全文获取类型
收费全文 | 80454篇 |
免费 | 4945篇 |
国内免费 | 1605篇 |
专业分类
耳鼻咽喉 | 564篇 |
儿科学 | 1385篇 |
妇产科学 | 1117篇 |
基础医学 | 10580篇 |
口腔科学 | 1637篇 |
临床医学 | 5479篇 |
内科学 | 10789篇 |
皮肤病学 | 1292篇 |
神经病学 | 5461篇 |
特种医学 | 2599篇 |
外国民族医学 | 1篇 |
外科学 | 8257篇 |
综合类 | 8994篇 |
现状与发展 | 8篇 |
一般理论 | 1篇 |
预防医学 | 6386篇 |
眼科学 | 937篇 |
药学 | 12147篇 |
18篇 | |
中国医学 | 4385篇 |
肿瘤学 | 4967篇 |
出版年
2024年 | 145篇 |
2023年 | 995篇 |
2022年 | 2183篇 |
2021年 | 2867篇 |
2020年 | 2229篇 |
2019年 | 2665篇 |
2018年 | 2545篇 |
2017年 | 2695篇 |
2016年 | 2406篇 |
2015年 | 2424篇 |
2014年 | 3047篇 |
2013年 | 4634篇 |
2012年 | 3688篇 |
2011年 | 3610篇 |
2010年 | 2722篇 |
2009年 | 3215篇 |
2008年 | 3499篇 |
2007年 | 4085篇 |
2006年 | 3892篇 |
2005年 | 3649篇 |
2004年 | 3092篇 |
2003年 | 2926篇 |
2002年 | 2460篇 |
2001年 | 2323篇 |
2000年 | 2130篇 |
1999年 | 1932篇 |
1998年 | 1381篇 |
1997年 | 1421篇 |
1996年 | 1250篇 |
1995年 | 1075篇 |
1994年 | 1075篇 |
1993年 | 903篇 |
1992年 | 821篇 |
1991年 | 803篇 |
1990年 | 717篇 |
1989年 | 565篇 |
1988年 | 562篇 |
1987年 | 470篇 |
1986年 | 410篇 |
1985年 | 552篇 |
1984年 | 482篇 |
1983年 | 365篇 |
1982年 | 362篇 |
1981年 | 295篇 |
1980年 | 305篇 |
1979年 | 200篇 |
1978年 | 134篇 |
1977年 | 141篇 |
1976年 | 116篇 |
1975年 | 93篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
This retrospective study aimed to evaluate radiation-induced pneumonitis (RIP) and a related condition that we define in this report—prolonged minimal RIP (pmRIP)—after stereotactic body radiotherapy (SBRT) for Stage I primary lung cancer in patients with chronic obstructive pulmonary disease (COPD). We assessed 136 Stage I lung cancer patients with COPD who underwent SBRT. Airflow limitation on spirometry was classified into four Global Initiative for Chronic Obstructive Lung Disease (GOLD) grades, with minor modifications: GOLD 1 (mild), GOLD 2 (moderate), GOLD 3 (severe) and GOLD 4 (very severe). On this basis, we defined two subgroups: COPD-free (COPD −) and COPD-positive (COPD +). There was no significant difference in overall survival or cause-specific–survival between these groups. Of the 136 patients, 44 (32%) had pmRIP. Multivariate analysis showed that COPD and the Brinkman index were statistically significant risk factors for the development of pmRIP. COPD and the Brinkman index were predictive factors for pmRIP, although our findings also indicate that SBRT can be tolerated in early lung cancer patients with COPD. 相似文献
3.
《Diagnostic and interventional imaging》2020,101(9):555-564
PurposeThe purpose of this study was to determine whether computed tomography (CT)-based machine learning of radiomics features could help distinguish autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC).Materials and MethodsEighty-nine patients with AIP (65 men, 24 women; mean age, 59.7 ± 13.9 [SD] years; range: 21–83 years) and 93 patients with PDAC (68 men, 25 women; mean age, 60.1 ± 12.3 [SD] years; range: 36–86 years) were retrospectively included. All patients had dedicated dual-phase pancreatic protocol CT between 2004 and 2018. Thin-slice images (0.75/0.5 mm thickness/increment) were compared with thick-slices images (3 or 5 mm thickness/increment). Pancreatic regions involved by PDAC or AIP (areas of enlargement, altered enhancement, effacement of pancreatic duct) as well as uninvolved parenchyma were segmented as three-dimensional volumes. Four hundred and thirty-one radiomics features were extracted and a random forest was used to distinguish AIP from PDAC. CT data of 60 AIP and 60 PDAC patients were used for training and those of 29 AIP and 33 PDAC independent patients were used for testing.ResultsThe pancreas was diffusely involved in 37 (37/89; 41.6%) patients with AIP and not diffusely in 52 (52/89; 58.4%) patients. Using machine learning, 95.2% (59/62; 95% confidence interval [CI]: 89.8–100%), 83.9% (52:67; 95% CI: 74.7–93.0%) and 77.4% (48/62; 95% CI: 67.0–87.8%) of the 62 test patients were correctly classified as either having PDAC or AIP with thin-slice venous phase, thin-slice arterial phase, and thick-slice venous phase CT, respectively. Three of the 29 patients with AIP (3/29; 10.3%) were incorrectly classified as having PDAC but all 33 patients with PDAC (33/33; 100%) were correctly classified with thin-slice venous phase with 89.7% sensitivity (26/29; 95% CI: 78.6–100%) and 100% specificity (33/33; 95% CI: 93–100%) for the diagnosis of AIP, 95.2% accuracy (59/62; 95% CI: 89.8–100%) and area under the curve of 0.975 (95% CI: 0.936–1.0).ConclusionsRadiomic features help differentiate AIP from PDAC with an overall accuracy of 95.2%. 相似文献
4.
5.
ABSTRACTThis work collates data from the analysis of complex mixtures analysed in STRmix during routine no-suspect volume crime work. It interrogates the upload rate for these types of mixtures and which component of the profile has been able to be interpreted for upload. The number of profiles giving multiple uploads and the amount of replicate PCR analysis has been collated. 相似文献
6.
Sarah Hallas Andrea Nelson Susan O'Meara Una Adderley Pauline Meskell Jane Nixon Aonghus O'Loughlin Sebastian Probst Wael Tawfick Thomas Wild Georgina Gethin 《Journal of tissue viability》2021,30(3):317-323
BackgroundA venous leg ulcer is a chronic leg wound caused by poor venous blood circulation in the lower limbs. It is a recurring condition causing pain, malodour, reduced mobility, and depression. Randomised controlled trials evaluating treatments for venous leg ulcers provide important evidence to inform clinical decision-making. However, for findings to be useful, outcomes need to be clinically meaningful, consistently reported across trials, and fully reported. Research has identified the large number of outcomes reported in venous leg ulcer trials, impacting both synthesis of results, and clinical decision-making. To address this, a core outcome set will be developed. A core outcome set is an agreed standardised set of outcomes which should be, as a minimum, measured and reported in all trials which evaluate treatment effectiveness for a given indication. A core outcome set has the potential to reduce research waste, improve the utility of RCTs, reduce reporting bias, facilitate treatment comparisons across different sources of evidence and expedite the production of systematic reviews, meta-analyses and evidence-based clinical guidelines.AimThe aim of this project is to develop a core outcome set for research evaluating the effectiveness of interventions for treating venous leg ulceration.MethodsThrough a scoping review of the literature on venous leg ulceration, we will firstly identify a list of candidate outcome domains (broad categories in relation to what is being measured) from randomised controlled trials and qualitative research, and outcomes (specific methods in relation to what is being measured). In two further stages, we will use the resulting lists of outcome domains and outcomes to design two online surveys. A range of stakeholders will be invited to participate in the surveys and they will be asked to indicate which outcome domains and outcomes are most important and should be considered as core in future research reports. 相似文献
7.
Katherine M. Duszynski Nicole L. Pratt John W. Lynch Jesia G. Berry Michael S. Gold 《Vaccine》2019,37(2):280-288
Objective
To determine whether differences in combination DTaP vaccine types at 2, 4 and 6?months of age were associated with mortality (all-cause or non-specific), within 30?days of vaccination.Design
Observational nationwide cohort study.Setting
Linked population data from the Australian Childhood Immunisation Register and National Death Index.Participants
Australian infants administered a combination trivalent, quadrivalent or hexavalent DTaP vaccine (DTaP types) between January 1999 and December 2010 at 2, 4 and 6?months as part of the primary vaccination series. The study population included 2.9, 2.6, & 2.3?million children in the 2, 4 and 6?month vaccine cohorts, respectively.Main outcome measures
Infants were evaluated for the primary outcome of all-cause mortality within 30?days. A secondary outcome was non-specific mortality (unknown cause of death) within 30?days of vaccination. Non-specific mortality was defined as underlying or other cause of death codes, R95 ‘Sudden infant death syndrome’, R96 ‘Other sudden death, cause unknown’, R98 ‘Unattended death’, R99 ‘Other ill-defined and unspecified cause of mortality’ or where no cause of death was recorded.Results
The rate of 30?day all-cause mortality was low and declined from 127.4 to 59.3 deaths per 100,000 person-years between 2 and 6?month cohorts. When compared with trivalent DTaP vaccines, no elevated risk in all-cause or non-specific mortality was seen with any quadrivalent or hexavalent DTaP vaccines, for any cohort.Conclusion
Use of routine DTaP combination vaccines with differing disease antigens administered during the first six months of life is not associated with infant mortality. 相似文献8.
Micro‐evolution of the hepatitis B virus genome in hepatitis B e‐antigen‐positive carriers: Comparison of genotypes B and C at various immune stages 下载免费PDF全文
9.
《The surgeon》2015,13(5):286-291
BackgroundCure of aneurysms which involve the aorta at the level of the visceral arteries and the thoracoabdominal segment remains a considerable surgical enterprise with a relatively high mortality and morbidity despite improvements of the surgical procedure and anesthetic technique. Fenestrated and branched endovascular stent grafts are currently available offering an attractive less invasive option especially for most frail patients. These grafts are relatively recent, technically more demanding to insert than the current stent graft for infrarenal aneurysm and besides, given the relative low frequency of the disease, they are much less used by practitioners. Thus, unconditional widespread of this sophisticated technique may not necessarily benefit patients.MethodsWe reviewed our experiences and articles regarding this concern, 1) who should perform this new technique and 2) in what kind of setting.ConclusionBased on the combined complexities of 1) patients selection, 2) proper planning and manufacturing of the graft, 3) the need for outstanding imaging and operating facilities, 4) and the required endovascular skill of physicians involved in the procedure, we feel that only highly specialized centers should be allowed to perform this complex procedure. 相似文献
10.
Wan-Jie Gu 《Journal of thoracic disease》2015,7(11):1885-1886
It is well known that a meta-analysis of randomized controlled trials aims to increase the power and precision of the estimated intervention effects. However, when a meta-analysis includes a limited number of patients and a small number of events, overestimation of intervention effect estimates may occur and could cause spurious results. Although many biases can cause the overestimation, random error may be the most common cause. Trial sequential analysis (TSA) can explore the independent effect of random error on intervention effect estimates in meta-analyses and protect meta-analyses against overestimation due to random error. 相似文献