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   233305篇
  免费   20088篇
  国内免费   7571篇
耳鼻咽喉   1930篇
儿科学   4498篇
妇产科学   2427篇
基础医学   41065篇
口腔科学   4535篇
临床医学   20830篇
内科学   32578篇
皮肤病学   3678篇
神经病学   12268篇
特种医学   4380篇
外国民族医学   47篇
外科学   19423篇
综合类   34447篇
现状与发展   24篇
一般理论   25篇
预防医学   13513篇
眼科学   5113篇
药学   27331篇
  17篇
中国医学   10876篇
肿瘤学   21959篇
  2023年   3034篇
  2022年   4249篇
  2021年   7592篇
  2020年   7232篇
  2019年   8109篇
  2018年   8064篇
  2017年   7907篇
  2016年   7585篇
  2015年   8340篇
  2014年   12368篇
  2013年   14268篇
  2012年   12114篇
  2011年   14295篇
  2010年   12098篇
  2009年   12185篇
  2008年   11768篇
  2007年   12534篇
  2006年   11587篇
  2005年   10980篇
  2004年   9652篇
  2003年   8558篇
  2002年   6536篇
  2001年   6062篇
  2000年   5174篇
  1999年   4499篇
  1998年   3229篇
  1997年   2993篇
  1996年   2892篇
  1995年   3048篇
  1994年   2600篇
  1993年   2293篇
  1992年   1911篇
  1991年   1696篇
  1990年   1387篇
  1989年   1256篇
  1988年   1137篇
  1987年   909篇
  1986年   739篇
  1985年   1070篇
  1984年   1158篇
  1983年   737篇
  1982年   894篇
  1981年   745篇
  1980年   646篇
  1979年   540篇
  1978年   439篇
  1977年   357篇
  1976年   402篇
  1975年   258篇
  1974年   203篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
In this paper, we argue that understanding and addressing the problem of poor-quality medical products requires a more interdisciplinary approach than has been evident to date. While prospective studies based on rigorous standardized methodologies are the gold standard for measuring the prevalence of poor-quality medical products and understanding their distribution nationally and internationally, they should be complemented by social science research to unpack the complex set of social, economic, and governance factors that underlie these patterns. In the following sections, we discuss specific examples of prospective quality surveys and of social science studies, highlighting the value of cross-sector partnerships in driving high-quality, policy-relevant research in this area.  相似文献   
2.
《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   
3.
《Vaccine》2022,40(30):4038-4045
PurposeAs protection from COVID-19 following two doses of the BNT162b2 vaccine showed a time dependent waning, a third (booster) dose was administrated. This study aims to compare the antibody response following the third dose versus the second and to evaluate post-booster seroconversion.MethodsA prospective observational study conducted in Maccabi Healthcare Services. Serial SARS-CoV-2 Spike IgG tests, 1,2,3 and 6 months following the second vaccine dose and one month following the third were obtained. Neutralizing antibody levels were measured in a subset of participants. Per individual SARS-CoV-2 Spike IgG titer ratios were calculated one month after the booster administration compared to titers one month following the second dose and prior to booster.ResultsAmong 110 participants, 56 (51%) were women. Mean age was 61.7 ± 1.9 years and 66 (60%) were immunocompromised. One month after third dose, IgG titers were induced 7.83 (95 %CI 5.25–11.67) folds and 2.40 (95 %CI 1.90–3.03) folds compared to one month after the second, in the immunocompromised and immunocompetent groups, respectively. Of the 17 immunocompromised participants who were seronegative after the second dose, 4 (24%) became seropositive following the third. Comparing the titers prior to the third dose, an increase of 50.7 (95 %CI 32.5–79.1) fold in the immunocompromised group and 25.7 (95 %CI 19.1–34.7) fold in and immunocompetent group, was observed.ConclusionA third BNT162b2 vaccine elicited robust humoral response, superior to the response observed following the second, among immunocompetent and immunocompromised individuals.  相似文献   
4.
5.
6.
7.
地鳖中的纤溶活性蛋白是从地鳖中提取的具有抗栓及抗肿瘤作用的有效成分,其口服易被上消化道酶分解从而限制了应用。采用恒流泵滴制法开发地鳖纤溶活性蛋白时间/pH依赖口服结肠靶向微囊(EnpolypHaga fibrinolytic protein oral colon targeting microcapsules, CTM-EFP)。采用单因素实验和正交实验相结合的方法寻找到包封率为60.17 % ± 2.72 %、载药量为15.50 % ± 0.44 % 的最佳配方。扫描电子显微镜(SEM)显示微囊呈球形、表面光滑,在人工肠液中24 h的累积释放度为99.53 % ± 0.69 %,在人工胃液中24 h累积释放度为7.43 ± 1.04 %,通过时间/pH依赖达到结肠靶向作用。CTM-EFP在人工肠液中的体外释放曲线符合Korsmeyer方程,提示地鳖纤溶活性蛋白(EnpolypHaga fibrinolytic protein, EFP)是通过扩散和侵蚀机制结合释放的。CTM-EFP为EFP的口服给药提供了一种新的剂型,为EFP应用于临床提供参考。  相似文献   
8.
9.
胶质淋巴系统是一个主要由星形胶质细胞水通道蛋白4介导的依靠动脉、静脉周围血管间隙的脑脊液-脑组织液交换流动的系统,是阿尔茨海默病、脑卒中、帕金森病、失眠、抑郁症等脑病的共同特征,是一条新的脑代谢途径,可以清除包括β-淀粉样蛋白、乳酸在内的代谢产物。本文综合分析了全球有关胶质淋巴系统在脑部疾病的研究,得出:胶质淋巴系统可能为神经退行性疾病等发病机制和诊治策略研究带来新视角;胶质淋巴系统有望为一些脑部疾病诊断提供新的有效证据;胶质淋巴系统可能是脑部疾病治疗给药方式的新途径。  相似文献   
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