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   1679851篇
  免费   120782篇
  国内免费   2529篇
耳鼻咽喉   23972篇
儿科学   55749篇
妇产科学   48699篇
基础医学   252272篇
口腔科学   47661篇
临床医学   143115篇
内科学   323819篇
皮肤病学   36427篇
神经病学   128284篇
特种医学   64648篇
外国民族医学   426篇
外科学   258284篇
综合类   33654篇
现状与发展   1篇
一般理论   407篇
预防医学   123889篇
眼科学   39104篇
药学   129230篇
  1篇
中国医学   3238篇
肿瘤学   90282篇
  2018年   15626篇
  2015年   15133篇
  2014年   20875篇
  2013年   31984篇
  2012年   43749篇
  2011年   47209篇
  2010年   27804篇
  2009年   26233篇
  2008年   45665篇
  2007年   49435篇
  2006年   50232篇
  2005年   49055篇
  2004年   47358篇
  2003年   45841篇
  2002年   45265篇
  2001年   76456篇
  2000年   78781篇
  1999年   66469篇
  1998年   18506篇
  1997年   16460篇
  1996年   16948篇
  1995年   15926篇
  1994年   15050篇
  1993年   14070篇
  1992年   53056篇
  1991年   52921篇
  1990年   52578篇
  1989年   50958篇
  1988年   47462篇
  1987年   46575篇
  1986年   44303篇
  1985年   42359篇
  1984年   31460篇
  1983年   27304篇
  1982年   15947篇
  1981年   14276篇
  1979年   30146篇
  1978年   21382篇
  1977年   18371篇
  1976年   17465篇
  1975年   19343篇
  1974年   22877篇
  1973年   21918篇
  1972年   20956篇
  1971年   19646篇
  1970年   18324篇
  1969年   17674篇
  1968年   16612篇
  1967年   14702篇
  1966年   13446篇
排序方式: 共有10000条查询结果,搜索用时 640 毫秒
21.
22.
Bulletin of Experimental Biology and Medicine - Ammonium, an end-product of catabolism, in low doses can promote adaptation of metabolic pathways in erythrocytes under conditions of extreme...  相似文献   
23.

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   
24.
25.
Erosive pustular dermatosis of the scalp (EPDS) is an uncommon chronic inflammatory response to scalp trauma that usually resolves with cicatricial alopecia. It most commonly affects elderly patients with a history of actinic damage. Herein, we describe a 16‐year‐old girl with acrofacial dysostosis type 1 presenting after surgery with crusting purulent scalp lesions, whose clinical presentation and histopathologic findings were consistent with EPDS. A review of the literature on EPDS in children is also detailed.  相似文献   
26.

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   
27.
28.
29.
30.
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