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   1412060篇
  免费   113280篇
  国内免费   3337篇
耳鼻咽喉   18386篇
儿科学   46563篇
妇产科学   41121篇
基础医学   200897篇
口腔科学   37699篇
临床医学   126065篇
内科学   284538篇
皮肤病学   33355篇
神经病学   117087篇
特种医学   53854篇
外国民族医学   464篇
外科学   210655篇
综合类   32762篇
现状与发展   3篇
一般理论   490篇
预防医学   110018篇
眼科学   31584篇
药学   98590篇
  1篇
中国医学   3348篇
肿瘤学   81197篇
  2021年   10867篇
  2019年   11685篇
  2018年   16598篇
  2017年   12688篇
  2016年   14290篇
  2015年   16032篇
  2014年   22583篇
  2013年   33431篇
  2012年   45447篇
  2011年   47987篇
  2010年   28196篇
  2009年   27076篇
  2008年   44370篇
  2007年   46874篇
  2006年   47439篇
  2005年   45913篇
  2004年   43809篇
  2003年   41753篇
  2002年   40215篇
  2001年   73029篇
  2000年   74571篇
  1999年   61592篇
  1998年   16999篇
  1997年   15443篇
  1996年   15596篇
  1995年   14796篇
  1994年   13403篇
  1993年   12596篇
  1992年   45856篇
  1991年   43503篇
  1990年   41508篇
  1989年   39562篇
  1988年   36197篇
  1987年   35362篇
  1986年   32866篇
  1985年   31288篇
  1984年   23832篇
  1983年   20029篇
  1982年   12213篇
  1981年   10783篇
  1979年   20704篇
  1978年   14578篇
  1977年   12087篇
  1976年   11366篇
  1975年   11621篇
  1974年   13991篇
  1973年   13539篇
  1972年   12636篇
  1971年   11472篇
  1970年   10917篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
First described in 1955 in New Jersey, epizootic haemorrhagic disease (EHD) causes a severe clinical disease in wild and domestic ruminants worldwide. Epizootic haemorrhagic disease outbreaks occur in deer populations each year from summer to late autumn. The etiological agent is EHD virus (EHDV) which is a double‐stranded segmented icosahedral RNA virus. EHD virus utilizes point mutations and reassortment strategies to maintain viral fitness during infection. In 2018, EHDV serotype 2 was predominantly detected in deer in Illinois. Whole genome sequencing was conducted for two 2018 EHDV2 isolates (IL41747 and IL42218) and the sequence analyses indicated that IL42218 was a reassortant between different serotypes whereas IL41747 was a genetically stable strain. Our data suggest that multiple strains contribute to outbreaks each year.  相似文献   
82.
83.
84.

Background Context

Low back pain (LBP) is a common complaint in clinical practice of multifactorial origin. Although obesity has been thought to contribute to LBP primarily by altering the distribution of mechanical loads on the spine, the additional contribution of obesity-related conditions such as diabetes mellitus (DM) to LBP has not been thoroughly examined.

Purpose

To determine if there is a relationship between DM and LBP that is independent of body mass index (BMI) in a large cohort of adult survey participants.

Study Design

Retrospective analysis of prospectively collected National Health and Nutrition Examination Survey (NHANES) data to characterize associations between LBP, DM, and BMI in adults subdivided into 6 subpopulations: normal weight (BMI 18.5–25), overweight (BMI 25–30), and obese (BMI >30) diabetics and nondiabetics. Diabetes was defined with glycohemoglobin A1c (HbA1c) 6.5%.

Patient Sample

11,756 participants from NHANES cohort.

Outcome Measures

Percentage of LBP reported.

Methods

LBP reported in the 1999-2004 miscellaneous pain NHANES questionnaire was the dependent variable examined. Covariates included HbA1c, BMI, age, and family income ratio to poverty as continuous variables as well as race, gender, and smoking as binary variables. Individuals were further subdivided by weight class and diabetes status. Regression and graphical analyses were performed on the study population as a whole and also on subpopulations.

Results

Increasing HbA1c did not increase the odds of reporting LBP in the full cohort. However, multivariate logistic regression of the 6 subpopulations revealed that the odds of LBP significantly increased with increasing HbA1c levels in normal weight diabetics. No other subpopulations reported significant relationships between LBP and HbA1c. LBP was also significantly associated with BMI for normal weight diabetics and also for obese subjects regardless of their DM status.

Conclusions

LBP is significantly related to DM status, but this relationship is complex and may interact with BMI. These results support the concept that LBP may be improved in normal weight diabetic subjects with improved glycemic control and weight loss, and that all obese LBP subjects may benefit from improved weight loss alone.  相似文献   
85.
Affinity peptide and protein‐ (APP) based radiotracers are an increasingly popular class of radiotracer in positron emission tomography (PET), which was once dominated by the use of small molecule radiotracers. Radiolabelled monoclonal antibodies (mAbs) are important examples of APPs, yet a preference for smaller APPs, which exhibit fast pharmacokinetics and permit rapid PET aided diagnosis, has become apparent. 18F exhibits favourable physical characteristics for APP radiolabelling and has been described as an ideal PET radionuclide. Notwithstanding, 18F radiolabelling of APP is challenging, and this is echoed in the literature where a number of diverse approaches have been adopted. This review seeks to assess and compare the approaches taken to 18F APP radiolabelling with the intention of highlighting trends within this expanding field. Generic themes have emerged in the literature, namely the use of mild radiolabelling conditions, a preference of site‐specific methodologies with an impetus for short, automated procedures which produce high‐yielding [18F]APPs.  相似文献   
86.
87.
88.

Introduction

Physician communication impacts patient outcomes. However, communication skills, especially around difficult conversations, remain suboptimal, and there is no clear way to determine the validity of entrustment decisions. The aims of this study were to 1) describe the development of a simulation-based mastery learning (SBML) curriculum for breaking bad news (BBN) conversation skills and 2) set a defensible minimum passing standard (MPS) to ensure uniform skill acquisition among learners.

Innovation

An SBML BBN curriculum was developed for fourth-year medical students. An assessment tool was created to evaluate the acquisition of skills involved in a BBN conversation. Pilot testing was completed to confirm improvement in skill acquisition and set the MPS.

Outcomes

A BBN assessment tool containing a 15-item checklist and six scaled items was developed. Students' checklist performance improved significantly at post-test compared to baseline (mean 65.33%, SD = 12.09% vs mean 88.67%, SD = 9.45%, P < 0.001). Students were also significantly more likely to have at least a score of 4 (on a five-point scale) for the six scaled questions at post-test. The MPS was set at 80%, requiring a score of 12 items on the checklist and at least 4 of 5 for each scaled item. Using the MPS, 30% of students would require additional training after post-testing.

Comments

We developed a SBML curriculum with a comprehensive assessment of BBN skills and a defensible competency standard. Future efforts will expand the mastery model to larger cohorts and assess the impact of rigorous education on patient care outcomes.  相似文献   
89.
Brian C. Werner 《Arthroscopy》2019,35(4):1072-1073
Achieving tendon-bone healing continues to be challenging after arthroscopic rotator cuff repair, particularly for larger tears, despite significant improvements in repair techniques and implants. Considerable effort has been invested in research to identify methods to improve healing, including patches and injectable biologics. Parathyroid hormone improves tendon-to-bone healing. Teriparatide is osteogenic, stimulating bone growth, and chondrogenic, promoting cartilage formation at the enthesis. However, it could be difficult to justify the expense and potential risk of systemic administration of a recombinant hormone to improve structural healing until improvement in clinical outcomes can be shown.  相似文献   
90.

Background

Patients undergoing cardiac surgery are at significant risk of developing postoperative acute kidney injury (AKI). Neutrophil–lymphocyte ratio (NLR) is a widely available inflammatory biomarker which may be of prognostic value in this setting.

Methods

We conducted a systematic review and meta-analysis of studies reporting associations between perioperative NLR with postoperative AKI. We searched Medline, Embase and the Cochrane Library, without language restriction, from inception to May 2022 for relevant studies. We meta-analysed the reported odds ratios (ORs) with 95% confidence intervals (CIs) for both elevated preoperative and postoperative NLR with risk of postoperative AKI and need for renal replacement therapy (RRT). We conducted a meta-regression to explore inter-study statistical heterogeneity.

Results

Twelve studies involving 10,724 participants undergoing cardiac surgery were included, with eight studies being deemed at high risk of bias using PROBAST modelling. We found statistically significant associations between elevated preoperative NLR and postoperative AKI (OR 1.45, 95% CI 1.18–1.77), as well as postoperative need for RRT (OR 2.37, 95% CI 1.50–3.72). Postoperative NLR measurements were not of prognostic significance.

Conclusions

Elevated preoperative NLR is a reliable inflammatory biomarker for predicting AKI following cardiac surgery.  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