全文获取类型
收费全文 | 3504篇 |
免费 | 211篇 |
国内免费 | 79篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 200篇 |
妇产科学 | 54篇 |
基础医学 | 352篇 |
口腔科学 | 72篇 |
临床医学 | 407篇 |
内科学 | 758篇 |
皮肤病学 | 95篇 |
神经病学 | 157篇 |
特种医学 | 401篇 |
外科学 | 214篇 |
综合类 | 420篇 |
一般理论 | 1篇 |
预防医学 | 212篇 |
眼科学 | 47篇 |
药学 | 164篇 |
2篇 | |
中国医学 | 2篇 |
肿瘤学 | 226篇 |
出版年
2022年 | 17篇 |
2021年 | 30篇 |
2020年 | 27篇 |
2019年 | 28篇 |
2018年 | 47篇 |
2017年 | 35篇 |
2016年 | 32篇 |
2015年 | 55篇 |
2014年 | 73篇 |
2013年 | 97篇 |
2012年 | 91篇 |
2011年 | 104篇 |
2010年 | 114篇 |
2009年 | 114篇 |
2008年 | 167篇 |
2007年 | 211篇 |
2006年 | 170篇 |
2005年 | 158篇 |
2004年 | 134篇 |
2003年 | 71篇 |
2002年 | 67篇 |
2001年 | 73篇 |
2000年 | 74篇 |
1999年 | 71篇 |
1998年 | 141篇 |
1997年 | 169篇 |
1996年 | 142篇 |
1995年 | 113篇 |
1994年 | 132篇 |
1993年 | 108篇 |
1992年 | 53篇 |
1991年 | 65篇 |
1990年 | 63篇 |
1989年 | 79篇 |
1988年 | 62篇 |
1987年 | 66篇 |
1986年 | 74篇 |
1985年 | 57篇 |
1984年 | 34篇 |
1983年 | 24篇 |
1982年 | 35篇 |
1981年 | 40篇 |
1980年 | 34篇 |
1979年 | 24篇 |
1977年 | 25篇 |
1976年 | 37篇 |
1975年 | 20篇 |
1974年 | 14篇 |
1972年 | 14篇 |
1966年 | 12篇 |
排序方式: 共有3794条查询结果,搜索用时 15 毫秒
991.
992.
I. L. Smith S. Brown J. Nixon F. C. Cowdell S. Ersser C. Fernandez M. Goodfield C. M. Green P. Hampton J. T. Lear C. H. Smith L. Sunderland S. Tubeuf M. Wittmann 《Clinical and experimental dermatology》2017,42(2):185-188
Treatment of severe hand eczema (HE) that is resistant to topical potent corticosteroid treatment is challenging. In 2013, we surveyed 194 UK dermatologists to obtain information about their usual treatment pathways to inform the choice of the comparator in a trial of alitretinoin in severe HE (ALPHA trial); the results indicated that the treatment approaches favoured by UK dermatologists differ. Psoralen combined with ultraviolet A (PUVA) and alitretinoin were identified as the most frequent first‐line treatment options for hyperkeratotic HE, whereas oral corticosteroids were identified as the most frequent first‐line treatment for vesicular HE, followed by PUVA and alitretinoin. In terms of potential adverse effects of long‐term or repeated use, oral steroids and ciclosporin A were reported to cause most concern. There is uncertainty about which treatment gives the best short and long‐term outcomes, because of a lack of definitive randomised controlled trials evaluating the effectiveness of different treatment pathways in severe HE. 相似文献
993.
994.
甘草叶中黄酮类成分的化学研究 总被引:4,自引:0,他引:4
自甘草(Glycyrrhiza uralensis Fisch)的叶中分离到四个黄酮类化合物。根据理化性质,光谱(UV,MS,1HNMR)数据分析,分别确定结构为3,5,7,3′,4′-五羟基-5′-异戊烯基黄酮(Ⅰ),3,6,7,3′,4′-五羟基-2′-异戊烯基黄酮(Ⅱ),5,7,3′,4′-四羟基-5′-异戊烯基二氢黄酮(Ⅲ)和槲皮素-3,3′-二甲醚(Ⅳ)。其中,Ⅰ,Ⅱ和Ⅲ是新化合物,分别命名为乌拉尔醇(uralenol),新乌拉尔醇(neouralenol)和乌拉尔宁(uralenin)。Ⅳ在本属植物中为首次发现。Ⅲ为甘草叶中的主要黄酮类成分。本文解释了B环某些裂解碎片丰度与异戊烯基和氧取代基相对位置的关系。 相似文献
995.
996.
997.
998.
Verghis SB; Essigmann JM; Kadlubar FF; Morningstar ML; Lasko DD 《Carcinogenesis》1997,18(12):2403-2414
Mutagenesis by the human bladder carcinogen 4-aminobiphenyl (ABP) was
studied in single-stranded DNA from a bacteriophage M13 cloning vector. In
comparison to ABP lesions in double-stranded DNA, lesions in single-
stranded DNA were approximately 70-fold more mutagenic and 50-fold more
genotoxic. Sequencing analysis of ABP-induced mutations in the lacZ gene
revealed exclusively base-pair substitutions, with over 80% of the
mutations occurring at G sites; the G at position 6310 accounted for 25% of
the observed mutations. Among the sequence changes at G sites, G- ->T
transversions predominated, followed by G-->C transversions and G--
>A transitions. In order to further elucidate the mutagenic mechanism of
ABP, an oligonucleotide containing the major DNA adduct, N-
(deoxyguanosin-8-yl)-4-aminobiphenyl (dG(8-ABP)), was situated within the
PstI site of a single-stranded M13 genome. After in vivo replication of the
adduct containing ABP-modified and control (unadducted) genomes, the
mutational frequency and mutational specificity of the dG(8-ABP) lesion
were determined. The targeted mutational efficiency was approximately
0.01%, and the primary mutation observed was the G-->C transversion.
Thus dG(8-ABP), albeit weakly mutagenic at the PstI site, can contribute to
the mutational spectrum of ABP lesions.
相似文献
999.
1000.
Massive intracranial hemorrhage was diagnosed in utero in a 27-week-old fetus. The subsequent development of hydranencephaly was monitored by ultrasound until term. 相似文献