全文获取类型
收费全文 | 378篇 |
免费 | 17篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 15篇 |
妇产科学 | 8篇 |
基础医学 | 33篇 |
口腔科学 | 7篇 |
临床医学 | 18篇 |
内科学 | 37篇 |
皮肤病学 | 6篇 |
神经病学 | 143篇 |
特种医学 | 69篇 |
外科学 | 26篇 |
综合类 | 8篇 |
预防医学 | 3篇 |
眼科学 | 3篇 |
药学 | 9篇 |
中国医学 | 2篇 |
肿瘤学 | 7篇 |
出版年
2023年 | 2篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 16篇 |
2012年 | 20篇 |
2011年 | 20篇 |
2010年 | 17篇 |
2009年 | 17篇 |
2008年 | 19篇 |
2007年 | 25篇 |
2006年 | 19篇 |
2005年 | 8篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 18篇 |
1997年 | 14篇 |
1996年 | 17篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 10篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 10篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1939年 | 1篇 |
排序方式: 共有395条查询结果,搜索用时 31 毫秒
51.
52.
53.
54.
55.
56.
Intraoperative ultrasound examination of the brain 总被引:5,自引:0,他引:5
In a preliminary demonstration of cranial intraoperative real-time ultrasound, both supratentorial and posterior fossa scans displayed the pertinent anatomy. A grade III astrocytoma was visualized on the supratentorial scan as well. Ultrasound may be valuable for surgical planning and biopsy procedures because of its reliable depiction of intracranial anatomy and ease of use. 相似文献
57.
Benarroch EE 《Neurology》2011,77(16):1568-1576
58.
59.
Comparative mechanistic studies of de novo RNA synthesis by flavivirus RNA-dependent RNA polymerases
Selisko B Dutartre H Guillemot JC Debarnot C Benarroch D Khromykh A Desprès P Egloff MP Canard B 《Virology》2006,351(1):145-158
Flavivirus protein NS5 harbors the RNA-dependent RNA polymerase (RdRp) activity. In contrast to the RdRps of hepaci- and pestiviruses, which belong to the same family of Flaviviridae, NS5 carries two activities, a methyltransferase (MTase) and a RdRp. RdRp domains of Dengue virus (DV) and West Nile virus (WNV) NS5 were purified in high yield relative to full-length NS5 and showed full RdRp activity. Steady-state enzymatic parameters were determined on homopolymeric template poly(rC). The presence of the MTase domain does not affect the RdRp activity. Flavivirus RdRp domains might bear more than one GTP binding site displaying positive cooperativity. The kinetics of RNA synthesis by four Flaviviridae RdRps were compared. In comparison to Hepatitis C RdRp, DV and WNV as well as Bovine Viral Diarrhea virus RdRps show less rate limitation by early steps of short-product formation. This suggests that they display a higher conformational flexibility upon the transition from initiation to elongation. 相似文献
60.
Mimivirus, a parasite of Acanthamoeba polyphaga, is the largest DNA virus known; it encodes a cornucopia of proteins with imputed functions in DNA replication, modification, and repair. Here we produced, purified, and characterized mimivirus DNA ligase (MimiLIG), an NAD+-dependent nick joining enzyme homologous to bacterial LigA and entomopoxvirus DNA ligase. MimiLIG is a 636-aa polypeptide composed of an N-terminal NAD+ specificity module (domain Ia), linked to nucleotidyltransferase, OB-fold, helix-hairpin-helix, and BRCT domains, but it lacks the tetracysteine Zn-binding module found in all bacterial LigA enzymes. MimiLIG requires conserved domain Ia residues Tyr36, Asp46, Tyr49, and Asp50 for its initial reaction with NAD+ to form the ligase-AMP intermediate, but not for the third step of phosphodiester formation at a preadenylylated nick. MimiLIG differs from bacterial LigA enzymes in that its activity is strongly dependent on the C-terminal BRCT domain, deletion of which reduced its specific activity in nick joining by 75-fold without affecting the ligase adenylylation step. The DeltaBRCT mutant of MimiLIG was impaired in sealing at a preadenylylated nick. We propose that eukaryal DNA viruses acquired the NAD+-dependent ligases by horizontal transfer from a bacterium and that MimiLIG predates entomopoxvirus ligase, which lacks both the tetracysteine and BRCT domains. We speculate that the dissemination of NAD+-dependent ligase from bacterium to eukaryotic virus might have occurred within an amoebal host. 相似文献