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   5457篇
  免费   760篇
  国内免费   22篇
耳鼻咽喉   116篇
儿科学   175篇
妇产科学   183篇
基础医学   643篇
口腔科学   103篇
临床医学   1148篇
内科学   957篇
皮肤病学   60篇
神经病学   450篇
特种医学   200篇
外国民族医学   1篇
外科学   802篇
综合类   142篇
一般理论   2篇
预防医学   476篇
眼科学   53篇
药学   485篇
中国医学   1篇
肿瘤学   242篇
  2021年   62篇
  2020年   44篇
  2019年   73篇
  2018年   158篇
  2017年   165篇
  2016年   204篇
  2015年   187篇
  2014年   220篇
  2013年   280篇
  2012年   300篇
  2011年   294篇
  2010年   200篇
  2009年   236篇
  2008年   291篇
  2007年   305篇
  2006年   252篇
  2005年   238篇
  2004年   209篇
  2003年   166篇
  2002年   179篇
  2001年   152篇
  2000年   171篇
  1999年   124篇
  1998年   57篇
  1997年   47篇
  1996年   59篇
  1995年   45篇
  1993年   36篇
  1992年   97篇
  1991年   85篇
  1990年   70篇
  1989年   87篇
  1988年   73篇
  1987年   105篇
  1986年   80篇
  1985年   73篇
  1984年   54篇
  1983年   48篇
  1982年   34篇
  1980年   41篇
  1979年   51篇
  1978年   44篇
  1977年   38篇
  1976年   29篇
  1975年   41篇
  1974年   39篇
  1973年   36篇
  1972年   32篇
  1971年   30篇
  1970年   36篇
排序方式: 共有6239条查询结果,搜索用时 0 毫秒
101.
We undertook a trial of artesunate + amodiaquine (AS + AQ) and artesunate + sulphadoxine-pyrimethamine (AS + SP) in 180 children of age 6-59 months with uncomplicated malaria in Democratic Republic of Congo. Children were randomly allocated to receive 3 days observed treatment of AS + AQ (n = 90) or 3 days of AS + SP (n = 90). Primary efficacy outcomes were 28-day parasite recurrence rates, and recrudescence rates were adjusted by genotyping to distinguish new infection and recrudescence. In addition, we determined the prevalence of molecular markers of resistance to sulphadoxine and pyrimethamine. Day 28 parasite recurrence rates were 16.9% (14/83; 95% CI: 9.5-26.7) in the AS + AQ group and 34.6% (28/81; 95% CI: 24.3-46.0) in the AS + SP group (P = 0.009). After PCR correction, recrudescence rates were 6.7% (5/74; 95% CI: 2.2-15.1) for AS + AQ and 19.7% (13/66; 95% CI: 10.9-31.3) for AS + SP (P = 0.02). There was no significant difference between the two arms in time to parasite clearance, fever clearance and gametocyte clearance. Parasite genotyping showed high frequencies of dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) molecular SP-resistance markers, with 57% of the samples showing more than three mutations linked to SP resistance, and 27% with triple-dhfr/double-dhps haplotype, confirming that SP treatment failure rates are likely to be high. AS + AQ had significantly higher efficacy than AS + SP. These results contributed to the subsequent change to AS + AQ as first-line regimen in the country. Efforts to properly implement the new protocol and maintain adherence at acceptable levels should include health staff and patient sensitization. The 6.8% recrudescence rate indicates that AS + AQ should be monitored closely until a more effective artemisinin combination therapy regimen is needed and can be introduced.  相似文献   
102.
Antibody to donor HLA antigens is a significant barrier to both access to and outcome of allogeneic transplants. Many attempts have been made to desensitize patients with HLA-specific antibody, but the most effective and durable have been treatment with high-dose pooled human intravenous immunoglobulin (IVIg) and a combination of plasmapheresis and low-dose IVIg. Despite the success of these treatments, low levels of donor-specific antibody (DSA) persist in some patients. We examined factors that may be related to and used to predict the elimination of DSA. The most significant associations have been strength of antibody at initiation of treatment and antibody specificity, although other factors revealed a trend toward association. We demonstrate how the types of data generated here can be used to predict elimination or persistence of DSA.  相似文献   
103.
104.

Background

There is growing interest in telehealth—the use of technology to support the remote delivery of health care and promote self-management—as a potential alternative to face-to-face care for patients with chronic diseases. However, little is known about what precipitates interest in the use of telehealth among these patients.

Objective

This survey forms part of a research program to develop and evaluate a telehealth intervention for patients with two exemplar chronic diseases: depression and raised cardiovascular disease (CVD) risk. The survey was designed to explore the key factors that influence interest in using telehealth in these patient groups.

Methods

Thirty-four general practices were recruited from two different regions within England. Practice records were searched for patients with (1) depression (aged 18+ years) or (2) 10-year risk of CVD ≥20% and at least one modifiable risk factor (aged 40-74 years). Within each general practice, 54 patients in each chronic disease group were randomly selected to receive a postal questionnaire. Questions assessed five key constructs: sociodemographics, health needs, difficulties accessing health care, technology-related factors (availability, confidence using technology, perceived benefits and drawbacks of telehealth), and satisfaction with prior use of telehealth. Respondents also rated their interest in using different technologies for telehealth (phone, email and Internet, or social media). Relationships between the key constructs and interest in using the three mediums of telehealth were examined using multivariable regression models.

Results

Of the 3329 patients who were sent a study questionnaire, 44.40% completed it (872/1740, 50.11% CVD risk; 606/1589, 38.14% depression). Overall, there was moderate interest in using phone-based (854/1423, 60.01%) and email/Internet-based (816/1425, 57.26%) telehealth, but very little interest in social media (243/1430, 16.99%). After adjusting for health needs, access difficulties, technology-related factors, and prior use of telehealth, interest in telehealth had largely no association with sociodemographic variables. For both patient groups and for each of the three technology mediums, the most important constructs related to interest in telehealth were having the confidence to use the associated technology, as well as perceiving greater advantages and fewer disadvantages from using telehealth. To illustrate, greater confidence using phone technologies (b=.16, 95% CI 0.002-0.33), while also perceiving more benefits (b=.31, 95% CI 0.21-0.40) and fewer drawbacks (b=-.23, 95% CI -0.28 to -0.17) to using telehealth were associated with more interest in using phone-based telehealth technologies for patients with depression.

Conclusions

There is widespread interest in using phone-based and email/Internet-based telehealth among patients with chronic diseases, regardless of their health status, access difficulties, age, or many other sociodemographic factors. This interest could be increased by helping patients gain confidence using technologies and through highlighting benefits and addressing concerns about telehealth. While the same pattern exists for social media telehealth, interest in using these technologies is minimal.  相似文献   
105.
Recombinant severe acute respiratory syndrome (SARS) nucleocapsid and spike protein-based immunoglobulin G immunoassays were developed and evaluated. Our assays demonstrated high sensitivity and specificity to the SARS coronavirus in sera collected from patients as late as 2 years postonset of symptoms. These assays will be useful not only for routine SARS coronavirus diagnostics but also for epidemiological and antibody kinetic studies.  相似文献   
106.
FT Chew  DYT Goh  BC Ooi  R Saharom  JKS Hui  BW Lee 《Allergy》1999,54(4):320-329
BACKGROUND: Air-pollution levels have been shown to be associated with increased morbidity of respiratory diseases. METHODS: Data for ambient air-pollutant levels, meteorologic factors, and hospitalization or emergency room (ER) visits for acute asthma in Singapore children over a 5-year period (1990-4) were obtained and analyzed for associations by time-series methods. RESULTS: Throughout this period, the annual mean and 24-h mean levels for sulfur dioxide (SO2), nitrogen dioxide (NO2), and total suspended particles (TSP) and maximum 1-h daily average for ozone were generally within the air-quality guidelines established by the World Health Organization (WHO). However, positive correlation between levels of each of these pollutants and daily ER visits for asthma was observed in children aged 3-12 years, but not among adolescents and young adults (13-21 years old). The association with SO2 and TSP persisted after standardization for meteorologic and temporal variables. An adjusted increase in 2.9 ER visits for every 20 microg/m3 increase in atmospheric SO2 levels, lagged by 1 day, was observed on days when levels were above 68 microg/m3. With TSP, an adjusted increase of 5.80 ER visits for every 20 microg/m3 increase in its daily atmospheric levels, lagged by 1 day, was observed on days with levels above 73 microg/m3. Similar results were also obtained after controlling for autocorrelation by time-series analysis. CONCLUSIONS: These associations were observed even though the overall levels of all pollutants were generally within the air-quality guidelines established by the WHO. These findings suggest that asthmatic children are susceptible to increased levels of air pollutants, particularly SO2 and TSP, although the ambient levels are generally within "acceptable" ranges.  相似文献   
107.
Stakeholders engaged in funding health programs and investing in human capital are concerned that their investments lead to beneficial long-term outcomes and do not fade from existence when funding streams dry up. However, dissemination and implementation researchers often pay little attention to what happens after programs are implemented. An essential function of the public health nurse operating at the executive management or leadership level is to evaluate overall effectiveness, quality, and sustainability of programs and to design systems-level quality initiatives and evaluation plans that foster program sustainability. This article applies a conceptual framework for sustainability to an oral health program serving persons experiencing homelessness, exploring the essential programmatic, community, and organizational factors that have positively impacted the long-term sustainability of the program. Lessons learned from a model program that has thrived in a political and economic resource poor climate may assist the public health nurse in planning and developing health programs that can withstand the test of time even in the most challenging of circumstances.  相似文献   
108.
109.
BACKGROUND: To date, relatively few representative data have been available to health planners and advocacy groups on the life expectancy of people with intellectual disability. A study of trends in the survival profiles of people with intellectual disability was undertaken to assist in the planning of appropriate medical and support services. METHODS: Since 1953, the Disability Services Commission of Western Australia has maintained a database of persons diagnosed with intellectual disability. The database was used to calculate survival probabilities on a total of 8724 individuals, 7562 of whom were still alive at the time of sampling in December 2000. RESULTS: Kaplan-Meier survival plots showed a strong negative association between severity of intellectual disability and survival, with median life expectancies of 74.0, 67.6, and 58.6 years for people with mild, moderate, and severe levels of handicap. Significant negative associations also were observed with male gender, Indigenous Australian parentage, and individuals diagnosed with a specific genetic disorder. CONCLUSIONS: The findings indicate a major and expanding increase in the service requirements of this aging, intellectually disabled population during the past two generations.  相似文献   
110.
OBJECTIVES: The objective of this study was to determine whether diastolic dysfunction is associated with increased risk of nonvalvular atrial fibrillation (NVAF) in older adults with no history of atrial arrhythmia. BACKGROUND: Few data exist regarding the relationship between diastolic function and NVAF. METHODS: The clinical and echocardiographic characteristics of patients age > or =65 years who had an echocardiogram performed between 1990 and 1998 were reviewed. Exclusion criteria were history of atrial arrhythmia, stroke, valvular or congenital heart disease, or pacemaker implantation. Patients were followed up in their medical records to the last clinical visit or death for documentation of first AF. RESULTS: Of 840 patients (39% men; mean [+/- SD] age, 75 +/- 7 years), 80 (9.5%) developed NVAF over a mean (+/- SD) follow-up of 4.1 +/- 2.7 years. Abnormal relaxation, pseudonormal, and restrictive left ventricular diastolic filling were associated with hazard ratios of 3.33 (95% confidence interval [CI], 1.5 to 7.4; p = 0.003), 4.84 (95% CI, 2.05 to 11.4; p < 0.001), and 5.26 (95% CI, 2.3 to 12.03; p < 0.001), respectively, when compared with normal diastolic function. After a number of adjustments, diastolic function profile remained incremental to history of congestive heart failure and previous myocardial infarction for prediction of NVAF. Age-adjusted Kaplan-Meier five-year risks of NVAF were 1%, 12%, 14%, and 21% for normal, abnormal relaxation, pseudonormal, and restrictive diastolic filling, respectively. CONCLUSIONS; The presence and severity of diastolic dysfunction are independently predictive of first documented NVAF in the elderly.  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