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   3348117篇
  免费   271091篇
  国内免费   14536篇
耳鼻咽喉   46173篇
儿科学   98809篇
妇产科学   83758篇
基础医学   536016篇
口腔科学   91144篇
临床医学   298693篇
内科学   586340篇
皮肤病学   90204篇
神经病学   284869篇
特种医学   132922篇
外国民族医学   105篇
外科学   525771篇
综合类   97756篇
现状与发展   28篇
一般理论   2224篇
预防医学   271135篇
眼科学   77074篇
药学   234517篇
  24篇
中国医学   10986篇
肿瘤学   165196篇
  2022年   24948篇
  2021年   57880篇
  2020年   36333篇
  2019年   59801篇
  2018年   72896篇
  2017年   55435篇
  2016年   61796篇
  2015年   77289篇
  2014年   111953篇
  2013年   177678篇
  2012年   93976篇
  2011年   92118篇
  2010年   118850篇
  2009年   123173篇
  2008年   77770篇
  2007年   79347篇
  2006年   90013篇
  2005年   85034篇
  2004年   86297篇
  2003年   76744篇
  2002年   66265篇
  2001年   105372篇
  2000年   98194篇
  1999年   97579篇
  1998年   64974篇
  1997年   62789篇
  1996年   60528篇
  1995年   55980篇
  1994年   49931篇
  1993年   46606篇
  1992年   67301篇
  1991年   63639篇
  1990年   60010篇
  1989年   59530篇
  1988年   54928篇
  1987年   53557篇
  1986年   50448篇
  1985年   50808篇
  1984年   46274篇
  1983年   42627篇
  1982年   40686篇
  1981年   38356篇
  1980年   36072篇
  1979年   37210篇
  1978年   33268篇
  1977年   31028篇
  1976年   27808篇
  1975年   26347篇
  1974年   26798篇
  1973年   25451篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
Potential for widespread transmission of HIV/AIDS among American Indian (AI) adolescents exists, yet no evidence-based interventions (EBIs) have been adapted and evaluated with this population. Intensive psychoeducation may improve knowledge and decision-making which could potentially translate to reductions in HIV risk behaviors. A peer group randomized controlled comparison of an adapted EBI vs. control was delivered over an eight-day summer basketball camp in one reservation-based tribal community to adolescents ages 13–19. Outcome data were gathered immediately post-camp and at 6 and 12 months follow-up. Self-selected peer groups were randomized to intervention (n = 138) or control (n = 129) conditions for a total sample of 267 participants (56.2% female), mean age 15.1 years (SD = 1.7). Intervention participants had better condom use self-efficacy post-camp (Adjusted Mean Difference [AMD] = ?0.75, p < 0.005) and at 6 (AMD = ?0.44, p < 0.005) and 12 months (AMD = ?0.23, p < 0.05) follow-up. Intervention participants also had higher HIV prevention and transmission knowledge (post-camp: AMD = 0.07, p < 0.01; 6 months: AMD = 0.06, p < 0.01) were more likely to believe condoms prevent sexually transmitted infections (post-camp: RR = 1.41, p < 0.005; 6 months: RR = 1.34, p < 0.05), to talk with an adult about HIV/AIDS (post-camp: RR=1.78, p < 0.005; 6 months: RR = 1.14, p < 0.005), had higher partner negotiation efficacy related to substance use during sex (post-camp: AMD = 0.37, p < 0.01), and were more likely to intend to use a condom (post-camp: RR = 1.39, p < 0.01). The adapted intervention had short- and medium-term impacts on AI adolescent risk for HIV/AIDS, but attenuated at 12 months. Intervention delivery through a community-based camp is feasible and acceptable with strong retention. Additional study is needed to evaluate the adapted intervention's impact on sexual risk behaviors and if booster sessions and parent involvement translate to long-term impacts.  相似文献   
23.
24.
25.
26.
27.
Sinus venosus atrial septal defect (SV‐ASD) usually coexists with partial anomalous pulmonary vein connection (PAPVC). It is a difficult diagnosis in transthoracic echocardiography (TTE) due to eccentric position of defects. We present a rare case of atypical anatomical variation in PAPVC, which was never described before. Two right pulmonary veins drained into superior vena cava, which overrode SV‐ASD and interatrial septum, a third pulmonary vein into the right atrium. Complete diagnosis could not be set after TTE, nor transesophageal echocardiography, whereas angio‐CT was finally conclusive. This diagnostic approach allowed the surgical planning.  相似文献   
28.
29.
30.
Hepatic NADPH-cytochrome P450 oxidoreductase null (HRN?) mice exhibit normal hepatic and extrahepatic biotransformation enzyme activities when compared to wild-type (WT) mice, but express no functional hepatic cytochrome P450 activities. When incubated in vitro with [14C]-diclofenac, liver microsomes from WT mice exhibited extensive biotransformation to oxidative and glucuronide metabolites and covalent binding to proteins was also observed. In contrast, whereas glucuronide conjugates and a quinone-imine metabolite were formed when [14C]-diclofenac was incubated with HRN? mouse liver, only small quantities of P450-derived oxidative metabolites were produced in these samples and covalent binding to proteins was not observed. Livers from vehicle-treated HRN? mice exhibited enhanced lipid accumulation, bile duct proliferation, hepatocellular degeneration and necrosis and inflammatory cell infiltration, which were not present in livers from WT mice. Elevated liver-derived alanine aminotransferase, glutamate dehydrogenase and alkaline phosphatase activities were also observed in plasma from HRN? mice. When treated orally with diclofenac for 7 days, at 30 mg/kg/day, the severities of the abnormal liver histopathology and plasma liver enzyme findings in HRN? mice were reduced markedly. Oral diclofenac administration did not alter the liver histopathology or elevate plasma enzyme activities of WT mice. These findings indicate that HRN? mice are valuable for exploration of the role played by hepatic P450s in drug biotransformation, but poorly suited to investigations of drug-induced liver toxicity. Nevertheless, studies in HRN? mice could provide novel insights into the role played by inflammation in liver injury and may aid the evaluation of new strategies for its treatment.  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