全文获取类型
收费全文 | 711篇 |
免费 | 64篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 44篇 |
妇产科学 | 7篇 |
基础医学 | 66篇 |
口腔科学 | 10篇 |
临床医学 | 85篇 |
内科学 | 138篇 |
皮肤病学 | 9篇 |
神经病学 | 34篇 |
特种医学 | 131篇 |
外科学 | 49篇 |
综合类 | 64篇 |
预防医学 | 56篇 |
眼科学 | 14篇 |
药学 | 44篇 |
肿瘤学 | 25篇 |
出版年
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 20篇 |
2014年 | 9篇 |
2013年 | 14篇 |
2012年 | 31篇 |
2011年 | 23篇 |
2010年 | 26篇 |
2009年 | 22篇 |
2008年 | 20篇 |
2007年 | 17篇 |
2006年 | 20篇 |
2005年 | 25篇 |
2004年 | 14篇 |
2003年 | 7篇 |
2002年 | 24篇 |
2001年 | 20篇 |
2000年 | 17篇 |
1999年 | 16篇 |
1998年 | 34篇 |
1997年 | 23篇 |
1996年 | 22篇 |
1995年 | 19篇 |
1994年 | 15篇 |
1993年 | 13篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 34篇 |
1989年 | 37篇 |
1988年 | 29篇 |
1987年 | 26篇 |
1986年 | 28篇 |
1985年 | 12篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1976年 | 3篇 |
1975年 | 8篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1971年 | 4篇 |
1969年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有779条查询结果,搜索用时 62 毫秒
41.
Donald E. Stull 《Quality of life research》2008,17(1):47-59
Objective Typical methods of analyzing data from clinical trials have shortcomings, notably comparisons of group means, use of change
scores from pre- and post-treatment assessments, ignoring intervening assessments, and focusing on direct effects of treatment.
A comparison of group means disregards the likelihood that individuals have different trajectories of change. Moreover, change
scores ignore intervening assessments that may provide useful information about change. This paper compares results from traditional
regression-based methods for analyzing data from a clinical trial (e.g., regression with change scores) with those of latent
growth curve modeling (LGM).
Methods LGM is a method that uses structural equation modeling techniques to model individual change, assess treatment effects and
the relationship among multiple outcomes simultaneously, and model measurement error. The consequence is more precise parameter
estimates while using data from all available time points.
Results Results demonstrate that LGM can yield stronger parameter estimates than the traditional regression-based approach and explain
more variance in the outcome. In trials where there is a true effect, but it is non-significant or marginally significant
using the traditional methods, LGM may provide evidence of this effect.
Conclusions Analysts are encouraged to consider LGM as an additional and informative tool for analyzing clinical trial or other longitudinal
data.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
42.
SK Bhattacharya MK Bhattacharya B Manna D Dutta A Deb P Dutta AG Goswami A Dutta S Sarkar A Mukhopadhaya T Krishnan TN Naik GB Nair 《Acta paediatrica (Oslo, Norway : 1992)》1995,84(2):160-164
In a case-control study to understand the risk factors for development of life-threatening dehydration, a total of 379 children comprising 243 cases (moderate or severe dehydration) and 136 controls (non or mild dehydration) up to 2 years of age suffering from acute watery diarrhoea were studied. By univariate analysis, the presence of vibrios in stool, withdrawal of breast feeding during diarrhoea, not giving fluids, including oral rehydration solution (ORS), during diarrhoea, frequent purging (> 8/ day), vomiting (> 2/day) and undernutrition were identified as risk factors. However, by multivariate analysis after controlling for confounders, withdrawal of breast feeding during diarrhoea (odds ratio (OR) = 6.8, p < 0.00001) and not giving ORS during diarrhoea (OR = 2.1, p < 0.006) were identified as significant risk factors. The confounding variables which also contributed significantly to increasing the risk were age (≤ 12 months; OR = 2.7, p = 0.001), frequent purging (> 8/day; OR = 4.1, p < 0.00001), vomiting (> 2/day; OR = 2.4, p = 0.001) and severe undernutrition (%median <60 weight-for-age of Indian Academy of Paediatrics classification; OR = 3.1, p = 0.001). We feel that these findings will be useful for Global and National Diarrhoeal Diseases Control Programmes for formulating intervention strategies for preventing death due to diarrhoeal dehydration. 相似文献
43.
At the Department of Radiation Oncology, Westmead Hospital, between 1980 and 2000, 60 patients with squamous cell carcinoma of anal canal or margin (including 15 with Stage IIIA or IIIB) were treated radically; 55 received chemoradiation (89% were prescribed mitomycin C and 5‐fluorouracil). Five‐year overall survival was 64% (95% confidence interval (CI): 48–79%), with a median survival of 9.75 years (median follow up 5.6 years, range 5 months to 22.5 years). Ten patients have died of disease. At 2 years the local control rate was 86%, and colostomy‐free survival was 83%. Relapse after 2 years was uncommon. Tumour size was the main factor driving outcomes, especially survival. Patients with larger tumours (T > 4 cm) had a hazard ratio for survival of 5.7 (95% CI: 1.8–17). Fourteen (24%) patients experienced treatment interruptions as a result of acute toxicity, including one death from neutropoenic sepsis. Seven (12%) patients, in total, experienced one or more late toxicities, grade 3 or above, including four women (all postmenopausal) who developed a radiation‐induced bone injury. Most patients with anal cancer can expect to retain a functional sphincter after chemoradiation/radiation. Further studies are in progress to determine the optimal chemoradiation protocol. 相似文献
44.
45.
Embryonic mouse striatal neurons and human neurons derived from the NT2/hNT stem cell line can be induced, in culture, to express the dopaminergic (DA) biosynthetic enzyme tyrosine hydroxylase (TH). The novel expression of TH in these cells is signaled by the synergistic interaction of factors present in the media, such as fibroblast growth factor 1 (FGF1) and one of several possible coactivators [DA, phorbol 12-myristate 13-acetate (TPA), isobutylmethylxanthine (IBMX), or forskolin]. Similarly, in vivo, it has recently been reported that the expression of TH in the developing midbrain is mediated by the synergy of FGF8 and the patterning molecule sonic hedgehog (Shh). In the present study, we examined whether the putative in vivo DA differentiation factors can similarly signal TH in our in vitro cell systems. We found that FGF8 and Shh induced TH expression in fewer than 2% of NT2/hNT cells and less than 5% of striatal neurons. The latter could be amplified to as much as 30% by increasing the concentration of growth factor 10-fold or by the addition of other competent coactivators (IBMX/forskolin, TPA, and DA). Additivity/inhibitor experiments indicated that FGF8 worked through traditional tyrosine kinase-initiated MAP/MEK signaling pathways. However, the Shh signal transduction cascade remained unclear. These data suggest that cues effective in vivo may be less successful in promoting the differentiation of a DA phenotype in mouse and human neurons in culture. Thus, our ability to generate DA neurons from different cell lines, for use in the treatment of Parkinson's disease, will depend on the identification of appropriate differentiation signals for each cell type under investigation. 相似文献
46.
Alveolar capillary dysplasia. Report of a case of prolonged life without extracorporeal membrane oxygenation (ECMO) and review of the literature 总被引:3,自引:0,他引:3
Al-Hathlol K Phillips S MK Seshia Casiro O Alvaro RE Rigatto H 《Early human development》2000,57(2):85-94
We describe an unusual infant with the diagnosis of alveolar capillary dysplasia who had a relatively prolonged life without extracorporeal membrane oxygenation (ECMO). We have used this case as a springboard for a thorough review of the literature. This was a full-term female infant who presented with a picture of persistent pulmonary hypertension of the newborn. She was treated as such, with various ventilatory modes, alkalinizing agents, surfactant therapy, tolazoline, prostacyclin and nitric oxide. Because of the prolonged clinical course the possibility of alveolar capillary dysplasia was raised. The parents refused ECMO. Despite all efforts she progressively deteriorated and died at 22 days of age. Macro- and microscopic examination of the lung at autopsy were diagnostic of alveolar capillary dysplasia. A detailed review of 39 cases published in the literature with comments regarding incidence, etiology, pathophysiology, clinical picture, diagnosis and treatment is presented. 相似文献
47.
48.
R Bahl N Bhandari MK Bhan M Saxena A Bagati 《Acta paediatrica (Oslo, Norway : 1992)》1996,85(11):1290-1294
Objectives : To determine the efficacy of antimicrobial treatment in non-dysenteric persistent diarrhoea in a community setting. Methods : In this double-blind field trial, 156 children aged 4 36 months with persistent diarrhoea not associated with Giardia lamblia infestation seeking treatment in a community outpatient clinic, were randomized to receive a combination of nalidixic acid and metronidazole, metronidazole alone, or placebo for 7 days. Results : In comparison with placebo, metronidazole treatment did not result in a significant reduction in the mean post-enrolment diarrhoeal duration and stool frequency, increase in the proportion of patients recovered by days 3, 5 and 7 of treatment, and increase in weight gain at days 7 and 14. Comparing the combination of nalidixic acid and metronidazole with metronidazole alone, 17.5% more children treated with the combination recovered by day 3 of treatment ( p = 0.08) and the mean stool frequency ascertained on day 7 for the previous 24 h was 26.8% less in them ( p = 0.05). The weight gains at days 7 and 14 were similar in the two groups. Conclusions : These findings indicate that metronidazole offers no therapeutic benefit in persistent diarrhoea not associated with Giardia lamblia and nalidixic acid has only a modest clinical benefit, which is not substantial enough to warrant its routine use. 相似文献
49.
50.