全文获取类型
收费全文 | 7214篇 |
免费 | 647篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 48篇 |
儿科学 | 153篇 |
妇产科学 | 468篇 |
基础医学 | 1102篇 |
口腔科学 | 509篇 |
临床医学 | 1279篇 |
内科学 | 1164篇 |
皮肤病学 | 188篇 |
神经病学 | 525篇 |
特种医学 | 322篇 |
外科学 | 758篇 |
综合类 | 89篇 |
一般理论 | 8篇 |
预防医学 | 516篇 |
眼科学 | 113篇 |
药学 | 338篇 |
中国医学 | 22篇 |
肿瘤学 | 283篇 |
出版年
2023年 | 85篇 |
2022年 | 92篇 |
2021年 | 171篇 |
2020年 | 143篇 |
2019年 | 157篇 |
2018年 | 234篇 |
2017年 | 199篇 |
2016年 | 232篇 |
2015年 | 252篇 |
2014年 | 303篇 |
2013年 | 380篇 |
2012年 | 408篇 |
2011年 | 474篇 |
2010年 | 333篇 |
2009年 | 316篇 |
2008年 | 395篇 |
2007年 | 380篇 |
2006年 | 286篇 |
2005年 | 224篇 |
2004年 | 244篇 |
2003年 | 217篇 |
2002年 | 189篇 |
2001年 | 190篇 |
2000年 | 155篇 |
1999年 | 151篇 |
1998年 | 122篇 |
1997年 | 125篇 |
1996年 | 130篇 |
1995年 | 105篇 |
1994年 | 84篇 |
1993年 | 62篇 |
1992年 | 67篇 |
1991年 | 65篇 |
1990年 | 50篇 |
1989年 | 60篇 |
1988年 | 77篇 |
1987年 | 49篇 |
1986年 | 65篇 |
1985年 | 69篇 |
1984年 | 34篇 |
1983年 | 42篇 |
1982年 | 38篇 |
1981年 | 32篇 |
1980年 | 31篇 |
1979年 | 26篇 |
1978年 | 28篇 |
1977年 | 30篇 |
1975年 | 35篇 |
1971年 | 22篇 |
1970年 | 30篇 |
排序方式: 共有7885条查询结果,搜索用时 15 毫秒
101.
Julian Jakob Roman von Wyl Odile Stalder Mark J. Pletcher Eric Vittinghoff Kali Tal Jamal S. Rana Stephen Sidney Jared P. Reis Reto Auer 《The American journal of medicine》2021,134(6):777-787.e9
BackgroundLong-term cardiovascular health effects of marijuana are understudied. Future cardiovascular disease is often indicated by subclinical atherosclerosis for which carotid intima-media thickness is an established parameter.MethodsUsing the data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, a cohort of 5115 Black and white women and men at Year 20 visit, we studied the association between carotid intima-media thickness in midlife and lifetime exposure to marijuana (1 marijuana year = 365 days of use) and tobacco smoking (1 pack-year = 20 cigarettes/day for 365 days). We measured carotid intima-media thickness by ultrasound and defined high carotid intima-media thickness at the threshold of the 75th percentile of all examined participants. We fit logistic regression models stratified by tobacco smoking exposure, adjusting for demographics, cardiovascular risk factors, and other drug exposures.ResultsData was complete for 3257 participants; 2722 (84%) reported ever marijuana use; 374 (11%) were current users; 1539 (47%) reported ever tobacco smoking; 610 (19%) were current smokers. Multivariable adjusted models showed no association between cumulative marijuana exposure and high carotid intima-media thickness in never or ever tobacco smokers, odds ratio (OR) 0.87 (95% confidence interval [CI]: 0.63-1.21) at 1 marijuana-year among never smokers and OR 1.11 (95% CI: 0.85-1.45) among ever tobacco smokers. Cumulative exposure to tobacco was strongly associated with high carotid intima-media thickness, OR 1.88 (95%CI: 1.20-2.94) for 20 pack-years of exposure.ConclusionsThis study adds to the growing body of evidence that there might be no association between the average population level of marijuana use and subclinical atherosclerosis. 相似文献
102.
Vernica Frana Diniz Rocha Thiago Pereira Cavalcanti Jailton Azevedo Helena Ferreira Leal Giulyana Evelyn Oliveira Silva Allan Roberto Xavier Malheiros Ledilce Almeida Ataide Jos Admiro Lima Filho Antonio Raimundo Pinto Almeida Nadia de Andrade Khouri Mitermayer Galvo Reis Joice Neves Reis 《The American journal of tropical medicine and hygiene》2021,104(3):848
103.
104.
Narjara Campos de Araújo Orivaldo Florêncio de Souza Mauro Jos de Deus Morais Francisco Naildo Cardoso Leito Italla Maria Pinheiro Bezerra Luiz Carlos de Abreu Luciano Miller Reis Rodrigues 《Medicine》2021,100(16)
Musculoskeletal disorders gradually affect workers in different parts of the world, compromising their occupational health and quality of life. Professionals exposed to these symptoms include the motorcycle taxi driver, whose pain is due to the overuse of the musculoskeletal system and little time to recover it.To identify the prevalence of musculoskeletal symptoms in motorcycle taxi drivers in the city of Rio Branco, Acre, Brazil, West Amazon.Cross-sectional study, involving 296 motorcycle taxi drivers in the city of Rio Branco-Acre, Brazil, male, from December 2016 to February 2017. The Nordic Musculoskeletal Questionnaire was used to collect information related to symptoms (pain, discomfort, or numbness) in the last 7 days of work. For the exclusion criteria were, being female; not reside outside the city of Rio Branco, Acre; having less than 3 months of work activity; not be carrying out their work activities at the time of application of the protocol; be limited by clinical or physical issues at the time of application of the protocol. The data obtained in the questionnaire were entered into the Epidata program (Epidata Association, Odense, Denmark) and then transferred to the STATA 10 statistical program (Stata Corp., College Station), for categorization and statistical analysis.The study population is over 36 years old; most reported having a partner and a higher education level. The average daily working hours of the participants were 12 hours, with the majority working over 12 hours daily. Most of the epidemiological variables factors were associated with musculoskeletal pain when the prevalence and prevalence ratio analyzes were performed. Higher prevalence of musculoskeletal symptoms in the lumbar region is with 17.9%. In the lower limbs, the most affected joint was the ankle (5.7%), followed by the hip (5.07%) and knee (5.07%), respectively. Insomnia was present in 55.35% and self-reported headache in 49.4% of participants.The musculoskeletal disorders generated by the daily service of motorcycle taxi drivers are directly affecting the quality of life of these professionals. 相似文献
105.
Thiago Magalh?es da Silva M R Sandhya Rani Gustavo Nunes de Oliveira Costa Maria A Figueiredo Paulo S Melo Jo?o F Nascimento Neil D Molyneaux Maurício L Barreto Mitermayer G Reis M Glória Teixeira Ronald E Blanton 《European journal of human genetics : EJHG》2015,23(7):984-989
The degree of admixture in Brazil between historically isolated populations is complex and geographically variable. Studies differ as to what the genetic and phenotypic consequences of this mixing have been. In Northeastern Brazil, we enrolled 522 residents of Salvador and 620 of Fortaleza whose distributions of self-declared color were comparable to those in the national census. Using the program Structure and principal components analysis there was a clear correlation between biogeographic ancestry and categories of skin color. This correlation with African ancestry was stronger in Salvador (r=0.585; P<0.001) than in Fortaleza (r=0.236; P<0.001). In Fortaleza, although self-declared blacks had a greater proportion of European ancestry, they had more African ancestry than the other categories. When the populations were analyzed without pseudoancestors, as in some studies, the relationship of ‘race'' to genetic ancestry tended to diffuse or disappear. The inclusion of different African populations also influenced ancestry estimates. The percentage of unlinked ancestry informative markers in linkage disequilibrium, a measure of population structure, was 3–5 times higher in both Brazilian populations than expected by chance. We propose that certain methods, ascertainment bias and population history of the specific populations surveyed can result in failure to demonstrate a correlation between skin color and genetic ancestry. Population structure in Brazil has important implications for genetic studies, but genetic ancestry is irrelevant for how individuals are treated in society, their health, their income or their inclusion. These track more closely with perceived skin color than genetic ancestry. 相似文献
106.
Dziennis S; Van Etten RA; Pahl HL; Morris DL; Rothstein TL; Blosch CM; Perlmutter RM; Tenen DG 《Blood》1995,85(2):319-329
CD11b is the alpha chain of the Mac-1 integrin and is preferentially expressed in myeloid cells (neutrophils, monocytes, and macrophages). We have previously shown that the CD11b promoter directs cell-type- specific expression in myeloid lines using transient transfection assays. To confirm that these promoter sequences contain the proper regulatory elements for correct myeloid expression of CD11b in vivo, we have used the -1.7-kb human CD11b promoter to direct reporter gene expression in transgenic mice. Stable founder lines were generated with two different reporter genes, a Thy 1.1 surface marker and the Escherichia coli lacZ (beta-galactosidase) gene. Analysis of founders generated with each reporter demonstrated that the CD11b promoter was capable of driving high levels of transgene expression in murine macrophages for the lifetime of the animals. Similar to the endogenous gene, transgene expression was preferentially found in mature monocytes, macrophages, and neutrophils and not in myeloid precursors. These experiments indicate that the -1.7 CD11b promoter contains the regulatory elements sufficient for high-level macrophage expression. This promoter should be useful for targeting heterologous gene expression to mature myeloid cells. 相似文献
107.
Reis EA Athanazio DA McBride AJ Azevedo TM Magalhães-Santos IF Harn D Reis MG 《Acta tropica》2008,108(2-3):131-134
We previously reported the association of the major histocompatibility complex class II HLA-DQB1*0201 allele with hepatosplenic schistosomiasis. The aim of this study was to evaluate the cytokine responses of peripheral blood mononuclear cells (PBMCs) and the serum levels of immunoglobulin isotypes. The study population was selected from a schistosomiasis endemic area. No significant differences in cytokine profiles were detected in PBMCs stimulated with Schistosoma mansoni soluble egg antigen (SEA), regardless of the subjects DQB1*0201 genotype or infection status. However, previously infected DQB1*0201 positive individuals had significantly lower levels of IgG4 compared to DQB1*0201 negative individuals (P<0.05). 相似文献
108.
Harriet Chan-Myers BS RM David McAlister PhD ABMM Patricia Antonoplos PhD 《American journal of infection control》1997,25(6):471-476
Controversy exists concerning the degree of microbial contamination associated with the us of rigid lumened medical devices, the efficacy of standard cleaning techniques used to remove pathogenic microorganisms from lumen channels, and whether patients are placed at risk of cross infection because of microbial contamination. In this study the level and types of microorganisms found on rigid lumened medical devices before and after cleaning in a hospital environment were investigated. The bioburden level after clinical use was found to be relatively low, ranging from 101 to 104 colony forming units (CFU) per device. After the instruments were cleaned, none of the devices studied contained bioburden levels greater than 104 CFU and 83% had bioburden levels less than or equal to 102 CFU. The bioburden present before cleaning was comprised of organisms derived from the handling of the device, from the hospital environment, and from the patient. The bioburden present after cleaning was comprised of organisms typically derived from the handling of the device and from the hospital environment. The level of bioburden per device was also related to the anatomic site where the device was used, with lower numbers of organisms found on devices exposed to sterile body sites and the respiratory tract. 相似文献
109.
A feasibility study on using tablet personal computers for self‐reported symptom assessment in newly diagnosed lung cancer patients 下载免费PDF全文