收费全文 | 251548篇 |
免费 | 18351篇 |
国内免费 | 1127篇 |
耳鼻咽喉 | 2787篇 |
儿科学 | 6496篇 |
妇产科学 | 4595篇 |
基础医学 | 32942篇 |
口腔科学 | 4559篇 |
临床医学 | 25329篇 |
内科学 | 53607篇 |
皮肤病学 | 3383篇 |
神经病学 | 24275篇 |
特种医学 | 8397篇 |
外国民族医学 | 11篇 |
外科学 | 38463篇 |
综合类 | 3456篇 |
一般理论 | 318篇 |
预防医学 | 21403篇 |
眼科学 | 6558篇 |
药学 | 16969篇 |
6篇 | |
中国医学 | 361篇 |
肿瘤学 | 17111篇 |
2023年 | 1338篇 |
2022年 | 2406篇 |
2021年 | 5436篇 |
2020年 | 3261篇 |
2019年 | 5300篇 |
2018年 | 5951篇 |
2017年 | 4470篇 |
2016年 | 4959篇 |
2015年 | 5830篇 |
2014年 | 8607篇 |
2013年 | 11794篇 |
2012年 | 18011篇 |
2011年 | 18900篇 |
2010年 | 10575篇 |
2009年 | 9427篇 |
2008年 | 16597篇 |
2007年 | 17452篇 |
2006年 | 17301篇 |
2005年 | 17276篇 |
2004年 | 16188篇 |
2003年 | 15038篇 |
2002年 | 14056篇 |
2001年 | 2104篇 |
2000年 | 1600篇 |
1999年 | 2322篇 |
1998年 | 3065篇 |
1997年 | 2561篇 |
1996年 | 2183篇 |
1995年 | 2096篇 |
1994年 | 1744篇 |
1993年 | 1571篇 |
1992年 | 1260篇 |
1991年 | 1151篇 |
1990年 | 1000篇 |
1989年 | 976篇 |
1988年 | 968篇 |
1987年 | 948篇 |
1986年 | 950篇 |
1985年 | 964篇 |
1984年 | 1217篇 |
1983年 | 1126篇 |
1982年 | 1365篇 |
1981年 | 1312篇 |
1980年 | 1145篇 |
1979年 | 705篇 |
1978年 | 747篇 |
1977年 | 637篇 |
1976年 | 584篇 |
1975年 | 471篇 |
1974年 | 473篇 |
Purpose
The purpose of this study was to evaluate trends in demographics and outcomes of pediatric breast cancer in a United States population-based cohort.Methods
The Surveillance, Epidemiology, and End Results (SEER) database was utilized to identify all pediatric patients with malignant breast tumors between 1973 and 2014. Analysis was performed using Stata Statistical Software version 13.1. Associations between categorical variables were made using X2 test. Log-rank test was used for univariate survival analysis. Kaplan–Meier analysis investigated five-year survival rates across several variables. Adjusted analysis was performed using a Cox Proportional-Hazards regression.Results
134 patients with breast malignancies were identified. Carcinoma was the most prevalent histology (48.5%), followed by fibroepithelial tumors (FETs) (35.1%), and sarcoma (14.2%). FETs were twice as common in black compared to nonblack patients (56.3% vs. 29.0%, p?<?0.01). Analyzing histology by stage revealed that 100% of FETs were early stage disease (p?<?0.0001). 46.7% of the tumors tested were ER/PR negative, more than twice as many compared to the published adult estimate of 20.0%. Unadjusted survival analysis revealed worse survival for patients with adenocarcinoma/sarcomas, advanced stage, and high grade disease, without a survival difference between races.Conclusion
Breast cancer remains a rare malignancy among pediatric patients. Although black patients were found to have more noncarcinomatous tumors with less advanced disease, this did not confer a survival advantage.Type of study
Retrospective cohort study.Level of evidence
Level III. 相似文献Background
The clinical experience of ceftaroline fosamil (CPT-F) therapy for Gram-positive infective endocarditis is reported from CAPTURE, a retrospective study conducted in the USA.Methods
Data, including patient demographics, medical history, risk factors, microbiological aetiology and clinical outcomes, were collected by review of patient charts between September 2013 and February 2015.Results
Patients (n=55) with Gram-positive endocarditis were treated with CPT-F. The most common risk factors were intravascular devices (43.6%), diabetes mellitus (40.0%) and injection drug use (38.2%). The most commonly isolated pathogens were meticillin-resistant Staphylococcus aureus (MRSA; 80%), meticillin-susceptible S. aureus (MSSA; 7.3%) and coagulase-negative staphylococci (7.3%). CPT-F was given as first-line therapy in 7.3% of patients and as second-line or later therapy in 92.7% of patients, and as monotherapy in 41.8% of patients and as concurrent therapy in 58.2% of patients. Clinical success was observed in 82.6% (19/23) of patients treated with CPT-F as monotherapy. In patients treated with CPT-F as first-line therapy or second-line or later therapy, 75.0% (3/4) and 70.6% (36/51) achieved success, respectively. Clinical success was observed in 77.3% (34/44) of patients with MRSA and 25% (1/4) of patients with MSSA. Two patients discontinued treatment with CPT-F due to an adverse event.Conclusions
CPT-F treatment was associated with a high rate of clinical success in patients with Gram-positive infective endocarditis, including those with risk factors and infections caused by MRSA. A high rate of clinical success was observed in patients treated with CPT-F used as first- line therapy or second-line or later therapy, or as monotherapy or in combination with other antibiotics. 相似文献Background
We have recently shown that human epididymis protein 4 (HE4) levels correlate with the severity of cystic fibrosis (CF) lung disease. However, there are no data on how HE4 levels alter in patients receiving CFTR modulating therapy.Methods
In this retrospective clinical study, 3 independent CF patient cohorts (US-American: 29, Australian: 12 and Irish: 19 cases) were enrolled carrying at least one Class III CFTR CF-causing mutation (p.Gly551Asp) and being treated with CFTR potentiator ivacaftor. Plasma HE4 was measured by immunoassay before treatment (baseline) and 1–6?months after commencement of ivacaftor, and were correlated with FEV1 (% predicted), sweat chloride, C-reactive protein (CRP) and body mass index (BMI).Results
After 1?month of therapy, HE4 levels were significantly lower than at baseline and remained decreased up to 6?months. A significant inverse correlation between absolute and delta values of HE4 and FEV1 (r?=??0.5376; P?<?.001 and r?=??0.3285; P?<?.001), was retrospectively observed in pooled groups, including an independent association of HE4 with FEV1 by multiple regression analysis (β?=??0.57, P?=?.019). Substantial area under the receiver operating characteristic curve (ROC-AUC) value was determined for HE4 when 7% mean change of FEV1 (0.722 [95% CI 0.581–0.863]; P?=?.029) were used as classifier, especially in the first 2?months of treatment (0.806 [95% CI 0.665–0.947]; P?<?.001).Conclusions
This study shows that plasma HE4 levels inversely correlate with lung function improvement in CF patients receiving ivacaftor. Overall, this potential biomarker may be of value for routine clinical and laboratory follow-up of CFTR modulating therapy. 相似文献Objective: To quantify spatiotemporal and kinematic BW characteristics in post-stroke community ambulators and compare their performance to controls.
Methods: Individuals post-stroke (n = 15, 60.1 ± 12.9 years, forward speed: 1.13 ± 0.23 m/s) and healthy adults (n = 12, 61.2 ± 16.2 years, forward speed: 1.40 ± 0.13 m/s) performed forward walking (FW) and BW during a single session. Step characteristics and peak lower extremity joint angles were extracted using 3D motion analysis and analyzed with mixed-method ANOVAs (group, walking condition).
Results: The stroke group demonstrated greater reductions in speed, step length and cadence and a greater increase in double-support time during BW compared to FW (p < .01). Compared to FW, the post-stroke group demonstrated greater reductions in hip extension and knee flexion during BW (p < .05). The control group demonstrated decreased plantarflexion and increased dorsiflexion during BW, but these increases were attenuated in the post-stroke group (p < .05).
Conclusions: Assessment of BW can unmask post-stroke walking impairments not detected during typical FW. BW impairments may contribute to the mobility difficulties reported by adults post-stroke. Therefore, BW should be assessed when determining readiness for home and community ambulation. 相似文献