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   14938篇
  免费   1278篇
  国内免费   33篇
耳鼻咽喉   137篇
儿科学   477篇
妇产科学   470篇
基础医学   2027篇
口腔科学   230篇
临床医学   1982篇
内科学   2715篇
皮肤病学   275篇
神经病学   1794篇
特种医学   232篇
外科学   1397篇
综合类   133篇
一般理论   22篇
预防医学   2099篇
眼科学   133篇
药学   986篇
中国医学   27篇
肿瘤学   1113篇
  2024年   34篇
  2023年   206篇
  2022年   388篇
  2021年   727篇
  2020年   460篇
  2019年   674篇
  2018年   695篇
  2017年   485篇
  2016年   519篇
  2015年   599篇
  2014年   775篇
  2013年   973篇
  2012年   1394篇
  2011年   1346篇
  2010年   743篇
  2009年   576篇
  2008年   931篇
  2007年   858篇
  2006年   757篇
  2005年   683篇
  2004年   602篇
  2003年   459篇
  2002年   370篇
  2001年   82篇
  2000年   58篇
  1999年   74篇
  1998年   67篇
  1997年   58篇
  1996年   47篇
  1995年   38篇
  1994年   36篇
  1993年   38篇
  1992年   24篇
  1991年   23篇
  1990年   23篇
  1989年   26篇
  1988年   29篇
  1987年   22篇
  1985年   18篇
  1983年   17篇
  1982年   14篇
  1980年   13篇
  1979年   15篇
  1976年   18篇
  1973年   15篇
  1971年   15篇
  1970年   30篇
  1969年   30篇
  1968年   34篇
  1967年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Introduction: Current research suggests that pediatric stroke is associated with a reduction in intellectual functioning. However, less is known about academic achievement and the contribution of specific executive functions to math and literacy in this population. The current study investigates behavioral ratings of executive functioning and their relationship to math and spelling performance in children with a history of unilateral arterial ischemic stroke.

Method: Thirty-two pediatric patients with stroke (Mage = 9.5 ± 2.7 years) and 32 demographically equivalent, healthy controls were tested on standardized measures of arithmetic, spelling, and intelligence. Executive functioning data were collected via standardized parent questionnaire.

Results: Relative to controls, stroke participants demonstrated significantly poorer functioning in math, spelling, metacognition, and behavioral-regulation. Pencil and paper arithmetic was particularly challenging for the stroke group, with 40% of patients reaching levels of clinical impairment. Hierarchical regression in stroke participants further revealed that metacognition was a robust predictor of academic deficits. Stroke occurring in later childhood and affecting cortical and subcortical brain regions also presented as potential clinical risk factors.

Conclusions: Children with stroke were especially vulnerable to math achievement deficits. Metacognition made a substantial contribution to academic achievement abilities among stroke patients, and results underscore the importance of early metacognitive skills in the completion of schoolwork. Results also emphasize that pediatric stroke patients are a heterogeneous group with regard to functioning and that there is value in examining standard score distributions of clinical participant samples.  相似文献   

2.

Introduction

In the United States there has been a large increase in participation in lacrosse for both males and females. The purpose of this study was to analyze the number of head injuries, injury rates (calculated using the reported number of participants) and types of head injuries that are seen in emergency departments in the United States.

Methods

We compared injuries between male and female lacrosse participants. This was a retrospective study using a publicly available database produced by the US Consumer Product Safety Commission and information about lacrosse participation from US Lacrosse.

Results

A linear regression was performed and showed a positive correlation between number of head injuries to males and time from 2002 to 2010 (R2?=?0.823; p?=?0.001). While the number of injuries to the head in female lacrosse participants was not significant. There was a negative correlation between the number of head injuries to males from 2010 to 2016 (R2?=?0.800; p?=?0.007), but again, there was no significance for female injury count (R2?=?0.417; p?=?0.117). Other significant differences between head injuries in males and females included the mechanism of injury and the type of injury recorded.

Conclusion

The most recent data from 2010 to 2016, suggest that both males and females have had a decrease in injury rate. However the total number of female head injuries is not significantly decreasing and as the sport continues to grow there will likely be more total head injuries and visits to the emergency department.  相似文献   
3.
For patients who receive a liver transplant (LTX) for alcoholic liver disease (ALD), investigators are focusing beyond survival to determine specific alcohol use outcomes. Studies suggest the use of alcohol ranges from 8 to 22% for the first post-transplant year with cumulative rates reaching 30 to 40% by 5 years following transplantation. Yet while investigators are interested in determining specific rates of alcohol use and predictors of use, only three studies since 1990 have been prospective. In 1998, we began a prospective study of post-LTX alcohol consumption in ALD recipients using multiple repeated measures of alcohol use. After 5 years of follow-up, we found that 22% had used any alcohol by the first year and 42% had a drink by 5 years. By 5 years, 26% drank at a heavier use (binge) pattern and 20% drank in a frequent pattern. In a univariate model, predictors of alcohol use included pre-transplant length of sobriety, a diagnosis of alcohol dependence, a history of other substance use, and prior alcohol rehabilitation.  相似文献   
4.
5.
6.
7.

Background  

The telomeric region of mouse chromosome 12 has previously shown frequent allelic loss in murine lymphoma. The Bcl11b gene has been identified and suggested as a candidate tumor suppressor gene within this region. In this study, we aimed to elucidate whether Bcl11b is mutated in lymphomas with allelic loss, and whether the mutations we detected conferred any effect on cell proliferation and apoptosis.  相似文献   
8.
The surgical risk of colectomy in patients with cirrhosis   总被引:5,自引:1,他引:4  
The records of 54 patients with documented cirrhosis who underwent colectomy between January 1970 and January 1984 were studied to assess the operative risk and to determine the preoperative predictive risk factors. In-hospital mortality was 24 percent (13 patients), and postoperative complications occurred in 48 percent (26 patients). The risk of surgical intervention was significantly increased if encephalopathy, ascites, anemia, or hypoalbuminemia was present before operation. A simple operative risk index involving the presence of encephalopathy and ascites and the levels of hemoglobin and albumin is proposed to help distinguish a low-risk subgroup in whom postoperative mortality was 12.8 percent from a high-risk subgroup in whom postoperative mortality was 53.3 percent.  相似文献   
9.
Objective: To determine the effect of indwelling versus intermittent feeding tube placement on weight gain, apnea, and bradycardia in premature neonates.
Design: Eligible subjects were assigned randomly to either feeding tube method. Each subject was followed for 6 days.
Setting: The study was conducted in a secondary level neonatal intensive-care unit (NICU), a tertiary level NICU in a perinatal center, and a tertiary level NICU in a referral center.
Patients/Participants: Neonates who were 24–34 weeks gestational age, developmentally appropriate for gestational age, medically stable, on full enteral feedings through an orogastric or a nasogastric tube, and not fluid restricted. Ninety-three neonates were enrolled-49 in the indwelling group and 44 in the intermittent group. Nine neonates did not complete the study.
Interventions: Nasogastric indwelling feeding tubes were placed and left in site for up to 3 days. Orogastric intermittent feeding tubes were placed for each feeding and removed at completion of the feeding.
Main outcome measures: Weight gain, apnea, and bradycardia. Results: Members of both groups had similar demographic characteristics, clinical problems, and nutritional intake. No statistical differences were found between the two groups in weight gain or episodes of apnea and bradycardia.
Conclusions: There were no statistically or clinically significant differences between the two groups. The intermittent method of feeding is more expensive. Because no clinical differences were found, the type of tube placement chosen for feeding the premature infant may be based on economics.  相似文献   
10.
Body pain and treatment response in late-life depression.   总被引:2,自引:0,他引:2  
OBJECTIVE: The authors investigated the influence of body pain on 1) time to treatment response and 2) suicidal ideation, in late-life depression. They hypothesized that higher levels of body pain would predict a longer time to and lower likelihood of response, and increased levels of suicidal ideation. METHODS: Subjects (N=187) were older adult outpatients (age > or =69 years), with current episodes of major depression, who were openly treated with paroxetine up to 40 mg daily and weekly interpersonal psychotherapy. Response was defined as 3 consecutive weeks of Hamilton Rating Scale for Depression at < or =10. Body pain was measured with the Bodily Pain Index of the SF-36 quality-of-life assessment. Authors used survival-analysis models on the responder sample to test the effect of body pain on response, after controlling for severity of depression. RESULTS: Overall response rate was 75.4%. Nonresponders reported more severe pain at baseline. After covarying for severity of baseline depression, no effect was found for physical pain on time-to-response or degree of suicidality. Bodily pain remained stable during acute treatment for responders, independent of depression response to combination psychotherapy and antidepressant treatment. CONCLUSIONS: Older adult patients with higher levels of physical pain can still respond to antidepressant treatment; however, reported bodily pain may be associated with a more difficult-to-treat depression.  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