participated in the VEP. The multidisciplinary team providing the VEP comprised six professionals. Results: The professionals performed the VEP according to the protocol. Of the recommendations delivered by the professionals, 31% were perceived as implemented by the employees. Compliance rate was highest for hearing-aid uptake (51%). Both employees and professionals were highly satisfied with the VEP. Participants rated good perceived benefit from it. Conclusions: Our results indicate that the VEP could be a useful treatment for employees with hearing difficulties from a process evaluation perspective. Implementation research in the audiological setting should be encouraged in order to further provide insight into parameters facilitating or hindering successful implementation of an intervention and to improve its quality and efficacy.  相似文献   
108.
109.
We prospectively evaluated the effectiveness of contrast-enhanced ultrasonography (CEUS) for differentiation of benign versus malignant portal vein thrombosis (PVT). We studied a total of 43 patients with chronic liver disease, hepatocellular carcinoma-suggestive nodules and confirmed PVT, in whom the nature of the PVT was confirmed by follow-up imaging (US, computed tomography and/or magnetic resonance imaging) performed up to 6 mo after CEUS. PVT was assessed by US, Doppler US and CEUS with respect to vessel wall disruption and/or invasion, color Doppler vascularization, pulsed Doppler vascularization pattern and CEUS enhancement and vascularization pattern, and thrombi were classified as benign or malignant based on these findings. Follow-up studies revealed malignant PVT in 22 of the 43 patients (51%) and benign PVT in 21 patients (49%). CEUS findings were consistent with follow-up studies in 41 of the 43 patients (95%), with κ?=?0.903 (p < 0.0001), sensitivity?=?91% and specificity?=?100%, indicating that CEUS can be confidently used to differentiate benign from malignant portal vein thrombosis in the setting of chronic liver disease.  相似文献   
110.

Background and aims

It is not known whether non alcoholic fatty liver disease (NAFLD) is a risk factor for diabetes in non obese, non centrally-obese subjects. Our aim was to investigate relationships between fatty liver, insulin resistance and a biomarker score for liver fibrosis with incident diabetes at follow up, in subjects who were neither obese nor centrally-obese.

Methods and results

As many as 70,303 subjects with a body mass index (BMI) < 25 kg/m2 and without diabetes were followed up for a maximum of 7.9 years. At baseline, fatty liver was identified by liver ultrasound, insulin resistance (IR) by homeostatic model assessment of insulin resistance (HOMA-IR) ≥2.0, and central obesity by waist circumference (waist circumference ≥90 cm (men) and ≥85 cm (women). The Fibrosis-4 (FIB-4 score) was used to estimate extent of liver fibrosis. Cox proportional hazards models adjusted for confounders were used to estimate hazard ratios (aHRs) for incident diabetes. As many as 852 incident cases of diabetes occurred during follow up (median [IQR] 3.71 [2.03] years). Mean ± SD BMI was 22.8 ± 1.8 and 21.7 ± 2.0 kg/m2 in subjects with and without diabetes at follow up. In subjects without central obesity and with fatty liver, aHRs (95% CI) for incident diabetes at follow up were 2.17 (1.56, 3.03) for men, and 2.86 (1.50,5.46) for women. Similar aHRs for incident diabetes occurred with fatty liver, IR and the highest quartile of FIB-4 combined, in men; and there was a non significant trend toward increased risk in women.

Conclusions

In normal weight, non-centrally obese subjects NAFLD is an independent risk factor for incident diabetes.  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