全文获取类型
收费全文 | 1655篇 |
免费 | 150篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 65篇 |
妇产科学 | 50篇 |
基础医学 | 189篇 |
口腔科学 | 120篇 |
临床医学 | 220篇 |
内科学 | 329篇 |
皮肤病学 | 33篇 |
神经病学 | 112篇 |
特种医学 | 124篇 |
外科学 | 161篇 |
综合类 | 77篇 |
一般理论 | 1篇 |
预防医学 | 164篇 |
眼科学 | 15篇 |
药学 | 83篇 |
1篇 | |
中国医学 | 19篇 |
肿瘤学 | 40篇 |
出版年
2022年 | 11篇 |
2021年 | 18篇 |
2020年 | 17篇 |
2019年 | 28篇 |
2018年 | 33篇 |
2017年 | 11篇 |
2016年 | 20篇 |
2015年 | 45篇 |
2014年 | 39篇 |
2013年 | 62篇 |
2012年 | 86篇 |
2011年 | 96篇 |
2010年 | 78篇 |
2009年 | 62篇 |
2008年 | 69篇 |
2007年 | 93篇 |
2006年 | 63篇 |
2005年 | 52篇 |
2004年 | 62篇 |
2003年 | 64篇 |
2002年 | 43篇 |
2001年 | 51篇 |
2000年 | 28篇 |
1999年 | 32篇 |
1998年 | 46篇 |
1997年 | 30篇 |
1996年 | 40篇 |
1995年 | 40篇 |
1994年 | 33篇 |
1993年 | 22篇 |
1992年 | 31篇 |
1991年 | 18篇 |
1990年 | 18篇 |
1989年 | 30篇 |
1988年 | 31篇 |
1987年 | 32篇 |
1986年 | 23篇 |
1985年 | 26篇 |
1984年 | 19篇 |
1983年 | 13篇 |
1982年 | 15篇 |
1980年 | 13篇 |
1979年 | 10篇 |
1978年 | 11篇 |
1976年 | 13篇 |
1974年 | 10篇 |
1971年 | 9篇 |
1970年 | 9篇 |
1968年 | 10篇 |
1967年 | 11篇 |
排序方式: 共有1811条查询结果,搜索用时 0 毫秒
51.
52.
David L. Ergun Megan P. Rothney Mary K. Oates Yi Xia Wynn K. Wacker Neil C. Binkley 《Journal of clinical densitometry》2013,16(1):75-78
A dual-energy X-ray absorptiometry (DXA) application to measure visceral adipose tissue (VAT) in the android region of a total body DXA scan has recently been developed. This new application, CoreScan, has been validated on the Lunar iDXA (GE Healthcare, Madison, WI) densitometer against volumetric computed tomography. The geometric assumptions underlying the CoreScan model are the same on the Prodigy (GE Healthcare, Madison, WI) densitometer. However, differences between the peak X-ray voltage and detector array configurations may lead to differences in VAT quantification. The purpose of this study was to evaluate the agreement of Prodigy and iDXA CoreScan values and to characterize differences in VAT precision between the instruments. Data from volunteers with paired Prodigy and iDXA measurements were used to define empirical adjustments to the VAT algorithm parameters (n = 59) and validate performance on Prodigy (n = 62). Prodigy VAT measurements were highly correlated to iDXA (r = 0.984). The mean of the Prodigy-iDXA VAT volume differences was ?13.8 cm³ with a 95% confidence interval of ?45 to +17 cm³. The Bland-Altman 95% limits of agreement for the 2 methods were ?252 to +224 cm³. Measurement of short-term precision showed that measurement error variance on iDXA was smaller (p < 0.01) than Prodigy (coefficient of variance: 7.3% vs 9.8%). Precision results are in agreement with previous reports on the differences between Prodigy and iDXA for body composition measures. Prodigy and iDXA measures of VAT are similar, but the lower precision of the Prodigy may require investigators to target larger changes in VAT. 相似文献
53.
54.
55.
56.
57.
Thien Le Mercedes Xia Min Jia Nathan Sarkar Jerry Chen He Li Gary H. Wynn Robert J. Ursano Kwang H. Choi 《Psychopharmacology》2014,231(23):4569-4577
Rationale
Although chronic use of opiates can induce physical dependence and addiction, individual differences contributing to these symptoms are largely unknown.Objectives
Using intravenous morphine self-administration (MSA), we investigated whether individual differences in drug intake are associated with weight change, acoustic startle reflex (ASR), pre-pulse inhibition (PPI), and drug seeking during spontaneous withdrawal.Methods
Male Sprague-Dawley rats self-administered morphine (0.5 mg/kg/infusion) or saline for 3 weeks (4–6 h/day, 5 days/week) and drug intake and body weight were monitored daily. The ASR and the PPI (baseline, 1 day and 1 week) and drug seeking (1 week) were measured during spontaneous withdrawal.Results
Morphine animals did not gain weight (101 %?±?0.69), while the control animals did (115 %?±?1.06) after 3 weeks of self-administration. The ASR and the PPI were not significantly different between morphine and saline animals in 1-day or 1-week withdrawal. However, individual differences in initial (first 10 min), but not total (4–6 h), morphine intake of the daily sessions were positively correlated with weight change (r?=?0.437, p?=?0.037) and drug seeking (r?=?0.424, p?=?0.035) while inversely correlated with the ASR (r?=??0.544, p?=?0.005) in 1-week withdrawal from chronic morphine.Conclusions
A subgroup of animals that self-administered a larger amount of morphine at the beginning of the daily sessions exhibited subsequent weight gain, reduced ASR, and enhanced drug seeking in morphine withdrawal. Thus, individual differences in initial morphine intake may reveal a novel behavioral phenotype in opioid addiction. 相似文献58.
Robertson JD Gale RE Wynn RF Dougal M Linch DC Testa NG Chopra R 《British journal of haematology》2000,109(2):272-279
Human haemopoiesis undergoes profound changes throughout life, resulting in compromised regenerative capacity of haemopoietic stem cells. It has been suggested that telomere shortening results in senescence of haemopoietic stem cell subsets and may influence the balance between stem cell renewal and proliferation. Telomere length and telomerase activity was measured in whole blood leucocytes, neutrophils and T cells from cord blood and individuals aged from 1 year to 96 years. Rapid telomere shortening [700 base pairs (bp)] was demonstrated in the first year of life, followed by a gradual decline of 31 bp/year. T cells were shown to have longer telomeres than neutrophils (mean difference 372 bp, P = < 0.001) but demonstrated similar rates of shortening (20 +/- 0.3 bp/year vs. 22 +/- 0.3 bp/year). Telomerase was detectable in T cells but not in neutrophils, suggesting that telomerase is not the rate-limiting step for regulation of telomere length in haemopoietic cells. Stem cell utilization as measured by X chromosome inactivation patterns was found to be independent of telomere length. This supports the concept that age-dependent skewed haemopoiesis is the result of random stem cell loss or X-allelic exclusion rather than telomeric senescence. These studies provide insight into the ageing process and a reference point for evaluating replicative stress in individuals of different age groups. 相似文献
59.
目的 :了解我国卫生应急人员对突发公共卫生事件风险评估的认知状况,从文化程度、职称情况、单位性质、单位级别等方面进行比较,为提高卫生应急人员风险评估的认识和能力提供依据。方法 :采用问卷调查的方法,对全国(大陆地区)31个省(自治区、直辖市)承担突发公共卫生事件应急处置的卫生应急工作人员进行调查。采用描述性分析和χ2检验对调查数据进行分析。结果 :我国卫生应急人员对风险评估概念熟悉程度较低,且不同学历、不同职称、不同工作年限、不同机构、不同层级之间的认知存在一定差异;对风险评估工作内容的认知也存在分歧。结论 :应加强风险评估培训,健全风险评估制度,以全面提高卫生应急人员对风险评估的认知水平。 相似文献
60.
Woo So-Yeun Wong Chin Piow Win Nwet Nwet Lae Khine Zar Wynn Woo Bokyoung Elsabbagh Sherif Adel Liu Qian Qian Ngwe Hla Morita Hiroyuki 《Journal of natural medicines》2019,73(4):805-813
Journal of Natural Medicines - Jatropha multifida is a medicinal plant that belongs to the Euphorbiaceae family. Our investigation revealed that the chloroform extract of J. multifida stems showed... 相似文献