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   13319篇
  免费   949篇
  国内免费   57篇
耳鼻咽喉   97篇
儿科学   514篇
妇产科学   460篇
基础医学   1815篇
口腔科学   207篇
临床医学   1646篇
内科学   2694篇
皮肤病学   290篇
神经病学   1441篇
特种医学   410篇
外科学   1103篇
综合类   135篇
一般理论   2篇
预防医学   1084篇
眼科学   367篇
药学   907篇
中国医学   28篇
肿瘤学   1125篇
  2023年   140篇
  2022年   230篇
  2021年   471篇
  2020年   305篇
  2019年   437篇
  2018年   420篇
  2017年   332篇
  2016年   380篇
  2015年   414篇
  2014年   520篇
  2013年   743篇
  2012年   1047篇
  2011年   1078篇
  2010年   567篇
  2009年   464篇
  2008年   839篇
  2007年   880篇
  2006年   758篇
  2005年   679篇
  2004年   663篇
  2003年   598篇
  2002年   595篇
  2001年   126篇
  2000年   105篇
  1999年   139篇
  1998年   111篇
  1997年   90篇
  1996年   70篇
  1995年   60篇
  1994年   60篇
  1993年   57篇
  1992年   81篇
  1991年   80篇
  1990年   56篇
  1989年   53篇
  1988年   45篇
  1987年   53篇
  1986年   31篇
  1985年   60篇
  1984年   44篇
  1983年   30篇
  1982年   37篇
  1981年   34篇
  1980年   34篇
  1979年   23篇
  1978年   26篇
  1977年   19篇
  1976年   19篇
  1975年   21篇
  1974年   21篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Background: Egyptian street youth use substances including tobacco, illicit drugs, and pharmaceutical drugs. To understand the circumstances, including adverse childhood experiences, that place adolescents at risk for engaging in substance use, we conducted in-depth interviews among a sample of Egyptian street children. Methods: From youth residing at or attending Caritas, a non-profit organization, which provides shelter and education to street youth, seven girls and twelve boys, aged 12–18 years, participated in open-ended, in-depth interviews. Results: Eight out of the 19 participants reported family history (early exposure) to substance use; and seven of them were initiated by either a family member (sibling), friend or coworker. Most of the participants reported a history of conflict with or abuse (verbal or physical) by their parents or siblings, or stressful situations at home; they used substance(s) to alleviate their stress. Few attended school, and some were forced to work and help their family. Conclusions: Among Egyptian youth, adverse childhood experiences, such as poverty, child abuse, and family substance use, challenge somewhat susceptible youths and lead them to the path of substance use and addiction. Prevention intervention should be multifaceted, culturally adaptable, and primarily targeting the social environment during childhood.  相似文献   
5.
6.
7.

Objectives

Short successive periods of skeletal muscle disuse have been suggested to substantially contribute to the observed loss of skeletal muscle mass over the life span. Hospitalization of older individuals due to acute illness, injury, or major surgery generally results in a mean hospital stay of 5 to 7 days, during which the level of physical activity is strongly reduced. We hypothesized that hospitalization following elective total hip arthroplasty is accompanied by substantial leg muscle atrophy in older men and women.

Design and participants

Twenty-six older patients (75 ± 1 years) undergoing elective total hip arthroplasty participated in this observational study.

Measurements

On hospital admission and on the day of discharge, computed tomographic (CT) scans were performed to assess muscle cross-sectional area (CSA) of both legs. During surgery and on the day of hospital discharge, a skeletal muscle biopsy was taken from the m. vastus lateralis of the operated leg to assess muscle fiber type–specific CSA.

Results

An average of 5.6 ± 0.3 days of hospitalization resulted in a significant decline in quadriceps (?3.4% ± 1.0%) and thigh muscle CSA (?4.2% ± 1.1%) in the nonoperated leg (P < .05). Edema resulted in a 10.3% ± 1.7% increase in leg CSA in the operated leg (P < .05). At hospital admission, muscle fiber CSA was smaller in the type II vs type I fibers (3326 ± 253 μm2 vs 4075 ± 279 μm2, respectively; P < .05). During hospitalization, type I and II muscle fiber CSA tended to increase, likely due to edema in the operated leg (P = .10).

Conclusions

Six days of hospitalization following elective total hip arthroplasty leads to substantial leg muscle atrophy in older patients. Effective intervention strategies are warranted to prevent the loss of muscle mass induced by short periods of muscle disuse during hospitalization.  相似文献   
8.
9.
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