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   46808篇
  免费   4778篇
  国内免费   2187篇
耳鼻咽喉   330篇
儿科学   696篇
妇产科学   674篇
基础医学   5174篇
口腔科学   890篇
临床医学   4442篇
内科学   7966篇
皮肤病学   624篇
神经病学   2611篇
特种医学   1924篇
外国民族医学   16篇
外科学   7838篇
综合类   7848篇
现状与发展   8篇
预防医学   2193篇
眼科学   1648篇
药学   4214篇
  13篇
中国医学   2021篇
肿瘤学   2643篇
  2024年   54篇
  2023年   686篇
  2022年   941篇
  2021年   1737篇
  2020年   1696篇
  2019年   1612篇
  2018年   1571篇
  2017年   1461篇
  2016年   1601篇
  2015年   1686篇
  2014年   2895篇
  2013年   3284篇
  2012年   2607篇
  2011年   2886篇
  2010年   2467篇
  2009年   2470篇
  2008年   2595篇
  2007年   2604篇
  2006年   2491篇
  2005年   2339篇
  2004年   1989篇
  2003年   1714篇
  2002年   1495篇
  2001年   1245篇
  2000年   1119篇
  1999年   891篇
  1998年   707篇
  1997年   660篇
  1996年   524篇
  1995年   510篇
  1994年   389篇
  1993年   348篇
  1992年   325篇
  1991年   289篇
  1990年   214篇
  1989年   167篇
  1988年   174篇
  1987年   162篇
  1986年   124篇
  1985年   181篇
  1984年   147篇
  1983年   116篇
  1982年   109篇
  1981年   134篇
  1980年   95篇
  1979年   65篇
  1978年   55篇
  1977年   46篇
  1976年   37篇
  1975年   16篇
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
1.
阿尔茨海默病是一种进行性且不可逆转的神经系统疾病,由于视网膜和中枢神经系统有相似的胚胎起源和生理特征,眼科检查可提供简单无创的诊断方法。光学相干断层扫描技术(OCT)能够精确地测量视网膜各个组织层面的厚度,以评估视网膜的退行性改变,光学相干断层扫描血管成像(OCTA)可以提供高分辨率三维成像,从而更直观地检测视网膜血管的变化,间接地反映脑神经元和血管的病理特征。就OCT测量视网膜厚度及OCTA测量视网膜血流变化在阿尔茨海默病诊断中的研究进展进行综述。  相似文献   
2.
Tamoxifen prevents recurrence of breast cancer and is suggested for preventive risk-reducing therapy. Tamoxifen reduces mammographic density, a proxy for therapy response, but little is known about its effects in remodelling normal breast tissue. Our study, a substudy within the double-blinded dose-determination trial KARISMA, investigated tamoxifen-specific changes in breast tissue composition and histological markers in healthy women. We included 83 healthy women randomised to 6 months daily intake of 20, 10, 5, 2.5, 1 mg of tamoxifen or placebo. The groups were combined to “no dose” (0-1 mg), “low-dose” (2.5-5 mg) or “high-dose” (10-20 mg) of tamoxifen. Ultrasound-guided biopsies were collected before and after tamoxifen exposure. In each biopsy, epithelial, stromal and adipose tissues was quantified, and expression of epithelial and stromal Ki67, oestrogen receptor (ER) and progesterone receptor (PR) analysed. Mammographic density using STRATUS was measured at baseline and end-of-tamoxifen-exposure. We found that different doses of tamoxifen reduced mammographic density and glandular-epithelial area in premenopausal women and associated with reduced epithelium and increased adipose tissue. High-dose tamoxifen also decreased epithelial ER and PR expressions in premenopausal women. Premenopausal women with the greatest reduction in proliferation also had the greatest epithelial reduction. In postmenopausal women, high-dose tamoxifen decreased the epithelial area with no measurable density decrease. Tamoxifen at both low and high doses influences breast tissue composition and expression of histological markers in the normal breast. Our findings connect epithelial proliferation with tissue remodelling in premenopausal women and provide novel insights to understanding biological mechanisms of primary prevention with tamoxifen.  相似文献   
3.
《Pancreatology》2022,22(8):1175-1180
BackgroundHepatic steatosis has been described as a common finding in adults following total pancreatectomy with islet autotransplantation (TPIAT) but it is unknown if this occurs in children and adolescents.ObjectivesTo define the frequency of post-TPIAT hepatic steatosis in a sample of children and adolescents and to identify clinical predictors of incident steatosis post-TPIAT.MethodsIn this prospective study, consecutive participants at least 1-month post-TPIAT underwent a liver MRI with proton density fat fraction (PDFF) and blood draw at our pediatric academic medical center between April 2021 and January 2022. Comparison clinical pre-TPIAT liver MRI or ultrasound and insulin use and graft function data were extracted from the medical record. T-tests were used for the comparison of means across continuous variables between participants with and without post-TPIAT steatosis.ResultsA total of 20 participants (mean: 13 ± 4 years; 12 female) were evaluated. Mean liver PDFF at research MRI was 7.4 ± 6.2% (range: 2–25%). Seven participants (35%) had categorical hepatic steatosis (PDFF>5%) post-TPIAT, five of whom had pre-TPIAT steatosis, reflecting a 13% (2/15; 95% CI: 2–40%) incidence of post-TPIAT steatosis. Participant characteristics were not significantly different between subgroups with and without post-TPIAT steatosis. Mean PDFF at research MRI was not different between graft function subgroups (7.5% optimal/good vs. 7.3% marginal/failure; p = .96).ConclusionOur study shows a moderate prevalence but low incidence of hepatic steatosis in a small sample of children and adolescents post-TPIAT. This study raises questions about a causal relationship between TPIAT and hepatic steatosis.  相似文献   
4.
5.
6.
7.
8.
9.
目的:探究复方丹参滴丸对老年冠心病患者血流变学、血脂及炎性反应递质的影响。方法:选取2015年1月至2017年12月海南省人民医院收治的老年冠心病患者154例作为研究对象,按照随机数字表法随机分为对照组和观察组,每组77例。对照组采用常规西药治疗,观察组在此基础上加服复方丹参滴丸。比较治疗前后2组患者的血流变学、血脂、炎性反应递质和疗效。结果:观察组治疗有效率为92.21%,明显高于对照组治疗有效率79.22%,差异有统计学意义(P<0.05)。治疗后,2组总胆固醇(TC)、三酰甘油(TG)和低密度脂蛋白(LDL)水平均升高,差异有统计学意义(P<0.05),且观察组高于对照组,2组差异有统计学意义(P<0.05)。2组血流变学指标、高密度脂蛋白(HDL)、IL-6和TNF-α水平治疗后均降低(P<0.05),且观察组降低更明显,差异有统计学意义(P<0.05)。结论:复方丹参滴丸联合常规西药治疗冠心病患者,能够调节脂代谢,降低炎性反应,改善血流变学。  相似文献   
10.
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   
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