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   2274225篇
  免费   171595篇
  国内免费   3676篇
耳鼻咽喉   33508篇
儿科学   77673篇
妇产科学   65206篇
基础医学   328458篇
口腔科学   63384篇
临床医学   197791篇
内科学   446446篇
皮肤病学   48979篇
神经病学   177691篇
特种医学   90001篇
外国民族医学   973篇
外科学   350654篇
综合类   49068篇
现状与发展   1篇
一般理论   632篇
预防医学   170860篇
眼科学   51922篇
药学   171370篇
  3篇
中国医学   4406篇
肿瘤学   120470篇
  2018年   22323篇
  2016年   18831篇
  2015年   21445篇
  2014年   29829篇
  2013年   45637篇
  2012年   62516篇
  2011年   66671篇
  2010年   39718篇
  2009年   37662篇
  2008年   64153篇
  2007年   69207篇
  2006年   69878篇
  2005年   68268篇
  2004年   66341篇
  2003年   64196篇
  2002年   63133篇
  2001年   105758篇
  2000年   109217篇
  1999年   92953篇
  1998年   26151篇
  1997年   23500篇
  1996年   23879篇
  1995年   22643篇
  1994年   21434篇
  1993年   19864篇
  1992年   74445篇
  1991年   73141篇
  1990年   71733篇
  1989年   68999篇
  1988年   64021篇
  1987年   62915篇
  1986年   59284篇
  1985年   56801篇
  1984年   42685篇
  1983年   36389篇
  1982年   21558篇
  1981年   19342篇
  1980年   17746篇
  1979年   39329篇
  1978年   27500篇
  1977年   23641篇
  1976年   22265篇
  1975年   24258篇
  1974年   28498篇
  1973年   27454篇
  1972年   25783篇
  1971年   23733篇
  1970年   22269篇
  1969年   20860篇
  1968年   19381篇
排序方式: 共有10000条查询结果,搜索用时 313 毫秒
31.
32.
33.

Objective

To examine whether a healthy weight intervention embedded in the Parents as Teachers (PAT) home visiting program, which was previously found to improve mothers’ body mass index (BMI) and obesity-related behaviors, changed the BMI of preschool children or maternal feeding practices.

Methods

This stratified randomized trial included preschool-aged children at risk for overweight whose mothers were overweight or had obesity (n?=?179). The Healthy Eating and Active Living Taught at Home (HEALTH) intervention was based on the Diabetes Prevention Program. Differences were examined using repeated-measures mixed-ANOVA models.

Results

Compared with PAT usual care, the HEALTH intervention had no effect on children's BMI or maternal feeding practices. However, combined analyses showed that children's BMI percentile decreased (P??=?.007), BMI z-scores were maintained (P??=?.19), and 3 of 8 feeding practices improved over time (P < .05).

Conclusions and Implications

Additional research is needed to assess the effectiveness of PAT to prevent preschool-age obesity using rigorous designs (eg, group-randomized trials) and to identify its active components. HEALTH is ready to be scaled up to prevent maternal weight gain through embedding within the national PAT program.  相似文献   
34.
35.

Background and objectives

A prompt and effective management of trauma patient is necessary. The aim of this case report is to highlight the importance of intraoperative echocardiography as a useful tool in patients suffering from refractory hemodynamic instability no otherwise explained.

Case report

A 41 year‐old woman suffered a car accident. At the emergency department, no abnormalities were found in ECG or chest X‐ray. Abdominal ultrasound revealed the presence of abdominal free liquid and the patient was submitted to urgent exploratory laparotomy. Nevertheless, she persisted suffering arterial hypotension and metabolic acidosis. Looking for the reason of her hemodynamic instability, intraoperative transthoracic echocardiography was performed, finding out the presence of pericardial effusion. Once the cardiac surgeon extracted pericardial clots, patient's situation improved clinically and analytically.

Conclusion

Every anesthesiologist should be able to use the intraoperative echocardiography as an effective tool in order to establish the appropriate measures to promote the survival of patients suffering severe trauma.  相似文献   
36.
37.

Objective

Comparative survival between neoadjuvant chemotherapy and adjuvant chemotherapy for patients with cT2-4N0-1M0 non–small cell lung cancer has not been extensively studied.

Methods

Patients with cT2-4N0-1M0 non–small cell lung cancer who received platinum-based chemotherapy were retrospectively identified. Exclusion criteria included stage IV disease, induction radiotherapy, and targeted therapy. The primary end point was disease-free survival. Secondary end points were overall survival, chemotherapy tolerance, and ability of Response Evaluation Criteria In Solid Tumors response to predict survival. Survival was estimated using the Kaplan–Meier method, compared using the log-rank test and Cox proportional hazards models, and stratified using matched pairs after propensity score matching.

Results

In total, 330 patients met the inclusion criteria (n = 92/group after propensity-score matching; median follow-up, 42 months). Five-year disease-free survival was 49% (95% confidence interval, 39-61) for neoadjuvant chemotherapy versus 48% (95% confidence interval, 38-61) for adjuvant chemotherapy (P = .70). On multivariable analysis, disease-free survival was not associated with neoadjuvant chemotherapy or adjuvant chemotherapy (hazard ratio, 1.1; 95% confidence interval, 0.64-1.90; P = .737), nor was overall survival (hazard ratio, 1.21; 95% confidence interval, 0.63-2.30; P = .572). The neoadjuvant chemotherapy group was more likely to receive full doses and cycles of chemotherapy (P = .014/0.005) and had fewer grade 3 or greater toxicities (P = .001). Response Evaluation Criteria In Solid Tumors response to neoadjuvant chemotherapy was associated with disease-free survival (P = .035); 15% of patients receiving neoadjuvant chemotherapy (14/92) had a major pathologic response.

Conclusions

Timing of chemotherapy, before or after surgery, is not associated with an improvement in overall or disease-free survival among patients with cT2-4N0-1M0 non–small cell lung cancer who undergo complete surgical resection.  相似文献   
38.
39.
40.
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