首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7362篇
  免费   521篇
  国内免费   70篇
耳鼻咽喉   64篇
儿科学   192篇
妇产科学   107篇
基础医学   1096篇
口腔科学   142篇
临床医学   555篇
内科学   1605篇
皮肤病学   397篇
神经病学   522篇
特种医学   332篇
外科学   1190篇
综合类   161篇
一般理论   4篇
预防医学   356篇
眼科学   259篇
药学   338篇
中国医学   28篇
肿瘤学   605篇
  2023年   52篇
  2022年   36篇
  2021年   179篇
  2020年   138篇
  2019年   178篇
  2018年   200篇
  2017年   173篇
  2016年   225篇
  2015年   240篇
  2014年   337篇
  2013年   316篇
  2012年   558篇
  2011年   518篇
  2010年   293篇
  2009年   273篇
  2008年   392篇
  2007年   378篇
  2006年   340篇
  2005年   402篇
  2004年   334篇
  2003年   271篇
  2002年   310篇
  2001年   244篇
  2000年   228篇
  1999年   186篇
  1998年   86篇
  1997年   63篇
  1996年   59篇
  1995年   60篇
  1994年   52篇
  1993年   28篇
  1992年   81篇
  1991年   79篇
  1990年   74篇
  1989年   87篇
  1988年   95篇
  1987年   66篇
  1986年   60篇
  1985年   48篇
  1984年   35篇
  1983年   39篇
  1982年   9篇
  1981年   12篇
  1980年   7篇
  1979年   24篇
  1978年   13篇
  1977年   19篇
  1976年   8篇
  1975年   7篇
  1974年   8篇
排序方式: 共有7953条查询结果,搜索用时 15 毫秒
1.
2.
3.
BackgroundCoronavirus disease 2019 (COVID-19) has spread around the globe, and it is important to determine the risk factors of death in the general population. Our study aimed to determine the risk factors of death and severe illness requiring supplemental oxygen therapy based on the demographic and clinical characteristics of COVID-19 patients in Korea.MethodsIn this study, we used data provided by the Korea Disease Control and Prevention Agency (KDCA) and analyzed a total of 5,068 patients with COVID-19, excluding 19 pregnant women and 544 individuals with missing data. We performed logistic regression analysis to determine the impact of early symptoms on survival and severe disease. Logistic regression models included sex, age, number of comorbidities, symptoms on admission, blood pressure, heart rate, and body temperature as explanatory variables, and death and oxygen therapy as outcome variables.ResultsLogistic regression analyses revealed that the male sex, older age (≥ 60 years), higher number of comorbidities, presence of symptoms on admission, heart rate ≥ 120 bpm, and body temperature ≥ 37.5°C presented with higher risk of in-hospital death and oxygen therapy requirement. Conversely, rhinorrhea and headache were associated with a low risk of death and oxygen therapy requirement. The findings showed that cough, sputum, and fever were the most common symptoms on admission, while 25.3% of patients with COVID-19 were asymptomatic.ConclusionCOVID-19 patients with high-risk early symptoms on admission, such as dyspnea and altered mental status, and those without low-risk symptoms of rhinorrhea and headache should be included in priority treatment groups.  相似文献   
4.
BackgroundOsteocalcin is known to regulate energy metabolism. Recently, metabolic syndrome (MetS) has been found to be associated with reduced levels of osteocalcin in men, as well as in postmenopausal women. The aim of this study was to investigate the association between serum osteocalcin and MetS in premenopausal women, compared with that in postmenopausal women.MethodsThis cross-sectional study was based on 5,896 participants who completed a health screening examination. They were classified according to their menopausal status. Each group was subdivided into non-MetS and MetS groups according to the modified National Cholesterol Education Program-Adult Treatment Panel III criteria. Serum osteocalcin levels were measured using the electrochemiluminescence immunoassay.ResultsSerum osteocalcin level was significantly lower in women with MetS than in those without MetS, after adjusting for confounders (14.12 ± 0.04 vs. 13.17 ± 0.13 [P = 0.004] in premenopausal women, and 20.34 ± 0.09 vs. 19.62 ± 0.21 [P < 0.001] in postmenopausal women), regardless of their menopausal status. Serum osteocalcin levels decreased correspondingly with an increasing number of MetS elements (P for trend < 0.001). Multiple regression analysis demonstrated that waist circumference (β = −0.085 [P < 0.001] and β = −0.137 [P < 0.001]) and hemoglobin A1c (β = −0.09 [P < 0.001] and β = −0.145 [P < 0.001]) were independent predictors of osteocalcin in premenopausal and postmenopausal women. Triglyceride levels were also independently associated with osteocalcin levels in premenopausal women (β = −0.004 [P < 0.013]). The odds ratio (OR) for MetS was significantly higher in the lowest quartile than in the highest quartile of serum osteocalcin levels after adjusting for age, alkaline phosphatase, uric acid, high sensitivity C-reactive protein, and body mass index in all women (OR, 2.00; 95% confidence interval [CI], 1.49–2.68) as well as in premenopausal (OR, 2.23; 95% CI, 1.39–3.58) and postmenopausal (OR, 2.01; 95% CI, 1.26–3.23) subgroups.ConclusionLower serum osteocalcin concentrations were significantly associated with MetS in both premenopausal and postmenopausal women and were therefore independent of menopausal status.  相似文献   
5.
ABSTRACT

Introduction

Fifteen percent of proliferating infantile hemangioma (IH) require intervention because of the threat to function or life, ulceration, or tissue distortion. Propranolol is the mainstay treatment for problematic proliferating IH. Other β-blockers and angiotensin-converting enzyme (ACE) inhibitors have been explored as alternative treatments.  相似文献   
6.
7.
8.
Osteoporosis is a common, but silent disease until it is complicated by fractures that are associated with morbidity and mortality. Over the past few years, although deep learning-based disease diagnosis on chest radiographs has yielded promising results, osteoporosis screening remains unexplored. Paired data with 13,026 chest radiographs and dual-energy X-ray absorptiometry (DXA) results from the Health Screening and Promotion Center of Asan Medical Center, between 2012 and 2019, were used as the primary dataset in this study. For the external test, we additionally used the Asan osteoporosis cohort dataset (1089 chest radiographs, 2010 and 2017). Using a well-performed deep learning model, we trained the OsPor-screen model with labels defined by DXA based diagnosis of osteoporosis (lumbar spine, femoral neck, or total hip T-score ≤ −2.5) in a supervised learning manner. The OsPor-screen model was assessed in the internal and external test sets. We performed substudies for evaluating the effect of various anatomical subregions and image sizes of input images. OsPor-screen model performances including sensitivity, specificity, and area under the curve (AUC) were measured in the internal and external test sets. In addition, visual explanations of the model to predict each class were expressed in gradient-weighted class activation maps (Grad-CAMs). The OsPor-screen model showed promising performances. Osteoporosis screening with the OsPor-screen model achieved an AUC of 0.91 (95% confidence interval [CI], 0.90–0.92) and an AUC of 0.88 (95% CI, 0.85–0.90) in the internal and external test set, respectively. Even though the medical relevance of these average Grad-CAMs is unclear, these results suggest that a deep learning-based model using chest radiographs could have the potential to be used for opportunistic automated screening of patients with osteoporosis in clinical settings. © 2021 American Society for Bone and Mineral Research (ASBMR).  相似文献   
9.
ABSTRACT

Objective: There are substantial racial and regional disparities in obesity prevalence in the United States. This study partitioned the mean Body Mass Index (BMI) and obesity prevalence rate gaps between non-Hispanic blacks and non-Hispanic whites into the portion attributable to observable obesity risk factors and the remaining portion attributable to unobservable factors at the national and the state levels in the United States (U.S.) in 2010.

Design: This study used a simulated micro-population dataset combining common information from the Behavioral Risk Factor Surveillance System and the U.S. Census data to obtain a reliable, large sample representing the adult populations at the national and state levels. It then applied a reweighting decomposition method to decompose the black-white mean BMI and obesity prevalence disparities at the national and state levels into the portion attributable to the differences in distribution of observable obesity risk factors and the remaining portion unexplainable with risk factors.

Results: We found that the observable differences in distribution of known obesity risk factors explain 18.5% of the mean BMI difference and 20.6% of obesity prevalence disparities between non-Hispanic blacks and non-Hispanic whites. There were substantial variations in how much the differences in distribution of known obesity risk factors can explain black-white gaps in mean BMI (?67.7% to 833.6%) and obesity prevalence (?278.5% to 340.3%) at the state level.

Conclusion: The results from this study demonstrate that known obesity risk factors explain a small proportion of the racial, ethnic and between-state disparities in obesity prevalence in the United States. Future etiologic studies are required to further understand the causal factors underlying obesity and racial, ethnic and geographic disparities.  相似文献   
10.
INTRODUCTIONRecent studies reported that laparoscopic pancreatoduodenectomy (LPD) is associated with superior perioperative outcomes compared to the open approach. However, concerns have been raised about the safety of LPD, especially during the learning phase. Robotic pancreatoduodenectomy (RPD) has been reported to be associated with a shorter learning curve compared to LPD. We herein present our initial experience with RPD.METHODSA retrospective review of a single-institution prospective robotic hepatopancreaticobiliary (HPB) surgery database of 70 patients identified seven consecutive RPDs performed by a single surgeon in 2016–2017. These were matched at a 1:2 ratio with 14 open pancreatoduodenectomies (OPDs) selected from 77 consecutive pancreatoduodenectomies performed by the same surgeon between 2011 and 2017.RESULTSSeven patients underwent RPD, of which five were hybrid procedures with open reconstruction. There were no open conversions. Median operative time was 710.0 (range 560.0–930.0) minutes. Two major morbidities (> Grade 2) occurred: one gastrojejunostomy bleed requiring endoscopic haemostasis and one delayed gastric emptying requiring feeding tube placement. There were no pancreatic fistulas, reoperations or 90-day/in-hospital mortalities in the RPD group. Comparison between RPD and OPD demonstrated that RPD was associated with a significantly longer operative time. Compared to open surgery, there was no significant difference in estimated blood loss, blood transfusion, postoperative stay, pancreatic fistula rates, morbidity and mortality rates, R0 resection rates, and lymph node harvest rates.CONCLUSIONOur initial experience demonstrates that RPD is feasible and safe in selected patients. It can be safely adopted without any compromise in patient outcomes compared to the open approach.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号