全文获取类型
收费全文 | 1149469篇 |
免费 | 80360篇 |
国内免费 | 2282篇 |
专业分类
耳鼻咽喉 | 15321篇 |
儿科学 | 29925篇 |
妇产科学 | 27362篇 |
基础医学 | 160004篇 |
口腔科学 | 32377篇 |
临床医学 | 103040篇 |
内科学 | 229079篇 |
皮肤病学 | 22281篇 |
神经病学 | 94098篇 |
特种医学 | 46229篇 |
外国民族医学 | 92篇 |
外科学 | 185958篇 |
综合类 | 20409篇 |
现状与发展 | 2篇 |
一般理论 | 402篇 |
预防医学 | 77318篇 |
眼科学 | 26405篇 |
药学 | 86888篇 |
4篇 | |
中国医学 | 2455篇 |
肿瘤学 | 72462篇 |
出版年
2021年 | 10432篇 |
2019年 | 10496篇 |
2018年 | 14464篇 |
2017年 | 11093篇 |
2016年 | 12233篇 |
2015年 | 14101篇 |
2014年 | 19647篇 |
2013年 | 27854篇 |
2012年 | 39868篇 |
2011年 | 41582篇 |
2010年 | 24195篇 |
2009年 | 22888篇 |
2008年 | 39254篇 |
2007年 | 41046篇 |
2006年 | 41504篇 |
2005年 | 40320篇 |
2004年 | 38630篇 |
2003年 | 36450篇 |
2002年 | 35430篇 |
2001年 | 56534篇 |
2000年 | 57882篇 |
1999年 | 48837篇 |
1998年 | 13338篇 |
1997年 | 11550篇 |
1996年 | 11410篇 |
1995年 | 10567篇 |
1994年 | 9703篇 |
1993年 | 8999篇 |
1992年 | 36414篇 |
1991年 | 34787篇 |
1990年 | 33478篇 |
1989年 | 32570篇 |
1988年 | 29635篇 |
1987年 | 28826篇 |
1986年 | 26885篇 |
1985年 | 25789篇 |
1984年 | 18679篇 |
1983年 | 15899篇 |
1982年 | 8784篇 |
1979年 | 16226篇 |
1978年 | 11090篇 |
1977年 | 9477篇 |
1976年 | 8275篇 |
1975年 | 8925篇 |
1974年 | 10760篇 |
1973年 | 10109篇 |
1972年 | 9528篇 |
1971年 | 8999篇 |
1970年 | 8531篇 |
1969年 | 8001篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Brian Darrith Nicholas B. Frisch Matthew W. Tetreault Michael P. Fice Chris N. Culvern Craig J. Della Valle 《The Journal of arthroplasty》2019,34(2):221-227
Background
Although some prior work supports the safety of same-day arthroplasty performed in a hospital, concerns remain when these procedures are performed in a free-standing ambulatory surgery center. The purpose of this study is to compare 90-day complication rates between matched cohorts that underwent inpatient vs outpatient arthroplasty at an ambulatory surgery center.Methods
A single-surgeon cohort of 243 consecutive patients who underwent outpatient arthroplasty was matched with 243 inpatients who had the same procedure. One-to-one nearest-neighbor matching with respect to gender, age, American Society of Anesthesiologists Score, and body mass index was utilized. The 486 primary arthroplasties included 178 unicondylar knees (36.6%), 146 total hips (30.0%), 92 total knees (18.9%), and 70 hip resurfacings (14.5%). Ninety-day outcomes including reoperation, readmission, unplanned clinic or emergency department visits, and major and minor complications were compared using a 2-sample proportions test.Results
The 2 cohorts were similar in distribution of demographic variables, demonstrating successful matching. The inpatient and outpatient cohorts both had readmission rates of 2.1% (P = 1.0). With the number of subjects studied, there were no statistically significant differences in rates of major complications (2.1% vs 2.5%, P = 1.0), minor complications (7.0% vs 7.8%, P = .86), reoperations (0.4% vs 2.1%, P = .22), emergency department visits (1.6% vs 2.5%, P = .52), or unplanned clinic visits (3.3% vs 5.8%, P = .19).Conclusion
This study suggests that arthroplasty procedures can be performed safely in an ambulatory surgery center among appropriately selected patients without an increased risk of complications. 相似文献22.
Chancellor F. Gray Hernan A. Prieto Justin T. Deen Hari K. Parvataneni 《The Journal of arthroplasty》2019,34(2):206-210
Background
Revision total joint arthroplasty (TJA) is associated with increased readmissions, complications, and expense compared to primary TJA. Bundled payment methods have been used to improve value of care in primary TJA, but little is known of their impact in revision TJA patients. The purpose of this study is to evaluate the impact of a care redesign for a bundled payment model for primary TJA on quality metrics for revision patients, despite absence of a targeted intervention for revisions.Methods
We compared quality metrics for all revision TJA patients including readmission rate, use of post–acute care facility after discharge, length of stay, and cost, between the year leading up to the redesign and the 2 years following its implementation. Changes in the primary TJA group over the same time period were also assessed for comparison.Results
Despite a volume increase of 37% over the study period, readmissions declined from 8.9% to 5.8%. Use of post–acute care facilities decreased from 42% to 24%. Length of stay went from 4.84 to 3.92 days. Cost of the hospital episode declined by 5%.Conclusion
Our health system experienced a halo effect from our bundled payment-influenced care redesign, with revision TJA patients experiencing notable improvements in several quality metrics, though not as pronounced as in the primary TJA population. These changes benefitted the patients, the health system, and the payers. We attribute these positive changes to an altered institutional mindset, resulting from an invested and aligned care team, with active physician oversight over the care episode. 相似文献23.
Andreu Porta-Sánchez Andrew C.T. Ha Xuesong Wang Fahad Almehmadi Peter C. Austin Hadas D. Fischer Atif Al-Qubbany Diego Chemello Vijay Chauhan Eugene Downar Douglas S. Lee Kumaraswamy Nanthakumar 《The Canadian journal of cardiology》2019,35(2):169-177
Background
Catheter ablation of ventricular tachycardia (VT) can reduce the burden of ventricular arrhythmia (VA) but its effect on health care utilization and costs after such therapy is poorly known. We sought to compare the rates of cardiovascular (CV)-related hospitalizations, survival, and health care costs in patients with recurrent VT treated either with VT ablation or with medical therapy.Methods
One-hundred implantable cardioverter-defibrillator patients with structural heart disease who underwent VT ablation were included. Propensity score-matched patients with recurrent VT treated with medical therapy were identified from a prospective registry of approximately 7000 de novo implantable cardioverter-defibrillator patients. Outcomes and costs were ascertained using health administrative databases.Results
Among patients who underwent VT ablation, the cumulative rates of VA-related hospitalizations were lower in the 2 years after their ablation procedure compared with the year before (rate ratio, 0.3; 95% confidence interval [CI], 0.22-0.43). Rates of CV-related hospitalization and hospitalization because of VA post index date were similar between the VT ablation and medical therapy groups (hazard ratio [HR], 0.94; 95% CI, 0.57-1.54 and HR, 1.04; 95% CI, 0.57-1.91, respectively). Health care costs in the VT ablation patients were not increased post-ablation compared with the medical management group. The risk of all-cause mortality was lower among patients in the VT ablation group relative to the medical therapy group (HR, 0.64; 95% CI, 0.4-0.99).Conclusions
Patients who underwent VT ablation experienced a significant reduction in their rate of VA-related hospitalizations. Patients treated with VT ablation had similar rates of CV-related hospitalization compared with those treated with medical therapy without increased health care-related costs. 相似文献24.
Warren Fiskus Christopher P. Mill Behnam Nabet Dimuthu Perera Christine Birdwell Taghi Manshouri Bernardo Lara Tapan M. Kadia Courtney DiNardo Koichi Takahashi Naval Daver Prithviraj Bose Lucia Masarova Naveen Pemmaraju Steven Kornblau Gautam Borthakur Guillermo Montalban-Bravo Guillermo Garcia Manero Sunil Sharma Matthew Stubbs Xiaoping Su Michael R. Green Cristian Coarfa Srdan Verstovsek Joseph D. Khoury Christopher R. Vakoc Kapil N. Bhalla 《Blood cancer journal》2021,11(5)
There is an unmet need to overcome nongenetic therapy-resistance to improve outcomes in AML, especially post-myeloproliferative neoplasm (MPN) secondary (s) AML. Studies presented describe effects of genetic knockout, degradation or small molecule targeted-inhibition of GFI1/LSD1 on active enhancers, altering gene-expressions and inducing differentiation and lethality in AML and (MPN) sAML cells. A protein domain-focused CRISPR screen in LSD1 (KDM1A) inhibitor (i) treated AML cells, identified BRD4, MOZ, HDAC3 and DOT1L among the codependencies. Our findings demonstrate that co-targeting LSD1 and one of these co-dependencies exerted synergistic in vitro lethality in AML and post-MPN sAML cells. Co-treatment with LSD1i and the JAKi ruxolitinib was also synergistically lethal against post-MPN sAML cells. LSD1i pre-treatment induced GFI1, PU.1 and CEBPα but depleted c-Myc, overcoming nongenetic resistance to ruxolitinib, or to BETi in post-MPN sAML cells. Co-treatment with LSD1i and BETi or ruxolitinib exerted superior in vivo efficacy against post-MPN sAML cells. These findings highlight LSD1i-based combinations that merit testing for clinical efficacy, especially to overcome nongenetic therapy-resistance in AML and post-MPN sAML.Subject terms: Acute myeloid leukaemia, Targeted therapies 相似文献
25.
Lindy M. Kregting Sylvia Kaljouw Lucie de Jonge Erik E. L. Jansen Elisabeth F. P. Peterse Eveline A. M. Heijnsdijk Nicolien T. van Ravesteyn Iris Lansdorp-Vogelaar Inge M. C. M. de Kok 《British journal of cancer》2021,124(9):1516
Background Many breast, cervical, and colorectal cancer screening programmes were disrupted due to the COVID-19 pandemic. This study aimed to estimate the effects of five restart strategies after the disruption on required screening capacity and cancer burden.Methods Microsimulation models simulated five restart strategies for breast, cervical, and colorectal cancer screening. The models estimated required screening capacity, cancer incidence, and cancer-specific mortality after a disruption of 6 months. The restart strategies varied in whether screens were caught up or not and, if so, immediately or delayed, and whether the upper age limit was increased.Results The disruption in screening programmes without catch-up of missed screens led to an increase of 2.0, 0.3, and 2.5 cancer deaths per 100 000 individuals in 10 years in breast, cervical, and colorectal cancer, respectively. Immediately catching-up missed screens minimised the impact of the disruption but required a surge in screening capacity. Delaying screening, but still offering all screening rounds gave the best balance between required capacity, incidence, and mortality.Conclusions Strategies with the smallest loss in health effects were also the most burdensome for the screening organisations. Which strategy is preferred depends on the organisation and available capacity in a country.Subject terms: Health policy, Population screening, Cancer screening, Cancer screening 相似文献
26.
27.
A.L. Kühn S.R. Satti T. Eden K. de Macedo Rodrigues J. Singh F. Massari M.J. Gounis A.S Puri 《AJNR. American journal of neuroradiology》2021,42(3):487
BACKGROUND AND PURPOSE:Transradial access for neurointerventional procedures has been proved a safer and more comfortable alternative to femoral artery access. We present our experience with transradial (distal radial/anatomic snuffbox and radial artery) access for treatment of intracranial aneurysms using all 3 FDA-approved flow diverters.MATERIALS AND METHODS:This was a high-volume, dual-center, retrospective analysis of each institution’s data base between June 2018 and June 2020 and a collection of all patients treated with flow diversion via transradial access. Patient demographic information and procedural and radiographic data were obtained.RESULTS:Seventy-four patients were identified (64 female patients) with a mean age of 57.5 years with a total of 86 aneurysms. Most aneurysms were located in the anterior circulation (93%) and within the intracranial ICA (67.4%). The mean aneurysm size was 5.5 mm. Flow diverters placed included the Pipeline Embolization Device (Flex) (PED, n = 65), the Surpass Streamline Flow Diverter (n = 8), and the Flow-Redirection Endoluminal Device (FRED, n = 1). Transradial access was successful in all cases, but femoral crossover was required in 3 cases (4.1%) due to tortuous anatomy and inadequate support of the catheters in 2 cases and an inability to navigate to the target vessel in a patient with an aberrant right subclavian artery. All 71 other interventions were successfully performed via the transradial approach (95.9%). No access site complications were encountered. Asymptomatic radial artery occlusion was encountered in 1 case (3.7%).CONCLUSIONS:Flow diverters can be successfully placed via the transradial approach with high technical success, low access site complications, and a low femoral crossover rate.The transradial access (TRA), including distal radial artery (dRA) access in the anatomic snuffbox and radial artery (RA) access at the palmar surface of the wrist, is being increasingly used as primary vascular access for neurointerventional procedures. In prior years, large randomized trials in the field of interventional cardiology and more recent articles in neurointerventional surgery have shown higher patient preference for the TRA, cost reduction, as well as lower morbidity and mortality compared with the traditional transfemoral access (TFA).1-11 Reduction in access site complications has been a particular advantage of wrist over femoral access and is an important consideration for vascular access choice in the treatment of intracranial aneurysms using flow diversion. Patients undergoing flow diversion are required to take dual-antiplatelet agents and receive heparin during the procedure, all of which increase the risk of bleeding from the access site.12 Also, flow diverters (FDs) may require large-bore catheter assemblies for delivery and deployment, which may increase the risk of radial artery occlusion, access site bleeding, or vascular injury.13,14To date, only a limited number of case reports and case series have described the safety and feasibility of TRA for the treatment of intracranial aneurysms using flow diverters.15-22Recently, a large, retrospective multicenter study reported the safety of TRA for flow diversion, showing a lower access site (P = .039) and overall complication rate (P = .035).12 This study, however, did not cover catheter systems, patient functional outcome, and aneurysm occlusion. Here, we report our experience with TRA (dRA [anatomic snuffbox] and RA) for the treatment of intracranial aneurysms using all 3 FDA-approved flow diverters, including technical feasibility, procedural safety, patient outcome, and aneurysm occlusion on follow-up. Additionally, we reviewed the current literature on use of flow diverters via TRA. 相似文献
28.
M.D. Li M. Lang F. Deng K. Chang K. Buch S. Rincon W.A. Mehan T.M. Leslie-Mazwi J. Kalpathy-Cramer 《AJNR. American journal of neuroradiology》2021,42(3):429
BACKGROUND AND PURPOSE:The coronavirus disease 2019 (COVID-19) pandemic has led to decreases in neuroimaging volume. Our aim was to quantify the change in acute or subacute ischemic strokes detected on CT or MR imaging during the pandemic using natural language processing of radiology reports.MATERIALS AND METHODS:We retrospectively analyzed 32,555 radiology reports from brain CTs and MRIs from a comprehensive stroke center, performed from March 1 to April 30 each year from 2017 to 2020, involving 20,414 unique patients. To detect acute or subacute ischemic stroke in free-text reports, we trained a random forest natural language processing classifier using 1987 randomly sampled radiology reports with manual annotation. Natural language processing classifier generalizability was evaluated using 1974 imaging reports from an external dataset.RESULTS:The natural language processing classifier achieved a 5-fold cross-validation classification accuracy of 0.97 and an F1 score of 0.74, with a slight underestimation (−5%) of actual numbers of acute or subacute ischemic strokes in cross-validation. Importantly, cross-validation performance stratified by year was similar. Applying the classifier to the complete study cohort, we found an estimated 24% decrease in patients with acute or subacute ischemic strokes reported on CT or MR imaging from March to April 2020 compared with the average from those months in 2017–2019. Among patients with stroke-related order indications, the estimated proportion who underwent neuroimaging with acute or subacute ischemic stroke detection significantly increased from 16% during 2017–2019 to 21% in 2020 (P = .01). The natural language processing classifier performed worse on external data.CONCLUSIONS:Acute or subacute ischemic stroke cases detected by neuroimaging decreased during the COVID-19 pandemic, though a higher proportion of studies ordered for stroke were positive for acute or subacute ischemic strokes. Natural language processing approaches can help automatically track acute or subacute ischemic stroke numbers for epidemiologic studies, though local classifier training is important due to radiologist reporting style differences.There is much concern regarding the impact of the coronavirus disease 2019 (COVID-19) pandemic on the quality of stroke care, including issues with hospital capacity, clinical resource re-allocation, and the safety of patients and clinicians.1,2 Previous reports have shown that there have been substantial decreases in stroke neuroimaging volume during the pandemic.3,4 In addition, acute ischemic infarcts have been found on neuroimaging studies in many hospitalized patients with COVID-19, though the causal relationship is unclear.5,6 Studies like these and other epidemiologic analyses usually rely on the creation of manually curated databases, in which identification of cases can be time-consuming and difficult to update in real-time. One way to facilitate such research is to use natural language processing (NLP), which has shown utility for automated analysis of radiology report data.7 NLP algorithms have been developed previously for the classification of neuroradiology reports for the presence of ischemic stroke findings and acute ischemic stroke subtypes.8,9 Thus, NLP has the potential to facilitate COVID-19 research.In this study, we developed an NLP machine learning model that classifies radiology reports for the presence or absence of acute or subacute ischemic stroke (ASIS), as opposed to chronic stroke. We used this model to quantify the change in ASIS detected on all CT or MR imaging studies performed at a large comprehensive stroke center during the COVID-19 pandemic in the United States. We also evaluated NLP model generalizability and different training strategies using a sample of radiology reports from a second stroke center. 相似文献
29.
Swetha Srinivasan Nae Yeon Won W. David Dotson Sarah T. Wright Megan C. Roberts 《European journal of human genetics : EJHG》2020,28(12):1631
Cascade testing is the process of offering genetic counseling and testing to at-risk relatives of an individual who has been diagnosed with a genetic condition. It is critical for increasing the identification rates of individuals with these conditions and the uptake of appropriate preventive health services. The process of cascade testing is highly varied in clinical practice, and a comprehensive understanding of factors that hinder or enhance its implementation is necessary to improve this process. We conducted a systematic review to identify barriers and facilitators for cascade testing and searched PubMed, CINAHL via EBSCO, Web of Science, EMBASE, and the Cochrane Library for articles published from the databases’ inception to November 2018. Thirty articles met inclusion criteria. Barriers and facilitators identified from these studies at the individual-level were organized into the following categories: (1) demographics, (2) knowledge, (3) attitudes, beliefs, and emotional responses of the individual, and (4) perceptions of relatives, relatives’ responses, and attitudes toward relatives. At the interpersonal-level, barriers and facilitators were categorized as (1) family communication-, support- and dynamics-, and (2) provider-factors. Finally, barriers at the environmental-level relating to accessibility of genetic services were also identified. Our findings suggest that several individual, interpersonal and environmental factors may play a role in cascade testing. Future studies to further investigate these barriers and facilitators are needed to inform future interventions for improving the implementation of cascade testing for genetic conditions in clinical practice.Subject terms: Preventive medicine, Genetic services 相似文献
30.
Multiple linear regression is commonly used to test for association between genetic variants and continuous traits and estimate genetic effect sizes. Confounding variables are controlled for by including them as additional covariates. An alternative technique that is increasingly used is to regress out covariates from the raw trait and then perform regression analysis with only the genetic variants included as predictors. In the case of single-variant analysis, this adjusted trait regression (ATR) technique is known to be less powerful than the traditional technique when the genetic variant is correlated with the covariates We extend previous results for single-variant tests by deriving exact relationships between the single-variant score, Wald, likelihood-ratio, and F test statistics and their ATR analogs. We also derive the asymptotic power of ATR analogs of the multiple-variant score and burden tests. We show that the maximum power loss of the ATR analog of the multiple-variant score test is completely characterized by the canonical correlations between the set of genetic variants and the set of covariates. Further, we show that for both single- and multiple-variant tests, the power loss for ATR analogs increases with increasing stringency of Type 1 error control () and increasing correlation (or canonical correlations) between the genetic variant (or multiple variants) and covariates. We recommend using ATR only when maximum canonical correlation between variants and covariates is low, as is typically true. 相似文献