全文获取类型
收费全文 | 433433篇 |
免费 | 29352篇 |
国内免费 | 4474篇 |
专业分类
耳鼻咽喉 | 5955篇 |
儿科学 | 9274篇 |
妇产科学 | 12001篇 |
基础医学 | 59996篇 |
口腔科学 | 12780篇 |
临床医学 | 36107篇 |
内科学 | 88222篇 |
皮肤病学 | 9579篇 |
神经病学 | 30531篇 |
特种医学 | 16225篇 |
外国民族医学 | 88篇 |
外科学 | 68101篇 |
综合类 | 13913篇 |
现状与发展 | 8篇 |
一般理论 | 75篇 |
预防医学 | 20413篇 |
眼科学 | 10711篇 |
药学 | 35778篇 |
20篇 | |
中国医学 | 3766篇 |
肿瘤学 | 33716篇 |
出版年
2021年 | 4187篇 |
2020年 | 2879篇 |
2019年 | 4264篇 |
2018年 | 6391篇 |
2017年 | 4848篇 |
2016年 | 4992篇 |
2015年 | 6220篇 |
2014年 | 8428篇 |
2013年 | 10577篇 |
2012年 | 14599篇 |
2011年 | 14658篇 |
2010年 | 9023篇 |
2009年 | 8342篇 |
2008年 | 12811篇 |
2007年 | 13622篇 |
2006年 | 13397篇 |
2005年 | 12207篇 |
2004年 | 11442篇 |
2003年 | 11061篇 |
2002年 | 10382篇 |
2001年 | 29500篇 |
2000年 | 29785篇 |
1999年 | 24477篇 |
1998年 | 5459篇 |
1997年 | 4443篇 |
1996年 | 4020篇 |
1995年 | 3803篇 |
1994年 | 3397篇 |
1993年 | 3042篇 |
1992年 | 16524篇 |
1991年 | 15195篇 |
1990年 | 14521篇 |
1989年 | 14300篇 |
1988年 | 12875篇 |
1987年 | 12383篇 |
1986年 | 11369篇 |
1985年 | 10560篇 |
1984年 | 7099篇 |
1983年 | 5766篇 |
1982年 | 2816篇 |
1979年 | 5650篇 |
1978年 | 3477篇 |
1977年 | 3047篇 |
1975年 | 2720篇 |
1974年 | 3145篇 |
1973年 | 2932篇 |
1972年 | 2892篇 |
1971年 | 2836篇 |
1970年 | 2554篇 |
1969年 | 2573篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
Chang Patrick K. C. Prestidge Clive A. Bremmell Kristen E. 《Pharmaceutical research》2022,39(6):1151-1163
Pharmaceutical Research - Cationic polymers have many advantages as vectors for mediated cellular entry and delivery of siRNA. However, toxicity related to their cationic charge has compromised... 相似文献
23.
24.
Comprehensive evidence regarding the treatment of non-anaemic iron deficiency in patients undergoing valvular heart surgery is lacking. This study aimed to investigate the association between non-anaemic iron deficiency and postoperative outcomes in these patients. We retrospectively analysed 321 patients of which 180 (56%) had iron deficiency (defined as serum ferritin < 100 ng.ml-1 or < 300 ng.ml-1 with transferrin saturation < 20%). While the iron-deficient group had lower pre-operative haemoglobin levels than the non-iron deficient group (median (IQR [range]) 134 (127–141 [120–172]) g.l-1, 143 (133–150 [120–179]) g.l-1, p = 0.001), there was no between-group difference in allogeneic red blood cell transfusion. Median (IQR [range]) days alive and out of hospital at postoperative day 90 was 1 day shorter in the iron-deficient group (80 (77–82 [9–85]) days vs. 81 (79–83 [0–85]) days, p = 0.026). In multivariable analysis, only cardiopulmonary bypass duration (p = 0.032) and intra-operative allogeneic red blood cell transfusion (p = 0.011) were significantly associated with reduced days alive and out of hospital at postoperative day 90. Iron deficiency did not exert any adverse influence on secondary outcomes except length of hospital stay. Our findings indicate that non-anaemic iron deficiency alone is not associated with adverse effects in patients undergoing valvular heart surgery when it does not translate into an increased risk of allogeneic transfusion. 相似文献
25.
26.
27.
Michael T Milano Veronica L S Chiang Scott G Soltys Tony J C Wang Simon S Lo Alexandria Brackett Seema Nagpal Samuel Chao Amit K Garg Siavash Jabbari Lia M Halasz Melanie Hayden Gephart Jonathan P S Knisely Arjun Sahgal Eric L Chang 《Neuro-oncology》2020,22(12):1728
BackgroundThe American Radium Society (ARS) Appropriate Use Criteria brain malignancies panel systematically reviewed (PRISMA [Preferred Reporting Items for Systematic Reviews and Meta-Analyses]) published literature on neurocognitive outcomes after stereotactic radiosurgery (SRS) for patients with multiple brain metastases (BM) to generate consensus guidelines.MethodsThe panel developed 4 key questions (KQs) to guide systematic review. From 11 614 original articles, 12 were selected. The panel developed model cases addressing KQs and potentially controversial scenarios not addressed in the systematic review (which might inform future ARS projects). Based upon quality of evidence, the panel confidentially voted on treatment options using a 9-point scale of appropriateness.ResultsThe panel agreed that SRS alone is usually appropriate for those with good performance status and 2–10 asymptomatic BM, and usually not appropriate for >20 BM. For 11–15 and 16–20 BM there was (between 2 case variants) agreement that SRS alone may be appropriate or disagreement on the appropriateness of SRS alone. There was no scenario (among 6 case variants) in which conventional whole-brain radiotherapy (WBRT) was considered usually appropriate by most panelists. There were several areas of disagreement, including: hippocampal sparing WBRT for 2–4 asymptomatic BM; WBRT for resected BM amenable to SRS; fractionated versus single-fraction SRS for resected BM, larger targets, and/or brainstem metastases; optimal treatment (WBRT, hippocampal sparing WBRT, SRS alone to all or select lesions) for patients with progressive extracranial disease, poor performance status, and no systemic options.ConclusionsFor patients with 2–10 BM, SRS alone is an appropriate treatment option for well-selected patients with good performance status. Future study is needed for those scenarios in which there was disagreement among panelists. 相似文献
28.
Jie Ren Ying-Mu Tong Rui-Xia Cui Zi Wang Qing-Lin Li Wei Liu Kai Qu Jing-Yao Zhang Chang Liu Yong Wan 《World journal of gastrointestinal oncology》2020,12(12):1394-1406
BACKGROUNDDue to the special clinical features and biologic characteristics of adolescent and young adult (AYA) cancers, AYA cancers are different from cancers in children and elderly individuals. However, there are few reports on AYA hepatocellular carcinoma (HCC).AIMTo investigate the overall survival (OS) of AYA (15-39 years) and elderly (40-74 years) patients with HCC.METHODSThe data of all the HCC cases were extracted from the Surveillance, Epidemiology, and End Results database from 2004 to 2015 and were then divided into two groups based on age: AYA group (15-39 years) and older group (40-74 years). Kaplan-Meier curves and log-rank tests were used to compare the OS of the two groups. Propensity score matching (PSM) was employed to analyze the OS difference between the two groups. The Cox proportional hazards regression model was used to perform multivariate analysis to explore the risk factors for OS of HCC patients.RESULTSCompared to elderly cancer patients, AYA patients with HCC had a worse Surveillance, Epidemiology, and End Results stage, including the distant stage (22.1% vs 15.4%, P < 0.001), and a more advanced American Joint Committee on Cancer (AJCC) stage, including AJCC III and IV (49.2% vs 38.3%, P < 0.001), and were more likely to receive surgery (64.5% vs 47.5%, P < 0.001). Before PSM, the AYA group had a longer survival in months (median: 20.00, interquartile range [IQR]: 5.00-62.50) than the older group (median: 15.00, IQR: 4.00-40.00) (P < 0.001). After PSM, the AYA group still had a longer survival in months (median: 21.00, IQR: 5.00-64.50) than the older group (median: 18.00, IQR: 6.00-53.00) (P < 0.001). The Cox proportional hazards regression model showed that advanced age (hazard ratio [HR] = 1.405, 95%CI: 1.218-1.621, P < 0.001) was a risk factor for OS of HCC patients. In the subgroup analysis, the Cox proportional hazards regression model showed that in AJCC I/II HCC patients, advanced age (HR = 1.749, 95%CI: 1.352-2.263, P < 0.001) was a risk factor for OS, while it was not a risk factor in AJCC III/IV HCC patients (HR = 1.186, 95%CI: 0.997-1.410, P = 0.054) before PSM. After PSM, advanced age (HR = 1.891, 95%CI: 1.356-2.637, P < 0.001) was still a risk factor for OS in AJCC I/II HCC patients, but was not a risk factor for OS in AJCC III/IV HCC patients (HR = 1.192, 95%CI: 0.934-1.521, P = 0.157) after PSM.CONCLUSIONAYA patients with HCC have different clinical characteristics from older adults. In different AJCC stages, the two groups of patients have different OS: In AJCC I/II HCC patients, advanced age is a risk factor for OS, but it is not a risk factor for OS in the AJCC III/IV HCC patient group. 相似文献
29.
目的建立保健食品原料评价体系(Functional Food Crude Materials Evaluation System,FUFMES),为保健食品原料目录排名提供科学依据与技术保障。方法首先,利用文献调研和多轮专家访谈方法筛选FUFMES的指标并确定其层级关系;第二,使用层次分析法(Analytic Hierarchy Process,AHP)计算指标权重,具体方法是依据专家打分构建判断矩阵,利用R语言进行一致性检验与最大特征根检验,得出各级指标权重;第三,使用极值法计算原料的单个指标值;第四,利用线性加权综合法得到每种原料的评价指数并据此进行排名;最后,将获得的分析结果与专家评价结果进行比较。结果 FUFMES包括6个一级指标、39个二级指标、11个三级指标。利用FUFMES对9种保健食品原料进行评价,获得的评价指数依次是:西洋参(0.49)、人参(0.48)、银杏叶(0.21)、灵芝孢子粉(0.08)、鱼油(0.06)、螺旋藻(0.03)、辅酶Q10(0.02)、褪黑素(0.01)、大蒜油(-0.03)。基于该评价指数的排名结果与专家评价结果显示了较高一致性。结论构建了科学、完整的FUFMES,FUFMES将成为保健食品原料目录评价与排名的有力工具,为推进保健食品原料备案制提供科学依据与技术保障。 相似文献
30.
Yi Su Jean W. Woo Timothy C.Y. Kwok 《Journal of the American Medical Directors Association》2019,20(1):83-89