全文获取类型
收费全文 | 1059篇 |
免费 | 75篇 |
国内免费 | 17篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 81篇 |
妇产科学 | 9篇 |
基础医学 | 88篇 |
口腔科学 | 26篇 |
临床医学 | 73篇 |
内科学 | 184篇 |
皮肤病学 | 27篇 |
神经病学 | 21篇 |
特种医学 | 159篇 |
外科学 | 115篇 |
综合类 | 134篇 |
预防医学 | 68篇 |
眼科学 | 4篇 |
药学 | 53篇 |
中国医学 | 39篇 |
肿瘤学 | 67篇 |
出版年
2023年 | 8篇 |
2022年 | 16篇 |
2021年 | 25篇 |
2020年 | 20篇 |
2019年 | 15篇 |
2018年 | 20篇 |
2017年 | 14篇 |
2016年 | 19篇 |
2015年 | 27篇 |
2014年 | 42篇 |
2013年 | 39篇 |
2012年 | 45篇 |
2011年 | 46篇 |
2010年 | 73篇 |
2009年 | 63篇 |
2008年 | 27篇 |
2007年 | 31篇 |
2006年 | 44篇 |
2005年 | 32篇 |
2004年 | 21篇 |
2003年 | 28篇 |
2002年 | 14篇 |
2001年 | 15篇 |
2000年 | 10篇 |
1999年 | 18篇 |
1998年 | 45篇 |
1997年 | 59篇 |
1996年 | 51篇 |
1995年 | 38篇 |
1994年 | 32篇 |
1993年 | 31篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 23篇 |
1988年 | 19篇 |
1987年 | 17篇 |
1986年 | 16篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 2篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 3篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1958年 | 4篇 |
1957年 | 2篇 |
排序方式: 共有1151条查询结果,搜索用时 15 毫秒
71.
Recent reports have demonstrated that the HIV-1 transactivator protein,tat, induces apoptosis in T-lymphocyte cell lines, as well as in peripheral blood mononuclear cells, and stimulates a cascade
of events resulting in up-regulation of the potent immunosuppressive cytokine, transforming growth factor-β (TGF-β). In this
study we evaluated the ability of TGF-β to mediatetat induced apoptosis in T-lymphocyte cell lines. T-cells treated exogenously with either TGF-β1 or a combination of tat and
pan-specific TGF-β neutralizing antibodies showed little change in the amount of apoptosis. When treated with pan-specific
TGF-β neutralizing antibodies, Jurkat cells that stably expresstat protein (Jurkat-tat) showed only a modest decrease in apoptosis, while CEM-TART cells (CEM T-cells expressing both HIV-1tat andrev) demonstrated little change in the amount of apoptosis. In conclusion, we have demonstrated that TGF-β does not play a significant
role in mediatingtat induced T-cell apoptosis. 相似文献
72.
Commentary on acute renal failure in Asian region 总被引:1,自引:0,他引:1
73.
74.
Pisano ED Chiu YF Ni L Li Y Britt GG Johnson RE Burns B Cole E Kuzmiak C Koomen M Pavic D 《Academic radiology》2004,11(5):536-543
RATIONALE AND OBJECTIVES: To determine which factors affected the increase in average glandular dose recorded at the annual US Food and Drug Administration Mammography Quality Standards Act inspections of mammography equipment in North Carolina from 1997 to 2001. MATERIALS AND METHODS: Average glandular dose, HVL, kVp, ambient light, luminance, equipment age, processing speed, and system speed for every mammography unit at all facilities in the state were collected by state inspectors. A mixed-effect model was used to assess the average changes of glandular dose over time and to identify the factors associated with these changes. RESULTS: There was a statistically significant increase in the average glandular dose in North Carolina in 1999, 2000, and 2001 when compared with the baseline year of 1997. Factors that were statistically significantly linked to this effect were changes in kVp, processing speed, and system speed. CONCLUSION: Average glandular dose for mammography has recently increased in North Carolina. This change is likely caused by changes in screen-film products and processing techniques. 相似文献
75.
Jaber WA White RD Kuzmiak SA Boyle JM Natale A Apperson-Hansen C Thomas JD Asher CR 《The American journal of cardiology》2004,93(4):486-489
We sought to determine the potential use of recently introduced cardiac 3-dimensional computed tomography as an alternative to transesophageal echocardiography for examination of the left atrial appendage. Our data suggest that computed tomography is a potential alternative for assessing the anatomy of the left atrial appendage and for detecting thrombi. 相似文献
76.
Pavic D Koomen MA Kuzmiak CM Lee YH Pisano ED 《Technology in cancer research & treatment》2004,3(6):527-541
A review of the literature on the current applications of breast magnetic resonance imaging (MRI) indications, their rationale and their place in diagnosis and management of breast cancer was given. Contrast-enhanced breast MRI is developing as a valuable adjunct to mammography and sonography. Its high sensitivity for invasive breast cancer establishes its superiority in evaluation of multifocality/multicentricity, tumor response to neoadjuvant chemotherapy, detection of recurrence, and staging. Emerging applications include spectroscopy, usage of new contrast agents, and MRI-guided interventions, including noninvasive treatment of breast cancer. Its potential benefit in screening high-risk women has yet to be established with prospective studies, particularly with regard to false positive results. 相似文献
77.
输血和大多数临床治疗技术一样,存在着一定的风险,输血风险主要由免疫性输血风险和输血感染性风险两大类相关的安全问题。20世纪80年代开始,由于艾滋病的发现迫使输血相关的安全问题更进一步成为公众关注的焦点。随着输血用血医学的不断发展,在已经获得很好治疗效果的同时,如何更加科学的安全用血是挑战当今公共卫生事业发展的一项大课题。 相似文献
78.
PR Hunziker S Smith M Scherrer-Crosbie N Liel-Cohen RA Levine R Nesbitt SA Benton MH Picard 《Circulation》1999,99(5):1-6
Background--Currently, the reporting and archiving of echocardiographic data suffer from the difficulty of representing heart motion on printable 2-dimensional (2D) media. Methods and Results--We studied the capability of holography to integrate motion into 2D echocardiographic prints. Images of normal human hearts and of a variety of mitral valve function abnormalities (mitral valve prolapse, systolic anterior motion of the mitral leaflets, and obstruction of the mitral valve by a myxoma) were acquired digitally on standard echocardiographic machines. Images were processed into a data format suitable for holographic printing. Angularly multiplexed holograms were then printed on a prototype holographic "laser" printer, with integration of time in vertical parallax, so that heart motion became visible when the hologram was tilted up and down. The resulting holograms displayed the anatomy with the same resolution as the original acquisition and allowed detailed study of valve motion with side-by-side comparison of normal and abnormal findings. Comparison of standard echocardiographic measurements in original echo frames and corresponding hologram views showed an excellent correlation of both methods (P<0.0001, r2=0.979, mean bias=2.76 mm). In this feasibility study, both 2D and 3D holographic images were produced. The equipment needed to view these holograms consists of only a simple point-light source. Conclusions--Holographic representation of myocardial and valve motion from echocardiographic data is feasible and allows the printing on a 2D medium of the complete heart cycle. Combined with the recent development of online holographic printing, this novel technique has the potential to improve reporting, visualization, and archiving of echocardiographic imaging. 相似文献
79.
The clinicopathological associations of 33 singleton infants who died with intraventricular haemorrhage (IVH) without hyaline membrane disease (HMD) ('IVH only') were compared with those of 39 infants who died with IVH+HMD over the same gestation range in order to determine what factors other than those related to HMD may contribute to the pathogenesis of IVH. The incidence of 'IVH only' was inversely related to gestational age in the Hammersmith birth population, whereas the incidence of IVH+HMD rose to a peak at 28-29 weeks' gestation. Infants with 'IVH only' lived longer on average than those with IVH+HMD despite a lower birthweight and shorter gestation. Infants who died in the first 12 hours from 'IVH only' had suffered severe birth asphyxia but in those who died later the main symptom was recurrent apnoea. Fewer infants with asphyxia but in those who died later the main symptom was.recurrent apnoea. Fewer infants with 'IVH only' were given alkali therapy or were connected to the ventilator as compared to those with IVH+HMD, but there were no differences in alkali therapy in those who lived for 12 hours or more. In the 'IVH only' group there was a high incidence of haemorrhage from other sites and of bacterial infections. It is suggested that, in the absence of HMD, extreme immaturity is the main factor determining the occurrence of IVH. Birth asphyxia, apnoeic attacks, haemorrhage, and infections may play subsidiary roles, possibly through development of metabolic acidosis. 相似文献
80.
Prevalence of risk factors for cardiovascular disease in Canadians 55 to 74 years of age: results from the Canadian Heart Health Surveys, 1986-1992 总被引:1,自引:1,他引:0 下载免费PDF全文
DB Langille MR Joffres KM MacPherson P Andreou SA Kirkland DR MacLean 《Canadian Medical Association journal》1999,161(8):S3-S9
BACKGROUND: By 2016, the proportion of Canadians older than 65 years of age will increase to 16%, and there will be an increase in the absolute number of cases of cardiovascular disease in older Canadians. The Canadian Heart Health Surveys database provides information about this population upon which health policy related to cardiovascular disease can be based. This paper presents for the first time population-based data on the risk factors for cardiovascular disease in older Canadians. METHODS: Canadians from all 10 provinces participated in surveys of cardiovascular risk factors; health insurance registries were used as sampling frames. In each province, probability samples of 2200 adults 18 to 74 years old not living in institutions, on reserves or in military camps were asked to participate in interviews and to undergo testing at clinics for major risk factors for cardiovascular disease. RESULTS: A total of 2739 men (response rate 70%) and 2617 women (response rate 66%) aged 55 to 74 years participated in the survey and also provided follow-up clinical measurements at the clinic. Overall, 52% of participants were hypertensive, 26% had isolated systolic hypertension, and 30% had a total blood cholesterol level of 6.2 mmol/L or greater. Rates of current smoking were lower in women than men (17% v. 22%). Overall, 87% of men and 78% of women who were current smokers smoked at least 10 cigarettes per day. Only slightly more than half of participants exercised at least once a week for at least 15 minutes, and almost half had a body mass index of 27 or greater. In only 4% was no major risk factor for cardiovascular disease detected. INTERPRETATION: Significant numbers of older Canadians have one or more major risk factors for cardiovascular disease. Many of these risk factors are amenable to modification. 相似文献