全文获取类型
收费全文 | 2119篇 |
免费 | 129篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 32篇 |
妇产科学 | 69篇 |
基础医学 | 188篇 |
口腔科学 | 29篇 |
临床医学 | 372篇 |
内科学 | 520篇 |
皮肤病学 | 15篇 |
神经病学 | 176篇 |
特种医学 | 34篇 |
外科学 | 324篇 |
综合类 | 30篇 |
一般理论 | 1篇 |
预防医学 | 180篇 |
眼科学 | 45篇 |
药学 | 109篇 |
中国医学 | 1篇 |
肿瘤学 | 109篇 |
出版年
2021年 | 25篇 |
2020年 | 18篇 |
2019年 | 30篇 |
2018年 | 36篇 |
2017年 | 19篇 |
2016年 | 26篇 |
2015年 | 26篇 |
2014年 | 58篇 |
2013年 | 68篇 |
2012年 | 107篇 |
2011年 | 86篇 |
2010年 | 66篇 |
2009年 | 67篇 |
2008年 | 105篇 |
2007年 | 108篇 |
2006年 | 97篇 |
2005年 | 100篇 |
2004年 | 99篇 |
2003年 | 95篇 |
2002年 | 80篇 |
2001年 | 47篇 |
2000年 | 49篇 |
1999年 | 31篇 |
1998年 | 25篇 |
1997年 | 22篇 |
1996年 | 24篇 |
1995年 | 22篇 |
1993年 | 11篇 |
1992年 | 37篇 |
1991年 | 41篇 |
1990年 | 44篇 |
1989年 | 38篇 |
1988年 | 29篇 |
1987年 | 39篇 |
1986年 | 46篇 |
1985年 | 24篇 |
1984年 | 22篇 |
1983年 | 29篇 |
1982年 | 15篇 |
1981年 | 15篇 |
1979年 | 30篇 |
1978年 | 21篇 |
1977年 | 18篇 |
1976年 | 13篇 |
1975年 | 14篇 |
1974年 | 13篇 |
1973年 | 16篇 |
1972年 | 13篇 |
1971年 | 12篇 |
1969年 | 15篇 |
排序方式: 共有2249条查询结果,搜索用时 15 毫秒
91.
Alexander L Lundberg Ramon Lorenzo-Redondo Egon A Ozer Claudia A Hawkins Judd F Hultquist Sarah B Welch PV Vara Prasad James F Oehmke Chad J Achenbach Robert L Murphy Janine I White Robert J Havey Lori Ann Post 《JMIR Public Health and Surveillance》2022,8(1)
BackgroundVariants of the SARS-CoV-2 virus carry differential risks to public health. The Omicron (B.1.1.529) variant, first identified in Botswana on November 11, 2021, has spread globally faster than any previous variant of concern. Understanding the transmissibility of Omicron is vital in the development of public health policy.ObjectiveThe aim of this study is to compare SARS-CoV-2 outbreaks driven by Omicron to those driven by prior variants of concern in terms of both the speed and magnitude of an outbreak.MethodsWe analyzed trends in outbreaks by variant of concern with validated surveillance metrics in several southern African countries. The region offers an ideal setting for a natural experiment given that most outbreaks thus far have been driven primarily by a single variant at a time. With a daily longitudinal data set of new infections, total vaccinations, and cumulative infections in countries in sub-Saharan Africa, we estimated how the emergence of Omicron has altered the trajectory of SARS-CoV-2 outbreaks. We used the Arellano-Bond method to estimate regression coefficients from a dynamic panel model, in which new infections are a function of infections yesterday and last week. We controlled for vaccinations and prior infections in the population. To test whether Omicron has changed the average trajectory of a SARS-CoV-2 outbreak, we included an interaction between an indicator variable for the emergence of Omicron and lagged infections.ResultsThe observed Omicron outbreaks in this study reach the outbreak threshold within 5-10 days after first detection, whereas other variants of concern have taken at least 14 days and up to as many as 35 days. The Omicron outbreaks also reach peak rates of new cases that are roughly 1.5-2 times those of prior variants of concern. Dynamic panel regression estimates confirm Omicron has created a statistically significant shift in viral spread.ConclusionsThe transmissibility of Omicron is markedly higher than prior variants of concern. At the population level, the Omicron outbreaks occurred more quickly and with larger magnitude, despite substantial increases in vaccinations and prior infections, which should have otherwise reduced susceptibility to new infections. Unless public health policies are substantially altered, Omicron outbreaks in other countries are likely to occur with little warning. 相似文献
92.
The Elder Patient with Suspected Acute Coronary Syndromes in the Emergency Department 总被引:1,自引:0,他引:1
Jin H. Han MD MSc Christopher J. Lindsell PhD Richard W. Hornung DrPH Timothy Lewis MD Alan B. Storrow MD James W. Hoekstra MD Judd E. Hollander MD Chadwick D. Miller MD W. Frank Peacock MD Charles V. Pollack MD MA W. Brian Gibler MD 《Academic emergency medicine》2007,14(8):732-739
Objectives To describe the evaluation and outcomes of elder patients with suspected acute coronary syndromes (ACS) presenting to the emergency department (ED). Methods This was a post hoc analysis of the Internet Tracking Registry for Acute Coronary Syndromes (i?trACS) registry, which had 17,713 ED visits for suspected ACS. First visits from the United States with nonmissing patient demographics, 12‐lead electrocardiogram results, and clinical history were included in the analysis. Those who used cocaine or amphetamines or left the ED against medical advice were excluded. Elder was defined as age 75 years or older. ACS was defined by 30‐day revascularization, Diagnosis‐related Group codes, or death within 30 days with positive cardiac biomarkers at index hospitalization. Multivariable logistic regression analyses were performed to determine the association between being elder and 1) 30‐day all‐cause mortality, 2) ACS, 3) diagnostic tests ordered, and 4) disposition. Multivariable logistic regression was also performed to determine which clinical variables were associated with ACS in elder and nonelder patients. Results A total of 10,126 patients with suspected ACS presenting to the ED were analyzed. For patients presenting to the ED, being elder was independently associated with ACS and all‐cause 30‐day mortality, with adjusted odds ratios of 1.8 (95% confidence interval [CI] = 1.5 to 2.2) and 2.6 (95% CI = 1.6 to 4.3), respectively. Elder patients were more likely to be admitted to the hospital (adjusted odds ratio, 2.2; 95% CI = 1.8 to 2.6), but there were no differences in the rates of cardiac catheterization and noninvasive stress cardiac imaging. Different clinical variables were associated with ACS in elder and nonelder patients. Chest pain as chief complaint, typical chest pain, and previous history of coronary artery disease were significantly associated with ACS in nonelder patients but were not associated with ACS in elder patients. Male gender and left arm pain were associated with ACS in both elder and nonelder patients. Conclusions Elder patients who present to the ED with suspected ACS represent a population at high risk for ACS and 30‐day mortality. Elders are more likely to be admitted to the hospital, but despite an increased risk for adverse events, they have similar odds of receiving a diagnostic test, such as stress cardiac imaging or cardiac catheterization, compared with nonelder patients. Different clinical variables are associated with ACS, and clinical prediction rules utilizing presenting symptoms should consider the effect modification of age. 相似文献
93.
Endacott R Wood A Judd F Hulbert C Thomas B Grigg M 《The Australian and New Zealand journal of psychiatry》2006,40(11-12):987-994
OBJECTIVE: To explore the extent and impact of professional boundary crossings in metropolitan, regional and rural mental health practice in Victoria and identify strategies mental health clinicians use to manage dual relationships. METHOD: Nine geographically located focus groups consisting of mental health clinicians: four focus groups in rural settings; three in a regional city and two in a metropolitan mental health service. A total of 52 participants were interviewed. RESULTS: Data revealed that professional boundaries were frequently breached in regional and rural settings and on occasions these breaches had a significantly negative impact. Factors influencing the impact were: longevity of the clinician's relationship with the community, expectations of the community, exposure to community 'gossip' and size of the community. Participants reported greater stress when the boundary crossing affected their partner and/or children. Clinicians used a range of proactive and reactive strategies, such as private telephone number, avoidance of social community activities, when faced with a potential boundary crossing. The feasibility of reactive strategies depended on the service configuration: availability of an alternative case manager, requirement for either patient or clinician to travel. The greater challenges faced by rural and regional clinicians were validated by metropolitan participants with rural experience and rural participants with metropolitan experience. CONCLUSIONS: No single strategy is used or appropriate for managing dual relationships in rural settings. Employers and professional bodies should provide clearer guidance for clinicians both in the management of dual relationships and the distinction between boundary crossings and boundary violation. Clinicians are clearly seeking to represent and protect the patients' interests; consideration should be given by consumer groups to steps that can be taken by patients to reciprocate. 相似文献
94.
95.
96.
97.
Leo Jeng Alexandra V Yamshchikov Suzanne E Judd Henry M Blumberg Gregory S Martin Thomas R Ziegler Vin Tangpricha 《Journal of translational medicine》2009,7(1):28
Background
Vitamin D insufficiency is common in hospitalized patients. Recent evidence suggests that vitamin D may enhance the innate immune response by induction of cathelicidin (LL-37), an endogenous antimicrobial peptide produced by macrophages and neutrophils. Thus, the relationship between vitamin D status and LL-37 production may be of importance for host immunity, but little data is available on this subject, especially in the setting of human sepsis syndrome and other critical illness. 相似文献98.
99.
100.