全文获取类型
收费全文 | 2736篇 |
免费 | 190篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 103篇 |
妇产科学 | 44篇 |
基础医学 | 331篇 |
口腔科学 | 19篇 |
临床医学 | 435篇 |
内科学 | 389篇 |
皮肤病学 | 19篇 |
神经病学 | 388篇 |
特种医学 | 39篇 |
外科学 | 254篇 |
综合类 | 27篇 |
一般理论 | 1篇 |
预防医学 | 527篇 |
眼科学 | 16篇 |
药学 | 177篇 |
中国医学 | 1篇 |
肿瘤学 | 132篇 |
出版年
2023年 | 17篇 |
2022年 | 39篇 |
2021年 | 79篇 |
2020年 | 32篇 |
2019年 | 57篇 |
2018年 | 73篇 |
2017年 | 51篇 |
2016年 | 57篇 |
2015年 | 71篇 |
2014年 | 90篇 |
2013年 | 120篇 |
2012年 | 201篇 |
2011年 | 194篇 |
2010年 | 88篇 |
2009年 | 90篇 |
2008年 | 167篇 |
2007年 | 158篇 |
2006年 | 147篇 |
2005年 | 136篇 |
2004年 | 155篇 |
2003年 | 132篇 |
2002年 | 112篇 |
2001年 | 30篇 |
2000年 | 25篇 |
1999年 | 28篇 |
1998年 | 26篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 12篇 |
1994年 | 29篇 |
1993年 | 15篇 |
1992年 | 31篇 |
1991年 | 26篇 |
1990年 | 36篇 |
1989年 | 32篇 |
1988年 | 24篇 |
1987年 | 17篇 |
1986年 | 18篇 |
1985年 | 14篇 |
1984年 | 14篇 |
1983年 | 24篇 |
1980年 | 10篇 |
1979年 | 17篇 |
1978年 | 12篇 |
1977年 | 10篇 |
1974年 | 11篇 |
1973年 | 11篇 |
1930年 | 12篇 |
1927年 | 10篇 |
1926年 | 11篇 |
排序方式: 共有2930条查询结果,搜索用时 31 毫秒
1.
2.
3.
Incidence and trends in incidence of definite hypertension were analyzed based on 30 years follow-up of 5,209 subjects in the Framingham Heart Study cohort. Based on pooling of 15 two-year periods, hypertension incidence per biennium increased with age in men from 3.3 per cent at ages 30-39 to 6.2 per cent at ages 70-79, and in women from 1.5 per cent at ages 30-39 to 8.6 per cent at ages 70-79. No consistent trend in incidence rates was evident for either sex from the 1950s through the 1970s. The proportion of hypertensive subjects receiving antihypertensive medication has increased since 1954-58 and exceeded 80 per cent for both men and women ages 60-89 years in 1979-81. Incidence data presented in this report may serve as a baseline for assessing the impact of future public health efforts in the primary prevention of hypertension. 相似文献
4.
Andrew E. Springer Kayan Lewis Steven H. Kelder Maria E. Fernandez Cristina S. Barroso Deanna M. Hoelscher 《Journal of immigrant and minority health / Center for Minority Public Health》2010,12(5):769-780
Research on physical activity (PA) by level of acculturation in Hispanic children is limited and findings have been mixed.
We examined PA participation by primary language used with parents in a representative sample of 4th, 8th, and 11th grade
Texas public school students. Mixed-effects regression models were conducted using cross-sectional data from the 2004–2005
School Physical Activity and Nutrition Study (n = 22,049). Self-reported PA was compared among three language-ethnic groups: Spanish-Hispanic (SH) (referent); English-Hispanic
(EH); and English-Other (EO). EH and/or EO girls were generally between 1.25 and 2.58 [OR] times more likely to participate in PA across grade levels,
with the largest differences found for school sports in 8th grade girls. EH and EO 8th grade boys were 1.71 (CI: 1.40, 2.10)
and 2.06 (CI: 1.68, 2.51) times, respectively, more likely to participate in school sports. Findings indicate important disparities
in Spanish-speaking Hispanic children’s PA participation. 相似文献
5.
6.
Donor availability as the primary determinant of the future of heart transplantation 总被引:2,自引:0,他引:2
Heart transplantation has now achieved a therapeutic status similar to that of cadaveric renal transplantation. Depending on patient selection criteria, it is estimated that as many as 15,000 people per year could conceivably benefit from a heart transplant, but the actual number of persons who will benefit is severely constrained by donor supply. Availability of heart donors was estimated based on data obtained on 1,955 organ donors in the United States. The results show that because of age and other contraindications, only 400 to 1,100 viable donor hearts may be available each year. Donor supply is the most critical determinant of the future of heart transplantation since it will dictate the number of transplants performed, the survival of transplant recipients, the total program expenditures associated with heart transplantation, the nature of the legal and ethical issues involved, the number of cardiac transplant programs required to make optimal use of the available donor hearts, and the future role of mechanical circulatory support systems. 相似文献
7.
Aaron Bonner-Jackson John G Csernansky Deanna M Barch 《Neuropsychopharmacology》2007,61(10):1141-1147
BACKGROUND: First-degree relatives of individuals with schizophrenia show cognitive impairments that are similar to but less severe than their ill relatives. We have shown that memory impairments can be improved and prefrontal cortical (PFC) activity increased in individuals with schizophrenia by providing beneficial encoding strategies. The current study used a similar paradigm to determine whether siblings of individuals with schizophrenia (SIBs) also show increases in brain activity when presented with beneficial encoding strategies. METHODS: Twenty-one SIBs and 38 siblings of healthy comparison subjects underwent functional magnetic resonance imaging scans while engaged in deep (abstract/concrete judgments) and shallow (orthographic judgments) encoding. Subjects were then given a recognition memory test. RESULTS: The groups did not differ on encoding or recognition accuracy, and the SIBs benefited from deep encoding to a similar degree as control subjects. The SIBs showed deep encoding-related activity in a number of PFC regions typically activated during semantic processing. However, SIBs showed more activity than control subjects in three subregions of PFC (left BA 44 & BA 47 bilaterally). CONCLUSIONS: Siblings of individuals with schizophrenia benefit from supportive verbal encoding conditions. Like individuals with schizophrenia, SIBs also show increased task-related activity in a larger number of PFC subregions than control subjects during deep verbal encoding. 相似文献
8.
Operative cholangiography 总被引:3,自引:0,他引:3
E H Shively T J Wieman A L Adams R B Romines R N Garrison 《American journal of surgery》1990,159(4):380-4; discussion 385
The value of operative cholangiography in the management of biliary tract disease has been questioned. To better define the role of cholangiography, we reviewed 579 consecutive cholecystectomies done by 1 group of surgeons in a small rural practice over 8 years. Cholangiography demonstrated unsuspected common bile duct disease in 5% of the procedures, while 12% of the patients were spared an unnecessary choledochotomy after a normal cholangiogram was obtained. There was no morbidity, mortality, or prolongation of the hospital stay attributed to the cholangiographic procedure. These findings bolster the argument for routine cholangiography as a safe, effective, and helpful screening examination for patients who are at risk for having common bile duct disease. 相似文献
9.
Miriam Stewart Linda Reutter Edward Makwarimba Irving Rootman Deanna Williamson Kim Raine Doug Wilson Janet Fast Rhonda Love Sharon McFall Deana Shorten Nicole Letourneau Karen Hayward Jeff Masuda William Rutakumwa 《Revue canadienne de recherche en sciences infirmières》2005,37(3):104-131
Poverty influences health status, life expectancy, health behaviours, and use of health services. This study examined factors influencing the use of health-related services by people living in poverty. In the first phase, 199 impoverished users of health-related services in 2 large Canadian cities were interviewed by their peers. In the second phase, group interviews with people living in poverty (n = 52) were conducted. Data were analyzed using thematic content analysis. Diverse health-related services were used to meet basic and health needs, to maintain human contact, and to cope with life's challenges. Use of services depended on proximity, affordability, convenience, information, and providers' attitudes and behaviours. Use was impeded by inequities based on income status. To promote the health of people living in poverty, nurses and other health professionals can enhance the accessibility and quality of services, improve their interactions with people living in poverty, provide information about available programs, offer coordinated community-based services, collaborate with other sectors, and advocate for more equitable services and policies. 相似文献
10.
Gregory C Gray Troy McCarthy Mark G Lebeck David P Schnurr Kevin L Russell Adriana E Kajon Marie L Landry Diane S Leland Gregory A Storch Christine C Ginocchio Christine C Robinson Gail J Demmler Michael A Saubolle Sue C Kehl Rangaraj Selvarangan Melissa B Miller James D Chappell Danielle M Zerr Deanna L Kiska Diane C Halstead Ana W Capuano Sharon F Setterquist Margaret L Chorazy Jeffrey D Dawson Dean D Erdman 《Clinical infectious diseases》2007,45(9):1120-1131
BACKGROUND: Recently, epidemiological and clinical data have revealed important changes with regard to clinical adenovirus infection, including alterations in antigenic presentation, geographical distribution, and virulence of the virus. METHODS: In an effort to better understand the epidemiology of clinical adenovirus infection in the United States, we adopted a new molecular adenovirus typing technique to study clinical adenovirus isolates collected from 22 medical facilities over a 25-month period during 2004-2006. A hexon gene sequence typing method was used to characterize 2237 clinical adenovirus-positive specimens, comparing their sequences with those of the 51 currently recognized prototype human adenovirus strains. In a blinded comparison, this method performed well and was much faster than the classic serologic typing method. RESULTS: Among civilians, the most prevalent adenovirus types were types 3 (prevalence, 34.6%), 2 (24.3%), 1 (17.7%), and 5 (5.3%). Among military trainees, the most prevalent types were types 4 (prevalence, 92.8%), 3 (2.6%), and 21 (2.4%). CONCLUSIONS: For both populations, we observed a statistically significant increasing trend of adenovirus type 21 detection over time. Among adenovirus isolates recovered from specimens from civilians, 50% were associated with hospitalization, 19.6% with a chronic disease condition, 11% with a bone marrow or solid organ transplantation, 7.4% with intensive care unit stay, and 4.2% with a cancer diagnosis. Multivariable risk factor modeling for adenovirus disease severity found that age <7 years (odds ratio [OR], 3.2; 95% confidence interval [CI], 1.4-7.4), chronic disease (OR, 3.6; 95% CI, 2.6-5.1), recent transplantation (OR, 2.7; 95% CI, 1.3-5.2), and adenovirus type 5 (OR, 2.7; 95% CI, 1.5-4.7) or type 21 infection (OR, 7.6; 95% CI, 2.6-22.3) increased the risk of severe disease. 相似文献