全文获取类型
收费全文 | 597篇 |
免费 | 23篇 |
国内免费 | 42篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 20篇 |
妇产科学 | 1篇 |
基础医学 | 57篇 |
口腔科学 | 13篇 |
临床医学 | 70篇 |
内科学 | 159篇 |
皮肤病学 | 4篇 |
神经病学 | 10篇 |
特种医学 | 198篇 |
外科学 | 58篇 |
综合类 | 8篇 |
预防医学 | 16篇 |
眼科学 | 1篇 |
药学 | 19篇 |
中国医学 | 1篇 |
肿瘤学 | 23篇 |
出版年
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2015年 | 17篇 |
2014年 | 11篇 |
2013年 | 13篇 |
2012年 | 8篇 |
2011年 | 10篇 |
2010年 | 18篇 |
2009年 | 20篇 |
2008年 | 8篇 |
2007年 | 34篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 10篇 |
1998年 | 36篇 |
1997年 | 33篇 |
1996年 | 37篇 |
1995年 | 30篇 |
1994年 | 46篇 |
1993年 | 25篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 34篇 |
1988年 | 35篇 |
1987年 | 34篇 |
1986年 | 22篇 |
1985年 | 19篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1975年 | 4篇 |
排序方式: 共有662条查询结果,搜索用时 15 毫秒
101.
石杉碱甲类似物的研究Ⅲ.N-甲基吡啶酮石杉碱甲类似物的合成 总被引:1,自引:0,他引:1
石杉碱甲(1)是从中草药石杉属植物千层塔(LycopodiumserratumThunb.)中分得的一种高效可逆的乙酰胆碱酯酶抑制剂,临床试验证实它对早老性痴呆症有显著疗效。本文报道N-甲基吡啶酮石杉碱甲类似物2和3的合成。2-甲氧基-5-甲氧羰基-11-亚甲基-5,9-甲撑环辛-7-烯并吡啶(9)在乙腈中用三甲基氯硅烷和碘化钠选择性脱保护以定量的产率得吡啶酮10,再用甲醇钠和碘甲烷甲基化得N-甲基吡啶酮11,11经碱性水解,Curtius重排和氨基的脱保护得N-甲基吡啶酮石杉碱甲类似物2。通过类似的途径从中间体2-甲氧基-5-甲氧羰基-7-甲基-11-酮-5,9-甲撑环辛-7-烯并吡啶(14)合成了类似物3。类似物2和3的乙酰胆碱酯酶抑制活性均低于天然石杉碱甲。 相似文献
102.
103.
Daniels DL; Czervionke LF; Millen SJ; Haberkamp TJ; Meyer GA; Hendrix LE; Mark LP; Williams AL; Haughton VM 《Radiology》1989,171(3):807-809
The authors evaluated magnetic resonance (MR) images obtained with intravenously administered gadolinium in ten patients who had facial paralysis and no facial nerve tumor. In patients with either Bell palsy (four patients) or facial paralysis after temporal bone surgery (six patients), intratemporal facial nerve enhancement was seen. Facial nerve enhancement on MR images proved to be a nonspecific finding. 相似文献
104.
105.
Thomas Kerr Brandon DL Marshall Cari Miller Kate Shannon Ruth Zhang Julio SG Montaner Evan Wood 《BMC public health》2009,9(1):171-7
Background
Street-involved youth contend with an array of health and social challenges, including elevated rates of blood-borne infections and mortality. In addition, there has been growing concern regarding high-risk drug use among street-involved youth, in particular injection drug use. We undertook this study to examine the prevalence of injection drug use and associated risks among street-involved youth in Vancouver, Canada. 相似文献106.
B-cell lymphoproliferative disorders in children after bone marrow transplantation: radiologic manifestations 总被引:1,自引:0,他引:1
The radiographic findings in five pediatric patients in whom unregulated B-cell lymphoproliferative disorders developed following bone marrow transplantation are described. Four patients received T-cell-depleted bone marrow from mismatched donors and one received nondepleted marrow from a matched sibling donor. These disorders are similar to B-cell lymphoproliferative disorders that have been described in other immunosuppressed hosts. They are associated with Epstein-Barr virus and range from polyclonal proliferation without cytogenetic abnormalities to monoclonal lymphoma with clonal cytogenetic changes. Unlike other postallograft lymphoproliferative processes, B-cell lymphoproliferative disorders in these patients have not responded to antiviral therapy, immunologic therapy, or chemotherapy. The radiographic patterns of disease include diffuse or focal hepatic involvement; gallbladder wall thickening; and pulmonary, soft-tissue, and basal-ganglion masses. These radiologic findings are not specific and evaluation of tissue histology is required for diagnosis. 相似文献
107.
Weinberg JB; Misukonis MA; Shami PJ; Mason SN; Sauls DL; Dittman WA; Wood ER; Smith GK; McDonald B; Bachus KE 《Blood》1995,86(3):1184-1195
108.
109.
DL Domingo MI Trujillo SE Council MA Merideth LB Gordon T Wu WJ Introne WA Gahl TC Hart 《Oral diseases》2009,15(3):187-195
Objective: Hutchinson-Gilford progeria syndrome (HGPS) is a rare early-onset accelerated senescence syndrome. In HGPS, a recently identified de novo dominant mutation of the lamin A gene ( LMNA ) produces abnormal lamin A, resulting in compromised nuclear membrane integrity. Clinical features include sclerotic skin, cardiovascular and bone abnormalities, and marked growth retardation. Craniofacial features include 'bird-like' facies, alopecia, craniofacial disproportion, and dental crowding. Our prospective study describes dental, oral soft tissue, and craniofacial bone features in HGPS.
Methods: Fifteen patients with confirmed p.G608G LMNA mutation (1–17 years, seven males, eight females) received comprehensive oral evaluations. Anomalies of oral soft tissue, gnathic bones, and dentition were identified.
Results: Radiographic findings included hypodontia ( n = 7), dysmorphic teeth ( n = 5), steep mandibular angles ( n = 11), and thin basal bone ( n = 11). Soft tissue findings included ogival palatal arch ( n = 8), median sagittal palatal fissure ( n = 7), and ankyloglossia ( n = 7). Calculated dental ages (9 months to 11 years 2 months) were significantly lower than chronological ages (1 year 6 months to 17 years 8 months) ( P = 0.002). Eleven children manifested a shorter mandibular body, anterior/posterior cranial base and ramus, but a larger gonial angle, compared to age/gender/race norms.
Conclusion: Novel oral-craniofacial phenotypes and quantification of previously reported features are presented. Our findings expand the HGPS phenotype and provide additional insight into the complex pathogenesis of HGPS. 相似文献
Methods: Fifteen patients with confirmed p.G608G LMNA mutation (1–17 years, seven males, eight females) received comprehensive oral evaluations. Anomalies of oral soft tissue, gnathic bones, and dentition were identified.
Results: Radiographic findings included hypodontia ( n = 7), dysmorphic teeth ( n = 5), steep mandibular angles ( n = 11), and thin basal bone ( n = 11). Soft tissue findings included ogival palatal arch ( n = 8), median sagittal palatal fissure ( n = 7), and ankyloglossia ( n = 7). Calculated dental ages (9 months to 11 years 2 months) were significantly lower than chronological ages (1 year 6 months to 17 years 8 months) ( P = 0.002). Eleven children manifested a shorter mandibular body, anterior/posterior cranial base and ramus, but a larger gonial angle, compared to age/gender/race norms.
Conclusion: Novel oral-craniofacial phenotypes and quantification of previously reported features are presented. Our findings expand the HGPS phenotype and provide additional insight into the complex pathogenesis of HGPS. 相似文献
110.
G D Kersley OBE TD DL MD DSC FRCP 《Medicine, conflict, and survival》2013,29(2):109-114
Any nuclear war would be horrific and our main aim should be universal abolition of nuclear weapons. Civil defence, with its medical attributes, could certainly increase the survival rate should a disaster occur. The effect of the explosion of a nuclear warhead is outlined, together with what could be done to reduce casualties. Nuclear winter is discussed and it is suggested that the results of computerization of doubtful surmises have been treated too much as proven facts. The possibility of its occurrence should not deter emergency planning. Civil defence can save lives, and the fact that medicine as we know it would cease to exist in an all‐out nuclear war does not excuse us from doing what we can to increase the survival rate, if the worst should happen. Action should therefore be taken now to plan decentralization of resources and to instruct the public in protection, first aid and self‐sufficiency. 相似文献