全文获取类型
收费全文 | 925242篇 |
免费 | 77012篇 |
国内免费 | 5232篇 |
专业分类
耳鼻咽喉 | 13650篇 |
儿科学 | 25301篇 |
妇产科学 | 25891篇 |
基础医学 | 132747篇 |
口腔科学 | 26764篇 |
临床医学 | 82693篇 |
内科学 | 175034篇 |
皮肤病学 | 17995篇 |
神经病学 | 73673篇 |
特种医学 | 38504篇 |
外国民族医学 | 208篇 |
外科学 | 143502篇 |
综合类 | 32300篇 |
现状与发展 | 10篇 |
一般理论 | 267篇 |
预防医学 | 70343篇 |
眼科学 | 22472篇 |
药学 | 70999篇 |
43篇 | |
中国医学 | 4419篇 |
肿瘤学 | 50671篇 |
出版年
2021年 | 8382篇 |
2018年 | 9623篇 |
2016年 | 8798篇 |
2015年 | 10888篇 |
2014年 | 15013篇 |
2013年 | 20445篇 |
2012年 | 28476篇 |
2011年 | 29528篇 |
2010年 | 17588篇 |
2009年 | 16079篇 |
2008年 | 26463篇 |
2007年 | 28268篇 |
2006年 | 27837篇 |
2005年 | 27120篇 |
2004年 | 25894篇 |
2003年 | 24804篇 |
2002年 | 23694篇 |
2001年 | 36907篇 |
2000年 | 37539篇 |
1999年 | 31970篇 |
1998年 | 9856篇 |
1997年 | 9237篇 |
1996年 | 9021篇 |
1995年 | 8457篇 |
1994年 | 8093篇 |
1992年 | 26972篇 |
1991年 | 26320篇 |
1990年 | 25815篇 |
1989年 | 24844篇 |
1988年 | 23355篇 |
1987年 | 23001篇 |
1986年 | 21833篇 |
1985年 | 21182篇 |
1984年 | 16430篇 |
1983年 | 14043篇 |
1982年 | 8879篇 |
1981年 | 8226篇 |
1979年 | 16754篇 |
1978年 | 12120篇 |
1977年 | 10184篇 |
1976年 | 9332篇 |
1975年 | 10150篇 |
1974年 | 12646篇 |
1973年 | 12146篇 |
1972年 | 11540篇 |
1971年 | 10692篇 |
1970年 | 10223篇 |
1969年 | 9919篇 |
1968年 | 8906篇 |
1967年 | 8234篇 |
排序方式: 共有10000条查询结果,搜索用时 625 毫秒
51.
52.
53.
54.
【目的】探讨中药淫羊藿、巴戟天提取物(中药注射液喘可治的组成)对恒河猴单核衍生的巨噬细胞在未极化(M0)、M1极化条件下基因表达的影响,分析其可能的免疫调节的作用机制。【方法】采用密度梯度离心法分离中国恒河猴外周血单个核细胞(PBMCs),采用贴壁法纯化出单核细胞,并以粒细胞巨噬细胞集落刺激因子(GM-CSF)刺激5 d以使单核细胞分化成巨噬细胞;然后不加入极化因子(M0)或以干扰素γ(IFN-γ,继续培养2 d)诱导巨噬细胞极化为M1表型,同时分别加入淫羊藿、巴戟天提取物进行干预;然后提取m RNA并逆转录后,采用实时荧光定量PCR检测CCR5、CD4、CTLA-4、Fox P3、IDO、IL-10、TGF-β等基因表达量。【结果】与空白对照组比较,加入巴戟天提取物培养的M0巨噬细胞基因表达上调不明显;经淫羊藿提取物培养的M0巨噬细胞,CCR5基因表达量上调4.21倍,TGF-β上调7.66倍,Fox P3、IL-10轻度上调,而CD4、CTLA-4、IDO等基因表达改变倍数无明显变化。经巴戟天提取物刺激的M1型巨噬细胞,CTLA-4基因表达量上调3.22倍,Fox P3上调3.69倍,CCR5、CD4、IL-10、IDO基因改变倍数均无明显变化,TGF-β未测出;而由淫羊藿提取物刺激的M1型巨噬细胞,IL-10的表达量上调11.83倍,Fox P3上调4.55倍,IDO、CCR5、CD4、CTLA-4基因改变倍数无明显变化,TGF-β未测出。【结论】巴戟天和淫羊藿提取物培养能够上调M1型巨噬细胞IL-10、Fox P3、CTLA-4等抑炎基因表达,淫羊藿提取物能够上调M0巨噬细胞CCR5和TGF-β等基因表达,促进病原体清除和组织修复,从而发挥多效免疫调节作用。 相似文献
55.
Paul J. Devlin Brian W. McCrindle James K. Kirklin Eugene H. Blackstone William M. DeCampli Christopher A. Caldarone Ali Dodge-Khatami Pirooz Eghtesady James M. Meza Peter J. Gruber Kristine J. Guleserian Bahaaladin Alsoufi Linda M. Lambert James E. OBrien Erle H. Austin Jeffrey P. Jacobs Tara Karamlou 《The Journal of thoracic and cardiovascular surgery》2019,157(2):684-695.e8
Objective
Arch obstruction after the Norwood procedure is common and contributes to mortality. We determined the prevalence, associated factors, and practice variability of arch reintervention and assessed whether arch reintervention is associated with mortality.Methods
From 2005 to 2017, 593 neonates in the Congenital Heart Surgeons' Society Critical Left Heart Obstruction cohort underwent a Norwood procedure. Median follow-up was 3.7 years. Multivariable parametric models, including a modulated renewal analysis, were performed.Results
Of the 593 neonates, 146 (25%) underwent 218 reinterventions for arch obstruction after the Norwood procedure: catheter-based (n = 168) or surgical (n = 50) at a median age of 4.3 months (quartile 1-quartile 3, 2.6-5.7). Interdigitation of the distal aortic anastomosis was protective against arch reintervention. Development of ≥ moderate tricuspid valve regurgitation and right ventricular dysfunction at any point was associated with arch reintervention. Nonsignificant variables for arch reintervention included shunt type and preoperative aortic measurements. Surgical arch reintervention was protective against arch reintervention, but transcatheter reintervention was associated with increased reintervention. Arch reintervention was not associated with increased mortality. There was wide institutional variation in incidence of arch reintervention (range, 0-40 reinterventions per 100 years patient follow-up) and in preintervention gradient (range, 0-64 mm Hg).Conclusions
Interdigitation of the distal aortic anastomosis during the Norwood procedure decreased the risk of arch reintervention. Surgical arch reintervention is more definitive than transcatheter. Arch reintervention after the Norwood procedure is not associated with increased mortality. Serial surveillance for arch obstruction, integrated with changes in right ventricular function and tricuspid valve regurgitation, is recommended after the Norwood procedure to improve outcomes. 相似文献56.
To evaluate the anthropometric indexes in subjects with varicocele compared to controls and the incidence of varicocele in different body mass index (BMI) groups for the purpose of exploring the association between varicocele and anthropometric indexes. A comprehensive literature search was conducted by using PubMed, MEDLINE, EMBASE databases and Cochrane Library up to February 2019. A systematic review and meta‐analysis was conducted by STATA, and Newcastle–Ottawa Scale was utilised for assessing risk of bias. Ultimately, 13 articles containing seven case–control studies and six cross‐sectional studies with 1,385,630 subjects were involved in our study. Pooled results demonstrated that varicocele patients had a lower BMI (WMD = ?0.77, 95% CI = ?1.03 to ?0.51) and a higher height than nonvaricocele participants, especially in grade 3 varicocele patients. Subgroup analyses showed that normal BMI individuals had a higher risk of varicocele than obese or overweight individuals and a lower risk than underweight individuals. In conclusion, this study indicates that varicocele patients have a lower BMI and a higher height than nonvaricocele participants. Moreover, men with excess bodyweight have a lower incidence of varicocele compared to normal weight or underweight people. That is to say, high BMI and adiposity protect against varicocele and high BMI is associated with a decreased risk of varicocele. 相似文献
57.
58.
59.
60.