全文获取类型
收费全文 | 94302篇 |
免费 | 7100篇 |
国内免费 | 2339篇 |
专业分类
耳鼻咽喉 | 107篇 |
儿科学 | 3205篇 |
妇产科学 | 1182篇 |
基础医学 | 5958篇 |
口腔科学 | 636篇 |
临床医学 | 12861篇 |
内科学 | 29299篇 |
皮肤病学 | 212篇 |
神经病学 | 1406篇 |
特种医学 | 2340篇 |
外国民族医学 | 1篇 |
外科学 | 10342篇 |
综合类 | 17109篇 |
现状与发展 | 6篇 |
一般理论 | 3篇 |
预防医学 | 4258篇 |
眼科学 | 112篇 |
药学 | 8643篇 |
98篇 | |
中国医学 | 5291篇 |
肿瘤学 | 672篇 |
出版年
2024年 | 66篇 |
2023年 | 1372篇 |
2022年 | 1925篇 |
2021年 | 3427篇 |
2020年 | 3763篇 |
2019年 | 3260篇 |
2018年 | 3151篇 |
2017年 | 3025篇 |
2016年 | 2982篇 |
2015年 | 3097篇 |
2014年 | 6529篇 |
2013年 | 6837篇 |
2012年 | 5261篇 |
2011年 | 5924篇 |
2010年 | 4734篇 |
2009年 | 4603篇 |
2008年 | 4585篇 |
2007年 | 4695篇 |
2006年 | 4264篇 |
2005年 | 3954篇 |
2004年 | 3165篇 |
2003年 | 2741篇 |
2002年 | 2360篇 |
2001年 | 2153篇 |
2000年 | 1731篇 |
1999年 | 1639篇 |
1998年 | 1342篇 |
1997年 | 1277篇 |
1996年 | 1063篇 |
1995年 | 1055篇 |
1994年 | 1048篇 |
1993年 | 753篇 |
1992年 | 723篇 |
1991年 | 685篇 |
1990年 | 540篇 |
1989年 | 524篇 |
1988年 | 468篇 |
1987年 | 399篇 |
1986年 | 354篇 |
1985年 | 393篇 |
1984年 | 341篇 |
1983年 | 202篇 |
1982年 | 233篇 |
1981年 | 215篇 |
1980年 | 177篇 |
1979年 | 157篇 |
1978年 | 137篇 |
1977年 | 107篇 |
1976年 | 102篇 |
1975年 | 63篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
《Nefrología : publicación oficial de la Sociedad Espa?ola Nefrologia》2022,42(2):145-162
Renal sodium and water retention with resulting extracellular volume expansion and redistribution are hallmark features of heart failure syndromes. However, congestion assessment, monitoring, and treatment represent a real challenge in daily clinical practice. This document reviewed historical and contemporary evidence of available methods for determining volume status and discuss pharmacological aspects and pathophysiological principles that underlie diuretic use. 相似文献
23.
24.
25.
26.
27.
ObjectiveTo investigate the feasibility of transnasal heated humidified high flow nasal cannula oxygen therapy (HFNC) in the treatment of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) with respiratory failure in elderly patients. MethodsA total of 176 elderly patients with AECOPD complicated with respiratory failure who were hospitalized at Peking University Shougang Hospital from December 2016 to January 2022 were enrolled, including 82 patients in an HFNC group and 94 patients in an NPPV group. After treatment, pulse oxygen saturation (SPO2), arterial partial pressure of carbon dioxide (PaCO2), oxygenation index (OI), respiratory rate (RR), heart rate (HR), mean arterial pressure (MAP), comfort score, discharge rate, rate of endotracheal intubation, rate of transfer to intensive care unit (ICU), and mortality were compared between the two groups. The independent sample t-test was used for comparison between the two groups. Statistical data are expressed in percentage or number of cases and the χ2 test was used for their comparisons. ResultsThe SPO2 values at 30 min, 1 h, and 6 h were significantly higher in the HFNC group than in the NPPV group (t=-2.049,-2.618, and -3.314, P=0.043, 0.010, and 0.001, respectively). SPO2 before discharge was significantly lower than that of the NPPV group (t=2.162, P=0.033), but OI at each time point and before discharge had no statistical significance (P>0.05). MAP at 6 h was significantly higher in the HFNC group than in the NPPV group (t=-2.209, P=0.029), but within the normal range. HRs at 2 h and 3 h in the HFNC group were significantly higher than those of the NPPV group (t=-2.199 and -2.336, P=0.030 and 0.021, respectively). There were no significant differences in RR, HR, or MAP between the two groups at other time points and before discharge (P>0.05). There was no significant difference in PaCO2 between the two groups (P>0.05). Comfort score in the HFNC group was significantly higher than that of the NPPV group (t=-46.807, P<0.001). There were no significant differences in discharge rate, ICU transfer rate, endotracheal intubation rate, and mortality between the two groups (P>0.05). ConclusionHFNC is as effective as NPPV in treating elderly patients with AECOPD complicated with type Ⅰ or mild type Ⅱ respiratory failure, and HFNC is more comfortable than NPPV. 相似文献
28.
《The Journal of thoracic and cardiovascular surgery》2023,165(2):460-468.e2
ObjectivesDonor-specific cell-free DNA shows promise as a noninvasive marker for allograft rejection, but as yet has not been validated in both adult and pediatric recipients. The study objective was to validate donor fraction cell-free DNA as a noninvasive test to assess for risk of acute cellular rejection and antibody-mediated rejection after heart transplantation in pediatric and adult recipients.MethodsPediatric and adult heart transplant recipients were enrolled from 7 participating sites and followed for 12 months or more with plasma samples collected immediately before all endomyocardial biopsies. Donor fraction cell-free DNA was extracted, and quantitative genotyping was performed. Blinded donor fraction cell-free DNA and clinical data were analyzed and compared with a previously determined threshold of 0.14%. Sensitivity, specificity, negative predictive value, positive predictive value, and receiver operating characteristic curves were calculated.ResultsA total of 987 samples from 144 subjects were collected. After applying predefined clinical and technical exclusions, 745 samples from 130 subjects produced 54 rejection samples associated with the composite outcome of acute cellular rejection grade 2R or greater and pathologic antibody-mediated rejection 2 or greater and 323 healthy samples. For all participants, donor fraction cell-free DNA at a threshold of 0.14% had a sensitivity of 67%, a specificity of 79%, a positive predictive value of 34%, and a negative predictive value of 94% with an area under the curve of 0.78 for detecting rejection. When analyzed independently, these results held true for both pediatric and adult cohorts at the same threshold of 0.14% (negative predictive value 92% and 95%, respectively).ConclusionsDonor fraction cell-free DNA at a threshold of 0.14% can be used to assess for risk of rejection after heart transplantation in both pediatric and adult patients with excellent negative predictive value. 相似文献
29.
《The Medical clinics of North America》2022,106(3):545-555
30.
《The Journal of thoracic and cardiovascular surgery》2023,165(1):94-103.e24
ObjectiveNew-onset postoperative atrial fibrillation (POAF) after cardiac surgery is common, with rates up to 60%. POAF has been associated with early and late stroke, but its association with other cardiovascular outcomes is less known. The objective was to perform a meta-analysis of the studies reporting the association of POAF with perioperative and long-term outcomes in patients with cardiac surgery.MethodsWe performed a systematic review and a meta-analysis of studies that presented outcomes for cardiac surgery on the basis of the presence or absence of POAF. MEDLINE, EMBASE, and the Cochrane Library were assessed; 57 studies (246,340 patients) were selected. Perioperative mortality was the primary outcome. Inverse variance method and random model were performed. Leave-one-out analysis, subgroup analyses, and metaregression were conducted.ResultsPOAF was associated with perioperative mortality (odds ratio [OR], 1.92; 95% confidence interval [CI], 1.58-2.33), perioperative stroke (OR, 2.17; 95% CI, 1.90-2.49), perioperative myocardial infarction (OR, 1.28; 95% CI, 1.06-1.54), perioperative acute renal failure (OR, 2.74; 95% CI, 2.42-3.11), hospital (standardized mean difference, 0.80; 95% CI, 0.53-1.07) and intensive care unit stay (standardized mean difference, 0.55; 95% CI, 0.24-0.86), long-term mortality (incidence rate ratio [IRR], 1.54; 95% CI, 1.40-1.69), long-term stroke (IRR, 1.33; 95% CI, 1.21-1.46), and longstanding persistent atrial fibrillation (IRR, 4.73; 95% CI, 3.36-6.66).ConclusionsThe results suggest that POAF after cardiac surgery is associated with an increased occurrence of most short- and long-term cardiovascular adverse events. However, the causality of this association remains to be established. 相似文献