全文获取类型
收费全文 | 9273篇 |
免费 | 634篇 |
国内免费 | 66篇 |
专业分类
耳鼻咽喉 | 65篇 |
儿科学 | 222篇 |
妇产科学 | 200篇 |
基础医学 | 1595篇 |
口腔科学 | 124篇 |
临床医学 | 916篇 |
内科学 | 2346篇 |
皮肤病学 | 127篇 |
神经病学 | 832篇 |
特种医学 | 185篇 |
外科学 | 770篇 |
综合类 | 44篇 |
一般理论 | 1篇 |
预防医学 | 819篇 |
眼科学 | 143篇 |
药学 | 775篇 |
中国医学 | 29篇 |
肿瘤学 | 780篇 |
出版年
2024年 | 11篇 |
2023年 | 117篇 |
2022年 | 264篇 |
2021年 | 406篇 |
2020年 | 208篇 |
2019年 | 280篇 |
2018年 | 327篇 |
2017年 | 243篇 |
2016年 | 233篇 |
2015年 | 326篇 |
2014年 | 366篇 |
2013年 | 516篇 |
2012年 | 737篇 |
2011年 | 746篇 |
2010年 | 399篇 |
2009年 | 384篇 |
2008年 | 620篇 |
2007年 | 665篇 |
2006年 | 595篇 |
2005年 | 546篇 |
2004年 | 444篇 |
2003年 | 445篇 |
2002年 | 397篇 |
2001年 | 27篇 |
2000年 | 45篇 |
1999年 | 60篇 |
1998年 | 76篇 |
1997年 | 52篇 |
1996年 | 36篇 |
1995年 | 23篇 |
1994年 | 12篇 |
1993年 | 18篇 |
1992年 | 12篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 17篇 |
1988年 | 22篇 |
1987年 | 16篇 |
1986年 | 15篇 |
1985年 | 20篇 |
1984年 | 12篇 |
1982年 | 9篇 |
1981年 | 22篇 |
1980年 | 10篇 |
1978年 | 14篇 |
1977年 | 13篇 |
1975年 | 8篇 |
1974年 | 11篇 |
1972年 | 8篇 |
1971年 | 8篇 |
排序方式: 共有9973条查询结果,搜索用时 15 毫秒
991.
Periannular extension of infective endocarditis 总被引:5,自引:0,他引:5
Graupner C Vilacosta I SanRomán J Ronderos R Sarriá C Fernández C Mújica R Sanz O Sanmartín JV Pinto AG 《Journal of the American College of Cardiology》2002,39(7):1204-1211
OBJECTIVES: This prospective study was designed to assess the current clinical course, risk factors, microbiologic profile and echocardiographic findings of patients with left-sided endocarditis and perivalvular complications. BACKGROUND: Periannular complications worsen the prognosis of patients with endocarditis. The relation between these complications and the clinical and microbiologic data has not been clearly defined. METHODS: In this clinical cohort study, 211 patients with left-sided endocarditis, according to the Duke criteria, were prospectively recruited. All patients underwent conventional and transesophageal echocardiography. The mean follow-up interval was 151 days. RESULTS: Perivalvular complications were detected in 78 patients (37%). The incidence of periannular extension of infection in native and prosthetic valves was 29% and 55%, respectively. The presence of prosthesis (relative risk [RR] 1.88, 95% confidence interval [CI] 1.35 to 2.64) and previous endocarditis (RR 1.78, 95% CI 1.16 to 2.7) were the only pre-existing heart conditions associated with perivalvular complications. Aortic infection (RR 1.8, 95% CI 1.23 to 2.66) and the development of atrioventricular (AV) block (RR 2.55, 95% CI 1.91 to 3.41) were related with the existence of these complications. Coagulase-negative staphylococci were very common in patients with perivalvular complications (RR 1.77, 95% CI 1.21 to 2.59), and small vegetations were more frequent in these patients (RR l.45, 95% CI 0.95 to 2.22). An operation was more frequently performed in patients with perivalvular complications, but mortality was similar in patients with and without these complications. CONCLUSIONS: Aortic infection, prosthetic endocarditis, new AV block and coagulase-negative staphylococci were independent risk factors of periannular complications. The period between symptom onset and diagnosis, the incidence of pericardial effusion and persistent signs of infection were similar between patients with and without perivalvular complications. Patients with perivalvular complications did not demonstrate a difference in the presence or size of vegetations or the frequency of embolism. An operation was more frequently performed in these patients, but mortality was similar in both groups. 相似文献
992.
Angel Vila-Corcoles Olga Ochoa-Gondar Jorge A Guzmán Teresa Rodriguez-Blanco Elisabet Salsench Cruz M Fuentes EPIVAC Study Group 《BMC infectious diseases》2010,10(1):73
Background
The 23-valent polysaccharide pneumococcal vaccine (PPV) is currently recommended in elderly and high-risk adults. However, its efficacy in preventing pneumococcal infections remains controversial. This study assessed the clinical effectiveness of vaccination against invasive pneumococcal disease (IPD) among people over 60 years. 相似文献993.
Lauretta E. Grau Edward White Linda M. Niccolai Olga V. Toussova Sergei V. Verevochkin Andrei P. Kozlov Robert Heimer 《AIDS and behavior》2011,15(1):45-57
We examined the prevalence of HIV disclosure to sexual partners by HIV-positive drug injectors (IDUs) in St. Petersburg, Russia
and compared the magnitude and direction of associations of condom use with awareness of one’s HIV infection and disclosure
to partners. Among 157 HIV-infected participants, awareness of infection at time of last intercourse was associated with condom
use with partners perceived to be HIV-negative (aOR 6.68, 95% CI 1.60–27.88). Among the 70 participants aware of their infection
prior to enrolment, disclosure to potentially uninfected sexual partners was independently and negatively associated with
condom use (aOR 0.13, 95% CI 0.02–0.66). Disclosure was independently associated with having injected ≥9 years (aOR 6.04,
95% CI 1.53–23.77) and partnership with another IDU (aOR 3.61, 95% CI 1.44–9.06) or HIV-seropositive (aOR 45.12, 95% CI 2.79–730.46).
Scaling up HIV testing services and interventions that increase the likelihood of individuals receiving their test results
is recommended. 相似文献
994.
Olga Grinstead Reznick Megan Comfort Kathleen McCartney Torsten B. Neilands 《AIDS and behavior》2011,15(2):365-375
Having an incarcerated partner presents a unique HIV risk for women, particularly low-income women of color. We developed
a population-specific risk reduction intervention for women visiting men in prison that was peer educator-based and included
individual and community-level intervention components. Women who were assessed prior to the intervention period had a positive
association between the number of unprotected penetrative intercourse (UPI) episodes prior to their partners’ incarceration
and the number of UPI episodes following partners’ release from prison. However, this association was negated among women
assessed during the intervention. Intervention participants also were more likely to be tested for HIV, to have partners who
got tested, and to talk with their partners about significantly more HIV-related topics. Conducting intervention and evaluation
activities with women visiting incarcerated men is feasible and is a useful model for reaching more at-risk women. 相似文献
995.
Claudio Puoti Lia Bellis Riccardo Guarisco Orlando Dell' Unto Lucia Spilabotti Olga Mitidieri Costanza 《European Journal of Internal Medicine》2010,21(2):57-61
Approximately 30% of patients with chronic HCV infection show persistently normal ALT levels. Although formerly referred to as ‘healthy’ or ‘asymptomatic’ HCV carriers, and thus historically excluded from antiviral treatment, it has now become clear that the majority of these patients have some degree of histological liver damage that may be significant in up to 20% of patients and might progress toward a more severe degree of liver fibrosis. A significant proportion of patients (≥ 20%) experience periods of increased serum ALT (flare) associated with enhanced disease progression. However, controversies still exist in clinical practice regarding the definition of ‘persistent’ ALT normality, the virological and histological features of these subjects, the need for liver biopsy, the role of non invasive tools for the assessment of liver fibrosis (transient hepatic elastography, fibroscan), and the natural history and optimal management of chronic hepatitis C with normal ALT. The advent of new therapeutic options (pegylated interferons plus ribavirin) has shifted treatment targets toward eradication of underlying infection, with therapy decision based on age, severity of disease and likelihood of response rather than on aminotransferase levels. This review does approach the main unresolved issues on this topic in the form of a dialog between a hepatologist and a patient with HCV infection but normal alanine aminotransferase levels, trying to give evidence-based answers to the more frequently asked questions from patients and their physicians. 相似文献
996.
We would like to present a case of patient with a transudative pleural effusion as a result of atherosclerotic occlusion of renal arteries. About 50 liters of fluid were drained from the right pleural cavity during 10 months period of observation. Successful revascularization of kidneys improved left ventricular function, stabilized hemodynamic of the pulmonary circulation and thus led to elimination of pleural effusion. 相似文献
997.
Yuan W Sørensen HT Basso O Olsen J 《Alcoholism, clinical and experimental research》2004,28(5):765-768
BACKGROUND: Asthma may have a prenatal origin. We examined whether maternal alcohol consumption during pregnancy increases the risk of hospitalization with asthma in children. METHODS: We conducted a follow-up study on 10,440 singletons born at approximately 36 weeks of gestation or later to mothers attending midwife centers between April 1984 and April 1987 in Denmark. The mothers completed a questionnaire regarding lifestyle and socioeconomic factors, including alcohol consumption. The children were followed up through the Danish Hospital Discharge Registry. We determined the first hospitalization with a discharge diagnosis of asthma as recorded in the Danish Hospital Discharge Registry. RESULTS: Most pregnant women (81.5%) drank at least some alcohol during pregnancy, but only a few (2.1%) consumed 120 g or more per week. In total, 307 children were hospitalized at least once with a discharge diagnosis of asthma during follow-up (the cumulative incidence risk was 3.5% from birth to 12 years of age or the end of follow-up). After adjusting for maternal socioeconomic factors, dietary components, and other lifestyle factors, children whose mothers drank alcohol during pregnancy did not have an increased risk of hospitalization with asthma compared with the children of mothers who reported no alcohol consumption during pregnancy (adjusted incidence rate ratio, 0.95; 95% confidence interval, 0.70-1.29). Further analyses showed no association with the dose and type of alcohol or with binge drinking. CONCLUSIONS: The study provides no support for a causal link between maternal alcohol intake during pregnancy and asthma in childhood. 相似文献
998.
999.
H H Ajamieh S Menéndez G Martínez-Sánchez E Candelario-Jalil L Re A Giuliani Olga Sonia León Fernández 《Liver international》2004,24(1):55-62
BACKGROUND: Many studies indicate that oxygen free-radical formation after reoxygenation of liver may initiate the cascade of hepatocellular injury. It has been demonstrated that controlled ozone administration may promote an oxidative preconditioning or adaptation to oxidative stress, preventing the damage induced by reactive oxygen species and protecting against liver ischaemia-reperfusion (I/R) injury. AIMS: In the present study, the effects of ozone oxidative preconditioning (OzoneOP) on nitric oxide (NO) generation and the cellular redox balance have been studied. Methods: Six groups of rats were classified as follows: (1). sham-operated; (2). sham-operated+l-NAME (N(omega)-nitro-l-arginine methyl ester); (3). I/R (ischaemia 90 min-reperfusion 90 min); (4). OzoneOP+I/R; (5). OzoneOP+l-NAME+I/R; and (6). l-NAME+I/R. The following parameters were measured: plasma transaminases (aspartate aminotransferase, alanine aminotransferase) as an index of hepatocellular injury; in homogenates of hepatic tissue: nitrate/nitrite as an index of NO production; superoxide dismutase (SOD), catalase (CAT) and glutathione levels as markers of endogenous antioxidant system; and finally malondialdehyde+4-hydroxyalkenals (MDA+4-HDA) and total hydroperoxides (TH) as indicators of oxidative stress. Results: A correspondence between liver damage and the increase of NO, CAT, TH, glutathione and MDA+4-HDA concentrations were observed just as a decrease of SOD activity. OzoneOP prevented and attenuated hepatic damage in I/R and OzoneOP+l-NAME+I/R, respectively, in close relation with the above-mentioned parameters. CONCLUSIONS: These results show that OzoneOP protected against liver I/R injury through mechanisms that promote a regulation of endogenous NO concentrations and maintenance of cellular redox balance. Ozone treatment may have important clinical implications, particularly in view of the increasing hepatic transplantation programs. 相似文献
1000.
While the amygdala historically has been implicated in emotional stimuli processing, recent data suggest a general role in parceling out the relevance of stimuli, regardless of their emotional properties. Using functional magnetic resonance imaging, we tested the relevance hypothesis by investigating human amygdala responses to emotionally neutral stimuli while manipulating their relevance. The task was operationalized as highly relevant if a subsequent opportunity to respond for a reward depended on response accuracy of the task, and less relevant if the reward opportunity was independent of task performance. A region of interest analysis revealed bilateral amygdala activations in response to the high relevance condition compared to the low relevance condition. An exploratory whole-brain analysis yielded robust similar results in bilateral ventral striatum. A subsequent functional connectivity analysis demonstrated increased connectivity between amygdala and ventral striatum for the highly relevant stimuli compared to the less relevant stimuli. These findings suggest that the amygdala's processing profile goes beyond detection of emotions per se, and directly support the proposed role in relevance detection. In addition, the findings suggest a close relationship between amygdala and ventral striatal activity when processing relevant stimuli. Thus, the results may indicate that human amygdala modulates ventral striatum activity and subsequent behaviors beyond that observed for emotional cues, to encompass a broader range of relevant stimuli. 相似文献