全文获取类型
收费全文 | 17385篇 |
免费 | 1466篇 |
国内免费 | 79篇 |
专业分类
耳鼻咽喉 | 315篇 |
儿科学 | 330篇 |
妇产科学 | 300篇 |
基础医学 | 2455篇 |
口腔科学 | 336篇 |
临床医学 | 1736篇 |
内科学 | 4153篇 |
皮肤病学 | 449篇 |
神经病学 | 1776篇 |
特种医学 | 1002篇 |
外国民族医学 | 3篇 |
外科学 | 2285篇 |
综合类 | 209篇 |
一般理论 | 8篇 |
预防医学 | 1161篇 |
眼科学 | 138篇 |
药学 | 1171篇 |
中国医学 | 13篇 |
肿瘤学 | 1090篇 |
出版年
2022年 | 138篇 |
2021年 | 300篇 |
2020年 | 157篇 |
2019年 | 278篇 |
2018年 | 336篇 |
2017年 | 268篇 |
2016年 | 348篇 |
2015年 | 449篇 |
2014年 | 518篇 |
2013年 | 662篇 |
2012年 | 1093篇 |
2011年 | 1125篇 |
2010年 | 627篇 |
2009年 | 608篇 |
2008年 | 1055篇 |
2007年 | 1146篇 |
2006年 | 1052篇 |
2005年 | 1083篇 |
2004年 | 988篇 |
2003年 | 984篇 |
2002年 | 883篇 |
2001年 | 342篇 |
2000年 | 309篇 |
1999年 | 305篇 |
1998年 | 199篇 |
1997年 | 222篇 |
1996年 | 189篇 |
1995年 | 150篇 |
1994年 | 150篇 |
1993年 | 134篇 |
1992年 | 178篇 |
1991年 | 188篇 |
1990年 | 177篇 |
1989年 | 159篇 |
1988年 | 130篇 |
1987年 | 153篇 |
1986年 | 131篇 |
1985年 | 131篇 |
1984年 | 118篇 |
1983年 | 103篇 |
1982年 | 113篇 |
1981年 | 85篇 |
1980年 | 84篇 |
1979年 | 87篇 |
1977年 | 70篇 |
1975年 | 74篇 |
1974年 | 75篇 |
1972年 | 68篇 |
1971年 | 61篇 |
1969年 | 64篇 |
排序方式: 共有10000条查询结果,搜索用时 22 毫秒
221.
222.
223.
The ability of various phenylalkylamines to inhibit the binding of [3H]tryptamine to rat frontal/parietal cortical membranes was examined in vitro. Affinity for [3H]tryptamine binding sites improved as the alkyl side chain was extended to include four carbons or when a methoxy group was added at the para position of the ring. One compound, p-methoxyphenylpropylamine (IC50 = 3.6 nM), was as potent as unlabelled tryptamine as a displacing agent. Based on the unique structure-activity relationship obtained, it appears that [3H]tryptamine binding sites do not mediate the actions of phenethylamines on serotonin uptake or release. 相似文献
224.
Juliane Kager Jochen Schneider Sebastian Rasch Peter Herhaus Mareike Verbeek Carolin Mogler Albert Heim Gert Frsner Dieter Hoffmann Roland M. Schmid Tobias Lahmer 《Viruses》2022,14(7)
Human adenovirus (HAdV) can often lead to fulminant hepatitis in immunocompromised patients, mostly after reactivation of HAdV. Different risk factors, e.g., transplantation and chemotherapy, increase the risk of developing a HAdV hepatitis. We retrospectively analyzed three patients who showed the characteristics of a HAdV hepatitis observed in disseminated disease. In addition to PCR, diagnosis could be proven by pathology, CT scan, and markedly elevated transaminases. All patients had a hemato-oncologic underlying disease. Two had received a stem-cell transplant, and one was under chemotherapy including rituximab. Despite therapy with cidofovir, all patients died. As the incidence of HAdV hepatitis is low, diagnosis may be easily overlooked. No treatment approaches have yet been established. HAdV hepatitis should be considered as a differential diagnosis, especially when risk factors are present. To avoid dissemination, treatment should be initiated as soon as possible. 相似文献
225.
Anemia and blood transfusion in critically ill patients 总被引:31,自引:1,他引:31
Vincent JL Baron JF Reinhart K Gattinoni L Thijs L Webb A Meier-Hellmann A Nollet G Peres-Bota D;ABC 《JAMA》2002,288(12):1499-1507
Context Anemia is a common problem in critically ill patients admitted to intensive care units (ICUs), but the consequences of anemia on morbidity and mortality in the critically ill is poorly defined. Objectives To prospectively define the incidence of anemia and use of red blood cell (RBC) transfusions in critically ill patients and to explore the potential benefits and risks associated with transfusion in the ICU. Design Prospective observational study conducted November 1999, with 2 components: a blood sampling study and an anemia and blood transfusion study. Setting and Patients The blood sampling study included 1136 patients from 145 western European ICUs, and the anemia and blood transfusion study included 3534 patients from 146 western European ICUs. Patients were followed up for 28 days or until hospital discharge, interinstitutional transfer, or death. Main Outcome Measures Frequency of blood drawing and associated volume of blood drawn, collected over a 24-hour period; hemoglobin levels, transfusion rate, organ dysfunction (assessed using the Sequential Organ Failure Assessment score), and mortality, collected throughout a 2-week period. Results The mean (SD) volume per blood draw was 10.3 (6.6) mL, with an average total volume of 41.1 (39.7) mL during the 24-hour period. There was a positive correlation between organ dysfunction and the number of blood draws (r = 0.34; P<.001) and total volume drawn (r = 0.28; P<.001). The mean hemoglobin concentration at ICU admission was 11.3 (2.3) g/dL, with 29% (963/3295) having a concentration of less than 10 g/dL. The transfusion rate during the ICU period was 37.0% (1307/3534). Older patients and those with a longer ICU length of stay were more commonly transfused. Both ICU and overall mortality rates were significantly higher in patients who had vs had not received a transfusion (ICU rates: 18.5% vs 10.1%, respectively; 2 = 50.1; P<.001; overall rates: 29.0% vs 14.9%, respectively; 2 = 88.1; P<.001). For similar degrees of organ dysfunction, patients who had a transfusion had a higher mortality rate. For matched patients in the propensity analysis, the 28-day mortality was 22.7% among patients with transfusions and 17.1% among those without (P = .02); the Kaplan-Meier log-rank test confirmed this difference. Conclusions This multicenter observational study reveals the common occurrence of anemia and the large use of blood transfusion in critically ill patients. Additionally, this epidemiologic study provides evidence of an association between transfusions and diminished organ function as well as between transfusions and mortality. 相似文献
226.
Nicolas von Landenberg Atiqullah Aziz Friedrich C. von Rundstedt Jakub Dobruch Luis A. Kluth Andrea Necchi Aidan Noon Michael Rink Kees Hendricksen Karel P.J. Decaestecker Roland Seiler Cédric Poyet Harun Fajkovic Shahrokh F. Shariat Evanguelos. Xylinas Florian Roghmann 《Urologic oncology》2018,36(5):238.e19-238.e27
Objective
To determine conditional recurrence-free survival (RFS) and progression-free survival (PFS) and improve decision-making toward surveillance protocols and scheduling. Furthermore, evaluating the evolution of predictors for disease recurrence over time, because TaG1 non–muscle-invasive bladder cancer harbors a risk of disease recurrence and progression.Material and methods
The retrospective multicenter design study includes 1,245 TaG1 bladder cancer patients with median follow-up of 62.7 (interquartile range: 34.3–91.1) months. Conditional RFS and PFS estimates were calculated using the Kaplan-Meier method. Multivariable Cox regression model was calculated proportional for the prediction of recurrence and progression (covariables: age, tumor size, multiple tumors, prior recurrence, and immediate postoperative instillation of chemotherapy).Results
After 3 months without event, the conditional RFS and PFS (to ≥pT2) rates for 5 additional years without event were 57.5% and 93.4%, respectively. Given a 1-, 2-, 3-, and 5-year survival, the conditional RFS rates for 5 additional years without event improved by +9.8 (67.3%), +5.2 (72.5%), +6.5 (79.0%), +2.0 (81.0%), and +1.0% (82.0%), respectively. In contrast, the 5-year conditional PFS rates were more or less stable with 94.3% after 1 year to 94.1% after 5 years. Multivariable analyses showed decreasing impact of risk parameters on RFS estimates over time. Based on these findings, we suggest a risk stratification to individualize follow-up for intermediate risk TaG1. Main limitation was the retrospective design.Conclusions
Conditional-survival analyses demonstrates that the patient risk profile changes over time. RFS rates rise with increasing survival whereas PFS rates were stable. The impact of prognostic features decreases over time. Our findings can be used for patient counseling and planning of personalized follow-up. 相似文献227.
Martin Lacher Guido Fitze Sebastian Schroepf Peter Lohse Antje Ballauff Jan Goedeke Roland Kappler 《Journal of pediatric surgery》2010,45(9):1826-1831
Backgroud/Purpose
Hirschsprung-associated enterocolitis (HAEC) represents a cause for significant pre- and postoperative morbidity and mortality in Hirschsprung disease (HD). Although multiple studies on HAEC have been performed and several mechanisms have been presumed, the pathogenesis of this condition remains unclear. As changes in colonic mucosal defense are key factors suggested in both Crohn's disease (CD) and HAEC pathogenesis, the aim of the current study was to investigate genetic alterations in the most important susceptibility gene for Crohn's enterocolitis (NOD2) to see whether carriers of polymorphisms within the NOD2 gene are predisposed to the development of HAEC.Methods
Genotyping for the NOD2 variants in exon 4 (p.Arg702Trp [rs2066844]), exon 8 (p.Gly908Arg [rs2066845]), and exon 11 (p.1007fs [rs2066847]) was performed in 52 white children with HD (41 boys, 11 girls), 152 healthy controls, and 152 children with CD (onset of disease <17 years; mean, 11.8 years). Seventeen patients with HD (32.7%) were carriers of a RET germline mutation, 35 children (67.3%) had short segment disease, and 17 (32.7%) had long segment disease.Results
Ten children (19.2%) with HD were heterozygous carriers of at least one NOD2 variant vs 17 (11.2%) in the healthy control group and 69 (45.4%) in the CD cohort. Hirschsprung-associated enterocolitis was observed in 7 children (13.5%), with 4 having short segment HD and 3 with long segment HD; but none of them were carriers of NOD2 variants.Conclusion
Our study shows that NOD2 variants described to be causatively associated with CD do not predispose to the development of HAEC. As data on the molecular basis of HAEC are limited, the distinct mechanisms involved in the pathogenesis of this complication remain unclear. 相似文献228.
229.
230.