全文获取类型
收费全文 | 2063篇 |
免费 | 136篇 |
国内免费 | 45篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 110篇 |
妇产科学 | 26篇 |
基础医学 | 144篇 |
口腔科学 | 44篇 |
临床医学 | 291篇 |
内科学 | 329篇 |
皮肤病学 | 44篇 |
神经病学 | 58篇 |
特种医学 | 291篇 |
外科学 | 293篇 |
综合类 | 205篇 |
预防医学 | 135篇 |
眼科学 | 16篇 |
药学 | 120篇 |
2篇 | |
中国医学 | 32篇 |
肿瘤学 | 88篇 |
出版年
2022年 | 30篇 |
2021年 | 34篇 |
2020年 | 28篇 |
2018年 | 20篇 |
2017年 | 23篇 |
2016年 | 19篇 |
2015年 | 35篇 |
2014年 | 51篇 |
2013年 | 74篇 |
2012年 | 78篇 |
2011年 | 86篇 |
2010年 | 90篇 |
2009年 | 104篇 |
2008年 | 67篇 |
2007年 | 78篇 |
2006年 | 81篇 |
2005年 | 56篇 |
2004年 | 50篇 |
2003年 | 50篇 |
2002年 | 52篇 |
2001年 | 38篇 |
2000年 | 27篇 |
1999年 | 29篇 |
1998年 | 82篇 |
1997年 | 74篇 |
1996年 | 72篇 |
1995年 | 68篇 |
1994年 | 41篇 |
1993年 | 50篇 |
1992年 | 15篇 |
1991年 | 19篇 |
1990年 | 16篇 |
1989年 | 33篇 |
1988年 | 42篇 |
1987年 | 41篇 |
1986年 | 29篇 |
1985年 | 33篇 |
1984年 | 19篇 |
1983年 | 24篇 |
1982年 | 16篇 |
1980年 | 16篇 |
1977年 | 15篇 |
1963年 | 17篇 |
1960年 | 14篇 |
1959年 | 22篇 |
1958年 | 29篇 |
1957年 | 19篇 |
1956年 | 30篇 |
1955年 | 42篇 |
1954年 | 35篇 |
排序方式: 共有2244条查询结果,搜索用时 15 毫秒
101.
102.
Ageing appearance in China: biophysical profile of facial skin and its relationship to perceived age
AE Mayes PG Murray DA Gunn CC Tomlin SD Catt YB Wen LP Zhou HQ Wang M Catt SP Granger 《Journal of the European Academy of Dermatology and Venereology》2010,24(3):341-348
Background Perceived age is important to women and is a primary driver for topical product use and facial cosmetic surgery. Changes in facial features and biophysical skin parameters with chronological age and their associations with perceived age have not been described in Asian populations. Objective To investigate the relationship between biophysical properties of the skin, visual features of skin ageing and perceived facial age in Chinese women. Methods Facial photographs were collected of 250 Chinese women, aged 25–70 years in Shanghai, China. The perceived facial age was determined and related to the chronological age for each participant and to a range of visual assessments of skin appearance and objective biophysical measurements of the skin. The profile of changes in these parameters with age was investigated together with the differences in those parameters for women judged to look younger than their chronological age and those judged to look older than their chronological age. Results Large discrepancies in perceived age (up to 29 years) were found in women of the same chronological age. Each objective skin measure and visual assessment parameter had a stronger correlation with perceived age than with chronological age. The strongest relationships to perceived age were for wrinkles and hyperpigmentation. Skin colour, hydration and trans‐epidermal water loss (TEWL) had weaker associations with perceived age. Women judged to look older than their chronological age had significantly higher scores than those judged to look younger for coarse wrinkles and hyperpigmentation across all age groups. The appearance differences between these groups were evident in composite facial images of the same average chronological age. Conclusions We have identified the skin attributes which differ with perceived age in Chinese women. Perceived age is a better measure of the biological age of facial skin than is chronological age in this population. 相似文献
103.
104.
105.
CRISTIANE MARIA DA COSTA‐SILVA FABIANO JEREMIAS JULIANA FELTRIN
De SOUZA RITA
De CÁSSIA LOIOLA CORDEIRO LOURDES SANTOS‐PINTO ANGELA CRISTINA CILENSE ZUANON 《International journal of paediatric dentistry / the British Paedodontic Society [and] the International Association of Dentistry for Children》2010,20(6):426-434
International Journal of Paediatric Dentistry 2010; 20: 426–434 Background. The prevalence of molar incisor hypomineralization (MIH) varies considerably around the world; however, few studies have examined MIH in South American countries. Objective. To evaluate the prevalence, severity, and clinical consequences of MIH in Brazilian children residing in rural and urban areas of the municipality of Botelhos, Minas Gerais, Brazil. Methods. Children aged 6 to 12 years (n = 918) with all four‐first permanent molars erupted had these teeth evaluated according to the European Academy of Paediatric Dentistry (EAPD) criteria. The examinations were conducted by two previously trained examiners, and the dental impact caused by MIH was evaluated with the Decayed, Missing and Filled Teeth (DMFT) index (WHO). Results. Molar incisor hypomineralization was present in 19.8% of the 918 children, with a higher prevalence in rural areas. The majority of the defects presented were demarcated opacities without post‐eruptive structural loss, which has been considered as mild defects. Children with MIH had higher DMFT values. Conclusion. Despite the high prevalence of MIH, the severity of the defects was mild. The results indicate a positive association between MIH and the presence of dental caries. 相似文献
106.
目的:观察槲皮素(quercetin)体外对肝癌SMMC-7721细胞的生长抑制和诱导凋亡作用,并探讨线粒体在诱导凋亡机制中的作用。方法:以10、30、60和100μmol/L槲皮素作用于体外培养的SMMC-7721细胞,MTT法检测细胞生长抑制率;Annexi-V/PI双染流式细胞仪检测细胞凋亡情况;吖啶橙(acridine or-ange,AO)染色法观察细胞凋亡时形态变化;JC-1染色法检测细胞线粒体膜电位(mitochondrial membrane potential)变化。结果:槲皮素体外能抑制肝癌SMMC-7721细胞的生长(P<0.01),诱导细胞发生凋亡,并呈现量效和时效关系。10、30、60和100μmol/L槲皮素作用72h引起的细胞抑制率(F=343.71,P<0.01)和凋亡率(F=234.17,P<0.01)明显高于对照组。槲皮素作用48h后,AO染色图片可见细胞膜呈泡状膨出和凋亡小体等。凋亡过程中线粒体膜电位下降。结论:槲皮素体外能抑制肝癌SMMC-7721细胞生长,诱导细胞凋亡发生,线粒体膜电位下降在细胞凋亡过程中可能起到重要作用。 相似文献
107.
Peripheral nerve disorders may be classified into compressive or entrapment neuropathies and non‐compressive neuropathies. Muscle denervation recognized on MRI may be a useful sign in the diagnosis of peripheral nerve disorders. Acute or subacute denervation results in prolonged T2 relaxation time, producing increased signal in skeletal muscle on short tau inversion‐recovery and fat‐suppressed T2‐weighted images. Chronic denervation produces fatty atrophy of skeletal muscles, resulting in increased muscle signal on T1‐weighted images. This review will outline and illustrate the various ways that muscle denervation as seen on MRI may assist in the diagnosis and localization of peripheral nerve disorders. 相似文献
108.
以肺癌病理案例和语义网络技术为基础,结合了统一医学语言系统(UMLS),研究探讨了语义网络技术在电子病历中的实际应用,并最终实现了加入时序性特征的病理案例语义网络的表示。 相似文献
109.
110.
[目的]了解中国拉萨SOS儿童村儿童的膳食结构及营养状况,并根据膳食调查结果和存在的问题,提出合理膳食建议。[方法]2005年12月采用食物称重法,对中国拉萨SOS儿童村负责供养168名4~16岁儿童的17户家庭进行了为期5 d的膳食调查。[结果]17户家庭中绝大部分家庭膳食模式不尽合理,油脂摄入过多,大部分家庭脂肪供热百分比﹥30%;动物性食品摄入量及品种偏少,致使所有家庭的钙摄入量普遍不足,70%左右家庭的核黄素、40%左右家庭的蛋白质摄入量不足;多数家庭维生素A和铁虽然超出供给量标准,但是来源于动物性食品的比例很低。[结论]膳食模式的不合理性,势必影响儿童的正常发育和身心健康。因此,进一步加强营养知识的传授显得极为迫切和必要。 相似文献