全文获取类型
收费全文 | 5305篇 |
免费 | 290篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 27篇 |
儿科学 | 212篇 |
妇产科学 | 143篇 |
基础医学 | 567篇 |
口腔科学 | 51篇 |
临床医学 | 872篇 |
内科学 | 799篇 |
皮肤病学 | 100篇 |
神经病学 | 557篇 |
特种医学 | 77篇 |
外科学 | 510篇 |
综合类 | 40篇 |
一般理论 | 7篇 |
预防医学 | 677篇 |
眼科学 | 231篇 |
药学 | 355篇 |
中国医学 | 6篇 |
肿瘤学 | 374篇 |
出版年
2024年 | 7篇 |
2023年 | 30篇 |
2022年 | 37篇 |
2021年 | 81篇 |
2020年 | 61篇 |
2019年 | 105篇 |
2018年 | 125篇 |
2017年 | 103篇 |
2016年 | 105篇 |
2015年 | 124篇 |
2014年 | 171篇 |
2013年 | 282篇 |
2012年 | 417篇 |
2011年 | 399篇 |
2010年 | 241篇 |
2009年 | 199篇 |
2008年 | 356篇 |
2007年 | 389篇 |
2006年 | 370篇 |
2005年 | 351篇 |
2004年 | 362篇 |
2003年 | 340篇 |
2002年 | 287篇 |
2001年 | 64篇 |
2000年 | 47篇 |
1999年 | 46篇 |
1998年 | 48篇 |
1997年 | 44篇 |
1996年 | 45篇 |
1995年 | 39篇 |
1994年 | 34篇 |
1993年 | 44篇 |
1992年 | 32篇 |
1991年 | 21篇 |
1990年 | 20篇 |
1989年 | 23篇 |
1988年 | 22篇 |
1987年 | 16篇 |
1986年 | 15篇 |
1985年 | 12篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 16篇 |
1980年 | 10篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 6篇 |
排序方式: 共有5605条查询结果,搜索用时 8 毫秒
1.
2.
3.
4.
Deborah Bray Preston Anthony R D'Augelli Cathy D Kassab Richard E Cain Frederick W Schulze Michael T Starks 《AIDS education and prevention》2004,16(4):291-303
Research investigating predictors of risky sexual behavior of rural MSM is sparse, even though the prevalence of HIV in rural areas has increased. This study explored two sets of predictors of 93 rural MSM's levels of risky sexual behavior: mental health variables and stigma emanating from men's family members, health care professionals, and people in the rural communities in which they live. Over 47% of the men were found to be at modified high to high risk. Logistic regression using a continuation logit model was used to test the relationship of the predictor variables and the four levels of risk. Findings indicate that self-esteem was predictive of the highest sexual risk behavior but not lower levels of risk. Stigma was predictive of modified high sexual risk when compared to low and no risk categories. No variables differentiated men at low risk from men at no risk. 相似文献
5.
Background: Melatonin is gaining popularity as a sedative agent with children. This study sought to characterise this practice more precisely as well as examine aspects of its safety and efficacy in order to develop treatment guidelines.
Method: Postal surveys of two groups of psychiatrists: generic child psychiatrists and psychiatrists who regularly treat learning disabled children.
Results: Both groups (all of the specialists and 81% of the non-specialists) reported regular but not frequent use of melatonin in their usual practice, mostly for night-settling sleep problems refractory to behavioural modification strategies, commonly in the context of neurodevelopmental disability (especially autism). Treatment was described as being 'usually successful' and side-effects were highly infrequent and mild in nature. Variations in most prescribing practices were identified (dosage, timing).
Conclusions: Melatonin appears to represent a useful and relatively safe drug when used in specific circumstances; however, the evidence-base underpinning its use, particularly over the long-term, remains modest. Thus caution and clinical audit of practice is required. 相似文献
Method: Postal surveys of two groups of psychiatrists: generic child psychiatrists and psychiatrists who regularly treat learning disabled children.
Results: Both groups (all of the specialists and 81% of the non-specialists) reported regular but not frequent use of melatonin in their usual practice, mostly for night-settling sleep problems refractory to behavioural modification strategies, commonly in the context of neurodevelopmental disability (especially autism). Treatment was described as being 'usually successful' and side-effects were highly infrequent and mild in nature. Variations in most prescribing practices were identified (dosage, timing).
Conclusions: Melatonin appears to represent a useful and relatively safe drug when used in specific circumstances; however, the evidence-base underpinning its use, particularly over the long-term, remains modest. Thus caution and clinical audit of practice is required. 相似文献
6.
W. N. Charman 《Ophthalmic & physiological optics》2006,26(1):5-12
In the Cardiff acuity test, simple pictures on an otherwise neutral grey card are defined by borders consisting of a relatively broad white band flanked by black bands each half the width of the white band. Higher levels of acuity correspond to the ability to detect figures defined by narrower borders, the figure size remaining constant. It is sometimes implied that the acuity limit corresponding to each card can be equated with different levels of grating resolution, the total width of the border corresponding to the overall grating period. It is shown that although the spatial frequency spectra of the Cardiff figures, like those of other vanishing optotypes, lack very low-frequency components, they have a complex two-dimensional form. The figures have wide spatial bandwidth and no well-defined discrete frequency components. As a result, the relationship between measured Cardiff and grating acuity will vary somewhat, depending upon the particular optical, neural or other deficits of the individual being tested. 相似文献
7.
8.
Greg A Kossena William N Charman Ben J Boyd Christopher J H Porter 《Journal of controlled release》2004,99(2):217-229
The existence of a novel cubic liquid crystalline phase is described within the pseudo-ternary system comprising lauric acid, monolaurin, and simulated endogenous intestinal fluid (SEIF). This phase behaviour has been characterized using cross-polarizing light microscopy (CPLM), and the structure of the cubic phase identified by small angle X-ray scattering (SAXS). The presence of the cubic phase was found to be temperature sensitive within the 20-37 degrees C range making it putative material for in situ gelation purposes. The cubic phase was shown to have a high capacity to solubilise a model poorly water-soluble drug, cinnarizine, and initial in vitro release data highlight the potential of this phase to provide sustained release. Absorption of cinnarizine from the cubic phase was studied in an unconscious rat model via duodenal administration and blood sampling via the carotid artery. The rate of absorption was significantly reduced when compared to a simple suspension formulation, a likely combination of retarded erosion of the cubic phase together with hindered drug release from the cubic matrix. The results of this study suggest that this cubic phase may potentially be of benefit in the delivery of poorly water-soluble compounds due to its high loading capacity and potential for sustained release. The ability to manipulate this system using temperature may warrant further interest in delivery applications via other routes of administration. 相似文献
9.
Kevin O'Brien Jean Wright Frances Conboy YeWeng Sanjie Nicky Mandall Stephen Chadwick Ivan Connolly Paul Cook David Birnie Mark Hammond Nigel Harradine David Lewis Cathy McDade Laura Mitchell Alison Murray Julian O'Neill Mike Read Stephen Robinson Dai Roberts-Harry Jonathan Sandler Ian Shaw 《American journal of orthodontics and dentofacial orthopedics》2003,124(3):234-43; quiz 339
This study evaluated the effectiveness of early orthodontic treatment with the Twin-block appliance for the developing Class II Division 1 malocclusion. This multicenter trial was carried out in the United Kingdom. A total of 174 children, aged 8 to 10 years old, with Class II Division 1 malocclusion were randomly allocated to receive treatment with a Twin-block appliance or to an untreated, control group. Data were collected at the start of the study and 15 months later. Results showed that early treatment with Twin-block appliances resulted in reduction of overjet, correction of molar relationships, and reduction in severity of malocclusion. Most of this correction was due to dentoalveolar change, but some was due to favorable skeletal change. Early treatment with the Twin-block appliance is effective in reducing overjet and severity of malocclusion. The small change in the skeletal relationship might not be considered clinically significant. 相似文献
10.