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   13508篇
  免费   1113篇
  国内免费   25篇
耳鼻咽喉   187篇
儿科学   533篇
妇产科学   376篇
基础医学   1648篇
口腔科学   115篇
临床医学   1513篇
内科学   2414篇
皮肤病学   254篇
神经病学   1548篇
特种医学   293篇
外科学   1487篇
综合类   86篇
一般理论   20篇
预防医学   2100篇
眼科学   324篇
药学   807篇
  1篇
中国医学   15篇
肿瘤学   925篇
  2024年   47篇
  2023年   315篇
  2022年   475篇
  2021年   927篇
  2020年   535篇
  2019年   788篇
  2018年   853篇
  2017年   571篇
  2016年   589篇
  2015年   569篇
  2014年   713篇
  2013年   865篇
  2012年   1255篇
  2011年   1223篇
  2010年   588篇
  2009年   480篇
  2008年   774篇
  2007年   710篇
  2006年   545篇
  2005年   495篇
  2004年   402篇
  2003年   327篇
  2002年   251篇
  2001年   34篇
  2000年   23篇
  1999年   22篇
  1998年   38篇
  1997年   26篇
  1996年   17篇
  1995年   20篇
  1994年   17篇
  1993年   18篇
  1992年   8篇
  1991年   9篇
  1990年   6篇
  1989年   7篇
  1987年   3篇
  1986年   3篇
  1985年   5篇
  1984年   6篇
  1983年   8篇
  1982年   13篇
  1981年   7篇
  1980年   8篇
  1979年   3篇
  1978年   7篇
  1976年   5篇
  1973年   3篇
  1972年   3篇
  1924年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Three new sterol sulfates, spheciosterol sulfates A-C (1-3), and the known sterol sulfate topsentiasterol sulfate E (4) have been isolated from the sponge Spheciospongia sp., collected in the Philippines. Structures were assigned on the basis of extensive 1D and 2D NMR studies as well as analysis by HRESIMS. Compounds 1-4 inhibited PKCzeta with IC50 values of 1.59, 0.53, 0.11, and 1.21 microM, respectively. In a cell-based assay, 1-4 also inhibited NF-kappaB activation with EC50 values of 12-64 microM.  相似文献   
52.
53.
54.
55.
STUDY OBJECTIVE: Bacterial vaginosis (BV) is a common infection and has been associated with adverse health outcomes, including preterm birth, pelvic inflammatory disease (PID), and acquisition of HIV. There are limited data on recurrent BV in adolescents. A relationship between the frequency of BV recurrence and specific risk factors might shed light on the pathophysiology of BV and lead to targeted interventions. METHODS: Design: Record-based historical clinic study. Setting: Adolescent visits to two sexually transmitted disease (STD) clinics between 1990 and 2002. Participants: 254 girls who had >/= 2 episodes of BV and at least 3 clinical visits, matched on clinic attendance frequency to 254 girls with only 1 documented BV episode and 254 girls with no history of BV. MAIN OUTCOME MEASURE: Risk factor differences between groups. ANALYSIS: Multinomial logistic regression with robust estimator of the standard errors, accounting for repeated measures. RESULTS: 5,977 adolescent girls visited the clinics. 1509 (25%) had at least one episode of BV; of those, 303 (19.9%) had 2 or more BV episodes. Girls with a history of 1 BV episode and girls with a history of 2 or more BV episodes were more likely to be infected with Trichomonas vaginalis [OR 1.77, 95% CI: 1.17-2.67, OR 1.56, 95% CI: 1.05-2.34] and be diagnosed with PID [OR 1.50, 95% CI: 1.02-2.22, OR 2.05, 95% CI: 1.41-2.98] compared to girls with no BV history, respectively. Girls with a history of BV were also more likely to report active oral sex and lack of contraceptive use. CONCLUSION: Adolescent girls who attend STD clinics have a high prevalence of BV. Although the association between BV and PID is not clearly causal, when one condition is diagnosed, evaluation and counseling for the other may reduce recurrence and sequelae.  相似文献   
56.
57.
58.
59.
60.
A COVID-19 outbreak occurred among Cameron Peak Fire responders in Colorado, USA, during August 2020–January 2021. The Cameron Peak Fire was the largest recorded wildfire in Colorado history, lasting August–December 2020. At least 6,123 responders were involved, including 1,260 firefighters in 63 crews who mobilized to the fire camps. A total of 79 COVID-19 cases were identified among responders, and 273 close contacts were quarantined. State and local public health investigated the outbreak and coordinated with wildfire management teams to prevent disease spread. We performed whole-genome sequencing and applied social network analysis to visualize clusters and transmission dynamics. Phylogenetic analysis identified 8 lineages among sequenced specimens, implying multiple introductions. Social network analysis identified spread between and within crews. Strategies such as implementing symptom screening and testing of arriving responders, educating responders about overlapping symptoms of smoke inhalation and COVID-19, improving physical distancing of crews, and encouraging vaccinations are recommended.  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