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   21050篇
  免费   1564篇
  国内免费   143篇
耳鼻咽喉   166篇
儿科学   712篇
妇产科学   669篇
基础医学   2929篇
口腔科学   270篇
临床医学   2172篇
内科学   4805篇
皮肤病学   337篇
神经病学   1806篇
特种医学   591篇
外科学   2607篇
综合类   343篇
一般理论   3篇
预防医学   1638篇
眼科学   469篇
药学   1360篇
中国医学   114篇
肿瘤学   1766篇
  2023年   175篇
  2022年   286篇
  2021年   653篇
  2020年   420篇
  2019年   609篇
  2018年   644篇
  2017年   490篇
  2016年   552篇
  2015年   599篇
  2014年   781篇
  2013年   1039篇
  2012年   1526篇
  2011年   1578篇
  2010年   855篇
  2009年   737篇
  2008年   1227篇
  2007年   1337篇
  2006年   1186篇
  2005年   1086篇
  2004年   1058篇
  2003年   917篇
  2002年   886篇
  2001年   425篇
  2000年   379篇
  1999年   378篇
  1998年   193篇
  1997年   205篇
  1996年   160篇
  1995年   131篇
  1994年   121篇
  1993年   80篇
  1992年   201篇
  1991年   184篇
  1990年   150篇
  1989年   137篇
  1988年   130篇
  1987年   132篇
  1986年   100篇
  1985年   85篇
  1984年   76篇
  1983年   78篇
  1982年   64篇
  1981年   54篇
  1980年   50篇
  1979年   84篇
  1978年   52篇
  1977年   46篇
  1976年   43篇
  1974年   44篇
  1973年   41篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
The retroviral protease of human immunodeficiency virus (HIV) is an excellent target for antiviral inhibitors for treating HIV/AIDS. Despite the efficacy of therapy, current efforts to control the disease are undermined by the growing threat posed by drug resistance. This review covers the historical background of studies on the structure and function of HIV protease, the subsequent development of antiviral inhibitors, and recent studies on drug-resistant protease variants. We highlight the important contributions of Dr. Stephen Oroszlan to fundamental knowledge about the function of the HIV protease and other retroviral proteases. These studies, along with those of his colleagues, laid the foundations for the design of clinical inhibitors of HIV protease. The drug-resistant protease variants also provide an excellent model for investigating the molecular mechanisms and evolution of resistance.  相似文献   
6.
7.
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   
8.
9.
10.
Purpose of the study: the aim of this study was to synthesize PFC fNIRS outcomes on the effects of cognitive tasks compared to resting/baseline tasks in healthy adults from studies utilizing a pre/post design.

Material and methods: original research studies were searched from seven databases (MEDLINE, EMBASE, CENTRAL, CINAHL, SCOPUS, PEDro and PubMed). Subsequently, two independent reviewers screened the titles and abstracts followed by full-text reviews to assess the studies' eligibility.

Results: eleven studies met the inclusion criteria and had data abstracted and quality assessed. Methodology varied considerably and yet cognitive tasks resulted in the ΔO2Hb increasing in 8 of the 11 and ΔHHb decreasing in 8 of 8 studies that reported this outcome. The cognitive tasks from 10 of the 11 studies were classified as “Working Memory” and “Verbal Fluency Tasks”.

Conclusions: although, the data comparison was challenging provided the heterogeneity in methodology, the results across studies were similar.  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