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   19909篇
  免费   1475篇
  国内免费   51篇
耳鼻咽喉   158篇
儿科学   705篇
妇产科学   573篇
基础医学   2621篇
口腔科学   356篇
临床医学   3078篇
内科学   3443篇
皮肤病学   228篇
神经病学   1393篇
特种医学   709篇
外国民族医学   2篇
外科学   2450篇
综合类   287篇
一般理论   48篇
预防医学   2419篇
眼科学   498篇
药学   1190篇
中国医学   21篇
肿瘤学   1256篇
  2023年   86篇
  2022年   124篇
  2021年   323篇
  2020年   210篇
  2019年   360篇
  2018年   424篇
  2017年   308篇
  2016年   345篇
  2015年   383篇
  2014年   549篇
  2013年   893篇
  2012年   1197篇
  2011年   1368篇
  2010年   729篇
  2009年   704篇
  2008年   1261篇
  2007年   1222篇
  2006年   1161篇
  2005年   1244篇
  2004年   1212篇
  2003年   1091篇
  2002年   1053篇
  2001年   321篇
  2000年   326篇
  1999年   296篇
  1998年   238篇
  1997年   207篇
  1996年   171篇
  1995年   154篇
  1994年   145篇
  1993年   138篇
  1992年   216篇
  1991年   174篇
  1990年   191篇
  1989年   194篇
  1988年   169篇
  1987年   162篇
  1986年   146篇
  1985年   161篇
  1984年   146篇
  1983年   141篇
  1982年   114篇
  1981年   112篇
  1980年   94篇
  1979年   111篇
  1978年   111篇
  1976年   81篇
  1975年   79篇
  1974年   82篇
  1973年   72篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.

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   
3.
4.
DNA methylation at CpG dinucleotides is an important epigenetic regulator common to virtually all mammalian cell types, but recent evidence indicates that during early postnatal development neuronal genomes also accumulate uniquely high levels of two alternative forms of methylation, non-CpG methylation and hydroxymethylation. Here we discuss the distinct landscape of DNA methylation in neurons, how it is established, and how it might affect the binding and function of protein readers of DNA methylation. We review studies of one critical reader of DNA methylation in the brain, the Rett syndrome protein methyl CpG-binding protein 2 (MeCP2), and discuss how differential binding affinity of MeCP2 for non-CpG and hydroxymethylation may affect the function of this methyl-binding protein in the nervous system.  相似文献   
5.
6.
7.
Since the 1990s, oral rabies vaccination (ORV) has been used successfully to halt the westward spread of the raccoon rabies virus (RV) variant from the eastern continental USA. Elimination of raccoon RV from the eastern USA has proven challenging across targeted raccoon (Procyon lotor) and striped skunk (Mephitis mephitis) populations impacted by raccoon RV. Field trial evaluations of the Ontario Rabies Vaccine Bait (ONRAB) were initiated to expand ORV products available to meet the rabies management goal of raccoon RV elimination. This study describes the continuation of a 2011 trial in West Virginia. Our objective was to evaluate raccoon and skunk response to ORV occurring in West Virginia for an additional two years (2012–2013) at 75 baits/km2 followed by three years (2014–2016) of evaluation at 300 baits/km2. We measured the change in rabies virus-neutralizing antibody (RVNA) seroprevalence in targeted wildlife populations by comparing levels pre- and post-ORV during each year of study. The increase in bait density from 75/km2 to 300/km2 corresponded to an increase in average post-ORV seroprevalence for raccoon and skunk populations. Raccoon population RVNA levels increased from 53% (300/565, 95% CI: 50–57%) to 82.0% (596/727, 95% CI: 79–85%) during this study, and skunk population RVNA levels increased from 11% (8/72, 95% CI: 6–20%) to 39% (51/130, 95% CI: 31–48%). The RVNA seroprevalence pre-ORV demonstrated an increasing trend across study years for both bait densities and species, indicating that multiple years of ORV may be necessary to achieve and maintain RVNA seroprevalence in target wildlife populations for the control and elimination of raccoon RV in the eastern USA.  相似文献   
8.
9.
Objective: To investigate on the feasibility, safety, and effectiveness of a new bioabsorbable material for lung staple-line reinforcement. Methods: This prospective open trial included 66 patients (mean age of 56 ± 17 years) who underwent various types of lung resection using staplers with knitted calcium alginate sleeves for buttressing (FOREseal™, Laboratoires Brothier, Nanterre, France) at three academic centers: 29 lobectomies, 22 emphysema surgeries, 15 wedge resections or lung biopsies. Intraoperative air leakage was assessed at a mean respiratory peak pressure of 30 cmH2O, and rated as grade 1, 2, or 3. Persistent air leakage in the postoperative course, as well as any relevant event, was assessed daily. The follow-up period was of 6 months. Results: No technical problem linked to the device occurred. Hemostasis of the cutting edges was completed in all patients. Fifty-six percent of the patients had no intraoperative air leak and 27.3% had grade 1 leaks. Mean postoperative air leaks and thoracic drainage times were 1.9 ± 2.3 days and 6 ± 5.3 days, respectively. In-hospital mortality was nil. There was no empyema. Mean hospital stay was 9.1 ± 6.6 days. At follow-up, one patient underwent lung transplantation, and pathology of the explanted specimen showed the absence of device-related foreign-body inflammation. One patient complained from metalloptysis, and another one, with a metastatic invasive aspergillosis, developed an infectious recurrence that required reoperation. Conclusions: FOREseal is an ergonomic, safe, and promising new material instead of nonabsorbable materials and xenomaterials for staple-line reinforcement. A randomized comparative study is now in progress.  相似文献   
10.
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