全文获取类型
| 收费全文 | 3258308篇 |
| 免费 | 226036篇 |
| 国内免费 | 8441篇 |
专业分类
| 耳鼻咽喉 | 44809篇 |
| 儿科学 | 107925篇 |
| 妇产科学 | 90280篇 |
| 基础医学 | 458321篇 |
| 口腔科学 | 89593篇 |
| 临床医学 | 296241篇 |
| 内科学 | 633505篇 |
| 皮肤病学 | 78031篇 |
| 神经病学 | 263620篇 |
| 特种医学 | 125664篇 |
| 外国民族医学 | 918篇 |
| 外科学 | 485991篇 |
| 综合类 | 65440篇 |
| 现状与发展 | 6篇 |
| 一般理论 | 1175篇 |
| 预防医学 | 246006篇 |
| 眼科学 | 73744篇 |
| 药学 | 243400篇 |
| 13篇 | |
| 中国医学 | 7089篇 |
| 肿瘤学 | 181014篇 |
出版年
| 2019年 | 25497篇 |
| 2018年 | 36035篇 |
| 2017年 | 27891篇 |
| 2016年 | 32224篇 |
| 2015年 | 36161篇 |
| 2014年 | 49638篇 |
| 2013年 | 74244篇 |
| 2012年 | 99049篇 |
| 2011年 | 104718篇 |
| 2010年 | 63006篇 |
| 2009年 | 60175篇 |
| 2008年 | 97599篇 |
| 2007年 | 103839篇 |
| 2006年 | 105704篇 |
| 2005年 | 101322篇 |
| 2004年 | 97355篇 |
| 2003年 | 93915篇 |
| 2002年 | 90684篇 |
| 2001年 | 159347篇 |
| 2000年 | 163401篇 |
| 1999年 | 137515篇 |
| 1998年 | 38864篇 |
| 1997年 | 34494篇 |
| 1996年 | 34689篇 |
| 1995年 | 33512篇 |
| 1994年 | 30534篇 |
| 1993年 | 28642篇 |
| 1992年 | 106378篇 |
| 1991年 | 102417篇 |
| 1990年 | 99590篇 |
| 1989年 | 96347篇 |
| 1988年 | 88010篇 |
| 1987年 | 85998篇 |
| 1986年 | 80894篇 |
| 1985年 | 76970篇 |
| 1984年 | 57115篇 |
| 1983年 | 48133篇 |
| 1982年 | 28291篇 |
| 1981年 | 25074篇 |
| 1979年 | 50564篇 |
| 1978年 | 35263篇 |
| 1977年 | 30597篇 |
| 1976年 | 27779篇 |
| 1975年 | 30124篇 |
| 1974年 | 35366篇 |
| 1973年 | 33748篇 |
| 1972年 | 31863篇 |
| 1971年 | 29628篇 |
| 1970年 | 27242篇 |
| 1969年 | 26231篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
51.
Maggie L. Westfal David C. Chang Cassandra M. Kelleher 《Journal of pediatric surgery》2019,54(1):140-144
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52.
A. Ríos A.I. López-Navas M.A. Ayala G. Garrido M.J. Sebastián J. Carrillo Á. Sánchez J. Flores-Medina J.J. Ruiz-Manzanera A.M. Hernández P. Ramírez P. Parrilla 《Transplantation proceedings》2019,51(2):258-260
The Latin American population has a double way of immigration, one toward the United States by proximity and another toward Spain by sociocultural affinity. This population increase is affecting organ donation and transplantation in receiving countries.
Objective
To analyze the brain death (BD) concept knowledge in the Dominican Republic immigrant population in Florida (United States) and Spain.Method
Population under study: Population born in the Dominican Republic, resident in Florida (United States) and in Spain. Inclusion criteria: Population older than 15 years stratified by age and sex. Assessment instrument: Donation attitude questionnaire PCID-DTO-Ríos. Fieldwork: Random selection based on stratification. Immigration support association collaboration in Florida and Spain was needed to locate potential respondents. Completion was anonymous and self-administered, with verbal consent.Results
A total of 123 respondents, 57 residents in Spain and 66 in Florida, have been included in the study. The 27% (n = 33) of the respondents knowledgeable of the BD concept consider it the death of an individual. Of the remainder, 52% (n = 64) do not know about it, and the remaining 21% (n = 26) believe it does not mean the death of a patient. No differences were observed regarding migration countries (P > .05). There was no association of the BD concept with other psychosocial factors analyzed or with the attitude toward organ donation.Conclusions
Knowledge of the BD concept among the Dominican immigrant population is similar in Spain and Florida, and, unlike most studies, there is no objective association with the attitude toward organ donation. 相似文献53.
54.
Anand Dayama Nikolaos Tsilimparis Stephen Kolakowski Nathaniel M. Matolo Misty D. Humphries 《Journal of vascular surgery》2019,69(1):156-163.e1
Background
Chronic limb-threatening ischemia (CLTI), defined as ischemic rest pain or tissue loss secondary to arterial insufficiency, is caused by multilevel arterial disease with frequent, severe infrageniculate disease. The rise in CLTI is in part the result of increasing worldwide prevalence of diabetes, renal insufficiency, and advanced aging of the population. The aim of this study was to compare a bypass-first with an endovascular-first revascularization strategy in patients with CLTI due to infrageniculate arterial disease.Methods
We reviewed the American College of Surgeons National Surgical Quality Improvement Program targeted lower extremity revascularization database from 2012 to 2015 to identify patients with CLTI and isolated infrageniculate arterial disease who underwent primary infrageniculate bypass or endovascular intervention. We excluded patients with a history of ipsilateral revascularization and proximal interventions. The end points were major adverse limb event (MALE), major adverse cardiovascular event (MACE), amputation at 30 days, reintervention, patency, and mortality. Multivariable logistic regression was used to determine the association of a bypass-first or an endovascular-first intervention with outcomes.Results
There were 1355 CLTI patients undergoing first-time revascularization to the infrageniculate arteries (821 endovascular-first revascularizations and 534 bypass-first revascularizations) identified. There was no significant difference in adjusted rate of 30-day MALE in the bypass-first vs endovascular-first revascularization cohort (9% vs 11.2%; odds ratio [OR], 0.73; 95% confidence interval [CI], 0.50-1.08). However, the incidence of transtibial or proximal amputation was lower in the bypass-first cohort (4.3% vs 7.4%; OR, 0.60; CI, 0.36-0.98). Patients with bypass-first revascularization had higher wound complication rates (9.7% vs 3.7%; OR, 2.75; CI, 1.71-4.42) compared with patients in the endovascular-first cohort. Compared with the endovascular-first cohort, the incidence of 30-day MACE was significantly higher in bypass-first patients (6.9% vs 2.6%; adjusted OR, 3.88; CI, 2.18-6.88), and 30-day mortality rates were 3.23% vs 1.8% (adjusted OR, 2.77; CI, 1.26-6.11). There was no difference in 30-day untreated loss of patency, reintervention of treated arterial segment, readmissions, and reoperations between the two cohorts. In subgroup analysis after exclusion of dialysis patients, there was also no significant difference in MALE or amputation between the bypass-first and endovascular-first cohorts.Conclusions
CLTI patients with isolated infrageniculate arterial disease treated by a bypass-first approach have a significantly lower 30-day amputation. However, this benefit was not observed when dialysis patients were excluded. The bypass-first cohort had a higher incidence of MACE compared with an endovascular-first strategy. These results reaffirm the need for randomized controlled trials, such as the Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL-2) trial and Best Endovascular vs Best Surgical Therapy in Patients with Critical Limb Ischemia (BEST-CLI), to provide level 1 evidence for the role of endovascular-first vs bypass-first revascularization strategies in the treatment of this population of challenging patients. 相似文献55.
N. SUVAJD
I&#x; V. EMERIKI&#x;‐MARTINOVI&#x; &#x;. &#x;ARANOVI&#x; M. PETROVI&#x; M. POPOVI&#x; V. ARTIKO M. &#x;UPI&#x; I. ELEZOVI&#x; 《International journal of laboratory hematology》2006,28(5):317-320
We report the case of a littoral‐cell angioma of the spleen, a recently described benign vascular tumour, whose imaging and pathological characteristics have been discussed only by a few authors. The diagnosis was made after elective splenectomy. The CT images, scintigraphy and histological specimens are presented, and differential diagnoses discussed. 相似文献
56.
57.
58.
G Steinitz M C Martín N Gazit-Yaari M L Quesada J de la Nuez R Casillas U Malik Z B Begin 《Applied radiation and isotopes》2006,64(4):520-524
Multi-day signals, generally with duration of 2-10 days, are a prominent temporal variation type of radon (Rn) in geogas in the unsaturated zone. Rare multi-day Rn signals have been found which are characterized by: (a) a declining limb lasting up to 10 days which conforms to the radioactive decay of Rn, (b) recurs at the same location and (c) is recorded in diverse situations-volcanic and seismogenic. It suggested that a Rn blob is injected at a lower level on a steady upward flow of geogas whereby the rise and final fall of the signal are attributed to the edges of the blob while the central Rn-decay segment records the passing of the decaying blob itself. Rn-decay signals are a small subset of multi-day Rn signals which are considered as highly irregular and unusable for the understanding of geophysical processes. In difference, it is concluded that multi-day Rn signals are probably proxies of subtle geodynamic processes at upper crustal levels and are therefore significant for studying such processes. 相似文献
59.