全文获取类型
收费全文 | 1620篇 |
免费 | 128篇 |
国内免费 | 38篇 |
专业分类
耳鼻咽喉 | 37篇 |
儿科学 | 151篇 |
妇产科学 | 8篇 |
基础医学 | 175篇 |
口腔科学 | 42篇 |
临床医学 | 118篇 |
内科学 | 267篇 |
皮肤病学 | 12篇 |
神经病学 | 90篇 |
特种医学 | 119篇 |
外科学 | 308篇 |
综合类 | 45篇 |
预防医学 | 153篇 |
眼科学 | 14篇 |
药学 | 191篇 |
肿瘤学 | 56篇 |
出版年
2021年 | 16篇 |
2020年 | 11篇 |
2019年 | 27篇 |
2018年 | 21篇 |
2017年 | 16篇 |
2016年 | 20篇 |
2015年 | 24篇 |
2014年 | 43篇 |
2013年 | 52篇 |
2012年 | 72篇 |
2011年 | 71篇 |
2010年 | 33篇 |
2009年 | 36篇 |
2008年 | 44篇 |
2007年 | 81篇 |
2006年 | 58篇 |
2005年 | 73篇 |
2004年 | 64篇 |
2003年 | 70篇 |
2002年 | 56篇 |
2001年 | 52篇 |
2000年 | 55篇 |
1999年 | 52篇 |
1998年 | 47篇 |
1997年 | 26篇 |
1996年 | 18篇 |
1995年 | 21篇 |
1994年 | 14篇 |
1993年 | 21篇 |
1992年 | 44篇 |
1991年 | 39篇 |
1990年 | 48篇 |
1989年 | 57篇 |
1988年 | 44篇 |
1987年 | 53篇 |
1986年 | 40篇 |
1985年 | 28篇 |
1984年 | 9篇 |
1983年 | 17篇 |
1982年 | 10篇 |
1981年 | 13篇 |
1979年 | 15篇 |
1977年 | 13篇 |
1976年 | 9篇 |
1974年 | 11篇 |
1973年 | 12篇 |
1972年 | 15篇 |
1971年 | 23篇 |
1970年 | 10篇 |
1969年 | 17篇 |
排序方式: 共有1786条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
95.
OBJECTIVE: Study objectives were to assess the accuracy of a food record delivered on a personal digital assistant (PDA) and to examine sources of error from the PDA-based food record. METHODS: Thirty-nine adults recruited with a newspaper advertisement were trained to record food intake using DietMatePro, a dietary assessment program delivered on a PDA. After 3 d of use, subjects returned for a follow-up visit in which a 24-h recall was conducted. Subjects also were timed while recording an observed, weighed lunch. Recalled and actual food intakes were compared with estimates recorded by the subjects when using the PDA. Paired sample t tests and Pearson's correlations assessed means and measurements of association between DietMatePro data compared with the 24-h recall data and observed meal data. Bland-Altman plots were used to assess bias in food recording. Sources of error were quantified by using calories as the unit for comparison. RESULTS: There were no significant differences in daily totals for calories and macronutrients between DietMatePro data and comparison measurements. Pearson's correlations of associations between DietMatePro data and the comparison measurement ranged from 0.505 to 0.797 (P < 0.005, n = 28) for the 24-h recall and from 0.419 to 0.786 (P < 0.005, n = 33) for the observed lunch, depending on the nutrient measured. The largest source of absolute error in caloric estimation was attributable to portion size estimation error (49%). CONCLUSIONS: DietMatePro, a PDA-based dietary assessment program, provides a method of assessing energy and macronutrient intakes comparable to the 24-h recall in samples lacking dietary restrictions. 相似文献
96.
Cruz L Cardenas VM Abarca M Rodriguez T Reyna RF Serpas MV Fontaine RE Beasley DW Da Rosa AP Weaver SC Tesh RB Powers AM Suarez-Rangel G 《The American journal of tropical medicine and hygiene》2005,72(5):612-615
Epizootics of encephalitis in El Salvador killed 203 equines between November 2001 and April 2003. During an investigation of the outbreaks, 18 (25%) of 73 serum samples collected from stablemates of deceased animals in 2003 had antibodies to West Nile virus. Ten of these infections were confirmed by plaque reduction neutralization tests, suggesting West Nile virus has extended its range and spread to Central America. 相似文献
97.
98.
99.
OBJECTIVE: The aim of this study was to examine the efficacy of fluticasone administered once daily compared to twice daily in asthma. METHODOLOGY: A meta-analysis was performed of randomized double-blind trials of at least 4 weeks duration that compared fluticasone administered once versus twice a day and presented data on at least one clinical outcome measure. RESULTS: Six studies of 1517 children and adults with asthma met the inclusion criteria. Studies were predominantly in subjects with moderate asthma, treated with doses of fluticasone ranging from 200 to 500 microg per day. Twice-daily dosing was associated with significantly greater efficacy compared with once-daily dosing, for all outcome measures except night wakenings. The mean (95% CI) differences between twice and once-daily administration for FEV(1) and peak expiratory flow were 0.11 L (0.07-0.16) and 12.9 L/min (8.6-17.1), respectively. Twice-daily fluticasone was associated with significantly fewer withdrawals due to asthma than once-daily fluticasone, with an odds ratio of 0.44 (0.30-0.67). CONCLUSION: The findings suggest that twice-daily administration of fluticasone will provide greater therapeutic benefit than a once-daily morning regimen. 相似文献
100.
The 2004 World Health Organization classification of lung tumors 总被引:13,自引:0,他引:13