全文获取类型
收费全文 | 46857篇 |
免费 | 3515篇 |
国内免费 | 188篇 |
专业分类
耳鼻咽喉 | 376篇 |
儿科学 | 1525篇 |
妇产科学 | 1202篇 |
基础医学 | 6660篇 |
口腔科学 | 603篇 |
临床医学 | 5056篇 |
内科学 | 9827篇 |
皮肤病学 | 878篇 |
神经病学 | 5565篇 |
特种医学 | 1123篇 |
外科学 | 4172篇 |
综合类 | 383篇 |
一般理论 | 58篇 |
预防医学 | 5673篇 |
眼科学 | 617篇 |
药学 | 2993篇 |
中国医学 | 86篇 |
肿瘤学 | 3763篇 |
出版年
2024年 | 59篇 |
2023年 | 653篇 |
2022年 | 1091篇 |
2021年 | 2146篇 |
2020年 | 1301篇 |
2019年 | 1774篇 |
2018年 | 2040篇 |
2017年 | 1361篇 |
2016年 | 1520篇 |
2015年 | 1665篇 |
2014年 | 2029篇 |
2013年 | 2628篇 |
2012年 | 4206篇 |
2011年 | 4158篇 |
2010年 | 2112篇 |
2009年 | 1852篇 |
2008年 | 2949篇 |
2007年 | 2921篇 |
2006年 | 2785篇 |
2005年 | 2579篇 |
2004年 | 2282篇 |
2003年 | 2042篇 |
2002年 | 1747篇 |
2001年 | 203篇 |
2000年 | 158篇 |
1999年 | 216篇 |
1998年 | 349篇 |
1997年 | 262篇 |
1996年 | 216篇 |
1995年 | 176篇 |
1994年 | 127篇 |
1993年 | 119篇 |
1992年 | 71篇 |
1991年 | 70篇 |
1990年 | 57篇 |
1989年 | 60篇 |
1988年 | 53篇 |
1987年 | 42篇 |
1986年 | 44篇 |
1985年 | 38篇 |
1984年 | 50篇 |
1983年 | 46篇 |
1982年 | 33篇 |
1981年 | 43篇 |
1980年 | 29篇 |
1979年 | 19篇 |
1978年 | 15篇 |
1977年 | 22篇 |
1932年 | 15篇 |
1931年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
Normal cerebral perfusion measurements using arterial spin labeling: reproducibility, stability, and age and gender effects. 总被引:4,自引:0,他引:4
Laura M Parkes Waqar Rashid Declan T Chard Paul S Tofts 《Magnetic resonance in medicine》2004,51(4):736-743
Before meaningful conclusions can be drawn from clinical measures of cerebral blood perfusion, the precision of the measurement must be determined and set in the context of inter- and intrasubject sources of variability. This work establishes the reproducibility of perfusion measurements using the noninvasive MRI technique of continuous arterial spin labeling (CASL). Perfusion was measured in 34 healthy normal subjects. Intersubject variability was assessed, and age and gender contributions were estimated. Intersubject variation was found to be large, with up to 100% perfusion difference for subjects of the same age and gender. Repeated measurements in one subject showed that perfusion remains remarkably stable in the short term when compared with intersubject variation and the large capacity for perfusion change in the brain. A significant decrease in the ratio of gray-matter to white-matter perfusion was found with increasing age (0.79% per year (P < 0.0005)). This appears to be due mainly to a reduction in gray-matter perfusion, which was found to decrease by 0.45% per year (P = 0.04). Regional analysis suggested that the gray-matter age-related changes were predominantly localized in the frontal cortex. Whole-brain perfusion was 13% higher (P = 0.02) in females compared to males. 相似文献
65.
Sphingolipid metabolites in neural signalling and function 总被引:8,自引:0,他引:8
Sphingolipid metabolites, such as ceramide, sphingosine, sphingosine-1-phosphate (S1P) and complex sphingolipids (gangliosides), are recognized as molecules capable of regulating a variety of cellular processes. The role of sphingolipid metabolites has been studied mainly in non-neuronal tissues. These studies have underscored their importance as signals transducers, involved in control of proliferation, survival, differentiation and apoptosis. In this review, we will focus on studies performed over the last years in the nervous system, discussing the recent developments and the current perspectives in sphingolipid metabolism and functions. 相似文献
66.
67.
Meredith M Hancock Colette C Prosser Kanat Ransibrahmanakul Laura Lester Elana Craemer James A Bourgeois Lorenzo Rossaro 《Substance abuse treatment, prevention, and policy》2007,2(1):5
Methadone maintenance therapy for the treatment of opioid dependence continues to carry a social stigma. Until recently, patients
on methadone were not considered for liver transplantation. We describe the first case of a patient on methadone who received
a liver transplant for end stage liver disease and was successfully treated for recurrent hepatitis C. More than five years
post transplant and three years post viral clearance, the patient continues to do well and is stable on low-dose methadone.
This case emphasizes the need to reconsider the non-evidence based policy adopted by transplant centers that require methadone
maintenance therapy patients to stop methadone prior to consideration for transplant evaluation. 相似文献
68.
Public health law has been one of the leading contributors to the extension of life expectancy in the 20th century. Nonetheless, the legal infrastructure supporting public health law in the United States is underdeveloped and nonuniform. With national interest growing in public health agency accreditation, the individual legal approach taken by states may pose an obstacle to wholesale adoption of a proposed voluntary national model. This article describes the legal foundations supporting accreditation or assessment programs in states participating in the Multi-State Learning Collaborative, a project funded by the Robert Wood Johnson Foundation. The Turning Point Model State Public Health Act is recommended as one option to resolve the current impasse, assist in acceptance of a national accreditation model, and provide a common public health legal infrastructure. 相似文献
69.
J H Imatani S H Miller D C Buck R J Demuth P F Parshley 《Annals of plastic surgery》1986,16(2):116-120
Rats subjected to a standard electrical burn of 250 volts for 10 seconds receive a severe injury stimulating a pronounced systemic circulatory response. Initial postinjury hyperemia is replaced by a low perfusion state within 24 hours. Our study demonstrates the difficulty in isolating regional microcirculatory alterations under such circumstances. Modification of the burn model or the method of fluid resuscitation may minimize the influence of this dynamic systemic response. 相似文献
70.
Currently few subjective measures of Quality of Life (QoL) are available for use in developing countries, which limits their theoretical, methodological, and practical contribution (for example, exploring the relationship between economic development and QoL, and ensuring effective and equitable service provision). One reason for this is the difficulty of ensuring that translated measures preserve conceptual, item, semantic, operational, measurement; and functional equivalence (Herdman, M., Fox-Rushby, J., & Badia, X. (1998). Quality of Life Research, 7, 331), which is illustrated by an account of the translation, pre-piloting, and administration of a new individualised QoL measure, the Global Person Generated Index or 'GPGI'. The GPGI is based on the widely used Patient Generated Index (Ruta, Camfield, & Martin, (2004) Quality of Life Research, 13, 1545.) and offers many of the advantages of the participatory approaches commonly used in developing countries, with added methodological rigour, and quantitative outcomes. It was successfully validated in Bangladesh, Thailand, and Ethiopia, using quantitative and qualitative methods--open-ended, semi-structured interviews (SSIs), conducted immediately post-administration. Both the measure and method of 'qualitative validation' described later in the paper offer an exciting alternative for future researchers and practitioners in this field. The quantitative results suggest the GPGI shows cultural sensitivity, and is able to capture both the areas that are important to respondents, and aspects of life one would expect to impact on QoL in developing countries. There were strong correlation between scores from the GPGI and SSIs for the area of health, and moderate correlations for 'material wellbeing' (MWB)('Material wellbeing' refers to respondents' perceptions of their achievement in the areas of farming, debt reduction, assets, crops, livestock, job, land, property, and agriculture) and children. Weak to moderate correlations were observed between the Satisfaction with Life Scale and the GPGI; however, the highest coefficient was between the GPGI and the most conceptually similar item. Statistically significant differences were seen in GPGI scores between rich and poor, urban and rural respondents, and different countries. Health and material wellbeing scores, derived from the SSIs, also showed a linear relationship with GPGI scores, with a suggestion of curvilinearity at the higher levels, as predicted by a general QoL causal model. In conclusion, the GPGI has great potential for use in this area, especially when supported by extensive interviewer training, and supplemented with a cognitive appraisal schedule. 相似文献