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   7944篇
  免费   616篇
  国内免费   36篇
耳鼻咽喉   45篇
儿科学   344篇
妇产科学   234篇
基础医学   1147篇
口腔科学   83篇
临床医学   1120篇
内科学   1418篇
皮肤病学   187篇
神经病学   888篇
特种医学   152篇
外科学   724篇
综合类   72篇
一般理论   12篇
预防医学   989篇
眼科学   95篇
药学   455篇
中国医学   3篇
肿瘤学   628篇
  2023年   46篇
  2022年   74篇
  2021年   175篇
  2020年   115篇
  2019年   182篇
  2018年   196篇
  2017年   154篇
  2016年   159篇
  2015年   174篇
  2014年   267篇
  2013年   498篇
  2012年   578篇
  2011年   587篇
  2010年   341篇
  2009年   310篇
  2008年   496篇
  2007年   589篇
  2006年   507篇
  2005年   461篇
  2004年   438篇
  2003年   416篇
  2002年   383篇
  2001年   60篇
  2000年   41篇
  1999年   74篇
  1998年   94篇
  1997年   87篇
  1996年   68篇
  1995年   69篇
  1994年   60篇
  1993年   40篇
  1992年   49篇
  1991年   33篇
  1990年   36篇
  1989年   50篇
  1988年   47篇
  1987年   47篇
  1986年   44篇
  1985年   46篇
  1984年   46篇
  1983年   40篇
  1982年   43篇
  1981年   39篇
  1980年   35篇
  1979年   17篇
  1977年   20篇
  1976年   18篇
  1975年   17篇
  1974年   21篇
  1973年   22篇
排序方式: 共有8596条查询结果,搜索用时 15 毫秒
921.
At its 2011 conference in Nice, France, the European General Practice Research Network (EGPRN), considered the issue of Relevant Outcome Measures in General Practice Research into Chronic Diseases. This paper, which is adapted from a keynote lecture given during that conference, considers the role of qualitative outcome assessments in research. Such assessments have a great deal in common with the patient-centred approach of general practice as they can capture the overall state of a patient rather than capturing only certain aspects. Research suggests that patients can be categorized, based on qualitative outcome assessment, and over time might change category. This approach to assessment brings to our attention alternative ways of considering the future: future as currently being made or future as predictable, at least to some extent. Although general practice needs the evidence from research that predicts the future, it also needs to engage in research that seeks to understand patients as they make their future, and to understand the impact of clinical interventions on this process.  相似文献   
922.
A cost-effectiveness analysis was conducted in screening for breast cancer. The use of conventional mammography, digital and magnetic resonance imaging were compared with natural disease history as a baseline. A Markov model projected breast cancer in a group of 100,000 women for a 30 year period, with screening every two years. Four distinct scenarios were modeled: (1) the natural history of breast cancer, as a baseline, (2) conventional film mammography, (3) digital mammography and (4) magnetic resonance imaging. The costs of the scenarios modeled ranged from R$ 194.216,68 for natural history, to R$ 48.614.338,31, for screening with magnetic resonance imaging. The difference in effectiveness between the interventions ranged from 300 to 78.000 years of life gained in the cohort. The ratio of incremental cost-effectiveness in terms of cost per life-year gains, conventional mammographic screening has produced an extra year for R$ 13.573,07. The ICER of magnetic resonance imaging was R$ 2.904.328,88, compared to no screening. In conclusion, it is more cost-effective to perform the screening with conventional mammography than other technological interventions.  相似文献   
923.
ABSTRACT: BACKGROUND: Published incidence rates of human salmonella infections are mostly based on numbers of stool culture-confirmed cases reported to public health surveillance. These cases constitute only a small fraction of all cases occurring in the community. The extend of underascertainment is influenced by health care seeking behaviour and sensitivity of surveillance systems, so that reported incidence rates from different countries are not comparable. We performed serological cross-sectional studies to compare infection risks in eight European countries independent of underascertainment. METHODS: A total of 6,393 sera, mostly from existing serum collections representative of the adult population in Denmark, Finland, France, Italy, Poland, Romania, Sweden, and The Netherlands were analyzed. Immunoglobulin A (IgA), IgM, and IgG against salmonella lipopolysaccharides were measured by in-house mixed ELISA. We converted antibody concentrations to estimates of infection incidence ('sero-incidence') using a Bayesian backcalculation model, based on previously studied antibody decay profiles in persons with culture-confirmed salmonella infections. We compared sero-incidence with incidence of cases reported through routine public health surveillance and with published incidence estimates derived from infection risks in Swedish travellers to those countries. RESULTS: Sero-incidence of salmonella infections ranged from 56 (95% credible interval 8-151) infections per 1,000 person-years in Finland to 547 (343-813) in Poland. Depending on country, sero-incidence was approximately 100 to 2,000 times higher than incidence of culture-confirmed cases reported through routine surveillance, with a trend for an inverse correlation. Sero-incidence was significantly correlated with incidence estimated from infection risks in Swedish travellers. CONCLUSIONS: Sero-incidence estimation is a new method to estimate and compare the incidence of salmonella infections in human populations independent of surveillance artefacts. Our results confirm that comparison of reported incidence between countries can be grossly misleading, even within the European Union. Because sero-incidence includes asymptomatic infections, it is not a direct measure of burden of illness. But, pending further validation, it is a promising and cost-effective approach to assess infection risks and to evaluate the effectiveness of salmonella control programmes across countries.  相似文献   
924.
925.
926.
PurposeOxidative damage has been implicated in carcinogenesis. We hypothesized that elevated systemic oxidative status would be associated with later occurrence of colorectal adenomatous polyps, a precursor of colorectal cancer.MethodsWe examined the prospective association between four systemic markers of oxidative status and colorectal adenomatous polyps within a nondiabetic subcohort of the Insulin Resistance Atherosclerosis Study (n = 425). Urine samples were collected from 1992 to 1994 and colorectal adenomas prevalence were assessed in 2002 to 2004. Oxidative status markers were assessed, which included four F2-isoprostanes (F2-IsoPs) from the classes III and IV: iPF2α-III, 2,3-dinor-iPF2α-III (a metabolite of iPF2α-III), iPF2α-VI, and 8,12-iso-iPF2α-VI. All biomarkers were quantified using liquid chromatography–tandem mass spectrometry. Prospective associations were assessed using multivariate logistic regression analysis.ResultsThe adjusted odds ratio (OR) (95% confidence interval [CI]) for occurrence of colorectal adenomatous polyps and scaled to 1 SD of F2-IsoP distribution were 1.16 (95% CI, 0.88–1.50), 0.88 (95% CI, 0.63–1.17), 1.04 (95% CI, 0.80–1.34), and 1.16 (95% CI, 0.90–1.48) for iPF2α-III, iPF2α-VI, 8,12-iso-iPF2α-VI, and 2,3-dinor-iPF2α-III, respectively.ConclusionsThe lack of association between F2-IsoPs and adenomatous polyps does not support the hypothesis that elevated oxidative status is associated with colorectal adenomatous polyp occurrence during a 10-year period of follow-up.  相似文献   
927.
928.
Laboratory testing by clinicians is essential to outbreak investigations. Electronic health records may increase testing through clinical decision support that alerts providers about existing outbreaks and facilitates laboratory ordering. The impact on laboratory testing was evaluated for foodborne disease outbreaks between 2006 and 2009. After controlling for standard public health messaging and season, decision support resulted in a significant increase in laboratory testing and may be useful in enhancing public health messaging and provider action.  相似文献   
929.
We analyzed travel-associated clinical isolates of Escherichia coli O104:H4, including 1 from the 2011 German outbreak and 1 from a patient who returned from the Philippines in 2010, by genome sequencing and optical mapping. Despite extensive genomic similarity between these strains, key differences included the distribution of toxin and antimicrobial drug-resistance determinants.  相似文献   
930.
Epizootic pneumonia of bighorn sheep is a devastating disease of uncertain etiology. To help clarify the etiology, we used culture and culture-independent methods to compare the prevalence of the bacterial respiratory pathogens Mannheimia haemolytica, Bibersteinia trehalosi, Pasteurella multocida, and Mycoplasma ovipneumoniae in lung tissue from 44 bighorn sheep from herds affected by 8 outbreaks in the western United States. M. ovipneumoniae, the only agent detected at significantly higher prevalence in animals from outbreaks (95%) than in animals from unaffected healthy populations (0%), was the most consistently detected agent and the only agent that exhibited single strain types within each outbreak. The other respiratory pathogens were frequently but inconsistently detected, as were several obligate anaerobic bacterial species, all of which might represent secondary or opportunistic infections that could contribute to disease severity. These data provide evidence that M. ovipneumoniae plays a primary role in the etiology of epizootic pneumonia of bighorn sheep.  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